Wireless Business SDE to AGM (LICE) PDF

INDEX Ch no. 1 2 3 4 5 6 Chapter Name Topic Covered BASICS OF MOBILE COMMUNICATION CELLULAR CONCEPT (CELL CONCEPT, SITE, SECTOR AND CLUSTER) FUNDAMENTALS OF GSM (FREQUENCY BAND, GSM SPECIFICATION) BACKHAUL MEDIA FOR BACKHAUL MEDIA FOR MOBILE RADIO MOBILE RADIO NETWORK NETWORK (OFC/ OFC SYSTEMS/ MINI LINK) AND RRH KPI REPORTS FOR KPIs OF 2G/3G/4G & 5 G 2G/3G/4G 3G MOBILE NETWORK UMTS (3G) HSPA, HSPA+ HSPA AND HSPA+ 3G RADIO NETWORK PLANNING AND OPTIMIZATION OF OPTIMISATION 2G/3G/4G & 5G RADIO NETWORK 7 4G MOBILE CORE and ACCESS N/W PLANING 8 MOBILE TRAFFIC REPORT 9 CNMS PORTAL AND MOBILE NOC MOBILE ANTENNA SYSTEM CNMC PORTAL OVERVIEW, MOBILE NOC Introduction to 5 G and VoNR INTRODUCT ION TO 5G VOICE OVER NEW RADIO (VoNR) 10 11 OVERVIEW OF 4G LTE 4G RADIO ACCESS NETWORK PCI PLANNING LTE ARCHITECTURE AND LTE CALL FLOW LTE AIR INTERFACE IMS AND VOICE OVER LTE(VoLTE) TRAFFIC REPORT ANALYSIS MOBILE ANTENNA SYSTEM (ANTENNA BASICS, AZIMUTH, TILT, VSWR) 1 BASICS OF MOBILE COMMUNICATION OBJECTIVES On completion of this chapter trainee will be able to understand Basic of Mobile communication. Topics covered will be: Cellular Concept Fundamentals of GSM GSM Specifications GSM Architecture CELLULAR CONCEPT Traditional mobile service was structured similar to television broadcasting. One very powerful transmitter located at the highest spot in an area would broadcast in a radius of up to fifty kilometers. The Cellular 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. In a cellular system, the covering area of an operator is divided into cells. A cell corresponds to the covering area of one transmitter or a small collection of transmitters. The cellular concept employs variable low power levels, which allows cells to be sized according to subscriber density and demand of a given area. As the population grows, cells can be added to accommodate that growth. Frequencies used in a cell will be reused several cells away. The distance between the cells using the same frequency must be sufficient to avoid interference. The frequency reuse will increase considerably the capacity in number of users. CELL SYSTEM 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 as shown in Figure. Each cell size varies depending upon landscape. Because of constraint imposed by natural terrain and man-made structures, the true shape of cell is not a perfect hexagon. In order to work properly, a cellular system must verify the following two main conditions: The power level of a transmitter within a single cell must be limited in order to reduce the interference with the transmitters of neighboring cells. Neighboring cells can not share the same channels. In order to reduce the interference, the frequencies must be reused only within a certain pattern. Figure 1: Cell System CLUSTER The spectrum allocated for a cellular network is limited. As a result there is a limit to the number of frequencies or channels that can be used. The cells are grouped into clusters. Group of cells in which no frequencies are reused is termed as a cluster. Figure 2: CLUSTER TYPES OF CELLS The density of population in a country is so varied that different types of cells are used: A. MACRO CELLS The macro cells are large cells for remote and sparsely populated areas. B. MICRO CELLS These cells are used for densely populated areas. By splitting the existing areas into smaller cells, the number of channels available is increased as well as the capacity of the cells. The power level of the transmitters used in these cells is then decreased, reducing the possibility of interference between neighboring cells. C. PICO CELLS Pico cells are small cells whose diameter is only few dozen meters; they are used mainly in indoor applications. It can cover e.g. a floor of a building or an entire building like shopping centers, Airports etc. D. SELECTIVE CELLS It is not always useful to define a cell with a full coverage of 360 degrees. In some cases, cells with a particular shape and coverage are needed. These cells are called selective cells. Typical examples of selective cells are the cells that may be located at the entrances of tunnels where coverage of 360 degrees is not needed. In this case, a selective cell with coverage of 120 degrees is used. E. UMBRELLA CELLS A freeway crossing very small cells produces an important number of handovers among the different small neighboring cells in case of a fast moving mobile subscriber. In order to solve this problem, the concept of umbrella cells is introduced. An umbrella cell covers several micro cells. The power level inside an umbrella cell is increased comparing to the power levels used in the micro cells that form the umbrella cell. When the speed of the mobile is too high, the mobile is handed over to the umbrella cell. The mobile will then stay longer in the same cell (in this case the umbrella cell). This will reduce the number of handovers and the work of the network. CELL SECTORING One way of reducing the level of interference is to use directional antenna at base stations, with each antenna illuminating a sector of the cell, and with a separate channel set allocated to each sector. There are two commonly used methods of Sectorisation either using 120˚ sector or 60˚ sector, both of which reduce the number of prime interference sources. The three sector case is generally used with a seven cell pattern, giving an overall requirement for 21 channel sets. FEATURES OF DIGITAL CELLULAR SYSTEM: A. SMALL CELLS: A cellular system uses many base stations with relatively small coverage radii (on the order of a 100 m to 30 km). B. FREQUENCY REUSEF: 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. For this reason each frequency is used simultaneously by multiple base-mobile pairs. This frequency reuse allows a much higher subscriber density per MHz of spectrum than other systems. C. SMALL, BATTERY-POWERED HANDSET: 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. D. 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. FUNDAMENTALS OF GSM A cellular mobile communications system uses a large number of low-power wireless transmitters to create cells the basic geographic service area of a wireless communications system. Variable power levels allow cells to be sized according to the subscriber density and demand within a particular region. As mobile users travel from cell to cell, their conversations are "handed over" between cells in order to maintain seamless service. Channels (frequencies) used in one cell can be reused in another cell some distance away. Cells can be added to accommodate growth, creating new cells in uncovered areas or overlaying cells in existing areas. The important objectives of the mobile communication are: Any time Anywhere communication Mobility & Roaming High capacity & subscriber density Efficient Use of Radio Spectrum Seamless Network Architecture Low Cost Innovative Services Standard Interface DIFFERENT GENERATIONS: TECHNOLOGY 1G 2G 2.5G 3G 4G First Design 1970 1980 1985 1990 2000 Implementation 1982 1991 1999 2002 2010? Analog Voice Digital Voice, SMS Package Data Standards AMPS TDMA, CDMA, GSM GPRS,EDG E Data Bandwidth 1.9 kbps 14.4 kbps 384 kbps Service Table 1. Figure 3: IP-oriented Broadband unlimited data up to multimedia 2 Mb/s data EVDO, WiMAX, W-CDMA, HSOPA HSDPA 2 mbps Different Generations Different Generations 200 mbps Figure 4: Basic Mobile Telephone Service Network DUPLEXING METHODOLOGY: Duplexing is the technique by which the send and receive paths are separated over the medium, since transmission entities (modulator, amplifiers, demodulators) are involved. There are two types of duplexing: A) Frequency Division Duplexing FDD B) Time Division Duplexing TDD A. Frequency Division Duplexing (FDD) Different Frequencies are used for send and receive paths and hence there will be a Forward band and reverse band. Duplexer is needed if simultaneous transmission (send) and reception (receive) methodology is adopted.Frequency separation between forward band and reverse band is constant. B. Time Division Duplexing (TDD) TDD uses different time slots for transmission and reception paths. Single radio frequency can be used in both the directions instead of two as in FDD. No duplexer is required. Only a fast switching synthesizer, RF filter path and fast antenna switch are needed. It increases the battery life of mobile phones. GSM use Frequency Division Duplexing. FREQUENCY BANDS AND CHANNEL ARRANGEMENT STANDARD OR PRIMARY GSM 900 BAND,P-GSM For Standard GSM 900 Band, the system is required to operate in the following frequency band: 890 - 915 Mhz: Mobile Transmit, Base Receive 935 - 960 Mhz: Base Transmit, Mobile Receive DCS 1800 Band: For DCS 1800 The system is required to operate in the following band: 1710 - 1785 MHz: Mobile Transmit, Base Receive 1805 - 1880 MHz: Base Transmit, Mobile Receive Uplink Frequency Downlink frequency Duplex Distance Carrier separation Frequency Channels Voice coder bit rate Modulation Air transmission Rate Access Method Speech Coder Duplexing Standard or Primary GSM 900 Band 890-915 MHz 935-960 MHz 45 MHz 200 KHz 124 13 Kbps GMSK 270.8333 Kbps FDMA/TDMA RPE-LTP FDD 1800 Band 1710 - 1785 MHz 1805 – 1880 MHz 95 MHz 200 KHz 374 13 Kbps GMSK 270.8333 Kbps FDMA/TDMA RPE-LTP FDD GSM NETWORK STRUCTURE Every telephone network needs a well-designed structure in order to route incoming called to the correct exchange and finally to the called subscriber. In a mobile network, this structure is of great importance because of the mobility of all its subscribers. In the GSM system, the network is divided into the following partitioned areas. GSM service area PLMN service area MSC service area Location area Cells. Figure 5: GSM- Network Structure GSM NETWORK SYSTEM GSM system basically designed as a combination of three major subsystems: Base Station Subsystem (BSS) Network Switching Subsystem (NSS) Operation Support Subsystem (OSS) GSM NETWORK ELEMENTS The major network elements are MS, Base Station Controller (BSC), Base Transceiver Station (BTS) and Mobile Service Switching Centre (MSC) and the four databases associated with MSC namely HLR, VLR, EIR and AUC. Figure 6: GSM- Architecture Mobile Station (MS) The MS includes radio equipment and the SIM (Subscriber Identity Module) that a subscriber needs in order to access the services provided by the GSM PLMN. The MS may include provisions for data communication as well as voice. A mobile transmits and receives messages to and from the GSM system over the air interface to establish and continue connections through the system. Each ME (Mobile Equipment) is identified by an International Mobile Equipment Identity (IMEI) that is permanently stored in the mobile unit. Upon request, the MS sends this number over the signalling channel to the MSC. The IMEI can be used to identify mobile units that are reported stolen or operating incorrectly.Just as the IMEI identities the mobile equipment, other numbers are used to identify the mobile subscriber.The Mobile Subscriber ISDN Number (MSISDN) is the number that the calling party dials in order to reach the subscriber. It is used by the land network to route calls toward an appropriate MSC. The international mobile subscriber identity (IMSI) is the primary identity of the subscriber within the mobile network and is permanently assigned to him. The GSM system can also assign a Temporary Mobile Subscriber Identity (TMSI) to identify a mobile. This number can be periodically changed by the system and protect the subscriber from being identified by those attempting to monitor the radio channel. These are five different categories of mobile telephone units specified by the European GSM system: 20W, 8W, 5W, 2W, and 0.8W. GSM subscribers are provided with a SIM card with its unique identification at the very beginning of the service. By divorcing the subscriber ID from the equipment ID, the subscriber may never own the GSM mobile equipment set. The subscriber is identified in the system when he inserts the SIM card in the mobile equipment. This provides an enormous amount of flexibility to the subscribers since they can now use any GSM-specified mobile equipment. Thus with a SIM card the idea of “Personalize” the equipment currently