The Internet of Things (IoT) concept increases the spectrum demands of mobile users in wireless communications because of the intensive and heterogeneous structure of IoT. Various devices are joining IoT networks every day, and spectrum scarcity may be a crucial issue for IoT environments in the near future. Cognitive radio (CR) is capable of sensing and detecting spectrum holes. With the aim of CR, more powerful IoT devices will be constructed in such crowded wireless environments. Also, dynamic and ad-hoc CR networks have not a fixed base station. Therefore, CR capable IoT (CR-based IoT) device approach with routing capabilities will be a solution for future IoT environments. In this study, spectrum aware Ad hoc on-demand distance vector routing protocol is proposed for CR-based IoT devices in IoT environments. For the performance analysis of the proposed method, various network scenarios with different idle probability have been performed and throughput and delay results for different offered loads have been analyzed.
K E Y W O R D Scognitive radio, internet of things, routing protocol, wireless networks
INTRODUCTIONInternet of Thing (IoT) networks have different application areas and also have similar specifications. The basic similarity is having IP addresses on a specific spectrum band. The IoT devices can access the internet with a dedicated spectrum. In spectrum bands, there are two types of licensed and unlicensed users. The licensed users have the authorization to access the spectrum by paying a fee and they are called primary users (PUs). They have the right and priority to access to licensed spectrum whenever they want. The unlicensed users do not have not the authorization to access the licensed spectrum but they have advanced equipment for scanning the spectrum for holes and they are called secondary users (SUs). As can be seen from the literature, 1-3 the IoT users can be capable of CR capabilities and hence they can sense the overall spectrum for wireless transmissions.The CR networks can be constructed as infrastructure or ad-hoc manner as classical networks. 4,5 The base stations play important roles and they are required for control and transmissions in the infrastructure networks. Ad-hoc networks do not have base stations or access points for a central control mechanism. Each device in an ad-hoc network has routing information for packet transmissions. IoT devices can communicate with their neighbors periodically or on-demand in ad-hoc CR networks. Various parameters are taken into account for calculating effective routes to the destination. The routing parameters are signal-to-noise ratio (SNR), received signal strength indicator (RSSI), bit error rate (BER), bandwidth, utilization and so on. In addition to the aforementioned parameters, specific parameters must be considered in ad-hoc CR networks as required.The most important duty in CR networks is to determine the presence of licensed users in the spectrum. 6 Besides, it should be taken into account the unlicensed and licensed spectrum usa...