A general method for constructing codes for the T-user noiseless adder channel is proposed which achieves the largest sum rate known. The authors consider a multiple-access communication system. In this system, T statistically independent sources which use binary block codes C/sub 1/,...,C/sub T/ of equal length n, simultaneously transmit information via one common channel, maintaining synchronization with respect to words and bits. The output of the adder channel is the (T+l)-ary vector which is the component-wise arithmetic sum of the transmitted binary vectors. The task of the decoder is to uniquely determine the messages of all users.

A new approach to increase the sum rate for conventional synchronous code-division multiple-access (S-CDMA) systems is presented. It is shown that it can be done by joint processing of the outputs of matched filters, when one considers the system of codes for S-CDMA to be the codes for the usual adder channel. An example of construction and decoding of such a system is also given.>