Asymptotically Optimal Coding Strategy for L-out-of-K Gaussian Channel using CDMA and Successive Decoding

| We introduce a new multiaccess coding strategy called stripping CDMA for a LOOK AWGN channel. Stripping CDMA can be viewed as a generalization of the regular CDMA scheme to one that can achieve arbitrarily high bandwidth eeciency. It can also be viewed as a modiication of the pure stripping scheme to one that is suited for multiaccess channel with bursty users. In this scheme, each user is split into M subusers and the decoder consist of M stripping stages using only single-user decoders. All transmitters of all users are identical, making it suitable for bursty user environment where the set of active users is not known in advanced. No synchronization between users at the phase, symbol, or frame level is needed. Although the scheme is only optimal asymptotically in M, it is close to optimal for small M, depending on the bandwidth eeciency. Performance of this scheme using existing non-optimal convolutional code is also investigated.