Round-Trip Delay Ranging with Orthogonal Frequency Division Multiplex Signals

Abstract

Location information is a key element for many applications, such as seamless pedestrian navigation in outdoor and indoor environments, and reconnaissance and surveillance based on wireless sensor networks. Global Navigation Satellite Systems enable localization in open areas and are complemented by terrestrial wireless technologies, such as 3GPP-LTE or WiFi, to enable ubiquitous navigation. However, communication in cellular terrestrial wireless systems predominantly occurs in non-line-of-sight conditions between a transmitter and a receiver, which is a major challenge for accurate localization. Future technologies such as (semi)autonomous robotic swarms for exploration in remote environments demand infrastructure-free location information. A radio link among mobile users for joint ranging and communication enables cooperative localization and enables infrastructure-free relative localization for wireless sensor networks. Ranging is referred to as est imation of the distance between a transmitter and a receiver using radio signals, taking advantage of a distance dependent parameter of the radio link, such as the propagation delay. This thesis addresses propagation delay based ranging with orthogonal frequency division multiplex (OFDM) signals for unsynchronized nodes in a cooperative wireless sensor network. Scalability of the ranging technique towards a large number of wireless nodes is addressed. Developed experimental test-beds and elaborate measurement campaigns in outdoor and indoor environments complement the theoretical investigations.