EasiARS：多模通信传感网的动态WiFi链路接入及自适应组网方法

在使用WiFi接入上层服务的无线传感器网络应用中，由于WiFi链路的不稳定性，使用固定位置的网关难以适应长期稳定可靠接入的要求.提出一种基于ZigBee和WiFi双模通信节点的，适用于不稳定WiFi链路下的网络设备自适应接入及组网方法EasiARS(adaptive roles switching)，该方法包括实时低开销的WiFi覆盖环境探测和更新方法、节点自适应角色分配方法、网关和节点均为能量受限设备情况下的WiFi覆盖区内分簇和数据传输方法.EasiARS可以在外部WiFi网络环境动态变化的情况下进行传感网设备的快速部署，并根据WiFi链路的状态自适应地调整节点角色和传输策略，使数据稳定传输并均衡WiFi覆盖区内节点的能量消耗.实验验证表明，在WiFi链路状态变化下，使用EasiARS的传感网能够自适应地切换节点的工作角色，形成合适的网络拓扑结构，保证数据的稳定上传，与采用单个固定位置网关的方法比较，随着WiFi链路不同程度的变化，EasiARS的网络丢包率最多可降低90%；与采用多个备选网关的方法比较，使用EasiARS的网络生存期提高了67%，并减少了部署前期对WiFi链路质量测试和评估的工作负担.

EasiARS: Dynamic WiFi Link Access and Adaptive Networking Based on Multi-Mode Communication in Wireless Sensor Networks

In some wireless sensor networks(WSNs) applications, gateway nodes use WiFi to access upper layer network. However, due to the instability of wireless link quality, it has a lot of work to find a stable and reliable gateway disposition by using fixed gateways in traditional WSNs structure. In this paper, we propose a novel method for dynamic WiFi link access and adaptive networking called EasiARS, which is applicable to the scenarios where WiFi link quality is instable and all devices including gateways and nodes are energy constrained. EasiARS is based on WiFi and ZigBee multi-mode communication. It contains a low-overhead real-time WiFi coverage detection method, a roles switching method and a clustering and neworking method in WiFi coverage area. EasiARS makes it feasible to rapidly deploy WSNs systems in dynamic WiFi link environment. While system is working, nodes adjust their roles and transmission strategy according to the WiFi link quality, which ensures WSNs upload data stably and balance the energy consumption in WiFi coverage area. Experiments verify that, EasiARS achieves the purpose that nodes can switch to suitable roles and transmit stably in dynamic WiFi link environment. Compared with single fixed gateway method, EasiARS leads to a reduction up to 90% in packet loss rate under different WiFi link quality, and an improvement of 67% in network lifetime compared with fixed multi-gateway method, meanwhile reduces the burden of WiFi link quality testing and evaluation before deployment.