In recent decades, with the increase in usage of wireless devices for a wide and varying range of applications, we experience a situations where the radio spectrum to be utilized in a better way. But in several cases parts of the spectrum remains unused by the licensed users there by resulting in the wastage of the radio spectrum. The unused parts of the radio spectrum bands result in spectral holes which if used effectively can be utilized among the unlicensed users whenever there is no intervention from the licensed users. The spectrum holes can be identified and can be made useful for the unlicensed secondary users. In this aspect we need to identify the available spectrum hole which is best suitable for the proper utilization of the secondary user. This task has to be done without any interference of the primary users and it also should consider the occupied spectrum holes. The main challenges faced in the routing protocol were as follows firstly, the routing module should be aware about the physical environment and such that an accurate decision can be made in path selection. Secondly the path needs to be maintained in case of any interference from the primary user. Thirdly in case of sudden appearance of the primary user may leads to the identification of an alternative path if necessary and it may cause a delay in the routing procedure and in some cases it may also leads to a link failure and requires rerouting. Considering these challenges we have proposed a system where it undertakes the routing process considering the overall delay and also the load maintenance at each node as the metrics. An Energy efficient routing protocol for a multi hop cognitive radio network is proposed in the research article based on the energy detective sensing and also the routing decision is being based on the Channel Quality Indicator. And the obtained results were presented in an analytical framework and a better and its approach is followed and discussed.
Dileep Reddy, B., & Shivashankar. (2019). Energy efficient protocol for multi hop routing in cognitive radio networks. International Journal of Recent Technology and Engineering, 7(6), 1476–1481.