in use and the respective information used by the network (location information) needs to be updated. The smart card SIM is portable between Mobile Equipment (ME) units. The user only needs to take his smart card on a trip. He can then rent a ME unit at the destination, even in another country, and insert his own SIM. Any calls he makes will be charged to his home GSM account. Also, the GSM system will be able to reach him at the ME unit he is currently using. The SIM is a removable SC, the size of a credit card, and contains an integrated circuit chip with a microprocessor, random access memory (RAM), and read only memory (ROM). It is inserted in the MS unit by the subscriber when he or she wants to use the MS to make or receive a call. As stated, a SIM also comes in a modular form that can be mounted in the subscriber’s equipment. When a mobile subscriber wants to use the system, he or she mounts their SIM card and provide their Personal Identification Number (PIN), which is compared with a PIN stored within the SIM. If the user enters three incorrect PIN codes, the SIM is disabled. Base Transceiver Station (BTS) The BSS is a set of BS equipment (such as transceivers and controllers) that is in view by the MSC through a single A interface as being the entity responsible for communicating with MSs in a certain area. The radio equipment of a BSS may be composed of one or more cells. A BSS may consist of one or more BS. The interface between BSC and BTS is designed as an A-bis interface. The BSS includes two types of machines: the BTS in contact with the MSs through the radio interface and the BSC, the latter being in contact with the MSC. The function split is basically between transmission equipment, the BTS, and managing equipment at the BSC. A BTS compares radio transmission and reception devices, up to and including the antennas, and also all the signal processing specific to the radio interface. A single transceiver within BTS supports eight basic radio channels of the same TDM frame. A BSC is a network component in the PLMN that function for control of one or more BTS. It is a functional entity that handles common control functions within a BTS. A BTS is a network component that serves one cell and is controlled by a BSC. BTS is typically able to handle three to five radio carriers, carrying between 24 and 40 simultaneous communication. Reducing the BTS volume is important to keeping down the cost of the cell sites. An important component of the BSS that is considered in the GSM architecture as a part of the BTS is the Transcoder/Rate Adapter Unit (TRAU). The TRAU is the equipment in which coding and decoding is carried out as well as rate adoption in case of data. Although the specifications consider the TRAU as a subpart of the BTS, it can be sited away from the BTS (at MSC), and even between the BSC and the MSC. The interface between the MSC and the BSS is a standardized SS7 interface (Ainterface) that, as stated before, is fully defined in the GSM recommendations. This allows the system operator to purchase switching equipment from one supplier and radio equipment and the controller from another. The interface between the BSC and a remote BTS likewise is a standard the A-bis. In splitting the BSS functions between BTS and BSC, the main principle was that only such functions that had to reside close to the radio transmitters/receivers should be placed in BTS. This will also help reduce the complexity of the BTS. Base Station Controller (BSC) The BSC, as discussed, is connected to the MSC on one side and to the BTS on the other. The BSC performs the Radio Resource (RR) management for the cells under its control. It assigns and release frequencies and timeslots for all MSs in its own area. The BSC performs the inter-cell handover for MSs moving between BTS in its control. It also reallocates frequencies to the BTSs in its area to meet locally heavy demands during peak hours or on special events. The BSC controls the power transmission of both BSSs and MSs in its area. The minimum power level for a mobile unit is broadcast over the BCCH. The BSC provides the time and frequency synchronization reference signals broadcast by its BTS. The BSC also measures the time delay of received MS signals relative to the BTS clock. If the received MS signal is not centred in its assigned timeslot at the BTS, The BSC can direct the BTS to notify the MS to advance the timing such that proper synchronization takes place. The BSC may also perform traffic concentration to reduce the number of transmission lines from the BSC to its BTS. Mobile Switching Center (MSC) The network and the switching subsystem together include the main switching functions of GSM as well as the databases needed for subscriber data and mobility management (VLR). The main role of the MSC is to manage the communications between the GSM users and other telecommunication network users. The basic switching function performed by the MSC is to coordinate setting up calls to and from GSM users. The MSC has interface with the BSS on one side (through which MSC VLR is in contact with GSM users) and the external networks on the other (ISDN/PSTN/PSPDN). The main difference between a MSC and an Exchange in a fixed network is that the MSC has to take into account the impact of the allocation of RRs and the mobile nature of the subscribers and has to perform, in addition, at least, activities required for the location registration and handover. The MSC is a telephony switch that performs all the switching functions for MSs located in a geographical area as the MSC area. The MSC must also handle different types of numbers and identities related to the same MS and contained in different registers: IMSI, TMSI, ISDN number, and MSRN. In general identities are used in the interface between the MSC and the MS, while numbers are used in the fixed part of the network, such as, for routing. As stated, the main function of the MSC is to coordinate the set-up of calls between GSM mobile and PSTN users. Specifically, it performs functions such as paging, resource allocation, location registration, and encryption. Specifically, the call-handling function of paging is controlled by MSC. MSC coordinates the set-up of call to and from all GSM subscribers operating in its areas. The dynamics allocation of access resources is done in coordination with the BSS. More specifically, the MSC decides when and which types of channels should be assigned to which MS. The channel identity and related radio parameters are the responsibility of the BSS; The MSC provides the control of interworking with different networks. It is transparent for the subscriber authentication procedure. The MSC supervises the connection transfer between different BSSs for MSs, with an active call, moving from one call to another. This is ensured if the two BSSs are connected to the same MSC but also when they are not. In this latter case the procedure is more complex, since more than one MSC in involved. The MSC performs billing on calls for all subscribers based in its areas. When the subscriber is roaming elsewhere, the MSC obtains data for the call billing from the visited MSC. Encryption parameters transfers from VLR to BSS to facilitate ciphering on the radio interface are done by MSC. The exchange of signalling information on the various interface toward the other network elements and the management of the interface themselves are all controlled by the MSC. Finally, the MSC serves as a SMS gateway to forward SMS messages from Short Message Service Center (SMSC) to the subscribers and from the subscribers to the SMSCs. It thus acts as a message mailbox and delivery system. Visitor Location Register (VLR) The VLR is collocated with an MSC. A MS roaming in an MSC area is controlled by the VLR responsible for that area. When a MS appears in a LA, it starts a registration procedure. The MSC for that area notices this registration and transfers to the VLR the identity of the LA where the MS is situated. A VLR may be in charge of one or several MSC LA’s. The VLR constitutes the databases that support the MSC in the storage and retrieval of the data of subscribers present in its area. When an MS enters the MSC area borders, it signals its arrival to the MSC that stores its identity in the VLR. The information necessary to manage the MS is contained in the HLR and is transferred to the VLR so that they can be easily retrieved if so required. The data contained in the VLR and in the HLR are more or less the same. Nevertheless the data are present in the VLR only as long as the MS is registered in the area related to that VLR. Data associated with the movement of mobile are IMSI, MSISDN, MSRN, and TMSI. The terms permanent and temporary, in this case, are meaningful only during that time interval. Some data are mandatory, others are optional. Home Location Register (HLR) The HLR is a database that permanently stores data related to a given set of subscribers. The HLR is the reference database for subscriber parameters. Various identification numbers and addresses as well as authentication parameters, services subscribed, and special routing information are stored. Current subscriber status including a subscriber’s temporary roaming number and associated VLR if the mobile is roaming, are maintained. The HLR provides data needed to route calls to all MS-SIMs home based in its MSC area, even when they are roaming out of area or in other GSM networks. The HLR provides the current location data needed to support searching for and paging the MSSIM for incoming calls, wherever the MS-SIM may be. The HLR is responsible for storage and provision of SIM authentication and encryption parameters needed by the MSC where the MS-SIM is operating. It obtains these parameters from the AUC. The HLR maintains a record of which supplementary service each user has subscribed to and provides permission control in granting services. The HLR stores the identification of SMS gateways that have messages for the subscriber under the SMS until they can be transmitted to the subscriber and receipt is knowledge. Some data are mandatory, other data are optional. Both the HLR and the VLR can be implemented in the same equipment in an MSC (collocated). A PLMN may contain one or several HLRs. Authentication Center (AUC) The AUC stores information that is necessary to protect communication through the air interface against intrusions, to which the mobile is vulnerable. The legitimacy of the subscriber is established through authentication and ciphering, which protects the user information against unwanted disclosure. Authentication information and ciphering keys are stored in a database within the AUC, which protects the user information against unwanted disclosure and access. In the authentication procedure, the key Ki is never transmitted to the mobile over the air path, only a random number is sent. In order to gain access to the system, the mobile must provide the correct Signed Response (SRES) in answer to a random number (RAND) generated by AUC. Also, Ki and the cipher key Kc are never transmitted across the air interface between the BTS and the MS. Only the random challenge and the calculated response are transmitted. Thus, the value of Ki and Kc are kept secure. The cipher key, on the other hand, is transmitted on the SS7 link between the home HLR/AUC and the visited MSC, which is a point of potential vulnerability. On the other hand, the random number and cipher key is supposed to change with each phone call, so finding them on one call will not benefit using them on the next call. The HLR is also responsible for the “authentication” of the subscriber each time he makes or receives a call. The AUC, which actually performs this function, is a separate GSM entity that will often be physically included with the HLR. Being separate, it will use separate processing equipment for the AUC database functions. Equipment Identity Register (EIR) EIR is a database that stores the IMEI numbers for all registered ME units. The IMEI uniquely identifies all registered ME. There is generally one EIR per PLMN. It interfaces to the various HLR in the PLMN. The EIR keeps track of all ME units in the PLMN. It maintains various