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  • A CDMA system includes four independent subsystems: mobile station (MS), base station subsystem (BSS) and mobile switching subsystem (MSS). OMM
  • BSS is a general term for wireless equipment and wireless channels control equipment serving one or several cells. Usually, BSS consists of one or more Base Station Controllers (BSC) and Base Transceiver Stations (BTS).
  • AS the central part of cdma system, MSC serves to control the mobile stations that are within its controlling sphere, and to perform the channel switching. It functions as the interface between the mobile system and the other public telecommunication means. MSC provides the network interfaces, the charging function and the function of processing the common channel signaling. It can process the No. 7 signaling between BSS and MSC, and realizes the auxiliary radio resource management and mobile management. In addition, for the sake of establishing the calling route to the mobile station, each MSC can function as a Gateway MSC (GMSC). If a network transfers a call to PLMN, but if it cannot query HLR, then the call will route to a MSC. This MSC will query related HLR, and rout the call to the MSC where the called subscriber is located. This kind of MSC is called a gateway MSC (GMSC). Which MSCs are to be chosen as GMSC depends on the network service carrier.
  • The VLR is a location register used by MSC for information index. It saves and updates data of mobile subscribers who roam to this VLR service area. VLR can be built together with the MSC or set separately, in the former case, interface B turns to be an internal interface.
  • The HLR is a location register used for registering identity of subscribers, including subscriber information (ESN, MDN, IMSI, MIN), service information, current location and valid term, etc. HLR can be built together with the MSC or set separately. In case of the former, interface C turns to be an internal interface.
  • Authentication center is a functional entity for the management of authentication information related to the mobile stations. It functions to authenticate mobile subscribers, save authentication parameters of mobile subscribers and generate and send corresponding authentication parameters in response to the request from MSC/VLR. AUC can be built together with HLR or set separately. In case of the former, interface H turns to be an internal interface.
  • 操作维护中心( OMC ) 用于对 GSM 系统的交换实体进行管理。实现以下功能: 1 、维护测 试 2 、障碍检测及处理 3 、系统状态监视、 4 、系统实时控制 5 、局数据修改 6 、性能管理 7 、用户跟踪、告警 8 、话务统计等 按功能分为几大模块,模块又分为前后台,

Transcript

  • 1. ZTE Basic knowledge of CDMA MSC Based WLL (BSNL) Compiled by: M.Pandian, Divisional Engineer CDOT Installation, Salem-1 E-Mail: cdotpandian@rediffmail.com
  • 2. Advantages of CDMA
    • Frequency reuse
    • Large coverage
    • High spectrum capacity
    • High Privacy
    • Soft Handoff
    • Good Voice quality (using Voice Coding)
    • Perfect Power Control
    • Smooth migration to 3G
  • 3. Advantages of CDMA Frequency reuse facto is 1; network design and expanding become much easier AMPS , D-AMPS , N-AMPS CDMA 30 30 10 kHz 200 kHz 1250 kHz 1 3 1 Users 8 Users 20 Users 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 3 4 4 3 2 5 6 1 7 Typical Frequency Reuse N=7 Typical Frequency Reuse N=4 Typical Frequency Reuse N=1 Vulnerability: C/I  17 dB Vulnerability: C/I  12-14 dB Vulnerability: E b /N o  6--7 dB GSM
  • 4. Advantages of CDMA large coverage almost 2 times than GSM, save money for operator Example:cover 1000 km 2 : GSM need 200 BTS , CDMA only need 50 BTS Attention: exact result need “ Link Budget ”
  • 5. Advantages of CDMA High spectrum capacity: 8--10 times than AMPS, 4—6 times than GSM FDMA---Different user use different frequency TACS 、 AMPS TDMA---Different user use different time slot of one frequency GSM 、 DAMPS CDMA---Different user use same frequency at the same time,but with different spreading code Frequency Time Power Frequency Time Power Frequency Time Power FDMA TDMA CDMA
