Design Of Interference Steering For Cellular Networks

With the development of wireless communication technologies,the demands on data rate,network coverage and reliability are permanently growing,and interference has become a key impediment in network performance,thus making effective interference management(IM)essential to further development of network performance.There have been numerous interference management proposals at the interfering transmitter or the victim transmitter/receiver separately or cooperatively.Moreover,the existing IM schemes rely mainly on the use of channel state information.However,in some communication scenarios,the option to adjust the interferer is not available,and,in the case of downlink transmission,it is always difficult or even impossible for the victim receiver to acquire necessary information for IM.So the existing interference management proposals have great limitation on application scenarios.Based on the above observations,we design new IM schemes in cellular networks.First,we propose a novel IM technique,called orthogonal interference steering(OIS).By making use of both channel state information(CSI)w.r.t.and data carried in the interfering signal,OIS generates a signal to modify the spatial feature of the original interference,so that the steered interference at the victim receiver is orthogonal to its intended signal,then the interference can be eliminated.None of the existing interference management proposals are free of some form of cost,so it is important to balance the benefit brought by and cost of each adopted IM scheme by adapting its operating parameters to various network deployments and dynamic channel conditions.Then we propose a novel IM scheme,called dynamic interference steering(DIS).By intelligently determining the strength of the steering signal,DIS can steer the interference in an optimal direction to balance the transmitter's power used for steering and the desired signal's transmission.DIS is shown via simulation to be able to make better use of the transmit power,hence enhancing users' spectral efficiency effectively.The first two methods are applied in scenarios where the interference topology is asymmetric,in other words,the steering signal will bring side-effect in the scenarios where the interference topology is symmetric.At last,we take the downlink cellular network using Co MP technology as an example,and propose a new IM technique,called Spatial-and-Power Domain Adaptive Interference Steering(SPAIS).By adjusting the spatial characteristics and power of the steering signal simultaneously,the side effect and benefits of steering signal can be balanced,so higher SE of system can be achieved.At the end of this thesis,we conclude the research work and give directions for the future work.