A RANDOM-ACCESS MICRO-CELLULAR SYSTEM BASED ON CSMA AND POWER-CONTROL

A random access micro-cellular system based on CSMA (RAMCS/CSMA) is pr oposed. On uplink in RAMCS/CSMA, packets are transmitted by means of C SMA at the same carrier frequency in any cell. On downlink, packets ar e broadcast conforming to TDMA, also at the same carrier Frequency in any cell. In RAMCS/CSMA, deployed microcells produce higher system cap acity. Nevertheless, ''handoff on a terminal'' isn't required. In this paper, overview of the system, fundamental uplink performance, and tw o kinds of power control methods are presented. As for the control met hods, one is control according to packet priority. The other is a way according to location of a mobile terminal. By means of CSMA, throughp ut performance on uplink becomes great and is saturated at 0.39 per ce ll. And the performance strongly depends on the threshold level on car rier sense. Such a throughput performance is peculiar to RAMCS/CSMA an d different from an ordinary CSMA system. The optimum threshold is als o indicated here. Furthermore, it is clarified that both power control methods highly improve the throughput performance. As a result, it is found that RAMCS/CSMA is excellent for mobile communications.