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Bsnl electronics training report

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  • 1. INDEX 1. BROADBAND 1. Inroduction................................................ ....1 2. Definition................................................... ....2 2. GSM....................................................................3 3. Antenna 1. what is antenna............................................4 2. Types............................................................6 3. CELLULAR CONCEPTS............................................9 4. GSM ARHITECTURE.............................................10 1. Radio link ...................................................12 2. MOBILITY MANAGEMENT..................................14 3. CALL MANAGEMENT........................................18 4. HISTORY OF WIRELESS COMMUNICATION .......19 5. CDMA.................................................................24 i)WCDMA............................................................25 ii)3G MOBILE.......................................................27 1
  • 2. iii)IMS..................................................................28 iv)WIRELESS LAN AND BLUETOOTH.....................29 V)BEYOND 3G INTRODUCTION............................37 10. GPRS i).INTRODUCTION.................................................39 11. DSL...........................................................................41 12 . ADSL.......................................................................43 13. NGN........................................................................47 14 WIRELESS TECNOLOGY..........................................53 i)WIFI..................................................................54 ii)WIMAX.............................................................54 15 CABLE MODEM BASICS............................................55 1. PPPOE...........................................................57 16 INTRODUCTION TO MULTIPLAY...............................60 17 FTTH...........................................................................63 2
  • 3. 18 SMPS..........................................................................64 19 SDH.............................................................................69 20 PROJECT CDOT.......................................................................76 BROADBAND 3
  • 4. INTRODUCTION In 1960s people started thinking of potential value in allowing computers to share information on research and development in scientific and military fields. Internet was the result. Leaving what happened in between, the next milestone was in 1965 when Lawrence Roberts connected a computer at Massachusetts with a computer at California over dial-up telephone lines. The feasibility of wide area networking was proved. The Internet matured in the 70's as a result of the TCP/IP architecture replacing the earlier Network Control Protocol (NCP)and universally adopted by 1983. The National Science Foundation funded NSFNet as a cross- country 56 Kbps backbone for the Internet in 1986. As the commands for e-mail, FTP, and telnet were standardized, it became a lot easier for non-technical people to learn to use the nets. So people were able to make good use of the nets - to communicate with people around the world and to share files and resources. An archiver for ftp sites was created in 1989. The commands to search Archie were UNIX commands, and it required some knowledge of UNIX to use it to its full capability. Followed were 1. Wide Area Information Server (WAIS), which would index the full text of files in a database and allow searches of the files 2. Gopher, which needed no knowledge of UNIX or computer architecture to use. 3. VERONICA searchable index of Gopher menus Definition of Broadband The definition of broadband has changed over time to time. In the 1980s and early 1990s, broadband referred to rates greater than 45 megabits per second (Mbps), and "wideband" referred to rates between 1.5 and 45 Mbps. In 1995, broadband commonly referred to anything 1.5 Mbps and higher. In 2000, it was defined as a service that is at least 200 kbps in each direction.(Reference: BROADBAND BRINGING HOME THE BITS - NATIONAL ACADEMY PRESS, Washington, D.C.)In India, TRAI defines Broadband as: 4
  • 5. “An ‘always-on’ data connection that is able to support interactive services including Internet access and has the capability of the minimum download speed of 256 kilo bits per second (kbps) to an individual subscriber from the Point Of Presence (POP) of the service provider intending to provide Broadband service where multiple such individual Broadband connections are aggregated and the subscriber is able to access these interactive services including the Internet through this POP. The interactive services will exclude any services for which a separate licence is specifically required, for example, real-time voice transmission, except to the extent that it is presently permitted under ISP licence with Internet Telephony.” Applications A question to be necessarily considered is whether "broadband" refers exclusively to Internet service or is a more inclusive term that refers to a set of data communications services. Whether broadband is used to bring the Internet to the home or small business at much higher speed and with characteristics such as always-on, or is it really about delivering to the home a bundle of digital services. Definitely, it is going to offer many services such as Video on demand, live telecast or Interactive games in addition to a fast web browsing service. What is GSM The Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 212 countries and 5
  • 6. territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are digital call quality, and so is considered a second generation (2G) mobile phone system. This has also meant that data communication was built into the system from the 3rd Generation Partnership Project (3GPP). The main differentiator to previous mobile telephone systems, retrospectively dubbed 1G, is that the radio signals that 1G networks use are analog, while 2G networks are digital. Note that both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system. History of GSM GSM standard is an European standard which has addressed many problems directly related to compatibility, especially with the development of digital radio technology. From 1982 to 1985 discussions were held to decide between building an analog or digital system. After multiple field tests, a digital system was adopted for GSM.The next task was to decide between a narrow or broadband solution. In May 1987, the narrowband time division multiple access (TDMA) solution was chosen. Although standardized in Europe, GSM is not only a European standard. GSM networks are operational or planned in Europe, the Middle East, the Far East, Africa, North and South America, and Australia. The acronym GSM now aptly stands for Global System for Mobile communications WHAT IS ANTENNA 6
  • 7. Antennas transform wire-propagated waves into space-propagated waves. They receive electromagnetic waves and pass them onto a receiver or they transmit electromagnetic waves, which have been produced by a transmitter.All the features of passive antennas can be applied for reception and transmission alike (reciprocality). On one side RF cable is connected and the other side it is the environment, therefore the surroundings of the antenna have a strong influence on the antenna's electrical features. Principle of an antenna A) A transmitter sends a high frequency wave into a co-axial cable. A pulsing electrical field is created between the wires, which cannot free itself from the cable b) The end of the cable is bent open. The field lines become longer and are orthogonal to the wires. c) The cable is bent open at right angles. The field lines have now reached a length, which allows the wave to free itself from the cable. The apparatus radiates an electromagnetic wave, whereby the length of the two bent pieces of wire corresponds to half of the wavelength. This is the basic principle of λ/2-dipole antenna. Polarization Polarization can be defined as the direction of oscillation of the electrical field vector and has been discussed earlier. For Mobile communications generally vertical polarization is used. For Broadcast systems horizontal polarization is used. 7
  • 8. T Omni directional Antennas: The classical omni directional lamda/2 antennas are of two types 1. Ground Plane 2. λ/4-skirt Antenna The names indicate how the antenna is decoupled from the mast.In both cases the horizontal radiation pattern covers 360 ° and vertical half power beamwidth is 78 °.Hence there will be lot of waste of energy both upwards and downwards in the desired horizontal plane. Ground Plane Omni Directional Antenna In this case, a conductive plane is achieved via 3 counterweighted poles. The ground plane antenna can cover the complete frequency range because it is a wideband antenna. 8
  • 9. Directional Antennas Directional antennas are provided with reflectors behind the radiating element. This focuses the energy in a desired direction avoiding transmission in the rear side of the antenna. The directional antennas are classified into the following types: 1.Grid Parabolic Reflector antennas 2. Parabolic Reflector antennas. 3.Cassegrain antennas. 4. Array antennas. Directional Antennas The first two types of antennas are mainly used in fixed point-to-point radio links and the grid types are employed up to 2GHz whereas the solid parabolic reflector antennas are used for higher frequencies. The connectivity between the antennas to the equipments is by coaxial cable up to 2GHz and for higher frequencies it is by hollow copper tube called wave-guide. The beam width of these antennas depends on the diameter of the antenna and frequency of operation. They produce very narrow beams. Directional Antennas 9
  • 10. Cassegrain antennas are associated with Satellite communication are comparatively larger which makes them to be fixed on the ground or roof tops and orient themselves towards the satellite by operating gear arrangement either manually or using motors Directional Antennas Array antennas are more predominantly used in broadcasting and mobile communications. There are two types (i)End Fire Arrays,(ii)Panel Antennas End-fire Arrays:Yagi Antennas Yagi antennas are very common due to their simple and cheap method of construction. The gain and bandwidth of Yagi antennas are electrically coupled with one other which is an electrical disadvantage, ie. one criterion is weighed off the other. The mechanical concept is not suitable for extreme climatic conditions. 10
  • 11. Disadvantages of Copper Based Access Networks Eventhough there is a vast and extensive copper based access network,there are several disadvantages 1.Copper is costly and its resources are diminishing. 2.Installation of copper network is time consuming and costly affair Advantages of wireless 1. Provisioning of connectivity is faster. 2. Since there is no physical medium, fault liability is reduced. 3. Mobility is inherent. 4. Reconfiguration is simple. 5. Cost of installation is independent of distance. 6. Connections can be at longer distances than copper based network. 11
  • 12. Cellular Concepts - Introduction Even though multiple access techniques allowed multiple users to share the medium simultaneously, due to constraints in providing resources, an amount of blocking will exist. The amount of blocking is called “Grade Of Services”(GOS). GOS is a measure of the probability that a percentage of the offered traffic will be blocked or delayed. It is commonly expressed as the fraction of calls or demands that fail to receive immediate service. The aim is to achieve the GOS equal to 0 Based on GOS and resource availability (no. of carriers/no. of timeslots/both) the traffic handling capacity of the system is calculated. If this total traffic is divided by traffic per subscriber, we get number of subscribers supported by the system. For these purposes Erlang B table (Blocking calls cleared )is useful. Cellular Concepts - What is a cell? Cell is the basic geographic unit.They are base stations transmitting over that small area.Cells are usually represented on paper as hexagon.In reality the shape is not so because of the landscape and man-made structures.The base stations can be employing omni directional or directional antenna. Cell size depends on sub density and demand in that given area. To start with cell can be of maximum size 30Km radius and subsequently can be split into smaller cells. Usually in rural areas the cells are big and in urban will be smaller. 12
  • 13. GSM Architecture The figure represents a GSM reference model for a PLMN (Public Land Mobile Network). The GSM network is divided into four major systems 1. Switching system (SS) 2. Base station system (BSS) 3. Mobile station (MS) 4. Operation and maintenance centre(OMC) The switching system (SS) also called as Network and Switching System(NSS) is responsible for performing call processing and Subscriber-related functions. The switching system includes the following functional units 13
  • 14. 1. Mobile Switching Centre 2. Home Location Register 3. Visitor Location Register 4. Equipment Identity Register 5. Authentication Centre 6. GSM Architecture - The Functions Of MSC 1. Call handling that copes with the mobile nature of subscribers considering Location Registration,. Authentication of subscribers and equipment, Handover and Prepaid service. Home location register contains 1. The identity of mobile subscriber called IMSI (International Mobile Sub Identity) 2. ISDN directory number of mobile station. 3. Subscription information on services. 4. Service restrictions. 5. Location Information for call routing One HLR per GSM network is recommended and it may be a distributed database. Permanent data in HLR changed by man-machine interface. Temporary data like location information changes It refers to the terminal equipment used by the wireless subscriber. It consists of 1. SIM -Subscriber Identity Module 2. Mobile Equipment. SIM is removable and with appropriate SIM, the network can be accessed using various mobile equipments. The equipment identity is not linked to the subscriber. The equipment is validated separately with IMEI and EIR. The SIM contains an integrated circuit chip with a microprocessor, random access memory (RAM)and read only memory (ROM). SIM should be valid and authenticate the validity of MS while accessing the network. 14
  • 15. SIM also stores subscriber related information like IMSI ,cell location identity etc. GSM RADIO LINK Introduction BTS and MS are connected through radio link this air interface is called Um.A radio wave is subject to attenuation,reflection,Doppler shift and interference from other transmitter.These effects causes loss of signal strength and distortion which will impact the quality of voice or data. To cope with the harsh conditions,GSM make use of an efficient and protective signal processing. Proper cellular design must ensure that sufficient radio coverage is provided in the area. Special Features of GSM 1. Authentication. 2. Encryption 3. Time Slot Staggering 4. Timing Advance 5. Discontinuous transmission 6. Power Control 7. Adoptive equalization 8. Slow Freq Hopping 15
  • 16. Authentication Since the air interface is vulnerable to frauduland access,it is necessary to employ authentication before extending the services to this subscriber.Authentication is built around the following notions. 1. Authentication Key(Ki) resides only in two places, SIM card and Authentication Centre. 2. Authentication Key (Ki) is never transmitted over air. It is virtually impossible for unauthorised individuals to obtain this key to impersonate a given mobile subscriber. Authentication Parameters The MS is authenticated by the VLR with a process that uses three parameters: 1. RAND which is completely random number 2. SRES which is an authentication signed response.It is generated by applying an authentication algorithm (A3) to RAND and Ki 3. Kc which is cipher key.The Kc parameter generated by applying the cipher key generation algorithm (A8) to RAND and Ki. Encryption/Ciphering Data is encrypted at the transmitter side in blocks of 114 bits by taking 114-bit plain text data bursts and performing an EXOR(Exclusive OR)logical function operation with a 114-bit cipher block. The decryption function at the receiver side is performed by taking the encrypted data block of 114 bits and going through the same"exclusive OR"operation using the same 114-bit cipher block that was used at the transmitter. The cipher block used by both ends of transmission path for a given transmission direction is produced at the BSS and MS by an encryption algorithm called A5.The A5 algorithm uses a 64-bit cipher key(Kc),produced during the authentication process during call setup and the 22-bit TDMA frame number(COUNT) which takes decimal values from 0 through 2715647 and has a repetition time 3.48 hours (hyperframe interval).The A5 algorithm actually produce two cipher blocks during each TDMA period.One for the uplink path and the other for the downlink path. Frequency Hopping 16
