Title :
Soft MCI cancellation for turbo-coded OFCDM systems
Author :
Zhou, Yiqing ; Wang, Jiangzhou
Author_Institution :
Dept. of Electr. & Electron. Eng., Hong Kong Univ.
Abstract :
In this paper, the performance of turbo-coded orthogonal frequency and code division multiplexing (OFCDM) systems is investigated with soft multi-code interference (MCI) cancellation. To regenerate the soft interference signal, the conventional turbo decoding algorithm must be modified to provide log likelihood ratio (LLR) values for all coded bits. Based on the LLR outputs of turbo decoder, two soft decision functions are proposed, called LLR-soft-decision and Gaussian-soft-decision functions. By means of computer simulations, the performance of soft MCI cancellation is studied extensively and compared to that of hard ones. It is shown that in a highly frequency selective channel, the proposed soft decision functions outperform the hard decision function with various channel conditions and system parameters. Furthermore, the Gaussian-soft-decision function provides better performance than the LLR-soft-decision function
Keywords :
Gaussian channels; channel coding; code division multiplexing; frequency division multiplexing; interference suppression; least mean squares methods; turbo codes; Gaussian-soft-decision functions; MMSE; frequency selective channel; log likelihood ratio; orthogonal frequency and code division multiplexing; soft MCI cancellation; soft multicode interference cancellation; turbo-coded OFCDM systems; Code division multiplexing; Computer simulation; Decoding; Downlink; Gaussian processes; Interference; Neural networks; OFDM; Quadrature phase shift keying; Turbo codes;
Conference_Titel :
Wireless Communications and Networking Conference, 2006. WCNC 2006. IEEE
Conference_Location :
Las Vegas, NV
Print_ISBN :
1-4244-0269-7
Electronic_ISBN :
1525-3511
DOI :
10.1109/WCNC.2006.1696520