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Channel Assignment strategies means to allocate the available channels to the cells in a cellular system Whenever a user wants to make a call request then by using channel assignment strategies their requests are fulfilled. Channel Assignment Strategies are designed in such a way that there is efficient use of frequencies, time slots and bandwidth.
There are three types of Channel Assignment Strategies they are: Fixed, Dynamic, and Hybrid Channel Assignment.
Fixed Channel Assignment (FCA): It 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. Fixed channel assignment are very simple and requires least amount of processing. Cells in this strategy are allowed to borrow channels from adjacent cells if their channels are fully occupied while adjacent cells have free channels. No interference occurs by moving the channel from one cell to another.
Dynamic Channel Assignment (DCA): Dynamic Channel Assignment is a strategy in which channels are not permanently allocated to the cells. When a User makes a call request then Base Station send that request to the MSC (Mobile Station Cente) for the allocation of channels or voice channels. Each time a call request is made, serving BS requests a channel from the MSC. MSC assigns a channel only if it is not used and if it will not cause co‐channel interference with any cell in range. In this MSC has to collect real time data on channel occupancy, traffic distribution, radio signal strength indication of all channels on continuous basis, thus increasing the computational load on MSC.
Hybrid Channel Assignment (HCA): Hybrid Channel Allocation is a combination of both Fixed Channel Allocation (FCA) and Dynamic Channel Allocation (DCA). In this total number of channels or voice channels are divided into fixed and dynamic sets. If 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