Explain the process of network handoff in mobile communication.

Network handoff, also known as handover, is a crucial process in mobile communication that allows a mobile device to seamlessly transition from one cell or network to another without interrupting ongoing communication. This is particularly important in scenarios where a mobile device is moving between different cells, such as when a user is driving or walking.

The process of network handoff involves several steps and requires coordination between the mobile device, the current serving cell, and the target cell.

Here's a detailed technical explanation of the network handoff process:

  1. Measurement and Signal Strength Monitoring:
    • The mobile device continuously monitors the signal strength and quality of the current serving cell.
    • It also scans neighboring cells to measure their signal strength and quality.
  2. Threshold Crossing:
    • The mobile device has predefined thresholds for signal strength or quality for both the serving cell and neighboring cells.
    • When the signal strength or quality of the current serving cell falls below a certain threshold, or when a neighboring cell's signal becomes stronger than a predefined threshold, the handoff process is triggered.
  3. Handoff Decision:
    • The mobile device, in consultation with the network infrastructure, makes a decision on whether to initiate a handoff.
    • Decision parameters may include signal strength, quality, load balancing considerations, and the type of handoff (e.g., hard handoff or soft handoff).
  4. Authentication and Authorization:
    • The mobile device communicates with the target cell and initiates the handoff request.
    • Authentication and authorization procedures are performed to ensure that the mobile device is allowed to connect to the target cell.
  5. Channel Assignment:
    • The network allocates a communication channel in the target cell for the mobile device.
    • This may involve selecting a new frequency or time slot for communication.
  6. Handoff Execution:
    • The mobile device, guided by the network, switches its connection from the current serving cell to the target cell.
    • Depending on the type of handoff, this transition can be seamless (soft handoff) or involve a brief interruption (hard handoff).
  7. Radio Link Establishment:
    • Once the handoff is complete, a new radio link is established between the mobile device and the target cell.
  8. Quality Check and Optimization:
    • The network continuously monitors the quality of the established link and optimizes parameters to ensure efficient communication.