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The paper analyzes various approaches that can improve accuracy of time scales comparison by GLONASS signals. The results of their testing with using new dual-frequency Time Transfer Unit developed at Russian Institute of Radionavigation and Time (RIRT) are presented.
At present, many Beidou tracking stations over the world have been set up for international GNSS Monitoring and Assessment System (iGMAS) and a pilot project named Multi-GNSS Experiment (MGEX) is implemented. Each station was equipped with the Multi-GNSS receivers which are able to track BeiDou as well as GPS signals. Furthermore some of stations were equipped with high-precision atomic clocks as...
Existing techniques for measuring available bandwidth measure the available bandwidth at bottlenecks along the path, and most of them do not specify the bottleneck location. In this paper, we propose an end-to-end measurement method for the hop-by-hop available bandwidth along a network path. Such a technique can facilitate advanced traffic control, especially in heterogeneous network environments...
Safe navigation in non-familiar outdoor environments is a challenging activity for the blind and visually impaired (BVI) people. This work introduces a cloud-based outdoor assistive navigation system (COANS) for BVI people. The main goal of the system is to provide easy street navigation and help to make outdoor walk in non-familiar environment less stressful. Hardware part from the user-side includes...
This paper presents multi GNSS Advanced Receiver Autonomous Integrity Monitoring (ARAIM) availability for vertical guidance of aircraft down to LPV-200. Our analysis is based on two data sets: real and simulated data. For analysis based on simulated data, we use MATLAB Algorithm Availability Simulation Tool (MAAST) for availability analysis. Analysis based on real data is carried out using pseudorange...
This paper proposes a local augmentation and integrity monitoring network for railway and shows the obtained performances in terms of accuracy positioning in case of satellite faults. The simulations results show that the system can detect and discard tha faulty satellite, still mantaining the accuracy on positioning accetable. The work is inserted in the scenario of introduction and application of...
Time-based localization techniques such as multilateration are favoured for positioning to wide-band signals. Applying the same techniques with narrow-band signals such as GSM is not so trivial. The process is challenged by the needs of synchronization accuracy and timestamp resolution both in the nanoseconds range. We propose approaches to deal with both challenges. On the one hand, we introduce...
A method for tightly-coupling carrier-phase differential GPS with ultra-wideband (UWB) ranging for vehicle-to-infrastructure relative navigation is proposed. Relative position, velocity, clock errors, GPS phase ambiguities and UWB systematic errors are estimated using an extended Kalman filter. The method is tested with real data and evaluated in terms of position accuracy, GPS float ambiguity convergence,...
Three major obstacles to wireless communication are electromagnetic interference, multipath fading and signal attenuation. The former stems mainly from collocated wireless systems operating in the same frequency band, while the latter two originate from physical properties of the environment. Identifying the source of packet corruption and loss is crucial, since the adequate countermeasures for different...
Recently, carrying control signals on passing data packets has emerged as a promising direction for efficient control information transmission. With control messages carried on data payload, the extra air time needed for control packets like RTS/CTS is eliminated and thus channel utilization is improved. However, carrying control signals on the data payload of a packet requires the data packet to...
This paper focuses on radio frequency identification (RFID) based 3D real-time locating systems aiming to compare different approaches utilizing passive or active transponders with or without reference nodes. An active approach given by Chong Wang et al. is compared against an passive approach given by Chong Wang et al. and the STAR system from the company Mojix. The details of the three compared...
Counting and identifying neighboring active nodes are two fundamental operations in wireless sensor networks (WSNs). In this paper, we propose two mechanisms, Power based Counting (Poc) and Power based Identification (Poid), which achieve fast and accurate counting and identification by allowing neighbors to respond simultaneously to a poller. A key observation that motivates our design is that the...
Automatic Dependent Surveillance-Broadcast (ADS-B) is one of the key components of the next generation air transportation system. Since ADS-B will become mandatory by 2020 for most airspaces, it is important that aspects such as capacity, applications, and security are investigated by an independent research community. However, large-scale real-world data was previously only accessible to a few closed...
High accuracy equalization and high power supply rejection ratio equalizer in the receiver of a high-speed serial link presented. To validate the proposed architecture, conducted experiments, for examples, with various injected faults, for which the conventional approach of examining the eye opening at the output of the equalizer results. Proposed equalizer have supply noise with 35% higher rejection...
This paper describes a 10-bit 25MSPS analog-to-digital converter (ADC) for Mobile HDTV Receiver System. The ADC is based on a 4-3-3 bits- per-stage pipeline architecture and The proposed pipelined ADC adopts a optimized stage resolution based on power consumption of sample and hold circuit and comparator. At the target sampling rate of 25MS/s, measured results show that the converter consumes 12.36mW...
In this paper a comparison of analog versus digital information is given, where the superior noise resilience of digital signals is shown to necessitate digital signalling for modern high-speed signaling environments. Non-idealities that are analog in nature are shown to necessitate ADCs in the digital signal path, which allow for signal recovery in the digital domain. A brief discussion of the Flash...
Localization is extensively used in Wireless Sensor Networks (WSNs) to identify the current location of the sensor nodes. A WSN consist of thousands of nodes that make the installation of GPS on each sensor node expensive and moreover GPS will not provide exact localization results in an indoor environment. Manually configuring location reference on each sensor node is also not possible in the case...
Equivalent time sampling causes noise in reconstructed pulse stream due to the transmitter or receiver jitter or path variations. When this pulse stream is used for localization, system accuracy is limited by the reconstructed pulse signal to noise ratio (SNR). In this paper, the jitter effects from transmitter and receiver on reconstructed pulse are simulated and an improvement technique based on...
The time difference of arrival (TDOA) positioning method is a classic method that is used to determine the unknown location of a transmitting wireless terminal, based on the time differences in the signals that are received at different receivers. In this research the method is studied for two- dimensional (2-D) problems for simplicity, for an electromagnetic dipole source radiating a carrier wave...
The expansion of Wireless Local Area Networks (WLAN) especially the advances in localization based technologies has generated a growing interest in an indoor Wireless Positioning Systems (WPS) based on WLAN infrastructure. This paper presents the preliminary study on two indoor positioning techniques, known as fingerprinting and clustering technique by leveraging the existing Wireless Local Area Network...
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