Parallel Interference Cancellation Scheme Based on Sorting Method for a Multi-Carrier DS/CDMA System

Jaewon PARK
Shiquan PIAO
Yongwan PARK

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B    No.6    pp.1781-1792
Publication Date: 2006/06/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.6.1781
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
interference cancellation,  multi-carrier DS/CDMA,  multiple access interference,  

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Summary: 
In this paper, we introduce a Parallel Interference Canceller (PIC) based on a sorting method to improve the performance in the MC-DS/CDMA environment. A conventional PIC estimates and cancels out all of the MAI (Multiple Access Interference) for each user in parallel. The parallel process ensures a limited delay for the detection of all users. Since the performance of PIC is strongly related to the correct MAI estimation, we introduce an interference cancellation scheme to estimate accurately the MAI of the weaker interferers than the desired signal. The principle of proposed IC (Interference cancellation) scheme is to sort in descending order from the strength of the signal and subtracted by the MAI of the strong interferer from the weak signal. Therefore, the signal of the weak interferer becomes a better estimation. Following this, the output of the front processing is achieved by a rank operation of the signals in an ascending order of strength. Then the strong signal eliminates the improved weak interferer. Resulting from this, the proposed scheme obtains a better BER performance than the conventional PIC, because the accuracy of the strong signal has been improved. However, a disadvantage exists in that the processing time has a slightly longer delay than the PIC-1stage owing to a two step processing, including the sorting one.