Throughput analysis of CDMA systems using multiuser receivers

Throughput bounds are attained for random channel access multichannel code- division multiple-access (CDMA) systems and spread slotted Aloha systems em ploying multiuser receivers. It is shown that the normalized throughput of these two systems reaches 1.0 exponentially fast in the region r/K < 1, whe re r is the average number of simultaneous users in each channel in the ran dom channel access multichannel CDMA system and the packet arrival rate in the spread slotted Aloha system, respectively, and K is the maximum number of users which the multiuser receiver can handle at the same time. Therefor e, both of the random channel access multichannel CDMA system and the sprea d slotted Aloha system employing multiuser receivers can achieve perfect th roughput while being stable in the region r/K = 1 - delta, delta > 0, The m aximum throughput of the random channel access multichannel CDMA systems is found as K - root (1 - (1/M))K log K - O(log K), where M is the number of channels in the system. The maximum throughput is reached when the average number of simultaneous users maximum throughput of the spread slotted Aloha systems is K - rootK log K - O(log K). The maximum throughput is reached w hen the packet arrival of Poisson distribution has the arrival rate lambda (m) = K - rootK log K + O(rootK/log K).