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WCDMA Network Architecture

WCDMA Network Architecture

The Wideband Code Division Multiple Access (WCDMA) network architecture:

1. User Equipment (UE):

  • The UE, often a mobile phone or data card, is the device used by the end-user to access the WCDMA network.

2. UMTS Terrestrial Radio Access Network (UTRAN):

  • UTRAN is the radio access network in WCDMA, consisting of NodeB (base stations) and Radio Network Controllers (RNCs).
  • NodeB: Responsible for radio transmission and reception. It connects to the UE and handles radio resource management.
  • Radio Network Controller (RNC): Manages resources, handovers, and controls multiple NodeBs.

3. Core Network (CN):

  • The Core Network handles the overall network operations, including user authentication, mobility management, and connectivity to external networks. It consists of several key elements:

    a. Mobile Switching Center (MSC): Controls calls and manages mobility functions.

    b. Serving GPRS Support Node (SGSN): Manages packet-switched data services and user mobility within the network.

    c. Gateway GPRS Support Node (GGSN): Connects the WCDMA network to external packet-switched networks, like the internet.

4. Home Location Register (HLR) and Visitor Location Register (VLR):

  • HLR stores subscriber information and manages user profiles.
  • VLR stores temporary information about subscribers who are currently in the served location area.

5. Mobile Switching System (MSS):

  • The MSS includes MSC and associated functionalities.

6. Mobile Data Management (MDM):

  • MDM manages mobility for packet-switched services.

7. WCDMA Channels:

  • WCDMA uses different channels for communication, including Traffic channels (carrying user data), Control channels (for signaling and control information), and Broadcast channels (for system information).

8. Interfaces:

  • Various interfaces exist between network elements to facilitate communication. Examples include the Iub interface between NodeB and RNC and the Iu interface between RNC and Core Network.

  • WCDMA including the RAN (Radio Access Network) and the CN (Core Network). The RAN is used to process all the radio-related functions, while the CN is used to process all voice calls and data connections within the UMTS system, and implements the function of external network switching and routing.
  • Logically, the CN is divided into the CS (Circuit Switched) Domain and the PS (Packet Switched) Domain. UTRAN, CN and UE (User Equipment) together constitute the whole UMTS system
  • A RNS is composed of one RNC and one or several Node Bs. The Iu interface is used between RNC and CN while the Iub interface is adopted between RNC and Node B. Within UTRAN, RNCs connect with one another through the Iur interface.
  • The Iur interface can connect RNCs via the direct physical connections among them or connect them through the transport network. RNC is used to allocate and control the radio resources of the connected or related Node B. However, Node B serves to convert the data flows between the Iub interface and the Uu interface, and at the same time, it also participates in part of radio resource management.
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