先决条件——计算机网络中的信道分配问题
固定频道分配 (FCA)：
固定信道分配是一种将固定数量的信道或语音信道分配给小区的策略。一旦将信道分配给特定小区，就不能更改它们。在 FCA 中，以最大化频率重用的方式分配信道。
如果所有信道都被占用并且用户拨打电话，则呼叫被阻塞。 Borrowing Channels 可以处理此类问题。在这个单元格中从其他单元格借用频道。
动态信道分配 (DCA)：
动态信道分配是一种不将信道永久分配给小区的策略。当用户发出呼叫请求时，基站 (BS) 将该请求发送到移动台中心 (MSC) 以分配信道或语音信道。这样就减少了阻塞调用的可能性。随着业务量的增加，更多的信道被分配，反之亦然。
固定信道分配(FCA)和动态信道分配(DCA)的区别：
| Fixed Channel Allocation(FCA) | Dynamic Channel Allocation(DCA) | |
|---|---|---|
| Fixed number of channels or voice channels are allocated to cells. | Fixed number of channels are not allocated to cells. | |
| If all the channels are occupied and user make a call then the call will be blocked in FCA. | If all the channels are occupied and user make a call then Base Station(BS) request more channel to the Mobile Station Center(MSC). | |
| Frequency reuse is maximum because cells channels are separated by minimum reuse distance. | Frequency reuse is not that maximum in DCA because of channel randomness allocation. | |
| In FCA no such complex algorithms are used. | In DCA complex algorithms are used to decide which available channel is most efficient. | |
| Fixed Channel Allocation Strategy is less costly than the DCA | Dynamic Channel Allocation Strategy is costly because lot of computation is required in real-time. | |
| In FCA allocated channels remains to the cell, once the call is completed | In DCA once the call is completed then the channel or the voice channel return to the MSC. | |
| Mobile Station Center(MSC) has less responsibilities. | Mobile Station Center(MSC) has more signalling load and responsibilities. |