TP-Satellite: A New Transport Protocol for Satellite IP Networks

As a result of the exponential growth of the worldwide Internet, satellite systems are used to support broadband Internet access. Existing TCP protocols perform very well for Internet access on wired networks. However, in the case of satellite channels, due to the effects of high bandwidth asymmetry, long propagation delay, high sporadic bit error rate (BER) and burst errors, TCP performance degrades significantly. In this paper, a new end-to-end transport protocol, TP-Satellite, is proposed for satellite IP networks. TP-Satellite replaces the traditional slow start algorithm with a novel super start algorithm. In order to distinguish congestion events from link errors, a new scheme is introduced, which is based on alternate transmission of different class priority packets. Bandwidth asymmetry problems are addressed by the adoption of a modified negative acknowledgement (M-NACK) strategy, which periodically sends M-NACK packets. Simulation results show that TP-Satellite enhances the throughput performance on the forward path, reduces the bandwidth used in the reverse path, and offers a fair share of network resources.     

MANET中一种新的基于多包接收的媒体接入控制协议

提出了一种新的基于多包接收的MANET媒体接入控制协议.该协议利用信道多包接收的特性,结合功率控制和协议的跨层设计,可选取信道增益较大的节点接入信道.实验结果表明,在业务量较大时,新协议在提高网络吞吐量的同时,减小了能量消耗.     

AeroMTP: A fountain code-based multipath transport protocol for airborne networks

Airborne networks(ANs) are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation.Compared to ground networks, ANs have some unique attributes including high node mobility, frequent topology changes, mechanical and aerodynamic constrains, strict safety requirements and harsh communication environment.Thus, the performance of conventional transmission control protocol(TCP) will be dramatically degraded in ANs.Aircraft commonly have two or more heterogeneous network interfaces which offer an opportunity to form multiple communication paths between any two nodes in ANs.To satisfy the communication requirements in ANs, we propose aeronautical multipath transport protocol(Aero MTP) for ANs, which effectively utilizes the available bandwidth and diversity provided by heterogeneous wireless paths.Aero MTP uses fountain codes as forward error correction(FEC) codes to recover from data loss and deploys a TCP-friendly rate-based congestion control mechanism for each path.Moreover, we design a packet allocation algorithm based on optimization to minimize the delivery time of blocks.The performance of Aero MTP is evaluated through OMNe T++ simulations under a variety of test scenarios.Simulations demonstrate that Aero MTP is of great potential to be applied to ANs.     

认知协作Ad Hoc网络中分布路由跨层控制策略

认知无线电Ad Hoc网络中,吞吐量最大化是一个关键的挑战.为了实现这一目标,协同传输是前景看好的技术,利用在每个空间节点的多样性中继链路以增加性能,特别是在无线环境中由于不同的信道质量、有限的能源和带宽资源,这种想法是有吸引力的.文章在分布式动态环境下,研究了联合动态路由.中继分配和频谱分配分布式和本地算法,提出了一...     

无线传感器网络的异构性研究

随着无线通信技术和微电子技术的快速发展,低成本、高度集成和自组织的无线传感器网络将会逐渐普及.首先总结归纳了无线传感器网络异构性的几种表现形式,如计算能力异构性、节点能量异构性、链路异构性及网络协议异构性,然后介绍了异构无线传感器网络层次网络体系结构和两种适用于无线传感器网络的标准.最后对无线传感器网络的安全问题进行简单探讨.     

移动Ad Hoc网络中一种有效多址协议的性能仿真

基于有效竞争预约接入、无冲突轮询传输的思想,本文提出了支持节点移动性和多跳网络结构的依据用户妥善安排的多址接入(UPMA)协议,并使用网络仿真工具OPNET评估了它的多址性能。仿真结果表明,该协议显著提高了多跳网络的业务传输效率。     

A Novel Onboard-gateway-based Mechanism to Improve TCP Performance in Aeronautical Satellite Networks

The IP-based networks on aircraft serve to support Internet services via satellites. However, in aeronautical satellite hybrid net- works,the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism (OGBM), which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver’s advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to 1 improves TCP performance in aeronautical satellite networks.     

