Increasing the coverage and capacity of wireless networks using cognitive radio technology

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New standards such as LTE (Long Term Evolution) promise manifold increase in network capacity. However, the increase in demand for new multimedia applications is more than likely to devour this increased capacity more quickly than anticipated. Therefore, better use of the frequency spectrum will be essential for the future generations of wireless communication networks. According to several studies, a large part of the spectrum allocated to conventional services is underutilized. In early 2000's the idea of Cognitive Radio was introduced for addressing this issue. A cognitive radio (CR) senses the spectrum (finds spectral holes), analyzes the spectrum (finds the properties of the hole) and makes transmission decision (data rate, transmission mode, etc.). In a cognitive radio environment there are two types of users: Primary Users (PU) who are the legacy users of the spectrum and have the priority over others and the Secondary Users (SU). The latter are the ones using CR principles to use the otherwise wasted bandwidth. In Cognitive Radio usually the PU's have absolute priority over SU's. That is, when a primary user starts using the spectrum, the secondary user has to immediately vacate the frequency slot (s) it is using. In this research project our goal is to increase the spectrum efficiency by allowing coexistence of the PU's and SU's through the use of advanced channel coding techniques and multiuser detection. In cellular networks, the coverage deteriorates as the mobile approaches the border between the base stations and when leaving the last base station. Temporary circumstances can also contribute to the lack of radio capacity in certain areas. Cellular systems can use principles of CR to improve their coverage. LTE uses OFDMA as the access method. Orthogonal Frequency Division Multiplexing (OFDM) is a modulation techniques that can benefit from CR due to its flexibility and computational efficiency. In this project, we will consider the use of cognitive radio in an LTE environment with LTE as the primary user and WiFi as the Secondary user.