Cognitive channel access for Wireless Local area networks used in IOT

Abstract

Technologies like Internet of things (IoT) not only push radio nodes to sense and hear wireless medium, but also provide opportunity to learn and adapt to radio neighborhood. With IoT envisioned to become new normal in our daily lives, spectrum scarcity and increased interference issues becomes non-trivial. As Wireless Local area networks (WLANs) like HiperLan from ETSI and 802.11 radios from IEEE are vital frontrunners to realize IoT technology, channel access algorithms at MAC layer play a vital role to attain maximum achievable throughput by managing spectrum and interference. Contention based, binary exponential back off CSMA/CA is default channel access mechanism for most 802.11 radios for sake of its simplicity and applicability in both ad-hoc and infrastructure modes. Even though contention free and polling based point coordinated function (PCF) is illustrated in IEEE 802.11 standards, it to be implemented along with distributed coordinated function (DCF), for adding new nodes to same channel. Time division multiple access (TDMA) based medium access layer (MAC) proposed for HiperLan by ETSI also implements RANDOM ACCESS PHASE to add new radios to channel. DCF, PCF and TDMA allow radios to access channel serially, as simultaneous parallel transmission by multiple radios can lead to collision because of Interference. In this paper a novel interference and spectrum aware channel access mechanism for WLANs, is proposed based on perceived RSSI, RCPI and SNR metrics and generating signal-strength-snr graph to allow multiple parallel transmissions possible in same channel.