Functionality 2.1 Functionality of the mcBSC The mcBSC manages a variety of tasks ranging from channel administration to short messaging service. The most important basic and optional functionalities are explained briefly below. For more details, see BSS feature descriptions. 2.1.1 General functionalities Call control Basic Call provides speech and data services to the mobile subscriber by offering the means for establishing speech calls with half or full rate or data calls with full rate radio channels. Management of radio channels • Management of common signaling of traffic channel configurations • Management of traffic channels (TCH) and standalone dedicated control channels (SDCCH): • Resource management • Channel allocation • Link supervision • Channel release • Power control • Management of broadcast control channels (BCCH) and common control channels (CCCH): • Random access • Access grant • Paging • System information broadcast • Management of frequency hopping which enables effective use of radio resources and enhanced voice quality for GSM subscriber • Handovers Existing handover types are: • Intra-BSC, intra-cell (both intra-TRX and inter-TRX), which means that the handover takes place within the area controlled by the BSC and the mobile stays in the same cell • Intra-BSC, inter-cell, which means that the mobile stays in the area of the BSC but moves from one cell to another • Inter-BSC, both outgoing and incoming, which means that the mobile moves into the area of another BSC The handover threshold comparison includes the evaluation of uplink/downlink level, quality and interference, MS-BTS distance evaluation, the evaluation of a rapid field drop, the detection of a fast/ slow-moving mobile station (MS), the detection of a turnaroundcorner MS, power budget evaluation, and umbrella handover evaluation. If two or more criteria for a handover are present simultaneously, the handover is done
according to the priority order. GPRS/EDGE packet data handling • Connection establishment and management • Resource allocation • Scheduling • Data transfer • MS uplink power control • Gb load sharing (uplink) • Flow control (downlink) Maintenance The mcBSC offers the possibility for the following maintenance procedures: • Fault localization for the mcBSC • Reconfiguration of the mcBSC • Reconfiguration support to the BTS • Updating of the software in the mcBSC, Multicontroller TC (mcTC), and BTS Operation During normal operation, the mcBSC offers various possibilities for the operator: • Modification of the parameters of the mcBSC and the BTS • Modification of the radio network parameters • Configuration of the mcBSC hardware • Administration of the mcBSC equipment Measurements and observations To run the network effectively, that is, to minimize costs and maximize service quality to the subscriber, the information on the performance and service level of the mcBSC and the radio network is needed. It is useful to know how much traffic different cells carry, whether there is congestion on the SDCCH or TCH channels, and how many handovers are successful and how many fail. Traffic measurements provide this information. The mcBSC measures traffic, observes signaling events, and traces a specific call. It then forwards these results to NetAct for further processing. It allows to select measurements, needed at a particular time. mcBSC measurements are independent of one another even though they are handled through the same user interface. For more information on the measurements and observations of the mcBSC see the Counters/performance indicators section of the BSC documentation set. 2.1.2 Data and messaging services General packet radio service (GPRS) GPRS gives customers the benefits of instant IP connectivity on-the-move and of being continuously connected. GPRS provides the possibility of being charged only for transferred data in addition to more efficient use of limited air interface resources.
GPRS provides packet radio access for a GSM/GPRS mobile. The benefit of GPRS is that it can use the same resources as circuit-switched connections by sharing the overhead capacity. This means that one mobile uses the resources only for a short period of time, that is, when there is data to be sent or received. Resource sharing together with a very fast method of reserving radio channels makes the air interface usage even more efficient. GPRS coding schemes CS1-CS4 are supported. Enhanced Data rates for GSM Evolution (EDGE) EDGE, introduced in GSM/GPRS standard Release 99, boosts GSM/GPRS network capacity and data rates to meet the demands of wireless multimedia applications and mass market deployment. Nokia Siemens Networks EDGE Solution includes GPRS/EDGE for packet switched data. EDGE uses 200 kHz radio channels, which are the same as the current GSM channel widths. From a technical perspective, EDGE BSS allows the GSM and GPRS core network to offer a set of new radio access bearers. EDGE is designed to improve spectral efficiency through efficient link utilization with GMSK and 8-PSK modulation schemes, which can be alternated on the same radio slot according to radio channel conditions. With new modulation, EDGE increases the radio interface data throughput threefold on average compared to GPRS. Available EDGE Modulation and Coding Schemes MCS1-MCS9 provide optimal performance in all radio conditions. Multipoint Gb interface Multipoint Gb interface enables one packet control unit (PCU) or PCU pool to be connected to several SGSNs. This enhances the resilience of the system and provides the possibility of distributing the traffic load between the SGSNs. Different users in the same PCU can be connected to different SGSNs according to their load conditions. A PS pool area defines a group of PCUs, where an MS roams without the need to change the serving SGSN node. This reduces the need for signaling when, for example, an MS moves between the city centre and suburban areas within a single pool area. Multipoint Gb interface improves scalability and fault protection in the core network and thus leads to savings in capital expenditure. In case of failures in the GPRS core, the network remains operational with reduced SGSN capacity. Multipoint Gb interface also facilitates easy core network element upgrades and helps the operator to maintain revenue and increase end-user service quality.
