No abstract

The increasing complexity of wireless standards has shown that protocols cannot be designed once for all possible deployments, especially when unpredictable and mutating interference situations are present due to the coexistence of heterogeneous technologies. As such, flexibility and (re)programmability of wireless devices is crucial in the emerging scenarios of technology proliferation and unpredictable interference conditions. In this paper, we focus on the possibility to improve coexistence performance of WiFi and ZigBee networks by exploiting novel programmable architectures of wireless devices able to support run-time modifications of medium access operations. Differently from software-defined radio (SDR) platforms, in which every function is programmed from scratch, our programmable architectures are based on a clear decoupling between elementary commands (hard-coded into the devices) and programmable protocol logic (injected into the devices) according to which the commands execution is scheduled. Our contribution is two-fold: first, we designed and implemented a cross-technology time division multiple access (TDMA) scheme devised to provide a global synchronization signal and allocate alternating channel intervals to WiFi and ZigBee programmable nodes; second, we used the OMF control framework to define an interference detection and adaptation strategy that in principle could work in independent and autonomous networks. Experimental results prove the benefits of the envisioned solution.

Abstract. Wireless sensor networks are used by an ever growing number of applications which have ever increasing Quality of Service requirements. The available unlicensed industrial scientific and medical bands -where wireless sensor networks typically operate -are crowded with a number of technologies interfering with each other. Delivering a sufficiently high QoS within these frequency bands is therefore becoming more and more difficult. A theoretic concept named Coexistence Aware Clear Channel Assessment (CACCA) promises more reliable QoS when different technologies utilize the same. Within this paper we propose two methods to perform CACCA and create an SDR prototype to show that CACCA can achieve a high packet error rate reduction in an IEEE 802.15.4 network when it coexists with IEEE 802.11.