MLMAC: Multi-channel Low-latency MAC Protocol for Industrial Wireless Sensor Networks

Duty cycle MAC protocols achieve high energy efficiency and they are widely used in wireless sensor networks. However, they often suffer long end-to-end latency due to multi-hop sleep delay and are not suitable for industrial applications. RMAC, which employs multi-hop reservation mechanism, shows great advantage in reducing end-to-end latency than other duty cycle MAC protocols. However, due to interference between nodes, the performance of RMAC degrades when multiple flows is close to each other. In this paper, we propose MLMAC, which exploits multiple channels to solve the inter-flow interference problem. We also propose an enhanced reservation mechanism to allow a node to handle multiple reservations in a single transmission cycle. We evaluated the performance of MLMAC in NS-2. The simulation results show that MLMAC achieves significant performance improvement in end-to-end latency and energy efficiency.