Direct-Detection Optical Synchronous CDMA Systems with Interference Canceller Using Group Information Codes


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E83-A    No.11    pp.2138-2142
Publication Date: 2000/11/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section LETTER (Special Section on Spread Spectrum Techniques and Applications)
CDMA,  multiple access interference,  interference canceller,  group information codes,  

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We propose a new interference cancellation technique using reference signals for optical synchronous code-division multiple-access (CDMA) systems. In the proposed system, we use the signature code sequences composed of the group information codes and the modified prime code sequences. The group information codes are added in the forefront of the signature code sequences to estimate the amount of the multiple access interference (MAI). The proposed cancellation scheme can be realized with the simpler structure than the conventional canceller using the time division reference signal, because it can reduce the number of optical correlators from P to two where P is the prime number. We analyze the performance of the proposed system with considering the effects of the MAI, avalanche photodiode (APD) noise, and thermal noise. We show that the proposed canceller has better bit error probability than the conventional canceller.