Two innovative energy efficient IEEE 802.15.4 MAC sub-layer protocols with packet concatenation: employing RTS/CTS and multichannel scheduled channel polling

Abstract

This chapter proposes an IEEE 802.15.4 medium access control (MAC) sub-layer performance enhancement by employing request-to-send/clear-to-send (RTS/CTS) combined with packet concatenation. The results have shown that the use of the RTS/CTS mechanism improves channel efficiency by decreasing the deferral time before transmitting a data packet. In addition, the sensor block acknowledgement (ACK) (BACK) MAC (SBACK-MAC) protocol has been proposed that allows the aggregation of several ACK responses in one special BACK response packet. Two different solutions are briefly considered. The first one considers the SBACK-MAC protocol in the presence of BACK request (concatenation) while the second one considers the SBACK-MAC in the absence of BACK request (piggyback). The throughput and delay performance is mathematically derived under both ideal conditions (a channel environment with no transmission errors) and nonideal conditions (a channel environment with transmission errors). An analytical model is proposed, capable of taking into account the retransmission (RTX) delays and the maximum number of backoff stages. The simulation results successfully validate analytical model. Besides, an innovative efficient multichannel MAC (McMAC) protocol, based on SCP-MAC, has also been proposed, the so-called multichannel scheduled channel polling MAC (MC-SCP-MAC) protocol. The influential range (IR) concept, denial channel list (which considers the degradation metric of each slot channel), extra resolution (ER) phase algorithm and frame capture effect are explored to achieve the maximum performance in terms of delivery ratio and energy consumption. It is shown that MC-SCP-MAC outperforms SCP-MAC and multichannel lightweight medium access control (MC-LMAC) in denser scenarios, with improved throughput fairness. Considering theIR concept reduces the redundancy level in the network facilitating to reduce the energy consumption whilst decreasing the latency. The conclusions from this research reveal the importance of an appropriate design for the MAC protocol for the desired wireless body sensor network (WBSN) application.