0

Wireless communication and its standards

3,164

Published on

This ppt is very useful to know about the wireless communication and its standards......

Published in: Education, Business, Technology
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
3,164
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
114
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

Transcript of "Wireless communication and its standards"

  1. 1. AGENDA WIRELESS COMMUNICATION. CELLULAR TECHNOLOGY. STANDARDS EVOLUTION OF MOBILE TECHNOLOGY. MODULATION&MULTIPLEXING. FDMA/CDMA/TDMA. GSM/CDMA. GSM ARCHITECTURE(MS/BSS/NSS FUNCTION). GSM CHANNEL.
  2. 2. WIRELESS COMMUNICATION Definition: Transfer of information without ‘wires’. Information can be transmitted between two location using a signal that can be either analog or digital in nature. In telecommunication networks: Digital transmission is exclusively used. Wireless communication can take several forms: Microwave (Point-Point)-Low and medium capacity over short and medium distance. Microwave radio transmissions have been used in telecommunication industry for the transport of point-point data where information transmissions occur through carrier signal. Satellite communication- Low and medium capacity over long distance. Wireless Technology: To understand WT, a basic understanding of the radio frequency(RF) spectrum is required. It`s rate of oscillation in the range of about 3KHZ-300GHZ.
  3. 3. CELLULAR TECHNOLOGY Cellular network is a radio-based technology; radio waves are electromagnetic waves that antenna propagate. Most signals are in the 850MHZ, 900MHZ, 1800MHZ, 1900MHZ frequency bands. Mobile radio Transmission system may be classified into: Simplex, Half-Duplex, Full-Duplex. Simplex: One way communication- Paging System. Half-Duplex: Two way communication, but same channel for TX and RX. Push-To-Talk, release-to-listen. Ex: walkie talkies- Applies to TDD system. Full-Duplex: Two way communication in different frequency, simultaneously transmit and receive. Ex: Mobile phone. Applies to FDD system. TDD- Time Division Duplex FDD: Frequency Division Duplex One channel for uplink and down link Separate channel for uplink and downlink ADV: Effective spectrum usage ADV: Suitable for voice communication DIA ADV: Time delay DIS ADV: Spectrum usage is high.
  4. 4. MICROWAVE COMMUNICATION Microwave communication requires line of sight and earth towers to transmit information and hence have relatively smaller area coverage. One tower receives a signal it amplifies it and sends it to the next tower. The microwave systems have the capability to carry large amount of data both digital and analogue at high speed and are mostly used for the transmission of telephone and television signals. Advantages: No cables needed. Multiple channels available. Wide bandwidth. Disadvantages: Line-of-sight will be disrupted if any obstacle, such as new buildings, are in the way Signal absorption by the atmosphere. Microwaves suffer from attenuation due to atmospheric conditions. Towers are expensive to build. MW equipment providers: Ericsson Nokia Alcatel Intracom
  5. 5. Evolution of Cellular technology
  6. 6. RANGE DATA RATE OF IEEE/ITU-T STANDARD
  7. 7. STANDARDS What is STANDARD: Standard is a level of quality, especially one that people think is acceptable. standard is nothing but collection of defined criteria's to asses product ,service or system. Why do we need standards? Standards can be found throughout our daily lives but why do we need them? Products might not work as expected. They may be of inferior quality and incompatible with other equipment, in fact they may not even connect with them. non-standardized products may even be dangerous. Standardized products and services are valuable User 'confidence builders', being perceived as: Safe. Secure. high quality. Flexible. As a result, standardized goods and services are widely accepted, commonly trusted and highly valued.
