3G NEWORK OPTIMIZATION DOCUMENT

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3G NEWORK OPTIMIZATION DOCUMENT

  1. 1. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 1 Dept. of ECE (2013-2014) 1. MOBILE COMMUNICATION 1.1 Revolution in telecommunication The telephone has long been important in modern living, but it use has been constrained by connecting wires. The advent of mobile radio telephony and particularly the cellular radio has removed this restriction and led to explosive growth in mobile throughout the world. The phone is really on move now.With the phenomenal and unprecedented growth of more than forty fold in just ten years a strong demand for mobile cellular services has created an industry which now accounts for more than one third of all telephone lines. 1.2 Concept of mobile communication The first wire line telephone system was introduced in the year 1877.Mobile communication systems as early as 1934 were based on Amplitude Modulation (AM schemes and only certain public organizations maintained such systems. The development of Frequency Modulation (FM) technique by Edwin Armstrong, the mobile radio communication systems began to witness many new changes. Mobile telephone was introduced in the year 1946. However, during its initial three and a half decades it found very less market penetration owing to high costs and numerous technological drawbacks. But with the development of the cellular concept in the 1960s at the Bell Laboratories, mobile communications began to be a promising field of expanse which could serve wider populations. 1.3Mobile communication objectives The important objectives of mobile communications are Anytime anywhere communication Mobility& Roaming High capacity and subs density Efficient use of radio spectrum
  2. 2. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 2 Dept. of ECE (2013-2014) Table 1.1: Different generations- Analog and Digital systems 1946-1960 1980 1990 2000 Appearance 1G 2G 3G Analog Digital Digital Multi Standard Multi Standard Unified Standard Terrestrial Terrestrial Terrestrial &Satellite The features and benefits expected in the new system  Superior speech quality  Low terminal, operational, and service costs  A high level of security  International Roaming  Support of low terminal hand portable terminals  A variety of new services and network facilities. 1.4Constraints in Implementation A host of services like teleservices supplementary services and value added services are being promised by GSM Networks. There are certain impairments in realizing an effective mobile communication system which has to meet the twin objectives of quality and capacity. (a) Radio frequency reuse High spectrum efficiency should be achieved at reasonable cost. The bandwidth on radio interface i.e. between the user equipment and the radio transceiver is to be managed effectively
  3. 3. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 3 Dept. of ECE (2013-2014) to support ever increasing customer base with very limited number of radio carriers. For high BW services e.g. MMS as the GSM evolves towards 3G, more spectrums is demanded. (b) Multi path radio environment The most significant problem in mobile radio systems is due to the channel itself. In mobile radio systems, indeed,it is rare for there to exist one strong line of sight path between transmitter and receiver. Usually several significant signals are received by reflection and scattering from buildings etc. .And then they are Multiple paths from transmitter receiver. Fig 1.1 Multipath radio environment The signals on these paths are subject to different delays phase shifts and Doppler shifts and at the receiver in random phase relation to one another. The interferences between these signals give rise to a number of deleterious effects. The most important of these are Fading and Dispersion. Fading is due to the interference of multiple signals with random relative phase that causes variations in the amplitude of the received signal. This will increase the error rate in digital system since errors will occur when the signal-to noise ratio drops below certain threshold.
  4. 4. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 4 Dept. of ECE (2013-2014) Dispersion is due to differences in the delay of the various paths, which disperses transmitted pulses in time. If the variation of delay is comparable with the symbol period delayed signals from an earlier symbol may interface with the next symbol causing Inter- symbol interference (ISI). (c) Mobility management Mobility management is concerned with how the network supports this function. When a call is made to mobile customer the network must be able to locate the mobile customer. Network attachment process which includes a location updating process is the answer for mobility management. In the location update process , the network databases are updated dynamically so that the mobile can be reached to offer the services if this process is not done efficiently it will result in poor call management and network congestion. (d) Services International roaming shall be provided. Advanced PSTN services should be provided consistent with ISDN services at limited bit rates only. Encryption should be used to improve security for both the operators and the customers. (f) Cost The system parameters should be chosen to limit costs particularly mobiles and handsets .In a competitive environment cost is the deciding factor for the survival of an operator.
  5. 5. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 5 Dept. of ECE (2013-2014) 2. BANDWIDTH MANAGEMENT 2.1 INTRODUCTION Radios move information from one place to another over channels and radio channel is an extraordinarily hostile medium to establish and maintain reliable communications. The channelis particularly messy and unruly between mobile radios. All the schemes and mechanisms we use to make communications possible on the mobile radio channel with some measure of reliability between a mobile and its base radio station are called physical layer or the layer1 procedures. The mechanisms include modulation, power control, codingtiming, and host of other details that manage establishment and maintenance of the channel the radio channel has to be fully exploited for maximum capacities and optimum quality of service. Band width is a scarce natural resource. The bandwidth has to be managed for maximum capacity of the system and interference free communications. The spectrum availability for an operator is very limited .The uplink or downlink spectrum is only 25 MHz, out of this 25 MHz, 124 carriers of each 200 kHz are generated. These carriers are to be shared amongst different operators. And as a result each operator gets only a few tens of carriers making a spectrum management a challenging area. 2.2 Cellular structures and Frequency Reuse Traditional mobile service was structured similar to television broadcasting: One very powerful transmitter at the highest spot in area would broadcast in anarea radius of up to fifty kilometers. The scenario changes as the mobile density as well as coverage area grows. The answer to tackle the growth is the extensions based on addition of new cells.Thecellular concept structured the mobile telephone network in a different way.Instead of using one powerful transmitter many low-powered transmitter were placed throughout a coverage area. For example, by dividing metropolitan region into one hundred different areas (cells) with low power transmitters using twelve conversations (channels) each, the system capacity could theoretically be increased from twelve to thousands of conversations using one hundred low power transmitters while reusing the frequenciesThe cellular concept employs variable low power levels, which allows cells to be sized according to subscriber density and demand of a given
  6. 6. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 6 Dept. of ECE (2013-2014) area. As the populations grow, cells can be added to accommodate that growth. Frequencies used in one cell cluster can be reused in other cells. Conversations can be handed over from cell to cell to maintain constant phone service as the user moves between cells. Cells: A cell is the basic geographic unit of cellular system. The term cellular comes from the honeycomb areas into which a coverage region is divided. Cells are base stations transmitting over small geographic areas that are represented as hexagons. Each cell size varies depending upon landscape. Because of the constraint imposed by natural terrain and man-made structures, the true shape of cell is not a perfect hexagon. (a) Cellular System Characteristics The distinguishing features of digital cellular systems compared to other mobile radio systems are: Small cells A cellular system uses many base stations with relatively small coverage radii (on the order of a 100 m to 30 km). Clusters and Frequency reuse The spectrum allocated for a cellular network is limited. As a result there is a limit to the number of channels or frequencies that can be used. A group of cells is called a cluster. All the frequencies are used in a cluster and no frequency is reused with in the cluster. And the total set of frequencies is repeated in the adjacent cluster. Like that the total service area, i.e. may be a country or a continent, can be served with a small group of frequencies. Frequency reuse is possible because the signal fades over the distance and hence it can be reused .For this reason each frequency is usedsimultaneously by multiple base-mobile pairs; located at geographically distant cells. This frequency reuse allows a much higher subscriber density per MHz of spectrum than other systems. System capacity can be further increased by reducing the cell size (the coverage area of a single base station), down to radii as small as 200 m.