  • 17. The mobile station already has to be frequency agile, meaning it can move between a transmit, receive, and monitor time slot within one TDMA frame, which normally are on different frequencies. GSM makes use of this inherent frequency agility to implement slow frequency hopping, where the mobile and BTS transmit each TDMA frame on a different carrier frequency. MOBILITY MANAGEMENT Network Attachment Network attachment is a process of selecting an appropriate cell(radio frequency)by the mobile station to provide the available services,and making its location known to the network The process starts when the mobile station is switched on,and ends when the mobile station enters the idle mode.In idle mode the mobile station does not have a traffic channel allocated to make or receive a call,but the Public Land Mobile Network(PLMN) is aware of the existence of the mobile station within the chosen cell. Cell Identification When a mobile station is switched on it attempts to make contact with a GSM PLMN by performing the following action 1. Measures the BCCH channels. 2. Search for a suitable cell. The mobile station measures the signal strength of the BCCH(Broadcast Control Channel)channels received.It stores in a list of information of about 30 of these BCCH channels,such as the signal strength and the frequency corresponding to these BCCH channels. Call to an active Mobile Station As an active Mobile Station(MS) moves around in the coverage area of a Public Land Mobile Network(PLMN),it reports its movements so that it 17
  • 18. can be located when required using the Locations Update procedure. When a Mobile Services Switching Center(MSC) in the network needs to establish a call to an MS operating in its area the following Happens: Location area To eliminate the need for network-wide paging broadcasts,the PLMN needs to know the approximate positions of the MSs that are active within its coverage area.To enable the approximate positions of any MS to be represented by a single parameter,the total area covered by the network is divided into location areas. A Location area(LA) is a cluster of one or more radio cells.The cell cluster fulfills the following requirements: 1. The BTSs in a location area are controlled by one or more BSCs 2. BSCs that serve the same location area are always connected to the same MSC 3. Radio cells with BTSs controlled by a common BSC can lie in different location areas. Location area Identity Every radio transmitter in the PLMN broadcast,via a control channel,a Location Area Identity(LAI) code to identify the location area that it serves. When an MS is not engaged in a call,it automatically scans the BCCH transmitted by the base stations in the locality and selects the channel that is delivering the strongest signal.The LAI code broadcast by the selected channel identifies the location area in which the MS is currently situated.This LAI code is stored in the Subscriber Identity Module(SIM) of the mobile equipment. . Types of Identification Numbers During the performance of the location update procedure and the processing of a mobile call different types of numbers are used: 1. Mobile station ISDN Number(MSISDN) 2. Mobile Subscriber Roaming Number(MSRN) 3. International Mobile Subscriber Identity(IMSI) 4. Temporary Mobile Subscriber Identity(TMSI) 18
  • 19. 5. Local Mobile Station Identity(LMSI) Each number is stored in the HLR and/or VLR. Mobile Station ISDN Number The MSISDN is the directory number allocated to the mobile subscriber.It is dialed to make a telephone call to the mobile subscriber. The number consists of Country Code(CC) of the country in which the mobile station is registered(for example India 91) followed by national mobile number which consists of Network Destination Code(NDC) and Subscriber Number(SN).A NDC is allocated to each GSM PLMN. The composition of the MSISDN is such that it can be used as a global title address in the Signaling Connection Control Part(SCCP) for routing message to the HLR of the mobile subscriber Mobile Station Roaming Number The MSRN is the number required by tye gateway MSC to route an incoming call to a MS that is not currently under the gateway's control Using the MSISDN a mobile terminated call is routed to the gateway MSC.Based on this MSISDN the gateway MSC requests for a MSRN to route the call to the current visited MSC International Mobile Subscriber Identity A MS is identified by its IMSI.The IMSI is embodied in the SIM of the mobile equipment.It is provided by the MS anytime it accesses the network Mobile Country Code(MCC) : The MCC component of the IMSI is a 3-digit code that uniquely identifies the country of the domicile of the subscriber.It is assigned by the ITU-T Mobile Network Code(MNC) : The MNC component is a 2-digit code that identifies the home GSM PLMN of the mobile subscriber.It is assigned by the government of each country.For GSM-1900 a 3-digit MNC is used. Mobile Subscriber Identification Number(MSIN) : The MSIN is a code that identifies the subscriber within a GSM PLMN.It is assigned by the operator. Hand Over 19
  • 20. The process of automatically switching a call in progress from one traffic channel to another to neutralise the adverse effects of the user movements. Hand over process will be started only if power control is not helpful anymore. The Hand Over process is MAHO(Mobile Assisted Hand Over).It starts with the Down Link Measurements by the MS(Strength of the signal from BTS,Quality of the signal from BTS).MS can measure the Signal Strength of the 6 best neighboring BTS down link(candidate list) CALL MANAGEMENT Mobile To Land Call Scenario (Mobile Origination) Phases of Mobile To Land Call . The following table lists the phases of a Mobile To Land Call 1. Request for services;the MS requests to setup a call 2. Authentication : the MSC/VLR requests the AUC for authentication parameters,Using these parameters the MS is authenticated. 3. Ciphering : using the parameters, which were made available earlier during the authentication, the uplink and the downlink are ciphered 4. Equipment Validation :the MSC/VLR requests the EIR to check the IMEI for validity 5. Call setup :the MSC establishes a connection to the MS. 6. Handover(s) 7. Call release;the speech path is released Mobile To Land Call Scenario-Phases of Mobile To Land Call The user enters the digits of the telephone with STD code incase of land line or without STD code incase of mobile and presses the "send" key after all digits have been entered 1. MS transmits a channel request message over the Random Access Channel(RACH) 2. Once the BSS receives the Channel Request message,it allocates a Stand-alone Dedicated Control Channel(SDCCH) and forwards this channel assignment information to the MS over the access Grant Channel(AGCH).It is over the SDCCH that the MS will communicate with the BSS and MSC until a traffic channel is assigned. 3. The MS transmits a service request message to the BSS over the SDCCH.Included in 20
  • 21. this message is the MS TMSI and Location Area Identification(LAI).The BSS forwards the service request message to the MSC/VLR. Mobile To Land Call Scenario-Phases of Mobile To Land Call The IMEI code is secure and physically protected against The Equipment Identity Register(EIR) is responsible for storing the IMEI codes that identify the mobile-equipment deployed in the GSM system. History Of Wireless Communication The idea of cell-based mobile radio systems appeared at Bell Laboratories (in USA) in the early 1970s. However, mobile cellular systems were not introduced for commercial use until the 1980s. During the early 1980s, analog cellular telephone systems experienced a very rapid growth in Europe, particularly in Scandinavia and the United Kingdom. Today cellular systems still represent one of the fastest growing telecommunications systems. But in the beginnings of cellular systems, each country developed its own system, which was an undesirable situation for the following reasons: 1. The equipment was limited to operate only within the boundaries of each country. 2. The market for each mobile equipment was limited. In order to overcome these problems, the Conference of European Posts and Telecommunications (CEPT) formed, in 1982, the Group Special Mobile (GSM) in order to develop a pan-European mobile cellular radio system (the GSM acronym became later the acronym for Global System for Mobile communications). The standardized system had to meet certain criteria: Cellular systems The cellular structure In a cellular system, the covering area of an operator is divided into cells. A cell corresponds to the covering area of one transmitter or a small collection of transmitters. The size of a cell is determined by the transmitter's power. 21
  • 22. The concept of cellular systems is the use of low power transmitters in order to enable the efficient reuse of the frequencies. In fact, if the transmitters used are very powerful, the frequencies can not be reused for hundred of kilometers as they are limited to the covering area of the transmitter. The frequency band allocated to a cellular mobile radio system is distributed over a group of cells and this distribution is repeated in all the covering area of an operator. The whole number of radio channels available can then be used in each group of cells that form the covering area of an operator. Frequencies used in a cell will be reused several cells away. The distance between the cells using the same frequency must be sufficient to avoid interference. The frequency reuse will increase considerably the capacity in number of users. Compatibility with other systems such as ISDN The decision of adopting a digital technology for GSM was made in the course of developing the standard. During the development of GSM, the telecommunications industry converted to digital methods. The ISDN network is an example of this evolution. In order to make GSM compatible with the services offered by ISDN, it was decide that the digital technology was the best option. Additionally, a digital system allows, easily than an analog one, the implementation of future improvements and the change of its own characteristics. Architecture of the GSM network The GSM technical specifications define the different entities that form the GSM network by defining their functions and interface requirements. The GSM network can be divided into four main parts: The architecture of the GSM network is presented in figure Mobile Station A Mobile Station consists of two main elements: 1.The Terminal There are different types of terminals distinguished principally by their power and application: 1. The `fixed' terminals are the ones installed in cars. Their maximum allowed output power is 20 W. 2. The GSM portable terminals can also be installed in vehicles. Their maximum allowed output power is 8W. 3. The handheld terminals have experienced the biggest success thanks to the weight and volume, which are continuously decreasing. These terminals can 22
  • 23. emit up to 2 W. The evolution of technologies allows decreasing the maximum allowed power to 0.8 W. 2.The SIM The SIM is a smart card that identifies the terminal. By inserting the SIM card into the terminal, the user can have access to all the subscribed services. Without the SIM card, the terminal is not operational. The SIM card is protected by a four-digit Personal Identification Number (PIN). In order to identify the subscriber to the system, the SIM card contains some parameters of the user such as its International Mobile Subscriber Identity (IMSI). Another advantage of the SIM card is the mobility of the users. In fact, the only element that personalizes a terminal is the SIM card. Therefore, the user can have access to its subscribed services in any terminal using its SIM card. The Base Station Subsystem The BSS connects the Mobile Station and the NSS. It is in charge of the transmission and reception. The BSS can be divided into two parts: The Base Transceiver Station The BTS corresponds to the transceivers and antennas used in each cell of the network. A BTS is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between one and sixteen transceivers depending on the density of users in the cell. The Base Station Controller The BSC controls a group of BTS and manages their radio resources. A BSC is principally in charge of handovers, frequency hopping, exchange functions and control of the radio frequency power levels of the BTSs. The Network and Switching Subsystem Its main role is to manage the communications between the mobile users and other users, such as mobile users, ISDN users, fixed telephony users, etc. It also includes data bases needed in order to store information about the subscribers and to manage their mobility. The different components of the NSS are described below. The Mobile services Switching Center (MSC) It is the central component of the NSS. The MSC performs the switching functions of the network. It also provides connection to other networks. 23
  • 24. The Gateway Mobile services Switching Center (GMSC) A gateway is a node interconnecting two networks. The GMSC is the interface between the mobile cellular network and the PSTN. It is in charge of routing calls from the fixed network towards a GSM user. The GMSC is often implemented in the same machines as the MSC. Home Location Register (HLR) The HLR is considered as a very important database that stores information of the subscribers belonging to the covering area of a MSC. It also stores the current location of these subscribers and the services to which they have access. The location of the subscriber corresponds to the SS7 address of the Visitor Location Register (VLR) associated to the terminal Visitor Location Register (VLR) The VLR contains information from a subscriber's HLR necessary in order to provide the subscribed services to visiting users. When a subscriber enters the covering area of a new MSC, the VLR associated to this MSC will request information about the new subscriber to its corresponding HLR. The VLR will then have enough information in order to assure the subscribed services without needing to ask the HLR each time a communication is established. The VLR is always implemented together with a MSC; so the area under control of the MSC is also the area under control of the VLR. The Authentication Center (AuC) The AuC register is used for security purposes. It provides the parameters needed for authentication and encryption functions. These parameters help to verify the user's identity. The Equipment Identity Register (EIR) The EIR is also used for security purposes. It is a register containing information about the mobile equipments. More particularly, it contains a list of all valid terminals. A terminal is identified by its International Mobile Equipment Identity (IMEI). The EIR allows then to forbid calls from stolen or unauthorized terminals (e.g., a terminal which does not respect the specifications concerning the output RF power). The GSM Inter-working Unit (GIWU) The GIWU corresponds to an interface to various networks for data communications. During these communications, the transmission of speech and data can be alternated. 24
  • 25. The GSM functions In this paragraph, the description of the GSM network is focused on the different functions to fulfill by the network and not on its physical components. In GSM, five main functions can be defined: Mobility Management The MM function is in charge of all the aspects related with the mobility of the user, specially the location management and the authentication and security. The GSM radio interface The radio interface is the interface between the mobile stations and the fixed infrastructure. It is one of the most important interfaces of the GSM system. One of the main objectives of GSM is roaming. Therefore, in order to obtain a complete compatibility between mobile stations and networks of different manufacturers and operators, the radio interface must be completely defined. The spectrum efficiency depends on the radio interface and the transmission, more particularly in aspects such as the capacity of the system and the techniques used in order to decrease the interference and to improve the frequency reuse scheme. The specification of the radio interface has then an important influence on the spectrum efficiency. 25
  • 26. CDMA Introduction Code Division Multiple Access(CDMA) is a access method in which large number of transmissions are combined on the same RF channel at the same time but are separated by unique assigned “codes”. This CDMA Access method is used to provide mobile telephony and works on the cellular principle. Overview of CDMA System Access network, the network between local exchange and subscriber, in the Telecom Network accounts for a major portion of resources both in terms of capital and manpower. So far, the subscriber loop has remained in the domain of the copper cable providing cost effective solution in past. Quick deployment of subscriber loop, coverage of inaccessible and remote locations coupled with modern technology has led to the emergence of new Access Technologies. The various technological options available are as follows: 1. Multi Access Radio Relay 2. Wireless In Local Loop 3. Fiber In the Local Loop Wireless In Local Loop (WILL) Fixed Wireless telephony in the subscriber access network also known as Wireless in Local Loop (WLL) is one of the hottest emerging market segments in global telecommunications today. WLL is generally used as “the last mile solution” to deliver basic phone service expeditiously where none has existed before. Flexibility and expediency are becoming the key driving factors behind the deployment of WILL. WLL shall facilitate cordless telephony for residential as well as commercial complexes where people are highly mobile. It is also used in remote areas where it is uneconomical to lay cables and for rapid development of telephone services. The technology employed shall depend upon various radios accesses techniques, like FDMA, TDMA and CDMA. 26
