Multi-Tier User Oriented Antenna Selection In Multiuser Massive MIMO

An increasing number of researchers consider that massive multiple-input multiple-output(MIMO)will probably play an important role in the fifth-generation(5G)wireless networks due to its capability of improving the system's achievable throughput and overall date rates,and also increasing communication reliability and/or bandwidth efficiency without requiring extra bandwidth and power consumption.However,these performance improvements are based on employing multiple radio-frequency(RF)chains,resulting in higher power consumption and hardware costs in massive MIMO systems.Antenna selection(AS)offers a low-cost,low-complexity technique of utilizing a limited number of RF chains,while retaining the significant advantages of MIMO systems and significantly outperforming the conventional MIMO systems operating without adopting AS.In this thesis,two AS aided multiuser massive MIMO systems are proposed for operating in the MIMO downlink channel environments,which are capable of providing different level quality-of-services(QoS)to users according their different requirement,and the main ideas are to carry out AS based on the QoS requirements of different users.Firstly,the research background and significance of multiuser massive MIMO are introduced.Then the challenges of massive MIMO systems and the necessity of AS for massive MIMO systems will be analyzed.For the sake of reducing the decoding complexity at users' side,we opt for employing a simple yet efficient zero-forcing beamforming(ZFBF)linear precoding scheme at the transmitter.Moreover,The AS system performance and user QoS are analyzed by varying the signal noise ratio(SNR),the number of antennas,of RF chains and of users.Additionally,we proposed a novel two-tier user-oriented AS scheme,of which is capable of offering higher QoS for priority users,while reasonably ensuring the performance of the common users requiring lower QoS.The main idea is to carry out AS based on the QoS requirements of priority users.A novel three-tier user-oriented AS scheme is also proposed,and the AS carried out primarily for first level users and second level users.In this way,ahighest QoS may be ensured for first level users,and a moderate QoS may be achieved for second level users,while common users remain lowest QoS.Moreover,the factors that influence the QoS to users of the proposed two-tier user oriented AS and three-tier user oriented AS systems are analyzed.Furthermore,the proposed schemes are compared to norm-based AS scheme and the conventional multiuser massive MIMO operating without AS.