  7. 7. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 7 Dept. of ECE (2013-2014) Small, battery-powered handsets In addition to supporting much higher densities than previous systems, this approach enables the use of small, battery-powered handsets with a radio frequency that is lower than the large mobile units used in earlier systems. Performance of handovers In cellular systems, continuous coverage is achieved by executing a "handover" (the seamless transfer of the call from one base station to another) as the mobile unit crosses cell boundaries. This requires the mobile to change frequencies under control of the cellular network. (b) Co channel cells and interference Radio channels can be reused provided the separation between cells containing the same channel set is far enough apart so that co-channel interference can be kept below acceptable levels most of the time. Cells using the same channel set are called Co-channel cells. Co-channel cells interfere with each other and quality is affected. The following figure shows an example. Within the service area (PLMN), specific channel sets are reused at a different location (another cell). In the example, there are 7 channel sets: A through G. Neighboring cells are not allowed to use the same frequencies. For this reason all channel sets are used in a cluster of neighboring cells. As there are 7 channel sets, the PLMN can be divided into clusters of 7 cells each. The figure shows three clusters. Co-channel interference Frequencies can be reused throughout a service area because radio signals typically attenuate with distance to the base station (or mobile station). When the distance between cells using the same frequencies becomes too small, co-channel Interference might occur and lead to service interruption or unacceptable quality of service. As long as the ratio Frequency reuse distance = DNCell radius Is greater than some specified value, the ratio
  8. 8. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 8 Dept. of ECE (2013-2014) Received radio carrier power =C/I Received interferer radio carrier power will be greater than some given amount for small as well as large cell sizes; when all signals are transmitted at the same power level. The average attenuation of radio signals with distance in most cellular systems is a reduction to about 1/16 of the received power for every doubling of distance (1/10000 per decade).The frequency reuse distance known as separation distance is also known as the signal-to-noise ratio. The figure on the opposite page shows the situation. At the base station, both signals from subscribers within the cell covered by this base station and signals from subscribers covered by other cells are received. Interference is caused by cells using the same channel set. The ratio D/R needs to be large enough in order for the base station to be able to cope with the interference. A co-channel interference factor Q is definedAs Q=D/R = v 3K where D is Frequency reuse distance, Ris the cell radius and K is the reuse factor or the number of cells in a cluster K=reuse factor=No of cells in a cluster Q=D/R = v 3K Q is more — Sys quality high If K is more no of cells in a clutters is more No of channels per cell less Traffichandling capacity low Fig 2.1: Frequency reuse
  9. 9. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 9 Dept. of ECE (2013-2014) 3. 3G UMTS NETWORK ARCHITECTURE 3G has become an umbrella term to describe cellular data communications with a target data rate of 2 M bits/sec. The ITU originally attempted to define 3G in its IMT-2000 (International Mobile Communications-2000) specification, which specified global wireless frequency ranges, data rates, and availability dates. However, a global standard was difficult to implement due to different frequency allocations around the world and conflicting input. So, three operating modes were specified. In general, a 3G device will be a personal, mobile, multimedia communications device that supports speech, color pictures, and video, and various kinds of information content. There is some doubt that 3G systems will ever be able to deliver the bandwidth to support these features because bandwidth is shared. However, 3G systems will certainly support more phone calls per cell 3.1 Introduction to UMTS The 3rd generation mobile communication system (3G) is put on agenda when the 2nd generation (2G) digital mobile communication market was significantly evolving. The 2G mobile communication systems have the following disadvantages: limited frequency spectrum resources, low frequency spectrum utilization and weak support for mobile multimedia services (providing only speech and low-speed data services). Also, there was incompatibility between 2G systems. The 2G mobile communication system has a low system capacity hardly meeting the demand for high speed bandwidth services and impossible for the system to implement global roaming. Therefore, the 3G communication technology is a natural result in the advancement of 2G mobile communication technology. As the internet data services are becoming increasingly popular nowadays, the 3G communication technology opens the door to a brand new mobile communication world. In addition to clear voice services, it allows users to conduct multimedia communications with their personal mobile terminals, for example, internet browsing, multimedia database access, real time stocks quotes query, videophone, mobile e-commerce, interactive games, wireless personal audio
  10. 10. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 10 Dept. of ECE (2013-2014) player, video transmission, knowledge acquisition and entertainments. Some unique features include location related services, which allows the users to know about their surroundings anytime, anywhere, for example, block map, locations of hotels, supermarkets and weather forecasting. The 3G mobile phone has become a good assistant to people‘s life and work. 3.2 History Discussion of a potential successor system for GSM started in ETSI and other standard developing organizations already in the late 1980, even before any second-generation system was in commercial operation. The ETSI-term for the future system was Universal MobileTelecommunications System (UMTS). Simultaneously, the International Telecommunication (ITU) also started discussions on a potential future mobile system initially referred to as Future Public Land Mobile System (FPLMTS) and started to specify a set of system requirements. Due to the huge world-wide success of GSM, the interest among European network operatorsand manufacturers to consider a completely new system was rather low until to the mid-1990s. Only after the ITU has taken the initiative to formulate a concrete roadmap towards a new mobilesystem to be deployed in the early 2000s, the specification activities for UMTS in ETSI wereramped up in 1995. The ITU term for the future 3G system was later changed to IMT-2000, International Telecommunications System for the 2000s. As part of the roadmap, a deadline for submission ofproposals for IMT-2000 by the regional standardization development organizations was agreed to be in July 1998.In January 1998 ETSI selected two radio transmission technologies (from originally 4 different proposals) for UMTS terrestrial radio access (UTRA), referred to as UTRA FDD and UTRA TDD, which were submitted to ITU as candidates for IMT-2000. The proposals included a number of different Wideband CDMA (WCDMA) based Radio access technologies, from ETSI, TTC/ARIB (Japan), TTA (Korea), ANSI T1 (USA) and TIA (USA), which can be grouped into two types. The one type of proposals requires synchronized base stations and is building up on the IS-95 2G radio transmission technology. The other group of concepts does not rely on base station synchronization.
  11. 11. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 11 Dept. of ECE (2013-2014) Table 3.1: Terrestrial radio transmission technologies proposed by ITU By the end of 1998 two specification development projects were founded by the regional Standardization organizations, 3GPP (3rd Generation Partnership Project) and 3GPP2. The goal of both 3GPP and 3GPP2 was to merge a number of the W-CDMA based proposals into a single one. 3GPP2 was concerned with the IS-95 based systems. The split of standardization activities into two camps was partly caused by a dispute on Intellectual Property Rights (IPR) on W- CDMA technology between various telecom manufacturers. After these IPR issues were resolved in mid-1999, the members of 3GPP and 3GPP2 agreed on a harmonized global IMT- 2000 CDMA proposal. This agreement then paved the way for a harmonized overall concept of an ITU IMT-2000 family of 3G systems.
  12. 12. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 12 Dept. of ECE (2013-2014) Fig 3.1:ITU EMT-2000 family of 3G system The 3G mobile communication system, IMT-2000, is the general term for the next generation communication system proposed by ITU in 1985, when it was actually referred to as Future public Land Mobile Telecommunications System (FPLMTS). In 1996, it was officially renamed to IMT-2000.The 3G mobile communication technologies enjoys the integrated bandwidth network service as far as it can to the mobile environment, transmitting multimedia information including high quality images at rates up to 10Mbps. Comparing with the existing 2G system, the 3G system has the following characteristics as summarized below: 1. Support for multimedia services, especially internet services 2. Easy transition and evolution 3. High frequency spectrum utilization Currently, the three typical 3G mobile technology communication standards in the world are CDMA2000, WCDMA and TD-SCDMA. CDMA2000 and WCDMA work in FDD mode whereas TD-SCDMA works in TDD mode, where uplink and downlink of the system work in different timeslots of the same frequency.
  13. 13. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 13 Dept. of ECE (2013-2014) The 3G mobile communication is designed to provide diversified services and high quality multimedia services. To achieve these purposes, the wireless transmission technology must meet the following requirements: 1. High speed transmission to support multimedia services Indoor environment : > 2 Mbps Outdoor walking environment : 384 kbps Outdoor vehicle moving : 144 kbps 2. Allocation of transmission rates according to needs 3. Accommodation to asymmetrical needs on the uplink and downlink In the concept evaluation of the 3G mobile communication specification proposals, the WCDMA technology is adopted as one of the main stream 3G technologies due to its technical advantages. 3.2.1 Frequency spectrum allocation: The frequency bands allocated for initial operation of IMT-2000/UMTS systems is shown in figure 1.4. In Europe there is one paired frequency band in the range 1920 –1980 MHz and 2110 –2170 MHz to be used for UTRA FDD and there are two unpaired bands from 1900 – 1920 MHz and 2010 – 2025 MHz intended for operation of UTRA TDD. In the USA 3G systems shall initially be operated in the PCS band which is already partly used for 2G systems. MSS refers to spectrum reserved for 3G mobile satellite systems (1980 - 2010 MHz and 2170 – 2200 MHz). The PCS band in the USA was already divided into chunks of 5 MHz and mostly sold in form of 2×5 MHz paired band to PSC network operators before any 3G systems were proposed. This situation in the USA has imposed the requirement that it must be possible to operate a 3G system within a 2 × 5 MHz paired frequency band. The UMTS band in Europe is therefore divided into twelve 5 MHz paired frequency slots, suitable for UTRA FDD, and four plus three 5 MHz unpaired frequency slots suitable for UTRA TDD mode. In Germany the UMTS spectrum will be auctioned starting in July 2000. One operator is allowed to acquire at least two, at most three paired bands. Therefore there will be initially between 4 and 6 UMTS operators in Germany.
  14. 14. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 14 Dept. of ECE (2013-2014) In May 2000 further frequency bands for UMTS/IMT-2000 was identified by the ITU World Radio Conference (WRC-2000). These bands (more than 160 MHz additional spectrum) shall ensure future extension of UMTS. Fig 3.2 spectrum assigned to operation of 3G system 3.2.2 UMTS (Release 99) Architecture: Fig 3.3 UMTS (release99) architecture
  15. 15. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 15 Dept. of ECE (2013-2014) The Universal Mobile Telecommunication System (UMTS) is a 3G mobile communication system adopting WCDMA air interface. Therefore, the UMTS is usually called a WCDMA system. In terms of functions, the network units comprise the radio access network (RAN) and core network (CN). The RAN accomplishes all the functions related to radio communication. The CN handles exchange and routing of all the calls and data connections within the UMTS with external networks. The RAN, CN and the User equipment (UE) together constitute the whole UMTS. 3.2.3 UE (USER EQUIPMENT): The UE is equipment which can be vehicle installed or hand portable. Through the Uu interface, the UE exchanges data with network equipment and provides various CS and PS domain services, including common voice services, broadband voice services, mobile multimedia services, and applications ( such as email, WWW browse and FTP). 3.2.4 UTRAN (UMTS Terrestrial Radio Access Network): The UMTS terrestrial radio access network (UTRAN) comprises node B and radio network Controller (RNC). 1.) Node B1. At the base station(wireless transceiver) in the WCDMA system, the node B is composed of the wireless transceiver and baseband processing part, connected with the RNC through standard Iub interface, node B processes the Un interface physical layer protocols. It provides the functions of spectrum spreading/decoding and mutual conversation between baseband signals and radio signaling. 2.) RNC The RNC manages various interfaces, establishes and releases connections, performs handoff and macro diversity/combination and manages and controls radio resources. It connects with the MSC and SGSN through lu interface. The protocol between UE and UTRAN is terminated here.
  16. 16. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 16 Dept. of ECE (2013-2014) The RNC that controls Node B is called controlling RNC(CRNC).The CRNC performs load control congestion control of the cells it serves and implements admission control of cells it serves and implements admissions control and code word allocation for the wireless connections to be established. If the connection between a mobile subscriber and the UTRAN uses many RNS resources, the related RNC has two independent logical functions: Serving RNC (SRNC). The SRNC terminates the transmission of subscriber data and the Iu connection and RANAP signaling to/from the CN. It also terminates the radio resource controlling signaling (i.e. the signaling protocol between UE and UTRAN). In addition, the SRNC performs L2 processing of the data sent to/from the radio interface and implements some basic operations related to radio resources management. Drift RNC (DRNC) - All other RNC‘s except SRNC are called as DRNCs. They control the cells used by UE‘s. 3.3 CORE NETWORK (CN): The CN is the in charge of connections with other networks as well as the management and communication with UE‘s. The CN can be divided into CS domain and PS domain from the aspect of logic. The CS domain equipment refers to the entities that provide circuit connection or related signaling connections for subscriber services. The specific entities in the CS domain include: 1. Mobile switching center (MSC) 2. Gateway mobile switching Centre (GMSC) 3. Visitor location register (VLR) 4. Interworking function (IWF) The PS domain provides packet data services to subscribers. The specific entities in the PS domain include: 5. Serving GPRS support node (SGSN) 6. Gateway GPRS support node (GGSN) Other equipment such as the Home Location Register (HLR) or HSS, Authentication Centre (AUC) and Equipment Identity Register (EIR) are shared by CS domain and PS domain.
