A Dynamic Time Slot Allocation Scheme for Hybrid CSMA/TDMA MAC Protocol

The hybrid carrier-sense multiple access (CSMA)/time-division multiple access (TDMA) medium access control (MAC) protocol combines the strengths of CSMA and TDMA protocols. In this letter, we propose a dynamic queue-length-based time slot allocation scheme for the hybrid CSMA/TDMA MAC protocol to improve channel utilization considering the uncertainty in queue length information. Due to the lack of a dedicated control channel from a device to the coordinator, the queue length in a device can be reported to the coordinator only in an intermittent manner. To overcome this difficulty, the proposed scheme calculates the probability mass function (pmf) of the distribution of the queue length and allocates slots during the TDMA period based on this pmf. The simulation results show that the proposed slot allocation scheme outperforms the time slot allocation scheme which does not take into account the distribution of the queue length.