Spectrum selection scheme for dynamic spectrum access in cognitive radio networks.

M. Tech. Electrical EngineeringThe radio frequency (RF) spectrum is a natural resource used by wireless network operators to provide radio communication and transmission systems. The availability of RF spectrum to various wireless network operators using large bandwidth and more than one channel, as demanded by their offered services, is challenging, due to RF spectrum scarcity and lack of optimal channel selection. On the other hand, the under-utilisation of licensed spectrum by some primary users' (PU's) networks may be improved by the use of dynamic spectrum access (DSA) techniques. Recent research has shown that a large portion of the assigned spectrum is used irregularly, leading to under-utilisation and waste of valuable frequency resources. The notion of cognitive radio (CR) was introduced to increase the effectiveness and efficiency of spectrum consumption. In a cognitive radio network (CRN), each secondary user (SU) is expected to select the best RF spectrum band for opportunistic use when the PUs have temporarily vacated the spectrum allocated to them. The literature has proposed many spectrum selection methods for selecting vacant spectra in CRNs. However, most of these methods do not consider the channel usage pattern over time by PUs and also do not adequately consider the effect that frequent channel-switching might have on the quality of service requirements of the SUs and the throughput of the CR system. Thus, the proposed scheme, which is heuristic-based spectrum selection scheme for minimal channel switching (HBSSS-MCS) and heuristic-based spectrum selection scheme for maximum throughput (HBSSS-MT) addresses these issues. The main study objectives were as follows: 1) Minimise the frequent switching of channels using HBSS-MCS; 2) Maximise the throughput of the CR system using HBSSS-MT. To achieve the objectives of this research work, the following sub-problems were addressed: 1) To investigate the spectrum selection schemes in cognitive radio network (CRN); 2) To design a learning mechanism to facilitate the selection of a suitable channel in the primary network