中文摘要：

路由判据对无线Mesh网络（WMN）的性能至关重要，针对期望传输次数（ETX）和期望传输时间（ETT）没有考虑到802．11MAC层的指数回退策略，不能准确评估数据包的平均传输时间问题，提出基于可用传输时间（ATD的路由度量机制．在Linnux平台上对OLSR协议进行扩展，把ATT路由判据与ETX和ETT进行实现测试比较，证明了ATT能使系统性能得到明显提高，更加适用于WMN．

英文摘要：

Routing metric is critical for performance of wireless mesh networks （WMN）. Without considering back-off scheme of IEEES02.11 in Mac layer, expected transmission count （ETX） and expected transmission time （ETT） can not evaluate the average transmission time accurately. A new available transmission time routing metric is proposed based on IEEE 802.11 DCF. We also extend OLSR protocol on Linux platform, and compare ATT with ETX and ETT. The obtained results show that the ATT metric has the lowest packet loss rate and the lowest jitter rate among the analyzed metrics, because it concerns available link bandwidth and also takes physical transmission rates into account.