  • 27. Different technologies have been developed by the different countries like CT2 from France, PHS from Japan, DECT from Europe and DAMPS & CDMA from USA. Let us discuss CDMA technology in WILL application as it has a potential ability to tolerate a fair amount of interference as compared to other conventional radios. This leads to a considerable advantage from a system point of view. Advantages of CDMA System CDMA wireless access provides the following unique advantages: WCDMA Background There has been a tremendous growth in wireless communication technology over the past decade. The significant increase in subscribers and traffic, new bandwidth consuming applications such as gaming, music down loading and video streaming will place new demands on capacity. The answer to the capacity demand is the provision of new spectrum and the development of a new technology – Wideband CDMA or hereinafter referred to as WCDMA. WCDMA was developed in order to create a global standard for real time multimedia services that ensured international roaming. With the support of ITU (International Telecommunication Union) a specific spectrum was allocated – 2GHz for 3G telecom systems. The work was later taken over by the 3GPP (3rd Generation Partnership Project), which is now the WCDMA specification body with delegates from all over the world. Ericsson has for a long time played a very active role in both ITU and 3GPP and is a major contributor to WCDMA and the fulfillment of the vision of a global mobile telecommunication system. Code Division Multiple Access and WCDMA Code Division Multiple Access (CDMA) is a multiple access technology where the users are separated by unique codes, which means that all users can use the same frequency and transmit at the same time. With the fast development in signal processing, it has become 27
  • 28. feasible to use the technology for wireless communication, also referred to as WCDMA and CDMA2000. In cdmaOne and CDMA2000, a 1.25 MHz wide radio signal is multiplied by a spreading signal (which is a pseudo-noise code sequence) with a higher rate than the data rate of the message. The resultant signal appears as seemingly random, but if the intended recipient has the right code, this process is reversed and the original signal is extracted. Use of unique codes means that the same frequency is repeated in all cells, which is commonly referred to as a frequency re-use of 1. WCDMA is a step further in the CDMA technology. It uses a 5 MHz wide radio signal and a chip rate of 3.84 Mcps, which is about three times higher than the chip rate of CDMA2000 (1.22 Mcps). The main benefits of a wideband carrier with a higher chiprate are: 1. Support for higher bit rates 2. Higher spectrum efficiency thanks to improved trunking efficiency (i.e. a better statistical averaging) 3. Higher QoS Further, experience from second-generation systems like GSM and cdmaOne has enabled improvements to be incorporated in WCDMA. Focus has also been put on ensuring that as much as possible of WCDMA operators’ investments in GSM equipment can be reused. Examples are the re-use and evolution of the core network, the focus on co-sitting and the support of GSM handover. In order to use GSM handover the subscribers need dual mode handsets. 28
  • 29. 3 G MOBILE (UMTS) 1. UMTS is the convergence of mobile communications, Information Technology (IT) and multimedia technologies. UMTS creates new opportunities for network operators, service providers and content providers to generate revenue and seize market share. The benefit of UMTS is richer, more powerful communication.UMTS is a suite of radio and network technologies that provide: 2. better spectrum efficiency, 3. high data transmission rates (up to 2 Mbit/s), worldwide roaming capability, 4. the capability to offer new multimedia applications and services, 5. interoperability with both fixed and mobile telecommunications services. UMTS is the natural evolution from GSM and other second generation (2G)mobile systems. It provides interconnection with 2G networks as well as other terrestrial nd satellite-based networks.UMTS presents a unique opportunity to cater to the needs of individuals in the Information Society. As a multi-national, multi-sector system that supports numerous protocols and transport technologies, UMTS eliminates barriers that oneposed problems for communications and enables the creation and delivery of fully personalized communication services to both mass Limitations of 2G systems The limitations of 2G mobile systems such as GSM include: 1. congestion, There are more than 300 million wireless subscribers worldwide and thus a need to increase system capacity. 2. limited mobility around the world, 3. There is a need for global standardization. 4. limited services. 5. There is a need for new multimedia applications and services. Wideband - Code Division Multiple Access (WCDMA) WCDMA optimally divides the available radio spectrum on the air interface into a number of channels and defines how these channels are allocated to the many users accessing the network. WCDMA allows for variable bit rates and variable Quality of Service (QoS). WCDMA provides: 1. better spectrum efficiency, 2. wider coverage, 3. support for all types of services (circuit, packet and multimedia), 29
  • 30. 4. enhanced privacy, IP Multimedia subsystem (IMS) IMS (IP Multimedia Subsystem) enables and drives efficient converged service offerings. It is the key to delivering multimedia services with telecom-grade quality of service across fixed and mobile accesses. It creates new opportunities for operators who want to deliver attractive, easy-to-use, reliable and profitable multimedia services – including voice, pictures, text and video, or any combination of these –with existing services. Users benefit by being able to enjoy attractive converged multiple services regardless of access network and device. Service success is very much dependent on the ability of operators to create and deliver an experience that fulfills or exceeds users’ expectations. To maintain their position as service provider, operators need to climb up the value chain and take a more active part in service delivery. IMS is designed precisely for that purpose. IMS is access-independent: it is the only open standardized way to deliver IP-based consumer and enterprise services, enabled by one common core and control, to the fixed, mobile and cable communities. It combines the quality and interoperability of telecoms with the quick and innovative development of the Internet. IMS does this by making the unique values of the telecom industry easily available to the application development community.When implemented according to agreed standards, IMS enables operators to mix and match equipment and applications from multiple vendors, and enables mobile users to access their personal set of services wherever they roam, whichever operator network they are connected to. IMS includes the tools and functions needed to handle numerous non-standardized services in a standardized way – ensuring the interoperability, access awareness, policy support, charging, security and quality of service functionality required to meet consumer demand for attractive and convenient offerings. Why IMS? ‘Why IMS?’is one of the top strategic questions for any operator these days. There are many good answers, but perhaps the key one is that IMS delivers innovative multimedia services over fixed and mobile networks using open standards. IMS addresses key issues such as convergence, service creation and delivery, service interconnection and open standards. IMS can allow an operator to retain its existing business models, or evolve towards new ones. WIRELESS LAN & Bluetooth 30
  • 31. WIRELESS LAN INTRODUCTION Over recent years, the market for wireless communications has enjoyed tremendous growth. Wireless technology now reaches or is capable of reaching virtually every location on the face of the earth. Hundreds of millions of people exchange information every day using pagers, cellular telephones, and other wireless communication products. With tremendous success of wireless telephony and messaging services, it is hardly surprising that wireless communication is beginning to be applied to the realm of personal and business computing. No longer bound by the harnesses of wired networks, people will be able to access and share information on a global scale nearly anywhere they venture. This article will try to answer some basic questions of why and where wireless local area networks can be used, and present a brief description of some protocols that have been developed, with emphasis on IEEE 802.11. Mobile IP Mobile IP was suggested as a means to attain wireless networking. It focuses its attention at the Network Layer, working with the current version of the Internet Protocol (IP version 4). In this protocol, the IP address of the mobile machine does not change when it moves from a home network to a foreign network. In order to maintain connections between the mobile node and the rest of the network, a forwarding routine is implemented. When a person in the physical world moves, they let their home post office know to which remote post office their mail should be forwarded. When the person arrives at their new residence, they register with the new post office. This same operation happens in Mobile IP. When the mobile agent moves from its home network to a foreign (visited) network, the mobile agent tells a home agent on the home network to which foreign agent their packets should be forwarded. In addition, the mobile agent registers itself with that foreign agent on the foreign network. Thus the home agent forwarded all packets, intended for the mobile agent, to the foreign agent, foreign agent sends them to the mobile agent on the foreign network. When the mobile agent returns to its original network, it informs both agents (home and foreign) that the original configuration has been restored. No one on the outside networks need to know that the mobile agent moved. This configuration works, but it has some drawbacks. Depending on how far the mobile agent moves, there may need to be some store and forwarding of packets while the mobile agent is on neither the home nor the foreign network. In addition, Mobile IP works only for IPv4 and does not take advantage of the features of the newer IPv6. BLUETOOTH Introduction Bluetooth is an open standard and specification for small-form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices. The technology allows users to form wireless connections between various communication devices, in order to transmit real-time voice and data communications. It extends a new era of 31
  • 32. communication that eliminates and replaces cables which connects mobile phones, laptops, palmtops, desktops and printers. It provides an absolute synchronization between connecting devices. In February 1998, five companies as Bluetooth promoters - Ericsson, IBM, Intel, Nokia and Toshiba have organized and founded a group known as the Bluetooth SIG (Special Interest Group). The aim of this group is to study and develop a single standard for short range radio connectivity, ensuring interoperability between devices of different manufacturers. Since that time 3Com, Lucent, Microsoft, Motorola and more than 2000 member (adopters) companies have joined the organization. In July 1999 first version of the Bluetooth specification incorporating both radio protocols and control software was published. Concept The Bluetooth radio is built into a small microchip and operates in the 2.4Ghz band, a globally available frequency band ensuring communication compatibility worldwide. It uses frequency hopping spread spectrum, which changes its signal 1600 times per second, which helps to avoid interception by unauthorized parties. In addition software controls and identity coding built into each microchip ensure that only those units preset by their owners can communicate. The specification has two power levels defined; a lower power level that covers the shorter personal area within a room, and a higher power level that can cover a medium range, such as within a home. It supports both point-to-point and point-to-multipoint connections and provides up to 720 Kbps data transfer within a range of 10 meters (up to 100 meters with a power boost). The technology uses omni directional radio waves that can transmit through walls and other non-metal barriers. If there is interference from other devices, the transmission speed decreases but does not stop With the current specification, up to seven slave devices can be set to communicate with a master radio in one device. This connection of devices (slaves and master) is called a piconet. Several piconets can be linked together to form scatternets, which allow communication between other device configurations. Bluetooth range diagram is shown in figure 1. Frequency Hopping 32
  • 33. Bluetooth communicates on a frequency of 2.45 GHz (starting from 2.402 GHz and stopping at 2.480 GHz) , which has been set aside by international agreement for the use of industrial, scientific and medical devices (ISM). A number of devices that you may already use take advantage of this same radio-frequency band. Baby monitors, garage-door openers and the newest generation of cordless phones all make use of frequencies in the ISM band. Making sure that Bluetooth and these other devices don't interfere with one another has been a crucial part of the design process. Bluetooth devices will coexist in the same frequency as wireless LAN and microwave oven consequently the band has to be very robust. Each channel is 1 MHz wide and so there are 79 different channels. Spread spectrum technologies help to avoid interference between radio technologies. A Bluetooth device changes its frequency in a pseudo random way 1600times per second. Interference often occurs in a small portion of frequency band so hoping between different frequencies makes the channel insensitive. Corrupt packets are resent on another frequency on which the same interference may not exist. Packets are also small. A Bluetooth channel always consists of a master and one or more slaves. Master initiates the connection. The master decides on a hoping scheme that is related to its internal clock. The slave calculate an offset which is the difference between master and slave clocks, and uses this information to determine the frequency to which it will hop. This process enables the master and its slaves to hop to the same frequencies at all times. The uplink and downlink channels for one device are time multiplexed and use the Time Division Duplex and hence use the same frequency hoping scheme. Working Principle Bluetooth uses radio medium to link devices instead of physical cable medium.Bluetooth technology is hardware independent.For example, if a digital camera is to be connected to a laptop/desktop, a cable system is necessary which is compatible with both devices Each device follows a different set of interface/configuration to be connected.In the Bluetooth approach, the devices are Bluetooth enabled thus eliminating the interface/configuration conflict.This is true for all the hand-held devices which are communicating with each other in Bluetooth mode technology.This is possible by embedding a tiny inexpensive chip in a short-range transceiver into the mobile. Bluetooth enabled devices are connected in two different networks ‘A’ and ‘B’ Up to eight devices can be connected in a network.In order to communicate w with other devices, all devices should work on the same frequency. The device, which initiates the connection, is called ‘Master Device’ and the devices, which are connected to master device, are called ‘Slave Devices’ which are switched to the specified frequency for further communication. If a subscriber is trying to connect his services (known device), then the master device will send a ‘Page’ command which checks whether the device is within the range.If so, the communication is established. However, if an unknown device is trying to connect then the master device sends an ‘inquiry’ command and gets all the information about the unknown device and the database is updated.Thus, the devices within the 33
  • 34. network or from other networks talk with each other.As seen earlier, Master device sets hop sequence for the Slave devices on the network and controls whether or not each device is active or inactive within the network.Despite of Master/Slave designation, the network behaves more of peer to peer relation.Instead of one device designated to control and manage all resources. Each device has equal access to the entire network. A slave device in a network can establish connection to the other networks also.Thus, each slave device can participate with up to eight different networks. Application for End Users Bluetooth technology supports all multimedia applications used by end users.A few applications are as given below. 1. Provides an absolute synchronization among various digital devices (like mobile phone, desktop, laptop and PDA). 2. Bluetooth enabled mobile phone can be used as a mobile router placed in a suit case. 3. Internet surfing is possible from laptop from anywhere 4. Passing on print command remotely for printing jobs. Advantages of Bluetooth 1. Bluetooth provides flexible network that allows upto eight devices to share the information. 2. The network architecture allows one to add or remove nodes without additional infrastructure involved. 3. The size of the implementation is small. 4. Power consumption is low. 5. It has the support of the security considerations like ‘encryption’ Conclusion Bluetooth is going to emerge as one of the largest growing area in the field of telecommunications in providing device to device wireless connectivity.2This standard is now available for 2G networks and is in the process of evolution for 3G network standards tool. 34
