Information and cut-off rates for multiple-pulse position modulation on multi-path channels

The effect is examined of multipath dispersion on the information and cut-off rates of multiple-pulse position modulation. Over multipath channels, intersymbol interference (ISI) can reduce the information rate significantly. When the input codewords are independent and identically distributed with a uniform distribution, lower and upper bounds are presented for the information rate on a moderate ISI channel in terms of the average mutual information of a memoryless Gaussian vector channel with scaled input codewords. The cut-off rate of each modulation scheme is also examined in the presence of ISI, and the power required to achieve the cut-off rate is calculated for various bit rates over the channel 3 dB bandwidth