Analyzing Split Channel Medium Access Control Schemes with ALOHA Reservation

In order to improve the throughput performance of Medium Access Control (MAC) schemes in wireless communication networks, some researchers proposed to split the single shared channel into two subchannels: a control subchannel and a data subchannel. The control subchannel is used for access reservation to the data subchannel over which the data packets are transmitted, and such reservation can be done through the use of the dialogues such as RTS/CTS (Ready-ToSend/Clear-To-Send) dialogue. In this paper, we evaluate the maximum achievable throughput of split-channel MAC schemes that are based on RTS/CTS dialogues with pure ALOHA contention resolution mechanism. We derive and calculate numerically the probability density function (pdf) of the contention resolution periods on the control subchannel. We then apply these results to calculate the throughput of the splitchannel MAC schemes, which we then compare with the performance of the corresponding single-channel MAC schemes. Our results show that, when radio propagation delays are negligible, the maximum achievable throughput of the split-channel MAC schemes is lower than that of the corresponding single-channel MAC schemes in the scenarios that we have studied. Consequently, our results suggest that splitting the single shared channel of the MAC scheme in a wireless network should be avoided. Simulation results are presented to support our analytical results.