Achieving channel capacity using asymmetric signaling control in optical code division multiple access

Analysis of communication systems usually assumes a symmetric noninput-dependent channel; thus, Shannon capacity can be achieved using a balanced signaling. The optical-code-division-multiple-access channel is dominated by a multiple access interference, which is both asymmetric and input dependent. Consequently, using an unbalanced signaling which depends on the system characteristics can be used to optimize the mutual information of the channel. It is shown that for a given value of mutual information, the number of concurrent users can be significantly increased when the signaling distribution is biased and optimized by matching the source to the channel to achieve channel capacity.