共查询到17条相似文献,搜索用时 734 毫秒
1.
针对水下通信平台之间通信网络在可靠性、快捷性等方面的不足,提出将水下成熟的通信网络与自组织网络相结合,在特定的区域部署通信网络节点系统对信息进行转发,从而提升了水下通信网络的稳定性与灵活性;研究并设计了水下通信网络节点的系统架构、硬件系统、软件系统;在户外水域相隔10 m的距离分别放置通信节点系统到水下3m的位置,在Matlab7.0平台上完成对对水下通信网络节点信号进行测试,在PC机上应用串口调试助手软件按照初始化的参数:8位数据位、1位停止位、无奇偶校验码、波特率115 200 b/s,测试结果表明:文章系统采样准确,误差低,满足实际需要。 相似文献
2.
Ad Hoc自组网解决了多机器人系统中网络拓扑结构动态变化和数据报文多跳转发的通信问题,决定节点能耗、最优路由和网络信息延迟等网络性能,是多机器人系统网络常用的通信方式。其中AODV协议能较好的在Ad Hoc自组网中适用,但由于多机器人系统中网络拓扑动态变化,传统的AODV协议的网络节点负载情况以及选择路由的准确性方面存在着一定缺陷。在AODV协议基础上,采用负载均衡算法的方式,对路由代价进行优化,以便更好的解决网络节点不均衡、出现拥塞时选路不准确的问题,更好的实现均衡节点能耗、优化路由以及减少网络信息延迟的目标。以NS2为网络仿真平台进行仿真,并对结果进行分析得,与AODV协议相比,改进之后的路由协议的提高了分组投递率、降低了平均端到端时延以及相对路由开销。 相似文献
3.
4.
5.
受水下湍流及水体生物的影响,通信发射光源易产生指向的不确定性,严重增加水下无线光通信的建链难度。针对这一问题,设计了一种基于伺服系统的水下无线光通信系统,该系统基于二维光电转台实现捕获不确定区域扫描,结合CMOS相机实现通信光轴的大视场捕获,最终实现水下无线光通信链路建立。通过实验验证了方案的可行性并对通信单元及伺服单元进行性能测试。实验结果表明,所搭建的系统能够在8.2 s内完成通信光斑的捕获对准,并在通信误码率为1×10-6的情况下,实现50 Mbps的峰值通信速率。 相似文献
6.
7.
8.
《光学学报》2018,(12)
针对蛙人在水下协作执行任务时保持良好通信的需求,研究采用无线光通信技术的节点邻居发现方法。由于光束具有方向性,为了保证邻居发现效果,基于无线光水下传播特性设计半球形通信节点结构,通过成对使用的方式完成对蛙人周围三维空间的覆盖。在半球形节点结构基础上研究采用握手交互信息帧的邻居发现协议,通过发光二极管(LED)逐向扫描发送交互信息的方式,可以不依靠外部定位信息发现相邻蛙人节点。针对蛙人在运动状态下通信链路容易发生中断的问题,研究通信链路的跟踪保持方法。仿真结果表明,在合理选择节点结构参数的情况下,邻居发现方法能有效发现邻居节点,建立通信链路,跟踪保持方法也能显著降低通信链路的中断次数。 相似文献
9.
随着通信技术、嵌入式技术和传感器技术的飞速发展,传感器网络由于具备自组织性、协作性和动态组网变化等特点,在经济生活各方面应用广泛;但目前商用传感网络多为有线的局域网连接,对一些离散型的节点适用性不强,特别是在一些需要远程接入的控制场合就很难实现;针对上述不足,提出了一种基于无线网络与GPRS网络相结合的无线传感网络节点群远程控制方式;离散型终端节点通过433 MHz频点组成无线传感网络,经过本地嵌入式中心节点实现与GPRS网络的异网连接,进而通过手持式终端实现远程监控;实验系统比较了节点群在不同气候条件下数据传输的距离与可靠性,结果表明系统能实现上述两种无线网络的异网数据交换,有效地解决了传感网节点群的远程控制等问题。 相似文献
10.
水声通信网络是水声研究的一个热点问题。由于水下声网络带宽窄、传播延迟大、能量受限等特点,无线电网络中一些成熟的路由协议,如DSDV、AODV等的应用受到了很大的限制。本文结合按需距离矢量(AODV)路由协议和地理位置协议,提出了一种适用于水下网络的路由协议——定向搜索AODV(DSAODV)路由协议。DSAODV协议利用地理位置信息约束路由请求分组(RREQ)寻找路由的范围,降低了路由寻径的开销,减少了网络拥塞。仿真结果表明,DSAODV协议在吞吐量、协议开销等方面都优于AODV协议。 相似文献
11.
