影响机间数据链组网协议设计的主要因素分析

指出了机间数据链组网协议的设计目标,对机间数据链网络常用拓扑结构及适用的 多址接入方式进行了阐述,对影响机间数据链组网协议设计的主要因素进行了详细分析, 给出了机间数据链组网协议的设计思路和流程,并对今后机间数据链组网协议的发展进行展 望。     

基于SPMA协议的混合式信道负载统计方法

战术瞄准网络技术系统作为美军新一代战术数据链系统,在链路层面以"全双工"通信为基础实现了基于优先级概率统计的多址接入协议SPMA(Statistic Priority-based Multiple Access)。战术数据链的链路层协议或称MAC协议描述了节点接入无线信道的规则,采用合适的MAC协议,能够更合理地分配有限的无线带宽资源,是战术数据链的关键技术之一。本文主要对统计优先级多址接入(SPMA)协议的信道占用状态进行研究,从物理层和网络层两方面对信道占用状态进行统计,然后采用预测技术有效的估计实际的信道占用状态,设计了一种准确的混合式信道负载统计方法,有效地降低了信道冲突,保证了数据发送的实时性和高优先级数据较高的成功传输概率。     

一种新的支持定向天线应用的忙音和功率控制多址接入协议

该文针对移动Ad Hoc网络(MANET),提出了支持定向天线应用的忙音和功率控制多址接入协议(BT-DMACP)。协议充分考虑到定向天线应用中存在的特殊隐藏终端问题和旁瓣干扰,利用RTS/CTS短分组对话机制、定向忙音信号和基于信噪比门限的功率控制策略,对数据分组的定向发送功率进行实时调整。同时为准确估计接收节点处的最大干扰功率,设计了自适应干扰功率估计算法。仿真结果证明,BT-DMACP协议能有效支持定向天线在MANET中的应用,在降低了系统功耗同时,具有很高的信道利用率。     

一种基于定向天线的自组网多址接入协议

文中提出一种基于定向天线的自组织网多址接入协议DA-STDMA。该协议利用方向性天线定向波束增益特性,保证在高速可靠传输条件下,提升系统的容量,同时可以防止信息截获,提升系统的抗干扰性能。经过理论计算,DA-STDMA协议在信道利用率上与采用全向天线相比有显著提高。文中建立了DA-STDMA协议仿真模型,通过对比空间复用度、网络吞吐量等系统性能,DA-STDMA协议利用定向天线比全向天线性能有明显提升。同时仿真研究也表明,定向天线的定位算法对整个系统建链的收敛时间产生一定影响。     

卫星高速数据链中MF-TDMA协议改进研究

针对卫星高速数据链对带宽以及高速数据传输需求较高的特点,提出将MF-TDMA多址接入协议应用到卫星高速数据链系统中。运用排队理论建立模型,对协议平均等待时延以及吞吐量进行了理论分析,引入了优先级机制,推导了在时隙均匀分配条件下该协议及其改进型的平均等待时延公式。通过计算机仿真表明,该协议在系统保持较高吞吐量的基础上能够保证较低的平均时延,同时满足高优先级用户的需求。     

机间数据链核心问题的分析与探讨

指出了机间数据链的重要性,阐述了低传输延迟特性、高数据传输率、低截获率、高抗干扰能力、动态组网等特征对系统的要求.对频率选择、窄带多波束天线设计、信道接入协议等核心问题进行了较深入的分析,指出了解决方案和途径,并讨论了建立网络协议开发平台的意义及方法.     

基于ALOHA的宽带接入技术研究

本文研究了扩频技术与ALOHA技术相结合的扩频ALOHA(SAMA)多址接入协议的性能,推导了通用的ALOHA系统吞吐性能表达式.研究结果表明,这种宽带随机多址接入技术能够大大提高网络吞吐量,显著改善分组传输时延,从而有利于满足未来无线数字网络对各种业务支持和服务质量的要求.     

