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In packet radio networks, the hidden terminal problem and the exposed terminal problem can severely reduce the utilization of a medium access control (MAC) protocols. To avoid these problems, request-to-send/clear-to-send (RTS/CTS)-based schemes were proposed. However, as shown in this paper, utilization of these schemes is still degraded, especially in the cases in which the propagation and the transmission delays are long. We propose a new MAC protocol, termed dual busy tone multiple access (DBTMA), and we evaluate its performance. In DBTMA, two busy tones are used to separate the use of the forward and the reverse communication directions. the simulations show that the network utilization of DBTMA is about twice as that of RTS/CTS-based schemes. We also discuss the effect of nodal mobility on the network utilization in packet radio networks, concluding that it is negligible under normal operational conditions.
Deng et al. (Wed,) studied this question.