  • 35. Broadband through WI FI and WIMAX WI FI Introduction Any two computers can be directly wired to each other using a crossover cable. When number of computer exceeds, cables must be run from each computer to another computer or to the central device. It can be time-consuming and difficult to run cables under the floor or through walls, especially when computers sit in different rooms. The correct cabling configuration for a wired LAN varies depending on the mix of devices, the type of Internet connection, and whether internal or external modems are used. Look around us at the moment, we have our keyboard connected to the computer, as well as a printer, mouse, monitor and so on. What (literally) joins all of these together?, they are connected by cables. Cables have become the bane of many offices. Most of us have experienced the 'joys' of trying to figure out what cable goes where, and getting tangled up in the details. Is there a technology to replace cable? Wireless is the answer. Wireless isn't just about the freedom to stay connected as we move around the office. It's also about the freedom to connect our mobile laptop PC to the Internet from any room in our home or whenever we take it on the road. Going wireless used to be complicated. It meant dealing with different wireless standards and all the resultant hardware and software. But the wireless industry settled on 802.11b (or Wi-Fi) as the predominant standard in 1999, sending prices downward as demand surged. Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for "Wireless Fidelity", is a set of product compatibility standards for wireless local area networks (WLAN). Wi-Fi was intended to be used for mobile devices and LANs, but is now often used for Internet and wireless VoIP phone access. It enables a person with a wireless-enabled computer, a personal digital assistant (PDA), or a wireless VoIP phone to connect to the Internet when in proximity of an access point The geographical region covered by one or several access points is called a hotspot. Wi-Fi is a trademark of the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance), the trade organization that tests and certifies equipment compliance with the 802.11x standards. Today WLAN technologies all follow one of the three main Wi-Fi communication standards. The benefits of wireless networking depend on the standard employed: 35
  • 36. 802.11b was the first standard to be widely used in WLANs. The 802.11a standard is faster but more expensive than 802.11b; 802.11a is more commonly found in business networks. The newest standard, 802.11g, attempts to combine the best of both 802.11a and 802.11b, though it too is more a more expensive home networking option. Difference between WI FI and WIMAX The main problem with WiFi access is that hot spots are very small, so coverage is sparse. Is there a new technology that would provide high speed of broadband service, Wireless rather than wired access, so it would be a lot less expensive than cable or DSL and much easier to extend to suburban and rural areas and Broad coverage like the cell phone network instead of the tiny little hotspots of WiFi. This technology is called WiMAX, short for Worldwide Interoperability for Microwave Access. The big difference between Wi-Fi and WiMAX is that we're going to use licensed spectrum to deliver WiMAX. To date, all Wi-Fi technology has been delivered in unlicensed spectrum. WiMAX will use one of the unlicensed frequencies, but we're also supporting two other frequencies that are licensed. What that means is that you can turn up the output power and broadcast longer distances. So where Wi-Fi is something that is measured in hundreds of feet, usually WiMAX will have a very good value proposition and bandwidth up to several miles. Also WiMAX is designed to be a carrier-grade technology, which requires a higher level of reliability and quality of service than are now available in typical Wi-Fi implementations. Those fundamental differences make WiMAX more of a metropolitan area access technology versus hotspot. Thus WiMAX has the potential to do to broadband Internet access what cell phones have done to phone access. In the same way that many people have given up their "land lines" in favor of cell phones, WiMAX could replace cable and DSL services, providing universal Internet access just about anywhere you go. WiMAX will also be as painless as WiFi -- turning your computer on will automatically connect you to the closest available WiMAX antenna. A WiMAX system consists of two parts: A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area -- as big as 3,000 square miles (~8,000 square km). A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today. A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link. This connection to a second tower (often referred to as a), along with the ability of a single tower to cover up to 3,000 square miles, is what allows WiMAX to provide coverage to remote rural areas. 36
  • 37. What this points out is that WiMAX actually can provide two forms of wireless service: WiFi-style access will be limited to a 4-to-6 mile radius (perhaps 25 square miles or 65 square km of coverage, which is similar in range to a cell-phone zone). Through the stronger line-of-sight antennas, the WiMAX transmitting station would send data to WiMAX-enabled computers or routers set up within the transmitter's 30-mile radius (3,600 square miles or 9,300 square km of coverage). This is what allows WiMAX to achieve its maximum range. WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30 m). WiMAX will blanket a radius of (50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter. Wi-Fi kind of lives by what we call the "five minute rule". If you live in a city, most likely you can walk five minutes and find a hotspot. Or if you're in your car in the suburbs or a village, you can usually drive within five minutes and find one of those. With WiMAX we're trying to offer that same type of service without having to drive or walk five minutes. Even though it's only five minutes, it's still five minutes.Eventually, you can just open your notebook and get a connection, wherever you may be. Wi-Fi is based on the IEEE 802.11 specifications. There are currently four deployed 802.11 variations: 802.11a, 802.11b, 802.11g, and 802.11n. Bluetooth uses Frequency Hop Spread Spectrum (FHSS) to avoid any interference. A Bluetooth channel is divided into time slots each 625 micro second in length. The devices hop through these timeslots making 1600 hops per second. This trades bandwidth efficiency for reliability, integrity and security. The range for Bluetooth communication is 0-30 feet (10 meters) with a power consumption of 0dBm (1mW). This distance can be increased to 100 meters by amplifying the power to 20dBm. The Bluetooth radio system is optimized for mobility. Bluetooth communication occurs between a master radio and a slave radio. Bluetooth radios are symmetric in that the same device may operate as a master and also the slave. Each radio has a 48-bit unique device address (BD_ADDR) that is fixed. Two or more radio devices together form ad-hoc networks called piconets. All units within a piconet share the same channel. Each piconet has one master device and one or more slaves. There may be up to seven active slaves at a time within a piconet. Thus, each active device within a piconet is identifiable by a 3-bit active device address. Beyond 3G Introduction 37
  • 38. Introduction New data services, interactive TV and evolving Internet behavior will influence mobile data usage. Long sessions in always-on mode will force a re-think of radio access technology to achieve the required but not easy to attain capacity (Gbit/s/km) at low cost. The ideas presented in this article can increase capacity by a factor of 500 with regard to expected cellular deployments. Coverage will be based on large umbrella cells (3G, WiMAX) and numerous Pico cells interconnected to provide the user with seamless high data rate (several Mbs) sessions. Scalable and progressive deployments are possible while protecting the operator’s long- term investment. The 4G infrastructure operator will mix several technologies, each of which has its optimal usage. The connection to one of them will result in a real-time trade-off which will offer the user the best possible service. Some tools that genuinely improve the user’s multimedia quality of experience (availability, response time, definition, etc) are also presented in this article. 4G MOBILE 4G will deliver low cost multi-megabit/s sessions any time, any place, using any terminal. Operational Excellence Voice was the driver for second generation mobile and has been a considerable success. Today, video and TV services are driving forward third generation (3G) deployment and in the future, low cost, high speed data will drive forward the fourth generation (4G) as short- range communication emerges. Service and application ubiquity, with a high degree of personalization and synchronization between various user appliances, will be another driver. At the same time, it is probable that the radio access network will evolve from a centralized architecture to a distributed one. Service Evolution The evolution from 3G to 4G will be driven by services that offer better quality (e.g. video and sound) thanks to greater bandwidth, more sophistication in the association of a large quantity of information, and improved personalization. Convergence with other network (enterprise,fixed) services will come about through the high session data rate. It will require an always-on connection and a revenue model based on a fixed monthly fee. The impact on network capcity is expected to be significant. Machine-to-machine transmission will involve two basic equipment types: 38
  • 39. 1. sensors (which measure parameters) 2. tags (which are generally read/write equipment) It is expected that users will require high data rates, similar to those on fixed networks, for data and streaming applications. Mobile terminal usage (laptops, Personal digital assistants, hand-helds) is expected to grow rapidly as they become more user friendly. Fluid high quality video and network reactivity are important user requirements. 4G MOBILE Some of the key technologies required for 4G are briefly described below: GPRS BASIC Introduction The General Packet Radio System (GPRS) provides actual packet radio access for Global System for Mobile Communications (GSM) and time-division multiple access (TDMA) users. The main benefits of GPRS are that it reserves radio resources only when there is data to send and it reduces reliance on traditional circuit-switched network elements. GPRS GPRS is a data service for GSM, the European standard digital cellular service. It is a packet- switched mobile data service, a wireless packet based network. GPRS, further enhancing GSM networks to carry data, is also an important component in the GSM evolution entitled GSM+. High-speed mobile data usage is enabled with GPRS. 39
  • 40. IF GPRS is compared to GSM data services, the following applies: In GSM all the data that has to be sent, is sent via a circuit switched connection. This means, that a link has to be established and is used and maintained from setup until release. The data is sent via one physical timeslot and has a maximum data rate of 9.6 kbps. In GPRS all the data that has to be sent, is split into several smaller data packets first. Those packets are then sent individually across the GPRS network and each of those packets can travel on a different route. The packets arrive at the right destination address and could be reassembled in the right order, because every single packet contains the destination address and information about the sequencing of the different packets. In GPRS, one user can occupy more than one timeslot or more than one user can be on a single timeslot. Depending on different aspects, a maximum data rate of 171.2 kbps could be achieved. For GPRS the ETSI Standard introduces two new elements, the Serving GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN) (Shown in the diagram below as shadowed objects) is introduced to create an end-to-end packet transfer mode. The HLR is enhanced with GPRS subscriber data and routing information. Two services are provided; Point -To-Point(PTP) Point-To-Multipoint (PTM) (not yet specified by the Standards) The European Telecommunications Standards Institute (ETSI) has specified GPRS as an overlay to the existing GSM network to provide packet data services. In order to operate a GPRS service over a GSM network, new functionality has to be introduced into existing GSM network elements and new network elements have to be integrated into the existing operators GSM networks.The Base Station Subsystem (BSS) of GSM has to be upgraded to support GPRS. The BSS works with the GPRS Support Node (GSN) to provide GPRS service in a similar manner to its interaction with the Switching subsystem for the circuit switched services. DIGITAL SUBSCRIBER LOOP 40
  • 41. The Digital Subscriber Line (DSL) technology is widely regarded as a vehicle for offering wired broadband services to the mass market. The services include high-speed access to the Internet, voice and telephony services, interactive video services, e-commerce, messaging, alerting and other multimedia services. Success of the Internet and the World Wide Web has created the market demand and high expectations for high-speed data services through DSL Twisted pair - voice Twisted pair - voice and data It uses the existing copper pair for providing Broadband. The previous diagram showed how the twisted pair is used for transmitting voice and data. The DSL technology is now mature, poised for rapid deployment and industry growth in the near future. There are number of DSL types available to address the various network environments and applications in the light of trade-offs between rate and reach 1. HDSL -- High-rate DSL 2. ADSL-- Asymmetric DSL 41
  • 42. 3. SDSL – Symmetric DSL 4. RADSL – Rate Adaptive DSL ADSL (Asymmetric Digital Subscriber Line) Asymmetric Digital Subscriber Line (ADSL) technology was first introduced in 1992 as a system capable of delivering Video-on- Demand (VoD) service over telephone networks. ADSL utilizes the same twisted two-wire facility (called the subscriber loop) as the traditional telephone service. The traditional telephone service is often referred to as “Plain Old Telephone Service” or POTS. With the initial system architecture and design of ADSL, the same twisted pair could simultaneously support both POTS and data. This is made possible due to a frequency multiplexing technique that supports POTS in the base band and data in a high frequency band above the telephone service. The ADSL data service is asymmetrical, in that, it has a higher downstream data rate (up to 6 Mbps towards the subscriber) than the upstream data rate (up to 640 kbps towards the service provider). The main objective is to use ADSL as a technology choice for offering VoD service. In 1994 it was proved that ADSL technology could be used to offer high speed data services including video. (Click to view flash movie on speed comparison). Mass-market success of the Internet technologies – World Wide Web, the Internet browser, and the Universal Resource Locator (URL) led to high residential as well as business demand for broadband services. SDSL(Symmetric DSL) A variation of ADSL technology more suitable for the T1/E1 market was envisioned via a symmetric offering of ADSL, known as SDSL. The SDSL technology was envisioned to be a 2-wire equivalent to the 4-wire HDSL service. The market expectations were Ubiquitous and consistent high-speed data offering, support for internet access protocols, automated provisioning, dynamic access to services without requiring telephone company intervention, and inexpensive pricing to enable a wider deployment of service. Note that all of these expectations have shifted from service provider ADSL ARCHITECTURE 42
  • 43. In POTS, with the available voice band of 3.5kHz and allowed S/N = 30dB, the theoretical upper limit on data rate will be roughly 35Kbps. Copper access lines can pass frequencies into the MHz region. This feature is precisely what ADSL focuses on. ADSL technology offers the asymmetric bandwidth characteristics that are 1.544-8.448Mb/s in downstream and 32- 768kb/s in the upstream. This feature fits in with the requirements of client-server applications, in which the client typically receives much more data from the server then he is able to generate ADSL System Architecture The ADSL functions at the network end (central office end) are performed by an ADSL Terminal Unit-Central office type (ATU-C) together with a splitter function (S-C). The ATU-C interfaces with the network switching, transport, and multiplexing functions and network operations. The ATU-C functions are usually integrated within a higher level network element, e.g. DSL access multiplexer (DSLAM). Although copper pairs are widely available, several line conditions may prevent the delivery of ADSL: first, if the telephone line to the customer premises is longer than 5.5km, second, existing of the load coils or an excessive number of bridged taps and third, that some portions of the telephone line is carried to the premises on fiber optic cable . DSLAM contains the access interface (network termination – NT) to the appropriate next device in the network, e.g., Tier2, Tier1 Switch etc. ADSL functions at the customer end (remote end) are performed by an ADSL Terminal Unit-Remote end type (ATU-R) together with a splitter function (S-R). At the customer premises, ATU-R may present the interfaces to the local distribution for broadband services via service modules (SM). The SM contains necessary decoders and terminal interfaces for the given service and customer control interfaces. Splitters are three node devices that allow the telephony signals and the ADSL signal to reside on the same copper loop without interfering one with the other. The splitter provides a low pass filter to the basic voice and control telephony signal (below 4 kHz) and a high pass filter for the ADSL signals, starting approximately at 25 kHz or above. Most POTS splitter designs are passive, that is without powering requirements. The advantages of passive filters are in their reliability, because they enable continuous telephone service even if the modem fails (for example, due to a power outage). 43
