Date Added: Apr 2011
In modern day wireless networks, spectrum utilization and allocation are static. Generally, static spectrum allocation is not a feasible solution considering the distributed and dynamic nature of wireless devices, thus some alternatives must be ensured in order to allocate spectrum dynamically and to mitigate the current spectrum scarcity. An effective technology to ensure dynamic spectrum usage is cognitive radio, which seeks the unutilized spectrum holes opportunistically and shares them with the neighboring devices. Using cognitive radio capabilities, the nodes are not restrained to static spectrum utilization, rather they can choose it on demand. However, dynamic spectrum usage raises several challenges, which need to be addressed in detail.