Measurement and Analysis of Link Quality in Wireless Networks: An Application Perspective

Estimating the quality of wireless link is vital to optimize several protocols and applications in wireless networks. In realistic wireless networks, link quality is generally predicted by measuring received signal strength and error rates. Understanding the temporal properties of these parameters is essential for the measured values to be representative, and for accurate prediction of performance of the system. In this paper, we analyze the received signal strength and error rates in an IEEE 802.11 indoor wireless mesh network, with special focus to understand its utility to measurement based protocols. We show that statistical distribution and memory properties vary across different links, but are predictable. Our experimental measurements also show that, due to the effect of fading, the packet error rates do not always monotonically decrease as the transmission rate is reduced. This has serious implications on many measurement-based protocols such as rate-adaptation algorithms. Finally, we describe real-time measurement framework that enables several applications on wireless testbed, and discuss the results from example applications that utilize measurement of signal strength and error rates.