%0 Journal Article
%T Receiver Design for Time-Based Ranging with IEEE 802.11b Signals
%A Reinhard Exel
%J International Journal of Navigation and Observation
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/743625
%X This paper presents a ranging receiver architecture able to timestamp IEEE 802.11b Wireless LAN signals with sub-100 picosecond precision enabling time-based range measurements. Starting from the signal model, the performance of the proposed architecture is assessed in terms of statistical bounds when perturbed by zero-mean additive white Gaussian noise (AWGN) as well as in case of multipath propagation. Results of the proposed architecture, implemented in a Field Programmable Gate Array-(FPGA-) based prototype, are presented for different environments. For AWGN channels, the prototype system is able to attain an accuracy of 1.2£¿cm while the ranging accuracy degrades in dynamic multipath scenarios to about 0.6£¿m for 80% of the measurements due to the limited bandwidth of the signal. 1. Introduction Despite the fact that Global Navigation Satellite Systems (GNSSes) cover nearly 100% of the planet, satellite-based localization is not available within buildings as the roofing and walls deteriorate the signal to a degree where an errorless decoding is no longer possible. Mounting pseudolites, devices transmitting the navigation signals, under the roofs are certainly not a valid solution, not only due to legal restrictions. The differences between indoor and outdoor localization are more substantial than just the received power. Radio propagation within complex environments, typical for indoor scenarios, are challenging for high-speed wireless communication, but even tougher for any form of localization service. Many localization concepts (e.g., based on ultrasonic, electromagnetic waves, inertial sensors) have been proposed to bridge the gap between GNSSes and the lack of indoor locating systems. Nevertheless, for indoor environments, there is still no general satisfactory solution available as different key factors, such as low power consumption and high refreshment rate are incompatible. One major reason why indoor radio localization systems are way behind satellite navigation solutions is that the majority of all current wireless communication standards have not been designed with position determination in mind. These signals are often referred to as Signals of Opportunity (SoO). In theory, adding a localization service upon an existing standard is always possible. However, the key parameters like accuracy, reliability, or cost depend on the restrictions of the wireless standard. As a result, retrofitting a localization service to an existing technology might turn out to be highly complex as, for example, the integration of the Enhanced 911 service into
%U http://www.hindawi.com/journals/ijno/2012/743625/