cTEx – A Configurable Topology Explorer for Wireless Ad-hoc Networks

High-quality information about the network status is essential for the discovery and operation of routes and clusters in wireless ad-hoc networks. This requires permanent observation and assessment of nodes, links, and link metrics, and the exchange of gathered status data. In this paper, we present cTEx, a configurable topology explorer for wireless ad-hoc networks that efficiently detects and exchanges high-quality network status information during operation. To establish accurate status data about individual links, nodes transmit unicast probe frames with sequence numbers, which are received and processed by neighbors operating in monitor mode. By checking sequence numbers, nodes can detect frame loss without providing feedback to senders, and determine accurate packet delivery ratios for incoming links, serving as a statistical basis for more sophisticated link metrics. Regular unicast frames are also interpreted as probe frames to reduce bandwidth usage. We have implemented cTEx in a Wi-Fi testbed, evaluate its accuracy, status exchange delay, and overhead, and compare it to existing approaches.