On the Cramer-Rao Lower Bounds of Ranging Based on IR-UWB TOA Estimation in Wirelessbody Area Networks

Abstract

Wireless Body Area Networks (WBANs) have been subject to important research efforts for the past years. They are indeed expected to fulfil the needs of a variety of emerging human centric applications at very low cost and ultra-low power (e.g. healthcare, wellness, security, sports, gaming). Even more recently these networks have been considered for radiolocation purposes (i.e. out of transmitted signals on and around the body). This new localization add-on is rather based on the estimation of the separating distance between the WBANs devices, based on radio technologies such as Narrow-Band (N-B) and/or even Impulse Radio-Ultra Wideband (IR-UWB). In this context we present herein a theoretical modeling of WBANs ranging errors based on IR-UWB Time Of Arrival (TOA) estimation. This model consists in applying a Cramer Rao Lower Bound (CRLB) expression for discussions, after extracting realistic Channel Impulse Response (CIR) out of recent UWB multipath channel measurement campaign. The CRLB of any unbiased TOA estimator is computed in the [3.1, 5.1]GHz and [3.75, 4.25]GHz bands. The latter frequency band is compliant with the channel 2 of the IEEE 802.15.4a standard, as well as with one mandatory band imposed by the IEEE 802.15.6 standardization group.