Channel Allocation Strategies in Computer Network

Channel Allocation means to allocate the available channels to the cells in a cellular system. When a user wants to make a call request then by using channel allocation strategies their requests are fulfilled. Channel Allocation Strategies are designed in such a way that there is efficient use of frequencies, time slots and bandwidth. 

Types of Channel Allocation Strategies:

These are Fixed, Dynamic, Hybrid Channel Allocation and Borrowing Channel Allocation as explained as following below.

Fixed Channel Allocation (FCA):  

Fixed Channel Allocation is a strategy in which fixed number of channels or voice channels are allocated to the cells. Once the channels are allocated to the specific cells then they cannot be changed. In FCA channels are allocated in a manner that maximize Frequency reuse.

In cell A 20 Channels or Voice channels are allocated. If all channels are occupied and user make a call then the call is blocked. Borrowing Channels handles this type of problem. This cell borrow channels from other cells.

• Advantages : 

1. Simple to implement and manage
2. Does not require complex equipment or algorithms

• Disadvantages :

1. Limited channel utilization as unused channels remain unused.
2. Susceptible to interference and congestion.

Dynamic Channel Allocation (DCA): 

Dynamic Channel allocation is a strategy in which channels are not permanently allocated to the cells. When a User makes a call request then Base Station (BS) send that request to the Mobile Station Center (MSC) for the allocation of channels or voice channels. This way the likelihood of blocking calls is reduced. As traffic increases more channels are assigned and vice-versa.

• Advantages :

1. Efficient use of available bandwidth.
2. Reduces call blocking and improves call quality.
3. Allows for dynamic allocation of resources.

• Disadvantages :

1. Requires more complex equipment and algorithms.
2. May result in call drops or poor quality if resources are not available

Hybrid Channel Allocation (HCA): 

Hybrid Channel Allocation is a combination of both Fixed Channel Allocation (FCA) and Dynamic Channel Allocation (DCA). The total number of channels or voice channels are divided into fixed and dynamic set. When a user make a call then first fixed set of channels are utilized but if all the fixed sets are busy then dynamic sets are used. The main purpose of HCA is to work efficiently under heavy traffic and to maintain a minimum S/I.

• Advantages :

1.   Provides the benefits of both FCA and DCA.
2.   Allows for dynamic allocation of resources while maintaining predictable call quality and reliability.

• Disadvantages :

1. Requires more complex equipment and algorithms than FCA.
2.  May not provide the same level of efficiency as pure DCA.

Borrowing Channel Allocation (BCA):

 when a cell experiences high traffic demand and all of its channels are occupied, it can borrow channels from neighboring cells that are not being used at that time. The borrowed channels are assigned to the busy cell and are used to support the additional traffic demand. Once the demand subsides, the borrowed channels are released and returned to their home cell. BCA can be implemented manually or automatically using algorithms or policies but the main disadvantage is that if the borrowed channel is reclaimed by the original cell the call drop may occur.

• Advantages :

1.  Efficient use of available bandwidth.
2.  Reduces call blocking and improves call quality.

• Disadvantages :

1. Increases interference between cells.
2. Can cause call drops if borrowed channels are reclaimed by the home cell.