卫星通信系统在人防应急通信中的应用研究

近些年,随着防空防灾系统的不断发展和完善,人防应急通信系统逐渐引起了国内外广大学者们的重视,它在各大领域中的地位也有了显著的提高。为了在各类人防应急事件时能更好的进行协调统一调度,对人身安全和公共或私有财产安全进行更好的保护,各国都相继建立了自己的人防应急系统。本文主要针对人防应急通信统中卫星通信的应用进行了较为全面的分析,并且针对人防应急通信中卫星通信系统的使用应注意的问题,进行了相应的阐述。

美海军UHF卫星通信系统研究

简要阐述美海军UHF卫星通信系统的发展演变历史,对美海军现役的UFO(特高频后继星)卫星通信系统的基本情况进行描述,在此基础上着重介绍美海军下一代窄带UHF卫星通信系统——MUOS(移动用户目标系统),包括其组成结构、主要性能参数、所能提供的业务等。

弹星通信链路建模仿真技术及窄带干扰抑制算法研究

论文弹星通信链路建模仿真技术及窄带干扰抑制算法研究,文章主要是分析了卫星导航系统的组成、DSSS技术,在此基础上通过研究弹 星返向通信链路系统建模仿真,研究了弹星通信系统窄带干扰抑制算法,望可以为有关人员提供到一定的参考和帮助。

编队飞行航天器的测量通信一体化系统——射频收发器

航天编队飞行必须测定队列的相对位置、姿态和时间，还必须有适当手段在航天器间交换工程数据和科学实验数据.研究和开发射频收发器对于我国发展航天编队飞行技术有特别的紧迫性和现实的意义.本文介绍并分析了国外在研的射频收发器研发情况，提出以实现星上测量、通信、制导、导航和控制一体化为最终目标，逐步、有层次、分阶段地开发射频收发器技术的系列思考和建议。

Coding Scheme for Ka-Band Fixed Satellite Communication System

The performance analysis and simulation of coding schemes based on the modeling Ka band fixed satellite channel have been presented. The results indicate that concatenated codes with large inner interleaving depth have good performance and high spectrum efficiency. The studies also show that simple block interleaving is very effective in combating the slow frequency nonselective fading of Ka band.

LTE-Satellite: Chinese Proposal for Satellite Component of IMT-Advanced System

As a complementary to terrestrial mobile communication systems, mobile satellite communication system can fill the gaps that cannot be covered by terrestrial network, and provides an irreplaceable solution for emergency communication in disaster. To pave the road for future satellite/terrestrial integrated communication networks, ITU-R invited proposals for candidate Radio Interface Technology(RIT) for the satellite component of International Mobile Telecommunications(IMT)-Advanced. China proposed the RIT of Long Term Evolution(LTE)-satellite as a candidate to be considered as IMT-Advanced satellite technology. The submitted LTE-satellite candidate RIT is specified based on terrestrial LTEAdvanced FDD standards that are developed in 3GPP. Considering satellite requirements, a number of modifications to LTE-Advanced are made to adapt to satellite radio transmission environments. This paper provides a general introduction of the new characteristics of LTEsatellite.

Capacity Maximization Based Power Loading Analysis for Digital Channelized Satcom Systems

For digital channelized frequency division multiple access based satellite communication(SATCOM) systems,it is a challenging but critical issue to improve the transponder power and spectrum efficiency simultaneously under limited and non-linear high-power amplifier conditions.In this paper,different from the traditional link supportability designs aiming at minimizing the total transponder output power,a maximal sum Shannon capacity optimization objective is firstly raised subject to link supportability constraints.Furthermore,an efficient multilevel optimization(MO) algorithm is proposed to solve the considered optimization problem in the case of single link for each terminal.Moreover,in the case of multiple links for one terminal,an improved MO algorithm involving Golden section and discrete gradient searching procedures is proposed to optimize power allocation over all links.Finally,several numerical results are provided to demonstrate the effectiveness of our proposals.Comparison results show that,by the MO algorithm,not only all links' supportability can be guaranteed but also a larger sum capacity can be achieved with lower complexity.

Timing Advanced Estimation Algorithm of Low Complexity Based on DFT Spectrum Analysis for Satellite System

In satellite mobile communication system, relative movement of the satellite and the terminal will cause a large Doppler offset. Timing advanced estimation with Zadoff-Chu sequence is sensitive to the frequency offset. When the frequency offset is larger than one times subcarrier spacing, the value of peak cannot be detected at the receiving end. To suppress the larger Doppler frequency shift, this paper proposes a novel timing advanced estimation scheme(TAE-MCD) for satellite communication system. In this algorithm, t r a n s m i t t e d s i g n a l i s d i v i d e d i n t o Z C sequence and its conjugate sequence. Using multiplication and DFT operation to find the estimated peak at the receiving end, and make subtraction with the obtained sequences at last. The scheme can not only inhibit the adverse effects of large Doppler frequency shift in timing estimation effectively, but also reduce the computational complexity at the receiving end and improve the work efficiency of the hardware. Simulations results show that TAEMCD outperform the existing timing advanced estimation methods, on the condition of no additional time and frequency resource are needed.