  17. 17. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 17 Dept. of ECE (2013-2014) 3.3.1 Functions of core network 1. MSC/VLR As the functional node in the CS domain of the WCDMA core network, the MSC/VLR connects with the UTRAN through Iu CS interface, with external networks (PSTN, ISDN and other PLMNs) through PSTN/ISDN interface, with the HLR/AUC through C/D interface, with the MSC/VLR, GMSC or SMC through E interface, with the SCP through CAP interface and with the SGSN through Gs interface. The MSC/VLR accomplishes call connection, mobility management, authentication and encryption in the CS domain. 2. GMSC As the gateway node between the CS domain of WCDMA network and external networks, the GMSC is an optional entity. It connects with the external networks (PSTN, ISDN and other PLMNs) through PSTN/ISDN interface and with the SCP through CAP interface. The GMSC accomplishes the incoming and outgoing routing of the visited MSC (VMSC). 3. SGSN As the functional node in the PS domain of WCDMA core network, the SGSN connects with the UTRAN through Iu_PS interface, with GGSN through Gn/Gp interface, with the HLR/AUC through Gr interface, with the MSC/VLR through Gs interface, with SCP through CAP interface, with the SMC through Gd interface, with the CG through Ga interface and with SGSN Gn/Gp interface. The SGSN accomplishes the routing forward, mobility management, session management, authentication and encryption in PS domain. 4. GGSN The GGSN connects with the SGSN through Gn interface and with the external data networks (internet/intranet) through Gi interface. The GGSN provides routes to the data packets between the WCDMA network and external data networks and encapsulates these data packets. The major functions of the GGSN is to provide
  18. 18. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 18 Dept. of ECE (2013-2014) interface to the external IP packet-based network, thus the UEs can access the gateway of the external packet based network. To the external networks, the GGSN seems like the IP router that can be used to address all the mobile subscribers in the WCDMA network. It exchanges routing information with external networks. 5. HLR The HLR connects with the VMSC/VLR or GMSC through C interface, with the SGSN through Gr interface, and with the GGSN through Gc interface. The HLR stores subscriber subscription information, supports new services and provide enhanced authentication. 3.3.2 Teleservices and supplementary services A basic requirement defined for UMTS is that it needs to support all GSM teleservices, e.g. speech, emergency call and short message service (SMS). Below, the most important teleservices and supplementary services are listed and described briefly. 3.3.2.1Telephony Speech: Telephone speech service in UMTS is supported by employing the Adaptive Multi-Rate (AMR) speech codec. This Codec is compatible with the speech codecs presently used in GSM systems and it will also be introduced in GSM in the near future. It shall operate with no discernible loss of speech on handover between the GSM access network and the UTRAN. Emergency Call: UMTS Release ‗99 shall support an emergency call teleservice. This is just a special case of normal speech service. It requires to work even without USIM included in the UE. Teleconferencing: Teleconferencing provides the ability for several parties to be engaged in a speech communication. This service can be established with ordinary telephone service in combination with supplementary service, allowing the user to establish multiparty calls. Voice-band-data: Support of modems supporting user rates of 14.4 kbps or more. 3.3.2.2 Sound and Video telephony Wideband-speech: Speech service or radio sound at 0 – 7 kHz bandwidth (future UMTS release) High-Quality Audio: Audio service with Compact Disk quality (future UMTS release)
  19. 19. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 19 Dept. of ECE (2013-2014) Video telephone: Ability for two-way speech and image communications. Video Conference: Ability for multi-party speech and image communications. Video Surveillance/Monitoring: Provides the transmission of image and sound in one direction. 3.3.2.3 Tele-action services: Telemetric services: Services for e.g. remote control, remote terminal, credit authorization requiring low bit rate per transaction but possibly fast response time. 3.3.2.4 Message handling services Short Message Service: A means for sending messages of limited size to and from mobile terminals which makes use of a Service Center which acts as store and forward center for short messages (supported by GSM and UMTS release 99). Voice Mail: Voice mail enables calling users to record a voice message against the called user‘s identity under a variety of conditions (e.g. called user busy, not answering, and not reachable). Electronic mail: In their simplest form electronic mail service provide the ability to transfer textual messages between users via a variety of intervening networks. Electronic mail systems may also provide format conversion enabling text and data to be converted from one format into another, including media conversion, e.g. mail send as text but received as voice. 3.3.2.5 Facsimile service Store-and-Forward telefax: A service, where a file or message transfer program is used to transfer text or images from a mobile terminal to a store and forward unit for subsequent delivery to the facsimile machine in the PSTN/ISDN. The user (or the user's PC) may receive notification of successful delivery of the fax. Fax messages from PSTN/ISDN to mobile terminals are stored in a store-and-forward unit (service center). The user retrieves the fax message with a file or message transfer program from the store-and-forward unit. The mobile terminal may be notified that a fax message is available. Note that this service also belongs to the category of messagehandling services (supported by GSM and UMTS release 99). End-to-End telefax: A fax service using an end-to-end fax session between a PSTN/ISDN fax machine and a mobile terminal. This service shall work end-to-end such that a sender on the PSTN is aware of whether or not the fax has succeeded, and such that a mobile sender is aware of whether or not the fax has succeeded. From the user perspective the end-to-end fax service must look and feel like a T.30 based fax service. The end-to-end service may work with ordinary
  20. 20. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 20 Dept. of ECE (2013-2014) T.30 based fax machines at the mobile end using a mobile fax adapter with a modem that terminates the analogue 2-wire connection from the fax machine (supported by GSM and UMTS release 99). 3.3.2.6 Broadcast Services (Message) Cell Broadcast Service (CBS): Provides transmission of a message to all users within a specified geographic area which have a subscription to this service. Multicast service: A data broadcast service for a specified group of users within a specified geographic area. 3.3.2.7 Supplementary Services: Supplementary services modify or supplement a basic telecommunication service. Consequently, it cannot be offered to a customer as a standalone service. It must be offered together with or in association with a basic telecommunication service. UMTS will support GSM Release '99 supplementary services and many further extensions. Below, some examples of supplementary services are listed:  call barring,  call forwarding,  call hold,  conference calling,  in call modification (dialing),  handling of closed user groups,  Credit card calling. 3.4 Multimedia Services UMTS shall support multimedia services and provide the necessary capabilities. Multimedia services combine two or more media components (e.g. voice, audio, data, video, pictures) within one call. A multimedia service may involve several parties and connections (different parties may provide different media components) and therefore flexibility is required in order to add and delete both resources and parties. Multimedia services are typically classified as interactive or distribution services. Interactive services are typically subdivided into conversational, messaging and retrieval services:
  21. 21. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 21 Dept. of ECE (2013-2014) Conversational services: Theseare real time (no store and forward), usually bi-directional where low end to end delays (< 100 ms) and a high degree of synchronization between media components (implying low delay variation) are required. Video telephony and video conferencing are typical conversational services. Messaging services: Theseoffer user to user communication via store and forward units (mailbox or message handling devices). Messaging services might typically provide combined voice and text, audio and high resolution images. Retrieval services: Theseenable a user to retrieve information stored in one or many information center. The start at which an information sequence is sent by an information center to the user is under control of the user. Each information center accessed may provide a different media component, e.g. high resolution images, audio and general archival information. 3.4.1 Distributional services Distribution services are typically subdivided into those providing user presentation control and those without user presentation control. Distribution services without user control: Theseare broadcast services where information is supplied by a central source and where the user can access the flow of information without any ability to control the start or order of presentation e.g. television or audio broadcast services. Distribution services with user control: Theseare broadcast services where information is broadcast as a repetitive sequence and the ability to access sequence numbering allocated to frames of information enables the user (or the user‘s terminal) to control the start and order of presentation of information. 3GPP specifications shall support single media services (e.g. telephony) and multimedia services (e.g. video telephony). All calls shall have potential to become multimedia calls and there shall be no need to signal, in advance, any requirement for any number of multimedia components. However, it shall be possible to reserve resources in advance to enable all required media components to be available.
