Sign in Subscribe

2g cellular network

Last updated on 


Certainly! Let's delve into the technical details of a 2G (Second Generation) cellular network. The following explanation focuses on the GSM (Global System for Mobile Communications) standard, which is one of the most widely used 2G technologies.

1. GSM Architecture:

a. Mobile Station (MS):

  • Mobile Device: The MS represents the mobile device, such as a feature phone, that a user uses to make calls and access mobile services.

b. Base Station Subsystem (BSS):

  • Base Transceiver Station (BTS):
    • Manages the radio communication with mobile devices within its coverage area.
    • Transmits and receives voice and data signals.
  • Base Station Controller (BSC):
    • Manages multiple BTS units.
    • Responsible for handovers, frequency hopping, and resource allocation.

2. Network Components:

a. Mobile Switching Center (MSC):

  • Switching Function:
    • Manages call setup, release, and handovers.
    • Responsible for routing calls between mobile users and to external networks.
  • Home Location Register (HLR):
    • Database storing subscriber information, including user profiles, subscription details, and current location.
  • Visitor Location Register (VLR):
    • Temporarily stores information about subscribers currently within the jurisdiction of the MSC.

3. Network Architecture:

a. Circuit-Switched Network:

  • Voice Calls:
    • 2G networks are primarily designed for circuit-switched voice calls.
    • Dedicated communication path established for the duration of the call.

b. Channel Allocation:

  • Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA):
    • FDMA divides the frequency spectrum into channels.
    • TDMA further divides each channel into time slots, allowing multiple users to share the same frequency.

c. GSM Channels:

  • Traffic Channels (TCH):
    • Used for carrying voice and user data during active calls.
  • Control Channels:
    • Broadcast Control Channel (BCCH): Carries information about the cell.
    • Common Control Channel (CCCH): Used for signaling and system control.

4. Modulation and Coding:

a. Modulation Techniques:

  • Gaussian Minimum Shift Keying (GMSK):
    • Modulation scheme used in GSM for radio transmission.
    • Ensures signal integrity in the presence of noise.

b. Error Correction:

  • Convolutional Coding:
    • Used for error correction in the transmission of voice and data.

5. Data Services:

a. General Packet Radio Service (GPRS):

  • Packet-Switched Data:
    • Introduced for basic data services.
    • Allows for more efficient use of network resources.

6. Security:

a. Authentication and Encryption:

  • Subscriber Identity Module (SIM):
    • Contains subscriber-specific information.
    • Used for authentication and encryption of communication.

b. A5 Encryption Algorithm:

  • Used to Secure Voice Calls:
    • Ensures privacy and security of voice communication.

7. Handovers:

a. Intra-BSC Handover:

  • Within the Same BSC:
    • Handover between different BTS units controlled by the same BSC.

b. Inter-BSC Handover:

  • Between Different BSCs:
    • Handover involving BTS units controlled by different BSCs.

8. Evolution and Migration:

a. Migration to 3G and Beyond:

  • Introduction of 3G Technologies:
    • 2G networks provided the foundation for the subsequent introduction of 3G and beyond.
    • Allowed for higher data rates, multimedia services, and improved network capabilities.

In summary, a 2G cellular network, particularly based on the GSM standard, is characterized by its circuit-switched architecture, channel allocation using FDMA and TDMA, modulation techniques like GMSK, and the provision of basic voice and data services. The network components, including the MSC, BSS, HLR, and VLR, work together to provide seamless communication for mobile subscribers. Over time, advancements in mobile technologies led to the evolution of networks beyond 2G, but the foundational principles of 2G networks continue to influence mobile communication standards.