A CP-CDMA System with Comb Spectrum Codes and Its Performance Evaluation in Nakagami Fading Channels

Cyclic prefix code division multiple access (CP-CDMA) is a promising technology for broadband wireless communications. It can efficiently resist the multiple access interference (MAI) by the use of CP and frequency domain equalization in DS-CDMA systems. However, the equalization complexity, which is increased with bandwidth, hindered its application. A comb spectrum (CS) code was proposed to solve this problem. This technology combines the frequency orthogonality of orthogonal frequency division multiplexing (OFDM) to CDMA code design for grouping the codes and allows a significant reduction for the calculations in channel equalization. The proposed code design method divides the codes of M chips in length into N groups, which are orthogonal to each other in frequency domain. Each of the groups contains K codes which are mutually orthogonal in time domain. A CP-CDMA system with CS code is described and its complexity and BER performance are evaluated in this paper to show the effectiveness of the CS codes.