VHT WLANs多用户MIMO传输时OBSS干扰问题的解决方案研究

交叠的基本业务集 (OBSS，Overlap Basic Service Set)是无线局域网的主要场景，如何有效地满足OBSS站点的QoS要求成为无线局域网的研究重点之一。而被称为新一代Wi-Fi的VHT(Very High Throughput) WLANs多用户MIMO的引入,使得OBSS场景的干扰问题成为亟待解决的对象。本文在VHT WLANs的草案基础上，针对无线局域网OBSS(Overlap Basic Service Set)站点在新型的多用户MIMO(MU-MIMO)传输机制下的干扰问题提出了三种解决方案。第一种是基于站点信道相关性的分组方法，通过分组使各站点信道之间相互正交或近似正交来达到缓解OBSS站点的强干扰问题，从仿真结果可以看到所提方案BER性能上的优越性；第二种方案是针对需满足QoS要求的OBSS站点，在现有协议基础上提出了一种基于波束方向约束的干扰避免方案，使系统“和速率”有较大的提升，所提方案不仅能够基本解决OBSS站点的强干扰问题，而且只需较小的帧结构修改，容易实现；第三种方案则是利用干扰对齐技术，在假定站点可以同时关联多个AP的场景下，对比了采用干扰对齐方案和传统方案时对OBSS站点性能的影响。论文最后通过仿真验证了三种干扰解决方案的正确性和有效性，为新一代Wi-Fi的应用奠定了坚实的基础。 

The Research on Solutions for OBSS Interference Problems in MU-MIMO Transmission Based on VHT WLANs

The OBSS scenario is a primary scenario in WLANs, which becomes a significant problem to be solved especially the introduction of MU-MIMO in VHT WLANs. The paper proposed three solutions to the WLAN OBSS interference problem in MU-MIMO downlink transmission based on the VHT WLANs draft2.0. The first solution mitigates the OBSS interference through grouping, because the lower correlation of users’ channels, the weaker the interference between users when implementing MU-MIMO, we can see that the performance of MU-MIMO after grouping is more superior than the random case; The second solution is a spatial division interference avoidance scheme according to the current protocol in order to satisfy the QoS requirement of OBSS, which can improve the sum rate significantly compared with the traditional schemes and have less modification of frame structure; The third solution assumes the stations located in OBSS can associate with multiple APs and gives the effect of interference alignment scheme on OBSS stations compared with the traditional scheme. Simulations show the effectiveness and performance of the proposed solutions.