  22. 22. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 22 Dept. of ECE (2013-2014) 3.4.2 Bearer services Circuit switched data: Circuit switched data services and "real time" data services shall be provided for interworking with the PSTN/ISDN so that the user is unaware of the access network used (UMTS and GSM access network or handover between access networks). Both transparent (constant delay) and non-transparent (zero error with flow control) services shall be supported. These data services shall operate with minimum loss of data on handover between the GSM access network and the UTRAN. Packet switched data: Packet switched data services shall be provided for interworking with packet networks such as IP-networks and LANs. The standard shall provide mechanisms which ensure the continuity of packet based services upon handover e.g. between GSM and UMTS. Fig 3.4 3G UMTS Generation
  23. 23. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 23 Dept. of ECE (2013-2014) 4.HIGHSPEED PACKET ACCESS 4.1Overview The introduction of High-Speed Downlink Packet Access, (HSDPA), implies a major extension of the WCDMA radio interface, enhancing the WCDMA downlink packet-data performance and capabilities in terms of higher peak data rate, reduced latency and increased capacity. This is achieved through the introduction of several of the techniques described in Part II, including higher-order modulation, rate control, channel-dependent scheduling, and hybrid ARQ with soft combining. 4.1.1Shared-channel transmission Akey characteristic ofHSDPAis the use of Shared-Channel Transmission. Shared channeltransmission implies that a certain fraction of the total downlink radioresources available within a cell, channelization codes and transmission powerin case of WCDMA, is seen as a common resource that is dynamically sharedbetween users, primarily in the time domain. The use of shared-channel transmission,inWCDMAimplemented through the High-Speed Downlink Shared Channel(HS-DSCH) as described below, enables the possibility to rapidly allocate a largefraction of the downlink resources for transmission of data to a specific user. Thisis suitable for packet-data applications which typically have burst characteristicsand thus rapidly varying resource requirements. TheHS-DSCH code resource consists of a set of channelization codes of spreadingfactor 16, where the number of codes available forHS-DSCH transmission is configurable between 1 and 15. Codes not reserved forHS-DSCH transmission are used for other purposes, for example related control signaling, MBMS services, or circuit-switched services. The dynamic allocation of the HS-DSCH code resource for transmission to a specific user is done on 2 ms TTI basis. The use of such a short TTI for HSDPA reduces the overall delay and improves the tracking of fast channel variations exploited by the rate control and the channel- dependent scheduling as discussed below. In addition to being allocated a part of the overall code resource, a certain part of the total available cell power should also be allocated for HS-DSCH transmission. Note that the HS-DSCH is not power controlled but rate controlled as discussed
  24. 24. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 24 Dept. of ECE (2013-2014) below. This allows the remaining power, after serving other channels, to be used for HS-DSCH transmission and enables efficient exploitation of the overall available power resource. Fig 4.1 Channelization codes in HSDSCH Transmission 4.1.2 Channel-dependent scheduling Scheduling controls to which user the shared-channel transmission is directed at a Given time instant. The scheduler is a key element and to a large extent determines The overall system performance, especially in a highly loaded network. In each TTI, the scheduler decides to which user(s) the HS-DSCH should be transmittedand, in close cooperation with the rate-control mechanism, at what data rate. Since the radio conditions for the radio links to different UEs within a cell typically vary independently, at each point in Time there is almost always a radio link whose channel quality is near its peak. As this radio link is likely to have good channel quality, a high data rate can be used for this radio link. This translates into a high system capacity. The gain obtained by transmitting to users with favorable radio-link conditions is commonly known as multi-user diversity and the gains are larger, the larger the channel variations and the larger the number of users in a cell. Thus, in contrast to the traditional view that fast fading is an undesirable effect that has to be combated, with the
  25. 25. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 25 Dept. of ECE (2013-2014) possibility for channel-dependent scheduling fading is potentially beneficial and should be exploited. In addition to the channel conditions, traffic conditions are also taken into account By the scheduler. For example, there is obviously no purpose in scheduling a user with no data awaiting transmission, regardless of whether the channel conditions are beneficial or not. Furthermore, some services should preferably be given higher priority. As an example, streaming services should be ensured a relatively constant long-term data rate while background services such as file download have less stringent requirements on a constant long-term data rate. Fig 4.2 channel dependent scheduling for HSDPA 4.1.3 Rate control and higher-order modulation For HSDPA, rate control is implemented by dynamically adjusting the channel coding rate as well as dynamically selecting between QPSK and 16QAM modulation. Higher-order modulation such as 16QAM allows for higher bandwidth utilization than QPSK, but requires higher received Eb/N0. Consequently, 16QAM is mainly useful in advantageous channel conditions. The data rate is selected independently for each 2 ms TTI by the NodeB and the rate control mechanism can therefore track rapid channel variations. 4.1.4 Hybrid ARQ with soft combining Fast hybrid ARQ with soft combining allows the terminal to request retransmission of erroneously received transport blocks, effectively fine-tuning the effective code rate and compensating for errors made by the link-adaptation mechanism. The terminal attempts to decode each transport block it receives and reports to the NodeB its success or failure 5 ms after the reception of the transport block. This allows for rapid retransmissions of unsuccessfully
  26. 26. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 26 Dept. of ECE (2013-2014) received data and significantly reduces the delays associated with retransmissions compared to Release 99. Soft combining implies that the terminal does not discard soft information in case It cannot decode a transport block as in traditional hybrid-ARQ protocols, but combines soft information from previous transmission attempts with the current retransmission to increase the probability of successful decoding. Incremental redundancy, IR, is used as the basis for soft combining in HSDPA that is the retransmissions may contain parity bits not included in the original transmission. It is known that IR can provide significant gains when the code Rate for the initial transmission attempts is high as the additional parity bits in theretransmission results in a lower overall code rate. Thus, IR is mainly useful inbandwidth-limited situations, for example, when the terminal is close to the basestation and the amount of channelization codes, and not the transmission power,limits the achievable data rate. The set of coded bits to use for the retransmissionis controlled by the NodeB, taking the available UE memory into account 4.1.5 Architecture From the previous discussion it is clear that the basic HSDPA techniques rely on fast adaptation to rapid variations in the radio conditions. Therefore, these techniques need to be placed close to the radio interface on the network side at the same time, an important design objective of HSDPA was to retain the Release 99 functional split between layers and nodes as far as possible. Minimization of the architectural changes is desirable as it simplifies introduction of HSDPA in already deployed networks and also secures operation in environments where not all cells have been upgraded with HSDPAfunctionality. Therefore, HSDPA introduces a new MAC sub-layer in the NodeB, the MAC-hs, responsible for scheduling, rate control and hybrid-ARQ protocol operation. Hence, apart from the necessary enhancements to the RNC such as admission control of HSDPA users, the introduction of HSDPA mainly affects the NodeB Each UE using HSDPA will receive HS-DSCH transmission from one cell, the serving cell. The serving cell is responsible for scheduling, rate control, hybrid ARQ, and all other MAC-hs functions used by HSDPA. Uplink soft handover is supported, in which case the uplink data transmission will be received in multiple cells. Mobility from a cell supporting HSDPA to a cell that is not supporting HSDPA is easily handled. Uninterrupted service to the user can be provided, albeit at a lower data rate, by using channel switching in the RNC and switch the user to a dedicated channel in
  27. 27. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 27 Dept. of ECE (2013-2014) the non-HSDPA cell. Similarly, a user equipped with an HSDPA-capable terminal may be switched from a dedicated channel to HSDPA when the user enters a cell with HSDPA support. Fig 4.3 HSDPA architecture 4.2 HSDPA vs. UMTS Various methods for packet data transmission in WCDMA downlink already exist in Release'99. The three different channels in Release'99/ Release 4 WCDMA specifications that can be used for downlink packet data are: Dedicated Channel (DCH) Downlink-shared Channel (DSCH) Forward Access Channel (FACH). The basic requirements for HSDPA are to carry high data rate in the downlink. The HSDPA technology will:
  28. 28. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 28 Dept. of ECE (2013-2014) Increase the UTRAN network capacity Reduce the round trip delay Increase the peak data rates up to 14 Mbps In order to achieve this few architectural changes have been made in the R99 architecture. The transport channel carrying the user data with HSDPA operation is denoted as the High-speed Downlink-shared Channel (HS-DSCH) known as downlink "fat pipe". As discussed above the primary motivation behind HSDPA was to achieve high data rates by not disturbing to the current UMTS architecture too much. Thus it's clear that by implementing the HSDPA the current UMTS architecture is maintained and some other features or functionalities are added on top of the existing architecture. In HSDPA (Release 5) three new transport channels are introduced. They are: HS-DSCH (High Speed Down link Shared Channel) To support the HS-DSCH Operation Two Control Channels are added HS-SCCH (High Speed Shared Control Channel) DL channel HS- DPCCH (High Speed Dedicated Physical Control Channel) UL Channel With HSDPA two fundamental features of WCDMA are disabled which is: Variable SF Fast Power Control
  29. 29. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 29 Dept. of ECE (2013-2014) These two features are replaced by Adaptive Modulation and Coding (AMC) Fast retransmission strategy (HARQ) Scheduling Algorithm 4.2.1 HS-DSCH: The High-Speed Downlink Shared Channel (HS-DSCH), is the transport channel Used to support shared-channel transmission and the other basic technologies in HSDPA, namely channel-dependent scheduling, rate control (including higher order modulation), and hybridARQwith soft combining. As discussed in the introduction and illustrated in Figure 9.1, the HS-DSCH corresponds to a set of channelization codes, each with spreading factor 16. Each such channelization code isalso known as an HS-PDSCH – High-Speed Physical Downlink Shared Channel. In addition to HS-DSCH, there is a need for other channels as well, for example for circuit-switched services and for control signaling. To allow for a trade-off between the amount of code resources set aside for HS-DSCH and the amount of code resource used for other purposes, the number of channelization codes available forHS-DSCH can be configured, ranging from 1 to 15 codes. Codes not reserved for HS-DSCH transmission are used for other purposes, for example related control signaling and circuit-switched services. The first node in the code tree can neverbe used for HS-DSCH transmission as this node includes mandatory physicalchannels such as the common pilot.Sharing of the HS-DSCH code resource should primarily take place in the timedomain. The reason is to fully exploit the advantages of channel- dependentscheduling and rate control, since the quality at the terminal varies in the time Domain, but is (almost) independent of the set of codes (physical channels) usedfor transmission. However, sharing of the HS-DSCH code resource in the codedomain is also supported as illustrated in. With code-domain sharing,two or more UEs are scheduled simultaneously by using different parts ofthe common code resource (different sets of physical channels).reasons, not able to dispread the full set of codes, and efficient support of smallpayloads when the transmitted data does not require the full set of allocated HSDSCHcodes. In either of these cases, it is obviously a waste of resources to assignthe full code resource to a single terminal.
