Turbo Coded CDMA System with an Interference Cancellation Technique

Hyuck-Chan KWON  Ki-Jun KIM  Byeong-Hoon PARK  Keum-Chan WHANG  

IEICE TRANSACTIONS on Communications   Vol.E81-B   No.12   pp.2326-2333
Publication Date: 1998/12/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on the Latest Development of Telecommunication Research)
Category: Wireless Communication Systems
turbo codes,  interference cancellation,  CDMA,  

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In this paper, we suggest the interference cancellation (IC) technique suitable for turbo coded code division multiple access (CDMA) systems, that merges IC processes into turbo decoding processes to improve system performance and reduce system complexity. To ensure the reliability of the temporary decision bits for cancellation, we use cyclic redundancy code (CRC) check as a measure. Prior to design turbo coded CDMA system, we first derive the optimized polynomials of low-rate turbo codes appropriate to CDMA systems. According to the simulation results with setting the processing gain (PG) to 120, the turbo coded CDMA system with the proposed IC technique can accommodate 60 users over additive white Gaussian noise (AWGN) channel when signal to noise ratio (SNR) is about 2. 5 dB and required frame error ratio (FER) is 10-2. Compared this result with the performance of single user's system, it requires only additional 1 dB SNR.