• Formulated by the European standardization organization 3GPP, the core network
    evolves on the basis of GSM/GPRS and can thus be compatible with the existing
    GSM/GPRS networks. It can be based on the TDM, ATM and IP technologies to
    evolve towards the all-IP network architecture. Based on the ATM technology, the
    UTRAN uniformly processes voice and packet services and evolves towards the IP
    network architecture. 
  • The cdma2000 system is a 3G standard put forward on the basis of the IS-95
    standard. Its standardization work is currently undertaken by 3GPP2. Circuit Switched
    (CS) domain is adapted from the 2G IS95 CDMA network, Packet Switched (PS)
    domain is A packet network based on the Mobile IP technology. Radio Access
    Network (RAN) is based on the ATM switch platform, it provides abundant adaptation
    layer interfaces. 
  • The TD-SCDMA standard is put forward by the Chinese Wireless Telecommunication
    Standard (CWTS) Group and now it has been merged into the specifications related
    to the WCDMA-TDD of 3GPP. The core network evolves on the basis of GSM/GPRS.
    The air interface adopts the TD-SCDMA mode.