ASAA: Multihop and Multiuser Channel Hopping Protocols for Cognitive-Radio-Enabled Internet of Things

The devices of the Internet of Things (IoT) are integrated and interconnected by using the traditional wireless communication technology. The unavailability of spectrum sharing occurs in traditional wireless communication due to the presence of a massive number of IoT devices. Thus, the cognitive radio network (CRN) is introduced as a promising technology to utilize the spectrum efficiently. Channel hopping sequence (CHS) is used to establish communication among CRN users. However, the majority of CHS mechanisms only focus on multiuser single-hop scenarios, which can lead to bottleneck and throughput degradation problems. It is also found that few existing CHS mechanisms still have a low percentage of rendezvous that can cause difficulties for the secondary users (SUs) to communicate. Thus, it is a challenge to design efficient CHS for establishing fast communication among SUs under multiuser, multihop scenarios, and asymmetric asynchronous environments. In this article, asymmetric synchronous and asymmetric asynchronous (ASAA) channel hopping (CH) algorithms are designed for the multiuser CRN-enabled IoT devices to share the unused spectrum in the multihop scenario. The multiuser asymmetric synchronous (MUAS) and multiuser asymmetric asynchronous (MUAA) protocols are designed in the proposed ASAA CH mechanism. The simulation results show that the proposed ASAA CHS algorithms outperform the existing CHS mechanisms in terms of throughput, channel loading (CL), channel utilization (CU), maximum time to rendezvous (MTTR), average time to rendezvous (ATTR), and maximum inter rendezvous interval (MIRI).