# 7.6 Combined coding and modulation

## Introduction

The problem with all the coding schemes described thus far is that they all increase the amount of data to be transmitted, requiring either increased transmission bandwidth or reduced channel capacity if the bandwidth is fixed. There is, however, one obvious method to recover any capacity loss and that is to increase the number of symbol states in the modulation scheme. We know that this will incur a large Eb/N0 penalty, but is this more or less than the coding gain that we can achieve with the extra channel capacity obtained? |

####