E2-E3: CONSUMER MOBILITY CHAPTER-5 CDMA 2000 1x OVERVIEW (Date of Creation: 01-04.2011) Page: 1
CDMA 2000 1X Overview Introduction CDMA (code division multiple access) is a mobile digital radio technology that transmits streams of bits and whose channels are divided using codes (PN sequences).this a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. It is the second generation of CDMA digital cellular. Evolution of CDMA CDMA2000 has a relatively long technical history, and remains compatible with the older CDMA telephony methods (such as CDMA One) first developed by Qualcomm, a commercial company, and holder of several key international patents on the technology. The CDMA2000 standards CDMA2000 1x, CDMA2000 1xEV-DO, and CDMA2000 1xEV-DV are approved radio interfaces for the ITU's IMT-2000 standard and a direct successor to 2G CDMA, IS-95 (CDMA One). CDMA2000 is standardized by 3GPP2. CDMA2000 1X (IS-2000), also known as 1x and 1xRTT, is the core CDMA2000 wireless air interface standard. The designation "1x", meaning 1 times Radio Transmission Technology, indicates the same RF bandwidth as IS-95: a duplex pair of 1.25 MHz radio channels. 1xRTT almost doubles voice capacity over IS-95 networks. Advantages of CDMA2000 CDMA2000 benefited from the extensive experience acquired through several years of operation of cdmaone systems. As a result, CDMA2000 is a very efficient and robust technology. Supporting both voice and data, the standard was devised and tested in various spectrum bands, including the new IMT-2000 allocations. 1. Increased Voice Capacity 2. Higher Data Throughput 3. Frequency Band Flexibility 4. Increased Battery Life 5. Synchronization Key Features of CDMA 2000 1x CDMA 2000 has fundamental requirement to maintain compatibility with IS-95 air interface. This means that IS-95 handsets will continue to work in CDMA 2000 network Page: 2
as well as CDMA 2000 mobiles will work in IS-95 network. This is the key aspect of providing a cost effective solution for 2G operators to gracefully upgrade to 3G networks and completely new network and new mobiles are not required. Faster Forward Power Control: CDMA 2000 1x standard has a faster power control compare to IS-95 counterpart. New Radio Configurations (RC): Provide new digital coding options for improved efficiency over radio channel. It support Radio configuration RC1 to RC9 in Forward Link and RC1 to RC6 in Reverse link. Radio configuration define Rate Set, Spreading Rate, Channel Coding (Turbo or convolutional), channel coding rate, transmit diversity for forward or reverse traffic channel. Efficient use of spectrum: CDMA2000 technologies offer the higher voice capacity and data throughput using the least amount of spectrum, lowering the cost of delivery for operators and delivering superior customer experience for the end users. Seamless Evolution Path: CDMA2000 has a solid and long-term evolution path which is built on the principle of backward and forward compatibility, in-band migration, and support of hybrid network configurations. Flexibility: CDMA2000 systems have been designed for urban as well as remote rural areas for fixed wireless, wireless local loop (WLL), limited mobility and full mobility applications. It also supports R-UIM for open market handsets. System Architecture The CDMA cellular mobile communication system consists of four independent subsystems: Mobile Station (MS), Base Transceiver Subsystem (BSS), Mobile Switching Subsystem (MSS) and Operation & Maintenance Subsystem (OMM). MS and BSS can communicate directly, while the communication between BSS and MSS is implemented through the standard A interface. Other interfaces, such as B, C, D, E, H, M, N, O and P represents the interfaces among the functional entities. When different functional entities are configured in each physical unit, some interfaces will become internal interfaces that may not follow the unified interface standard. Ai, Di and Pi are the system s interfaces to interconnect with other communication networks. Fig. 1 shows the architecture and interfaces of the CDMA system: Page: 3
MS MSC EIR IWF Um E F L PSPDN Pi BTS Abis BSC A MSC Ai PSTN Di Q Q C B ISDN OMC AUC H HLR D VLR N G SME M SME M SC M SC VLR Fig. 1 Network Architecture of the CDMA Cellular Mobile Communications System An Introduction to Network Entities BTS Subsystem The BTS Subsystem (BSS) is the assembly of radio equipment and radio channel control equipment, serving one or more cellular cells. In certain radio coverage, it is controlled by the Mobile Switching Center (MSC) to implement channel assignment, user access and paging, and information transfer. Normally, the BSS consists of one or more BSCs and BTSs. The BTS is responsible for radio transmission and BSC for control and management. Base Transceiver The Base Transceiver (BTS) belongs to the radio part of a basestation system. Controlled by BSC, it serves the radio transceiving equipment of a certain cell, implements the conversion between BSC and radio channels, radio transmission through air interface between BTS and MS and related control, and communicates with BSC through the Abis interface. Page: 4
Base Station Controller One end of the Base Station Controller (BSC) can be connected with one or more BTSs, while its other end can be connected with MSC and OMC. Oriented to radio network, BSC implements radio network management, radio resource management and radio BTS monitoring and management. It also controls the establishment, connection and disconnection of radio connection between MS and BTS, controls the positioning, handoff and paging of MS, provides voice coding and rate adjustment and carries out operation and maintenance of the BSS. Mobile Switching Subsystem The Mobile Switching Subsystem (MSS) implements the main switching functions of the CDMA network. Meanwhile it manages the database for user data and mobility. Mobile Switching Center MSC is the core of the CDMA network. It controls and implements voice channel connection for MSs within its coverage, namely serving as an interface between CDMA and other networks. The functions MSC carries out include call connection, charging, BSS-MSC handoff, assist radio resource management and mobility management. Besides, each MSC also implements the GMSC function for call route establishment to the MS, namely, to query the location information of each MS. MSC gets all data required for call request processing from three databases, VLR, HLR and AUC. Visitor Location Register The Visitor Location Register (VLR) is a dynamic user database, storing the related user data of all MSs (visitors) within the MSC s management range, including user ID, MS s location area information, user status and services available for the user. VLR gets and stores all necessary data from the HLR of a mobile subscriber. Once the mobile subscriber leaves the control area of the VLR, it will be registered in another VLR, and the previous VLR will delete its data log. Home Location Register The Home Location Register (HLR) is a static database, storing the data for mobile subscriber management. Each mobile subscriber should be registered in its HLR. It stores two kinds of information: parameters related with the mobile subscriber, including the subscriber s ID, access capability, user type and supplementary service; current location information of the subscriber for call route establishment. For example: the address of Page: 5
