Propagation Delay Difference Estimation for Initial Random Access in LTE Compatible Mobile Satellite Communications System

2013 ◽  
Vol 846-847 ◽  
pp. 647-650
Author(s):  
Cheng Mei Li ◽  
Jian Jun Wu ◽  
Xiao Ning Zhang ◽  
Xi Luan ◽  
Hai Ge Xing
Keyword(s):  
Estimation Method ◽  
Random Access ◽  
Satellite Communications ◽  
Propagation Delay ◽  
Satellite System ◽  
Satellite Systems ◽  
Access Channel ◽  
Geo Satellite ◽  
Mobile Satellite ◽  
Delay Difference

In this paper, a two-step propagation delay difference estimation method is proposed for LTE compatible multi-beam satellite systems to ensure the initial random access (RA). For GEO satellite system, there exists a large propagation delay difference, we cannot directly apply the LTE delay estimation method. To deal with this issue, we first divide a satellite beam into some layered small sub-areas according to the different delay difference values. Then, two types of Physical Random Access Channel (PRACH) preamble burst format are given. The detailed PRACH parameters are provided. Finally, simulations are performed and the results verify the availability of our proposed design.

Access Control Algorithm with Limited Power Constraint for Mobile Satellite Communications

2014 ◽  
Vol 548-549 ◽  
pp. 1286-1289
Author(s):  
Ya Zhe Gao ◽  
Xiao Han Xia ◽  
Zi Ming Su ◽  
Xi Luan ◽  
Jian Jun Wu
Keyword(s):  
Admission Control ◽  
Control Algorithm ◽  
Load Capacity ◽  
Satellite Communications ◽  
Satellite System ◽  
Power Constraint ◽  
Priority Service ◽  
Limited Power ◽  
Mobile Satellite ◽  
Service Priority

The problem of admission control caused by the limitation of resource in hotspot beams in satellite system is considered in this paper. Based on the idea of borrowing resources from surrounding beams, we give a scheme that the beam reserve resources is borrowed proportionally. After that, the original admission control algorithm based on service priority is modified in order to protect access rate of the low priority service. Simulation results prove that the proved scheme can increases the available beam load capacity effectively and provide a guarantee for the access of those services with low priority.

Propagation Delay Characteristics Analysis in LEO Satellite Multi-Beam Antenna Coverage

2013 ◽  
Vol 791-793 ◽  
pp. 1931-1935
Author(s):  
Ming Ma ◽  
Xi Luan ◽  
Bin Li ◽  
Jian Jun Wu
Keyword(s):  
Satellite Communications ◽  
Propagation Delay ◽  
Satellite System ◽  
Calculation Model ◽  
Propagation Delays ◽  
Characteristics Analysis ◽  
Leo Satellite ◽  
Communications System ◽  
Calculated Analysis

In this paper a calculation model of propagation delays of satellite beams is introduced for LEO multi-beam satellite communications system. Based on actual parameters and beam coverage patterns of the Iridium and Globalstar system, the maximum propagation delay differentials in several typical beams from the center to the edge of the satellites coverage are calculated. Analysis of these results can provide reference for analyzing the feasibility of LEO multi-beam satellite system compatible with uplink synchronization in LTE.

A Precise Weighting Approach with Application to Combined L1/B1 GPS/BeiDou Positioning

2014 ◽  
Vol 67 (5) ◽  
pp. 911-925 ◽  
Author(s):  
Changsheng Cai ◽  
Lin Pan ◽  
Yang Gao
Keyword(s):  
Time Window ◽  
A Priori ◽  
Estimation Method ◽  
Satellite System ◽  
Positioning Accuracy ◽  
Satellite Systems ◽  
Beidou System ◽  
Component Estimation ◽  
Navigation Service ◽  
Global Navigation Satellite

The BeiDou system has been providing a regional navigation service since 27 December 2012. The Global Navigation Satellite System (GNSS) user community will benefit from combined Global Positioning System (GPS)/BeiDou positioning due to improved positioning accuracy, reliability and availability. But to achieve the best positioning solutions, precise weights of the GPS and BeiDou observations are important since this involves the processing of measurements from two different satellite systems with different quality. Currently, a priori variances are typically used to determine the weights of different types of observations. However, such an approach may not be precise since many un-modelled errors are not accounted for. The Helmert variance component estimation method is more appropriate in this case to determine the weights of GPS and BeiDou observations. This requires high redundant observations in order to obtain reliable solutions, which will be a concern in the case of insufficient numbers of visible satellites. To address this issue, a weighting approach is proposed by a combination of the Helmert method and a moving-window average filter. In this approach, the filter is applied to combine all epoch-by-epoch weight estimates within a time window. As a result, more precise and reliable weights for GPS and BeiDou observations can be obtained at every epoch. Both static and kinematic tests in open sky and under tree environments are conducted to assess the performance of the new weighting approach. The results indicate significantly improved positioning accuracy.