Jianxin Ma 《Fiber and Integrated Optics》2014,33(3):163-172
AbstractA full-duplex link implementing alternative wired and wireless access for wavelength-division multiplexing passive optical network is proposed with the uniformed three-tone converged optical signal, which provides a wired or wireless downlink access signal alternatively and an uplink optical carrier. The uplink optical carrier reversed by the converged optical signal makes the hybrid optical node unit free from the optical source. The simulation results show that the full-duplex link with a 10-Gb/s 16-quadrature amplitude modulation (16-QAM) downstream and 5 Gb/s binary upstream can provide both wired access with a bit-error rate below 10?9 and radio-over-fiber-based wireless access with a bit-error rate below 10?7 over 40 km of fiber without an optical source and optical amplifier in the hybrid optical node unit. 相似文献
12.
介绍了物联网的定义及结构;从感知层和网络层角度,探讨了光通信技术(光纤通信和无线通信)在物联网中的应用现状和前景.光纤通信、近距离无线通信、移动通信是物联网开发的基础,制定物联网各个层面上统一的、标准化协议和技术标准是物联网未来发展必须解决的关键和难点. 相似文献
13.
Wireless Sensor Networks consists of interconnected nodes that exchange information wirelessly enabling its deployment in innovative application areas. Network reliability streamline this exchange of information and communication technology to improve the overall performance of the network. The network reliability is categorized as: node reliability and link reliability. In this article, the node reliability is quantified with the help of packet reliability. The packet reliability is enhanced by optimizing the data rate using Bayesian Regularized Neural Network approach, which thus makes the network more reliable and sustainable. The optimization is carried out in three phases: network designing, data rate prediction and reliability evaluation. The network design includes the deployment of sensor nodes for gathering the communication data using NS-2.35. In the next phase, data rate prediction is carried out to enhance the reliability of the network. The reliability of a network is directly influenced by the packet loss ratio. According to research and the network experts, the acceptable threshold limit for the packet loss ratio is 5 percent. The data rate prediction is carried out to minimize the packet loss using the Bayesian Regularized Neural Network algorithm. The packet reliability is measured in terms of packet loss across the wireless network. Finally, a novel framework is presented for evaluating the packet reliability of the wireless network. 相似文献
14.
15.
在水下传感器网络中,有效解决隐藏终端与暴露终端问题,可以提高网络吞吐量和延长网络生存周期。文章提出了一种基于频分多址(Frequency Division Multiple Access, FDMA)方式的双信道载波侦听多路访问(Carrier Sense Multiple Access,CSMA)协议,将水声信道分成控制信道与数据信道,分别进行控制报文与数据报文的传递。仿真结果表明,此协议可以有效地解决由于隐藏终端与暴露终端引起的控制报文与数据报文的冲突,比单信道的CSMA协议性能有较大提升。实验结果表明,在双信道条件下,通信节点可以成功解码在时域上重叠的控制报文与数据报文,具有工程可实现性。 相似文献
16.
The hybrid optical-wireless access network (HOWAN) is a favorable architecture for next generation access network. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. In this paper, the HOWAN architecture is designed based on a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The HOWAN is proposed that can provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects. This paper reports physical layer performance in terms of the bit error rate (BER), eye diagram, and signal-to-noise ratio (SNR) of the communication system. It accommodates 8 wavelength channels with 32 optical network unit/wireless access points (ONU/APs). It is demonstrated that downstream and upstream of 2 Gb/s can be achieved by optical backhaul for each wavelength channel along optical fiber length of 20 km and a data rate of 54 Mb/s per ONU/AP along a 50 m outdoor wireless link. 相似文献
17.
A novel scheme of photonic aided vector millimeter-wave(mm-wave)signal generation without a digital-to-analog converter(DAC)is proposed.Based on our scheme,a 20 Gb/s 4-ary quadrature amplitude modulation(4-QAM)mm-wave signal is generated without using a DAC.The experiment results demonstrate that the bit error rate(BER)of 20 Gb/s 4-QAM mmwave signal can reach below the hard-decision forward-error-correction threshold after a delivery over 1 m wireless distance.Because the DAC is not required,it can reduce the system cost.Besides,by using photonic technology,the system is easily integrated to create large-scale production and application in high-speed optical communication. 相似文献