Shangbo Wang

System implementation study on RSSI based positioning in UWB networks

The Ultra-Wideband Radio Technology (UWB-RT) enables accurate Location and Tracking (LT) applications. However, the required and sophisticated time of arrival (ToA) ranging procedure relies on accurate synchronizations and time measurements. Non-cooperative nodes, not supporting the ToA feature, cannot be localized with this LT approach. Other LT approaches exploit the received signal strength (RSS) or received signal strength difference (RSSD). Simulations of RSS based localization in UWB networks showed promising performance results. In this paper, the authors introduce a RSS based LT demonstrator, build up with conventional Certified Wireless USB (CWUSB) sticks, using multiband UWB-RT. Different LT algorithms are tested. In a small UWB network, measurements of the localization accuracy show a root mean square error (RMSE) of about 0.33 meters.

Positioning in multiband OFDM UWB utilizing received signal strength

Ultra-wideband (UWB) enables accurate Localization and Tracking (LT) applications. However, the required and sophisticated time of arrival (ToA) ranging procedure relies on accurate synchronization and time measurements. Today, only few UWB devices support the required ranging feature. Examples are pulse based low data rate (LDR) UWB devices. Conventional multiband OFDM based high data rate (HDR) UWB devices do not support the ToA ranging feature. But the ultra wide frequency bandwidth of UWB enables not only high resolution of space surrounding UWB transceivers and therefore accurate time measurements, its enormous frequency diversity also minimizes fading effects. This allows reliable distance measurements, based on measurements of the received signal strength (RSS). This paper shows, that RSS based localization can be as accurate as ToA based localization. For this purpose, measurement results of the RSS and a derived path-loss model are used to calibrate a Monte Carlo simulator for RSS based ranging and localization. The RSS measurements are done with conventional wireless USB sticks, using HDR UWB. For a small 2 × 2 meters network, the simulation results show mean localization errors between 0.1 and 0.2 meters.

Maximum likelihood localization estimation based on received signal strength

This paper discusses a maximum likelihood (ML) estimator for the localization of mobile nodes in communication networks. The derived estimator is optimized for ranging measurements exploiting the received signal strength (RSS). For this purpose, the bias and uncertainties of the RSS based ranging procedure are analyzed, considering a path loss model of an indoor ultra-wideband (UWB) network under line of sight (LOS) conditions. The nonlinearity of the path loss model is first taken into account before the statistics of the observed RSS are approximated by a Taylor sequence of first order. The so found metrics describe a weighted least squares (WLS) method. The metrics of the estimator are analytically derived in closed-form. The performance of the derived estimator is investigated in Monte-Carlo simulations and compared with a simple least squares (LS) method and another method exploiting RSS fingerprints.

A low-cost protocol and application for UWB localization

Range Radio by Advanced Ultra-Wideband Radio Technology, FP7-ICT-215669, www.euwb.eu) project has been an industry-led initiative of twenty-one major industrial and excellent academic organizations from Europe and Israel who have been targeting innovative improvement, adaptation, integration and application of short-range Ultra-Wideband Radio Technology (UWB-RT). EUWB has effectively leveraged and significantly enhanced the scientific knowledge base in the advanced UWB-RT and has provided sophisticated new applications enabled by UWB and highly demanded in several European key industrial sectors such as home entertainment consumer electronics, automotive, public transportation, and heterogeneous cellular networks. It is anticipated that the efficient exploitation of cross-layer functionalities will fertilize the successful application of UWB technology. Within EUWB, major fields of this emerging challenge have been identified, such as the cognitive radio related Detect-And-Avoid (DAA) technology and the localization and tracking (LT) technology. An important aspect is to design an LT protocol. In this manuscript the authors will first illustrate the technical approach of EUWB, giving a brief overview of the project. Then, the authors will propose a novel LT protocol and application. This application is tailored to operate also with UWB devices that do not fully comply with the previously proposed LT schemes which need specific physical and medium access control layer functionalities.

Java implementation of localization and tracking application based on HDR-UWB platform

In recent years extensive research was carried out in order to develop applications for the Ultra-Wideband (UWB) technology and to resolve the practical challenges in implementing an efficient UWB communication system utilizing the UWB impulse radio for precision localization. ToA (Time of Arrival) or TDoA (Time Difference of Arrival) of ranging frame are widely used because ToA and TDoA provide high accuracy due to the high time resolution with high bandwidth of IR-UWB (Impulse Radio - UWB) signal. HDR-UWB (High Data Rate -UWB) uses MB-OFDM (Multi Band - Orthogonal Frequency Division Multiplexing) to transmit signals, which can reach a data rate of 200 Mbit/s. In this paper a Java implementation of an active LT (Localization and Tracking) method based on a HDR-UWB platform is investigated. The hardware is composed of three UWB anchors, one UWB tag and one UWB location coordinator, which is connected to a PC (Personal Computer) or a PDA (Personal Digital Assistant). The Java program, which is hosted on the PC or PDA, is used to instruct the UWB coordinator to send and receive the UWB ranging frame and localize the tag. ToA is used as a ranging parameter in this work to measure the distance between the used UWB anchors and the UWB tag. The most important aspect is to reduce the jitter of ToA caused by CPU processing and the clock drift between UWB anchors and UWB tag. In this paper a 3-way ranging mechanism to minimize the clock drift is deployed. In addition the use of the JPCAP (Java Package for CAPturing) library in Java reduces the jitter of the ToA.

