PERFORMANCE ANALYSIS OF SLOTTED NONPERSISTENT CSMA WITH AN ADAPTIVE ARRAY AND CANCELING SIGNAL

Slotted nonpersistent CSMA with an adaptive array is known to obtain h igh throughput when a number of terminals transmit data packets to a b ase station over a common radio channel. However, in this scheme, the terminals cannot begin to use a channel while the interfering packets are transmitted, even if the transmission of the acquired packet is co mplete. This causes throughput degradation. In this paper, we propose a slotted nonpersistent CSMA with an adaptive array and canceling sign als to improve throughput performance. In the proposed model, the base station transmits a canceling signal to the terminals at the end of t he transmission period of the acquired packet or at the time a failure occurs. The terminals cancel transmitting packets as soon as the term inals receive the canceling signal. We evaluate the throughput S and t he average number of transmissions and schedulings G/S by theoretical analysis and computer simulation. It is shown that the proposed model attains higher S and smaller G/S than the conventional slotted nonpers istent CSMA with an adaptive array. (C) 1998 Scripta Technica.