543 research outputs found
Analysis of Ultra Wide Band (UWB) Technology for an Indoor Geolocation and Physiological Monitoring System
The goal of this research is to analyze the utility of UWB for indoor geolocation and to evaluate a prototype system, which will send information detailing a person’s position and physiological status to a command center. In a real world environment, geolocation and physiological status information needs to be sent to a command and control center that may be located several miles away from the operational environment. This research analyzes and characterizes the UWB signal in the various operational environments associated with indoor geolocation. Additionally, typical usage scenarios for the interaction between UWB and other devices are also tested and evaluated
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A Markov Model for Dynamic Behavior of Toa-Based Ranging in Indoor Localization
The existence of undetected direct path ( UDP) conditions causes occurrence of unexpected large random ranging errors which pose a serious challenge to precise indoor localization using time of arrival ( ToA). Therefore, analysis of the behavior of the ranging error is essential for the design of precise ToA-based indoor localization systems. In this paper, we propose a novel analytical framework for the analysis of the dynamic spatial variations of ranging error observed by a mobile user based on an application of Markov chain. the model relegates the behavior of ranging error into four main categories associated with four states of the Markov process. the parameters of distributions of ranging error in each Markov state are extracted from empirical data collected from a measurement calibrated ray tracing ( RT) algorithm simulating a typical office environment. the analytical derivation of parameters of the Markov model employs the existing path loss models for the first detected path and total multipath received power in the same office environment. Results of simulated errors from the Markov model and actual errors from empirical data show close agreement
Ultra Wideband Indoor Navigation System
Typical indoor environments contain multiple walls and obstacles consisting of different materials. As a result, current narrowband radio frequency (RF) indoor navigation systems cannot satisfy the challenging demands for most indoor applications. The RF ultra wideband (UWB) system is a promising technology for indoor localisation owing to its high bandwidth that permits mitigation of the multipath identification problem. This work proposes a novel UWB navigation system that permits accurate mobile robot (MR) navigation in indoor environments. The navigation system is composed of two sub-systems: the localisation system and the MR control system. The main contributions of this work are focused on estimation algorithm for localisation, digital implementation of transmitter and receiver and integration of both sub-systems that enable autonomous robot navigation. For sub-systems performance evaluation, statics and dynamics experiments were carried out which demonstrated that the proposed system reached an accuracy that outperforms traditional sensors technologies used in robot navigation, such as odometer and sonar.Fil: Segura M.. Universidad Nacional de San Juan; ArgentinaFil: Mut, Vicente Antonio. Universidad Nacional de San Juan; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Sisterna C.. Universidad Nacional de San Juan; Argentin
Channel Sounding for the Masses: Low Complexity GNU 802.11b Channel Impulse Response Estimation
New techniques in cross-layer wireless networks are building demand for
ubiquitous channel sounding, that is, the capability to measure channel impulse
response (CIR) with any standard wireless network and node. Towards that goal,
we present a software-defined IEEE 802.11b receiver and CIR estimation system
with little additional computational complexity compared to 802.11b reception
alone. The system implementation, using the universal software radio peripheral
(USRP) and GNU Radio, is described and compared to previous work. By overcoming
computational limitations and performing direct-sequence spread-spectrum
(DS-SS) matched filtering on the USRP, we enable high-quality yet inexpensive
CIR estimation. We validate the channel sounder and present a drive test
campaign which measures hundreds of channels between WiFi access points and an
in-vehicle receiver in urban and suburban areas
ANALYSIS AND ESTIMATION OF TIME OF ARRIVAL AND RECEIVED SIGNAL STRENGTH IN WIRELESS COMMUNICATION FOR INDOOR GEOLOCATION
Analysis and estimation of the time of arrival and received signal strength for indoor geolocation using MATLAB describes an indoor geolocation localization which either use the received signal strength (RSS) or time of arrival (TOA) of the received signal as their localization metric. Though time of arrival based systems are sensitive to the available bandwidth and also to the occurrence of undetected direct path (UDP) channel conditions which RSS based system are less sensitive to the bandwidth as more resilient to undetected conditions. This paper demonstrate the availability of radio channel modeling techniques to eliminate the costly finger printing process in pattern recognition algorithms by introducing ray tracing (RT) assisted by RSS and TOA based algorithms. The results in figure 8 which shows the effect of pathloss on signal reception, showing free path loss reduces when plotted with rhe height of the building which can be used for achieving localization. it was also disovered that path loss also contributes to signal delay, the plot in figure 12 which is a probability distribution of received signal strength at different location which detect signal at the point where maximum signal was received , this RSS at fixed positions can be used to determine geolocation
Effects of Multipath and Oversampling on Navigation Using Orthogonal Frequency Division Multiplexed Signals of Opportunity
The Global Positioning System (GPS) has become the primary system for navigation and precise positioning. GPS has limitations, though, and is not suitable in environments where a line-of-site (LOS) path to multiple satellites is not available. Reliable alternatives need to be developed to provide GPS-like positioning when GPS is unavailable. One such alternative is to use signals of opportunity (SoOP). This concept refers to navigation using signals which inherently exist in the environment and were developed for non-navigation applications. This research focuses on exploiting the Orthogonal Frequency Division Multiplexed (OFDM) signal for the purpose of navigation. An algorithm was developed to simulate a transmitter, receiver, channel noise, and multipath propagation. A transmitter and reference receiver, both at known locations, and a mobile receiver at an unknown location were used to conduct simulations with a transmitted OFDM signal in a Rayleigh-distributed multipath environment. The OFDM signal structure was exploited by using its cyclic prefix in a correlation process to find the first symbol boundary in each received signal. Each receiver calculates statistical features about each symbol in the received signal. These two sets of data are then correlated in order find the difference in symbol arrival times. The simulations were run for varying levels of oversampling in an effort to gain more accurate results by decreasing the sample period. Results show that oversampling the signal only slightly reduces errors in the symbol boundary correlation process, while multipath has a significant impact on correlation performance. It was also found that increasing the window size significantly improved feature correlator performance and yielded promising results even in the presence of high multipath environments
An Overview of Massive MIMO Research at the University of Bristol
Massive MIMO has rapidly gained popularity as a technology crucial to the
capacity advances required for 5G wireless systems. Since its theoretical
conception six years ago, research activity has grown exponentially, and there
is now a developing industrial interest to commercialise the technology. For
this to happen effectively, we believe it is crucial that further pragmatic
research is conducted with a view to establish how reality differs from
theoretical ideals. This paper presents an overview of the massive MIMO
research activities occurring within the Communication Systems & Networks Group
at the University of Bristol centred around our 128-antenna real-time testbed,
which has been developed through the BIO programmable city initiative in
collaboration with NI and Lund University. Through recent preliminary trials,
we achieved a world first spectral efficiency of 79.4 bits/s/Hz, and
subsequently demonstrated that this could be increased to 145.6 bits/s/Hz. We
provide a summary of this work here along with some of our ongoing research
directions such as large-scale array wave-front analysis, optimised power
control and localisation techniques.Comment: Presented at the IET Radio Propagation and Technologies for 5G
Conference (2016). 5 page
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