Channel Assignment Strategies in Mobile Communication Explained
Table of Contents
What are Channel Assignment Strategies?
Channel assignment strategies in mobile communication are used to allocate available radio channels to mobile users in a way that maximizes spectrum utilization and minimizes interference.
This is important because the radio spectrum is a limited resource, and there is a growing demand for mobile communication services.
Types of Channel Assignment Strategies
There are three main types of channel assignment strategies:
- Fixed channel assignment (FCA)
- Dynamic channel assignment (DCA)
- Hybrid channel assignment (HCA)
Fixed channel assignment (FCA)
In fixed channel assignment, each cell is allocated a fixed or predetermined set of channels (voice channels).
If all channels in a cell are occupied, the call from a mobile user is blocked and the user won’t receive service.
This strategy is simple to implement, but it can lead to inefficient spectrum utilization and increased interference if the traffic load is not evenly distributed across the cells.
Advantages of FCA:
- Simple to implement and manage
- Reduces co-channel interference
Disadvantages of FCA:
- Can lead to inefficient spectrum utilization
- Can lead to increased call blocking if traffic load is not evenly distributed across the cells
Dynamic channel assignment (DCA)
In dynamic channel assignment, channels are assigned to cells on demand, based on the current traffic load. i.e., there is no allocation of predetermined set of channels (voice channels).
This strategy is more efficient than FCA, but it is also more complex to implement.
Advantages of DCA:
- Improves spectrum utilization
- Reduces likelihood of blocking since all available channels are accessible to all cells
- Reduces co-channel interference
Disadvantages of DCA:
- More complex to implement and manage than FCA
- Can lead to increased call blocking if traffic load is high
Hybrid channel assignment (HCA)
HCA is a combination of FCA and DCA. In HCA, each cell is allocated a fixed set of channels, but additional channels can be dynamically assigned to cells if needed.
This strategy offers a good balance between simplicity and efficiency.
Advantages of HCA:
- Improves spectrum utilization compared to FCA
- Simpler to implement and manage than DCA
Disadvantages of HCA:
- Can be more complex to implement than FCA
- Can lead to increased co-channel interference compared to DCA
Channel Borrowing
Channel borrowing is a technique that can be used with any channel assignment strategy.
In channel borrowing, a cell can borrow a channel from a neighboring cell if all of its own channels are occupied.
This process is carried out by the Mobile Switching Center (MSC) which supervises the borrowing procedures and ensures that the borrowing of a channel does not interrupt or interfere with any of the calls in progress in the donor cell.
This technique can help to reduce call blocking and improve spectrum utilization.
Advantages of channel borrowing:
- Reduces call blocking
- Improves spectrum utilization
Disadvantages of channel borrowing:
- Can increase co-channel interference
Comparison of Channel Assignment Strategies (FCA, DCA and HCA)
| Channel assignment strategy | Advantages | Disadvantages |
|---|---|---|
| Fixed channel assignment (FCA) | Simple to implement and manage | Can lead to inefficient spectrum utilization, increased call blocking if traffic load is not evenly distributed across the cells |
| Dynamic channel assignment (DCA) | Improves spectrum utilization, reduces co-channel interference | More complex to implement and manage, can lead to increased call blocking if traffic load is high |
| Hybrid channel assignment (HCA) | Improves spectrum utilization compared to FCA, simpler to implement and manage than DCA | Can be more complex to implement than FCA, can lead to increased co-channel interference compared to DCA |
