RIMAP: Receiver-initiated MAC protocol with Adaptive Polling Discipline

This work introduces the Receiver-Initiated MAC with Adaptive Polling Discipline (RIMAP), a unicast MAC protocol that dynamically selects a polling discipline according to channel contention and link quality homogeneity to all neighbors. For that, two polling disciplines are considered: one that prioritizes nodes according to the likelihood of successful handshake (LSH), and another that targets throughput fairness among nodes, the proportional fair (PF) discipline. The adaptive behavior is controlled by two switching parameters that can be tuned to trade fairness with throughput-delay performance. To control its polling rate, RIMAP uses a reversed version of the binary exponential backoff (BEB) algorithm of the IEEE 802.11 DCF. Additionally, it implements a frame reordering technique that relax the need for data frames to reach the head of the queue in order to be transmitted, and a Nothing-To-Send (NTS) control frame to speed up polling rounds. RIMAP performance is evaluated with discrete-event simulations under topologies with hidden terminals, concurrent transmissions, and saturated traffic. Also, its performance is compared with the same BEB-based MAC protocol under fixed polling disciplines (LSH or PF only), as well as with the IEEE 802.11 DCF MAC, a representative of sender-initiated paradigms.