scholarly journals A Novel Approach to Wideband Spectrum Compressive Sensing Based on DST for Frequency Availability in LEO Mobile Satellite Systems

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Feilong Li ◽  
Guangxia Li ◽  
Zhiqiang Li ◽  
Yulin Wang ◽  
Gengxin Zhang
Keyword(s):  
Compressed Sensing ◽  
Signal Detection ◽  
Sampling Rate ◽  
Satellite System ◽  
Spatial Diversity ◽  
Decision Fusion ◽  
Processing Load ◽  
Satellite Systems ◽  
Novel Approach ◽  
Mobile Satellite

In LEO mobile satellite network, the L/S frequency availability is an essential task for global communication but entails several major technical challenges: high sampling rate required for wideband sensing, limited power and computing resources for processing load, and frequency-selective wireless fading. This paper investigates the issue of frequency availability in LEO mobile satellite system, and a novel wideband spectrum compressed signal detection approach is proposed to obtain active primary users (PUs) subbands and their locations that should be avoided during frequency allocation. We define the novel wideband spectrum compressed sensing method based on discrete sine transform (DST-WSCS), which significantly improves the performance of spectrum detection and recovery accuracy compared with conventional discrete Fourier transform based wideband spectrum compressed sensing scheme (DFT-WSCS). Additionally, with the help of intersatellite links (ISL), the scheme of multiple satellites cooperative sensing according to OR and MAJ decision fusion rules is presented to achieve spatial diversity against wireless fading. Finally, in-depth numerical simulations are performed to demonstrate the performance of the proposed scheme in aspect of signal detection probability, reconstruction precision, processing time, and so forth.

Obstacles to the Establishment of Mobile Satellite Communications

1973 ◽  
Vol 26 (2) ◽  
pp. 145-151
Author(s):  
D. O. Fraser
Keyword(s):  
Western Europe ◽  
Satellite Communication ◽  
Satellite Communications ◽  
Space Technology ◽  
Satellite Systems ◽  
Work Sharing ◽  
Commercial Space ◽  
Electrical Engineers ◽  
Mobile Satellite ◽  
Mobile Satellite Communication

The present deadlock between Western Europe and U.S.A. reflects a difference in emphasis on motivation largely traceable to the space technology gap. The problem is to establish institutional and work sharing arrangements bridging U.S. desire for early commercial space exploitation and European desire to promote its industrial space techology. The European approach is compatible with I.C.A.O. and I.A.T.A. preference for a non-operational experimental first phase Aerosat programme, and unless a compromise with U.S.A. is reached the best solution may be a European E.S.R.O. programme able to cater for the experimental mobile satellite communication system requirements of both aviation and shipping. The paper was presented at the Conference on Aeronautical and Maritime Satellite Systems held in London on 13–15 March and sponsored jointly by the Institution of Electrical Engineers with this Institute, the Institution of Electronic and Radio Engineers and the European Space Research Organization.

scholarly journals Evaluation The Performance Geodetic of the Receivers Using Static Positioning Technique

2018 ◽  
Vol 24 (10) ◽  
pp. 98
Author(s):  
Omar Ali Ibrahim
Keyword(s):  
Satellite Communications ◽  
Satellite System ◽  
Web Based ◽  
Static Mode ◽  
Total Station ◽  
Land Surveying ◽  
Gnss Receivers ◽  
Positioning Technique ◽  
Mobile Satellite ◽  
Global Navigation Satellite

Global Navigation Satellite System (GNSS) is considered to be one of the most crucial tools for different applications, i.e. transportation, geographic information systems, mobile satellite communications, and others. Without a doubt, the GNSS has been widely employed for different scientific applications, such as land surveying, mapping, and precise monitoring for huge structures, etc. Thus, an intense competitive has appeared between companies which produce geodetic GNSS hardware devices to meet all the requirements of GNSS communities. This study aims to assess the performance of different GNSS receivers to provide reliable positions. In this study, three different receivers, which are produced by different manufacturers, were fixed to form a triangle. Simultaneous observations were made in static mode (2.5 to 3 hours). This observation technique was carried out three times by changing the location of receivers in each time to ensure that three receivers observed each station three times. To evaluate the performance of each receiver, OPUS web-based processing software and TOPCON TOOLS were used to process the raw GNSS observations. The distances between adjacent stations were computed for each observation and compared to standard distances, which were measured using a total station. Furthermore, the internal angles were also computed and compared to those measured by Total Stations. The results showed that some calculated distances are closer to the corresponding distances measured by the total station. This indicates that the receivers involved in the composition of these distances are the most accurate.  

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