  30. 30. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 30 Dept. of ECE (2013-2014) In addition to being allocated a part of the overall code resource, a certain partof the total available cell power should also be used for HS-DSCH transmission. To maximize the utilization of the power resource in the base station, the remaining power after serving other, power- controlled channels, should preferably be used for HS-DSCH transmission as illustrated in Figure 9.4. In principle, this results in a (more or less) constant transmission power in a cell. Since the HS-DSCH is rate controlled as discussed below, the HS-DSCH data rate can be selected to match the radio conditions and the amount of power instantaneously available for HS- DSCH transmission. To obtain rapid allocation of the shared resources, and to obtain a small enduser delay, the TTI should be selected as small as possible. At the same time, a too small TTI would result in excessive overhead as control signaling is required for each transmission. For HSDPA, this trade-off resulted in the selection of a 2 ms TTI. Downlink control signaling is necessary for the operation of HS-DSCH in each TTI. Obviously, the identity of the UE(s) currently being scheduled must be signaled as well as the physical resource (the channelization codes) used for transmission to this UE. The UE also needs to be informed about the transport format used for the transmission as well as hybrid-ARQ- related information. The resource and transport-format information consists of the part of the code tree used for data transmission, the modulation scheme used, and the transport-block size. The downlink control signaling is carried on the High-Speed Shared ControlChannel (HS- SCCH), transmitted in parallel to the HS-DSCH using a separate channelization code. The HS- SCCH is a shared channel, received by all UEs for which an HS-DSCH is configured to find out whether the UE has been scheduled or not. Several HS-SCCHs can be configured in a cell, but as the HS-DSCH is shared mainly in the time domain and only the currently scheduled terminal needs to receive the HS-SCCH, there is typically only one or, if code-domain sharing is supported in the cell, a few HS-SCCHs configured in each cell. However, each HS-DSCH- capable terminal is required to be able to monitor up to four HS-SCCHs.Four HS-SCCH has been found to provide sufficient flexibility in the schedulingof multiple UEs; if the number was significantly smaller the scheduler would havebeen restricted in which UEs to schedule simultaneously in case of code-domainsharing. HSDPA transmission also requires uplink control signaling as the hybrid- ARQmechanism must be able to inform the NodeB whether the downlink transmissionwas
  31. 31. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 31 Dept. of ECE (2013-2014) successfully received or not. For each downlink TTI in which the UE hasbeen scheduled, an ACK or NAK will be sent on the uplink to indicate the resultof the HS-DSCH decoding. This information is carried on the uplink High-Speed Dedicated Physical Control Channel (HS-DPCCH). One HS-DPCCH is set up for each UE with an HS DSCH configured. In addition, the NodeB needs informationabout the instantaneous downlink channel conditions at the UE for the purpose ofchannel-dependent scheduling and rate control. Therefore, each UE also measuresthe instantaneous downlink channel conditions and transmits a Channel-QualityIndicator (CQI), on the HS-DPCCH.In addition to HS-DSCH and HS-SCCH, an HSDPA terminal need to receivepower control commands for support of fast closed-loop power control of the uplink in the same way as any WCDMA terminal. This can be achieved by adownlink dedicated physical channel, DPCH, for each UE. In addition to powercontrol commands, this channel can also be used for user data not carried on theHS- DSCH, for example circuit-switched services. In Release 6, support for fractional DPCH, F-DPCH, is added to reduce theconsumption of downlink channelization codes. In principle, the only use fora dedicated channel in the downlink is to carry power control commands to theUE in order to adjust the uplink transmission. If all data transmissions, includinghigher-layer signaling radio bearers, are mapped to the HS-DSCH, it is a wasteof scarce code resources to use a dedicated channel with spreading factor 256 perUE for power control only. The F-DPCH resolves this by allowing multiple UEsto share a single downlink channelization code.To summarize, the overall channel structure with HSDPA is illustrated inneither the HS-PDSCH, nor the HS-SCCH, are subject to downlink macro diversityor soft handover. The basic reason is the location of the HS-DSCHscheduling in the NodeB. Hence, it is not possible to simultaneously transmitthe HS-DSCH to a single UE from multiple NodeBs, which prohibits the use ofinter-NodeB soft handover. Furthermore, it should be noted that within each cell. 4.3 Scheduler
  32. 32. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 32 Dept. of ECE (2013-2014) The scheduler for HSDPA is referred to as being fast due to the fact that, compared with Release 99 specifications; the scheduler is moved from RNC to node Bs to reduce delays so faster scheduling decisions can be made. In addition to other functionalities, such as the choice of redundancy version and modulation and coding scheme, a fundamental task of the scheduler for HSDPA is to schedule the transmission for users. The data to be transmitted to users are placed in different queues in a buffer and the scheduler needs to determine the sequential order in which the data streams are sent. The scheduling algorithms are: Round-robin method: This algorithm selects the user packets in a round robin fashion. In this method, the number of time slots allocated to each user can be chosen to be inversely proportional to the users‘ data rates, so the same number of bits is transmitted for every user in a cycle. Obviously, this method is the ―fairest‖ in the sense that the average delay and throughput would be the same for all users. However, there are two disadvantages associated with the round-robin method. The first is that it disregards the conditions of the radio channel for each user, so users in poor radio conditions may experience low data rates, whereas users in good channel conditions may not even receive any data until the channel conditions turn poor again. This is obviously against the spirit of the HSDPA and it would lead to the lowest system throughput. The second disadvantage of the round-robin scheduler is that there is no differentiation in the quality of services for different classes of users. Maximum C/I (carrier-to-interface) ratio method: In this method, the scheduler attempts to take advantage of the variations in the radio channel conditions for different users to the maximum, and always chooses to serve the user experiencing the best channel condition, that is, the one with maximum carrier-to-interference ratio. Apparently, the max C/I scheduler leads to the maximum system throughput but is the most unfair, as users in poor radio conditions may never get served or suffer from unacceptable delays. Proportional fairness or R[n]/Rav Method: This method takes into account both the short-term variation of the radio channel conditions and the long-term throughput of each user. In this method, the user with the largest R[n]/Rav is served first, where R[n] is the
  33. 33. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 33 Dept. of ECE (2013-2014) data rate in the current time slot n and Rav is the average data rate for the user in the past average window. The size of the average window determines the maximum duration that a user can be starved from data, and as such it reflects the compromise between the maximum tolerable delay and the cell throughput. According to this scheduling scheme, if a user is enjoying a very high average throughput, it‘s R[n]/Rav will probably not be the highest. Then it may give way to other users with poor average throughput and therefore high R[n]/Rav in the next time slots, so the average throughput of the latter can be improved. On the other hand, if the average throughput of a user is low, the R[n]/Rav could be high and it might be granted the right of transmission even if its current channel condition is not the best. The figure below illustrates the performance of different scheduling algorithm Fig. 4.4 performance of scheduling algorithms Fast scheduling and AMC, in conjunction with HARQ, is a way of maximizing the instantaneous use of the fading radio channel in order to realize maximum throughput. The HSDPA technology enables higher-rate data transmission through a higher-modulation and coding rate and limited retransmissions, while keeping the power allocated to HS-DSCH channel in a cell constant. Notwithstanding, the slow power control is still needed to adjust the power sharing among terminals and between different channel types.
  34. 34. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 34 Dept. of ECE (2013-2014) HSDPA Impact on Radio Access Network and UE Architecture All Release‘99 transport channels presented earlier in this document are terminated at the RNC. Hence, the retransmission procedure for the packet data is located in the serving RNC, which also handles the connection for the particular user to the core network. With the introduction of HS-DSCH, additional intelligence in the form of an HSDPA Medium Access Control (MAC) layer is installed in the Node B. This way, retransmissions can be controlled directly by the Node B, leading to faster retransmission and thus shorter delay with packet data operation when retransmissions are needed. With HSDPA, the Iub interface between Node B and RNC requires a flow control mechanism to ensure that Node B buffers are used properly and that there is no data loss due to Node B buffer overflow. Although there is a new MAC functionality added in the Node B, the RNC still retains the Release‘99/Release 4 functionalities of the Radio Link Control (RLC), such as taking care of the retransmission in case the HS-DSCH transmission from the Node N would fail after, for instance, exceeding the maximum number of physical layer retransmissions. The key functionality of the new Node B MAC functionality (MAC-hs) is to handle the Automatic Repeat Request (ARQ) functionality and scheduling as well as priority handling. Ciphering is done in any case in the RLC layer to ensure that the ciphering mask stays identical for each retransmission to enable physical layer combining of retransmissions. Similar to Node B a new MAC entity, MAC-hs is added in the UE architecture. The functionalityof the same as on the Node B side.
  35. 35. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 35 Dept. of ECE (2013-2014) Fig. 4.5 node b protocol stack Transport and Control Channel in HSDPA Fig. 4.6 transport and control channel in HSDPA
  36. 36. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 36 Dept. of ECE (2013-2014) High Speed Downlink Shared Channel (HS-DSCH) The HS-DSCH is allocated to users mainly on the basis of the transmission time interval (TTI), in which users are allocated within different TTIs. HS-DSCH has the following features: TTI = 2ms (3 time slots): This is to achieve short round trip delay for the operation between the terminal and the Node B for retransmissions. TTI in R99 is 10ms Adding higher order modulation scheme, 16 QAM, as well as lower encoding redundancy has increased the instantaneous peak data rate. In the code domain perspective, the SF is fixed; it is always 16, and multi-code transmission as well as code multiplexing of different users can take place. The maximum number of codes that can be allocated is 15, but depending on the terminal (UE) capability, individual terminals may receive a maximum of 5, 10 or 15 codes. 4.4 MOBILITY PROCEDURES Once a terminal is in the so-called CELL_DCH state when dedicated channels have been set up, it can be allocated with one or more HS-PDSCH(s), thus allowing it to receive data on the HS-DSCH. For dedicated channels, it is advantageous to employ the so-called soft handover technique, which is to transmit the same data from a number of Node Bs simultaneously to the terminal, as this provides diversity gain. Owing to the nature of packet transmission, however, synchronized transmission of the same packets from different cells is very difficult to achieve, so only hard handover is employed for HS-PDSCH. This is referred to HS-DSCH cell change, and the terminal can have only one serving HS- DSCH cell at a time. A serving HS-DSCH cell change message facilitates the transfer of the role of serving HS-DSCH radio link from one belonging to the source HS-DSCH cell to another
  37. 37. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 37 Dept. of ECE (2013-2014) belonging to the target HS-DSCH cell. In theory, the serving HS-DSCH cell change can be decided either by the mobile terminal or by the network. In UTRAN Release 5, however, only network-controlled serving HS-DSCH cell changes are supported and the decision can be based on UE measurement reports and other information available to the RNC. A network-controlled HS-DSCH cell change is performed based on the existing handover procedures in CELL_DCH state. Since the HSDPA radio channel is associated with dedicated physical channels in both the downlink and uplink, there are two possible scenarios in changing a serving HS-DSCH cell: (1) only changing the serving HS-DSCH cell and keeping the dedicated physical channel configuration and the active set for handover intact; or (2) changing the serving HS-DSCH cell in connection with an establishment, release, and/or reconfiguration of dedicated physical channels and the active set. Although an unsynchronized serving HS-DSCH cell change is permissible, a synchronized one is obviously preferable for ease of traffic management. In that case, the start and stop of the HS-DSCH transmission and reception are performed at a given time. This is convenient especially when an intranode B serving HS-DSCH cell change is performed, in which case both the source and target HS-DSCH cells are controlled by the same node B and the change happens between either frequencies or sectors. If an internode B serving HS-DSCH cell change is needed, the serving HS-DSCH Node B relocation procedure needs to be performed in the UTRAN. During the serving HS-DSCH node B relocation process, the HARQ entities located in the source HS-DSCH node B belonging to the specific mobile terminal are deleted and new HARQ entities in the target HS-DSCH node B are established. In this scenario, different controlling RNCs may control the source and target HS-DSCH node Bs, respectively.
