WLAN中多天线异构接入点的并行传输机理研究

To improve the performance of the wireless local access network (WLAN), the 802.11 standards continue to enhance the multiple input multiple output (MIMO) technology. It would be a common scenario that the WLAN is deployed densely with heterogeneous access point supporting different numbers of antennas. However, due to the limitation of the CSMA/CA mechanism of the 802.11 MAC specification, multiple access nodes in the same collision area cannot be transmit data simultaneously. As a result, the network capacity improvement brought by the MIMO cannot be taken use of and the WLAN is in inefficient state. Aiming to improve the efficiency of WLAN, this proposal will investigate the theory of simultaneous transmission of heterogeneous access nodes in WLAN, and achieves the dynamic adjustment of the collision area and simultaneous transmission of multiple access nodes in the same collision area. The major studies include 1) investigate dynamic carrier sensing control model based on the statistical geometry to achieve the area spectral efficiency improvement in the collision area. 2) investigate the simultaneous transmission mechanism for the heterogeneous access points, model and optimize the mechanism based on the Markov chain. 3) investigate the distributed interference cancellation algorithm for the heterogeneous access point in the WLAN, design the demo to verify the algorithm. Based on these studies, we will make a series of innovative achievements in the theory and methods related to the simultaneous transmission of heterogeneous access nodes in WLAN.

为了提升无线局域网的性能，802.11标准不断增强对多天线的支持，由支持不同天线数目的WLAN异构节点密集组网已成为常态。然而802.11MAC层机制存在局限，同一冲突域内多个节点无法并行传输数据，密集组网下节点的多天线带来的容量提升潜力也得不到充分利用，导致了WLAN密集组网的效率低下。本课题从提升WLAN密集组网效率出发，研究多天线异构接入点的并行传输机理，动态调整冲突域尺度并实现同一冲突域多接入点并行传输。研究基于随机几何的动态载波感知控制模型，实现频谱空间复用提升的同时降低域间干扰；研究WLAN中多天线异构接入点并行传输机制，基于马尔科夫链对并行传输机制建模和优化；研究多天线异构接入点分布式干扰消除算法，并搭建原型系统进行验证。项目预期在相关机理研究和方法创新方面取得突破，形成WLAN网络中多天线异构接入点的并行传输理论及机制，提升WLAN组网效率，从而取得相应自主知识产权。

为了满足日益增长的用户需求，WLAN作为蜂窝网络的有效补充被广泛地部署。然而，随着WLAN网络部署的密集化，如何提高WLAN的组网效率成为了亟待解决的问题。.本课题组主要针对WLAN多天线异构接入网络，设计WLAN冲突域内多个节点并行传输的接入机制以及智能算法，突破传统的802.11协议本身的限制，充分利用多天线所来的空间增益，提高WLAN系统的组网效率。课题组对WLAN的媒体接入层进行优化研究，分别对WLAN的二进制退避算法进行改进，实现不同退避阶段的退避区域不相交性，从而极大地减少节点间的碰撞概率；设计WLAN多节点并行传输机制，从时域，频域，空间域三个维度设计WLAN多节点并行传输，有效地提高密集WLAN的组网效率；此外，针对WLAN网络的动态变化环境，研究了基于学习的WLAN管理机制，实现动态载波感知控制、自适应速率选择决策以及按需的信道捆绑技术，实现智能高效的WLAN网络。. 通过大量的仿真实验以及原型系统的搭建，验证了本课题所提出的并行接入机制以及智能算法有效地提高了WLAN的组网效率。