  8. 8. WIRELESS COMMUNICATION STANDARD ITU-International Telecommunication Union. IEEE- Institute of Electrical and Electronics Engineers. The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations, known as the Organizational Partners. 3GPP is the standard body behind the (UMTS) that is the 3G upgrade to GSM networks. The 3rd Generation Partnership Project 2(3GPP) is a collaboration between telecommunications associations to make a globally applicable 3G mobile phone system specification within the scope of the ITU's IMT-2000 project. 3GPP2 is the standard body behind the competing 3G standard CDMA2000 that is the 3G upgrade to CDMAONE networks used mostly in the United States. GSM/GPRS/EDGE/W-CDMA is the most widespread wireless standard in the world. A few countries (such as China, the United States, India, South Korea and Japan) use both sets of standards, but most countries use only the GSM family.
  9. 9. STANDARDS What is ITU: International Telecommunication Union. is an agency of the United Nations (UN) whose purpose is to coordinate telecommunication operations and services throughout the world. The ITU sets and publishes regulations and standards relevant to electronic communication and broadcasting technologies of all kinds including radio, television, satellite, telephone and the Internet . It has three sectors: 1.ITU-T Telecommunication Standardization sector It coordinates standards for telecommunications. Ex: GSM, 3G, 4G. 2.ITU-R Telecommunication Radio communication sector. It coordinates standards for radio communications services as well as the international management of the radio frequency spectrum and satellite orbits. Ex: ULTRA-HDTV & 3D-TV 3.ITU-D Telecommunication Development sector. Assists countries in developing and maintaining internal communication operations
  10. 10. WIRELESS COMMUNICATION STANDARD STAND LIST OF TECH BW MODULATION FREQ BAND ITU-T GSM-2G 200KHZ GMSK 900/1800MHZ ITU-T GPRS-2.5G 200KHZ GMSK 900/1800MHZ ITU-T EDGE-2.75G 200KHZ GMSK/8PSK 900/1800MHZ ITU-T W-CDMA-3G 5MHZ QAM/64QPSK 2100MHZ ITU-T LTE-4G 5-20MHZ QAM/QPSK 2300MHZ QUALCOMM CDMA-2000 1.25MHZ QPSK 850MHZ IEEE BLUETOOTH 800Kbps-Data rate GFSK 2.4GHZ IEEE WIFI 11Mbps-Data rate GFSK 2.4GHZ IEEE WIMAX 30Mbps-Data rate OFDM 5.8GHZ
  11. 11. Evolution of Cellular technology Generations Definitions/Data rate Features 1G-1980-1990 Analog-14.4Kb/s Voice 2G-1990-2004 Digital narrow band CKT Voice, SMS, Conference calls, Caller ID. 2.5G-GPRS Digital narrow band CKT/Packet data Voice+Data/WAP/MMS Voice Data/WAP/MMS/Web browsing/Short audio video clips. 2.75G-EDGE Digital narrow band CKT/Packet data 3G-2004-13 Digital broadband packet data/Data rate200kb/s-2mb/s High speed web/Video conferencing/Navigation/maps 3.5G-HSDPA Digital broadband packet data/Data rate8Mkb/s-10Mb/s High speed web/Video conferencing/Navigation/maps Multiplayer gaming 3.75G-HSUPA 4G-LTE Digital broadband packet data/Data rate1.4Mb/s-5Mb/s Digital broadband packet data very high throughput/Data rate-100Mb/s-1Gb/s High speed web/Video conferencing/Navigation/maps High quality streaming video/High quality video conferencing.
  12. 12. Evolution of Cellular technology Generations Advantages 1G-1980-1990 Focus on voice 2G-1990-2004 Possibility of wireless data service. More flexible. 3G-2004-13 Rich multimedia services. More bandwidth and security. High data rate. 4G-LTE(Up coming) Broadband access in remote locations. Higher BW tight network security. Disadvantages Data service non-existent Impossible international roaming. Poor handoff reliability. Large Phone size. Unable to handle complex data such as video. Circuit switch network, does not support high data rate results weaker digital signal. Expensive service license. Infrastructure for 3G. Very expensive.