  38. 38. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 38 Dept. of ECE (2013-2014) Intranode B Serving HS-DSCH Cell Change Figure below illustrates an intranode B serving HS-DSCH cell change while keeping the dedicated physical channel configuration and the active set, using the physical channel reconfiguration procedures. The transition from source to target HS-DSCH cells is performed in a synchronized fashion, that is, at a given activation time. For clarity, only the layers directly involved in the process are shown and the sequence of the events starts from the top and finishes at the bottom. Fig. 4.7 Intranode serving node b In this scenario, the terminal transmits a measurement report message containing intrafrequency measurement triggered by the event change of best cell. When the decision to perform handover is made at the serving RNC (SRNC), the node B is prepared for the serving HS-DSCH cell change at an activation time indicated by CPHY-RL-Commit-REQ primitive. The serving RNC then sends a physical channel reconfiguration message, which indicates the target HS-DSCH cell and the activation time to the UE. Since the same node B controls both the source and target HS-DSCH cells, it is not necessary to reset the MAC-hs entities. Once the
  39. 39. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 39 Dept. of ECE (2013-2014) terminal has completed the serving HS-DSCH cell change, it transmits a physical channel reconfiguration complete message to the network. It should be pointed out that, in this particular case, it is assumed that HS-DSCH transport channel and radio bearer parameters do not change. If transport channel or radio bearer parameters are changed, the serving HS-DSCH cell change would need to be executed by a transport channel reconfiguration procedure or a radio bearer reconfiguration procedure, respectively. Internode B Serving HS-DSCH Cell Change For terminals on the move, what happens more often than the intra-node B serving HS-DSCH cell change is the so-called internode B serving HS-DSCH cell change. For synchronized case, the reconfiguration is performed in two steps within UTRAN. To begin with, the terminal transmits a measurement report message containing measurement triggered by the event change of best cell. The serving RNC determines the need for hard handover based on received measurement report and/or load control algorithms. As the first step, the serving RNC establishes a new radio link in the target node B. After this, the target Node B starts transmission and reception on dedicated channels. In the second step, this newly created radio link is prepared for a synchronized reconfiguration to be executed at a given activation time indicated in the CPHY-RL-Commit-REQ primitive, at which the transmission of HS-DSCH will be started in the target HSDSCH node B and stopped in the source HS-DSCH node B. The serving RNC then sends a transport channel reconfiguration message on the old configuration. This message indicates the configuration after handover, both for DCH and HS- DSCH. The transport channel reconfiguration message includes a flag indicating that the MAC- hs entity in the terminal should be reset. The message also includes an update of transport channel-related parameters for the HS-DSCH in the target HS-DSCH cell. After physical synchronization is established, the terminal sends a transport channel reconfiguration complete message. The serving RNC then terminates reception and transmission
  40. 40. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 40 Dept. of ECE (2013-2014) on the old radio link for dedicated channels and releases all resources allocated to the UE. The process of internode B handover for HS-DSCH is shown in Figure below. Fig. 4.8 Intra Node B serving
  41. 41. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 41 Dept. of ECE (2013-2014) 5. KEY PERFORMANCE INDICATORS(KPI’S) 5.1 INTRODUCTION For radio network optimization it is necessary to have key performance indicators. These KPIs are parameters that are to be observed closely when the network monitoring process is going on. Mainly, the term KPI is used for parameters related to voice and data channels, but network performance can be broadly characterized into coverage, capacity and quality criteria also that cover the speech and data aspects. The performance of the radio network is measured in terms of KPIs related to voice quality, based on statistics generated from the radio network. Drive tests and network management systems are the best methods for generating these performance statistics. 5.2 NETWORK PERFORMANCE AND MONITORING The whole process of network performance monitoring consists of two steps: Monitoring the performance of the key parameters, Assessment of the performance of these parameters with respect to capacity and coverage. First the radio planners assimilate the information/parameters that they need to monitor. The KPIs are collected along with field measurements such as drive tests. For the field measurements, the tools used are ones that can analyze the traffic, capacity, and quality of the calls, and the network as a whole. For drive testing, a test mobile is used. This test mobile keeps on making calls in a moving vehicle that goes around in the various parts of the network. Based on the DCR, CSR, HO, etc., parameters, the quality of the network can then be analyzed. Apart from drive testing, the measurements can also be generated by the network management system and finally, when 'faulty' parameters have been identified and correct values are determined, the radio planner puts them in his network planning tool to analyze the change before these parameters are actually changed or implemented in the field.
  42. 42. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 42 Dept. of ECE (2013-2014) 5.3 DRIVE TESTING The quality of the network is ultimately determined by the satisfaction of the users of the network, the subscribers. Drive tests give the 'feel' of the designed network as it is experienced in the field. The testing process starts with selection of the 'live' region of the network where the tests need to be performed, and the drive testing path. Before starting the tests the engineer should have the appropriate kits that include mobile equipment (usually three mobiles), drive testing software (on a laptop), and a GPS (global positioning system) unit. When the drive testing starts, two mobiles are used to generate calls with a gap of few seconds (usually 15-20 s). The third mobile is usually used for testing the coverage. It makes one continuous call, and if this call drops it will attempt another call. The purpose of this testing to collect enough samples at a reasonable speed and in a reasonable time. If there are lots of dropped calls, the problem is analyzed to find a solution for it and to propose changes. 5.4 KPIs IN 3G The following are the key performance indicators in any 3G network. 1. Received Signal Code Power (RSCP) 2. Ec/Io 3. Handover status 4. Throughput 5. Eb/No
  43. 43. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 43 Dept. of ECE (2013-2014) RSCP Plot It is a coverage plot indicating the received code power for pilot channel. Ec/Io Plot This plot indicates the Ec/Io achieved on pilot channel. Handover status The plot indicates handover status for different areas in a given network. Throughput The plot indicates probable throughput in the network on WCDMA PS bearers. It should be noted that the throughput plot is based on the allotment of different PS bearers and does not indicate continuous user data transfer rate. Eb/No Plot In a mixed traffic scenario the plot indicates the Eb/No targets achieved for downlink.
  44. 44. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 44 Dept. of ECE (2013-2014) 6. Radio Network Optimization 6.1 Introduction to optimization Every alive Network needs to be under continues control to maintain/improve the performance. Optimization is basically the only way to keep track of the network by looking deep into statistics and collecting/analyzing drive test data. It is keeping an eye on its growth and modifying it for the future capacity enhancements. It also helps operation and maintenance for troubleshooting purposes. Successful Optimization requires: • Recognition and understanding of common reasons for call failure • Capture of RF and digital parameters of the call prior to drop • Analysis of call flow, checking messages on both forward and reverse links to establish ―what happened‖, where, and why. Optimization will be more effective and successful if you are aware of what you are doing. The point is that you should know where to start, what to do and how to do. Purpose and Scope of Optimization The optimization is to intend providing the best network quality using available spectrum as efficiently as possible. The scope will consist all below: • Finding and correcting any existing problems after site implementation and integration. • Meeting the network quality criteria agreed in the contract. • Optimization will be continuous and iterative process of improving overall network quality. • Optimization cannot reduce the performance of the rest of the network. • Area of interest is divided in smaller areas called clusters to make optimization and follow up processes easier to handle. 6.2 Optimization Process 6.2.1Problem Analysis Analyzing performance retrieve tool reports and statistics for the worst performing BSCs and/or Sites Viewing ARQ Reports for BSC/Site performance trends
  45. 45. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 45 Dept. of ECE (2013-2014) Examining Planning tool Coverage predictions Analyzing previous drive test data Discussions with local engineers to prioritize problems Checking Customer Complaints reported to local engineers 6.2.2 Checks Prior to Action Cluster definitions by investigating BSC borders, main cities, freeways, Major roads. Investigating customer distribution, customer habits (voice/data usage) Running specific traces on Network to categorize problems Checking trouble ticket history for previous problems Checking any fault reports to limit possible hardware problems prior to test. 6.2.3Drive Testing Preparing Action Plan Defining drive test routes Collecting RSSI Log files Scanning frequency spectrum for possible interference sources Re–driving questionable data 6.2.4Subjects to Investigate Non–working sites/sectors or TRXs In–active Radio network features like frequency hopping Disabled GPRS Overshooting sites – coverage overlaps Coverage holes C/I, C/A analysis High Interference Spots Drop Calls Capacity Problems Other Interference Sources Missing Neighbors One–way neighbors
  46. 46. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 46 Dept. of ECE (2013-2014) Ping–Pong Handovers Not happening handovers Accessibility and Retain ability of the Network Equipment Performance 6.2.5After the Test Post processing of data Plotting RX Level and Quality Information for overall picture of the driven area Initial Discussions on drive test with Local engineers Reporting urgent problems for immediate action Analyzing Network feature performance after new implementations Transferring comments on parameter implementations after new changes
  47. 47. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 47 Dept. of ECE (2013-2014) 7. DRIVE TESTING 7.1 Introduction The Indian telecommunication industry, with about 708.4 million mobile phone connections as of Jan 2013, is the second largest telecommunication network in the world. The Indian telecom industry is the fastest growing one in the world and it is projected that India will have a 'billion plus' mobile users by 2014. The Indian telephone lines have increased from a meagre 40 million (approx.) in the year 2000 to an astounding figure now. The main drivers for this extraordinary growth are because of Government‘s Telecom reforms and the stupendous success of GSM standard, which is the most popular standard for mobile telephony systems in the world. RF performance parameters such as the Received Signal Code Power, Ec/Io, Eb/No, throughput etc., are defined for the efficient and effective functioning of the RF network. The Drive Testing (DT) is performed in 3G UMTS network to ensure the availability, integrity, & reliability of the network. How to optimize the BTS coverage area successfully is the real challenge. As we move further ahead, the need for better technologies and reliability of services, integration and cost effective solutions have become a necessity for service providers. If the optimization is successfully performed, then the QOS, reliability and availability of RF Coverage area will be highly improved resulting in more customers and more profits to the mobile telecom service providers.
