icbnet

Research on the design and implementation of next generation wireless networks continues to grow, as the demand for high data rates and multimedia communications increases. In 2009, the Orthogonal Frequency Division Multiple Access (OFDMA) physical layer protocol was adopted for the Long Term Evolution (LTE) of third generation (3G) wireless networks. Next generation networks (4G – Fourth generation) will be in position to provide increased peak data rates compared to 3G mobile networks as well as increased spectrum efficiency and reduced radio network delay. Αnother promising technique that increases total throughput without additional spectrum requirements is the use of multiple antennas at both ends (transmission and reception) of a wireless link, also known as MIMO (multiple input – multiple output). MIMO systems can provide array gain, diversity gain as well as spatial multiplexing gain. However, these benefits cannot be obtained at the same time due to contradictory demands: In diversity transmission mode the same information is transmitted across all links of the MIMO configuration properly weighted; hence bit error rate (BER) is reduced. In spatial multiplexing mode independent data streams are transmitted from different antennas, hence transmission rate is increased with the cost however of reduced BERs, as diversity order is reduced. The integration of MIMO transmission techniques in wireless OFDMA networks is a challenging task as it combines two promising technologies for data rate maximization. Nevertheless, the proper design of a next generation wireless network is a multidimensional problem that combines several issues related to physical layer procedures apart from physical layer protocol implementations: feedback techniques and associated burden in order to schedule transmission according to channel conditions, design and placement of base stations, as well as optimum allocation of network resources for capacity maximization. The aim of the proposed study is to evaluate and develop methods such as transmission and feedback techniques, deployment of multiple antennas at both transmission ends, optimal design of network topologies, adaptive radio resource allocation, cross-layer design issues, reduction of hardware complexity at the transceivers and issues related with electromagnetic compatibility.