MSC or VLR. No matter where the mobile subscriber roams, its HLR should provide all related parameters and input the latest location into the database. Authentication Center The Authentication Center (AUC), a functional entity managing the authentication information related with mobile stations (MSs). It implements MS authentication, stores the MS authentication parameters, generates and sends the corresponding authentication parameters according to the requests of MSC or VLR, including A-KEY, SSD, ESN, MIN and AAV, and then calculates all random numbers to get the authentication result. The Short Message Center (SC) is responsible for receiving, storing and forwarding short messages between the CDMA mobile subscribers and fixed line users or between mobile subscribers. It serves as a postal office, receiving mails from every place, sorts them out and then distribute them to the corresponding users. Through SC, the messages can be sent to destination more reliably.the short message services include point-to-point server and cell broadcast service. Operation and Maintenance Management Subsystem (OMM) The Operation & Maintenance Center (OMC) provides equipment operators with network operation and maintenance services, manages subscriber information, makes network planning and improves the efficiency and service quality of the whole system. OMC includes OMC-S and OMC-R, depending on the part for maintenance. OMC-S is responsible for the maintenance on the MSS side while OMC-R is responsible for the maintenance on the BSS side. Its specific functions include: maintenance test, obstacle check and handling, system status monitoring, realtime system control, office data modification, performance management, subscriber tracking, alarm and traffic measurement. Interfaces According to the Open System Interconnection (OSI) model, we can analyze the CDMA network on the aspects of interface, protocol and interface functions in detail. Interfaces As shown in Fig. 1, various interfaces exist in the CDMA system. They can divided into the following categories according to different subsystems: Air interface Um between mobile terminals and the BSS, A interface between BSS and MSS, and other interfaces between internal entities of the network. Page: 6
Air interface The Um interface is defined as the communication interface between MS and BTS. It is the key distinguishing the CDMA network from the GSM network and the most important interface of the CDMA network. This interface grants compatibility to MSs from different suppliers and networks of different operators, enables MSs to roam, ensures the frequency efficiency of the cellular system, and adopts a series of anti-interference technologies and interference preventing measures. Obviously, the Um interface implements the physical connection from MS to the fixed part of the CDMA system, i.e. the wireless connection. Besides, it transfers information for radio resource management, mobility management and connection management. Interface between BSS and MSS A interface The A interface is located between MSC and BSC. Its physical link is implemented through standard PCM digital transmission link of 2.048Mbit/s. It transfers information for MS management, BTS management, mobility management and connection management. BSS internal interface (Abis) An interface between BSC and BTS is called the Abis interface. BSC on the Abis interface provides signaling control information for BTS configuration, monitoring, and testing and service control. Please refer to related documentation about the BTS side. MSS internal interfaces BTS BSS BSC A MSC VLR B C C D HLR/AUC E VLR MSC B Q N MC Fig. 3 Internal Interfaces of the Network Page: 7
B interface As an internal interface between VLR and MSC, the B interface is used by the MSC to request the current location information of the MS from VLR or notify the VLR to update the location information of the MS. C interface As an interface between HLR and MSC, the C interface transfers information for route selection and management. Once a call is required to a MS, the Gateway MSC (GMSC) will request the roaming number of the called MS from the HLR of the called side. The physical link of the C interface is 2.048Mbit/s standard PCM digital transmission cable. D interface As an interface between HLR and VLR, the D interface exchanges information related with MS location and user management. It ensures that the MS can establish and receives calls within the entire service area. Its physical link is 2.048Mbit/s standard digital link. E interface It is the interface controlling different MSCs of adjacent areas. When the MS moves, during a call, from the control area of one MSC to that of another MSC, this interface can be used to exchange related handoff information to activate and complete handoff, and thus to complete the cross-cell channel handoff process without interrupting the communication. Its physical link is implemented through 2.048Mbit/s standard digital link between MSCs. N interface This interface is used to transfer route information related with the called subscriber between MC and HLR. Its physical link is implemented through 2.048Mbit/s standard digital link. Q interface It is an interface between MS and MSC transferring short messages. Page: 8
Chapter 5.-Overview of CDMA 2000 1x Sample Self study questions 1. CDMA stands for 2. is a static database 3. is the core CDMA2000 wireless air interface standard. 4. Designation "1x", means 5. is responsible for receiving, storing and forwarding short messages between the CDMA mobile subscribers and fixed line users or between mobile subscribers. 6. is a dynamic database 7. An interface between BSC and BTS is called the 8. is defined as the communication interface between MS and BTS 9. 2G CDMA standards are named as CDMAone includes 10. LAI is stored in Subjective Questions 1. What are the advantage of CDMA 2000 2. Explain the functions of BSC 3. Explain the function of MSC 4. Draw the block schematic of CDMA 2000 1x Network Architecture with all system components and Interfaces? Page: 9