大规模MIMO通信系统中信号干扰抑制及系统性能研究

发布时间：2018-01-05 23:19

本文关键词：大规模MIMO通信系统中信号干扰抑制及系统性能研究　出处：《北京交通大学》2017年博士论文　论文类型：学位论文

【摘要】：无线通信数据量的爆炸式增长和无线连接数量的极度增加,使得频谱资源的有限性和人们对无线通信服务需求之间的矛盾越发突出。在此背景下,大规模MIMO技术在2010年被Thomas.L.Marzetta等人提出后受到广泛关注。前期研究证实该技术通过充分挖掘空间自由度能够极大地提升频谱资源的利用效率,与此同时在能量效率方面和当前无线通信系统相比也存在几个量级的提升空间。因此,大规模MIMO技术成为第五代(5G,the Fifth Generation)移动通信系统中具有潜力的备选技术之一。但是,大规模MIMO多小区系统中小区间导频信号的干扰成为系统性能提升的瓶颈。因此,本文主要研究大规模MIMO多小区系统中导频信号干扰减轻问题,并提出几种抑制导频污染的方案,以期提升大规模MIMO系统的性能。本文主要的研究工作从以下方面展开:1.基于"注水算法"原理的导频智能分配方案大规模MIMO系统中用于信道估计的正交导频的数量受限于信道的相干时长。同一组正交导频在所有小区间的复用造成复用导频之间的信号干扰,即导频污染。该问题成为大规模MIMO多小区系统性能提升的瓶颈。然而,不同终端对应信道的通信质量是不同的,不同的导频受相邻小区中复用导频的干扰程度也存在差异。因此,本文提出一种基于"注水算法"思想的导频智能分配方案。根据终端信道质量和导频受干扰的程度将导频和终端按"注水算法"思想进行智能配对,达到减轻整个系统导频污染、优化导频资源利用率的目的。实验证明,此方案在牺牲少数信道质量极差终端性能的情况下,极大提升了系统整体的数据容量。2.基于粒子群优化算法的导频智能快速分配方案大规模MIMO多小区系统中导频智能分配方案能够有效的抑制系统整体的导频污染。但是,导频智能分配的运算复杂度与终端数量正相关。例如,10个终端10个正交导频的情况下,终端和导频的配对方案多达10!=3 628 800种。为了降低导频智能分配方案的运算复杂度,本文提出一种基于粒子群优化算法的智能导频快速分配方案。利用粒子群优化算法进行导频智能寻优分配过程中所有粒子之间信息即时共享的特性,有助于快速寻找到终端和导频之间最佳的配对方案,在降低导频智能分配过程运算复杂度的同时减轻系统的导频污染。实验结果证明此方案在抑制导频污染和降低导频智能分配过程中运算复杂度方面的有效性。3.基于终端分层及层间导频异步发送的方案相邻小区间复用导频导致的导频污染对小区中心处终端和边缘处终端的影响是不同的。基于此本文提出一种终端分层小区间边缘终端簇导频异步发送的方案。在此方案中将终端分层,各小区内受干扰程度小的中心终端簇同时发送上行导频,而不同小区内受导频污染严重的边缘终端簇在互不重叠的时隙内发送上行导频。实验证明,该方案可以有效的减轻导频污染对整个系统的影响。但是此方案中存在一个小区内的边缘终端与相邻小区内中心终端复用导频的情况,因此不同小区内边缘终端簇和中心终端簇之间仍然存在导频干扰。为了减轻此部分导频污染,本文又提出一种改进的终端分层及不同终端簇上行导频、下行数据对齐发送的方案。利用上行导频与下行数据之间不相关的特性,通过不同终端簇间上行导频、下行数据交叉发送的方式,导频污染可以得到进一步减轻。实验证实改进的方案比前一种方案在减轻导频污染提高系统性能方面更有优势。4.基于小区分簇导频异步发送及导频功率控制的方案对大规模MIMO多小区系统的小区进行分簇,不同小区分簇内终端以异步的方式轮流发送上行导频。此方案通过将导频污染压缩到同分簇内部小区之间达到减轻整个系统导频污染的目的。显然,小区分簇数量越多导频污染的影响就越小,但是分簇越多一个相干时长内上行数据的发送时间就越被压缩,所以并非小区分簇数量越多系统的整体性能就越好。合理的小区分簇策略对于此方案性能的发挥是至关重要的。本文从上行和下行综合角度考虑有效数据的发送并得到合适的小区分簇策略,从而在减轻导频污染和提升系统整体性能两个方面找到平衡点。实验证实了理论得出的最佳小区分簇因子的有效性。另外,由于此方案中同分簇内部小区之间仍然存在导频污染问题,本文将导频发送功率控制引入到小区分簇导频异步发送方案中,通过控制导频发送功率从而减轻小区分簇内部各小区之间的导频污染,实验仿真证明了该方案在减轻导频污染方面的优势。
[Abstract]:The explosive growth of wireless communication data and wireless connection number increasing, the limited spectrum resources and people become more and more prominent contradictions between the demand of wireless communication services. Under this background, large-scale MIMO technology was proposed by Thomas.L.Marzetta received extensive attention in 2010. Previous studies demonstrated that the technique by exploiting the spatial degrees of freedom can greatly improve the utilization efficiency of spectrum resources, at the same time there are several orders of magnitude compared to improve the energy efficiency of the wireless communication system. Therefore, the large-scale MIMO technology to become the fifth generation (5G the, Fifth Generation) is one of the alternative technology has the potential of mobile communication system. However, large scale MIMO system in small and medium sized multi cell interference the interval of the pilot signal has become the bottleneck of system performance improvement. Therefore, this paper mainly studies the small scale MIMO To alleviate the problem of pilot frequency signal interference system, and puts forward several pilot pollution plan, in order to improve the performance of large scale MIMO system. The main work of this paper from the following aspects: 1. based on the "pilot scheme of intelligent allocation of water filling algorithm" principle in the large scale MIMO system for a limited number of orthogonal pilot channel estimation the channel coherence length. The same set of orthogonal pilot frequency multiplexing in all the inter cell interference between signals caused by complex pilot, pilot pollution. This problem has become a large-scale multi cell MIMO to enhance the system performance bottleneck. However, the quality of different communication terminal corresponding channel is different, different pilot the degree of interference with neighboring cells in the pilot are also different. Therefore, this paper puts forward a based on the "water filling algorithm" thinking of the pilot program. According to the intelligent distribution terminal channel quality and pilot subject The degree of disturbance and pilot terminal according to the "water filling algorithm" thought of intelligent matching, to reduce the whole system pilot pollution, optimize the pilot resource utilization. Experiments show that this scheme at the expense of minority and poor quality of channel terminal performance situation, greatly enhance the data capacity of the overall.2. system fast allocation scheme pilot Intelligent Particle Swarm Optimization Algorithm for large scale MIMO in multi cell system intelligent frequency allocation scheme can effectively suppress the system pilot pollution based on the whole. However, the pilot intelligent allocation of computational complexity and the number of terminals are related. For example, the 10 terminal 10 orthogonal pilot case, and terminal matching program the pilot as many as 10! 