On the Performance of Industrial Wireless Sensor Networks: Channel Hopping vs. Channel Adaptive Protocols

Abstract

The standard IEEE 802.15.4e shows several improvements which makes it outperforming the predecessor IEEE 802.15.4 standard. A remarkable improvement is the use of multiple channels and the capability to choose the most convenient depending on the network links state. Hence, different techniques can be provisioned to dynamically select the most appropriate channel for establishing the link through an adaptive mechanism. During the contention-free periods, the Time-Slotted Channel Hopping (TSCH) mode is based on channel hopping while the Deterministic and Synchronous Multi-channel Extension (DSME) mode uses either channel hopping or channel adaptation. In scenarios where channel diversity techniques are used for channel adaptation nodes links are established using the same channel as long as the channel quality (SNR) is high enough. In consequence to guarantee link best performance, its quality must be measured periodically to decide whether continue in the same channel of switch to a better performance one. Our investigation focuses on the analysis of the performance of three different approaches which pretend to take advantage of the multichannel capabilities of the new standard, based on the DSME protocol: CH-DSME which is based on a simple channel hopping mechanism, CA-DSME which employs channel adaptation, and a novel hybrid approach (H-DSME) which combines channel hopping and channel adaptation. This investigation shows that, in an industrial environment, the H-DSME outperforms both CH-DSME and CA-DSME approaches. In this work, the Castalia simulator was used to perform the simulations, using a reliable simulation model, which captures the characteristics of the wireless channel in industrial environments in long range basis. The analysis demonstrates that channel adaptation is better than channel hopping for unicast packets transmission, when links quality are continuously measured. Nevertheless, the coordinator transmit packets in broadcast mode, it is demonstrated that using channel hopping is a good alternative to deal with the quality spatial variation of the network channels.