  • 44. The connectivity architecture of DSLAMs is as shown in figure. The DSLAMs are connected to the Tier 2 Switches and again, the Tier2 switches are connected to Tier1 Switch. In turn the Tier1 Switch is connected to "Broadband Remote Access Server"(BBRAS) which is routed to core router through which it gets access to the International Gateway. The below diagram shows the connectivity portion of DSLAM with the Tier2 switch. If the distance between the DSLAM and the Tier2 switch is less than 10 Kms, then Dark Fibre could be used for connectivity. (Dark fibre means a spare fibre). If the distance exceeds 10 kms, then we can use the STM medium with electrical to optical converters at both the ends, as both DSLAM as well as Tier2 switch has optical interface whereas the output from STM is electrical. There are a large number of different kinds of servers that can be accessed by an ADSL system Video on Demand service is one of the most interesting aspect of ADSL. By using MPEG coded video it is possible to deliver video quality movies over existing copper loops to customers. A video quality can be achieved by only 1.5 Mbps data rate. Together with pure VoD services there might exist combined movie information and advertiser services in which commercial and non commercial information that providers and advertisers can 44
  • 45. deliver their information. Full-rate ADSL: The downstream uses DMT tones 7 - 255 (echo cancellation) or 32 - 255 (FDM). The upstream channel uses tones 7 - 31. Bit loading is adaptive and varies from 2 to 15 bits per tone (sub channel) depending on the relative noise of each carrier. When high noise levels are detected in a given sub channel, the DMT modem can shut down a particular sub channel altogether. ADSL MODEM The ADSL transmission signal is modulated onto discrete multi- tones (DMT). As already seen, there are 256 independent parallel sub channels available in the 1.1MHz ADSL bandwidth. Each sub channel is separated by approximately 4 kHz and has a distinct carrier frequency in the center of this 4 kHz band. While DMT is the physical transmission level, framing and encoding (error correction) occurs at a higher level. The modulation technique used in each of the discrete multi-tone (DMT) channels is Quadrature Amplitude Modulation (QAM) where both the phase angle and the amplitude of the carrier band are modulated to represent the information being transmitted. In a typical ADSL modem, the main sections are 1. The Digital Interface (e.g. ATM) 2. The Framer/FEC plus Encoder/Decoder 3. The DMT Modulator 4. The AFE (Analog Front End) The Framer multiplexes serial data into frames, generates FEC (Forward Error Correction), and interleaves data. FEC and data interleaving corrects for burst errors. This allows DMT-based ADSL technology to be suitable for support of MPEG-2 and other digital video compression techniques For the transmit signal 45
  • 46. The Encoder encodes frames to produce the constellation data for the DMT Modulator. It assigns the maximum number of bits per tone (based on measured SNR of each carrier) and generates a QAM constellation where each point represents a digital value. Each constellation point is one of N complex numbers, x + iy, where x and y are the phase and amplitude components. The summation of bits in all carriers, multiplied by the frame rate (4kHz), represents the data rate For the receive signal The Decoder converts QAM symbols back into the data bit stream. In the DMT Modulator, a frequency domain processor implements FFT/IFFT and associated processing. In the transmit path, the Inverse Fast Fourier Transform (IFFT) module accepts input as a vector of N QAM constellation points and duplicates each carrier with its conjugate counterpart so the 2N output samples are real. The 2N time domain samples have the last 2N/16 samples appended as a cyclic prefix, and are then delivered to the DAC (Digital to Analog converter). The set of time domain samples represents a summation of all the modulated sub channels, for the duration of one data frame NGN BASIC CONCEPTS Definition & Features of NGN 46
  • 47. BSNL's Plan 1. Tender for 200 KC IP TAX equipment, which is Pilot Project for introduction of NGN in transit network, has been awarded 2. Plan to introduce 6.4 million circuits capacity in 2007-2008 through IP TAX 47
  • 48. 3. Strengthen SSTP Networks 4. Trials for migration of PSTN access to NGN and for introduction of NGN in access network underway 5. Migration to IMS expected to roll out from 2009 6. Full migration to NGN with replacement of PSTN by 2012 7. IP Multimedia Subsystems 8. WiMax-Access to NGN 9. WHAT IS NGN? 10. NGN is a network infrastructure that will enable the provisioning of the existing telecommunications services and innovative applications of the next generation. It is a converged network capable of carrying voice, data and video over the same physical network, with all traffic carried as IP (Internet Protocol).NGN is a multi-service network , which enables operators to implement converged and new services in addition to POTS. From the users’ perspective, the convergence of services will enable the “desired” services from any type of access network. 11. NGN i.e. the Next Generation Network refers to the convergence of different telecom services i.e. voice, data and video over a unified packet network utilising Internet 48
  • 49. Protocol (IP). NGN can be thought of as a packet-based network where the packet switching and transport elements (e.g. routers, switches and gateways ) are logically and physically separated from the service/ call control intelligence. This control intelligence is used to support all types of services over the packet-based transport network including everything from the basic voice telephony services to data, video, multimedia, advanced broadband ARCHITECTURE OF NGN The architecture of Next Generation Network is shown below. It is a horizontally layered network architecture instead of the present vertically separated networks for each service.It uses packet- based transport for all services (including voice).The access, switching, transport, control and service functions which are integrated in today’s switches are separated into individual network layers, which inter-work via interfaces based on open standards.The most significant aspect is the separation of call control from switching and transport functions NGN APPLICATIONS – THE KEY TO 49
  • 50. COMPETITIVE DIFFERENTIATION 1. Voice Telephony NGNs will likely need to support various existing voice telephony services (e.g., Call Waiting, Call Forwarding, 3-Way Calling, various AIN features, various Centrex features, and various CLASS features).Note, however, that NGNs are not trying to duplicate each and every traditional voice telephony service currently offered. Rather, they will likely attempt to support only a small percentage of these traditional services, with an initial focus on the most marketable voice telephony features and the features required from a regulatory perspective. 2. Data (Connectivity) Services Allows for the real-time establishment of connectivity between endpoints, along with various value-added features (e.g., bandwidth-on-demand, connection reliability/resilient Switched Virtual Connections [SVCs], and bandwidth management/call admission control). 1. Multimedia Services Allows multiple parties to interact using voice, video, and/or data. This allows customers to converse with each other while displaying visual information. 2. Virtual Private Networks (VPNs) Voice VPNs improve the inter location networking capabilities of businesses by allowing large, geographically dispersed organizations to combine their existing private networks with portions of the PSTN, thus providing subscribers with uniform dialing capabilities.Data VPNs provide added security and networking features that allow customers to use a shared IP network as a VPN. 1. Unified Messaging Supports the delivery of voice mail, email, fax, and pages through common interfaces. Through such interfaces, users will access, as well as be notified of, various message types (voice mail, email, fax , etc.), independent of the means of access (i.e., wire line or mobile phone, computer, or wireless data device). 1. Call Center Services 50
  • 51. A subscriber could place a call to a call center agent by clicking on a Web page.The call could be routed to an appropriate agent, who could be located anywhere, even at home (i.e., virtual call centers).Voice calls and e-mail messages could be queued uniformly for the agents.Agents would have electronic access to customer, catalog, stock, and ordering information, which could be transmitted back and forth between the customer and the agent. 1. Interactive gaming Offers consumers a way to meet online and establish interactive gaming sessions (e.g., video games). 2. Home Manager With the advent of in-home networking and intelligent appliances, these services could monitor and control home security systems, energy systems, home entertainment systems, and other home appliances IP Multimedia subsystem (IMS) IMS (IP Multimedia Subsystem) enables and drives efficient converged service offerings. It is the key to delivering multimedia services with telecom-grade quality of service across fixed and mobile accesses. It creates new opportunities for operators who want to deliver attractive, easy-to-use, reliable and profitable multimedia services – including voice, pictures, text and video, or any combination of these –with existing services. Users benefit by being able to enjoy attractive converged multiple services regardless of access network and device.pService success is very much dependent on the ability of operators to create and deliver an experience that fulfills or exceeds users’ expectations.. IMS is designed precisely for that purpose. IMS is access-independent: it is the only open standardized way to deliver IP-based consumer and enterprise services, enabled by one common core and control, to the fixed, mobile and cable communities. It combines the quality and interoperability of telecoms with the quick and innovative development of the Internet. IMS does this by making the unique values of the telecom industry easily available to the application development community.When implemented according to agreed standards, IMS enables 51
  • 52. operators to mix and match equipment and applications from multiple vendors, and enables mobile users to access their personal set of services wherever they roam, whichever operator network they are connected to. IMS includes the tools and functions needed to handle numerous non-standardized services in a standardized way – ensuring the interoperability, access awareness, policy support, charging, security and quality of service functionality required to meet consumer demand for attractive and convenient offerings. IMS offers a standardized way to deliver convenient IP-based consumer and enterprise services to fixed, mobile and cable community – enabled by one common core and control. It is the cornerstone of the evolution of current networks to a single, all-IP based network where all types of services (messaging, telephony, etc.) and media (voice, video, pictures, text etc.) can be integrated into a single user experience. For consumer, IMS opens communication options that seamlessly combine ongoing voice sessions with multimedia elements (sharing video while talking, for example) or enrich shared applications with voice communication (for instance, talking while playing a multiplayer game). WIRELESS TECHNOLOGY Wireless broadband technology sends data over a 'wireless' communications network, typically using radio frequency. These technologies are a strong and popular platform for delivery of high-speed Internet services and wireless broadband, is emerging as a legitimate local access platform for the delivery of high-quality digital data, video and voice services. In many regional areas where telecommunications infrastructure such as fibre optic or coaxial cable is limited, wireless technologies offer a competitive broadband access solution.Rather than stringing thousands of miles of fiber, coax or twisted-pair wiring, a wireless operator installs a headend and transmission tower and is open for business. Wireless technologies can provide area coverage from anywhere between 5km to 40km depending on the local terrain and strength of the transmitter signal. The advantages of wireless broadband: 1. Access - a wireless network provides high-speed access to the Internet without the need for expensive wire or cable infrastructure. 52
  • 53. 2. Flexibility - the capacity (number of customers) of a wireless network can be expanded when required. 3. Versatility - wireless services are suitable for both lightly populated areas, but can also be deployed to provide customised services in highly populated areas. 4. Costs - without the need for expensive equipment and/or infrastructure, the cost of wireless broadband products can be lower than wired products. Wi-Fi Short for wireless fidelity, Wi-Fi technologies include the approved IEEE 802.11a, b and g specifications, as well as the yet-to-be-ratified 802.11n specification. Wi-Fi is the first high-speed wireless technology to enjoy broad deployment, most notably in hotspots around the world including homes and offices, and increasingly cafes, hotels, and airports. Wi-Fi hotspots became popular almost immediately and have been applauded by road warriors for their ability to improve productivity. Wi-Fi is limited, however, by its range: high-speed connectivity is possible only as long as a user remains within range of the wireless access point, which is optimum within 300 feet. Wi-Fi was one of the earliest high-speed wireless data technologies and now benefits from a broad availability of supporting products and technologies. Some of the newest platforms even support multiple Wi-Fi standards (e.g. 802.11a, b and/or g) for compatibility among several wireless networks. WiMAX WiMAX is an emerging technology that will deliver last mile broadband connectivity in a larger geographic area than Wi-Fi, enabling T1 type service to business customers and cable/DSL-equivalent access to residential users. Providing canopies of coverage anywhere from one to six miles wide (depending on multiple variables), WiMAX will enable greater mobility for high-speed data applications. With such range and high throughput, WiMAX is capable of delivering backhaul for carrier infrastructure, enterprise campuses and Wi-Fi hotspots. 53
  • 54. WiMAX will be deployed in three phases. Phase one will see WiMAX technology using the IEEE 802.16d specification deployed via outdoor antennas that target known subscribers in a fixed location. Phase two will roll out indoor antennas, broadening the appeal of WiMAX technology to carriers seeking simplified installation at user sites. Phase three will launch the IEEE 802.16e specification, in which WiMAX-Certified* hardware will be available in portable solutions for users who want to roam within a service area, enabling more persistent connectivity akin to Wi-Fi capabilities today. CABLE MODEM BASICS Current Internet access via a 28.8–, 33.6–, or 56–kbps modem is referred to as voiceband modem technology. Like voiceband modems, cable modems modulate and demodulate data signals. However, cable modems incorporate more functionality suitable for today's high-speed Internet services. Cable modem is capable of delivering up to 30 to 40 Mbps of data this is approximately 500 times faster than a 56–kbps modem In the conventional case the TV set receives the signal directly from the cable operator through Co-axial cable as shown in the figure1. When internet data combined with the TV signal is received a splitter is required to separate the signals(figure 2). FIGURE 1 FIGURE CABLE MODEM BASICS FIGURE 1 FIGURE 2 54
  • 55. The separated data is taken through co-axial cable to the cable-modem which in turn is connected to the PC through Ethernet/USB port A subscriber can continue to receive cable television service while simultaneously receiving data on cable modems to be delivered to a personal computer (PC) with the help of a simple one-to-two splitter A device called a cable modem termination system (CMTS), located at the local cable operator's network hub, controls access to cable modems on the network.It is for support of data services that integrates upstream and downstream communication over a cable data network. The number of upstream and downstream channels in a given CMTS can be engineered based on serving area, number of users, data rates offered to each user, and available spectrum A cable headend (combiner)combines the downstream data channels with the video, pay-per-view, audio, and local advertiser programs that are received by television subscribers. The combined signal is then transmitted throughout the cable distribution network. Traffic is routed from the CMTS to the backbone of a cable Internet service provider (ISP), such as Road Runner, which, in turn, connects to the Internet. With newer cable modem systems, all traffic from the CMTS to the cable modem is encrypted to ensure privacy and security for users To try to promote cable modem rollouts, as well as relieve technological confusion, CableLabs, an industry trade organization, drafted a standard for cable modem products in 1996 called DOCSIS (Data Over Cable Service Interface Specification). The standard was developed to ensure that cable modem equipment built by a variety of manufacturers is compatible, as dial-up modems are. Today, CableLabs continues to manage a rigorous testing process for DOCSIS cable modems, stamping the products that 55
