Tactical Wireless Communications and Networks: Design Concepts and Challenges

3.2 Channel Coding, Error Detection, and Error Correction

In Chapter 2, we discussed communications over a channel, where a symbol (could be one or multiple bits) is transmitted and received over the channel, independent of the previous or consecutive symbols. We covered many modulation techniques, and showed the probability of detecting a symbol in error while in the presence of AWGN. We also illustrated different channel molding techniques and their relationship to symbol error detection. If there is no inter-symbol interference, the demodulator can apply an optimum detection technique to decode each symbol by itself.

In this chapter, we have moved into information theory concepts. We have demonstrated that with channel coding, the input symbols to the modulator are interrelated, which introduced a memory aspect into the signaling over the channel. Although we introduced the concept of channel coding as mapping a block of bits to an encoded codeword, there are many different categories for channel coding. Depending on the channel coding technique,⁹ this interrelationship could either be addressed in a block-by-block manner or on a sliding window representation. Channel coding introduces redundancy in a controlled approach. The addition of channel coding can result in achieving reliable communications where the information symbol rate communicated over the channel can approach the physical limitation of the channel (channel capacity).

There are many ways to reach channel capacity, ...