协作MIMO中分布式空时编码技术的研究

利用单天线终端相互协作，形成虚拟多天线发射阵列，结合接收端基站多天线接收，以此实现协作MIMO系统，同时将MIMO中的空时编码理论应用其中，可以有效利用空间分集增益和编码增益，抵抗多径衰落并提高系统性能。其中，由于分布式空时分组码（D-STBC）能有效地利用空间分集，且编码简单、性能优越，因而重点研究其在协作MIMO中的运用，对其进行了建模，设计了D-STBC接收端检测器结构，指出极大似然（ML）检测的复杂度随协作节点数的增加呈指数增长，并推导了在ML检测下的系统成对差错概率（PEP）性能；同时介绍了基于空间复用的分布式垂直型贝尔实验室分层空时编码（D-VBLAST），它可以有效地提高数据传输速率（吞吐量），且译码算法复杂度可以随着数据速率的增加线性升高，适合于相对较高SNR的协作MIMO传输系统。 

Research of distributed Space-Time Coding techniques in Co-MIMO system

Single-antenna terminals that cooperate with each other could form a virtual multi-antennas array. Combined with the multi-antennas at the receiver (Base Station), it could realize cooperative MIMO system, applying the theory of space-time coding in MIMO system to the cooperative MIMO system in addition, Thus these single terminals could efficiently utilize the spatial-diversity gain and the coding gain in the multi-antenna MIMO systems, which could resist the multi-path fading, and improve the performance. This dissertation emphasizes the D-STBC and D-VBLAST in the cooperative MIMO in detail. Applying D-STBC to the cooperative MIMO, it can efficiently take advantage of the spatial-diversity with easy coding and superior performance, so we study the mathematical model of D-STBC firstly; then design the structure of the detection at the receiver, pointing out the complexity of the ML detection grows exponentially with the increase of cooperative node numbers, and derive the performance of the PEP with the use of ML detection algorithm. We also present the D-VBLAST which is based on the spatial multiplexing. It can efficiently improve the data transmission rate (i.e. throughput capacity), and the complexity of the decoding algorithm grows linearly with the increase of data rate, especially fits to the cooperative MIMO system with higher SNR.