Industrial wireless sensor network (IWSN) applications are mostly timebound, mission-critical and highly delay sensitive applications therefore IWSN defines strict, stringent and unique QoS requirements such as timeliness, reliability and availability. In IWSN, unlike other sensor networks, late arrival of packets or delay or disruption to an on-going communication are considered as critical failure. Also, because IWSN is deployed in the overcrowded industrial, scientific, and medical (ISM) band it is difficult to meet this unique QoS requirements due to stiff competition for bandwidth from other technologies operating in ISM band resulting in scarcity of spectrum for reliable communication and/or disruption of ongoing communication. However, cognitive radio (CR) provides more spectral opportunities through opportunistic-use of unused licensed spectrum while ensuring minimal interference to licensed users. Similarly, spectrum handoff, which is a new type of handoff in cognitive radio, has the potential to offer increase bandwidth, reliable, smooth and interference-free communication for IWSNs through opportunistic-use of spectrum, minimal switching-delays, and efficient target channel selection strategies as well as effective link recovery maintenance. As a result, a new paradigm known as cognitive radio industrial wireless sensor network (CR-IWSN) has become the interest of recent research efforts. In this paper, we highlight and discuss important QoS requirements of IWSN as well as efforts of existing IWSN standards to address the challenges. We discuss the potential and how cognitive radio and spectrum handoff can be useful in the attempt to provide real-time reliable and smooth communication for IWSNs.Keywords: cognitive radio, industrial wireless sensor network, opportunistic use, spectrum handoff, quality of service. (Cheng et al., 2016;Silva et al., 2015;Silva and Hancke, 2016). Therefore, reliable and stable communication is of critical importance and top priority in IWSNs (Kumar S et al., 2014;Phala et al., 2016). For instance, in industrial automation; precision and timeliness are important and in industrial monitoring; availability, reliability, delay-intolerance, and robustness of communication links are key (Abu-Mahfouz and Hancke, 2011;Silva and Hancke, 2016). Yet, these requirements can be relatively difficult to achieve when operating in the ISM band due to interference and overcrowding which result in continuous switching, high latency due to switching, reduced link capacity and disruption of on-going communications. However, spectrum handoff can offer increase bandwidth, reliable, smooth and interference-free communication for IWSNs through opportunistic-use of spectrum, minimal switching-delays, and efficient target channel selection strategies as well as effective link recovery maintenance. A well-planned and designed spectrum handoff technique will provide reliable communication by reducing number of spectrum handoffs and maintaining quality communication link for IWSN systems and application...