lists of message. The database stores the ME identification and has nothing do with subscriber who is receiving or originating call. There are three classes of ME that are stored in the database, and each group has different characteristics. White List: contains those IMEIs that are known to have been assigned to valid MS’s. This is the category of genuine equipment. Black List: contains IMEIs of mobiles that have been reported stolen. Grey List: contains IMEIs of mobiles that have problems (for example, faulty software, wrong make of the equipment, etc.). This list contains all MEs with faults not important enough for barring. Interworking Function (IWF) GSM provides a wide range of data services to its subscribers. The GSM system interface with various public and private data networks. It is the job of the IWF to provide this interfacing capability. The IWF, which in essence is a part of MSC, provides the subscriber with access to data rate and protocol conversion facilities so that data can be transmitted between GSM Data Terminal Equipment (DTE) and a land-line DTE. Echo Canceller (EC) EC is used on the PSTN side of the MSC for all voice circuits. The EC is required at the MSC PSTN interface to reduce the effect of GSM delay when the mobile is connected to the PSTN circuit. The total round-trip delay introduced by the GSM system, which is the result of speech encoding, decoding and signal processing, is of the order of 180 ms. Normally this delay would not be an annoying factor to the mobile, except when communicating to PSTN as it requires a two-wire to four-wire hybrid transformer in the circuit. This hybrid is required at the local switching office because the standard local loop is a two-wire circuit. Due to the presence of this hybrid, some of the energy at its four-wire receive side from the mobile is coupled to the four-wire transmit side and thus retransmitted to the mobile. This causes the echo, which does not affect the land subscriber but is an annoying factor to the mobile. The standard EC cancels about 70 ms of delay. During a normal PSTN (land-to-land call), no echo is apparent because the delay is too short and the land user is unable to distinguish between the echo and the normal telephone “side tones” However, with the GSM round-trip delay added and without the EC, the effect would be irritating to the MS subscriber. Operation and Maintenance Center The OMC provides alarm-handling functions to report and log alarms generated by the other network entities. The maintenance personnel at the OMC can define that criticality of the alarm. Maintenance covers both technical and administrative actions to maintain and correct the system operation, or to restore normal operations after a breakdown, in the shortest possible time. The fault management functions of the OMC allow network devices to be manually or automatically removed from or restored to service. The status of network devices can be checked, and tests and diagnostics on various devices can be invoked. For example, diagnostics may be initiated remotely by the OMC. A mobile call trace facility can also be invoked. The performance management functions included collecting traffic statistics from the GSM network entities and archiving them in disk files or displaying them for analysis. Because a potential to collect large amounts of data exists, maintenance personal can select which of the detailed statistics to be collected based on personal interests and past experience. As a result of performance analysis, if necessary, an alarm can be set remotely. The OMC provides system change control for the software revisions and configuration data bases in the network entities or uploaded to the OMC. The OMC also keeps track of the different software versions running on different subsystems of the GSM. GSM IDENTITIES International Mobile Subscriber Identity (IMSI) An IMSI is assigned to each authorized GSM user. It consists of a mobile country code (MCC), mobile network code (MNC), and a PLMN unique mobile subscriber identification number (MSIN). The IMSI is not hardware-specific. Instead, it is maintained on a SC by an authorized subscriber and is the only absolute identity that a subscriber has within the GSM system. The IMSI consists of the MCC followed by the NMSI and shall not exceed 15 digits. Temporary Mobile Subscriber Identity (TMSI) A TMSI is a MSC-VLR specific alias that is designed to maintain user confidentiality. It is assigned only after successful subscriber authentication. The correlation of a TMSI to an IMSI only occurs during a mobile subscriber’s initial transaction with an MSC (for example, location updating). Under certain condition (such as traffic system disruption and malfunctioning of the system), the MSC can direct individual TMSIs to provide the MSC with their IMSI. Mobile Station ISDN Number (MSISDN) The MS international number must be dialled after the international prefix in order to obtain a mobile subscriber in another country. The MSISDN numbers is composed of the country code (CC) followed by the National Significant Number (NSN), which shall not exceed 15 digits. The Mobile Station Roaming Number (MSRN) The MSRN is allocated on temporary basis when the MS roams into another numbering area. The MSRN number is used by the HLR for rerouting calls to the MS. It is assigned upon demand by the HLR on a per-call basis. The MSRN for PSTN/ISDN routing shall have the same structure as international ISDN numbers in the area in which the MSRN is allocated. The HLR knows in what MSC/VLR service area the subscriber is located. At the reception of the MSRN, HLR sends it to the GMSC, which can now route the call to the MSC/VLR exchange where the called subscriber is currently registered. International Mobile Equipment Identity (IMEI) The IMEI is the unique identity of the equipment used by a subscriber by each PLMN and is used to determine authorized (white), unauthorized (black), and malfunctioning (gray) GSM hardware. In conjunction with the IMSI, it is used to ensure that only authorized users are granted access to the system. An IMEI is never sent in cipher mode by MS. CONCLUSION Mobile Communication will always useful as it has mobility , the newer antenna system MIMO will play very important role in modern day communication. 2 BACKHAUL MEDIA FOR MOBILE RADIO NETWORK (OFC/ OFC SYSTEMS/ MINI LINK) AND RRH LEARNING OBJECTIVE After completion of this chapter participant will able to understand about: Importance of backhaul media in 3G Various type of Backhaul media Choice of backhauling Concept of Cloud RAN INTRODUCTION The physical part of a communications network between the central backbone and the individual local networks is known as backhaul. Mobile backhaul refers to the transport network that connects the core network and the RAN (Radio Access Network) of the mobile network. Recently, the introduction of small cells has given rise to the concept of front haul, which is a transport network that connects the macro cell to the small cells. Whilst mobile backhaul and front haul are different concept, the term mobile backhaul is generally used to encompass both concepts. Figure 7: Backhaul Concept Cell phones communicating with a single cell tower constitute a local subnetwork; the connection between the cell tower and the rest of the world begins with a backhaul link to the core of the internet service provider's network (via a point of presence). A backhaul may include wired, fiber optic and wireless components. Wireless sections may include using microwave bands and mesh and edge network topologies that may use a high-capacity wireless channel to get packets to the microwave or fiber links. MOBILE BACKHAUL N/W Mobile backhaul is the transport network that connects the core network and the RAN/Cell Site. The connection between the cell tower and the rest of the world begins with a backhaul link to the core N/w. A backhaul may include wired, fiber optic and wireless components. Wireless sections may include using microwave bands and mesh and edge network topologies Interconnection b/n core network elements is done through backbone N/w. FRONT HAUL VS BACKHAUL Split RAN architecture has reshaped the traditional definitions of front haul and backhaul. In its earliest incarnation, backhaul was simply described as the connection between Cell Site to BSC/RNC (In 2G/3G) Front haul became a necessary addition when a new link connected centralized BBU to individual RRH. Front haul is connection in RAN infrastructure between the Baseband Unit (BBU) and Remote Radio Head (RRH). Front haul originated with LTE networks when operators first moved their radios closer to the antennas. This new link was established to supplement to the backhaul connection between the BBU and central network core. IMPORTANCE OF MOBILE BACKHAUL Wireless and fixed-line backhaul infrastructure is an essential component of the mobile telecommunications network. Mobile networks are ubiquitous and support a mix of voice, video, text and data traffic originating from and terminating to mobile devices. All of this traffic must be conveyed between the mobile cellular base stations and the core network. The 3G and 4G Long-Term Evolution (LTE) strive for more network capacity, latency reduction, and the need to deliver an enhanced user experience. In the era of 5G, where a network will be densified and more stringent requirement will be imposed, mobile backhaul will become even more important. MOBILE BACKBONE NETWORK Mobile backbone network refers to the interconnection of core elements situated at separate geographic locations. As the requirement of bandwidth is large, typically, OFC is used in the backbone network. However, MW is also sometimes used in the backbone network, particularly in those areas where laying fibre is not a feasible option due to difficult terrain, time constraints or economic viability. TECHNOLOGY CHOICES FOR MOBILE BACKHAUL The most common network type in which backhaul is implemented is a mobile network. A backhaul of a mobile network, also referred to as mobile-backhaul connects a cell site towards the core network. The two main methods of mobile backhaul implementations are fiber-based backhaul and wireless point-to-point backhaul. Other methods, such as copper-based wire line, satellite communications and point-tomultipoint wireless technologies are being phased out as capacity and latency requirements become higher in 4G and 5G networks. Figure 8: Mobile Backhaul Network Choices The technological solutions used for backhaul, including both wireline and wireless solutions are given below: COPPER-LINE Copper-based backhaul was the primary backhaul technology for 2G/3G. At the heart of copper-based backhaul is the T1/E1 protocol, which supported 1.5 Mbps to 2 Mbps. This bandwidth can be boosted by using DSL over the copper pair and DSL is still an option for mobile backhaul for indoor small cells, in-building and public venue small cell networks. FIBRE-OPTIC IN BACKHAUL MEDIA FOR MOBILE RADIO NETWORK (OFC/OFC SYSTEMS) This technology is the mainstay wired backhaul in MNO networks and second overall only to microwave backhaul. Even though fibre has significant inherent bandwidth carrying capability, several additional techniques can be used to offset any bandwidth constraints and essentially rendering the fibre assets future-proof. Figure 9: OFC Media and System Mobile Network Backhaul These techniques include Wavelength Division Multiplexing (WDM) technology which enables multiple optical signals to be conveyed in parallel by carrying each signal on a different wavelength or colour of light. WDM can be divided into Coarse WDM (CDWM) or Dense WDM (DWDM). CWDM provides 8 channels using 8 wavelengths, while DWDM uses close channel spacing to deliver even more throughput per fibre. Modern systems can handle up to 160 signals, each with a bandwidth of 10 Gbps for a total theoretical capacity of 1.6 Tbps per fibre. The traffic generated by LTE has accelerated the demand for Fiber to the Tower (FTTT) and has required Mobile Network Operators (MNOs) to upgrade many aspects of their backhaul networks to fibre-based Carrier Ethernet. The main limitations of fibre are the cost and logistics of deploying fibre (ducts