一种关于分布式网络调度协议的研究

多址接入控制协议是网络的重要组成部分,特别是在分布式网络中,它直接影响网络的性能。随着技术的发展,如何将物理层和多址接入层有效的结合起来,如何在接入时可以有效的利用资源,这些因素对网络性能上的提升具有重要意义和价值。本文研究了高通公司提出的Flash Lin Q通信系统,并且详细介绍了Flash Lin Q通信系统所采用的分布式调度协议,该协议是一种高效的并且有效利用空间资源的多址接入协议,相比于RTS/CTS机制的CSMA/CA机制的多址接入协议有较大的增益。协议可以在信号覆盖范围之内实现多条链路的并行传输,增加了网络的吞吐量,改善了网络的性能。     

第三代短波网络自适应多址接入算法的研究

设计一种基于第三代短波链路自动建立(3G-ALE)技术的自适应多址接入算法.文中分析3G-ALE基本多址接入算法及改进型算法的缺点,设计依据业务长、短不同而进行自适应接入的TA-CSMA算法,建立网络模型进行计算机仿真验证.仿真结果表明,TA-CSMA算法可以使网络呼损率及信道占用率明显降低,使网络吞吐量有较大提高.TA-CSMA算法是适合短波自组织网络的一种高效的多址接入协议.     

基于QualNet的无人机数据链时延仿真

概述了无人机数据链的网络组成,介绍了通信网络仿真软件QualNet的功能特点及其架构,并在该软件平台下建立无人机数据链时延仿真模型,分析远近程无人机在不同MAC信道接入协议下的平均端到端时延和平均抖动.仿真结果表明,设计无人机数据链时可优先采用TDMA接入协议.     

采用定向天线Ad Hoc网络MAC协议关键问题研究

介绍基于定向天线的MAC协议,阐述使用定向天线所面临的隐藏终端、暴露终端以及聋节点问题。重点分析定向天线的MAC协议造成隐藏终端和暴露终端的原因以及解决这些问题的相应策略,在此基础上提出了新的改进CSMA协议。通过仿真表明,改进CSMA协议能提高基于定向天线Ad Hoc网络的整体性能。     

Addressing deafness and hidden terminal problem in directional antenna based wireless multi-hop networks

We address deafness and directional hidden terminal problem that occur when MAC protocols are designed for directional antenna based wireless multi-hop networks. Deafness occurs when the transmitter fails to communicate to its intended receiver, because the receiver’s antenna is oriented in a different direction. The directional hidden terminal problem occurs when the transmitter fails to hear a prior RTS/CTS exchange between another pair of nodes and cause collision by initiating a transmission to the receiver of the ongoing communication. Though directional antennas offer better spatial reuse, these problems can have a serious impact on network performance. In this paper, we study various scenarios in which these problems can occur and design a MAC protocol that solves them comprehensively using only a single channel and single radio interface. Current solutions in literature either do not address these issues comprehensively or use more than one radio/channel to solve them. We evaluate our protocol using detailed simulation studies. Simulation results indicate that our protocol can effectively address deafness and directional hidden terminal problem and increase network performance.     

定向Ad hoc网络MAC组网技术研究

定向天线利用数字信号处理技术产生空间定向波束,将发射信号能量集中在某一个或者某些特定的方向上进行辐射,其应用于传统的Ad hoc网络中能够有效减少相邻节点间的互干扰,并能通过增加同时传输的节点对数达到显著提升网络空间复用率和容量的目的。首先简单介绍了定向天线和定向通信特点,然后对定向Ad hoc网络MAC层组网关键技术进行了综述,并对定向邻居发现协议、空分TDMA动态时隙分配机制、定向波束对准与跟踪技术等进行介绍和梳理,最后总结现有研究不足并指出未来重点研究方向。     

A MAC protocol for the mixed scenario of omnidirectional and directional nodes in an ad hoc network

In ad hoc networks, directional antennas offer many benefits compared with classical omnidirectional antennas. Those include significant increases in spatial reuse, coverage range, and subsequently network capacity as a whole. Most of the proposed directional medium access control methods assume that all the nodes in the network have homogeneous antenna types. However, it is quite unusual that a sudden change will occur, and every laptop, palmtop, computer, and other similar device will be turned into a directional antenna holding device. There will always be a possibility of heterogeneous antenna used in the deployed nodes of the network. In this paper, we have proposed a medium access control protocol that deals with the new challenges introduced into heterogeneous networks in the form of deaf and hidden node problems. Using Optimized Network Engineering Tools 16.0, we have simulated three ad hoc network scenarios. These scenarios have different ratios of omnidirectional and directional nodes. We evaluated the performance of these scenarios by varying the ratio. We found that when we increase the directional nodes in the network, the performance increases. Copyright © 2013 John Wiley & Sons, Ltd.     

