【作者】 陈清；

【导师】 方旭明；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2010， 硕士

【摘要】 随着无线通信技术的飞速发展和广泛应用,用户要求大幅度地提高无线通信速率的愿望变得越来越强烈,多输入多输出(Multiple input and Multiple output, MIMO)技术可突破传统无线通信系统的容量界限,在不增加带宽和天线发送功率的情况下,成倍提高频谱利用率。但由于在用户终端(User Equipment, UE)不易配置多根天线,而限制了其在上行方向的应用。虚拟MIMO (Virtual MIMO, VMIMO)系统由多个具有单天线的UE配成一组,占用相同的时／频资源传输信息,从而提高上行系统容量,因此得到广泛关注。而正交频分多址接入(Orthogonal Frequency Division Multiple Access, OFDMA)技术通过为每个用户分配一个(或一组)子载波来实现多址接入,是实现正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)系统中多用户复用和接入的有效方式。将VMIMO和OFDMA技术的优势相结合,非常适合下一代无线通信系统对高速数据传输速率的要求。未来通信网络不仅需要提供更大的系统容量,也要保证高速率、广覆盖的需求。在蜂窝网络现有设施的基础上引入中继(Relay Station, RS)技术,在改善小区边缘用户的服务质量、降低网络投资和运营成本、改善小区覆盖范围等方面发挥着重要作用。因此,本文将VMIMO系统的用户配对调度算法作为本文的研究重点,并考虑其扩展到多跳中继网络中的应用。论文首先介绍了VMIMO-OFDMA系统的基本原理,归纳总结了在该系统下无线资源管理的研究方法,包括用户配对、分组调度、功率控制和自适应技术。然后对VMIMO系统容量进行了分析,并对VMIMO用户配对算法进行了广泛深入的研究。搭建了VMIMO-OFDMA系统仿真平台,对现有基本的用户配对算法,如随机配对算法、正交配对算法、行列式配对算法、自适应行列式配对算法进行了分析和性能仿真评价。通过深入研究,基于传统的配对算法无法兼顾到配对用户间远近效应与系统吞吐量问题,本文提出了一种基于信噪比(Signal to Noise Ratio, SNR)门限融合比例公平调度算法的上行VMIMO配对方案。仿真结果表明,本文所提算法在保证低SNR用户服务质量的基础上提高了系统吞吐量,同时可以降低对相邻小区的干扰,减小系统丢包率,更适合实际系统的应用。其次,考虑到低SNR用户(如小区边缘用户)采用基于SNR门限的用户配对算法不能提高吞吐量,将VMIMO配对算法扩展到中继网络,提出了一种基于协作增益的VMIMO中继系统协作配对策略。通过理论分析和仿真,得出该算法不仅提高了小区边缘用户的吞吐量,降低了对相邻小区用户的干扰,更进一步提高了上行系统容量。更多还原

【Abstract】 With the rapid development and the widely application of wireless communication, the desire for users to largely improve the transmission rate of wireless communication is getting much stronger than ever before. Multiple Input and Multiple Output (MIMO) technology can break through the traditional capacity limits of wireless communication systems. The spectrum efficiency can be greatly improved by setting multiple antennas without increasing the required bandwidth and transmitting power. However, it is not easy to design multiple antennas in a user equipment (UE), which limits its application in the uplink transmission, In the virtual MIMO (VMIMO) concept, multiple single-antenna UEs can be grouped together to transmit signals at the same time/frequency resources to improve the uplink system capacity. Therefore, it attracts the most attention. By allocating each user one or a group of subcarriers to realize multiple access scheme, Orthogonal Frequency Division Multiple Access (OFDMA) is the most effective way to realize multiuser multiplexing and access in Orthogonal Frequency Division Multiplexing (OFDM) systems. The combination of the advantages of VMIMO and OFDMA technique is suitable for the high data rate transmission for the next wireless communication systems.Future communication networks not only provide greater system capacity, but also ensure the needs of high-speed and wide coverage. The introduction of relay station (RS) technology to the current cellular system, can improve the cell-edge users’QoS, reduce the network investment and operation cost. And it also plays an important role in enhancing the system coverage. Therefore, the objective of this thesis is to investigate the user pairing scheduling algorithms for VMIMO system, and consider its extending applications in multi-hop relay networks.In this thesis, the principles of VMIMO-OFDMA are introduced firstly, and then the methods to research radio resource management, especially the user pairing algorithms are investigated in details. The simulation platform for VMIMO-OFDMA system is built up. Then several typical user pairing algorithms in single-hop, such as random pairing algorithm, orthogonal pairing algorithm, determinant pairing algorithm and adjustable determinant pairing algorithm are investigated and simulated to compare the algorithms’performance. Considering the traditional pairing algorithms which can’t achieve the tradeoff between paired users’near far effect and system throughput, we propose a novel pairing scheduling scheme based on the SNR threshold combined with the proportional fair scheduling scheme. Simulation results show that the proposed scheme improves the system capacity without reducing the QoS for the users at the cell’s edge. Meanwhile, it also reduces the interference of the adjacent cells and system lose rate. Therefore, it is suitable for the real system applications.Secondly, due to the user which has lower SNR (such as the user at the cell’s edge) can’t achieve high throughput, in this thesis, by analyzing the existed pairing algorithms, we consider the determinant pairing scheme for the relay system, and propose a cooperative relay pairing algorithm. Simulation results show that our algorithm can provide higher throughput for the user at the cell’s edge compared to the traditional pairing algorithms and it also reduce the interference of the adjacent cells and gain more uplink system capacity.更多还原