etc.). Also it can take several months to provision a cell site with fibre optic backhaul. Fibre optic will remain as the main choice for backhaul. WIRELESS BACKHAUL (MICROWAVE MINI-LINK) Despite fibre being the preferred choice for 3G/4G/5G backhaul, microwave backhaul is the most used technology due to a combination of its capability and relative ease of deployment (i.e. no need for trenches/ducting) making it a low-cost option that can be deployed in a matter of days. Microwave backhaul solutions in the 7 GHz to 40 GHz bands, in addition to higher microwave bands such as V-band (60 GHz) and the Eband (70/80 GHz) can be relied. Backhaul links using the V-band or the E-band are well suited to supporting 5G due to their 10 Gbps to 25 Gbps data throughput capabilities. Figure 10: Microwave Mini-Links for Mobile Communications Microwave can be used in LOS or NLOS mode which makes it ideal to be used in a chain, mesh or ring topologies to enable resilience and/or reach. LOS VS. NLOS LOS backhaul has the advantage of using a highly directed beam with little fading or multi-path dispersion and enables efficient use of spectrum as multiple transceivers can be located within a few feet of each other and use the same frequency to transmit different data streams. NLOS backhaul is much more “plug and play” and so take less time with less skilled labour to set up. NLOS backhaul OFDM technology (Orthogonal Frequency Division Multiplexing) to relay information back to a central base station. NLOS backhaul needs only to be within a range of the receiver unit with OFDM providing a level of tolerance to multi-path fading not possible with LOS SATELLITE BACKHAUL Satellite Backhaul is a niche solution and used in fringe areas (e.g. remote rural areas) and sometimes as an emergency/temporary measure (e.g. a disaster area. This backhaul is used in developing markets and as a complementary role in developed markets. The technology can deliver 150Mbps/10Mbps (downlink/.uplink). However, latency is a challenge as there a round trip delay of circa 500-600ms for a geostationary satellite. LEO (Low Earth Orbit) satellites have tried to address the latency issue (i.e. using a much lower orbit of 1500km versus 36000km and resulting in a one way trip of circa 50ms). However, LEO satellites are not geostationary and thus there is sometimes a need to route traffic via multiple satellites. FREE SPACE OPTICS (FSO) Free Space Optics (FSO) is a newer low-latency technology that offers speeds comparable to fibre optics that transmit voice, video and data with up to 1.5Gbps, and can be deployed as backhaul to expand mobile network footprint with building-to-building connectivity. The high bandwidth can be provided with a reception of light by deploying free space optics technology. BSNL is likely to use free space optics, a new line-of-sight outdoor wireless technology, to overcome backhaul constraints in large arid areas of Rajasthan and Gujarat plains. WIFI BACKHAUL There is marginal use of this technology for macrocell backhaul. The unlicensed nature of the technology combined with the growing interference from increasing public and private WLANs plus poor transmission ranges severely limits its deployment. CHALLENGES IN MOBILE BACKHAUL There are a number of market trends that result in new challenges and requirements that must be met by the backhaul. EVOLUTION OF LTE Technical innovations occurring on LTE, which is known as LTE-Advanced Pro or 4.5G which enable enhancements such as improved peak bandwidth and greater energy efficiency for IoT connections. The peak bandwidth of 4.5G is around 1Gbps which is 810x higher than standard LTE, and will enable (inter alia) support of video traffic at 4K resolution to mobile devices. EMERGENCE OF 5G The 5G network will comprise both NR (New Radio) as well as a new 5G Core Network (5GC). The advent of NR offers a leap in bandwidth speeds in comparison to 3G and 4G via the utilisation of higher frequency spectrum. The higher frequencies enable wider channel bandwidths at the access but also result in smaller cell sizes. Both have implications for backhaul. NETWORK SLICING In 5G Network, one concept of “network slicing” is introduced whereby the physical network infrastructure can be partitioned into bespoke logical networks (“slices”) in the RAN and 5G core which are targeted to the needs of a specific application or use case. Slicing will impact on the backhaul network. SUBSCRIBER GROWTH Backhaul strategy/evolution must cope with both an increase in subscriptions as well as a large number of those subscriptions being “high bandwidth” users. MOBILE DATA TRAFFIC GROWTH The increasing subscriber total plus increased access bandwidth usage of those subscribers results in mobile data traffic increasing at a rate. STRINGENT LATENCY REQUIREMENTS Both 5G mission-critical applications and increased video streaming will result in more stringent end-end latency requirements and impact on the backhaul latency budget. If higher latency backhaul links are deployed (e.g. satellite links), then such backhaul would only carry 2G/3G and non-latency sensitive LTE services. NETWORK DENSIFICATION: The increased demand for mobile broadband results in the number of macrocell. The new macrocells include both 4G and 5G technologies. This results in extra traffic to backhaul as well as additional challenges due to the smaller cell size for 5G NR. ALTERNATIVE ARCHITECTURES FOR MOBILE BACKHAUL OPTIMISATION MULTI ACCESS EDGE COMPUTING MEC (Multi-access edge computing) is where computing and intelligence capabilities that were mostly centralized in the core network are provided at the edge of the access network. MEC enables high bandwidth and ultra-low latency access to cloud computing/IT services at the edge to be accessed by applications developers and content providers. MEC, while incurring a cost to implement core functions at the edge, can provide opportunities to optimise backhaul demand via caching and/or local breakout. Caching reduces the load on mobile backhaul and enhances the customer experience by storing frequently accessed contents in the edge network. Customers can access the contents at a lower latency (with less distance for signal to travel) and backhaul demand is reduced as there is no need to reach further to the external network to obtain the contents. Local breakout also enables the mobile backhaul to be optimised as the contents do not need to travel to the core network and then to the internet. The caveat with local breakout is that the transport network to connect the edge to the internet needs to be in place and therefore won’t optimise cost in certain scenarios. CLOUD RAN Cloud RAN is where some layers of radio access network are centralized to an edge site rather than at the cell site, which allows some (or all) of the processing capabilities to be focused at the edge site reducing the complexities at the cell site. This architecture is suitable in the small cell era, where only a little space and cost constraint is affordable at the cell site. While the architecture may not be suitable for traditional macrocell base stations as they would need to process significant load of signal transmitted from/received by various radio elements, heterogeneous networks with many small cells would benefit from this architecture. As shown in the figure below, Cloud RAN in its two forms (low-level and highlevel splits) significantly reduces complexities and capabilities at the cell site to be concentrated in the edge site. The low-level split is where only the physical layer is processed at the edge site while all the electronics are concentrated in the edge site. This architecture allows easy installation and very low complexity at the cell site but comes at a higher fronthaul cost as baseband signals would need to be transferred. On the other hand, high-level split brings relatively less fronthaul cost but comes with more complexity at the cell site than low-level split. Figure 11: Cloud RAN Architecture RRH A remote radio head (RRH), also called a remote radio unit (RRU) in wireless networks, is a remote radio transceiver that connects to radio base station unit via electrical or wireless interface. The RRH is termed “Remote” as it is usually installed on a mast-top, or tower-top location that is physically some distance away from the base station hardware which is often mounted in an indoor rack-mounted location. In wireless system technologies such as GSM, CDMA, UMTS, LTE this Radio equipment is remote to the BTS/NodeB/eNodeB, and is also called Remote Radio Head. This equipment will be used to extend the coverage of a BTS/NodeB/eNodeB like rural areas or tunnels. They are generally connected to the BTS/NodeB/eNodeB via a fibre optic cable using Common Public Radio Interface protocols. Figure 12: RRH Using Wireless (Microwave, Millimetre Wave, MMW, Free Space Optics, and FSO) links instead of fibre allows the Remote Radio Head (RRH) to be connected without need for fibre optics. By avoiding the needs for digging, trenches, leased circuits from telcos, dark fibre or way-leaves for disrupting busy city streets, 4G/LTE networks can be realised very quickly with installation taking hours rather than days, weeks or months. Figure 13: Backhaul for RRH IMPORTANCE OF RRH RRHs have become one of the most important subsystems of today's new distributed base stations. The RRH contains the base station's RF circuitry plus analog-todigital/digital-to-analog converters and up/down converters. RRHs also have operation and management processing capabilities and a standardized optical interface to connect to the rest of the base station. This will be increasingly true as LTE and WiMAX are deployed. Remote radio heads make MIMO operation easier; they increase a base station's efficiency and facilitate easier physical location for gap coverage problems. RRHs will use the latest RF component technology including Gallium nitride (GaN) RF power devices and envelope tracking technology within the RRH RF power amplifier (RFPA). RRH PROTECTION IN FIBER TO THE ANTENNA SYSTEMS Fourth generation (4G) and beyond infrastructure deployments will include the implementation of Fiber to the Antenna (FTTA) architecture. FTTA architecture has enabled lower power requirements, distributed antenna sites, and a reduced base station footprint than conventional tower sites. The use of FTTA will promote the separation of power and signal components from the base station and their relocation to the top of the tower mast in a Remote Radio Head (RRH). According to the Telcordia industry standard that establishes generic requirements for Fiber to the Antenna (FTTA) protection GR-3177,the RRH shifts the entire highfrequency and power electronic segments from the base station to a location adjacent to the antenna. The RRH will be served by optical fiber and DC power for the optical-toelectronic conversion at the RRH. RRHs located on cell towers will require Surge Protective Devices (SPDs) to protect the system from lightning strikes and induced power surges. There is also a change in electrical overstress exposure due to the relocation of the equipment from the base station to the top of the mast. PROTECTION FROM LIGHTNING DAMAGE RRHs can be installed in a low-profile arrangement along a rooftop, or can involve a much higher tower arrangement. When installed at the highest point on a structure (whether a building or a dedicated cell tower), they will be more vulnerable to receiving a direct lightning strike and higher induced lightning levels, compared with those installed in a lower profile manner below the upper edges of the building. As noted in GR-3177, while surges can be induced into the RRH wiring for lightning striking the nearby rooftop or even the base station closure, the worst case will occur when a direct strike occurs to the antenna or its supporting structure. Designing the electrical protection to handle this situation will provide protection for less damaging scenarios it can also be use in optical fiber communication but different type. CONCLUSION In order to have best of Network and throughput from it backhaul is of at most importance. Introduction of cloud RAN has open the path for low latency network and path for future radio technologies. 