  48. 48. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 48 Dept. of ECE (2013-2014) Figure 7.1 Integrated drive-test bench 7.2 What is drive test? Drive testing is the most common and maybe the best way to analyze network performance by means of coverage evaluation, system availability, network capacity, and network, retain ability and call quality. Although it gives idea only on downlink side of the process, it provides huge perspective to the service provider about what is happening with a subscriber point of view. The drive testing is basically collecting measurement data with a phone, but the main concern is the analysis and evaluation part that is done after completion of the test. Remember that you are always asked to perform a drive test for not only showing the problems, but also explaining them and providing useful recommendations to correct them. Drive Test, as already mentioned, is the procedure to perform a test while driving. The vehicle does not really matter; you can do a drive test using a four-wheeler or a motorcycle or a bicycle. What matters is the hardware and software used in the test. • A notebook - or other similar device (1) • With collecting Software installed (2), • A Security Key - Dongle - common to these types of software (3), • At least one Mobile Phone (4), • One GPS (5),
  49. 49. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 49 Dept. of ECE (2013-2014) • A Scanner – optional (6). Also there is a common use of adapters and / or hubs that allow the correct interconnection of all equipment. The following is a schematic of the standard connections. Fig.7.2 Schematic diagram of drive test. The main goal is to collect test data, but they can be viewed / analyzed in real time (Live) during the test, allowing a view of network performance on the field. Data from all units are grouped by collection software and stored in one or more output files (1). Fig.7.3 Drive test output from various sources.
  50. 50. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 50 Dept. of ECE (2013-2014) • GPS: collecting the data of latitude and longitude of each point / measurement data, time, speed, etc. It is also useful as a guide for following the correct routes. • MS: mobile data collection, such as signal strength, best server, etc ... • SCANNER: collecting data throughout the network, since the mobile radio is a limited and does not handle all the necessary data for a more complete analysis. The minimum required to conduct a drive test, simplifying, is a mobile device with software to collect data and a GPS. Currently, there are already cell phones that do everything. They have a GPS, as well as a collection of specific software. They are very practical, but are still quite expensive. 7.3 Drive Test Routes Drive Test routes are the first step to be set, and indicate where testing will occur. This area is defined based on several factors, mainly related to the purpose of the test. The routes are predefined in the office. A program of a lot of help in this area is Google Earth. A good practice is to trace the route on the same using the easy paths or polygons. The final image can then be brought to the driver. Figure 7.4 Drive test route map
  51. 51. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 51 Dept. of ECE (2013-2014) Some software allows the image to be loaded as the software background (geo- referenced). This makes it much easier to direct routes to be followed. It is advisable to check traffic conditions by tracing out the exact pathways through which the driver must pass. It is clear that the movement of vehicles is always subject to unforeseen events, such as congestion, interdicted roads, etc. Therefore, one should always have on hand - know - alternate routes to be taken on these occasions. Avoid running the same roads multiple times during a Drive Test (use the Pause if needed). A route with several passages in the same way is more difficult to interpret. 7.4 Drive Test Schedule Again depending on the purpose, the test can be performed at different times - day or night. A Drive Test during the day shows the actual condition of the network - especially in relation to loading aspect of it. Moreover, a drive test conducted at night allows you to make, for example, tests on transmitters without affecting most users. Typically takes place nightly Drive Test in activities such System Design, for example with the integration of new sites. And Daytime Drive Test applies to Performance Analysis and also Maintenance. Important: regardless of the time, always check with the responsible area which sites are with alarms or even out of service. Otherwise, your job may be in vain. 7.5 Types of Calls The Drive Test is performed according to the need, and the types of test calls are the same that the network supports - calls can be voice, data, video, etc.. Everything depends on the technology (GSM, CDMA, UMTS, etc. ...), and the purpose of the test, as always. A typical Drive Test uses two phones. A mobile performing call (CALL) for a specific number from time to time, configured in the Collecting Software. And the other, in free or IDLE mode, i.e. connected, but not on call. With this, we collect specific data in IDLE and CALL modes for the network.
  52. 52. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 52 Dept. of ECE (2013-2014) The calls test (CALL) can be of two types: long or short duration. • Short calls should last the average of a user call - a good reference value is 180 seconds. Serve to check whether the calls are being established and successfully completed (being a good way to also check the network setup time). • Long calls serve to verify if the handovers (continuity between the cells) of the network are working, i.e. calls must not drop. 7.6 Types of Drive Test The main types of Drive Test are: • Performance Analysis • Integration of New Sites and change parameters of Existing Sites • Marketing • Benchmarking Tests for Analysis Performance is the most common, and usually made into clusters (grouping of cells), i.e., an area with some sites of interest. They can also be performed in specific situations, as to answer a customer complaint. In integration testing of new sites, it is recommended to perform two tests: one with the site without handover permission - not being able to handover to another site thus obtaining a total visualization of the coverage area. The other, later, with normal handover, which is the final state of the site. Depending on the type of alteration of the site (if any change in EIRP) both tests are also recommended. Otherwise, just perform the normal test. Marketing tests are usually requested by the marketing area of the company, for example showing the coverage along a highway, or at a specific region/location.
  53. 53. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 53 Dept. of ECE (2013-2014) Benchmarking tests aims to compare the competing networks. If the result is better, can be used as an argument for new sales. If worse, it shows the points where the network should be improved.
  54. 54. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 54 Dept. of ECE (2013-2014) 8.DRIVE TEST TOOL: JDSU E6474A v16.3 Agilent technologies have introduced the industry‘s first integrated test solution that in a single protocol analysis tool, seamlessly combines mobile device data captured from a RF interface and from a mobile terrestrial network. Troubleshooting and optimizing today‘s networks requires a broad understanding of the network performance over multiple interfaces. Rapid growth in the number of subscribers and in-data network usage has challenged the radio access network in both RF capacity and data throughput performance measuring across the last hop from the base station to the mobile device is essential for troubleshooting and optimization and without visibility to the air interface, network operators must manually correlate data from independent drive test and protocol analysis tools. Agilent‘s E6474A drive test tool has revolutionized and simplified end to end troubleshooting. The software allows users to correlate signaling procedures from the air interface and radio access network interfaces in a single view to detect and troubleshoot problems from the mobile phone to the network. The benefits of using this drive test tool are: • Automatic correlation of data collected from both the radio and network interfaces to find end-to-end performance issues more easily. • Mobile device and network combined protocol decoding as well as call trace groupings to enable a complete understanding of mobile access network behaviors. • Detection of lost and delayed messages from the air interface. • Isolation of base station with RF performance, capacity and interference problems to perform root cause analysis. • Evaluation of overall RF performance. 8.1 Drive Test Pre Requirements Before starting the drive test, the following data is to be collected from the BTS: • Height of Antenna
  55. 55. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 55 Dept. of ECE (2013-2014) • Antenna Azimuth – Orientation • Antenna tilt • Checking of RF Sectorization • Verification of serving area by existing Antenna orientations • VSWR & TX Power of DRX 8.2 Drive Test Procedure After collecting the required information from the BTS, the drive test is started. The equipment is set up in a vehicle and long calls as well as short calls are generated. A long call is a call which is generated as well as terminated by the user himself. A short call is a preprogrammed call generated by the system for a very small duration, say 10 seconds or more. A long call is used to measure the handover success rate as well as the Rx quality, while CSR and Rx level are measured on a short call. The drive test is done over a distance of 3 km or more from the starting point. Various parameters are observed and recorded during the drive test. The drive test procedure is as follows: • Tool may be setup for two mobiles – One for Long call and another for short calls (2 minutes). • In the route map following are to be enabled for Analysis. • Rx Level • RX Quality • Survey Markers (like H/O, DCR & H/O symbols) • Cell site Database. • Call statistics for the Calls in the Point -1 to be enabled.
  56. 56. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 56 Dept. of ECE (2013-2014) • Conduct the Drive Test – covering all sectors by observing the following Parameters: • RSCP(Received Signal Code Power) • Ec/Io • Eb/No • Handovers & Drop Calls • Throughput • Observe whether the nearest sector is serving or not. The data, as per the requirements are observed and recorded. The data is analyzed for performance. 8.3 Configuring the Drive Test Tool 8.3.1 Hardware Configuration The Hardware window shows the hardware devices which are to be added to the drive test tool. • One mobile for short call configuration • One mobile for Long call configuration • GPS File Project Manager New Project Name View Systempanels Hard ware window (right click) AddDevice Phone (short call) View Systempanels Hard ware window (right click) AddDevice Phone (Long call) View Systempanels Hard ware window (right click)Add Devices
  57. 57. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 57 Dept. of ECE (2013-2014) Fig. 8.1 Configuration of Hard ware Devices. 8.3.2 Configuring the Calls In Sequencer window we specify the type of test to be done by the each device i.e. mobiles For Short Call: ViewSystem panelSequencer (right click)Service model (right click)Parallel sequenceShort call For Long Call: ViewSystem panelSequencer (right click)Service model (right click)Parallel sequenceLong call
  58. 58. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 58 Dept. of ECE (2013-2014) Fig 8.2 Configurations of Calls 8.3.3 Configuring Short Call Properties Short CallCALL_CONTROL_TESTViewProperties • Number of times to run: Infinite -The number of times for a call to run throughout the Drive Test if after a disruption. • Inter Call Idle time: 5 sec -Time duration between the calls • Auto Dial: Yes -Makes the call automatically after 5 sec (Inter Call Idle time) • Call Statistics: Yes -Display of No. of Dropped calls, Good calls etc., (Call Analysis) • Immediate Dial: Yes -To dial immediately after disconnection.