  • 56. POINT TO POINT PROTOCOL OVER ETHERNET(PPPOE) Point-to-Point Protocol over Ethernet is a proposal specifying how a host personal computer (PC) interacts with a broadband modem (i.e. xDSL, cable, wireless, etc) to achieve access to the growing number of High-speed data networks. Relying on two widely accepted standards, Ethernet and the point-to-point protocol (PPP), the PPPoE implementation requires virtually no more knowledge on the part of the end user other than that required for standard Dial up Internet access. In addition, PPPoE requires no major changes in the operational model for Internet Service Providers (ISPs) and carriers. The significance of PPP over Ethernet has to do with its far greater ease of use versus competing approaches. By making high-speed access easier to use for end consumers, and more seamless to integrate into the existing infrastructure for carriers and ISPs, PPPoE could speed the widespread adoption of High-speed access services Also, PPP over Ethernet provides a major advantage for service providers by maximizing integration with - and minimizing disruption of - service providers' existing dial network infrastructures. Through tight integration with existing back office automation tools that ISPs have developed for dial customers, PPPoE enables rapid service deployment and cost savings. From authentication, accounting and secure access to configuration management, PPPoE supports a broad range of existing applications and services. Why would PPPoE be used? PPPoE is used to allow Internet Service Providers (ISPs) the use of their existing Radius authentication systems from their Dial-Up service on a Broadband / Ethernet based service. Dial-Up is PPP; most broadband connections are Ethernet, hence Point to Point Protocol over Ethernet. It also allows for ISPs to resell the same line multiple times. IE: Rated services, Broadband specific content (movies, etc.), metered services, etc 1. ADSL modem, splitter Customer Premises – Connectivity 56
  • 57. Customer Premises - Connectivity ADSL-Configuration 57
  • 58. 1. Unzip the zipped RASPPPoE folder to a temp directory of your choice 2. Right click on "Network Neighborhood" (in ME "My Network Places"). Choose "Properties" Click "Add..." 3. Select "Protocol". Click "Add..." . Select "Have Disk". .Select "Browse" Then choose the folder you unpacked the RASPPPoE programs to. Then select any one of the INF files, it does not matter which one Click "OK“. Then "OK" again 4. In the "Select Network Protocol" window make sure "PPP over Ethernet Protocol" is highlighted and click "OK". .Click "OK" on "Network" window. Click "Yes" to Reboot. 5. Go to your "Start" menu, and then choose "Run". Type in RASPPPoE and click "OK“ "RASPPPoE" window opens. Click Exit 6. Double click the Dial-Up short cut on your desk top 7. Enter your userid as provided by your ISP Note: you may need to include your ISP's domain as part of your userid : INTRODUCTION TO MULTIPLAY The term meaning the provisioning of different telecommunication services by Telecom Service Providers on wired and wireless networks , such as Broadband Internet access, TV,VOD, VPN, Telephony/VOIP and mobile phone service. Broadband Multi-Play network focuses on the augmentation of Broadband Access Network supporting multi-play services like Video on Demand, IP TV, VoIP, VPN service etc with guaranteed control of 58
  • 59. critical parameters like latency, throughput, jitter to ensure high grade delivery of real time, near real time, non real time and best effort services. MULTIPLAY NETWORK The Multiplay network is a three tier Architecture consisting of the Access Network, Aggregation Network and Core & Content Delivery Network. BROADBAND NETWORK GATEWAY The Redback SmartEdge 800 Multi-Service Edge Router is deployed as Broadband Network Gateway (BNG) in BSNL Multi Play project. BNG act as Gateway of the broadband traffic towards the MPLS core. SmartEdge MSERs provide a comprehensive IP routing foundation required for the evolving Multi-Play broadband services. SmartEdge 800 MSER offers a diverse range of interface options: Ethernet, Packet over SONET (PoS) and channelized connections. All SmartEdge MSER interface modules are hot-swappable and highly resilient with full session and state redundancy in the event of a failure or replacement. Support for high-performance multicast is provided, including protocol independent multicasting (PIM), Internet group management protocol (IGMP) and multicast routing. 59
  • 60. 1. Session level reliability: Supports Non Stop Forwarding and keeps SubscribeSessions running uninterrupted during a Route Processor fail-over. 2. Resilient software architecture: Modular design provides stability and protects against crashes and protocol errors. 3. Carrier-Grade Design: Engineered to carrier standards and deployed in carrier networks worldwide. Network Connectivity Diagram The network connectivity of aggregation networks of various cities are illustrated in the following diagrams. Broadband Multiplay – A1 & A2 Cities The network connectivity of aggregation networks of A3 and A4 cities is shown below. Broadband Multiplay – A3 & A4 Cities 60
  • 61. MULTIPLAY SERVICES The Various services offered by Multiplay are as follows: 1. Internet Services 2. Layer3 VPN Services 3. Video Services 4. IP Telephony Services 5. Data/Voice/Video Services The network path and the traffic flow of various services are explained in the following section. FIBER TO THE HOME – FTTH Fiber to the home (FTTH) is the ideal fiber-optics architecture. In this architecture, fiber deployment is carried all the way to the customer’s home (premises).This chapter will address the solution, which is a fiber-optics architecture called FTTH FTTH has been developed in response to several residential access market drivers, including the following: 1. The Internet explosion, second line growth, the desire for higher speeds, alternative strategies such as voice over DSL (VoDSL), voice over IP (VoIP), voice over ATM (VoATM), and cable modems 2. The increased competition in the market due to the growing number of competitive local-exchange carriers (CLECs), an increase in services offered by application service providers (ASPs), and deregulation and pending Federal Communications Commission (FCC) rulings 61
  • 62. 3. The declining costs of optical equipment Technology Fiber To The Home – FTTH How FTTH works In an FTTH system, equipment at the head end or CO is interfaced into the public switched telephone network (PSTN) and is connected to ATM or Ethernet interfaces. Video services enter the system from the cable television (CATV) head end or from a satellite feed. SMPS A switched-mode power supply, switch-mode power supply, or SMPS, is an electronic power supply unit (PSU) that incorporates a switching regulator — an internal control circuit that switches power transistors (such as MOSFETs) rapidly on and off in order to stabilize the output voltage or current. Switching regulators are used as replacements for the linear regulators when higher efficiency, smaller size or lighter weight are required. They are, however, more complicated and their switching currents can cause noise problems if not carefully suppressed. As with any offline electronic systems employing peak-hold AC-DC conversion, simple SMPS designs may have a poor power factor. The power output to cost crossover point between SMPS and linear regulating alternatives has been falling since the early 1980s as SMPS technology was developed and integrated into dedicated silicon chips. In early 2006 even very low power linear regulators became more expensive than SMPS when the cost of copper and iron used in the transformers increased abruptly on world markets. 62
  • 63. Basic Concepts Power plant is an equipment, which gives uninterrupted DC power supply to the telecommunication systems. Because telecommunication systems require electrical energy for 1. Conversion of speech signals to electrical signals 2. For operating switching, transmission equipments Need of D.C. Power supply 1. Harmonics of A.C may affect the speech signals. 2. Relays used in telecom systems are more sensitive to D.C than A.C 3. Transistors and I.C.s etc. being unidirectional devices, the use of D.C has become necessary. 4. Arranging standby source to A.C is difficult compare to D.C for which secondary cells can be used as S/B source. 5. Not hazardous to human life Basic Concepts Sources of power: Telecommunication systems need uninterrupted power supply round the clock and throughout the year. For any uninterrupted power supply system, two sources are required. 1. Normal or Main source Main Source is D.C derived from commercial source. 2. Secondary or standby source Secondary cells By name we can define Normal source is one which supplies power to the load round the clock and secondary source is one which supplies power to the load only during the absence of power from normal source. Hence it is a must to convert AC from commercial mains to D.C. Basic Concepts A.C to D.C conversions Previously M.G (Motor-Generator) sets were used for A.C to D.C conversion. In this A.C motor rotates on commercial A.C. supply. To the shaft of this AC motor, D.C. 63
  • 64. Generator will be coupled which generates D.C. Now a days static rectifiers using static electronic components like metal or diode rectifiers are used. Float Working Parallel Battery Float Scheme In this scheme two sets of Batteries (24 cells each set) are connected in parallel to the output of the rectifier. The output of the rectifier is 51.5 V. Hence floating voltage of each cell is 51.5 divided by 24 = 2.15V/ cell. Hence always 90% of battery capacity will be available for emergency usage For the operation of the scheme "POWER PLANT" is designed by TRC (Telecom Research Centre). Float Working Operating voltage: Now a days almost all of our telecom equipment works on -48 volts D.C. supply i.e. positive lead is earthed. Earthing of one pole of D.C: Reasons for earthing of one pole of D.C are as follows: 1. Switching can be single pole. 2. Cross talk and other disturbances can be avoided. 3. To make the alarm and supervisory system easy. 4. Earth return signaling can be used. Float Working Reasons for earthing positive pole of D.C 64
  • 65. 1. In electrolysis positive electrode will be normally corroded. If we keep our lines and equipment at negative potential, we can minimise troubles from the corrosive effects. 2. Partial Earth faults can be definitely identified if the conductor is negative. Otherwise fault is liable to seal up owing to oxidation. Power plant consists of 1. Float rectifier 2. Battery Charger 3. Switching Cubicle. Float Rectifier The function of the Float Rectifier is to receive three phase 440 V AC and to give a constant 51.5 Volts D.C without AC ripples. The steps involved to achieve the function are 1. Step-down 2. Rectification 3. Filtering 4. Regulation. Step down Transformer steps down the 3 phase A.C voltage from 440 volts to around 80 volts. Rectification Any unidirectional device rectifies the AC to DC. Here Diodes.SCRs are used for rectification Float Rectifier Filtering: Here multi-stage L.C. Filters are used for filtering the A.C. Ripples. Regulation: As far as Float Rectifier is concerned, Regulation is the mechanism by which the output of a float rectifier is kept constant at 51.5± 0.5V irrespective of input voltage variations of 12%, Output load variations of 5% to 105% and input frequency variations of 4% or 48-52 Hz. Why Regulation is required? 65
  • 66. Float rectifier should not only supply power to the load but also takes care of its battery sets, which are floated across its output. If the float rectifier output voltage is 51.5v, the cells are floated at 2.15v/cell and hence they are continuously trickle charged and this compensates losses due to self-discharge or local action. If FR output is 49.2V, the battery set is not trickle charged, hence trickle charging is to be given once in a fortnight. If FR output is less than 49.0V, the battery starts discharging. If FR output is greater than 51.5V, the floating voltage of each cell will be greater than 2.15V and the battery will be over charged. SMPS POWER PLANT (ITI MAKE) (Suitable for VRLA Batteries with 100A SMPS Rectifier Modules) Introduction The power system is intended primarily to provide uninterrupted DC power to Telecom equipments and current for charging the batteries in the presence of AC Mains. The system works from commercial AC mains which is rectified and regulated to -50V DC and is fed to the equipment (exchange). The system has provision to connect three sets of VRLA batteries and facility to charge them simultaneously to ensure that uninterrupted DC power supply is always available to the exchange. SMPS POWER PLANT (ITI MAKE) Technical Specification: For Module 1. Input Voltage 1. 320V to 480V r m s three phase (Nominal Voltage - 400V). 2. Frequency: 45 Hz. 65 Hz. 2. Output Voltage 1. Float mode 1. Nominal voltage : -54.0 + 0.5V, 2. Adjustment range : -48.0 to -56.0 V 2. Charge mode Voltage : -55.2 + 0.5 V SMPS POWER PLANT (ITI MAKE) 1. Rated current :100 Amps. 2. Psophometric noise : 66
  • 67. 1. Less than4 mV without battery floated. 2. Less than2 mV with battery floated. 3. Input power factor : Greater than 0.95 lag with 25% to 100% load at nominal input. 4. Efficiency : Greater than 90% at full Load and nominal input. 5. Protection : 1. Short-circuit protection. 2. Input over/under voltage protection. 3. Output over voltage protection. 4. Constant current features settable from 80 Amps. to 110 Amps. in auto float/charge mode. 1. Alarms and indicating lamps: 1. FR/BC on Auto Float/Charge : Green LED 2. Rectifier module over voltage : Red LED 3. DC output fail/Under voltage : Red LED 4. FR/BC Over Load (Voltage Drop) : Amber/Yellow LED SDH Content Snippets Modules 67
  • 68.  Digital Transmission  Disadvantages of PDH  Advantages of SDH and More.... The objective of this session also includes to enhance knowledge on 1. Fundamentals 2. Multiplexing 3. Network Elements 4. Network Topology 5. Telecom Management Networks 6. Network Management 7. SDH Measurements 8. SDH Frame and reliability of a digital network. Standards of PDH 68
  • 69. Disadvantages of PDH No common Standard 1. There are different hierarchies in use around the world. 2. Specialized interface equipment is required to inter-work the two hierarchies. 3. There is no standardized definition of PDH bit rates greater than 140 Mbit/s. 1. . Advantages of SDH Simplified add & drop function Compared with the older PDH system, it is much easier to extract and insert low-bit rate channels from or into the high-speed bit streams in SDH. It is no longer necessary to de-multiplex and then re-multiplex the plesiochronous struct BASIC DEFINITIONS of SDH Synchronous Transport Module This is the information structure used to support information pay load and over head information field organised in a block frame structure which repeats every 125 micro seconds. SDH NETWORK TOPOLOGY NETWORK TOPOLOGY The various network topologies in SDH are as follows: 69
  • 70. 1. Point-to-point link 2. Bus Topology 3. Ring Topology 1. Collapsed ring 2. Nested ring 4. Hub Topology 5. Star Topology 6. Mesh Topology 7. Mesh and Ring Topology Having identified and explained the current set of network building blocks, we will now look at the various methods of constructing SDH networks in practice. Initially, SDH technology will be deployed in new installations and then to replace or upgrade existing systems when they reach maximum capacity. At the simplest level, new point-to-point systems will use SDH Terminal muxes with the ability to expand to more complex SDH constructions later. We will now examine each possible topology in turn. SDH NETWORK TOPOLOGY Point to Point SDH Line Systems are natural successors to the 140 Mb/s and 565 Mb/s line systems currently deployed in backbone networks. In new installations, these PDH capacities will commonly be replaced by STM-4 (622 Mb/s) line systems. Increasingly, STM-16 (2.4 Gb/s) line systems will be required to cater for the ever increasing bandwidth requirements of backbone networks. Point to Point 70
  • 71. Point-To-Point Point-To-Point Since SDH systems will begin to appear in specific routes or overlay networks within the existing transmission network, co-existing with 140 Mb/s and 565 Mb/s systems, an issue of major importance will be the network management. This will have to cover the whole transmission network, including both the SDH and PDH parts. Point to Multi Point Point-To-MultiPoint Point-To-MultiPoint Linear Network (BUS TOPOLOGY) SDH NEs and be joined to form the Linear network as shown. The Network has LTM which marks the start of the SDH network and in between there can be add drop offices. The line protection can be given with the standby line for failure against fibre. The payload can be any of the PDH rate or the SDH line lower rate. 71
  • 72. Bus Topology RING TOPOLOGY Ring Topology Ring Topology (Contd..) 72
  • 73. Under normal operation, a 2 Mb/s tributary is sent round the ring in both the directions. The ADM assigned to drop the 2 Mb/s tributary monitors the two SDH signals for errors and delivers the one with better performance. This is known as path switching. PROJECT ON C-DOT FAMILY BRIEF HISTORY : - The Center for Development of Telematics (C-DOT) is the telecom technology development center of the government , It was established in August 1984 as an autonomous body. It was vested with full authority and total flexibility to develop state-of-the-art telecommunication technology to meet the needs of the Indian telecommunication network. The key objective was to build a center for excellence in the area of telecom technology . 73
