Research On Distributed Antenna System

To meet the increasing demand for wireless data traffic, multiple antenna technology has been introduced into wireless communication systems. Different with conventional centralized system, the transmit antennas in distributed system are located in different geographic locations, which overcomes the problem of strong channel correlation and greatly shortens the distance between the base stations and the users.Moreover, distributed antenna system can effectively improve the spectral and energy efficiency by cooperative communication technology.However, what limits the development of distributed multiple antennas technology is that it needs additional resources for sharing channel state information, resource allocation and precoding information. Some detailed researches are done on the transceiver antenna selection scheme and resource allocation scheme based on the energy efficiency in distributed antenna system, and the the robustness optimization design under the imperfect channel condition in this paper. The corresponding innovative solutions are proposed. The main contributions and innovative points of this paper are mainly the following three aspects:In the first aspect, how to reduce the energy consumption of wireless communication system and at the same time improve the network energy efficiency has become a hot and difficult issue in the current research. In the first part of this paper, the paper focuses on the system energy efficiency, and studys on the resource allocation problem based on energy efficiency. Fisrtly, under the condition of power constraint and frouthual capacity constraint for each BS, we formulate the energy efficiency maximization of the distributed antenna system under the condition of perfect CSI, and then employ the norm design method, WMMSE and corresponding convex optimization method to solve the problem. Finally,simulation results verify the effectiveness and convergence of the proposed algorithm.In the second aspect, under the rise of green communication, how to improve the spectrum and energy efficiency at the same time of distributed antenna system is an urgent problem. In the second part, we analyzed the transceiver antenna selection strategy in multicell multiuser MIMO system, which can improve the network's energy efficiency.Firstly, we derive the ergodic energy efficiency based on the large scale CSI, and based on the ergodic energy efficiency; we further design the cost function, which can show the value change of network cluster energy efficiency. Finally, we propose an antenna selection algorithm based on the cluster energy efficiency. The algorithm has low complexity without iteration. It can greatly reduce the amount of interaction between the base stations with great anti-jamming ability. The simulation results verify that proposed algorithm can effectively improve the energy efficiency of multi cell network.In the third aspect, most of the existing researches on distributed antenna system are based on the perfect channel conditions. However, in the practical system, due to the estimation error and quantization error,the channel state information (CSI) is often imperfect. In addition, the quality of CSI will be further reduced with the intensive wireless network infrastructure and the application of massive MIMO. Therefore, the performance optimization based on the imperfect channel condition is very necessary. In the third part, the imperfect channel model is given for multi scenarios, including channel estimation error, quantization error,and feedback delay. Based on the model, we propose a robust optimization algorithm, which can ensure fairness of users. This algorithm considers the influence of multi factors on the system performance. It has advantages of a wide range of applications, good convergence and robustness. Finally, we explored the system's performance under different channel conditions by simulation.