BPSK and QPSK non‐linear satellite communication system performance in the presence of cochannel interference

Taking the uplink and downlink cochannel interference and noise into account, the analytical expressions are derived for determining the bit error probability in detecting a binary phase‐shift‐keying (BPSK) and a quaternary phase‐shift‐keying (QPSK) Gray coded signal, transmitted over a satellite system exhibiting amplitude modulation‐to‐amplitude modulation (AM/AM) conversion effects and amplitude modulation‐to‐phase modulation (AM/PM) conversion effects. On the basis on the derived theoretic formulae, using real‐life system parameters, numerical results are obtained and presented. We point out the explicit comparisons of satellite communication system performance obtained when a satellite transponder amplifier is modelled by a hard‐limiter and those obtained when both AM/AM and AM/PM non‐linearities of the satellite transponder amplifier are taken into consideration. Copyright © 2003 John Wiley & Sons, Ltd.     

阴影对GMSK卫星移动通信系统性能的影响

导出了采用L重最大比组合（MRC）和差分相位检测（DPD）方案的高斯最小频移键控（GMSK）卫星移动通信系统在不同信道条件下的误比特率公式，并利用实测数据给出数值计算结果。可用于分析阴影特性对卫星移动信道性能的影响并指导系统设计。     

一种用于高速QPSK解调的四次方环载波恢复电路

为解决高速QPSK信号全数字解调的技术瓶颈问题,采用模拟方案,研制了一种四次方环载波恢复电路,重点介绍了应用混频器上变频特性的宽带平方电路以及锁相环(PLL)载波提取电路的设计过程.测试结果表明,该载波恢复电路可以完成载频为720 MHz、码速率100 Mbit/s～1 Gbit/s范围的QPSK信号同步载波恢复,解决了高速信号相干解调中载波同步的关键技术问题.     

毫米波通信系统QPSK调制器设计

为解决毫米波通信系统中数据速率和频谱资源紧张的难题,采用直接数字频率合成(DDS)和锁相环(PLL)技术,基于改进的π/4-QPSK调制方式,以现场可编程门阵列（FPGA）为控制单元,设计了一种用于毫米波通信系统的QPSK调制器。重点介绍了应用FPGA实现Gold码的编码过程,并给出了Gold编码Modelsim仿真结果。测试结果表明,该毫米波调制器工作稳定,QPSK调制信号中心频率30 GHz,数据速率3 Gb/s,输出功率大于4 dBm,相位噪声优于-100 dBc/Hz@10 kHz,可用于实际工程。     

卫星通信与5G融合系统发展探究

5G具有先进和成熟的技术,而卫星通信具有天然优势,例如灵活提供网络无线宽带回传、大广域广播多播、安全应急类通信等,是未来移动通信的重要组成部分.文章分析了5G和卫星通信发展情况,以及融合场景与核心技术,表达了对未来发展的展望,为相关人员提供参考.     

卫星相干光通信跟瞄误差对链路性能的影响

以星间相干激光通信链路的接收机相干效率为研究对象,分析了动态跟瞄误差对相干效率的影响,将相干效率引入到星间相干激光通信链路方程,推导了跟瞄误差波前失配条件下的相干光通信链路的误码率概率表达式,对卫星激光通信链路中跟瞄对准误差导致的相干效率下降、链路误码性能劣化情况进行了仿真计算。结果表明,由于跟瞄对准误差波前失配的影响,相干激光通信接收终端具有一个优化的接收孔径,在本仿真条件下,LEO-GEO星间链路动态跟瞄误差为0.5μrad时,优化接收孔径为0.5 m,链路可获得最佳误码性能。     

一种低截获卫星通信技术及其抗侦测性能分析

针对海上低截获通信应用,提出了一种低截获卫星通信技术并分析了其抗侦测性能。通过宽频带、低信息速率实现高增益扩频,系统设计上综合高工作频率、高增益天线等措施,降低卫星通信信号的功率谱密度;结合卫星链路计算,重点分析在同步轨道、低轨道电子侦察卫星侦测时的抗截获性能。理论分析和数值计算结果表明,增大扩频增益和天线增益可有效对抗同步轨道电子侦察卫星天线增益优势,对抗低轨道电子侦察卫星轨道优势,实现卫星低截获通信。     

Standardization on performance objectives of satellite systems using adaptive coding and modulation

The radiocommunication part of the International Telecommunication Union (ITU‐R) establishes the standards for wireless communications. Recommendation ITU‐R S.1062 specifies the performance objectives for satellite communication systems providing constant bit rate service. However, this is not applicable to most modern satellite communication systems utilizing adaptive coding and modulation (ACM) schemes to compensate for channel impairments, especially for systems operating in high frequency bands. For this reason, ITU‐R recently developed Recommendation ITU‐R S.2131 that is suitable for satellite systems with ACM. The developed Recommendation provides a method to determine performance objectives for satellite systems using ACM. Two possible objective parameters are presented, including packet error rate and spectral efficiency. This paper presents the standardization process, and the background used to establish new performance objectives. In addition, interpretations of the objectives are given by using estimation results for two different propagation characteristics.     

