UMTS/3G Architecture

 The UMTS network can be broadly divided into-

  • User Equipment(UE)
  • Radio Network Subsystem(RNS)
  • Core Network(CN)
UMTS/3G Architecture
  1. User Equipment(UE) :
  • USIM(Universal Subscriber Identity Module) :Same as SIM card, But in case of UMTS it is termed as USIM.
  • ME(Mobile Equipment) :Hardware used by subscriber containing IMEI.
      2.Radio Network Subsystem(RNS) :Also known as UMTS Radio Access Network,(UTRAN).It            provides and  manage the air interface for the overall network.
  • Node B : Node B corresponds to BTS in GSM.
  • RNC(Radio Network Controller) :It controls Node B in 3G telecom system.
      3.Core Network(CN) :
  1. Circuit Switch Domain :A permanent channel for the duration of the call.
  • MSC(Mobile Switching Centre) :it manage the circuit switched calls under way.
  • GMSC(Gateway Mobile Switching Centre) :Responsible for obtaining the location of subscriber, so that calls from other external networks can be delivered correctly. In practice, the GMSC is just a function that can be part of a MSC.
      2.Packet Switch Domain :This Domain was designed to carry packet data.

       i>SGSN(Serving GPRS Support Node) :The SGSN provided a number of functions within the                   UMTS network architecture.
  • Mobility management   When a UE attached to the Packet Switched domain of the UMTS Core Network, the SGSN generates MM information based on the mobile's current location.
  • Session management:   The SGSN managed the data sessions providing the required quality of service and it also managed what were termed the PDP (Packet data Protocol) contexts, i.e. the pipes over which the data was sent.
  • Interaction with other areas of the network:   The SGSN was able to manage its elements within the network only by communicating with other areas of the network, e.g. MSC and other circuit switched areas.
  • Billing:   The SGSN was also responsible billing. It achieved this by monitoring the flow of user data across the GPRS network. CDRs (Call Detail Records) were generated by the SGSN before being transferred to the charging entities (Charging Gateway Function, CGF).
        ii>GGSN(Gateway GPRS Support Node) :It handled inter-working between the UMTS packet switched network and external packet switched networks, and could be considered as a very sophisticated router. In operation, when the GGSN received data addressed to a specific user, it checked if the user was active and then forwarded the data to the SGSN serving the particular UE.
    

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