Random assignment/transmitter-oriented code scheme for centralized DS/SSMA packet radio networks

We address an issue of channel sharing among users by using a random assignment/transmitter-oriented (RA/T) code scheme which permits the contention mode only in the transmission of a header while avoiding collision during the data packet transmission. Once the header is successfully received, the data packet is ready for reception by switching to one of the programmable matched-filters. But the reception may be blocked due to a limited number of matched-filters so that this effect is taken into account in our analysis. We also consider an acknowledgment scheme to notify whether the header is correctly detected and the data packet can be processed continuously, which aims at reducing the interference caused by unwanted data transmission. For a realistic analysis, we integrate the detection performance at the physical level with the channel activity at the link level through a Markov chain model. It is shown that compared to classical code-division multiple-access (CDMA) systems, a reduction in the receiver complexity of a half is allowed by choosing a proper number of RA/T codes without losing the performance quality in view of the normalized throughput.