电信常识

电信常识

1. 目前的移动世界是传统语音电话的延伸，与每一个PSTN一样，每个PLMN都有一个TDM语音电路层（传送层）和一个信令层（控制层SS7）;2.5G 增加了IP数据连接，语音电话丝毫不受影响；

2.  电信业的发展：
  1) FDMA 频分多路 - Frequency Division Multiple Access (1920s - )
        . radio broadcasting
        . 1st generation mobile system(NMT, TACS, ...)
   2) TDMA 时分多路 - Time Division Multiple Access (1980-)
        . 2nd generation mobile systems: GSM, US-TDMA, PDC
        . narrowband systems
   3) CDMA 码分多路 - Code Division Multiple Access (late 1990s - )
        . 3rd generation mobile systems: WCDMA, CDMA2000

国际上的电信标准化组织
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CWTS - China Wirelss Telecommunication Standard Group
ETSI   - European Telecommunication Standard Institute
GSM   - Global System for Mobile Communication
IETF   - Internet Engineering Task Force
ITU-T - International Telecommunication Union - Telecommunication Standardization

1. 3GPP/3GPP2、IETS的分工：
  1) 3GPP is responsible for system architecture standardisation for GSM/WCDMA
  2) 3GPP2 is standardising cdma2000 evolution
  3) IETF protocols to be used as applicable in 3GPP systems

2. 3GPP
 1) Release 99 (2000,3) - Major RAN release
  New radio interface - WCDMA
  New RAN architecture - soft handover
  New CN-AN interface(transcoder in CN, SGSN functions to RNC)
  Open Service Architecture for Services
  GSM-UMTS interworking
 
 2) Release 4 (2001,3) - Minor release
  UTRAN access with some QoS enhancements
  CS Domain Evolution, MSC Servers and MGWs, based on IP protocols
  IP transport of CN protocols
  IP Header compression(IETF)
  Locationi Services enhancements, MMS, WAP, MExE, Streaming
 
 3) Rlease 5(2002,3) - Major core ntw release
  IP Multimedia Services Subsystem - Basic communications platform
   - SIP signalling, registration, session initiation, IMS SIM, IMS security architecture
   - Usage of IETF protocols, e.g., IPv6, SIP, Diameter
   - SIP-based service environment
   - QoS for IMS: SIP Compression, QoS authorization and policy control
  GERAN alignment with UMTS
  WCDMA enhancements (e.g. HSDPA, IP transport)
  MMS enhancements, LCS enhancements
 
 4) Release 6 (2003,12) - IMS Part II
  IMS Phase 2
   - Release 5 left-over items(regulatory requirements, circuit-switched interworking, service based local policy enhancements, etc)
   - optimised voice communications
   - Presence, Instance Messaging, Group Management and Conferencing
  New Work Items:
   - 3GPP/3GPP2 IMS harmonisation (incl. access independency), UMTS-WLAN interworking, Multimedia Broadcast/Multimedia Service, etc