Performance Analysis Of Multi-user Scheduling Schemes In Mimo Systems

Future wireless communication systems are required to support extreme high speed packet data transmission. Due to the limitation of available spectrum resource, high spectrum efficiency technologies are needed to be explored for different OSI layers. Over last decades, many technologies have been investigated to achieve this target. Multiple-input multiple-output (MIMO) system and channel-aware scheduling are two promising schemes proposed for that achievement.In this thesis, we investigate the MIMO impact in increasing the system throughput of next generation mobile wireless systems when transmitting on different channels for several transmission modes. A cross-layer approach in resource allocation and scheduling schemes is considered. The gap between the physical-layer issues such as MIMO gains, Adaptive Modulation and Coding (AMC) and system-level issues focusing more on MAC layer such as scheduling is still significant, in many literature, making the optimal design of resource allocation and scheduling by a cross-layer approach in MIMO-OFDMA systems a challenging task. In being deeply convinced that mathematics is the key technology to cope with central technical problems in the design of wireless networks since the complexity of the problem simply precludes the use of engineering common sense alone to identify good solutions, we explore the benefit of Convex Optimization in Multi antenna systems and resource allocation problems to joint optimize the performance of wireless networks with MIMO links, on the MAC/Link and PHY layers.Different packet scheduling algorithms have different impacts on the performance of systems with MIMO links in terms of throughput, fairness, packet delay, packet loss, etc. We evaluate the performance of scheduling schemes in a Downlink shared channel of 3GPP LTE SISO and MIMO networks using Open Loop Spatial Multiplexing and Transmission Diversity transmit modes. The analysis of UE throughput, fairness, assigned resource blocks, cell throughput, assigned TB CQI, all in one cell are provided. In addition, in the Closed-loop spatial multiplexing transmission mode, a mutual information based Calculation of the Precoding Matrix Indicator, one of the feedback values required at the receiver by 3GPP UMTS Long Term Evolution to perform channel adaption, is evaluated. We also present the performance of channel estimators for LTE, necessary for coherent detection, which will be used by every LTE device. The estimators are compared by means of the throughput, which allows observing influence of an estimator on the complete system. We emphasize on channel estimators for rapidly changing channels. The main goal of this thesis is to provide results that will help in the design process of next generation mobile systems with MIMO links, especially LTE, aiming to get better throughput and fairness for the users.