  13. 13. MODULATION TECHNIQUE Modulation: Modulation is the process of superimposing a low frequency signal on high frequency carrier signal. It`s process of mixing a signal with sinusoid to produce a new signal. Will have certain benefits of an un-modulated signal especially during transmission. Modulation is a form of change process where we change the input information into a suitable format for the transmission medium. It`s general technique of shaping a signal to convey a information. Keying : Keying is a family of modulation forms. The goal of keying is to transmit digital signal over an analogue channel. Analog Modulation: AM, FM, PM, QAM, SM, SSB. Digital Modulation: ASK, APSK, CPM, FSK, MFSK, MSK, PSK. Spread spectrum: CSS, DSSS, FHSS.
  14. 14. DIFF-AM FM PM AM FM Amplitude of the carrier signal increase or decrease Frequency of the carrier signal increase or decrease Phase of the carrier signal increase or decrease Can Transmit long distance Short Distance FM and PM are inseparably links BW is small BW is high Phase is integral of frequency Poor sound quality Better than AM PM used for digital form of txn Range 535-1705Khz upto 1200 Bps 88-108 Mhz upto 1200-2400Bps ASK+PSK=QAM Impacted with environmental noise Doesn`t degrade linearly with distance While Phase changes Frequency will change and vice-versa Impacted with physical barrier PM
  15. 15. AM FM PM
  16. 16. MULTIPLEXING TECHNIQUE Multiplexing: Combining multiple stream information for transmission over a shared medium. Several input one output. To combine many signals(voice or data) so they can sent over one transmission medium. De multiplexing: Reverse function of multiplexing. One input several Output. Guard Band: It`s an unused part of the radio spectrum between radio bands. FDM TDM WDM Can be used with analog signal. Can be used with digital signal or analog signal carrying digital data. Multiplexes no.of optical carrier signal onto a single optical fiber by using different wavelength. No.of signal carried signal on same medium. Data from various sources are carried in respective frames. Its applied to CWDM&DWDM By allocating to each signal a different frequency band. Each frames consists of time slots. Each wavelength can carry different signal. SDH 2.5G, 10G, ATM, IP Guard bands are used for avoid interference, Each source assigned time slot per frame. Provide much better latency. Sync pulses added to identify the beginning of each frame. Provide much better flexibility. Best application: Long Haul.
  17. 17. Frequency Division Multiple Access Frequency is a precious and natural resource. Each mobile is assigned a separate frequency channel for the duration of the call. MS will have one downlink frequency band and one uplink frequency band. Guar band is required to prevent adjacent channel interference.
  18. 18. Time Division Multiple Access TDMA is a type of multiplexing where two or more channel of information are transmitted over the same link by allocating a different time interval for the transmission of each channel. TDMA separates users according to time, it ensures that there will be no interference from simultaneous transmission. Each user is given a specific slot. It`s the only technology that the user has occupied predefined time slots. Only one mobile terminal transmits during each slot.
  19. 19. Code Division Multiple Access CDMA is a digital wireless air interface and networking standards based on the principle of spread spectrum technology, which allow multiple users to access the system simultaneously on the same carrier frequency. Bandwidth occupied by the signal is much larger than the information transmission rate. Each symbol of bit is transmitted as a larger number of bits using the user specific code – Spreading. Use of orthogonal codes to separate different transmissions. But all users use the same frequency band together.
