Wireless local positioning system

A method of locating mobiles via a dynamic base station. The method includes transmitting a first wireless signal from the dynamic base station at a first time, and receiving the first wireless signal at the mobile. The method also includes transmitting a second wireless signal from the mobile in response to receiving the first wireless signal, and receiving the second wireless signal at the dynamic base station at a second time. The method also includes determining a time difference between the first time and the second time, determining an angle of arrival of the second wireless signal, and locating the mobile based on the angle of arrival and the time difference.https://digitalcommons.mtu.edu/patents/1028/thumbnail.jp

An Introduction to the Fundamentals and Implementation of Wireless Local Positioning Systems

A wireless local positioning system (WLPS) is an active remote positioning system. This chapter discusses the details and the implementation of the WLPS. WLPS is a positioning system that functions in global positioning system (GPS)-denied environments and/or when the GPS is jammed. It allows single-node localization through round-trip time-of-arrival (TOA) estimation and direction-of-arrival (DOA) estimation via antenna arrays. It is a critical localization technique for urban and indoor areas. The chapter explains the implementation of WLPS via direct-sequence code division multiple access (DS-CDMA) system. DS-CDMA systems allow high-performance detection and localization in urban areas by exploiting path diversity. In addition, the chapter describes the implementation of beamforming (BF) and DOA techniques via WLPS antenna arrays. Finally, it discusses the design stages of WLPS systems. This discussion provides designers with a good example of the design stages of a radio prototype

An Introduction to Direction-of-Arrival Estimation Techniques via Antenna Arrays

This chapter introduces the fundamentals of direction-of-arrival (DOA) estimation techniques for localization systems. The main goal is the introduction of DOA methods via antenna arrays. In order to better introduce the principles of DOA, the chapter first briefly explains antenna systems and antenna arrays. It describes important parameters of an antenna and antenna arrays and the notion of beamforming (BF). The chapter explains different measures for comparing DOA estimation methods and examples of DOA estimation techniques, and discusses their pros and cons. Moreover, it introduces a new DOA estimation method that improves the performance and complexity for implementation on software-defined radios. Finally, the chapter discusses a DOA estimation method that is suitable for periodic sense transmissions in localization techniques such as wireless local positioning systems (WLPSs)

Channel Modeling and Its Impact on Localization

Recent advances in wireless sensor networks (WSN) and wireless localization have enabled their applications in a range of systems from autonomous collision avoidance to multirobot collaboration in support of search and rescue operations. This chapter reviews concepts and models of wireless channels that are critical to the localization systems. It discusses the general concept of the impact of channel modeling on the design of radio systems. In addition, the chapter investigates important channel parameters for different localization techniques such as received signal strength (RSS). It also discusses channel parameters essential to position location methods such as time of arrival (TOA) and direction of arrival (DOA), and line-of-sight (LOS) and non-line-of-sight (NLOS) localization

Traffic pattern prediction and performance investigation for cognitive radio systems

In this paper, we propose a technique for predicting the traffic pattern of primary users in cognitive radio systems. Cognitive radios enable sharing the frequency bands that are licensed to primary users. By forecasting the traffic pattern of primary users, secondary users can estimate the utilization of frequency bands and select one for radio transmission to reduce the frequency hopping rate (the rate of switching from one frequency band to another) and the interference effects, while maintaining a reasonable blocking rate. In this work, we propose an algorithm for the prediction of call arrival rate which exploits the periodicity of the traffic process. In addition, we present an approach for call holding time estimation. The results are incorporated to evaluate the probability of the availability of a frequency band within a time period. Setting a threshold on this probability maintains a tradeoff between the blocking rate of secondary users, interference effects on primary users and spectrum efficiency. Simulations are conducted to investigate the performance of cognitive radio systems with and without traffic prediction. © 2008 IEEE

Inter-vendor dynamic spectrum sharing: Feasibility study and performance evaluation

This paper introduces a dynamic spectrum sharing scheme applied across vendors (service providers such as wireless companies). A spectrum allocation server (SAS) equipped with cognitive radio senses the surrounding environment and acquires spectrum utilization information in its coverage area. Upon request, the SAS allocates the available spectrum to the overloaded vendors. The paper mainly studies the feasibility of the proposed technique in terms of the probability-of-sharing across vendors, and analyzes the impact of correlation of traffic rates on the performance of inter-vendor spectrum sharing. © 2007 IEEE

High-resolution low-complexity cognitive-radio-based multiband range estimation: Concatenated spectrum vs. fusion-based

This paper, incorporating the principles of cognitive radios and utilizing the available bandwidth, proposes an active range estimation method with the properties of high precision and low complexity in wireless environments. Here, the cognitive radio concatenates the available narrow-band white spaces to increase the precision of a range estimation system. Two scenarios are investigated. First, signals are transmitted over an available spectrum either simultaneously (parallel concatenation) or sequentially (serial concatenation). Low complexity radio designs that handle the concatenation process sequentially and in parallel are introduced. To improve the range estimation performance, two new high-resolution time-of-arrival (TOA) estimation algorithms that are applicable to multiband scenarios are investigated. The first algorithm estimates the TOA over each subband and then optimally fuses the estimated TOAs. In the second technique, channels estimated over subbands are concatenated and a TOA estimation method is applied to the whole available spectrum. The TOA estimation error Cramer-Rao bounds of both approaches are computed. The performances of the proposed algorithm are investigated via simulations. The complexities of the introduced techniques are compared. © 2013 IEEE

Near-Ground Channel Modeling for Distributed Cooperative Communications

© 2016 IEEE. A computationally efficient near-ground field prediction model is proposed to facilitate realistic wireless sensor network (WSN) simulations. In this model, using the principle of Fresnel zones, path loss is split into three segments. Certain propagation mechanisms dominate in each part. The distances that define the edges of each section are derived theoretically. The model is validated against several experimental datasets obtained in open and forested areas. It is noticed that the proposed model has higher accuracy compared to existing analytical near-ground propagation models. This enhancement is achieved by careful assessment of key features relevant to near-grazing propagation such as diffraction loss due to obstruction of the first Fresnel zone and higher order waves produced by terrain irregularities. Monte Carlo simulations are used to investigate the effects of antenna height, frequency of operation, polarization, and terrain dielectric and roughness properties on WSNs performance. It is realized that antenna height is by far the most influential geometric parameter to low-altitude WSNs connectivity and average number of neighbors

Handbook of Position Location: Theory, Practice, and Advances

Radio systems capable of localization have emerging applications in homeland security, law enforcement, emergency response, defense command and control, multi-robot coordination and vehicle-to-vehicle and vehicle-to-pedestrian collision avoidance. In fact, high resolution localization is vital for many applications, including: traffic alert, emergency services, e.g., indoor localization for firefighters, and battlefield command and control. These systems promise to dramatically reduce society\u27s vulnerabilities to catastrophic events and improve its quality of of life. While work this important area is progressing, limited resources are available to support graduate students and researchers in this important area. Specifically, a limited number of books has been published in this area covering selected subjects. This comprehensive handbook offers gaps of available localization books presenting in-depth coverage from fundamentals of coordinates to advanced application examples