O-MAC: an optimized MAC protocol for concurrent data transmission in real-time wireless sensor networks

In this paper, we propose a new TDMA-based MAC protocol which aims at maximizing data transmission parallelism with two channels. The proposed protocol includes two key schemes, a channel allocation scheme and a slot allocation scheme. Each node determines a sending channel and a receiving channel by using the channel allocation scheme and a sending slot and a receiving slot by using the slot allocation scheme. The crux of these schemes lies in that they are performed in a distributed manner such that any two nodes two-hop away vertically are assigned different channels and same slot, and any two nodes four-hop away vertically are assigned the same channel and slot. The protocol structure consists of control transmission period for sending control messages to some specified nodes and data transmission period for periodic data acquisition from all nodes, thus allowing bidirectional communication for industry monitoring and control networks. According to the performance evaluation, the proposed protocol improved data throughput greatly and thus shortened data acquisition time significantly. In consequence, we expect that our protocol will satisfy the tighter time constraints for various real-time applications.