  20. 20. FDMA CDMA TDMA Differ signals are assigned frequency channel. A channel is a frequency. Users can access the system simultaneously on the same carrier frequency by using SS. Users can access the same frequency spectrum by dividing the time slots. Each channel can be assigned to only one user at a time. By using unique assigned codes users can be occupy the frequency. 2 or more channel of information are transmitted over same link by allocating diff time interval. SS: The signal occupies a BW in excess of the minimum necessary to send the information. FHSS: improves C/I ratio by utilizing many freq channel. And also fading and mmultipath prob. ADV: Make before break connection.” soft hand off” Very high spectral capacity. ADV: “Hard hand off”. Easily adapt data & voice transmission. Users separates by dividing time slots. It ensures no interference. DIS ADV: Channel pollution. There is no international roaming. DIS ADV: “call drop” may occur when moving one to another. EX: CDMA 2000-1X RTT, CDMA 2000-1X EVDO EX: GSM EX: AMPS, TACS
  21. 21. What is GSM GSM stands for Global System for Mobile communication. The European system was called GSM and deployed in early 1990`s. Designed on 900MHZ and 1800MHZ range. It was the first fully digital system utilizing the 900MHZ frequency band. The initial GSM had 200KHZ radio channel s, 8-full rate or 16-half rate TDAM channels per carrier. The GSM makes use of narrowband Time Division Multiple Access (TDMA) technique for transmitting signals. The GSM was developed using digital technology. It has an ability to carry 64 kbps to 120 Mbps of data rates. Presently GSM support more than one billion mobile subscribers in more than 210 countries throughout of the world. The GSM provides basic to advanced voice and data services including Roaming service.
  22. 22. What is CDMA IS-95-Code Division Multiple Access. 824-849MHZ. Each carrier 1.24MHZ. 4 types of logical channel: A pilot, A synchronization, 7 paging, 55 traffic. Channels are separated using different spreading codes. QPSK modulation scheme. 64 orthogonal walsh code are used. It`s used to differentiate between the transmission with in the cell. Using PN offset we can separate the cells
  23. 23. DIFFERENCE B/W GSM & CDMA GSM CDMA TDMA CDMA FHSS DSSS 900/1800MHZ CHANNEL SPACING(BW)-200KHZ FREQUENCY REUSE MODULATION-GMSK USERS SEP BY DIFF TIME SLOTS FREQ MUST BE PLANNED 11 TYPES OF LOGICAL CHANNEL NEED MORE NO.OF BTS TO COVER LA DEPENDING ON.TRAFFIC-N/W CAP,COV INCREASE 850MHZ CHANNEL SPACING(BW)-1.25MHZ PN REUSE MODULATION-QPSK USERS CAN ACCESS WHOLE SPECTRUM NO FREQ PLANNING 4 TYPES OF LOGICAL CHANNEL NEED LESS NO.OF BTS TO COVER LA DEPENDING ON NOISE-N/W PLANNED
  24. 24. DIFFERENCE B/W 900/1800 MHZ FREQ BAND 900MHZ 1800MHZ PROVIDE LARGE COVERAGE PROVIDE SMALLER COVERAGE IT`S MAINLY SUPPORTED FOR SUBURBAN, RURAL IT`S MAINLY SUPPORTED FOR URBAN, DENSE URBAN AREA LESS NO.OF BTS WE CAN PROVIDE MORE COVERAGE. WE USE MORE NO.OF.BTS. CAPACITY WISE WE CAN USE MORE BTS WITH IN A CERTAIN RANGE. VICE-VERSA
  25. 25. Comparison b/w 900/1800MHZ Parameters 900 1800 Multiple Access TDMA/FDMA/FDD TDMA/FDMA/FDD Uplink 890-915MHZ 1710-1785MHZ Downlink 935-960MHZ 1805-1880MHZ No. of. Channels 124 374 Channel spacing/BW 200KHZ 200KHZ Channels/Carrier 8 time slot 8 time slot 0.577ms 0.577ms Frame duration 4.62ms 4.62ms Duplex spacing 45MHZ 45MHZ Time slot duration
  26. 26. Why GSM? The ETSI group aimed to provide the following through the GSM: Improved spectrum efficiency. International roaming. Low-cost mobile sets and base stations (BSs). High-quality speech. Compatibility with Integrated Services Digital Network (ISDN) and other telephone company services. Support for new services.
  27. 27. GSM ARCHITECTURE The GSM network can be divided into following broad parts: The Mobile station(MS). The Base Station Subsystem(BSS). The Net work Switching Subsystem(NSS).