Extended cell for GPRS/ EDGE Extended cell for GPRS/EDGE enables the use of GPRS/EDGE traffic in the extended radio coverage area of an extended cell. Traffic for a mobile station is supported so that the mobile station can move between coverage areas of the cell without breaking data
connections. Depending on the configuration of the cell, packet services can be provided up to 70 km from the BTS site. Super extended cell for GPRS/EDGE further enhances the cell radius up to 105 km. Circuit Switched Data services The mcBSC with mcTC supports the following bearer services, including both transparent and nontransparent data services, defined in GSM Specification ETS 300 904 with applicable ETSI/3GPP specifications: • Data Circuit Duplex (300-14400 bit/s) transparent/non-transparent • High Speed Circuit Switched Data • 14.4 kbits/s Data Traffic Channel • Telefax Automatic Group 3, Transparent • Short Message Service Functionality High Speed Circuit Switched Data (HSCSD) HSCSD application software provides accelerated data rates for end-user applications. HSCSD supports both transparent and non-transparent data services. A multiple set of basic resources is reserved for one HSCSD call, and up to four time slots can be used for an HSCSD call. HSCSD can be combined with 14.4 kbit/s data service for higher data speed rates. Multimedia message service (MMS) and short message service (SMS) The mcBSC forwards mobile originating and mobile terminating messages transparently. Cell broadcast messages (CB) CB provides the mcBSC with the short message service cell broadcast (SMSCB) capabilities defined by GSM recommendations. The SMSCB is a basic teleservice that is used for broadcasting short messages to mobile stations in a specified area within the PLMN. The input is MMI, local, or remote. Optionally CBC can be used as the input for CB messages. Inter-System Network-controlled cell re-selection (IS-NCCR) Cell re-selection is a basic cellular radio network operation, where the MS's contact point to the network is changed during MS network connection. Cell re-selection is performed by the MS. The target cell of the cell reselection can be selected by the network or autonomously by the MS. Inter-System Network-Controlled Cell Re-selection (IS-NCCR) gives the network the possibility to order a cell re-selection from a GSM cell to a WCDMA RAN cell instead of the autonomous selection done by the MS itself. With this feature, the network decides when the MS changes cell and which is the target cell. IS-NCCR introduces the possibility for the network to control timing and target cell selection in cell re-selection. The cell reselection criteria is as follows: • Service-based IS-NCCR selects 3G network according to SGSN Service UTRAN
CCO BSSGP procedure even if the serving cell signal level is good. • Coverage-based IS-NCCR selects 3G network as soon as it is available or when GSM coverage ends, depending on operator choice. IS-NCCR is application software and requires a valid license in the mcBSC. Inter-BSC Network-assisted cell change (IB-NACC) The Inter-BSC Network-Assisted Cell Change (IB-NACC) feature is an extension of NACC feature that provides assistance to the MS, when it moves from one cell to another cell inside the BSC. IB-NACC extends the functionality to provide the cell change assistance when the MS moves between different BSCs. When IB-NACC is in use, the network assists the MS changing cell by sending a set of system information messages of the target neighboring cell to the MS, while it is still camping on the source cell. The system information messages are exchanged between two BSCs using the RAN Information Management (RIM) protocol. The RIM protocol is an enhancement to BSSGP protocol and is used for a reliable BSC-to-BSC information exchange. This feature is controlled by the ON/OFF license key. Inter-System Network-assisted cell change (IS-NACC) The Inter-System Network-Assisted Cell Change (IS-NACC) feature is an extension of the IB-NACC feature that provides assistance to the MS, when it moves from one cell to another cell of a different BSC. The IS-NACC feature extends the functionality by providing the GSM system information to the WCDMA system. The WCDMA system may use this set of system information messages in cell change assistance, when the MS moves from a WCDMA cell to a GSM cell. The system information is transferred by BSC to RNC using the RIM protocol. The RIM protocol is an enhancement to BSSGP protocol and is used for a reliable BSC-to-RNC information exchange. This feature is controlled by the ON/OFF license key. Inter-System Network-assisted cell change for LTE (IS-NACC for LTE) The Inter-System Network-Assisted Cell Change for LTE (IS-NACC for LTE) feature is an extension of IB-NACC feature that provides assistance to the MS when it moves from one cell to another cell of a different BSC. The IS-NACC for LTE feature extends the functionality by providing the GSM system information to the LTE system. The LTE system may use this set of system information messages in cell change assistance, when the MS moves from an LTE cell to a GSM cell. The system information is transferred by the BSC to eNodeB using the RIM protocol. The RIM protocol is an enhancement to BSSGP protocol and is used for a reliable BSC-to-LTE information exchange. This feature is controlled by the ON/OFF license key.
Dual-band GSM operation The mcBSC supports the dual band network. The dual band operation supports dual band mobiles able to perform handovers between the GSM 900 and GSM 1800 bands,
between 800 and 1900 bands as well as GSM/EDGE 800/1800 during a call. Extended GSM 900 band The extended (E)GSM 900 band (tri band) supports the use of the ETSI specified GSM 900 frequency band extension, the area of 880-890 MHz uplink and 925-935 MHz downlink where available. This means that a total of 50 radio frequency channels are included in this E-GSM 900 band. For a GSM operator, the E-GSM 900 extension band can represent the most cost-effective way of adding capacity to his system if the primary GSM spectrum is used. Common BCCH There is an option that allows GSM 900 and GSM 1800 TRXs to share the same BCCH in the same cell. This functionality can be considered a progression from the integrated dual band BTS and EGSM 900 frequency band support (Tri Band). Common BCCH is also supported for GSM/EDGE 800/1900 frequency bands. Intelligent underlay-overlay (IUO) The IUO allows the operator to reuse frequencies more intensively and hence achieve a higher radio network capacity. In IUO the operating spectrum of a network is divided into regular frequencies and super-reuse frequencies. The overlay network uses regular frequencies and offers a continuous coverage area. The underlay network uses the super-reuse frequencies which are reused very intensively to provide the extended capacity.