The simulation modelling and performance analysis of low earth orbit satellite communication networks for personal communications

This paper extends previous research efforts related to the simulation performance modelling and analysis of satellite communication networks. Specifically, the use of low earth orbit (LEO) satellite networks for personal communications is examined. Six different satellite constellation configurations are investigated in a packet‐switched operating environment. Performance metrics examined are the end‐to‐end packet delay and the utilization of satellite channels in the dynamic environment. Realistic and accurate models of the physical satellite network and its terrestrial transmitters require that numerous operating characteristics and assumptions be specified. These are based on proposed design requirements of commercial systems, such as Iridium. Via the use of simulation, we show the relative delay and utilization performance of differing satellite network architectures. From these simulation models, mathematical metamodels are derived for the system delays. These innovative models are used to predict the delay performance of different network architectures not previously simulated. Comparison of these metamodels with simulation results show that metamodels provide an accurate means for performance prediction. Copyright © 1999 John Wiley & Sons, Ltd.     

基于卫星和集群通信的渔船组网技术与应用

渔业公司船多且作业队伍不固定,通过在每艘船上加装卫星通信终端来解决远洋宽带通信问题成本很高。根据船队分为指挥船与任务船两类,出海作业时每组由一艘指挥船带领若干任务船的特点,在指挥中心和指挥船之间建立卫星通信网络,在指挥船和任务船之间建立移动宽带多媒体通信网络,并辅以组播、路由自动切换等策略。建成后的系统可实现任意船只之间以及船与指挥中心间的宽带互联互通,指挥船与任务船随机组队时,链路可自适应,系统无需重新配置,指挥船与任务船间宽带通信距离大于20 km。该系统可大大降低渔业公司远洋宽带通信网络的建设成本与运营成本。     

卫星移动通信信道LR2模型及系统性能分析

在对卫星移动通信信道传播特性进行分析的基础上,综合目前提出的各种卫星移动信道传播模型,提出了一种新的Lognormal—Rice—Rayleigh模型(简称LR^2模型)。从该模型可以推导到其它各种经典的卫星移动信道传播模型,并且具有良好的全波段特性(从UHF到Ka)和实际逼真度。还给出了LR^2模型从UHF到Ka各个波段的仿真效果和参数优化公式,全面分析了与信道模型有关的各种参数如电平通过率(LCR)、平均衰落时长(AFD)、相位分布、误码率、块差错率等,为信道模型的应用作了较全面的阐述。     

Performance of the combining received differential encoding transmit diversity with imperfect carrier recovery over correlated Nakagami fading channels

A differential detection scheme for transmit diversity was proposed by Tarokh, which can achieve full diversity order without the requirement to estimate the channel state at the receiver. This paper investigates the potential of using multiple receive antennas for differential space time coded MPSK signals over correlated Nakagami fading channels. We also investigate the effect of the carrier frequency offset (CFO) and channel correlation on its performance and present some results on its maximal tolerable frequency offsets for different MPSK signals. The results have shown that the differential encoding transmit diversity is very robust to the CFO and channel correlation. Copyright © 2004 John Wiley & Sons, Ltd.     

Estimation of the error performance objectives for satellite communication systems

We consider the physical layer error performance parameters and design criteria for digital satellite systems established by ITU‐R Recommendation S.1062, where the performance objectives are given in terms of the bit error rate (BER) divided by the average number of errors within a cluster. It is well known that errors on satellite links employing forward error correction (FEC) schemes tend to occur in clusters. The resulting block error rate is the same as if it was caused by randomly occurring bit errors with an error‐event ratio of BER/α, where α is the average number of errors within a cluster. The factor, α, accounts for the burstiness of the errors and also represents the ratio between the BER and the error‐event ratio. This paper proposes theoretical methods to estimate the factor, α. Using the weight distributions of the FEC codes, we derive a set of expressions for the factor, α, as well as their compact lower bounds. We present lower bounds for various FEC schemes including binary BCH codes, block turbo codes, convolutional codes, and turbo codes. The simulation results show that the proposed lower bounds are good estimates in the high signal‐to‐noise ratio region. Copyright © 2008 John Wiley & Sons, Ltd.     

