Co-channel interference cancellation technique using orthogonal convolutional codes

This paper proposes a new co-channel interference cancellation technique which utilizes orthogonal convolutional codes. For spread spectrum multiple access, co-channel interference (CCI) limits the performance of a communication link. To remove this interference, several CCI cancellation techniques have been proposed. Especially techniques which do not require the receiver to have knowledge of the cross-correlation between user sequences have been presented. However, these methods leave residual interference after the cancellation caused by errors on the initial decision. To reduce the residual interference and improve the initial decision, the proposed scheme utilizes the error correcting capability of the orthogonal convolutional code. This paper evaluates the performance of this scheme. It is shown that up to about 40 users, the proposed CCI canceler has a performance which is near the optimum performance when multiuser interference is completely canceled. It is also shown that the proposed CCI canceller offers an improvement in capacity by a factor of 1.5 approx. 3 as compared with a conventional canceller.