WICKPro: A Hard Real-Time protocol for Wireless Mesh Networks with chain topologies

Wireless Mesh Networks (WMNs) with chain topologies are very useful in road and railroad transportation or in tunnel and mine applications. The proposed protocols for WMNs usually support best-effort traffic or some kind of Quality of Service (QoS). However, some applications such as remote-controlled machines in industrial control networks have Hard Real-Time (HRT) requirements, i.e., strict deadlines. Moreover, voice, video and data communications can be added to HRT traffic in order to provide them with reserved bandwidth and bounded latency. For this reason, this paper presents WICKPro (WIreless Chain networK Protocol), a HRT protocol for WMNs with chain topologies. WICKPro is a token-passing approach and is based on the ideas of the Timed-token protocol and the cyclic executive. We have designed this protocol to work on top of IEEE 802.11, made a testbed using commercial 802.11 wireless cards and compared the protocol´s performance with the 802.11 protocol and three specific protocols for WMNs with chain topologies.