基于TDMA的联合自适应B-ACK与ACM的MAC协议

采用自适应块确认（B-ACK）减轻频繁握手造成的长延时,通过自适应编码和调制（ACM）来克服 吞吐量下降的问题,提出了基于时分多址（TDMA）的联合自适应B-ACK 和ACM 的MAC 协议,根据误包率 变化,自适应地调整节点接入网络的策略,从而解决现阶段航空无线协同网络存在的吞吐量低和延迟大的问题。     

Wireless sensor networks: scheduling for measurement and data reporting

An optimal load allocation approach is presented for measurement and data reporting in wireless sensor networks with a single level tree network topology. The measurement problem investigated involves a measurement space, part of which can be sampled by each sensor. We seek to optimally assign sensors part of the measurement space to minimize reporting time and energy usage. Three representative measurement and reporting strategies are studied. This work is novel as it considers, for the first time, the measurement capacity of processors and assumes negligible computation time which is radically different from the traditional divisible load scheduling research to date. Aerospace applications include satellite remote sensing and monitoring and sensor networks deployed and monitored from the air.     

一种移动卫星网络最小费用切换算法(英文)

For mobile satellite networks, an appropriate handover scheme should be devised to shorten handover delay with optimized application of network resources. By introducing the handover cost model of service, this article proposes a rerouting triggering scheme for path optimization after handover and a new minimum cost handover algorithm for mobile satellite networks. This algorithm ensures the quality of service （QoS） parameters, such as delay, during the handover and minimizes the handover costs. Simulation indicates that this algorithm is superior to other current algorithms in guaranteeing the QoS and decreasing handover costs.     

基于 FAMA-NCS的高速分组传输网络性能

FAMA-NCS协议是无线自组网络中数据链路层的关键组成部分。在对FAMA—NCS协议的关键技术分析和信道访问机制模拟变量的基础上，根据网络中节点的重要信息排序，通过对其退避算法进行报文长度的调整，实现了对吞吐量的提升并减小了数据分组的传播时延。     

嵌入式无线VOD系统方案设计

通过一个嵌入式无线视频点播方案的设计与实现,展示了远程教育中移动学习的一个典型应用.通过支持IEEE802.11b无线网络协议和MMS协议,在带CF无线网卡的Intel PXA270硬件平台上,采用支持多种编码格式的Mplayer播放器,并对Konqueror浏览器加入MMS协议支持.通过对整个方案中若干关键技术的设计与实现,建立了原型系统,为以后进一步的推广和应用打下了良好基础.     

传感器网络MAC协议能量有效性的研究与MATLAB的仿真

无线传感器网络由于能量受限,传感器节点的生存周期取决于节点的能量消耗。本文分析了典型的S-MAC协议和T-MAC协议,研究了这些协议的工作原理。针对节能问题,建立了能量消耗的数学模型。对无线传感器网络的MAC协议,进行了MATLAB软件仿真,做出了关于能耗问题的曲线图,仿真结果表明在同等条件下T-MAC协议耗能较少,且能较好的满足通信的时延性。     

无线传感器网络节点的研究与设计

无线传感器网络节点的设计,对于构成一个实际的无线传感器网络应用系统具有重要意义。本文在对ZigBee协议和无线传感器网络体系结构进行论述的基础上,设计了一种基于ZigBee协议和PIC18F4620单片机的无线传感器网络节点。该节点采用了一款符合IEEE802.15.4标准的ZigBee无线网络芯片CC2420,通过PIC18F4620单片机的SPI接口实现单片机和ZigBee芯片的通讯。文中对该节点开发设计过程中的主要问题进行了较详细的论述,对传感器网络设计与应用具有参考价值。     

