The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We propose a Multi-Channel Pure Collective Aloha (MC-PCA) MAC protocol for asynchronous satellite uplink random access in this paper. The MC-PCA MAC protocol collects a batch of packets before selecting a channel randomly out of a number of channels and transmits these packets sequentially in the selected channel at one go. The key idea in the design of this proposed MC-PCA MAC protocol is to spread...
The urgency of reliable navigation for manned and self-driving vehicles in urban environment is growing. The de facto standard of mass-produced navigation systems is global navigation satellite system (GNSS). Standalone work of a GNSS receiver is possible while receiving at least 4 signals from different navigation satellites. Operating of GNSS receiver in an "urban canyon" is broken due...
In this paper, we propose a new positioning method by using wireless local area network systems based on a principle of the Real Time Kinematic-Global Positioning Systems (RTK-GPS). The proposed method collects observations of the carrier phase at access points for double phase difference of the RTK-GPS by following the point coordination function of the IEEE 802.11 standard. We show some numerical...
During the last few years, there has been a rise in the use of nanosatellites because they offer a low cost and short development time alternative to larger satellites intended for long-duration missions. The use of commercial components (COTS) instead of the expensive space-grade components required for long missions is one of the main reasons of the popularity of the nanosatellites. This paper presents...
Global navigation satellite system (GNSS) receivers are vulnerable to hostile interference threads, such as jamming and spoofing. A two-stage hybrid interference suppression scheme is proposed to enable mitigating jamming and spoofing ahead of acquisition, separately or simultaneously. An orthogonal complement space of spoofing signals is constructed at the first stage to cancel potential spoofers...
In recent years, GPS has been widely used as a positioning system using satellites. However, GPS receivers cannot position calculation their own positions when they can watch less than three Satellites directly. Therefore, in an environment where there are many obstacles such as urban area, there is a problem that it may be not possible to receive four or more GPS signals from GPS satellites. In this...
Single-carrier frequency-domain equalization (SC-FDE) occupies a concise transmitting structure and a low peak-to-average power ratio (PAPR). These advantages are conducive to the miniaturization of the satellite systems and increase the robustness to the non-linear distortion of amplifiers. Nowadays, satellite communication systems set out to work at Ka or higher frequency bands to support the high...
Detection and repair of cycle slips is the prerequisite for high precision positioning. This paper proposes a method uses modified MW combination and ionospheric combination. The multipath of MW combination is filtered and then the ionospheric combination is used. This method is able to detect small cycle slips and various combinations of cycle slips. This paper takes experiment on three kinds of...
Recently, utilization of position information by global navigation satellite system (GNSS) is expected in various fields. However, it's difficult to show unambiguously accuracy since positioning accuracy varies by measurement environment. We bring sky view factor (SVF) to evaluation of positioning accuracy, and evaluate it positioning accuracy of long time data in the places where SVF are high or...
Satellite selection is an important technology in Global Navigation Satellite Systems (GNSS), for which the dilution of precision (DOP) serves as the key performance metric. Selecting a satellites set with lower DOP often results more accurate positioning and timing. In this paper, the characteristics of DOP for dual-GNSS constellations is studied, where an uncertain clock offset is assumed between...
In this paper the power requirements of deception jamming in the signal acquisition phase of BeiDou navigation receiver are discussed in two cases. In the first case, the deception jamming signal is released before the start of the receiver, with the method of analyzing the signal acquisition probability model and the acquisition correlation peak, the conclusion is obtained that the effective power...
Accurate and reliable positioning of vehicles is a decisive factor for many Intelligent Transportation System (ITS) applications. Under the cooperative environment, the eco-driving at specific scenarios, like intersections, requires vehicle motion state information, which can be provided by Global Navigation Satellite System (GNSS) with an integrity monitoring capability. In order to provide effective...
In order to realize the rapid satellite selection of BDS / GPS dual-mode navigation system under the premise of satisfying the normal positioning accuracy, a new fast satellite selection algorithm is proposed. The algorithm combines the traditional satellite selection algorithm with genetic algorithm. The satellite area is divided by the elevation angles information of the visible satellite, according...
Combining the current development of high-gain antenna technology, the inter-satellite terahertz communication system's demand for acquisition pointing and tracking (Acquisition Pointing Tracking, APT) technology are analyzed based on the inter-satellite terahertz communication application. The tracking-pointing error has a major influence on the received power of the communication system by simulating...
In the integrated navigation system, the carrier phase has higher accuracy than the pseudo-range, but it has the problem of the solution of integer ambiguity. This paper proposes a GPS/INS integrated navigation algorithm based on the double-difference of time/inter-satellite with carrier phase. First, the algorithm is used to eliminate the influence of ambiguity by the simplified time-differenced...
In order to promote the popularization of BDS, the BDS / GPS dual-mode positioning is studied, and the pseudorange single point positioning algorithm of the dual-mode system is analyzed. On the basis of the least squares method, the weighted method is used to improve the accuracy of the positioning solution, and a fixed weight method combining the elevation angle model and posterior variance estimation...
In this paper results of research on RTK (Real Time Kinematic) technique used to develop small and lightweight receiver of GNSS (Global Navigation Satellite System) signals is presented. Experiments with such receivers show that they are able to deliver good quality position estimation of micro aerial vehicles in 3D space during a flight. The standard deviation of the position measurement is less...
The paper explores the shadows created by moving humans in two types of Forward Scatter (FS) systems, which use GPS signals and sound signals. The comparative analysis of results is based on the correlation analysis and focused on establishing of relationships between different types of shadows. The results show whether it is possible to use sound barriers for detection of moving objects.
A range of issues apply to getting time from GNSS receivers, depending strongly on what the user needs. The words "accurate time" mean very different things to different users. Accurate time from GNSS receivers becomes challenging as the required accuracy is better than a microsecond or so. While this paper discusses a broad range of issues related to accurate timing from GNSS, it focusses...
In Global Navigation Satellite Systems (GNSS), ionospheric scintillation is one of the more challenging propagation scenarios, particularly affecting high-precision receivers based on carrier phase measurements. In this contribution, we propose a new digital carrier synchronization state-space formulation for the mitigation of strong scintillation. It takes into account multi-frequency GNSS observations,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.