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Differentiate between the Base Station Subsystem (BSS) and Network Switching Subsystem (NSS).

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The Base Station Subsystem (BSS) and Network Switching Subsystem (NSS) are two key components in GSM (Global System for Mobile Communications) networks, each serving distinct functions in the overall architecture. Here's a detailed technical differentiation between the Base Station Subsystem (BSS) and Network Switching Subsystem (NSS):

Base Station Subsystem (BSS):

  1. Function:
    • BSS: The BSS is primarily responsible for managing the radio communication between the Mobile Station (MS) and the network. It includes Base Transceiver Stations (BTS) and Base Station Controllers (BSC).
  2. Components:
    • BTS (Base Transceiver Station): The BTS is responsible for the radio transmission and reception of signals to and from the MS. It manages the air interface, including modulation, coding, and radio frequency (RF) functions.
    • BSC (Base Station Controller): The BSC controls multiple BTS units. It manages handovers, frequency hopping, and other radio resource allocation functions. The BSC also interfaces with the Mobile Switching Center (MSC) for call establishment and release.
  3. Radio Resource Management:
    • BSS: The BSS is primarily focused on managing radio resources, including frequency channels, power levels, and handovers, to ensure efficient communication between the MS and the network.
  4. Cell Management:
    • BSS: Manages the configuration and operation of individual cells within the network. This includes setting parameters for cell coverage, handover thresholds, and cell-specific parameters.
  5. Air Interface Protocols:
    • BSS: Implements air interface protocols for communication between the MS and the network. This includes protocols for channel access, modulation schemes, and error correction.
  6. Frequency Planning:
    • BSS: Involves planning the allocation of frequency channels to different cells to avoid interference and optimize spectrum utilization.

Network Switching Subsystem (NSS):

  1. Function:
    • NSS: The NSS is responsible for managing call switching, mobility management, and subscriber-related functions within the GSM network. It includes the Mobile Switching Center (MSC), Visitor Location Register (VLR), and Home Location Register (HLR).
  2. Components:
    • MSC (Mobile Switching Center): The MSC is the central switching entity in the GSM network. It handles call routing, switching, and signaling between mobile subscribers and external networks.
    • VLR (Visitor Location Register): The VLR temporarily stores subscriber information when they are outside their home network's coverage area. It facilitates call setup and handover procedures.
    • HLR (Home Location Register): The HLR is the centralized database that stores permanent subscriber information, including subscriber profiles, service subscriptions, and authentication keys.
  3. Call Routing and Switching:
    • NSS: Manages the routing and switching of voice and data calls within the network. The MSC is responsible for establishing connections, handling handovers, and ensuring the delivery of calls.
  4. Subscriber Management:
    • NSS: Manages subscriber-related functions, including subscriber registration, authentication, and updating subscriber information. The HLR serves as the central repository for subscriber profiles.
  5. Mobility Management:
    • NSS: Handles mobility-related functions, including tracking the location of subscribers, updating location information in the VLR, and facilitating handovers between different cells or networks.
  6. Signaling and Control:
    • NSS: Manages signaling and control functions for call setup, teardown, and handovers. It uses protocols such as Signaling System No. 7 (SS7) for communication between network elements.
  7. Billing and Charging:
    • NSS: Captures information related to call duration, service usage, and other billing-related data. This information is crucial for billing and charging subscribers for network services.
  8. Network Interconnection:
    • NSS: Facilitates the interconnection of the GSM network with external networks, including other GSM networks, PSTN (Public Switched Telephone Network), and data networks.

In summary, the Base Station Subsystem (BSS) is primarily concerned with managing radio resources and air interface communication, while the Network Switching Subsystem (NSS) focuses on call switching, mobility management, and subscriber-related functions within the GSM network. The BSS and NSS work in coordination to provide comprehensive mobile communication services.