印度军事卫星通信系统发展概述

在未来信息化战争中,卫星通信将发挥越来越重要的作用,已成为各国竞相争夺的信息制高点。印度从本国实际需求出发,统筹规划,以研发满足国民经济需求的多用途通信卫星为突破口,迅速建成了亚太地区最大的国内通信系统之一。在简要分析印度各军种卫星通信需求和发展现状的基础上,介绍了印度的几个重点卫星通信工程项目,重点论述了"印度国家卫星"(INSAT)系列和"静地星"(GSAT)系列中在役和在研通信卫星的性能和作用,最后总结了印度研发通信卫星系统的经验,期望为相关人员提供参考与借鉴。     

空间辐射环境对卫星光通信系统误码率的影响

为了提高卫星光通信系统的空间抗辐射性能,开展了空间辐射损伤对卫星光通信系统的误码率影响研究。建立了空间辐射损伤的误码率模型,并基于该模型对光源和光电探测器辐射损伤条件下的系统误码率进行了数值计算。结果表明γ射线辐射和质子辐射均能对通信系统误码率造成几个量级的下降,需要增加合理的空间辐射屏蔽单元或者选择空间抗辐射性能较高的零差BPSK工作模式。     

非理想载波同步对多载波直扩系统的性能影响

与单载波直扩相比,多音调制直接序列扩频（Multi-tone DSSS,MT-DSSS）在相同频谱效率下具有更高的处理增益,但非正交子载波的频谱重叠导致其对载波同步更加敏感。分别在频偏及相噪两种情况下对多音调制（MT）系统载波同步误差进行随机过程建模,计算出相关检测判决统计量及平均误码率,并进行仿真验证。结论表明：在频偏条件下,频率估计误差严重干扰每个子载波的解调并对系统误码率有较大影响;不存在频率估计误差时,频偏所造成的载波间串扰（ICI）对系统性能影响较小。在相噪条件下,相同扩频码MT系统的ICI被相关检测时的低通滤波所抑制,使其与单载波直扩具有相同误码率;不同扩频码MT系统的ICI主要由扩频码互相关性引起,而与相噪基本无关。     

基于G.704数字接口转换器的设计

卫星通信地面站的有线信号远端传输,无论同轴电缆还是光纤方式,通常使用E系列标准接口。基于G.704的数字接口转换器可实现基带同步串行数据信号与E1接口信号的互相转换。在简要介绍硬件设计和软件设计基础上,详细阐述了串行接口速率自适应、E1帧时隙选择、收发时钟的产生和先进先出存储器的设计思路,给出了性能测试结果。     

低轨道卫星移动通信系统传播特性的测试与分析

低轨道卫星移动通信是目前新兴的卫星通信系统，国内外对于其电波传播特性的研究目前均处于探索阶段，我们通过在轨运行的低轨道卫星移动通信系统(铱系统)的部分传播特性进行了测试，摸索了对低轨道通信卫星电波特性测试的方法，并对数据进行分析，获得了相关参数，这些参数对了解低轨道通信卫星的电波传播特性并对于我们进行低轨道卫星的设计有参考意义。     

Comparison of advanced coding and modulation schemes for multicarrier satellite communication systems

Digital satellite communication systems use coherent quaternary PSK (QPSK) as the preferred modulation scheme. In recent years, however, the search for bandwidth and power-efficient digital modulation methods has become an active research area. In this paper the performances of combined coding and modulation schemes employing multilevel signal alphabets are considered, in the framework of a system model which reasonably approximates the INTELSAT SCPC system. The main goal of the research was to investigate whether the efficiency of coded modulation schemes and their savings in transmitted power could be maintained in a system environment dominated by interference more than by the additive white Gaussian noise. A second goal was to compare the performance of signals with constant envelope, such as multilevel PSK, with that of signals allowing variations in amplitude, such as multilevel PSK, with that of signals allowing variations in amplitude, such as multilevel QAM. In the paper, we propose a channel model which is reasonably close to the real system, and a method for performance evaluation leading to an estimate of the asymptotic power gain of the modulation systems. The channel model and the method are applied to the analysis of coded 16- and 32- PSK and QAM.     

一种新型中轨卫星移动通信系统设计简介

本文提出了一种新型的中轨卫星移动通信系统设计方案,该系统的特点是采用特殊中的轨赤道轨道卫星星座,所需卫星数目少,成本低,采用波束相对地面静止的凝视天线,避免了由于卫星和地面终端移动造成的通信中断和由此而需的波束切换技术,可靠性强,采用国内技术能技术的通用小卫星平台,制造成本低,投资风险小,文中给出了系统结构,特性参量及工作原理的简单描述,讨论了所需的关键技术和存在的问题。