Effective throughput for coded OFDM/SDMA systems with pilot-assisted channel estimation

This paper investigates the performance of coded orthogonal frequency division multiplexing (OFDM) systems with receiving adaptive array through which multiple users with single-element transmitting antenna are supported simultaneously in spatial division multiple access (SDMA). We characterized the performance of an OFDM/SDMA systems by effective throughput, which is essentially the average number of data bits in an OFDM symbol after considering the erroneous packet transmissions and modulation scheme by excluding the overhead from coding and pilots for channel estimation. Optimization of system operating parameters can be achieved through the maximization of effective throughput. The focus of the performance of coded OFDM/SDMA systems. Through extensive computer simulation, we show that using more pilots always improves bit error rate (BER) performance, but may reduce effective throughput. The optimal number of pilots together with the modulation scheme can be determined by maximizing the effective throughput for given operating signal-to-noise ratio (SNR). It is also shown that the system performance degrades gradually with the increase of users. For a system with a six-element adaptive array, the effective throughput with 5 users is lower than that with 4 users for a certain range of SNR. This indicates that the maximal number of users supportable by the system should consider the effective throughput.