  • 6. Advantages of CDMA
    • High privacy,hard to wiretapping
    Spread code Information signal TX Demodulated signal RX Spread code Spread signal Each user is below the noise deeply
  • 7. Advantages of CDMA
    • CDMA: “make before break”---soft handoff
    • Other systems: “make after break”---hard handoff
    Use soft handoff, decrease drop-call rate
  • 8. Advantages of CDMA Good voice quality, use 8k,13K(QCELP,EVRC)voice coding—the best coding method in the world. Voice quality (MOS) 64k PCM 13k GSM 8k CDMA 13k CDMA 8kEVRC CDMA
  • 9. Advantages of CDMA Perfect Power Control and voice activation make the MS Power low, healthy for humanbody—green mobile phone. Mean Power Max Power GSM: 125mW 2W CDMA: 2mW 200mW
  • 10. Advantages of CDMA
    • 95A  95B
    • Software update
    • Replace MS to
    • get new service
    • 95B  1X
    • Add 1X channel
    • board
    • Software update
    • Replace MS to ge
    • new service
    • 1X  1XEV
    • Add 1XEV channel board
    • Software update
    • Replace MS to
    • get new service
    • inexpensive
    Technical Scheme: Smooth migration to 3G and the operator’s benefit is protected at the most
    • Almost free
    • inexpensive
    Economic Scheme:
  • 11. ZTE’s Activities in CDMA
    • In 1995, CDMA mobile telecommunication project was started
    • In November, 1999, ZTE signed the “Agreement on CDMA R&D” with Qualcomm
    • In August, 2000, the first field trial was set up.
    • In September, 2000, ZTE presented the first CDMA handset with UIM in the world.
    • In January, 2001, the first cdma2000-1x call was passed through in lab
    • In March, 2001, ZTE cdma2000-1x realized the integrated transmission of voice, data & image. The data rate reach up to 153.6Kbps.
    • The certificates acquired:
      • CDMA 800M ZXC10-MSC/VLR, HLR/AUC,BSC, BTS network access licenses
      • CDMA 800M/1.9G ZXC10-BTS type approval certificates
  • 12. ZTE - CDMA 2G/3G 终端 Abis Abis Abis PSTN/PLMN BSC/ PCF (1X) Internet 路由器 路由器 IP IP BTS ( IS-95 ) BSC ( IS-95 ) Abis E1 Um IS95 Um IS2000 E1 STM-1 E1 STM-1 Ethernet MSC/VLR HLR/AUC PDSN/FA AAA HA OMC SC WIN BTS ( IS-95 ) BSC/ PCF (1X) BTS ( 1X ) BTS ( 1X ) E1 业务服务器 Ethernet
  • 13. ZXC10 MSC / VLR
    • ZXC10 MSC/VLR/SSP 1X stands for The CDMA mobile switching center/visitor location register product.
    • MSC is a functional entity that performs the controlling and switching of mobile subscribers within the area it serves, and it is automatic switching equipment for the traffic between MSCs or between MSC of CDMA network and switches of other public networks.
  • 14. ZXC10 MSC / VLR
    • MSC performs the common signaling function and billing function, and offers network interfaces.
    • It performs the management of signaling system, wireless resource and A interface signaling between BSS and MSC.
    • It also sets up the calling route for the called mobile subscribers if the function of GMSC has been integrated.
  • 15. ZXC10 MSC / VLR
    • VLR is a database and responsible for the storage and updating of data of mobile subscribers that roam to the service area of this VLR.
    • The information includes user number, property, and location identification and service parameters.
  • 16. Technical specifications
    • MSC system capacity: 600,000
    • Max Number of subscribers: 600,000 (64K*64K)
    • Call Processing Capacity for Single Module: 500K BHCA
    • Max Call Processing Capacity: 5,000K BHCA
    • Max Traffic: 21,000Erl
    • Max Number of No.7 signaling links: 640 links
    • VLR System Capacity: 800,000
  • 17. Architecture of CDMA system Um E Abis A Q C B N N MS BT S B S C PSTN M S C M S C/SSP VLR HLR AUC MC D MC M MSS BSS Ai
  • 18.
