TRM-MAC: A TDMA-based reliable multicast MAC protocol for WSNs with flexibility to trade-off between latency and reliability

Multicast in wireless sensor networks (WSNs) is an efficient way to deliver the same data to multiple sensor nodes. Reliable multicast in WSNs is desirable for critical tasks like code updation and query based data collection. The erroneous nature of the wireless medium coupled with limited resources of sensor nodes, makes the design of reliable multicast protocol a challenging task. In this paper, we propose a framework for reliable multicast transmission in WSNs using TDMA-based channel access which works on top of a Multicast Spanning Tree (MST) rooted at the base station. The existing TDMA-based MAC protocols do not provide any mechanism to handle the collision and explosion of feedback messages, and therefore, they cannot be used in the proposed framework to support reliable multicast. To handle this issue, we propose a TDMA-based reliable multicast MAC (TRM-MAC) protocol for WSNs. The TRM-MAC protocol is parametric in the sense that it can be used to trade-off between reliability and delay performance, as per the requirement of the underlying applications. We have analyzed the TRM-MAC protocol to evaluate its delay and reliability performance at different packet loss rates, and have also compared its performance with those of others using simulation study. Both simulation and analytical results show that the TRM-MAC protocol considerably improves the performance of multicast communication in WSNs.