  • 74. ACHIEVEMENTS : -  C-DOT Technology based system from 200 lines to 40,000 lines capacity in operation  More than 30,000 C-DOT Exchange totaling approximately 25 million telephone lines installed and operational in field  Deployed telecom equipment value of Rs.7500 crore  Significant technology transfer and royalty earnings  Technology development with low capital investment The C-DOT DSS FAMILY GENERAL C-DOT DSS MAX is a universal digital switch can be configured for different application as local, transit or integrated local and transit switch. High traffic or capacity of 40000 lines as local exchange or 15000 trunks as Trunk automatic exchange. The design of C-DOT DSS MAX has seen by a family concept because of it’s advantages like standardized components, commonality in hardware, field hardware that used minimum number of cards, standard cards, racks, frames, cabinets and distribution frames are used which facilitated flexible system growth that make C-DOR DSS MAX easy to maintain and highly reliable. FLEXIBLE ARCHITECTURE 74
  • 75. C-DOT DSS is a modular and flexible digital switching system which provides economical means of serving metropolitan, urban and rural environments. It include all important feature and compulsory services, required by the user with option of up gradation to add new feature and services in future. The architecture for the C-DOT DSS is such that it is possible to upgrade a working C-DOT Single Base Module. (SBM) or Multi Base Module (MBM)exchange to provide Integrated Services Digital Network (ISDN) service by adding minimum addition hardware modules while continue to having existing hardware units. Another factor of architecture Remote Switching Unit(RSU). Is support ISDN. This RSU provides switching facility locally even in case of failure of the communication path to the parent exchange.The resources, which depend upon the number of terminal, are provided within the basic growth unit the Base Module. ARCHITECTURE OF C-DOT DSS MAX C-DOT DSS MAX exchanges can be configured using four basic modules. 1. Base Module 2. Central Module 3. Administrative Module 4. Input Output Module HARDWARE ARCHITECTURE 75
  • 76. C-DOT MAX exchange can be configured using four basic modules:- 1.BASE MODULE(BM) 2.CENTRAL MODULE(CM) C 3.ADMINISTRATION STRATIVE MODULE(AM) 4.INPUT OUTPUT MODULE(IOM&IOP) (a) BASE MODULE (BM) : - The Base Module is the basic growth unit of the system . It interfaces the external world to the switch. The interfaces may be subscriber lines, Along and digital trunks. Each Base Module can interface up to 2024 terminations. The number of Base Modules directly corresponds to the exchange size. It carries out majority of call processing function and in a small exchange application, it also carries out operation and maintenance function with the help of Input-Output Module. The Basic functions of a base modules are:- 76
  • 77. 1. Analog to digital conversion of all signals on analog lines and trunks. 2. Interface to digital trunks and digital subscriber. 3. Switching the calls between terminals connected to the same Base Module. There are two types of Base Modules :- 1. Single Base Modules(SBM) 2. Multi Base Module(MBM) In SBM exchange configuration, the Base Module acts as an independent switching BM directly interface with the Input Output Module for bulk data storage, operations and maintenance function. Clock and synchronization is provided by a source within the BM. It is a very useful application for small urban and rural environments. 77
  • 78. The Base cabinet houses total 6 frames:- • Terminal Unit (TU, Top 4 Frames) system and provides connection to 1500 lines and 128 trunks. In such a configuration ,the • Base Processor Unit ( BPU,5th frame) • Time switch unit (TSU) There are following four terminals units:- 1. ANALOG TERMINAL UNIT (ATU):- The Analog Terminals Unit (ATU) is used for interfacing 128 analog termination which may be lines or trunks and providing special circuits as conference announcements and terminal tester. It consists of terminal cards, which may be a combination of Analog Subscriber Line Cards, Analog Trunk card & some Special Service Cards. (a) Analog Subscriber Ling Cards : - Two variants of subscriber line cards as LCC(Line Circuit Card) or CCM(Coin Collection Monitering) with interfaces upto 8 subscribers. Analog to digital conversion is done by per channel CODEC according to A-Law of Pulse Code Modulation so we can say that it for the subscriber connected for subscriber to exchange. A unit has 16 line cards so 16*8=128 subscribers. There are 4 unit so 4*128= 512 subscribers. 4 cards make 1 Terminal Group(TG) so TG = 4. (b) Analog Trunks Cards :- 78
  • 79. Analog trunk cards interface analog inter exchange trunks which may be of three types as TWT,EMT & EMF. These interfaces are similar to subscriber Line Cards, with only difference that the interfaces are designed to scan/drive events on the trunks as predefined signaling requirement. (c) Signaling Processor Cards : - SP Processes the signaling information received from the terminals cards. SP processes the signaling information consists of scan/drive function like original detection, answer detection, digit reception, reversal detection etc. The validated events are reported to Terminal interface controller for further processing. (d) Terminal interface controller (TIC) Cards : - TIC controls the four terminals group ( TG) of 32 channels and multiplex them to form a duplicated 128 channels, 8 mbps link towards the Time Switch. For Signaling information of 128 channels it communicates with signaling processor to receive/send the signaling event on analog terminations. It also uses to communicate with BPU. (2) DIGITAL TERMINAL UNIT( DTU ) : - Digital terminal unit is used to interface digital trunks, i.e. used between the exchanges. one set of Digital Trunks Synchronization (DTS) Card along with the Digital Trunk Controller(DTC) card is used to provide one E-1 interface of 2mbps. 79
  • 80. Each interface occupies one TG of 32 channels and four such interfaces share 4 TGs in a DTU. Here Terminal Unit Controller (TUC) is used of TIC and DSP cards. Out of 32 channels, 30 for voice communication and remaining two for Signaling and Synchronization. In DTU 4 TGs are there so total number of unit are 4*30 = 120 units in DTU. (3) # 7 or Signaling Unit Module(SUM) : - It is used to support SS7 protocol handlers and some call processing function for CCS7 calls. SS7 capability in C_DOT DSS MAX exchanges is implemented in the form of a SS& Signaling Unit Module (SUM). The sum hardware is packaged into a standard equipment frame, similar to that of terminal unit. It is a module by itself and contains global resources. It interfaces with the Time Switch via Terminal Unit Controller (TUC) on a 128 channel PCM link operating at 8mbps. ISDN To support termination of BRI/PRI interfaces and implementation of lower layers of DSSI Signalling protocol. They are used as carriers to transport bulk volume of data. With the increasing use of internet access, the use of ISDN interface is likely to go up as it provides the reliable access to the user at the rate of 64/128kbps. It is of two types i.e. circuit switched voice and data and packet switched data. In circuit 80
  • 81. switch the traffic is routed through ISDN and is packet switched data the traffic is routed through PSPDN. REMOTE SWITCH UNIT : - In this time switch card BMs are replaced by Enhanced Switch Cards(ETS). It is used when the e exchange is at a far distance from the central module. It can modified BM via 2 mbps digital links. Analog and Digital trunk interfaces are also implemented in RSU to support direct perenting of small exchanges from RSU. Instead of perenting it to the main exchange. RSU is an autonomous exchange capable of local call completion. Only the even numbered BMs can be configured as RSU i.e. a maximum 16 RSUs are possible in C-DOT DSS MAX-XL and 8 RSUs in MAX-L Maintenance and operation function are handled by the host exchange. TIME SWITCH UNIT (TSU):- Time Switch Unit (TSU) implements three basic function as time switching with in the Base Module, routing of control message within the Base Module and across Base Module and support services like DTMF circuit, answering circuit, tones etc. These functions are performed by three different functional unit, integrated as Time Switch Unit in a single frame. i.e. TIME SWITCH ( TS ) : - 81
  • 82. The Time Switch complex is implemented using three different functional cards as multiplexer/demultiplexer (TSM),Time Switch (TSS) and Time Switch Controller (TSC). The Time Switch complex performs time switching with in the Base Module : - 1. Four 128 channel multiplexed link from four different terminal units which may be any combination of ATU,DTU,#7SU AND ISTU. 2. One 128 channel multiplexes BUS from the Service Circuit interface Controller (SCIC) in the Time Switch Unit. 3. Three 128 channel link to support on board three party conference circuit (3*128). BASE PROCESSOR UNIT :- Base Processor Unit (BPU) is the master controller in the Base Module. It is impleted as a duplicated controller with memory units. These duplicated sub-units are realised in the form of the following cards :- 1. Base Processor Controller(BPC) Cards. 2. Base Memory Extendra (BME) Card. 1. Base Processor Controller(BPC) Cards : - BPC control time switching within the Base Module via the Base Message Switch and the Time Switch Controller. It communicates with the Administrative processor via Base Message Switch for operations and maintenance functions. In a SBM configuration,BPC directly interface with the Alarm Display Panel and the input Output Module. 82
  • 83. To support 8,00,000 BHCA, the BC card is replaced by High performance processor card.(HPC) i.e. Protocol Handler Card (PHC) which contain 26 slot,8slot for the power supply, 2 for memory and remaining 10 for message switching. 2. Base Memory Extender (BME) Card : - It is for the storage purpose i.e. saving memory purpose. It can store up to 16 bits CENTRAL MODULE Central module is responsible for space switching of inter-Base Module calls, communication between Base Module and Administrative Modules, clock distribution and network synchronization. The complete control conceptually is shown in following figure : - Concept Control Scheme for Space Switch 83
  • 84. The administrative processor communicates with the IOPs which act like a central storage. Administrative processor is also connected to Central Message Switches CMSA and CMSB through which AP communicates to SSC. The SSC is connected to all the CMSs (A,B,C,D) so as to communicate with all the BMs through these Central Message Switches (CMS_A,B,C,D). There are two types of Central Module : - 1.CM-XL (Extra Large) 2.CM-L(large) CM HARDWARE DISTRIBUTION :- CM Hardware is distributed in following frames : - 1. Bus Terminal Unit (BTU) Frame 2. Space Switch Unit (SSU) Frame 3. Space Switch Controller Unit (SCU) 4. Administrative Processor Unit (APU) 84
  • 85. BUS TERMINATION UNIT : - It contains Multiplexer and Demultiplexer. It is Basically an Interface Unit Between the BM and Space Switch. There are two buses- Bus 0 and Bus 1.Bus 0 contain all even time slots and Bus 1 carries all odd time slots. Bus is terminated from the Base Modulation. It controls the Space Switching between Base Modules. BTU insert the message CMS to BMS and vice versa. FUNCTION : - (a) Caters to maximum 16 BMD in release one. (b) Multiplexes the data for Space Switching. (c) Distributed 8 MHz clock and 8 KHz sync. To BMs. (e) Acts as a Gateway for CMS by message extraction/insertion scheme 85
  • 86. Types of cards used : - 1. Space Switch Mux Card(SSM) : - It multiplexes two BMs data. 2. Space Switch Mux Termination Card (SMT) :- It is used in an unequipped. SSM slot in the BTU frame to avoid any noise generated due to termination of a bus from BM in BTU frame. It offer 2A load at 5V. 3. Power Supply Card : - It supplies power to the cards and unit it work as a load sharing mode in each bus. 4. Space switch unit : Space Switch provide connectivity between two subscriber of two different BMs on time slot basis. It is responsible for switching of cards between various base modules FUNCTION : - (a) Establishes Inter Base Module Switching. (b) Caters for 16*16 Base Module switching. (c) Implements two 16*16 switching; one for bus 0 and other for bus 1. (d) Provides redundancy as copy 0,copy1(switch duplicated) Types of cards used : - 1. Space Switch Switch Cards (SSS) : - The switch card forms the part of the space switch which is situated in the Central Module. Each SSS Card caters for four base modules (16*4 switch in CM). 86
  • 87. 2. Space Switch Termination Card ( SST) : - It provides proper termination to the MUX data bus received from 16 space Switch MUX Cards. The card is used if corresponding SSS slot is unequipped. 3. Space Switch CU Bus Termination Cards (SCT) : - It is used in Space Switch Unit and Space Switch Control Unit frames of CM. It terminates CPU, address, data and control signals. 4. Power Supply Cards : - SSU employs 4 cards for supplying power and it is used in BPU,TSU,IOP. 3. Space Switching Controller Unit(SCU) : - It is a CPU complex and interfaces with space switch and clock for controlling the space switch. SSC communicates with the CMSs which in turn enable the SSC to communicate with the BMs. It contain Power Unit FUNCTION : - (a) Controller for the Switch • Time slot management and allocation • Switch monitoring for sanity • Switch diagnosis (b) Communication b/w the central message switch and Aps, BMs (c) System clock generation (d) Management of power alarms in BTU,SSU and SCU 87
  • 88. Central Message Switch (CMS) : - It consists of four different message switches and each one of them is implemented by using high speed 32 bit microprocessor. All Central Message Switches (CMS 1,2,3 & 4) are used for routing of messages across the Base Modules. Only CMS1 and CMS2 interface with the Administrative Module for routing control message between Base Processors and Administrative Processor. Type of Cards used : - 1. CPU Complex • Space Switch Controller Card (SSC) (CPU) : - This is to serve as central processing engine for the C-DOT DSS both in the BM & the CM mode. It coordinates system activities and perform call processing functions. It is used as Base Processor (BP) in the BM& as administrative processor (AP) and Space Switch Controller (SSC) in CM. • Bus interface-CPU(BIC) Card : - It is used to access memory and space switch in plane copy-0 & copy –1. • Bus interface Device (BID) Card : - It along with bus interface CPU (BIC) card provides the cross connection b/w duplicate CPU’s (controller) an duplicate device (memory) in such a way that any one failure either at CPU or at device does not bring down the whole processor complex. 88
  • 89. • Memory Card (2MB) : -It provides storage space and interfaces to a standard 6800 CPU bus. Both word & byte accessory are possible on the memory space. 2. Switch Interface • BIC Card • Bid Card • Space Switch Controller Termination (SCT) 3. System Clock and PSU errors • Space Switch Clock Card(SCK) : - It is the source of clock signal to the space switch switch cards & the space switch mux cards which constitute the space switch. It is used for the control of timing and for synchronizing of the space switches. Administrative Processor Unit (APU) : - • Status of all module of the exchange is maintained by the AP and whenever a problem is reported required action is initiated to clear the problem. All the global resource like trunks. Time slots etc are managed by the A.P. Directory to equipment number translation for the establishment of a call is performed by AP All global data is managed by the AP. In a multimodule exchange all the call processing. Administration and maintenance function are supervised by the AP. 89
  • 90. Function of APU : - 1. All administrative function in the system 2. Interaction with SSC through central message switches CMS(A,B) (SSC/BM to IOP via AP). 3. Communication to ADP. 4. Administrative Processor (AP) somewhat similar to BP. 5. Maintain status of all modules of the exchange. 6. Initiate whenever a problem is reported required action to clear the problem. 7. Switch over of copies, diagnostic of faulty units and put in service units which are out of service etc, are initiated and supervised by the AP. 8. Manage all the global resource (like trunks,ts etc.) 9. Perform directory to equipment no. translation for the established of a call. 10. Connects of exchange to the operator through IOP. 11. Handle the man-machine communication. 12. During initialization of the multimode exchange AP gather initialization request from different BMs, collects code and data from IOP and send it to corresponding BM’s. Types of Card used : - 90
  • 91. 1. CPU Complex (APU) • CPU Card • BIC Card • BID Card • Memory Card(2MB) 2. Central Message Switch-CMS (A,B,C,D) 1. Message Switch Controller Card (MSC) 2. Message Switch Device Card (MSD) CALL PROCESSING GENERAL CONCEPT There are five function steps of call processing including the location of the originating and terminating equipment. These steps are : - • Origination : - Origination begins when the subscriber line goes off hookor incoming trunks seized. It receives the incoming digits, selects the digit analysis tables, and determines the screening information for this call. • Digit Analysis: - It interprets the digits it receives from origination ,select a destination for each call, and passes the dialed digits to routing. • Routing/Screening:- Routing uses the destination information from digit analysis and screening information origination to select the terminating trunk group or line. 91