    • MS: Mobile Station
    • BSC: Base Station Controller
    • BTS: Base Transceiver Station
    • MSC: Mobile Switching Center
    • VLR: Visitor Location Register
    • HLR: Home Location Register
    • AUC: Authentication Center
    • OMC: Operation and Maintenance Center
    • MC: Message Center
    Architecture of CDMA system
  • 19. Other Terminologies used
    • PLMN: Public Land Mobile Network
    • ESN: Electronic Serial Number
    • MIN: Mobile Station Identification Number
    • IMSI: International Mobile Subscriber Identification
    • MSIN: Mobile Station Identification Number
    • MCC: Mobile Country Code
    • MNC: Mobile Network Code
    • SID: System Identification
    • NID: Network Identification
  • 20. Main components of CDMA
    • MSS (Mobile Switching Sub-system)
    • BSS (Base Station Sub-system)
    • MS (Mobile Station)
    • OMC (Operation and Maintenance Center)
    Architecture of CDMA system
  • 21. 1. Base Station Sub-system
    • Function: It provides trunks between wireless part and fixed part of PLMN network.
    ---BSC BSC performs the controlling function and management. ---BTS BTS is in charge of wireless transmission . Architecture of CDMA system
  • 22.
    • Function:
    • CDMA switching function
    • Manage mobile subscriber data
    • Manage database for mobile service
    • Interface between CDMA network and other network (such as PSTN, other PLMN etc.).
    • It includes 4 function units:
        • ---MSC ---VLR
        • ---HLR ---AUC
    2. Mobile Switching Sub-system Architecture of CDMA system
  • 23.
      • It is responsible for setting up, managing and clearing connections as well as routing the calls to the proper user.
      • It provides the network interfaces, the charging function and the function of processing the signaling.
      • MSC get data for call handling from 3 databases: VLR/HLR/AUC
    Architecture of CDMA system
        • 1) Mobile Switching Center(MSC)
  • 24.
    • Visitor Location Register(VLR)
    • VLR is a dynamic database used by MSC for information index. It stores all related information of mobile subscribers that enter its coverage area, which enables MSC to set up incoming and outgoing calls.
    • Subscriber parameters include: subscriber number, location area identity(LAI), user’s status, services which subscriber can use and so on.
    • When the subscriber leaves this area, it should register in another VLR, and the previous VLR will delete all the data about this subscriber.
    • VLR can be built together with the MSC or set separately
    Architecture of CDMA system
  • 25.
    • HLR: It is a static database. When a user apply for mobile service, all data about this subscriber will be stored in HLR.
    • Information:
    • ----Subscriber information (ESN, MDN, IMSI, MIN), service information and valid term.
    • ----The mobile subscriber location (MSC/VLR address), so as to set up the call route to the MS.
    • • HLR can be built together with the MSC or set separately.
    3) Home Location Register (HLR) Architecture of CDMA system
  • 26. 4) Authentication Center
    • • Conception: It is an entity to prevent illegal subscribers from accessing CDMA network. It can generate the parameter to confirm the subscriber’s identity. At the same time it can encrypt user’s data according to user’s request.
    • • Composition:
    • Database: save MIN,ESN, authentication key)
    • Generator of random number
    • Algorithm(CAVE algorithm)
    • AUC can be built separately or together with HLR
    Architecture of CDMA system
  • 27. Operation and Maintenance Center (OMC) OMC provides operation and maintenance services to the network operator, manages the registered subscriber information and conducts network planning to enhance the overall working efficiency and service quality of the system. Based on the main maintenance functions, there are two types of operation and maintenance centers: OMC-S and OMC-R . The OMC-S is mainly responsible for maintenance of MSS while the OMC-R is mainly for BSS. We also call OMC as background . Architecture of CDMA system
  • 28. ZXC10 BSC
  • 29. ZXC10 BSC-FEATURES
    • Two layer high rate packet network structure based on ATM technology
    • Circuit-supporting data service such as asynchronous data, G3 fax.
    • Supporting various types of voice conversion algorithm: QCELP (IS-95), 13kbps Pure Voice (IS-733), EVRC (IS-127) and echo cancellation.
    • Built-in PCF, which supports high rate packet data service primarily based on mobile IP
    • Providing E1/STM-1, which supports A3 and A7 interfaces defined by IOS4.0 and implements the interconnection of BSCs.