Non-Orthogonal Multi-Carrier Transmission for Internet via Satellite

As the important complementary to terrestrial mobile communications, Internet via satellite can extend the coverage of communication and improve the continuity of data services. To build a space-terrestrial integrated communication system is the inevitable trend in the future. Taking into account combination of 5th generation(5G) terrestrial mobile communication system and satellite communication system, it is necessary to evaluate the promising 5G air interface waveform which can be adopted by satellite. In this paper, several non-orthogonal multi-carrier transmission schemes are evaluated and generalized frequency division multiplexing(GFDM) is advised as potential scheme of space-terrestrial integrated communication system. After the overview of GFDM, the implementation of GFDM transceiver is discussed respectively in time-domain and in frequency-domain. By deriving and comparing implementation complexity, GFDM modulation in time-domain is more suitable for satellite communication system. Then the properties of demodulation algorithms are specified. Based on designed pilot subcarriers, a new improved receiving algorithm is proposed in the end of the paper. The improved algorithm solves the problem of inter subcarriers interference(ICI) in matched filtering(MF) receiver and improves the re-ceiving symbol error rate(SER) obviously. The simulation and analysis prove that the proposed algorithm is effective.

Frequency Offset Compensation for Satellite Communication System with CE-OFDM

Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, the carrier frequency offset(CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CEOFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise(AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio(SNR).

An L-strip fed stacked patch antenna for maritime satellite communications

A practical antenna has been designed and developed for INMARSAT mobile satellite communications. The design uses low cost materials such as foam and copper foil to create a stacked microstrip antenna array. Several techniques were adopted to enhance the impedance bandwidth and axial ratio bandwidth. The final design parameters were optimized by EM simulation. Finally, the L-strip fed six-element stacked microstrip antenna array was constructed and tested. Simulated and measured results show that in the whole INMARSAT work band, the VSWR of the antenna is less than 1.6, its antenna gain is higher than 15dB and wide-angle axial ratio （AR） 3dB is more than 21°. The antenna has been successfully used with a HNS 9201 terminal.

A high-level synthesis based dual-module redundancy with multi-residue detection(DMR-MRD)fault-tolerant method for on-board processing satellite communication systems

On board processing(OBP) satellite systems have obtained more and more attentions in recent years because of their high efficiency and performance.However,the OBP transponders are very sensitive to the high energy particles in the space radiation environments.Single event upset(SEU)is one of the major radiation effects,which influences the satellite reliability greatly.Triple modular redundancy(TMR) is a classic and efficient method to mask SEUs.However,TMR uses three identical modules and a comparison logic,the circuit size becomes unacceptable,especially in the resource limited environments such as OBP systems.Considering that,a new SEU-tolerant method based on residue code and high-level synthesis(HLS) is proposed,and the new method is applied to FIR filters,which are typical structures in the OBP systems.The simulation results show that,for an applicable HLS scheduling scheme,area reduction can be reduced by 48.26%compared to TMR,while fault missing rate is 0.15%.

Emerging trends in information and communication technology in mine safety and disaster management

There is tremendous growth in the use of Geographic Information Systems(GIS), Global Positioning Systems (GPS), Remote Sensing, Satellite Communication, andModeling & Simulation techniques.These tools and techniques helps significantly in characterizinginfrastructure, risk area and disaster zones, planning and implementation ofhazards reduction measures etc.Communication satellites becomes vital for providingemergency communication and timely relief measures.Integration of space technologyinputs into natural disaster monitoring and mitigation mechanisms is critical for hazard reduction.This paper mainly focused on all the issues described above.Major emphasis hadbeen given to the recent developments in information & communication technology enabledtools and their applications in mining industries for safe mining operations with increasedproductivity.

A Power Reduction Method for Pilot Channel of LEO Satellite Based on Dynamic Compensation

Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.

Efficient Single Event Upset-Tolerant FIR Filter Design Based on Residue Number for OBP Satellite Communication Systems

Cosmic radiation has several effects on the On-Board Processing(OBP)platform in satellite communications systems,and Single Event Upsets(SEUs)are one of its most important effects.In order to protect the Finite Impulse Response(FIR)filters against SEU,this paper proposes a novel Residue Number(RN)-based method.The proposed method applies the transpose form of the FIR filter to avoid the fault missing caused by SEU on shift registers.It also adjusts the input intelligently to avoid the fault missing caused by SEU on the filter coefficients.After all the fault missing events are avoided,the modulus can be minimised to achieve the minimum overhead.Theoretical analysis and simulation results show that the noise introduced by the input adjustment is negligible.Fault injection shows that the fault missing rate of the proposed method is zero.Finally,FPGA implementation shows that the overhead of the proposed method is approximately 75% of Triple Modular Redundancy,and is only 1%-2% higher than that of the traditional RN-based design.

China's First HTS Broadband Satellite Communications System Construction Initiated

China Aerospace Science and Technology Corporation（CASC）and the People’s Government of Shenzhen Municipality co-hosted a ceremony for the contract signing of the high-throughput broadband satellite project and for the establishment of a joint venture on July23,marking the formal start of the construction of China’s first high-throughput broadband satellite communication system.

跨国公司大反攻

外资主导下的在华产业布局已经完成,下一步就是静静等待行业的全面开放......

Principle demonstration of fine pointing control system for inter-satellite laser communication

Due to high data rates and reliability,inter-satellite laser communication has developed rapidly in these days.However,the stability of the laser beam pointing is still a key technique which needs to be solved;otherwise,the beam pointing jitter noise would reduce the communication quality or,even worse,would make the inter-satellite laser communication impossible.For this purpose,a bench-top of the fine beam pointing control system has been built and tested for inter-satellite laser communication.The pointing offset of more than 100rad is produced by the steering mirror.With beam pointing control system turned on,the offset could be rapidly suppressed to lower than 100 nrad in less than 0.5 s.Moreover,the pointing stability can be kept at 40 nrad for yaw motion and 62 nrad for pitch motion,when the received beam jitter is set at 20rad.