3 KPI REPORTS FOR 2G/3G/4G LEARNING OBJECTIVE After completing this chapter participants will able to understand: Key Performance Indicators (KPIs) of 2G/3G/4G Quality of Service (QoS). Reports of KPIs QoS parameters related to Network Accessibility, Service Accessibility, and Network Retain ability. INTRODUCTION Key Performance Indicators are a set of quantifiable measures used in GSM, UMTS, HSPA, and LTE networks to gauge or compare performance in terms of meeting mobile network’s strategic and operational goals. KPIs vary between management, marketing, operations and network engineering people depending on their priorities, perspectives or performance criteria sometimes referred to as “Key Success Indicators (KSI)”. KPI OF GSM In GSM all the events being occurred over air interface are triggering different counters in the Base Station Controller (BSC). The KPIs are derived with the help of these counters using different formulations. RF Optimizer makes frequent use of statistical data for routine optimization activities. This raw data, which is actually based on counters, makes optimization tasks quite cumbersome as counters are in thousands. So, to make the tasks simpler, counters are appended into formulae, whereas, each formula reflects a specific performance indicator. All major performance indicators are categorized as Key Performance Indicators (KPIs). The KPIs are available in report form through OMC. Following 2G network KPI optimizations are covered in this chapter: SDCCH congestion Rate SDCCH drop Rate TCH congestion/Blocking Rate Call Setup Success Rate TCH (call) drop Rate Handover Success Rate Paging Success Rate RACH Success Rate Data KPI improvement SDCCH CONGESTION RATE During Location Update and set up of MO and MT calls, MS usually seizes SDCCH to exchange signaling. SMS is also sent/delivered through SDCCH channel in idle mode. When BSC receives SDCCH request from MS, it checks SDCCH resource. If all SDCCHs are occupied at that moment, SDCCH congestion takes place. Its day average value should be ≤ 1%. Causes and solutions: (a) Large traffic volume exceeding network capacity Solution: Increase cell capacity by adding more TRXs. (b) Too many location update at LAC boundaries Solution: (i) Adjust LAC selection and/or modify LAC boundaries (ii) Adjust CRH (Cell Reselection Hysteresis) (iii) Adjust parameter setting of periodic location update timer (T3212) (c) Too much SMS traffic Solution: (i) Implement dynamic SDCCH allocation mode (ii) Increase SDCCH channels (d) Hardware fault in TRX or transmission system (Abis link etc.) Solution: (i) Replace the faulty hardware (ii) Check and repair the transmission system (e) Unreasonable setting of system parameters and RACH parameters Solution: (i) Increase RACH access threshold appropriately to cope with interference (ii) Reduce Max Retrains appropriately SDCCH DROP RATE: When MS is already on SDCCH and in-between communication with Base station SDCCH channel got disconnected abruptly then SDCCH Drop has occurred. Process for Optimization: Identify the Bad performing Cells for SDCCH Drop Rate. Then follow the below mentioned Process after Analyzing detailed report a) The Main Reasons for High SDCCH Drop Rate are improper Parameters Configuration and Bad RF & Environmental factors. b) First Audit for any parameters related discrepancies and define as per standard parameters set. c) Check for Neighbor Relations and correct if it is not proper. d) Low Coverage: Through Drive Test Find out the low coverage patched and try to improve the coverage. e) Interference: Check for interference from repeaters, Intra-Network interference due to aggressive reuse or improper Frequency, Inter-Network can also be the case. Find out the actual cause and rectify it. f) Antenna System: High VSWR due to feeders, improper antenna configuration (Ex. Sector cable Swap) g) Check for Hardware Issue and rectify if you found any. h) After the activity check the subsequent days report and repeat the procedure for pin pointing the actual cause. TCH CONGESTION/BLOCKING RATE If during call attempt MS is not getting a TCH as all the available TCH in the cell are already occupied, TCH congestion/blocking occurs. Its day average value should be ≤ 2%. Process for Optimization Check TRX/Hardware Fault in the affected cell Check carried Traffic (Erlang) from BH Report and increase no. of TRX in the cell (If possible). No. of TCH required according to traffic can be analyzed from Erlang-B table (please see the table) Implement Half Rate/AMR-Half Rate if already maximum no. of TRX is equipped. Explore possibilities of sharing the traffic of affected cell with neighboring cell by: Antenna azimuth/tilt/height adjustment of affected/ neighboring cells. HO margin adjustment for making logical slope to neighboring cells. Directed Retry/Traffic handover may be enabled. In very exceptional cases power of affected cell may be reduced. Additional sector may be installed in the affected BTS. Dual band may be implemented in the affected BTS to increase no. of TRX. Last option: Introduction of new BTS in the affected area Table 2. Erlang B Table CALL SETUP SUCCESS RATE (CSSR) CSSR indicates the probability of successful calls initiated by MS. It is an important KPI for evaluating the network performance. If CSSR is too low, the subscribers are not likely to make calls successfully. Its value should be ≥95% CSSR value depends on I. SDCCH Assignment success Rate II. SDCCH Drop Rate III. TCH Assignment Success Rate Process of optimisation Find out the causes of a low CSSR.(Check whether a low CSSR is caused by SDCCH/Immediate Assignment Success Rate problems, SDCCH Drop Rate problems, or TCH Assignment Success Rate problems.) and accordingly following actions may be taken a) Minimise SDCCH Congestion (Refer SDCCH Congestion in the same chapter) b) Minimise SDCCH Drop (Refer SDCCH Drop in the same chapter) c) Minimise TCH Congestion (Refer TCH Congestion in the same chapter) d) Check Hardware/Transmission Faults and Feeder Cable Swap (if any) e) Check value of parameters like RXLEV_ACCESS_MIN/RACH Min Access Level/Tx-integer etc. CALL DROP RATE Call drops are identified through SACCH messages. A Radio Link Failure counter (RLT) value is broadcast on the BCH. The counter value may vary from network to network. At the establishment of a dedicated channel, the counter is set to the broadcast value (which will be the maximum allowable for the connection). The mobile decrements the counter by 1 for every FER (unrecoverable block of data) detected on the SACCH and increases the counter by 2 for every data block that is correctly received (up to the initial maximum value). If this counter reaches zero, a radio link failure is declared by the mobile and it returns back to the idle mode. If the counter reaches zero when the mobile is on a SDCCH then it is an SDCCH Drop. If it happens on a TCH, it is a TCH drop. Sometimes an attempted handover, which may in itself have been an attempt to prevent a drop, can result in a dropped call. When the quality drops, a mobile is usually commanded to perform a handover. Sometimes however, when it attempts to handover, it finds that the target cell is not suitable. When this happens it jumps back to the old cell and sends a Handover Failure message to the old cell. At this stage, if the handover was attempted at the survival threshold, the call may get dropped anyway. If on the other hand the thresholds were somewhat higher, the network can attempt another handover. Call Drop Rate should be ≤ 2%. Causes of call drop a) Blind spot, low coverage level. b) Unavoidable interference can be the inter network interference, interference from repeaters, or intra network interference resulting from aggressive frequency reuse. c) Poor transmission quality and unstable transmission links over the Abis interface end other interfaces. d) Faulty hardware/high VSWR/ Feeder Cable swap e) Unreasonable settings of handover parameters/during inter BSC/MSC handover. f) If pre-emption is used in MSC then lower priority MS will face call drop. g) Unreasonable setting of radio parameters. Process of optimisation a) Check radio parameters. Adjust unreasonable settings of radio parameters. b) Proper frequency plan viz. achieve minimum interference level by proper BCCH planning, HSN, MAIO planning. c) Minimizing coverage holes by physical optimization (Orientation, Height, E.Tilt, M.Tilt). d) Setting Radio link timeout parameter as per inter site distance viz. for rural sites RLT can be of higher value. e) Similar for Rural site where uplink quality is poor, Rxlev Access min, Rach Access min parameter can be set appropriately. Proper balance should be maintained for this parameter else path imbalance will result and TCH drop will increase. f) Minimize Abis and other interface fluctuation – Link stability plays very vital role. g) Check and remove BTS/BSC hardware fault and Cable swap/high VSWR (if any). h) During HO to neighbour cells should be having free TCH resources else call drop may increase. For this proper half rate thresholds should be defined as per traffic pattern, decongestion of these cells by capacity argument. i) Proper Neighbour definition should be maintained – some handovers cannot be performed and thus call drops. HANDOVER SUCCESS RATE (HOSR) Handovers are meant for maintaining call continuity when subscriber crosses over from one cell to another cell. KPI to be monitored for handover performance in GSM is “Handover Success Rate”. Handover Process: The overall handover process is implemented in the MS, BSS & MSC. Measurement of radio subsystem downlink performance and signal strengths received from surrounding cells, is made in the MS. These measurements are sent to the BSS for assessment. The BSS measures the uplink performance for the MS being served and also assesses the signal strength of interference on its idle traffic channels. Initial assessment of the measurements in conjunction with defined thresholds and handover strategy may be performed in the BSS. Assessment requiring measurement results from other BSS or other information resident in the MSC, may be perform. In the MSC. The MS assists the handover decision process by performing certain measurements. When the MS is engaged in a speech conversation, a portion of the TDMA frame is idle while the rest of the frame is used for uplink (BTS receive) and downlink (BTS transmit) timeslots. During the idle time period of the frame, the MS changes radio channel frequency and monitors and measures the signal level of the six best neighbor cells. Measurements which feed the handover decision algorithm are made at both ends of the radio link. Process of optimisation a) Identify the Bad performing Cells for HOSR b) Take the detailed report showing cause & target cell c) Check whether HO parameters are defined correctly. d) BCCH & BSIC confusion i.e. check whether same BCCH and BSIC combination is repeated in nearby cells. e) Minimise TCH Congestion as TCH congestion in target cell results HO fail. f) Unnecessary Handovers – more number of handovers, higher risk of facing quality problem and even in call drop g) Missing neighbour – Best server is not in there in neighbour list h) Feeder cable swap i) One way neighbor handover j) If neighbour is defined through external cells (between cells in different OMC servers e.g. 2G-3G HO/HO b/w cells of different vendors) - need to define correct CGI, BCCH, BSIC etc. in external cells. PAGING SUCCESS RATE Paging Success rate is the percentage of valid page responses received by the system. Paging Channel Congestion should be ≤ 1%. Process of optimisation a) Removal of non-existing Cell site database created in BSCs b) Correct LAC dimensioning; split LA if paging discard is due to big LA. c) Define correct channel configuration for CCCH. Avoid combining SDCCH in the BCH+CCCH timeslot. d) Remove SDCCH congestion in network as page response is sent to network through SDCCH. e) Eliminate Abis /A interface congestion/error. f) Correcting the various Paging/Location Update timers/parameters in MSC/BSC/Cell. g) Poor Paging Success rate is also observed due to poor RF environment (Site outage/ Poor Signal Level etc.). h) Use correct paging strategy