Performance of coherent multi-carrier/DS-CDMA and MC-CDMA for broadband packet wireless access

This paper compares the packet error rate (PER) performance of three access schemes, i.e., single-carrier (SC)/DS-CDMA, multi-carrier (MC)/DS-CDMA, an d MC-CDMA assuming an 80-MHz bandwidth in order to achieve an optimum broad band packet wireless access scheme. In a broadband propagation channel, sev ere multipath interference degrades the accuracy of timing detection of mul tipath components (path search) and channel estimation required for coheren t detection. Computer simulation results show that, in the reverse link, SC /DS-CDMA achieves better performance than MC/DS-CDMA because the pilot sign al power in one sub-carrier required for path search and channel estimation decreases as the number of sub-carriers increases. The superiority of MC-C DMA to MC (SC)/DS-CDMA in the forward link is also demonstrated, because fr equency diversity is effectively utilized in association with the mitigatio n of a much longer symbol duration than the delay spread in MC-CDMA, meanwh ile a higher degree of multipath interference offsets the Rake time diversi ty in MC (SC)/DS-CDMA in a broadband multipath fading channel.