CrossTrace: Cross-Layer Measurement for IEEE 802.11 Wireless Testbeds

In this paper, we introduce and evaluate CrossTrace, a framework for performing cross-layer measurements in IEEE 802.11 based wireless networks. CrossTrace allows tracing of parameters at MAC-, routing and transport layer in a controlled environment and in a repeatable manner. Using CrossTrace, we conduct a comprehensive measurement study in a miniaturized testbed, in which we analyze the behavior of the IEEE 802.11 MAC-layer with respect to signal strength and bit error rate. We derive the delivery probability and bit error rate dependent on signal strength and MAC-layer datarate with and without interfering background traffic. We show that even moderate background traffic can significantly degrade network performance. Such measurements may help to optimize the orchestration between the different protocol layers and may alleviate the development of new cross-layer designs.