Performance Analysis of Directional CSMA/CA for IEEE 802.15.3c under Saturation Environments

In this paper, the directional carrier sense multiple access/collision avoidance (CSMA/CA) protocol in the immediate acknowledgement mode for IEEE 802.15.3c is analyzed under saturation environments. For the analysis, a sensing region and an exclusive region with a directional antenna are computed probabilistically and a Markov chain model in which the features of IEEE 802.15.3c and the effects of using directional antennas are incorporated is analyzed. An algorithm to find the maximal number of concurrently transmittable frames is proposed. The system throughput and the average transmission delay are obtained in closed forms. The numerical results show the impact of directional antennas on the CSMA/CA media access control (MAC) protocol. For instance, the throughput with a small beamwidth of antenna is more than ten times larger than that for an omnidirectional antenna. The overall analysis is verified by a simulation. The obtained results will be helpful in developing an MAC protocol for enhancing the performance of mmWave wireless personal area networks.     

Neighbor initiated approach for avoiding deaf and hidden node problems in directional MAC protocol for ad-hoc networks

In this paper we propose a MAC called “Neighbor Initiated Approach for avoiding Deaf and Hidden node problems in directional MAC protocol for Ad Hoc networks”, which takes advantage of the multi beam smart antennas. Through the antenna, a node can simultaneously transmit/receive a packet to/from all the directions around it. Thus the antenna switches itself in transmission and reception mode. In our scheme all transmission and reception will be directional. We discussed the hidden and deaf node problems with directional MAC and proposed the scheme to overcome those shortcomings. Our scheme has been inspired by the IEEE 802.11, which includes a new scheme to inform its neighbors who was deaf due to other communication. Moreover, the simultaneous transmission of the RTS/CTS through it’s all beams prevent the hidden node problem. In our scheme the idle nodes stay in reception mode for sensing the channel through its M non overlapping beams, as a substitute of omnidirectional antenna. It prevents the hidden node problem due to asymmetry in gain. We have simulated our scheme by OPNET 16.0, and compared our results with CDR MAC, DMAC and IEEE 802.11 protocols. Our results show that NIADH performs better than that of the existing protocols in majority of the scenarios.     

Construction of the WOR Transmitter and Directional Antenna System

Radio station WOR in New York City recently moved its 50 kW AM transmitter and directional antenna system from Carteret, N. J. to Lyndhurst, N. J. This paper describes the facilities and design, and the problems encountered in moving to a swamp location in the midst of 12 other radio stations. While not all problems are applicable to every new directional antenna system, many of them are common. The paper details recommendations on construction of a transmitter plant and a directional antenna system, the solution of problems, and pitfalls to avoid.     

基于TDMA和定向天线的无线Mesh网络广播技术

传统Mesh网络实现的广播过程中存在节点之间冲突干扰、广播延时大和信道利用率不高等问题.采用TDMA接入协议与多接口的定向天线,优化了邻居发现过程和信道分配过程.在QualNet软件上进行仿真,并与其他算法进行性能对比,仿真和对比结果表明本广播过程相较于传统广播过程,减少了邻居发现时间,提高了时隙的复用率和信道利用率,...     

基于定向天线的移动自组网路由协议研究

同等功耗下,定向天线能够产生更高的增益,提供更大的传输范围,提高网络的空间复用度和吞吐量,天线选择的方向性又降低了邻近结点之间的相互干扰,采用定向天线能够给移动自组网带来潜在性能的提高。对基于定向天线的移动自组网路由协议进行研究,简单介绍了定向天线,总结了引入定向天线产生的路由问题,对现有的一些典型定向路由协议进行了分类、介绍和比较,最后对引入定向天线带来的好处进行了分析。