Performance evaluation of carrier interferometry implementations of MC-CDMA over a wideband channel suffering phase noise

In this paper the performance of carrier interferometry (CI) and pseudo-orthogonal carrier interferometry (PO-CI) [B. Natarajan et al., November 2001] implementations of multi-carrier code division multiple access (MC-CDMA) are investigated. Comparisons are made with the performance of traditional MC-CDMA (incorporating Hadamard-Walsh spreading codes) [S. Hara and R. Prasad, December 1997], [N. Yee and J.P Linnartz, 1993] and coded orthogonal frequency division multiplexing (COFDM) [R. Van Nee and R. Prasad, 2000]. These systems are simulated over a 20 MHz bandwidth, wideband, wide-sense stationary, statistically uncorrelated Rayleigh fading channel suffering additive white Gaussian noise (AWGN) and phase noise. The two channel models employed are consistent with the model B ´indoor and office´ and model B ´outdoor to indoor and pedestrian´ test environment specifications proposed by ETSI for UMTS terrestrial radio access (UTRA). The BPSK CI system was found to outperform both of the equivalent COFDM and MC-CDMA systems, providing 1 dB and 1.5 dB performance gains respectively at a bit error rate (BER) of 10^-3. The BPSK PO-CI system, shown to offer twice the capacity of the equivalent MC-CDMA, COFDM and CI systems, was found to offer the same performance as MC-CDMA, For higher order modulation schemes, the CI system´s performance was found to equal that of the equivalent MC-CDMA system, whilst the performance of PO-CI was found to be very poor. In the presence of phase noise, the CI system was found to outperform the MC-CDMA and COFDM systems, suffering a far lower performance loss for a given level of phase noise and providing a softer fail as this level was increased. This soft fail characteristic was also observed in the PO-CI system.