    • Providing E1/STM-1, which supports A1, A2 and A5 interfaces defined by IOS4.0 and implements the interconnection of MSCs.
    • Providing Fast Ethernet/ATM., which supports A10 and A11 interfaces defined by IOS4.0 and implements the interconnection of PDSNs.
  • 30. The basic performances of ZXC10 BSC
    • Each BSC owns a HIRS network providing 256 high rate serial ports. Each serial port affords 10Mbps transmission capacity.
    • Each BSC/PCF provides 240 E1 links with MSC maximum.
    • Each BSC/PCF provides 380 E1 inks with BTSs maximum.
    • Each BSC/PCF supports 7200-selectors/ vocoders maximum.
    • Each BSC/PCF has the maximum traffic processing capacity of 5040 Erl.
    • Each BSC/PCF processes 170,000 voice users maximum (based on 0.03Erl/sub)
    • Each BSC/PCF can connect with 380 BTSs (single carrier/single sector) maximum.
    • The BSC/PCF supports packet data services. Each Supports 1260 active PPP connections and 24,000 dormant PPP connections.
  • 31. ZXC10 BTS
  • 32. The basic performances-BTS
      • RAKE receiving, diversity sending, and smart antenna
      • Softer handoff between sectors, soft handoff, and hard handoff
      • Cell breathing, blossoming, wilting, and TPTL
      • High efficient wireless resource management
      • Hot standby for key components
      • Automatic and periodical performance test to ensure reliability
      • All boards can be hot swapped, supporting on line maintenance
      • Module function is relatively independent. Single rack of BTS can accomplish 1,2,3 and 4 carriers, supporting Omni-, 2-sector, 3-sector and 6-sector cell. Supporting capacity expansion in stacking method
  • 33. The basic performances-BTS
    • Supporting 128 forward channels among which 55 channels are traffic channels with data rate of 9.6kbps (Practically 40 x 3 = 120 traffic channels per ‘3sector’ BTS is possible.)
    • All the channel units in a rack form a sharing pool
    • Providing optic fiber interface between base band digital subsystem and radio frequency subsystem.
    • Base station supports indoor modules, outdoor modules and remote RF modules in various packing styles
    • Supporting two types of clock systems: GPS and GLONASS Simultaneously
    • Supporting voice services and mobile IP-based high rate packet data services
    • Providing E1 or STM-1 links between BTS and BSC according to the capacity of BTS
  • 34. BDS: Base band Digital Subsystem
    • CHM: Channel Processing Module
    • CCM: Communication Control Module
    • RFIM: RF Interface Module
    • SAM: Site alarm module
    • BTS_CDSU: BTS-side CDSU module
  • 35. TFS:Timing Frequency Subsystem
    • GPSTM:GPS Timing Module
    • FDM: Frequency Distribution Module
    • TCM: Timing Control Module
  • 36. RFS:RF Subsystem
    • TRX: RF Transceiver
    • HPA: High Power Amplifier
    • RFE: RF Front End
    • RFCM: RF Control Module
    • BTM: Base station testing module
  • 37. CDMA Forward Traffic Channels
    • Used for the transmission of user and signaling information to a specific mobile station during a call.
    • Maximum number of traffic channels: 64 minus one Pilot channel, one Sync channel, and 7 Paging channel.
    • This leaves each CDMA frequency with at least 55 traffic channels.
    • Unused paging channels can provide up to 6 additional channels.
    Forward Traffic Channel Forward Traffic Channel Sync Paging Forward Traffic Channel Forward Traffic Channel Pilot  CDMA Cell Site
  • 38. Pilot Channel
    • Used by the mobile station for initial system acquisition
    • Transmitted constantly by the base station
    • The same Short PN sequences are shared by all base stations
      • Each base station is differentiated by a phase offset
    • Provides tracking of:
      • Timing reference
      • Phase reference
    • Separation by phase provides for extremely high reuse within one CDMA channel frequency
    • Acquisition by mobile stations is enhanced by:
      • Short duration of Pilot PN sequence
      • Uncoded nature of pilot signal
    • Facilitates mobile station-assisted handoffs
      • Used to identify handoff candidates
      • Key factor in performing soft handoffs
  • 39. Sync Message Parameters
    • Message Type (MSG_TYPE) – Identifies this message and determines its structure (set to the fixed value of ‘00000001’)
    • Protocol Revision Level (P_REV) – Shall be set to ‘00000001’
    • Minimum Protocol Revision Level (MIN_P_REV ) – 8-bit unsigned integer identifying the minimum protocol revision level required to operate on the system. Only mobile stations that support revision numbers greater than or equal to this field can access the system.
