Efficient cooperative wireless communication techniques in MIMO system

Abstract

Recently, there are a lot of researches for a new mobile generation which is referred to 5G (5th generation mobile networks or 5th generation wireless systems). The requirements for 5G comes from the facts that the growth of global mobile data traffic use is drastically increasing in excess of current demands. It is supposed that 100Gbps for nomadic and low mobility might be the demand for high data rate in new mobile generation. However, it is known that technical development based on 4G, where 3rd Generation Partnership Project (3GPP) and Institute of Electrical & Electronics Engineers (IEEE) approved LTE (Long-Term Evolution), WIMAX, and HSPA+ as 4G technologies, cannot accomplish the goal of new mobile generation because of its non-cooperation characteristic. In this point of view, the cooperative communication technique can be a good solution for the cellular system equipped with muli-input multi-output (MIMO) not only to alleviate the technical limitation of the system but also to solve the potential risk of MIMO. In this dissertation, for the purpose of system performance enhancement, efficient cooperative wireless communication techniques in MIMO system are considered. Specifically, for the purpose of reducing co-channel interference, we investigate efficient transmission techniques under cooperation among cells and a cooperation methodology when considering multi-cells.

Firstly, under cooperation strategy, we investigate a pre-whitening scheme using partial channel state information (CSI) for MIMO cognitive radio(CR) systems. In order to reduce the processing burden and feedback information, we further extend the conventional pre-whitening technique with only the direction information of interference channel (as a partial CSI). First, we decompose the precoding matrix of a conventional pre-whitening scheme, in which full CSI is required, into direction and magnitude components. Then, we propose a precoder by using only the former, which projects the ...