Cognitive Radio (CR) is an up-coming approach to stretch out the use of spectrum band. Various sensing techniques are used to detect the vacant bands among the given spectrum. Generally detection performance is compromised with receiver uncertainty, multipath fading and shadowing issues and effective method to alleviate the effect of these issues in CSS. In this paper, we have shown the solutions to the shadow fading using the two strong techniques known as the optimal spectrum sensing and greedy spectrum sensing. The optimal spectrum sensing has been implemented as the critical improvement in the existing model of greedy spectrum sensing. The optimal spectrum sensing is the technique which uses the time sharing sequence influenced by the energy detection scheme on the available spectrum. The spectrum schemes have been studied in the increasing bandwidth available over the given spectrum while keeping the level of shadowing similar. The simulated results have clearly indicated that the rise in bandwidth directly increases the throughput of the cognitive radio channel and optimal method is better than the greedy method.
