Channel Sounding for the Masses: Low Complexity GNU 802.11b Channel Impulse Response Estimation

TL;DR

This paper introduces a low-complexity, software-defined IEEE 802.11b receiver system for measuring channel impulse responses, enabling widespread, inexpensive channel sounding using standard wireless hardware and open-source software.

Contribution

It presents a novel, computationally efficient method for CIR estimation using USRP and GNU Radio, making channel sounding accessible with minimal additional processing.

Findings

Validated the system with extensive urban and suburban drive tests

Achieved high-quality CIR estimation with low computational overhead

Demonstrated feasibility of widespread channel sounding using standard hardware

Abstract

New techniques in cross-layer wireless networks are building demand for ubiquitous channel sounding, that is, the capability to measure channel impulse response (CIR) with any standard wireless network and node. Towards that goal, we present a software-defined IEEE 802.11b receiver and CIR estimation system with little additional computational complexity compared to 802.11b reception alone. The system implementation, using the universal software radio peripheral (USRP) and GNU Radio, is described and compared to previous work. By overcoming computational limitations and performing direct-sequence spread-spectrum (DS-SS) matched filtering on the USRP, we enable high-quality yet inexpensive CIR estimation. We validate the channel sounder and present a drive test campaign which measures hundreds of channels between WiFi access points and an in-vehicle receiver in urban and suburban areas.