Cooperative Routing for Maximizing Network Performance of Wireless Networks

To greatly increase spectral efficiency and improve network performance in wireless networks,a novel cooperative routing algorithm,namely maximum throughput cooperative routing(MTCR) algorithm,is proposed.According to cooperative link model,throughput analysis is presented to evaluate performance improvement in the process of exploiting cooperative commu-nication from physical layer to higher layer.Taking the throughput improvement as performance metric,a cooperative relay se-lection scheme is developed.Finally,based on the route constructed by adaptive forwarding cluster routing(AFCR) algorithm,each node on the route selects the optimum cooperative node from all the potential cooperative nodes to construct the coopera-tive link with maximum throughput so that cooperative route with maximum network throughput from source to destination can be set up.Simulation results show that compared with the noncooperative routing algorithm and minimum power selection de-code-and-forward(MPSDF) routing algorithm,the proposed algorithm can obviously improve network throughput in the pres-ence of low transmission power,large number of nodes and high spectral efficiency.     

面向互联飞机的空天地网络一体化融合研

随着数字化技术的发展，民用飞机会在飞行各阶段产生大量数据，这些数据的利用及处理将提升飞机运营的经济性、安全性与舒适性。为了适应未来互联飞机对海量数据交换与传输的迫切需求，满足民用飞机对无线通信服务质量(QoS)的要求，有必要充分利用并合理分配多种现有和未来的空天地无线通信链路资源。分析了互联飞机的概念、生态系统及其对空天地网络的网络需求，研究了地面异构移动互联网采用的紧耦合和松耦合两种融合方法，采用了网络体系融合、IP网络和非IP网络融合及终端融合等多种融合手段，提出了适应于多种通信链路与网络体系特点的一体化空天地无线通信链路的融合架构，并对网络协议栈、网络安全以及集成验证提出了初步考虑。     

卫星轨道误差的相关性

卫星的轨道误差是卫星测控中需加以约定的重要指标之一,其常用的表示方法主要有Kepler轨道根数形式和RTN投影形式。本文推导了RTN形式的卫星位置、速度误差与Kepler根数误差间的关系,给出了近圆轨道中RTN形式位置、速度误差间的定量关系,分析了RTN形式位置误差约束下Kepler根数误差的相关性,并分别给出了验证算例。该结果可用于分析确定卫星轨道误差指标,使其彼此匹配。     

无线传感器网络时间同步协议动态切换机制

针对当前无线传感器网络时间同步协议通用性差的问题,提出了基于主动编程思想的时间同步协议动态切换机制,设计了能够动态适配的时间同步协议切换框架,重点讨论了节点间相互通信、时间戳标记、协议切换、本地时间与全局时间的转换等4个关键问题,并且在TinyOS（Tiny Operating System,微操作系统）平台上对新机制进行了仿真验证,比较了新机制同2种主流时间同步协议之间的性能差异.仿真结果表明：新机制能实现时间同步协议的动态配置,提高协同效率,节省切换开销,具有良好的应用前景.     

Spread-Spectrum Multiple Access Using Wideband Noncoherent MFSK

Two spread-spectrum multiple access systems which usewideband M-ary frequency shift keying (FSK) (MFSK) as theprimary modulation are presented. A bit error rate performanceanalysis is presented and system throughput is calculated for sample C band and Ku band satellite systems. Sample link analyses areincluded to illustrate power and adjacent satellite interferenceconsiderations in practical multiple access systems.     

Green UAV communications for 6G: A survey

Unmanned Aerial Vehicles (UAVs) have received a wide range of attention for military and commercial applications. Enhanced with communication capability, UAVs are considered to play important roles in the Sixth Generation (6G) networks due to their low cost and flexible deployment. 6G is supposed to be an all-coverage network to provide ubiquitous connections for space, air, ground and underwater. UAVs are able to provide air-borne wireless coverage flexibly, serving as aerial base stations for ground users, as relays to connect isolated nodes, or as mobile users in cellular networks. However, the onboard energy of small UAVs is extremely limited. Thus, UAVs can be only deployed to establish wireless links temporarily. Prolonging the lifetime and developing green UAV communication with low power consumption becomes a critical challenge. In this article, a comprehensive survey on green UAV communications for 6G is carried out. Specifically, the typical UAVs and their energy consumption models are introduced. Then, the typical trends of green UAV communications are provided. In addition, the typical applications of UAVs and their green designs are discussed. Finally, several promising techniques and open research issues are also pointed out.