Iterative decision-directed path search and channel estimation for multi-carrier/DS-CDMA broadband packet wireless access

This paper proposes an iterative timing detection of multipath components for coherent Rake combing (path search) and channel estimation method in multi-carrier/DS-CDMA (MC/DS-CDMA) broadband packet wireless access, such as 20 Mbps packet transmission over a 100 MHz bandwidth, including single-carrier/DS-CDMA (SC/DS-CDMA). In the proposed method, while the initial path search and channel estimation are calculated using only time-multiplexed pilot symbols at the beginning of a packet, their results are refined by repeating the path search and channel estimation using both pilot and decision-directed data symbols. Computer simulation results demonstrate that the measured required average received E_b/N₀ for a achieving the average packet error rate (PER) = 10^-2 can be improved by approximately 1.2, 1.3, 2.0, and 2.1 dB for the number of sub-carriers N_c = 1(SC/DS-CDMA), 4, 8, and 16, respectively, in an equal level 24-path Rayleigh fading channel, when the number of pilot symbols is 64 and the number of iterations is 1.