结合空时分组码和机会调度的多用户MIMO系统容量分析

为了充分利用多用户多输入多输出系统(MU-MIMO)中固有的多用户分集，采用机会调度方案，同时为了有效利用空间分集增益和编码增益，应用空时编码理论抵抗多径衰落和提高系统的性能.在瑞利信道下给出了一种结合空时分组码和机会调度的方案并对其进行了容量分析.基于多项式展开的方法，推导了理想和非理想信道估计时的信道容量的封闭表达式、上界值以及高信噪比和低信噪比时的渐近表达式，并分析了不同信道估计时的容量比.此外，分析了基于空间和多用户分集的遍历容量改善.通过相应的数值计算和蒙塔卡罗仿真很好地验证了理论分析的正确性,并表明：多用户分集提高了该方案的性能，而信道估计误差的存在却引起了信道容量的损失；在不同信噪比区域，遍历容量可用相应的渐近表达式来近似.

Capacity Analysis of Combining Space-Time Block Codes and Opportunistic Scheduling in MU-MIMO Systems

In order to utilize the multiuser diversity efficiently in multiuser MIMO systems，employing opportunistic scheduling(OS) and in the meantime, to utilize the spatial diversity gain and coding gain effectively, the theory of space time block codes(STBC) was applied, which could resist the multi path fading and improve the performance of systems. Thus, a novel scheme that combining STBC and OS was presented and its capacity was analyzed under Rayleigh channels. Through the direct way based on polynomial expansion, ergodic capacity expressions over MIMO Rayleigh channels under perfect and imperfect channel estimation were derived for several cases: the exact closed form, asymptotic expressions for high and low SNR regions, and moreover, the capacity ratio between perfect and imperfect CSI was analyzed. Besides, capacity improvements based on MUD and SD were analyzed. The correctness of theoretical analysis was verified by the corresponding numerical and Monta Carlo simulation results which indicate that the capacity of this scheme is improved by MUD and the capacity loss is caused by channel estimation error, the ergodic capacity can be approximated by corresponding asymptotic expressions in different SNR regions.