We address the problem of increasing the sum rate in a multiple-access systemfrom [1] for small number of users. We suggest an improved signal-codeconstruction in which in case of a small number of users we give more resourcesto them. For the resulting multiple-access system a lower bound on the relativesum rate is derived. It is shown to be very close to the maximal value ofrelative sum rate in [1] even for small number of users. The bound is obtainedfor the case of decoding by exhaustive search. We also suggestreduced-complexity decoding and compare the maximal number of users in thiscase and in case of decoding by exhaustive search.
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