When there is more than one user who desires to access a shared network channel, an algorithm is deployed for channel allocation among the competing users. Static channel allocation is a traditional method of channel allocation in which a fixed portion of the frequency channel is allotted to each user, who may be base stations, access points or terminal equipment. This scheme is also referred to as fixed channel allocation or fixed channel assignment.
Suppose that there are N competing users. Here, the total bandwidth is divided into N discrete channels using frequency division multiplexing (FDM). In most cases, the size of the channels is equal. Each of these channels is assigned to one user.
Static channel allocation scheme is particularly suitable for situations where there are a small number of fixed users having a steady flow of uniform network traffic. The allocation technique is simple and so the additional overhead of a complex algorithm need not be incurred. Besides, there is no interference between the users since each user is assigned a fixed channel which is not shared with others.
Most real-life network situations have a variable number of users, usually large in number with bursty traffic. If the value of N is very large, the bandwidth available for each user will be very less. This will reduce the throughput if the user needs to send a large volume of data once in a while.
It is very unlikely that all the users will be communicating all the time. However, since all of them are allocated fixed bandwidths, the bandwidth allocated to non-communicating users lies wasted.
If the number of users is more than N, then some of them will be denied service, even if there are unused frequencies.