OSLMAC: One-step look-ahead MAC protocol for concurrent transmission over wireless ad hoc networks

摘要

The IEEE 802.11 DCF mechanism is a basic ad hoc MAC protocol. This protocol, however, is prone to the hidden terminal problem. To solve this problem, the incorporation of the request-to-send/clear-to-send (RTS/CTS) mechanism has been suggested; however, this can in turn result in the exposed terminal problem. Concurrent transmission can reduce the exposed terminal problem. The use of concurrent-transmission-based medium access control (MAC) protocols has been considered as a means of improving throughput in wireless ad hoc networks. In this paper, we propose a one-step look-ahead MAC (OSLMAC) protocol that uses a back-off reservation mechanism to increase throughput and utilizes control messages, which are required for concurrent transmission of messages. Currently, where a concurrent transmission state is not possible, redundant overhead comprising exchanged control messages is incurred. However, our proposed mechanism utilizes these wasted control messages to reserve the next data transmission. Thus, this mechanism decreases the number of collisions and reduces back-off waiting times. Evaluation of the performance of our proposed scheme, by means of simulations and comparison of its throughput with those of an existing scheme and the basic IEEE 802.11 DCF MAC, indicate that the measured performance metrics are improved when our proposed scheme is used.