A comparative study of multiple accessing schemes

We compare the performance of different accessing schemes (frequency division, time division and code division) for the uplink in a wireless communication system. We assume an additive white Gaussian noise channel with multipath fading. We consider the case when the receiver can track the channel parameters, but the transmitters cannot. We look at three different measures of performance: the Shannon capacity, the delay limited capacity and probability of outage. Shannon capacity is better suited for systems where the delay requirements are not as stringent, whereas the delay limited capacity and probability of outage give the performance when there are strict delay requirements or when the channel is slowly fading. We observe that all three schemes have the same achievable rates of transmission in Shannon sense, but the code division multiple access scheme performs better than frequency and time division in terms of delay limited capacity and probability of outage.