according to network size and topology. RACH SUCCESS RATE Random Access Channel (RACH) is used by the MS on the “uplink” to request for allocation of an SDCCH. This request from the MS on the uplink could either be as a page response (MS being paged by the BSS in response to an incoming call) or due to user trying to access the network to establish a call. For all services there will CH REQ (Channel Request) from MS and in the response of CH REQ if MS will get the IMM ASS CMD (Signaling Ch.) Access to system is successful. Nature of this Access REQ is random so it is call Random Access Channel Request. Process of optimisation a) Identify the Bad performing Cells for RACH Success Rate b) Take detailed report and analyze for no of failure of Request and failures. c) The main reasons for bad RACH success rate could be access from very distant place with very low coverage; Parameters Configuration discrepancies. d) First Check for Parameters Configuration discrepancies and correct as per standard parameter set. e) The main parameters to be verified are: “MS MAX Retrains” allows the MS to retransmit again for AGCH by not incrementing the RACH access failure counter. It can set depending upon Traffic and Clutter. “Tx-Integer” will reduce the RACH collision and can improve RACH success rate. “T3122” waiting time for next network access. “RACH Min.Access Level (dbm)” very important parameter for low coverage rural areas. “CCCH conf” & “BS_AG_BLKS_RES” check properly defined or not? Because if you have overload with AGCH “IMM ASS” can’t be send in the response of CH REQ. f) Check for Hardware Issues (Ex. BTS sensitivity has very crucial role to play here) g) Check for Uplink Interference and quality. i) Check for UL-DL imbalance and correct if any problem. DATA KPI IMPROVEMENT TBF SUCCESS RATE Temporary Block Flow (TBF) is a physical connection used by the two Radio Resource entities to support the unidirectional transfer of PDUs on packet data physical channels. The TBF is allocated radio resource on one or more PDCHs and comprises a number of RLC/MAC blocks carrying one or more LLC PDU. TBF Success Rate is when during a data session, TBFs are successfully established on UL and DL. Process of optimisation a) Identify the Bad performing Cells for TBF Success Rate. b) Identify the bifurcation of Poor TBF Success Rate: whether UL or DL is poor or it is poor in both directions. c) Take the detailed report showing (Ex. Total TBF Requests, Total TBF Success, Failure reasons) d) Identify the failure reasons after analyzing detailed report and follow the below mentioned process. Failure is mainly due to TBF Congestion or MS No response. TBF CONGESTION: i. Check the Static and Dynamic PDCH definition from BSC Configuration data) If you find Zero Static or Dynamic PDCH, define the same. ii. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. iii. Check Hardware/TRX alarms; Resolve if find any. iv. Audit for any parameters related discrepancies and define as per standard parameters set. MS No Response: RF and Environmental Factors: i. Low Coverage Areas (Try to reduce low coverage patches with physical optimization; New sites) ii. Interference/ Bad quality/ UL-DL Imbalance; iii. Check the states for TRx on which PDCH is configured can be issue of TRx also; Change TRx if you found random behavior of TRx. AVERAGE GPRS/EDGE RLC THROUGHPUT Throughput is the amount of data uploaded/downloaded per unit of time. Process of optimisation a) Identify the Bad performing Cells for Poor GPRS/EDGE Throughput. b) Identify the bifurcation of Poor Throughput: whether UL or DL is poor or it is poor in both directions. c) Take the detailed report showing (Ex. Total TBF Requests, Coding Scheme Utilization) d) Identify the cells after analyzing detailed report and follow the below mentioned process. e) Take the configuration dump of the poor cells: I.Check The Static and Dynamic PDCH definition from BSC Configuration data) II.If you find Zero Static or Dynamic PDCH, define the same. III.If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. IV.Check whether there are enough Idle TS defined at the site. If not, definition to be done. f) Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. g) Check Gb Congestion/Utilization at the BSC/PCU. h) Check Hardware/TRX alarms; Resolve if find any. i) Audit for any parameters related discrepancies and define as per standard parameters set. DOWNLINK MULTI SLOT ASSIGNMENT SUCCESS RATE User timeslot request based on traffic types and MS multi-timeslot capability and the actual timeslot allocated by the system which can also be termed as Downlink Multislot Assignment Success rate. Process of optimisation a) Identify the Bad performing Cells for Poor DL Multislot Assignment. b) Take the detailed report showing (Ex. Total TBF Requests, Failure in terms of TS requests) c) Identify the cells after analyzing detailed report and follow the below mentioned process. d) Take the configuration dump of the poor cells: I. Check The Static and Dynamic PDCH definition from BSC Configuration data) II. If you find Zero Static or Dynamic PDCH, define the same. III. If PDCH definition is sufficient as per the guidelines, then check whether the TBF requests are high. If requests are high, then we need to define more PDCHs in the cell. But before defining more PDCHs, check whether the Voice Utilization is not high and there is no TCH Congestion in the cell. IV. Check the multiplexing thresholds and upgrade/downgrade reports. e) Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive test to analyze the cell in more detail. f) Check Gb Congestion/Utilization at the BSC/PCU. g) Check Hardware/TRX alarms; Resolve if find any. h) Audit for any parameters related discrepancies and define as per standard parameters set. 3G UMTS KPI 3G KPIS ARCHITECTURE Figure 14: 3G KPI Structure RAN KPI Class: Figure 15: 3G KPI Class 4G LTE KPI As specified in the 3GPP TS 32.451 document, there are several types of KPI parameters that are integral to any LTE network, depending on the target they measure: Accessibility Retainability Integrity Availability Mobility Others can be added depending on the network’s need, such as: Utilization Traffic Latency Accessibility Accessibility is a measurement that allows operators to know information related to the mobile services accessibility for the subscriber. The measurement is performed through E-UTRAN’s E-RAB service. Retainability Retainability measures how many times a service was interrupted or dropped during use, thus preventing the subscriber to benefit from it or making it difficult for the operator to charge for it. Therefore, a high Retainability is very important from a business stand point. The measurement is performed through E-UTRAN’s E-RAB service. Integrity Integrity measures the high or low quality of a service while the subscriber is using it. The measurement is performed through E-UTRAN’s delivery of IP packets. Availability Availability measures a service’s availability for the subscriber. The measurement is performed by determining the percentage of time that the service was available for the subscribers served by a specific cell. The measurement can also aggregate data from more cells or from the whole network. Mobility Mobility measures how many times a service was interrupted or dropped during a subscriber’s handover or mobility from on cell to another. The measurement is performed in the E-UTRAN and will include Intra E-UTRAN and Inter RAT handovers. KPIs for LTE RAN (Radio Access Network) INDICATORS LTE KPI Accessibility KPI RRC setup success rate ERAB setup success rate Call Setup Success Rate Are used to measure properly of whether services requested by users can be accessed in given condition, also refers to the quality of being available when users needed. eg. user request to access the network, access the voice call, data call,...... Retainability KPI Call drop rate Service Call drop rate Are used to measure how the network keep user's possession or able to hold and provide the services for the users Mobility KPI Integrity KPI Availability KPI Utilization KPI Intra-Frequency Handover Out Success Rate Inter-Frequency Handover Out Success Rate Inter-RAT Handover Out Success Rate (LTE to WCDMA) Are used to measure the performance of network which can handle the movement of users and still retain the service for the user, such as handover,... E-UTRAN IP Throughput IP Throughput in DL E-UTRAN IP Latency Are used to measure the character or honesty of network to its user, such as what is the throughput, latency which users were served. E-UTRAN Cell Availability Partial cell availability (node restarts excluded) Are used to measure how the network keep user's possession or able to hold and provide the services for the users Mean Active Dedicated EPS Bearer Utilization Are used to measure the utilization of network, whether the network capacity is reached its resource. Table 3. LTE KPI TYPE OF REPORTS “Time consistent Busy hour” or “TCBH” means the one hour period starting at the same time each day for which the average traffic of the resource group concerned is greatest over the days under consideration and such Time Consistent Busy Hour shall be established on the basis of analysis of traffic data for a period of ninety days; Cell Bouncing Busy Hour (CBBH) means the one hour period in a day during which a cell in cellular mobile telephone network experiences the maximum traffic. Whole Day/Day Average Report means value of concerned indicator is calculated over whole day period or day average is taken. SAMPLE TRAFFIC REPORTS BSC PERFORMANCE REPORT CELL/ TRX PERFORMANCE REPORT CONCLUSION KPIs are important as they calibrate the network to a specific level. With KPIs, standardization of network can be done 4 3G MOBILE NETWORK LEARNING OBJECTIVE After completion of this chapter student will able to understand: The Universal Mobile Communication Services (UMTS) and its benefits over the 2G mobile Communication Technologies used in UMTS Wideband Code Division Multiple Access technology WCDMA Radio network system architecture. UMTS core network elements Various domains in 3G Core Network INTRODUCTION 3G refers to the 3rd generation of mobile telephony (that is cellular) technology. The 3rd generations the name suggests, follow two earlier generations. The 1st generation (1G) began in the early80’s with commercial development of advanced mobile phone service (AMPS) cellular networks. Early AMPS network used frequency division multiple access (FDMA) to carry analogy voice over channels in the 800MHZ frequency band. The 2nd generation (2G) emerged in the 90’s when mobile generators deployed two competing digital voice standards. In the North America, some operators adopted IS-95, which uses CDMA to multiplex up to 64 calls per channel in the 800MHZ band. Across the world, many operators adopted the global system for mobile communication (GSM) standard, which used the time division multiple accesses (TDMA) technique to multiplex up to 8 calls per channel in the 900MHZ and 1800MHZ spectrum bands. The international telecommunication union (ITU) defined the 3rd generation (3G) of mobile telephony standards IMT-2000 to facilitate growth, increase bandwidth and support more diverse applications. Some of the limitations of 2Gsystems, it’s only voice oriented, it has limited data capabilities, no worldwide (WW) roaming and incompatible system in different countries. Despite the extension of 2G system i.e. 2.5G such as GPRS and EDGE, which provides the enhanced facilities and much improved data rates, but there was still incompatibility issues and WW-roaming problems. Therefore, there was a need of a system that could provide more advanced services. Some of the features of the 3G systems are: Bit rates up to 2Mbps Variable bit rate to offer bandwidth on demand Multiplexing of services with different Qos requirements on a single connection Quality requirements from 10% frame error rate to 10-6 bit error rate. Co-existence with different systems and inter-system handovers for coverage enhancement sand loading balancing. Uplink and downlink asymmetry e.g. web browsing causes more loading to downlink than to uplink. High spectrum efficiency Co-existence of FDD (Frequency