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The wireless channel is very important for making connections in a wireless network. By default, the radio signal is shared between the nodes. Those signals reach the neighbour via a wireless channel. This will go beyond many neighbours and eventually reach the packets destination. This requires a wireless connection between the nodes. Each node can select a channel to communicate with the next node within the coverage range between those nodes. Sometimes if there is more than one node within that coverage range then no other node will be able to select the channel until another node is exchanging information with the other node.
This situation can cause channel shortages between wireless nodes. If each node has cognitive technology, it will run cognitive when there is a channel shortage and see if there is another channel next to it that does not interfere. The viewed channel, it may be for the use of another node, if the node does not use that channel then the channel is within the coverage range of the node looking for the channel, the node can select and use that channel cognitively. Such cognitive technology and cognitive radio (CR) in wireless communication is introduced first by Joseph Mitola III (Mitola & Maguire, 1999). Cognitive radio is built based on the software defined radio (SDR) (Arslan & Mitola, 2007). In wireless communication, CR intelligently detects the unused channels and transfer the communication over it without causing any interference to the primary users. The Federal communication commission (FCC) provides the guidelines to the users about the radio spectrum use. According to FCC, spectrum utilization range is 15% to 85% due to temporal and geographical variation. Hence, FCC proposed dynamic spectrum access (DSA) in which unused licensed spectrum is allowed to unlicensed users also called as secondary users or cognitive users to use it. Many wireless communication devices can take advantages of cognitive radio technology over the 5G networks. With this technology, utilization of unused spectrum band will be maximized for the 5G wireless communication networks (Hindia et al., 2020).
If one node selects the channel of another node, whichever node is selected the channel will be treated as - secondary user - SU and the selected channel's node is treated as - primary user -PU. In this scenario a node can get information about a lot of channel for some time, or a lot of SUs can compete for a PU channel as like Figure 1. In this, SUs are the non-licensed users and competing to access the licensed spectrum of PU when it is not in use. SUs from the coverage range of the PU channel can compete for the same channel at the same time. This channel will be utilized by the secondary users (SUs) in time slot mode. Some SUs may need more time slot to finish their communication and some SUs may waste their time slot due to not using it fully.