Design and Implementation of Guard Band Aware Channel Assignment Method in Cognitive Radio System

Effective utilization of licensed portions of the radio spectrum is possible with the use of intelligent wireless radio communication system known as Cognitive radio (CR) system. This is done by carrying out spectrum sensing, post which the best-suited unused spectrum is accommodated with the requesting secondary users, this act being termed channel assignment. Multiple algorithms have been developed in the past, to carry out channel assignment, the vastly existing mechanism being- Sequential Assignment. In this method, spectrum sensing is executed, post which secondary users are assigned to the idle bands present, in a sequential manner. There is no provision to accommodate multiple users as well as to consider variable data rates, which limits the efficiency of the system. Another concern is the effect of Adjacent Channel Interference (ACI). ACI refers to the phenomenon of faulty filters degrading the efficiency of adjacent filters. There are no proposed systems to eradicate this. Hence, to maximize the efficiency of the Cognitive Radio system, along with a provision to eliminate ACI, we propose the Multiple User Variable Rate Guard Band-Aware Assignment (MUVR-GB Aware) Method. The MUVR is a smart method to improve spectrum efficiency with instantaneously allocating channels to several CR transmissions at different time slots by considering channel-dependent achieved transmission rates. This scheme enables the accommodation of multiple users in a single spectrum, based on the data rates required, which results in high system efficiency. The addition of Guard Bands is to make sure ACI has no adverse effects on the spectrum. It has been observed post simulations, that the MUVR-GB Aware assignment exhibits minimum wastage of the spectrum along with maximum secondary user accommodation, as compared to the existing Sequential Assignment.