division duplex) and TDD (time division duplex) modes 3G STANDARDS AND WCDMA RELEASES Universal Mobile Telecommunication System (UMTS) is the standard for European 3G based WCDMA systems which turned out to be the preferred solution for countries with 2G because of its high data capability. The 3rd Generation Partnership Project (3GPP) manages the UMTS and has assumed responsibility for the continued standardization of GSM since July 2000. If we recall the first commercial UMTS network was deployed in 2001 by NTT Do Como in Japan after since then other countries soon took the same step in deploying the network including Germany, UK, France etc. During the development of the UMTS specifications for the WCDMA systems within the3GPP, it went through a series of phases and continuous update for instance the first UMTS specification released which is known as the 3GPP Release-99 which was functionally frozen in December 1999, which then implemented similar services with those of GSM phase 2+(GPRS/EDGE). However the 3G network might still offer additional services which are not available on the GSM platform e.g. video call. In the second phase brought about the3GPP Release- 4 which would introduce mainly an all IP-Core Network which would allow for the separation of call signalling and control from all actual connections i.e. within the core network the flow of data will pass through a media gateway (MGW) which would in turn maintain the connection and perform other switching functions this approach was known as Soft Switching, however release-4 became frozen in march 2001because of newer releases to be introduced. After a while there was another release termed as the 3GPP Release 5 which introduced the IP Multimedia Subsystem (IMS) which would unify and perform all IP based multiservice i.e. a combination of more than one service on a physical channel to a user e.g. voice & video or image. The introduction of HSDPA and wide band AMR services are evolution of the Air Interface in order to enhance the speed of the data rate, which was done by integrating the voice data on the dedicated channel and data on the downlink shared channel are all multiplexed and carried on the same carrier which allows for speed up to 14.Mbps. However release 5 specifications were soon frozen in 2002, nevertheless subsequent releases within the specifications occur mainly with the transport technology; basically the changes are made to improve the flexibility and efficiency of the operating network. UMTS is an International Mobile Telecommunications - 2000 (IMT-2000) 3G system. The other main IMT–2000 system proposed by the ITU is CDMA 2000. Figure 16: 4.1 3G Standardization Environment Overview of UMTS release architectures This section provides a general description of the current standard UMTS release architectures. UMTS architectures provide a smooth transition from second generation telecommunications systems by slowly phasing in new software and new network elements. a) 3GPP currently defines standards for the following UMTS releases b) 3GPP Release 99 (R99), c) 3GPP Release 4 (Next Generation Network (NGN) architecture), d) 3GPP Release 5 (all-IP core network). Note : Release 2000 (R00) is split into “Release 4” and “Release 5”. WCDMA RADIO ACCESS NETWORK The main purpose of the WCDMA Radio Access Network is to provide a connection between the handset and the core network and to isolate all the radio issues from the core network. The advantage is one core network supporting multiple access technologies. The WCDMA Radio Access Network consists of two types of nodes: Figure 17: WCDMA Radio Access Network RADIO BASE STATION (NODE B) The Radio Base Station handles the radio transmission and reception to/from the handset over the radio interface (Uu). It is controlled from the Radio Network Controller via the Iub interface. One Radio Base Station can handle one or more cells. Figure 18: WCDMA Node B FUNCTIONS OF NODE B: Radio transmission and reception handling Involved in the mobility management Involved in the power control Modulation / Demodulation Closed loop power control RADIO NETWORK CONTROLLER (RNC) The Radio Network Controller is the node that controls all WCDMA Radio Access Network functions. It connects the WCDMA Radio Access Network to the core network via the Iu interface. There are two distinct roles for the RNC, to serve and to control. The Serving RNC has overall control of the handset that is connected to WCDMA Radio Access Network. It controls the connection on the Iu interface for the handset and it terminates several protocols in the contact between the handset and the WCDMA Radio Access Network. The Controlling RNC has the overall control of a particular set of cells, and their associated base stations. Figure 19: Radio Network Controller Main Functions of this Intelligent part of UTRAN System includes; Radio resource management (code allocation, Power Control, congestion control, admission control) Call management for the users Connection to CS and PS Core Network Radio mobility management When a handset must use resources in a cell not controlled by its Serving RNC, the Serving RNC must ask the Controlling RNC for those resources. This request is made via the Iur interface, which connects the RNCs with each other. In this case, the Controlling RNC is also said to be a Drift RNC for this particular handset. This kind of operation is primarily needed to be able to provide soft handover throughout the network. RADIO ACCESS BEARERS The main service offered by WCDMA RAN is the Radio Access Bearer (RAB). To establish a call connection between the handset and the base station a RAB is needed. Its characteristics are different depending on what kind of service/information to be transported. The RAB carries the subscriber data between the handset and the core network. It is composed of one or more Radio Access Bearers between the handset and the Serving RNC, and one Iu bearer between the Serving RNC and the core network. 3GPP has defined four different quality classes of Radio Access Bearers: Conversational (used for e.g. voice telephony) – low delay, strict ordering Streaming (used for e.g. watching a video clip) – moderate delay, strict ordering Interactive (used for e.g. web surfing) – moderate delay Background (used for e.g. file transfer) – no delay requirement 3G CORE NETWORK (CN) The 3G UMTS core network architecture is a migration of that used for GSM with further elements overlaid to enable the additional functionality demanded by UMTS. The core network provides all the central processing and management for the system. The CN is similar to the network and switching subsystem (NSS) of the GSM architecture. The main function of the CN is to perform packet routing, connection of users, security, billing etc. The core network is the overall entity that interfaces to external networks including the public phone network and other cellular telecommunications networks. The UMTS Core Network elements can be categorised into two domains depending on the type of traffic and functions they handle. Circuit switched elements: These elements are primarily based on the GSM network entities and carry data in a circuit switched manner, i.e. a permanent channel for the duration of the call. Packet switched elements: These network entities are designed to carry packet data. This enables much higher network usage as the capacity can be shared and data is carried as packets which are routed according to their destination. Figure 20: UMTS Core Network CIRCUIT SWITCHED CORE NETWORK The circuit switched elements of the UMTS core network architecture include the following network entities: MOBILE SWITCHING CENTRE (MSC): The MSC is the interface between the Radio Access Network (RAN) and fixed networks. It provides mobility management, call control and switching functions to enable circuit-switched services to and from mobile stations. GATEWAY MSC (GMSC): The GMSC interfaces with the fixed networks, handles subscriber location information from the HLR and performs routing functions to and from mobile stations. GMSC functionality can be contained in all or some of the MSCs of the network, depending on network configuration. PACKET SWITCHED ELEMENTS Packet Switched core network includes elements that support packet switching technology. Packet-switching technology routes packets of user data independently of one another. No dedicated circuit is established. Each packet can be sent along different circuits depending on the network resources available. The packet switched elements of the 3G UMTS core network architecture include the following network entities: SERVING GPRS SUPPORT NODE (SGSN): As the name implies, this entity was first developed when GPRS was introduced, and its use has been carried over into the UMTS network architecture. The SGSN provides a number of functions within the UMTS network architecture. Mobility Management: When a UE attaches to the Packet Switched domain of the UMTS Core Network, the SGSN generates MM information based on the mobile's current location. Session Management: The SGSN manages the data sessions providing the required quality of service and also managing what are termed the PDP (Packet data Protocol) contexts, i.e. the pipes over which the data is sent. Interaction with other areas of the network: The SGSN is able to manage its elements within the network only by communicating with other areas of the network, e.g. MSC and other circuit switched areas. Billing: The SGSN is also responsible billing. It achieves this by monitoring the flow of user data across the GPRS network. CDRs (Call Detail Records) are generated by the SGSN before being transferred to the charging entities (Charging Gateway Function, CGF). GATEWAY GPRS SUPPORT NODE (GGSN): Like the SGSN, this entity was also first introduced into the GPRS network. The Gateway GPRS Support Node (GGSN) is the central element within the UMTS packet switched network. It handles inter-working between the UMTS packet switched network and external packet switched networks, and can be considered as a very sophisticated router. In operation, when the GGSN receives data addressed to a specific user, it checks if the user is active and then forwards the data to the SGSN serving the particular UE. BORDER GATEWAY (BG) The BG provides connectivity, and interworking and roaming capabilities between two different PLMNs. SHARED ELEMENTS Some network elements, particularly those that are associated with registration are shared by both domains and operate in the same way that they did with GSM. The shared elements of the 3G UMTS core network architecture include the following network entities: HOME LOCATION REGISTER (HLR) This database contains all the administrative information about each subscriber along with their last known location. In this way, the UMTS network is able to route calls to the relevant RNC / Node B. When a user switches on their UE, it registers with the network and from this it is possible to determine which Node B it communicates with so that incoming calls can be routed appropriately. Even when the UE is not active (but switched on) it re-registers periodically to ensure that the network (HLR) is aware of its latest position with their current or last known location on the network. VISITOR LOCATION REGISTER(VLR) The VLR manages mobile subscribers in the home PLMN and those roaming in a foreign PLMN. The VLR exchanges information with the HLR. EQUIPMENT IDENTITY REGISTER (EIR) The EIR is the entity that decides whether a given UE equipment may be allowed onto the network. Each UE equipment has a number known as the International Mobile Equipment Identity. This number, as mentioned above, is installed in the equipment and is checked by the network during registration. AUTHENTICATION CENTRE (AUC) The AuC is a protected database that contains the secret key also contained in the user's USIM card. EQUIPMENT IDENTITY REGISTER (EIR) The EIR stores information on mobile equipment identities. SMS MSCS SMS MSCs enable the transfer of messages between the Short Message Service Center and the PLMN. ENHANCEMENT IN UMTS ARCHITECTURE IN FUTURE RELEASES The first enhancement was the bearer independent circuit switched core network