Field measurements of 802.11 collision, noise and hidden-node loss rates

In this paper we present the first field measurements taken using a new approach proposed for measuring link impairments in 802.11 WLANs. This uses a sender-side MAC/PHY cross-layer technique that can be implemented on standard hardware and is able to explicitly classify lost transmission opportunities into noise-related losses, collision induced losses, hidden-node losses and to distinguish among these different types of impairments on a per-link basis. We show that potential benefits arising from the availability of accurate and reliable data are considerable.

I. Introduction

In 802.11 there are a variety of reasons why a packet can fail to be transmitted successfully including collisions, hidden nodes, weak signal strength, etc. However, feedback to the sender of a frame is limited to the presence or absence of an acknowledgement. This limited feedback makes schemes for understanding the of the 802.11 channel particularly interesting; information on the cause of failed transmission is required to effectively adapt to the environment.