Low latency multichannel LMAC protocol for wireless sensor networks

Abstract

Wireless sensor networks consist of a large number of resource constraint sensor nodes. Due to it’s wide range of applications, it has drawn much attention in the research community. As wireless sensor networks use shared medium, designing an energy efficient MAC protocol is highly desirable for maintaining other application specific performance requirements. Between contention-based and schedule-based MAC protocols; contention-based MAC protocol consumes much energy and cost higher for collision, idle listening and overhearing problem. In the contrary, schedule-based MAC protocol ensures energy efficient operation at the cost of high end-to-end delay. Although existing lightweight medium access control (LMAC) protocol is an energy efficient protocol, it introduces high end-to-end delay and low network throughput due to the long waiting time. The low throughput problem of LMAC protocol has already been mitigated in multichannel LMAC (MC-LMAC) protocol by ensuring energy efficient operation. However, the delay problem still exists for the same reason of the long waiting time. Therefore, it is highly expected to design an energy efficient MAC protocol for delay sensitive and high throughput applications. In this research work, a low latency multichannel LMAC (LL-MCLMAC) protocol is presented for WSNs which significantly reduces the end-to-end delay while improving the system throughput further. In the proposed protocol, the delay problem of existing LMAC and MC-LMAC protocol has been significantly improved by allowing a node to send its packet using two timeslots of a channel from multiple channel. The timeslot pair are kept half of the frame time separated which is decided by an algorithm. Moreover, the schedule-based operations ensure an energy efficient operation and use of multichannel results high throughput. A simulation model using OMNeT++ and MiXiM is designed to show the effectiveness of the proposed protocol. Finally, performance of proposed protocol is compared with the existing LMAC and MC-LMAC protocol, in terms of number of received packets, end-to-end delay, energy consumption and network lifetime. Simulation results clearly show that LL-MCLMAC achieves significant improvement in end-to-end delay and network throughput over existing LMAC and MC-LMAC protocols while ensuring an energy efficient operation.