  28. 28. GSM network areas Cell: Cell is the basic service area: one BTS covers one cell. Each cell is given a Cell Global Identity (CGI), a number that uniquely identifies the cell. Location Area: A group of cells form a Location Area. This is the area that is paged when a subscriber gets an incoming call. Each Location Area is assigned a Location Area Identity (LAI). Each Location Area is served by one or more BSCs. MSC/VLR Service Area: The area covered by one MSC is called the MSC/VLR service area. PLMN: The area covered by one network operator is called PLMN. A PLMN can contain one or more MSCs.
  29. 29. The Mobile Stations(MS) MS is the user’s handset and has two parts. ME+SIM. Mobile Equipment: •Radio equipment •User interface •Processing capability and memory required for various tasks. It provides the air interface to the user in GSM networks.
  30. 30. The Mobile Station(MS) Functions of mobile stations: Voice and data transmission and receipt. Frequency and time synchronization. Monitoring of power and signal quality of surrounding cells. Provision of location update even during inactive state. An MS can have any of the following state: IDLE: The MS is ON but a call is not in progress. ACTIVE: The MS is ON and a call is in progress. DETACHED: The MS is OFF.
  31. 31. Network Identities MSISDN: Mobile Station ISDN is registered in the telephone directory and used by the calling party for dialing. Shall not exceed 15 digits. IMSI: International Mobile Subscriber Identity, The IMSI is an unique which is used internationally and used within the network to identify the mobile subscribers. Max 15 digits. TMSI: Temporary Mobile Subscriber Identity. It`s temporary IMSI no. The VLR assigns a TMSI to each mobile subscribers entering the VLR area. Assigned only after successful authentication. TMSI changes on location updation. TMSI is less than 8 digit. MSRN: Mobile Station Roaming Number. It`s temporary identity which is assigned during the establishment of a call to a roaming subs. IMEI: International Mobile Equipment Identity. It`s an unique code allocated to each mobile equipment.
  32. 32. Functions of BSS The BSS composed of TWO parts: The Base Transceiver Station(BTS) The Base Station Controller(BSC). The interface between BSC and BTS is designed as an A-bis interface. The interface between the MSC and the BSS is a standardized SS7 interface (A-interface). The BSS is responsible for all the radio related functions in the system, such as:  Radio communication with the mobile units Handover of calls in progress between cells  Management of all radio network resources and cell configuration data.
  33. 33. Functions of BSC It`s part of BSS system BSC manages the radio resources for one or more BTSs. It handles radio channel setup, frequency hopping and handovers. The function of the BSC is to allocate the necessary time slots between the BTS and MSC. Control of frequency hopping. The BSC is connected to the MSC on one side and to the BTS on the other. Handling of MS connections and performs the intercell handover for MSs moving between BTS in its control. Manage the Handover within BSS area. Knows which mobile stations are within the cell and informs the MSC/VLR about this. Controls several transmitters.
  34. 34. Function of Base Transceiver Station BTS acts as the interface between MS’s (Mobile Station) and the network, by providing radio coverage functions from their antennae. It`s located between the Mobile Station (MS) and the Base Station Controller (BSC). The BTS is basically classified into two types: Indoor & Outdoor. The primary responsibility of the BTS (Base Transceiver Station) is to transmit and receive radio signals from a mobile unit over an air interface. A BTS is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between 1 and 16 transceivers, depending on the density of users in the cell. Encoding, encrypting, multiplexing, modulating, and feeding the RF signals to the antenna. Decoding, decrypting, and equalizing received signals
  35. 35. Cont…. Transcoding and rate adaptation. Voice through full- or half-rate services Trans-coding to bring 13-kbps speech to a standard data rate of 16 kbps and then combining four of these signals to 64 kbps is essentially a part of BTS, though, it can be done at BSC or at MSC. Every BTS or RBS has standardized hardware units. EX:ERICSSON RBS 2000 FAMILY: (INDOOR UNIT)/GSM 900/1800 FREQ BAND: DXU: Distribution Switching Unit. TRU: Transceiver Unit. CDU: Combined Distribution Unit. CXU: Configuration Switching Unit. Or Rx Splitter. PSU: Power Supply Unit.
