Performance analysis of slotted nonpersistent CSMA with an adaptive array and canceling signal

Slotted nonpersistent CSMA with an adaptive array is known to obtain high throughput when a number of terminals transmit data packets to a base 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 complete. This causes throughput degradation. In this paper, we propose a slotted nonpersistent CSMA with an adaptive array and canceling signals to improve throughput performance. In the proposed model, the base station transmits a canceling signal to the terminals at the end of the transmission period of the acquired packet or at the time a failure occurs. The terminals cancel transmitting packets as soon as the terminals receive the canceling signal. We evaluate the throughput S and the 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 nonpersistent CSMA with an adaptive array.