    • System ID (SID) – 16-bit unsigned integer identifying the system
    • Network ID (NID) – 16-bit unsigned integer identifying the network within the system (defined by the owner of the SID)
    • Pilot PN Sequence Offset Index (PILOT_PN ) – Set to the pilot PN offset for the base station (in units of 64 chips), assigned by the network planner
    • Long Code State (LC_STATE) – Provides the mobile station with the base station long code state at the time given by the SYS_TIME field, generated dynamically
    • System Time (SYS_TIME) – GPS system-wide time as 320 ms after the end of the last superframe containing any part of this message, minus the pilot PN offset, in units of 80 ms, generated dynamically
  • 40. Sync Channel Message (cont.)
    • Leap Seconds (LP_SEC) – Number of leap seconds that have occurred since the start of system time (January 6, 1980 at 00:00:00 hours) as given in the SYS_TIME field, generated dynamically
    • Local Time Offset (LTM_OFF) – Two’s complement offset of local time from system time in units of 30 minutes, generated dynamically
      • Current local = SYS_TIME – LP_SEC + LTM_OFF
    • Daylight savings time indicator (DAYLT) – Determined by the network planner
      • 1 if daylight savings in effect in this base station
      • 0 otherwise
    • Paging Channel Data Rate (PRAT) – The data rate of the paging channel for this system, determined by the network planner
      • 00 if 9600 bps
      • 01 if 4800 bps
    • CDMA Frequency Assignment (CDMA_FREQ)
  • 41. Paging Channels
    • There is one paging channel per sector per CDMA carrier
    • The Paging Channel uses Walsh function 1
    • Two rates are supported: 9600 and 4800 bps
    Paging Channel Used by the base station to transmit system overhead information and mobile station-specific messages.
  • 42. CDMA Reverse Traffic Channels
    • Used when a call is in progress to send:
    • Voice traffic from the subscriber
      • Response to commands/queries from the base station
      • Requests to the base station
    • Supports variable data rate operation for:
      • 8 Kbps vocoder
        • Rate Set 1 - 9600, 4800, 2400 and 1200 bps
      • 13 Kbps vocoder
        • Rate Set 2 - 14400, 7200, 3600, 1800 bps
    Reverse Traffic Channel
  • 43. Access Channels
    • Used by the mobile station to:
      • Initiate communication with the base station
      • Respond to Paging Channel messages
    • Has a fixed data rate of 4800 bps
    • Each Access Channel is associated with only one Paging Channel
    • Up to 32 access channels (0-31) are supported per Paging Channel
    4800 bps
  • 44. CDMA MS Call Processing Power-Up Initialization Idle System Access Traffic Mobile station has fully acquired system timing Mobile station receives a Paging Channel message requiring ACK or response, originates a call, or performs registration Mobile station is directed to a Traffic Channel Mobile station ends use of the Traffic Channel Mobile station receives an ACK to an Access Channel transmission other than an Origination Message or a Page Response Message Mobile station is in idle handoff with NGHBR_CONFG equal to ‘011’ or is unable to receive Paging Channel Message
  • 45. Field Problems
    • ZTE Instruments reading the Primary Channel 42 and 83 in the same instrument; example felt at Namakkal and Attur.
    • Cell Demarcation: Subscriber of one SDCA has to work in the BTS located in the other SDCA with the dominated signal. Example at Kandhampayam and Puduchathiram. This has been experimented at Madurai MSC and to be tried at Pondichery MSC also.
  • 46.
    • Thanks for listening
    • Contact me at
    • 9443200325
    • 04272452266