在无线局域网中,接入点(access point,简称AP)的稠密部署使得AP的关联策略成为一个重要的研究问题.目前,用户与AP的关联仅依据AP的信号强度,然而,这种方法未能考虑到网络中AP的异构性,以及不同用户对资源(例如带宽、安全性、时延等)的不同需求,并且分布式的AP关联会造成网络中AP负载的不均衡.针对以上问题,基于软件定义网络(software defined network,简称SDN)技术提出一种集中式的AP关联策略模型.该模型同时考虑了网络管理员和用户的目标,对网络负载均衡和用户资源满足度同时进行优化.采用蚁群算法对模型进行求解,并通过仿真实验对算法进行验证.实验结果表明,针对随机生成的数据集,用户资源满足度可由54.5%分别提升至86.8%(重负载时)和94.1%(轻负载时),并且管理员目标(负载均衡)得到了明显的改善.

The dense deployment of wireless access points (APs) makes AP association an important problem. Currently, AP association is solely based on the signal levels of APs. However, this approach fails to consider the heterogeneous nature of APs, and the variety of user demands (bandwidth, security, delay, etc). In addition, distributed AP association cannot achieve network-level load balance. To address the issue, this paper proposes a centralized AP association model based on the software defined network (SDN). This model considers the objective of network administrator and wireless clients simultaneously, and can optimize the load balance of APs as well as satisfactory of clients. Ant colony algorithm is used to solve the model, and simulation is performed to validate the algorithm. Results show that user satisfactory factor as defined in our model increases from 54.5% to 86.8% under heavy load, and to 94.1% under light load. In addition, the load balance of APs also improves remarkably.

国家自然科学基金(61272459, 61170245, 61221063, 61402357);国家高技术研究发展计划(863)(2013AA013501);工信部重大专项(2013ZX03002003-004);陕西省工业攻关计划(2013K06-38);中央高校基本科研业务费