  • 92. • Charging : - It uses the charging information from routing to expand the charging data into a formate usable by call accounting process. • Termination : - The last step in call processing is termination. Termination Processor is different for calls destined for lines and call destined for trunks. Trunk termination : - A trunk member of the trunks group is selected based on a predetermined pattern. After selection the digits are out pulsed to the distant office. Line termination : - The line identified in routing is checked to determine the line has any special features. Ringing is applied to the line if applicable or the special feature is activated. SIGNALING What is Signaling ? Signaling refers to the exchange of information between call components required to provide and maintain service. As users of the pubic Switched telephone network, we exchange signaling with network element all the time. Examples of signaling between a telephone user and the telephone network include. Dialing digits, providing dial tone, accessing a voice mailbox, sending a call waiting tone, dialing *66(to retry a busy number), etc. 92
  • 93. Signaling system 7 is means by which element of the telephone network exchange information. Information is conveyed in the form of messages. Signaling System 7 messages can convey information such as : SS7 is characterized by high-speed packet data, and out-of-band signaling. ISDN (INTEGRATED DIGITAL SERVICE NETWORK TERMINAL UNIT) One of the four ATUs/DTUs in a Base module be replaced by ISTU to provide Basic Rate Interface (BRI)/Primary Rate Interface in C-DOT DSS. It is directly connected to TSU on 8 Mbps PCM Link. INTRODUCTION ISDN is comprised of digital telegraphy and data transport services offered by region telephone carries ISDN involves the digitization of the telephone network which permits voice, data, text, graphics ,music ,video and other source material to be transmitted over exiting telephone wires. The emergence of ISDN represent an efforts to standardize subscriber service user/network interface and network and inter network capabilities. ISDN application includes high speed image application , addition telephone lines in home to serve the telecommuting industry, high 93
  • 94. speed file transfer and video conferencing. Voice service is also an application for ISDN. Architecture of ISDN Terminal Unit In C-DOT DSS architecture the ISDN interface are terminated on a new add on terminal unit as ISTU. A maximum of 256 bearer channels are provided by integrating one ISTU which can be configured to support any combination of BRI or PRI interfaces. If the requirement of PRI/BRI interfaces more than 256 bearer channels ,one or more. ISTU, can be integrated in C-DOT DSS with the option of equipment them in the same BM of distributed across different BMs in the exchange. The architecture also support in signaling providing time slots for switching channels, carrying data & voice. SERVICE There are two types of services associated with ISDN:- 1. BRI 2. PRI 1. ISDN BRI Service The ISDN Basic rate interface(BRI) Service offers Two B channels and one D channels (2b+D). BRI B channels service operated at 64 Kbps and is carry user data. BRI d channels service operates at 16 Kbps and is meant to carry control and signaling information, although it support user data 94
  • 95. transmission under certain circumstances. The BRP also provides for framing control and other overhead, bringing its total bit rate to 192 Kbps. The BRI physical layer specification is International Telecommunication Standard Section (ITU-T). (Formerly the consultative committee for international telegraph and telephone (CCITT) 2. ISDN PRI SERVICE The ISDN traffic is of two distinct types:- • Circuit switched voice & data • Primary Rate Line (PRL) Basic Rate Line (BRL) Card The BRL is an interface to the switching system supporting 8 U- interface towards the user. It interfaces with the ISDN Terminal Controller(ITC)/Switching Network for signaling and switching of voice and packet information. The function of the BRL card include HYBRID for 2 to 4 conversion and echo cancellation monitoring of lines status, it’s activation and deactivation, over voltage protection (for protect the exchange and the BRL card from high voltages),test access. Primary Rate Interface Line Card(PRL) 95
  • 96. The PRL Card is an interface to terminate a 2.048 Mbps link ,using symmetric twisted pair cables with characteristic impedance of 120 ohms. Each PRL card form a terminal group (TG) and a maximum of 8 PRL, cards can be accommodation in each ISTU. ISDN USER PART( ISUP ) The ISDN User Part(ISUP) defines the protocol and Procedures used to set-up. Manage, and release trunk circuit that carry voice and data calls over the public switched telephone network(PSTN). ISUP is used for both ISDN and non-ISDN calls. Calls that originate and terminate at the same switch do not use ISUP signaling. ALARM DISPLAY PANEL (ADP) The ADP is used in the C-DOT to display the status of the system in single base module configuration . It can also be used with a two base module system . The status is displayed on light emitting diodes (LEDs)and seven segment LED display. Fresh faults are reported on the panel by blinking the LEDs accompanied by an audio alarm to draw the attention of the operator in turn is expected to acknowledge the faults . ADP is a microprocessor based hardware unit which is attached to the BP (in SBM) or AP(IN MBM) by HDLC(HIGH DATA LINK CONTROLLER) link for providing audio visual indication of system faults . a seven segment display shows the count of lines and trunks currently faulty. 96
  • 97. FUNCTIONAL DESCRIPTION :- The ADP is housed on three cards :- 1. Controller card . 2. display card . 3. power supply card . 1. Controller card :- It is a subdivided into following blocks:- (a) CPU LOGIC :- It generates clock required by microprocessor, buffers for buffering for CPU address and data bus , power on reset logic to generate the signal. (b) MEMORY :- Occupies address space RAM. (C) DISPLAY CARD INTERFACE :- Consist of logic which generates the various strobes for the registers on the display card (D) INTERRUPT AND WATCHDOG DOG :- The sources of interrupt for the CPU are :- (i) Real time timer 97
  • 98. (ii) Acknowledge switch (iii) LED test switch (iv) The two HDLCs. The sources for generate one interrupt line for the microprocessor. (e) INPUT /OUTPUT PORTS AND AUDIO ALARM :- input port is used to determine the configuration of the system and the source of the interrupt. Output port is used for cleaning the various interrupts & for enabling the audio alarm. The audio alarm is implemented using a piezo-electric buzzer (f) COMMUNICATION INTERFACE:- Consists of clock generator for the HDLs. . SYSTEM CAPACITY INTRODUCTION The capacity of C-DOT DSS is defined in terms of the following parameters: • The termination capacity express as the number of lines and trunks • The amount of traffic (in erlangs) that can be switched • The number of Busy Hour Call Attempts (BHCA) that can be processed with a given call-mix while meeting the overall service quality requirements. 98
  • 99. This section indicates the maximum capacity of different system element as well as that of complete exchange, equipped to its ultimate termination capacity. It has been ensured that the specified parameters are valid to meet overall reliability objectives for the C-DOT DSS as specified in ITU-T recommendation. TERMINATION CAPACITY A terminal Card is the basic system element. It interfaces/terminates the lines and trunks. The next higher element is a Terminal Unit. The types of terminal card and terminal unit used in C- DOT DSS along with its function are already explained in chapter ‘3’ &’4’. Termination capacity of BM is 488 analog lines and that of LM in 768 analog lines. A BM can be concentrated with 2 LM’s to provide maximum termination capacity of 2024 Analog lines. Incase of BM, a maximum of 256 B channels are provided at the cost of 512 analog lines. One to one replacement of Base channel is planned in immediate future. Base Module and Line Module are the highest level of system elements. Each Base Module has four Terminal Units whereas a Line Module has six Terminal Units. A maximum of 16 BMs can be connected in MAX-L and 32 BMS can be connected in MAX-SL configurations. EXCHANGE CONFIGURATION C-DOT DSS MAX can be configured to support any combination of lines and trunks, for different application in the network as local 99
  • 100. Exchange, Local cum Tandem Exchange. Trunks Automatic Exchange(TAX) or Integrated Local cum Transit (ILT) Exchange. In this maximum configuration, upto 40,000 lines and 5,500 trunks are supported when configured as Local/Local cum Tandem. When configured as TAX. 14,500 trunks are supported. Termination Capacity of Exchange Configuration Note : Out of the total equipment capacity, a maximum of 30,000 Lines may be Remote Subscriber through RSUs in MAX-XL whereas 14000 lines. SOFTWARE ORGANIZATION The software is written in high level language ‘C’ & distributed over various processors and is structured as a hierarchy of virtual machines. The software features are implemented by communication processes. The operating system provides communication facilities such that the processes are transparent to heir physical locations. Resource are identified as ‘global’ or ‘local’ depending upon their distribution in the system. The resource which depends upon the number of terminal are provided within the basic growth module. E.g., Processor architecture is characterized by distributed control & message based communication in order to achieve a loosely-coupled network for a flexible system architecture. ROLE OF SOFTWARE IN C-DOT DSS 100
  • 101. INTRODUCTION The main feature of the software architecture of DSS-MAX are as: 1. Distributed architecture to ma the distributed control architecture 2. Layered architecture with loosely coupled modules & well defined message interfaces. 3. Use of high level language 4. Modular design with each layer providing higher of abstraction 5. Time critical processes in assembly language These feature help in to achieve the following objectives: 1. Simplicity in design 2. Increased reliability due to fault tolerant software 3. Flexibility with option of up gradation to add feature & service 4. Efficiency and strict time check 5. Ease of Maintainability C-DOT DSS MAX Layered Software Architecture SOFTWARE SUBSYSTEMS The main subsystem of C-DOT DSS MAX are as : 1. C-DOT real Time operating system 2. Peripheral Processors subsystem 101
  • 102. 3. Maintenance subsystem 4. Database subsystem 5. Administration subsystem 6. IOP subsystem 7. Call Processing subsystem These subsystem are responsible for providing the following basic services: 1. CDOS : It is the operating system & provides the following function : 1. Process management 2. Resource management 3. Interrupt handling 4. Online & offline debugging 2. Peripheral Processor subsystem : It controls all the telephony software. It also carries out the commands given by the Base Processor for generating suitable telephony events. Another function is to carry out all the maintenance related test function on hardware. It consists of 8-bit microprocessors programmed in assembly language 3. Call processing subsystem: 102
  • 103. It receives the information about telephony event that occur outside the exchange. It processing this incoming information & gives commands to the peripheral processors for interconnecting subscriber through the switching network. A special feature is to generate Exhaustive Call Event Record for every call. 4. Maintenance subsystem: It provides the following function: • Initialization • System integrity • Switch maintenance • Terminal interface • Human interface 5. Administration subsystem: It consist of traffic, billing exchange performance measurement & human interface functions. It also provides online software patching capability. It is responsible for maintaining a large number of traffic records on the basis of information received by it through Call Event Records. Over 200 man-machine commands are provided for these operations. 6. Database Subsystem: It provides for the management of global data. The main objectives are: 103
  • 104. (a) Easy access (b) Quick access (c) Transparency (d) Consistency (e) Security (f) Synchronization BASIC SERVICE IN DSS MAX The most important function of a DSS switch is to process subscriber calls. Subscribers’ call can be classified as line-to-line, line-to- trunk, and trunk-to-trunk. A lint-to-line is a call that starts on a line served by a DSS switch and terminates to another line served by the same switch. The BMs involved in the call will perform almost 95% of the total call processing function. During a line-to-line call, the origination BM detects when a subscriber’s telephone receiver as been picked up. The BM provides the dial Tone and then removes the Dail Tone when first digit is dialed. It then collects and analyzes the dialed digits. Next, the BM sends a request to the AM for a call path. The terminating BM locates the subscriber line for the line-to-line call and provides ringing. When AM has selected an available path. It alerts the CM to set up link between the BM’s. The CM provides call paths between BM’s and carries all internal system communications. 104
  • 105. The function of BM, AM, and CM in trunk-to-trunk call are basically the same as line-to-line call described above except that the originating BM detect a trunk seizure rather than a subscriber picking up the receiver. Also, the terminating BM locates as available trunk instead of line. The above scenarios may differ slightly, if the call involves both and trunk. Lint-to-Line call can be of two types: • INTRA_BM: When both subscriber lines connected to same BM. This doesn’t require use of CM. • INTER_BM: When both subscriber lines are to different BMs. This requires use of the CM. OTHER SERVICE PROVIDED BY MAX The MAX provides the following features apart from processing of a telephone call: Number identification Service: 1. Calling Line Identification Presentation (CLIP): The Calling Party’s details are given to the user along with the incoming calls. 2. Calling Line Identification Restriction(CLIR): With this service the calling party may restrict presentation of it’s number to the called party. 105
  • 106. 3. Calling Line Identification Restriction Override (CLIRO): The subscriber with this facility receives the details of the calling party even if it has asked for it’s restriction. 4. Malicious Call Identification (MCID): During conversation the subscriber can use a procedure to identify the malicious caller. Call offering supplementary Service: • Call Forwarding ?Unconditional(CFU)L It allows the user to forward all incoming calls to another number. • Call Forwarding Busy(CFB): It allows the user to forward all incoming calls to another number if the user’s number is not free. • Call Forwarding No Reply (CFNR): It allows user to forward all incoming calls to another number if the user doesn’t respond in a fixed number of rings. Call completion Services: 1. Call Waiting: A Subscriber engaged in a call, is given an indication that another caller is trying to call him up. The user can then talk to a caller by keeping the other holding. 2. Call Hold: This allows the user to put th call into wait for the being and initiate or accept a new call. The user can retrieve the call put on hold whenever required. Multi Party Services: 106
  • 107. 1. Three Party Conference: It enables the user to establish, participate in and control a simultaneous communication involving the user and two other parties. The served user can disconnect one party, disconnect the three-way conference or communicate privately with one of the parties. 2. Multi Party Conference: It allows uses to establish and control a conference involving at the most 6 users. The conference controller may add, drop, isolate, and reattach parties from the conferences. Misc. Service: 1. Hot Line(Timed): It allows the subscriber to establish calls to a pre- registered number. After getting the dial tone, if the subscriber doesn’t dial any number for a minimum amount of time, then he is connected to the pre-registered number. If the subscriber dials a number, then normal connection is established. 2. Hot line(Without Time-Out): As soon as the subscriber lift the handset, the call to the pre –registered number is established. Normal outgoing calls can’t be made. POWER PLANT OF C-DOT DSS MAX From the power supply bus bar power is tapped through cables to each suite separately. In this there is five modules, each having 200amp. As input. In this, AC is input and DC is output. In this input is between 340- 475 V and output is 48V. There are two batteries if one is not conduct than other is used. These are connected together if both are 107
  • 108. disconnected than till 15-20 minutes power is supplied. From the rectifier, which derives 48V DC from 440V AC. Power cables are terminated on the DC distribution panel (DCDP). From the DCDP, power cables run along the cable runways and ladders and terminated on the power distribution panel(PDP). Distribution panel consists of two bus bars for –48V, one each for copy 0 and copy 1 equipment. Similarly there are two bus bars for ground. For each base module cabinet, the power i.e.-48V is tapped twice one for each plane through a fuse. Whenever the fuse blows off the LED, which is connected in parallel glows on the FBI card, and an audio alarm is given at a centrally located point. 108
  • 109. REFERENCES 1. Wikipedia, the free encyclopedia 2. Winsen .com 3. www.bsnl.co.in 4. www.seachq.co.in 5. ITI LIMITED Books 109