628800 =3. In order to reduce the pilot intelligent allocation scheme of computational complexity, this paper proposes an intelligent particle swarm optimization algorithm based on pilot fast allocation scheme. Using particle The characteristics of information sharing between the instant all particle swarm optimization algorithm for pilot intelligent optimization in the distribution process, helps to quickly find the best match for terminal and guide in the pilot frequency between, reduce the computational complexity of the intelligent distribution process and pilot pollution reduce the dye. The experimental results show the effectiveness of.3. scheme in suppressing the pilot pollution and to reduce the computational intelligence pilot allocation process complexity of the pilot scheme of pollution layer stratification and the adjacent cell terminal pilot sent asynchronously between the multiplexed pilot LED based on the impact on the terminal area at the center and the edge of the terminal is different. This paper proposes a hierarchical terminal the inter cell edge terminal cluster pilot scheme based on asynchronous transmission. In this scheme, the terminal layer, each district center and terminal cluster interference degree small transmit uplink pilot, and different In the area by the guide edge of the terminal cluster frequency pollution serious frequency sends the uplink slots in non overlapping. Experiments show that this scheme can effectively reduce the influence of the pilot pollution of the entire system. But the existing edge terminal and the adjacent cell within a cell in the center terminal multiplexing pilot of this scheme therefore, between different areas within the cluster and the cluster center edge terminal terminal still exists pilot interference. In order to reduce the pilot pollution, this paper proposed an improved hierarchical terminal and different terminal cluster uplink pilot downlink data transmission alignment in the case. No related characteristics between using uplink pilot and downlink the data, through different terminal clusters uplink pilot downlink data transmission cross way, pilot pollution can be further reduced. Experiments prove that the improved scheme is a scheme to reduce pilot pollution and improve the system The system performance is more advantageous.4. cell clustering and asynchronous transmission pilot pilot power control scheme for large scale MIMO system based on multi cell cell cluster, different cell cluster terminal asynchronously turns to transmit uplink pilot. This scheme through the pilot pollution pressure reduced to between cluster area to reduce the whole system of pilot pollution. Obviously, affecting cell cluster number of pilot pollution is smaller, but more time to send a coherent cluster within the time length of uplink data is compressed, so the overall performance is not the small number of clusters more system play a reasonable better. Cell clustering strategy for this scheme is essential. This paper from the upstream and downstream comprehensive consideration to send effective data and obtain the suitable cell clustering strategy, in order to reduce pilot pollution and Two aspects to enhance the overall performance of the system to find a balance point. Experiment proves the effectiveness of the best cell theory to find the clustering factor. In addition, the pilot pollution problem still exists between this scheme in the same cluster area, the pilot transmission power control is introduced into the cell cluster pilot asynchronous transmission scheme. Through the pilot pollution control pilot transmission power so as to reduce the area between each cell cluster, simulation experiments show that the scheme to reduce pilot pollution advantages.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN919.3

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