A localization and tracking application for UWB

An increasing demand for applications in the area of Ultra-Wideband Radio Technology led to the EUWB (Coexisting Short Range Radio by Advanced Ultra-Wideband Radio Technology, FP7-ICT-215669, www.euwb.eu) project, which has been started in April 2008. The goal of this industry-led initiative of major industrial and excellent academic organizations is the improvement, integration, and the applications of UltraWideband Radio Technology (UWB-RT). The EUWB project has significantly enhanced the scientific knowledge base in the UWB-RT and has provided sophisticated new applications enabled by UWB and highly demanded in several European key industrial sectors such as home entertainment consumer electronics, automotive, public transportation, and heterogeneous networks. Without a doubt, the efficient exploitation of cross-layer functionalities will lead to successful applications of UWB technologies. Beside the cognitive radio related technology, namely the Detect-And-Avoid (DAA) technology, the localization and tracking (LT) technology is a major aspect of EUWB, in particular the underlying LT protocol. Within the scope of this manuscript, the authors will give a brief overview of EUWB by illustrating its technical approach. Furthermore, the authors will describe a novel LT protocol as well as its application to a typical scenario. This application is tailored to operate also with UWB devices that do not fully comply with the previously proposed LT schemes which need specific physical and medium access control layer functionalities.

Cognitive Radio Prototyping

Future wireless systems have been evolving toward a broadband and open architecture for efficient multi-service operation, which will have a great impact on the terminal and infrastructure component design methodology for supporting multiple radio schemes. Cooperation in wireless networks, requiring cognitive radio implementations, will facilitate a new dimension in the evolution of multimedia communications. The growing price pressure requires ever increasing high levels of integration efficiency, of flexibility and of future proofness at the same time, setting out in the digital baseband domain. In this communication, the authors will illustrate a platform based prototyping process, setting out from the paradigm developed in the IST-27960 STREP URANUS (UNIVERSAL RADIO-LINK PLATFORM FOR EFFICIENT USER-CENTRIC ACCESS). URANUS investigates the design of a universal radio link platform able to be incorporated in any existing proprietary and standardized wireless system in a seamless way, to ease the introduction of future personalized communications and reconfigurable air interfaces.

A low-cost protocol and application for UWB localization, exploiting cross-layer design and cognitive radio aspects

The EUWB (Coexisting Short Range Radio by Advanced Ultra-Wideband Radio Technology, FP7-ICT-215669, www.euwb.eu) project has been an industry-led initiative of twenty-one major industrial and excellent academic organizations from Europe and Israel targeting innovative improvement, adaptation, integration and application of short-range Ultra-Wideband Radio Technology (UWB-RT). Started in April 2008, the EUWB project has leveraged and enhanced the scientific knowledge base in the advanced UWB-RT and has provided sophisticated new applications enabled by UWB and highly demanded in several European key industrial sectors such as home entertainment consumer electronics, automotive, public transportation, and heterogeneous cellular networks. Within EUWB, major fields of this emerging challenge have been identified, such as the cognitive radio related Detect-And-Avoid (DAA) technology and the localization and tracking (LT) technology. An important aspect is to design an LT protocol. In this manuscript the authors will first illustrate the technical approach of EUWB, giving a brief overview of the project.

Analysis of combined ultra-wideband systems

Ultra-wideband (UWB) radio technology offers a variety of opportunities to fulfill the increasing demands on wireless communication systems. On the one hand, high-speed data transmission can be realized using high data rate (HDR) UWB devices. On the other hand, low-power, low data rate (LDR) devices based on impulse radio can be realized. In this manuscript, the authors present a concept of combining the advantages of both HDR and LDR devices. To reduce the overall power consumption, an HDR can use the LDR physical layer for the transmission of signaling information. Therefore, an adaption layer is proposed which organizes the cooperation between the HDR and the LDR physical layer. The performance of the combined system is discussed as well.

Quality of service parameters optimization in multi user Ultra Wideband systems

Ultra-Wideband (UWB) networks are expected to support a wide range of communication-intensive, real-time multimedia applications. One of the key issues in UWB networks is optimization of Quality of Service (QoS) parameters. To meet the QoS demands of each UWB user and maximize the overall network throughput, several technical aspects shall be concerned, e.g. physical layer transmission format, multi user access format and routing solution. In this paper, a centralized Ultra-Wideband Impulses Radio (IR-UWB) multi user system which contains one Network Coordinator (NC) is considered. A Successive Maximum Likelihood (SML) receiver is designed and presented. It shows that the novel ML receiver outperforms the rake receiver under the multipath environment. Meanwhile, an Optimal Power Allocation (OPA) under the multi user environment is investigated and compared to Maximum Power Allocation (MPA) mechanisms. Our results show that such OPA can increase the overall network throughput in comparison with MPA.