in release 4. In this architecture, the mobile switching centre is split in two. The circuit switched media gateway (CS-MGW) handles the traffic functions of the MSC, but uses different transport protocols that we will see in the next section. It also includes a media conversion function, which allows it to communicate with networks that are using other types of transport protocol. The MSC server combines the signaling functions of the MSC with those of the VLR, and also controls the CS-MGW over a signaling interface that lies between them. A GMSC server is built in the same way. The main network enhancement in release 5 is the IP multimedia subsystem (IMS). This is an extra network which interfaces with the packet switched domain, and which provides users with real time packet switched services that cannot be supplied using the packet switched domain alone. The home subscriber server (HSS) was also introduced in release5, and combines the functions of the HLR and the AuC. The third release5 enhancement (not shown in the figure) is an architectural feature known as IuFlex. In earlier releases, each radio network controller was connected to just one MSC and one SGSN. IuFlex introduces a more flexible architecture in which each RNC can be connected to multiple MSCs and multiple SGSNs. The main release 6 enhancement is wireless local area network (WLAN) interworking. This allows users to access the network operator’s packet switched services using a wireless LAN. The services are supplied either by the IMS, or by data servers that are controlled by the network operator and directly connected to a GGSN. The connection uses some extra core network components that are not shown in the figure, known as the WLAN access gateway (WAG) and packet data gateway (PDG). CONCLUSION WCDMA is very successful technology due to its robust radio network design. By virtue of WCDMA and frequency reuse the capacity and of WCDMA system is increased tremendously. But with the introduction of Data on mobile WCDMA has lost its shine as it deliveries very less data rates. Thus WCDMA has been migrated to newer technologies such as LTE and LTE Advance. 5 HSPA, HSPA+ LEARNING OBJECTIVE After completion of this chapter participant will able to understand about: HSAP and HSPA+ Standards Various releases HSPA and HSPA+ technology Migration to 4G UMTS HSPA AND 3GPP STANDARDS 3G HSPA provides a major improvement in performance to the 3G UMTS mobile telecommunications system. It provides additional facilities that are added on to the basic 3GPP UMTS standard. The top data rates for HSPA compete well with the 4G LTE technology. As such the 3G infrastructure usage was prolonged and enabled many operators to maximise the use of their investment before having to add the capability for 4G. The evolution of UMTS-HSPA happens in stages referred to as 3GPP Releases. The upgrades and additional facilities were introduced at successive releases of the 3GPP standard. Figure 1: 3GPP UMTS Evolution Release 4: This release of the 3GPP standard provided for the efficient use of IP, a facility that was required because the original Release 99 focussed on circuit switched technology. Accordingly this was a key enabler for 3G HSDPA. Release 5: This release included the core of HSDPA itself. It provided for downlink packet support, reduced delays, a raw data rate (i.e. including payload, protocols, error correction, etc) of 14 Mbps and gave an overall increase of around three over the 3GPP UMTS Release 99 standard. Release 6: This included the core of HSUPA with an enhanced uplink with improved packet data support. This provided reduced delays, an uplink raw data rate of 5.74 Mbps and it gave an increase capacity of around twice that offered by the original Release 99 UMTS standard. Also included within this release was the MBMS, Multimedia Broadcast Multicast Services providing improved broadcast services, i.e. Mobile TV. Release 7: This release of the 3GPP standard included downlink MIMO operation as well as support for higher order modulation up to 64-QAM in the uplink and 16-QAM in the downlink. However it only allows for either MIMO or the higher order modulation. It also introduced protocol enhancements to allow the support for Continuous Packet Connectivity (CPC). Release 8: This release of the standard occurred during the course of 2008 and it defines dual carrier operation as well as allowing simultaneous operation of the high order modulation schemes and MIMO. Further to this, latency is improved to keep it in line with the requirements for many new applications being used. Release 9: 3GPP Release 9 occurred during 2009 and included facilities for HPSA including 2x2MIMO in the uplink and a 10MHz bandwidth in the downlink. The uplink carriers may be from different bands. Release 10: HSPA Release 10 utilises up to 4-carriers, i.e. 20 MHz bandwidth which may be from two separate bands. In addition to this 2x2 MIMO in the downlink provides data rates up to 168 Mbps. This figure equates to that obtained for LTE Release 8 when using comparable bandwidth and antennas configurations. Release 11: Release 11 occurred during 2011 / 2012. It provided the facility for 40MHz bandwidth in the uplink along with up to 4x4 MIMO. The downlink was upgraded to accommodate 64-QAM modulation and MIMO. HSPA: HIGH SPEED PACKET ACCESS High speed packet access, HSPA is an upgrade to 3G UMTS to provide very high higher data rates in both uplink and downlink.3G UMTS enables mobile communications to move from voicecentric systems to data centric ones. However the speeds that could be supported were nowhere near sufficient to enable Internet surfing and video downloads. To overcome this 3G UMTS was upgraded with high speed packet access, HSPA to provide a major leap in performance and make it suitable to cover its requirements. Initially the downlink was addressed using high speed downlink packet access, HSDPA and then upgrades were added to the uplink with high speed uplink packet access. Further upgrades were added later with dual carrier and MIMO capabilities to raise the data speeds hugely above those first envisaged for 3G. HSPA BENEFITS The system provides an enhancement on the basic 3G WCDMA / UMTS cellular system, providing data transfer rates that are considerably in excess of those originally envisaged for 3G as well as much greater levels of spectral efficiency. The system provides many advantages for users over the original UMTS system. 3G HSPA SPEED & HIGHLIGHT FEATURES 3GPP RELEASE TECHNOLOGY Rel 5 Rel 6 Rel 7 HSDPA HSUPA 2xdata capacity 2x voice capacity Multi-carrier Rel 8 DOWNLINK SPEED (MBPS) 14.4 14.4 28 UPLINK SPEED (MBPS) 0.384 5.7 11 42 11 Rel 9 Rel 10 Rel 11 Multicarrier, 10 MHz, 2x2 MIMO UL, 10 MHz & 16-QAM D/L 20 MHz 2x2 MIMO in UL, 10 40 MHz 2x2 / 4x4 MIMO UL, 10 MHz 64-QAM MIMO DL Table 1. 84 23 168 23 336 - 672 70 3G HSPA SPEED & HIGHLIGHT FEATURES 3G HSPA FEATURES The UMTS cellular system as defined under the 3GPP Release 99 standard was orientated more towards switched circuit operation and was not well suited to packet operation. Additionally greater speeds were required by users than could be provided with the original UMTS networks. Accordingly the changes required for HSPA were incorporated into many UMTS networks to enable them to operate more in the manner required for current applications. HSPA provides a number of significant features that enable the new service to provide a far better performance for the user. While 3G UMTS HSPA offers higher data transfer rates, this is not the only feature, as the system offers many other improvements as well: 1. Use of higher order modulation: 16QAM is used in the downlink instead of QPSK to enable data to be transmitted at a higher rate. This provides for maximum data rates of 14 Mbps in the downlink. QPSK is still used in the uplink where data rates of up to 5.8 Mbps are achieved. The data rates quoted are for raw data rates and do not include reductions in actual payload data resulting from the protocol overheads. 2. Shorter Transmission Time Interval (TTI): The use of a shorter TTI reduces the round trip time and enables improvements in adapting to fast channel variations and provides for reductions in latency. 3. Use of shared channel transmission: Sharing the resources enables greater levels of efficiency to be achieved and integrates with IP and packet data concepts. 4. Use of link adaptation: By adapting the link it is possible to maximize the channel usage. 5. Fast Node B scheduling: The use of fast scheduling with adaptive coding and modulation (only downlink) enables the system to respond to the varying radio channel and interference conditions and to accommodate data traffic which tends to be "bursty" in nature. 6. Node B based Hybrid ARQ: This enables 3G HSPA to provide reduced retransmission round trip times and it adds robustness to the system by allowing soft combining of retransmissions. For the network operator, the introduction of 3G HSPA technology brings a cost reduction per bit carried as well as an increase in system capacity. With the increase in data traffic, and operators looking to bring in increased revenue from data transmission, this is a particularly attractive proposition. A further advantage of the introduction of 3G HSPA is that it can often be rolled out by incorporating a software update into the system. This means its use brings significant benefits to user and operator alike. 3G UMTS HSPA CONSTITUENTS There are two main components to 3G UMTS HSPA, each addressing one of the links between the base station and the user equipment, i.e. one for the uplink, and one for the downlink. The two technologies were released at different times through 3GPP. They also have different properties resulting from the different modes of operation that are required. In view of these facts they were often treated as almost separate entities. The two technologies are summarised below: HSDPA - High Speed Downlink Packet Access: HSDPA provides packet data support, reduced delays, and a peak raw data rate (i.e. over the air) of 14 Mbps. It also provides around three times the capacity of the 3G UMTS technology defined in Release 99 of the 3GPP UMTS standard. HSUPA - High Speed Uplink Packet Access: HSUPA provides improved uplink packet support, reduced delays and a peak raw data rate of 5.74 Mbps. This results in a capacity increase of around twice that provided by the Release 99 services. HSDPA : HIGH SPEED DOWNLINK PACKET ACCESS High Speed Downlink Packet Access enables high speed packet data up to 14.4 Mbps to be carried in the downlink of 3G UMTS. 3G HSDPA High Speed Downlink Packet Access provides additional capability to the basic 3G UMTS cellular telecommunications system. HSDPA was the first upgrade along the path to HSPA which enabled high speed data to be carried in both directions. However as much more data was carried in the downlink direction, HSDPA was standardised and implemented first to provide the maximum benefit as soon as possible. HSDPA TECHNOLOGIES The 3G HSDPA upgrade includes several changes that are built onto the basic 3GPP UMTS standard. While some are common to the companion HSUPA technologies added to the uplink, others are specific to HSDPA High Speed Downlink Packet Access, because the requirements for each direction differ. Additional channels: In order to be able to transport the data in the required fashion, and to provide the additional responsiveness of the system, additional channels have been added. To achieve the high speed data HSDPA uses new channels including: High Speed Downlink Shared Channel (HS-DSCH), High Speed Signaling Control Channel(HSSCCH), High Speed Dedicated Physical Control Channel (HS-DPCCH). Modulation: One of the keys to the operation of HSDPA is the use of an additional form of modulation. Originally W-CDMA had used only QPSK as the modulation scheme, however under the new system16-QAM which can carry a higher data rate, but is less resilient to noise is also used when the link is sufficiently robust. The robustness of the channel and its suitability to use 16-QAM instead of QPSK is determined by analyzing information fed back about a variety of parameters.

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