  36. 36. Cont… DXU: It`s CPU of BTS acts as an interface b/w transmission networks and transceivers. Manages the link resources and connects the traffic time slots from the BSC link to the TRU’s. DXU can work on both 1.544MBPS(T1), 2.048MBPS(E1). TRU: It is responsible for radio transmitting, radio receiving, power amplification and signal processing. EdTRU, EDRU, RRU-Support for EDGE, GPRS. CDU: It`s interface b/w transceivers and antenna system. The task of the CDU is to combine signals to be transmitted from various transceivers and to distribute received signals to the receivers. A range of CDU types have been developed to support different configurations within the RBS 2000 family. EX: CDU-G, CDU-F. CXU: Positioned b/w CDU & TRU. It distributed b/w Rx signals from CDU to TRU within the same BTS. 1 CXU can support max 3CDU. PSU: The PSU rectifies the power supply voltage to the +24 VDC necessary for RBS operation.
  37. 37. Functions of Network Switching Subsystem NSS or GSM core network is the component of GSM system that carries out call switching and mobility management functions for mobile phones. It was originally consisted of circuit switched core network used for traditional GSM sevices such as voice call, SMS circuit switch data calls. Now extended with an packet switched data services known as GPRS core network. Main functions of NSS: Call control, charging, mobility management, subscriber data handling. The switching system includes the following functional elements. MSC-Mobile Switching Centre. HLR-Home Location Register. VLR-Visitor Location Register AUC-Authentication Centre EIR-Equipment Identity Register.
  38. 38. Functions of MSC The central component of the Network Subsystem is the MSC. primary functions of an MSC include the following: Switching and call routing: Routing of calls between GSM users and PSTN users. Service provisioning: Supplementary services are provided and managed by a MSC. In addition, the SMS service is handled by MSC’s. Charging: The MSC performs billing on calls for all subscribers based in its areas. When the subscriber is roaming elsewhere, the MSC obtains data for the call billing from the visited MSC. Service provisioning: Gateway to SMS between SMS centers and subscribers. Communication with HLR: The primary occasion on which an MSC and HLR communicate is during the set-up of a call to an MS, when the HLR requests some routing information from the MSC.  Communication with the VLR: Associated with each MSC is a VLR, with which it communicates for subscription information, especially during call set-up and release. Communication with other MSC’s: It may be necessary for two MSC’s to communicate with each other during call setup or handovers between cells belonging to different MSC’s.
  39. 39. Cont….. Control of connected BSC’s: As the BSS acts as the interface between the MS’s and the SS, the MSC has the function of controlling the primary BSS node: the BSC. Each MSC may control many BSC’s, depending on the volume of traffic in a particular MSC service area. An MSC may communicate with its BSC’s during, for example, call set-up and handovers between two BSC’s. Direct access to Internet services: Traditionally, an MSC accessed the Internet nodes of an Internet Service Provider (ISP) via existing networks such as the PSTN. GMSC: It`s node that interconnected two network. EX: Calls to and from one network to another network. Either MS to MS and MS to fixed line service.
  40. 40. Functions of HLR The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. Both VLR and HLR can be implemented in the same equipment in an MSC. Data in HLR: IMSI, MS-ISDN number. Category of MS. Roaming restriction ( allowed or not ). Supplementary services like call forwarding. The information stored includes:  Subscriber identity (i.e. IMSI, MSISDN) . Subscriber supplementary services. Subscriber location information (i.e. MSC service area). Subscriber authentication information.
