Performance Comparison of Various Multicode Modulation Schemes for High-Rate Wireless Data Transmission
Multicode modulation is a modulation technique which can allow transmission of high-speed data over wireless links. The basic idea behind this method is that high-rate information bits are converted to parallel low-rate bit streams in order to make the transmitted signal less sensitive to time delay spread. Each low-rate bits is then modulated by a code, which is a combination of orthogonal codes and spreading sequences, on a single carrier. In this paper, we investigate the use of various combination of orthogonal codes and signature sequences in multicode modulation and propose a low-complexity receiver structure which uses Fast Walsh Transform or Fast Fourier Transform. To further improve system performance, we consider the use of antenna diversity, interleaving, and convolutional coding. Sample numerical results which illustrate the potential of multicode modulation over multipath Rayleigh fading links will also be presented.