  59. 59. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 59 Dept. of ECE (2013-2014) • Continuous Call: No -Since the Short Call would be terminated and re-initiated throughout the Drive Test, it is configured as No • Call Duration: 40 sec -Duration of the Short Call should be minimum to make a trail for every sector or cell • Call Setup: 20 sec -Time given to setup or answer a call, if it exceeds call will be terminated. • Call number: Any number -Destination or called party number • Auto Answer: No -If it is Yes, then the mobile would be only in incoming mode (doesn‘t suit for Drive Test) • COM Port: COM 58 -Number of port that to be connected to PC • Voice MOS Test: No -It is the Voice Mean Opinion score Test, not required for the Drive Test because person doing the Drive Test don‘t speak throughout the Test.
  60. 60. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 60 Dept. of ECE (2013-2014) Fig 8.3 Configurations of Short Call Properties 8.3.4 Configuring Long Calls Properties Long CallCALL_CONTROL_TESTViewProperties • Number of times to run: Infinite -The number of times for a call to run throughout the Drive Test if after a disruption. • Inter Call Idle time: 5 sec -Time duration between the calls • Auto Dial: Yes -Makes the call automatically after 5 sec (Inter Call Idle time) • Call Statistics: Yes -Display of No. of Dropped calls, Good calls etc., (Call Analysis) • Immediate Dial: Yes -To dial immediately after disconnection. • Continuous Call: Yes
  61. 61. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 61 Dept. of ECE (2013-2014) -Since the Long Call would be operated throughout the Drive Test, it is configured as Yes • Call Duration: NILL -As the Long Call is operated throughout the Drive Test the Call duration need not be specified. • Call Setup: 20 sec -Time given to setup or answer a call, if it exceeds call will be terminated. • Call number: Any number -Destination or called party number • Auto Answer: No -If it is Yes, then the mobile would be only in incoming mode (doesn‘t suit for Drive Test) • COM Port: COM 57 -Number of port that to be connected to PC • Voice MOS Test: No -It is the Voice Mean Opinion score Test, not required for the Drive Test because person doing the Drive Test don‘t speak throughout the Test.
  62. 62. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 62 Dept. of ECE (2013-2014) Fig 8.4 Configurations of Long Call Properties 8.3.5 Configuring of Map and Cell site Data MAP: ViewCommon ViewsMapOpen map file (Load from Destination address in PC) Cell site Data: ToolsOptionsCell siteOpen cell site data file (Load from Destination address in PC) Hyderabad map like streets, state highways, water bodies, national highways etc with cell sites given below • Cell sites near Gachibowli are shown below
  63. 63. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 63 Dept. of ECE (2013-2014) Fig. 8.5 Cell Sites of Gachibowli 8.3.6 Configuring the Data Items Configuring the Data Items Selection of parameters like Rx level, Rx Quality, CI ratio of both Short call and Long call which we want to display in the map through different colors and different ranges which are available in Data items window. For Short Call: ViewSystem PanelData itemsShort CallTraceGSM signal -Rx Level -Rx Quality For Long Call: ViewSystem PanelData itemsLong CallTraceGSM signal -Rx Level -Rx Quality -Ec/Io
  64. 64. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 64 Dept. of ECE (2013-2014) Fig. 8.6 Configurations of Data Items 8.3.7 Map Legend Map Legend shows the display of Configured Data Items Selected like Rx level, Rx Quality, CI ratio of both Short call and Long call in the map through different colors and different ranges as shown in the Legend Window in the below figure.
  65. 65. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 65 Dept. of ECE (2013-2014) Fig 8.7 Map Legends in the Drive Test.
  66. 66. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 66 Dept. of ECE (2013-2014) 9. DATA COLLECTION IN DRIVE TEST 9.1 Observations and Recordings Drive testing is the most common and maybe the best way to analyze Network performance by means of coverage evaluation, system availability, network capacity, network retain ability and call quality. Although it gives idea only on downlink side of the process, it provides huge perspective to the service provider about what‘s happening with a subscriber point of view. The data, as per the requirements are observed and recorded. The data is analyzed for performance. The following shots have been taken while conducting the drive test. • Drive test is nothing but collection of samples. Fig. 9.1 Collection of samples of the Drive Test. • GPS location or Vehicle position on the map is indicated with red pointer as shown below. Parameters like RSCP, Throughput and Ec/Io ratio of a call shown are below on the map.
  67. 67. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 67 Dept. of ECE (2013-2014) Fig 9.2 Measure of parameters in the Drive Test. Fig. 9.3 Drive Test from RTTC Gachibowli to Nanakramguda. • BSNL user events like blocked call, good call etc. are shown below.
  68. 68. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 68 Dept. of ECE (2013-2014) Fig. 9.4 Blocked call and good call view • BSNL long and short call views are given below. Fig 9.5(a) BSNL Long Call View in Drive Test.
  69. 69. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 69 Dept. of ECE (2013-2014) Fig. 9.5(b) BSNL Short Call View in Drive Test. BSNL drive test workspace view is shown below Fig 9.6 BSNL Drive Test signal
  70. 70. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 70 Dept. of ECE (2013-2014) 9.2 Drive Test Analysis 9.2.1 Bench Marks of TRAI Every leading network service provider in the market should follow the Benchmarks by the “TELECOM REGULATORY AUTHORITY OF INDIA”. A network is said to be good if it satisfies the benchmarks of TRAI. Downlink Parameters: • RSCP -85 to -95 dBm • Ec/Io -3 to -8 dBm • Handover success rate > 98% • Call setup success rate > 98% • Drop call rate < 3% (4) Call Analysis: (i) Call Setup Success Rate: Rate of calls which are successfully established. CSSR= No. of calls successfully setup * 100 Total no. of calls attempted (ii) Drop Call Rate: DCR= No. of Dropped calls * 100 Total no. of calls Established
  71. 71. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 71 Dept. of ECE (2013-2014) Table 6.1 Call Analysis of BSNL S.no Parameter BSNL 1 No of Call attempts 23 2 Successfully Established 22 3 No. of Blocked calls 1 4 No. of Dropped Calls 0 (a) BSNL: (i) CSSR = 22 * 100 = 95.65% 23 (iii) DCR = 1 * 100 = 4.35% 23
  72. 72. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 72 Dept. of ECE (2013-2014) 9.2.2 Comparison of Drive Test Parameters of BSNL S. No Details of parameter Gachibowli to Hitech City BSNL 1 RSCP Total No. of samples collected 8804 >65dBm 5541(62.93%) >75dBm 1366(15.51%) 2 Ec/Io Total No. of samples collected 8804 -8dBm to -3 dBm 7721 3 Handovers No. of H.O commands 39 No. of H.O Failures 1 No. of H.O completes 38 H.O Success Rate 97.43 4 Call analysis No. of Call attempts 23 Successfully Established 22 Success rate 96% No. of Blocked Calls 1 No. of Dropped Calls 0 Dropped Call Rate 0% 5 Throughput(Kbits/sec) 1402 Table 9.2 comparison of Drive Test Parameters of BSNL
  73. 73. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 73 Dept. of ECE (2013-2014) ADVANTAGES In competitive benchmarking, handover success rate, coverage and quality comparison like KPI of network is performed with competitors. Handover success rate, coverage and quality comparison for two operators for a city, results are taken using driving test tool, JDSU. It is also useful to network operators to know the problem in the network and the helps them to rectify them. In customer‘s point of view, users get to know the best network operators.
  74. 74. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 74 Dept. of ECE (2013-2014) 10. POST PROCESSING 10.1 INTRODUCTION TO ACTIX Actix analyzer is a software application running on Microsoft Windows that provides a series of analysis tools for post processing cellular network data. The tool is designed to address the applications such as: • Network performance and optimization • Feature testing • Service validation • Problem diagnosis and analysis • Network Benchmarking A post-processing tool for GSM, GPRS, UMTS, CDMA-one, CDMA2000 andIS-95. Actix provides users the ability to manage, visualize, replay, analyze and optimize networks based on collected data. A-RVS(RolloutVerificationSolution) Module will be used totroubleshoot and optimize UMTS networks. ACTIX, as a network optimization platform, is a powerful tool that will allow you to discover, locate, manage, troubleshoot and find solutions to network problem.
  75. 75. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 75 Dept. of ECE (2013-2014) SIGNAL LEVEL Fig 10.1 Signal level for short call Signalquality Fig 10.2 signal quality
  76. 76. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 76 Dept. of ECE (2013-2014) Handover During the call Fig 10.3 handovers during call Ec/No Value comparison
  77. 77. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 77 Dept. of ECE (2013-2014) Fig 10.4 EC/NO HSDPA CQI PARAMETER Fig 10.5 CQI
  78. 78. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 78 Dept. of ECE (2013-2014) HSDPA CQI DISTRIBUTION Fig 10.5 CQI distribution
  79. 79. 3G UMTS HSPA RADIO NETWORK OPTIMIZAION 79 Dept. of ECE (2013-2014) 11. CONCLUSION & FUTURE SCOPE The overall objectives of any RF design depend on number of factors that are determined by needs of customer. Through radio network optimization the service quality and resources usage of the network are greatly improved and the balance among coverage capacity and quality is achieved and been performed in BSNL service area.

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