  41. 41. Functions of VLR It`s always integrated with MSC. VLR database which contains information about subscribers currently being in the service area of the MSC/VLR. The VLR database is temporary, in the sense that the data is held as long as the subscriber is within its service area. When a mobile station roams into a new MSC area, the VLR connected to that MSC will request data about the mobile station from the HLR.  if the mobile station makes a call, the VLR will have the information needed for call setup without having to interrogate the HLR each time. VLR assigns TMSI which keeps on changing. Data in VLR: IMSI & TMSI. MSRN. Location Area. MS category. Authentication Key
  42. 42. Functions of AUC The authentication centre is a protected database. The authentication centre provide security information to the network. AUC is connected to HLR which provides it with authentication parameters and ciphering keys used to ensure network security. To perform subscriber authentication and to establish ciphering procedures on the radio link between the network and MS. Information provided is called a TRIPLET consists of: RAND(Non Predictable Random Number) SRES(Signed Response) Kc(ciphering Key).
  43. 43. Functions of EIR EIR is used for security reasons. The equipment identification procedure uses the identity of the equipment itself (IMEI) to ensure that the MS terminal equipment is valid. This data base stores IMEI for all registered mobile equipments and is unique to every ME. White list : IMEI, assigned to valid ME. Black list : IMEI reported stolen.  Gray list : IMEI having problems like faulty software, wrong make of equipment etc.
  44. 44. GSM Channels Physical Channel: one time slot on one carrier is called physical channel. Logical Channel: Information carried by physical channel is called logical channel.
  45. 45. Functions of Broadcast channel CHANNEL DIRECTION FUNCTION BCCH 1.GSM band & frequency hopping 2. LAI, RACH Point to Multipoint(Down link) parameters 3.Neighbouring infromation FCCH To communicate BTS MS must Point to Multipoint(Down link) tune to the BTS freq, It`s used MS for freq correction SCH Point to Multipoint(Down link) SCH is used to time synchronize the MS, This channel carries the TDMA frame.
  46. 46. Functions of common control channel CHANNEL DIRECTION FUNCTION PCH Point to Multipoint(Down link or Uplink) 1.Downlink direction for paging MS. 2.Incoming call purpose PCH is used AGCH Point to Multipoint(Down link) 1.MS request a call. 2. Connection is allowed via AGCH RACH MS wants to make call, Point to Multipoint(Up link) receive call, SMS, LAI the MS uses RACH.
  47. 47. Functions of dedicated control channel CHANNEL SACCH FACCH SDCCH DIRECTION FUNCTION Point to point 1.Always used with TCH(or)SDCCH.2.It`s only for non-urgent&periodically.3.Txn of signalling data, radio link measur, transmit power control Point to point 1.Used for emerging procedures. 2.It`s require for call setup&release Point to point 1.It carries all signalling b/w BTS&MS when no TCH allocated.2. It`s used for LAI, subscriber AUC,ciphering initiation, equipment validation.
  48. 48. Mobile Originating Call A call is originated from a MS as follows, The MS uses RACH (Random Access Channel) to ask for a signaling channel.  The BSC/TRC allocates a signaling channel, using AGCH (Access Grant Channel).  The MS sends a call set-up request via SDCCH (Stand alone Dedicated Control Channel) to the MSC/VLR. Over SDCCH all signaling preceding a call takes place. This includes: Marking the MS as “active” in the VLR The authentication procedure Equipment identification Sending the B-subscriber’s number to the network Checking if the subscriber has the service “Barring of outgoing calls” activated
  49. 49. Cont…. The MSC/VLR instructs the BSC/TRC to allocate an idle TCH. The BTS and MS are told to tune to the TCH. The MSC/VLR forwards the B–number to an exchange in the PSTN, which establishes a connection to the subscriber. If the B-subscriber answers, the connection is established. videosEricsson The History of Wireless Communication.wmv
  50. 50. 2G/3G Architecture Mobile Station ME SIM Base Station Subsystem BTS BSC Network Subsystem MSC/ VLR EIR Other Networks GMSC PSTN HLR AUC PLMN RNS ME USIM SD + Node B RNC SGSN GGSN Internet UTRAN Note: Interfaces have been omitted for clarity purposes.
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×