Codeword Length Optimization for CPPUWB Systems

The optimal codeword length that generates the maximum output signal to interference ratio (SIR) for the channel-phase-precoded ultra-wideband (CPPUWB) system proposed in Y.H. Chang et al. (2006) is studied in this work to mitigate the interference in high data rate transmission. As compared with the proposed MMSE receiver in Y.H. Chang et al. (2006), this code length optimization technique demands no additional training symbols, which sacrifices the actual data rate, and maintains a simple receiver structure. This optimization problem is highly nonlinear in nature, and a fast search algorithm is developed to speed up the optimization process. The signal to interference plus noise ratio (SINR) performance of the proposed scheme degrades slightly when the input SNR is low, and it will converge to the maximum SINR as the input SNR becomes large