【作者】 马计；

【导师】 魏急波；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2011， 硕士

【摘要】 协同通信系统中各相邻节点以协作的方式共享中继的多根天线,构成虚拟的天线阵列,可以有效的克服无线信道对信号的衰落作用,获得了分集增益和复用增益,提高了通信系统的传输速率和可靠性能。但是传统的基于空时编码的协同系统在实际通信中的协议过程过于复杂,不仅需要中心节点给各中继节点指定具体的矩阵发送形式,而且需要中继节点的选择以获得较好的通信质量。循环延迟分集技术以其实现简单、编码速率高、无需改变现有接收机结构等优点,已被LTE-Advanced选作一种物理层传输技术。基于循环延迟分集技术的协同通信不仅简化了传统协同通信中复杂的协议过程,而且各个中继节点都可以在任意的信道环境中以静默的方式加入到协同过程,硬件上也易于实现。本文围绕基于循环延迟分集技术的协同通信中的关键技术进行了分析和研究。主要研究内容如下:1.在介绍循环延迟分集原理的基础上,具体分析了循环延迟分集的系统模型、循环延迟分集的引入对信道和信号的影响以及循环延迟量的选取对性能的影响。然后基于对前人工作的总结,提出了一种改进的循环延迟量的选取方法,该方法不需要判断发送天线序号。最后把循环延迟分集应用在MIMO-OFDM系统中,并与传统的STBC-OFDM进行了性能仿真以及分析比较。2.分析了基于循环延迟分集的协同通信系统的模型,在介绍了多径信道对协同CDD信号影响的基础上,首先仿真了一种适合CDD传输的信道估计算法,然后在此基础上进行了改进,并分别在非协同和协同场景下进行仿真,可以看出该算法对于残余频偏具有良好的鲁棒性。3.仿真了多频偏对协同CDD性能的影响,然后基于非反馈的系统模型,把OSPIC检测算法和迭代干扰抵消检测算法应用在协同CDD信号检测中,最后针对实际场景进行仿真和算法的复杂度分析。4.研究了时变循环延迟分集(Time Varying Cyclic Delay Diversity, TV-CDD)技术,并把TV-CDD应用在协同通信中,设计了实用的仿真平台,针对不同应用场景对协同系统性能进行了仿真验证工作。更多还原

【Abstract】 By sharing antennas of neighboring nodes in a cooperative manner to construct a virtual environment, cooperative communication systems can combat the signal fading caused by wireless channels effectively. The single-antenna based cooperative system acquires spatial diversity gain and multiplexing gain, as well as the transmission efficiency and reliability. The traditional Space-Time Coding based cooperative communication systems can not be widely applied in the existing point-to-point scenarios since its complex protocol for that the concrete sending matrix has to be assigned in every relay, but also the allocation of the relays for a better environment for communication. Cyclic Delay Diversity (CDD) has been adopted as a basic method for physical layer in LTE-Advanced owing to its simplicity in application, efficient coding ratio and conformable for the existing communication systems. In CDD based cooperative communication, the complex protocol can be avoided and the relays can join in the cooperative process in the manner of silence under any channel environment.The object of this thesis is to have a research on the key technologies for the CDD based cooperative communications. The main subjects investigated are as follows:1. On the basis of introducing the principle of CDD, the system model of CDD and its affect on the channel and the signal is analyzed briefly. After summarizing the existing choosing method for the cyclic shift, a measure that independent of the sending antenna index is proposed. Then we apply the CDD to MIMO-OFDM systems and compare it with the traditional STBC-OFDM system.2. CDD based cooperative communication system model is discussed subsequently. The influence of multi-path channel on the CDD signal is introduced, and then the Winner Filter based channel estimation mechanism is proposed after the simulation and betterment of the estimation method suitable for CDD based transmission. After that we simulate the proposed algorithm under the circumstances of traditional scenario and the cooperative one, which prove the superiority of the algorithm in its robustness to CFOs.3. The influence of multiple Carrier Frequency Offsets (CFOs) on the system performance is investigated. Subsequently based on the model of none-feedback, we propose the signal detection algorithms, Ordered Successive Paralleled Interference Cancellation (OSPIC) and Iterative Interference Cancellation (IIC) under the scenario of cooperative communication; afterwards we simulate the detection algorithm in practical environment and have a research on the complexity.4. Time Varying Cyclic Delay Diversity (TV-CDD) is discussed, and then we apply the Time Varying Cyclic Delay Diversity (TV-CDD) to cooperative communication under the circumstance of frequency selective channels, we design the practical simulation platform and simulate different parameters for practical scenarios.更多还原