Design and performance comparison of multiple-token based MAC protocols for optical burst switched ring networks

Optical burst switching (OBS) has been proposed as a new optical switching paradigm for the next generation Internet due to its flexibility and feasibility compared to OCS and OPS. Moreover, serving as a backbone that interconnects a number of access networks, OBS ring topologies have been a good choice for solving the current metro gap problem between core network and access network owning to its simplicity and scalability. In this paper, we provide an insight into the OBS ring network that consists of nodes using TT–TR (Tunable Transmitter–Tunable Receiver). The node architectures with TT–TR may make efficient use of network resources even though traffic pattern, such as IP traffic with self-similarity dynamically change, and can support good expandability. However, all nodes share the limited network resources. This may result in contention such as wavelength contention and transceiver contention leading to burst loss. In order to use the shared network resources fairly and efficiently as well as reducing the resource contention, we focus on the design of medium access control (MAC) protocols based on multiple tokens. Each token is allocated to one wavelength to denote the accessibility of that wavelength, i.e., once the token is captured, the corresponding wavelength can be used to transmit a burst. As tokens hold the key for using wavelengths to transmit bursts, token management including the token release time is crucial in the proposed MAC protocols. Thus, two kinds of multiple-token based MAC protocols with different token release times are proposed: token release after transmitting burst (TRTB) and token release after transmitting control header (TRTC). Each of them is classified into two schemes called TRTB/TRR and TRTB/RCA and correspondingly TRTC/TRR and TRTC/ RCA. RCA stands for receive collision avoidance. The target is to increase the performance while reducing the processing overhead at each node. The performance of the TRTB and TRTC protocols are evaluated and compared in terms of queuing delay, burst loss rate, and channel utilization by OPNET simulation. The effects of various design parameters are also investigated through simulation in order to evaluate their scalability. In all the proposed schemes, tokens are just used to denote the accessibility of each wavelength. Finally, as an alternative, we also propose a new scheme based on the TRTC protocol called TRTC/CAT (collision avoidance by tokens) to avoid contention by using tokens.

一种基于ARM和FPGA的可重构MAC协议设计

为了在实际信道条件下研究AdHoc网络MAC协议,克服商业网卡芯片和理论仿真等带来的局限性,搭建了基于ARM和FPGA相结合的硬件平台,设计与实现了基于CSMA／cA的可重构MAC协议,并进行了仿真测试,验证了该协议设计的正确性。对AdHoc网络MAC协议的实用化提供有益的参考。     

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。     

APON接人系统的一个介质访问控制协议

作为共享介质的接入网络,APON需要介质访问控制协议用于协调各终端对介质的存取.本文提出了一个符合ITU-T建议的MAC协议,采用了时延分优先级,对高优先级的实时业务按照的均匀间隔的原则分配带宽,低优先级业务的带宽按次序循环分配.上行帧长度根据处于连接的用户数动态变化,各终端的带宽申请时隙由系统动态分配.最后给出了由该协议确定的网络性能的计算机仿真结果.     

无线自组网竞争类MAC协议分析及研究

无线自组织网络是一种无基础设施的移动网络,并且每个节点的业务多以突发业务为主,因此信道资源分配适用于采用竞争方式。本文在对无线自组网各种典型竞争类MAC协议进行分析及探讨的基础上,采用Opnet仿真建模环境,创建出各协议的状态分析模型,并在此基础上对各协议的性能优劣进行了比较总结。论文对无线自组网各协议仿真建模研究及选择高效适用的MAC技术方案具有实际参考价值。     

QoS for wireless sensor networks: Enabling service differentiation at the MAC sub-layer using CoSenS

Providing service differentiation in wireless sensor networks while proposing simple and highly scalable solution is a challenging problem. We retain the use of CSMA/CA as access protocol because of its simplicity, versatility and good scalability properties. We developed CoSenS, a Collect then Send burst Scheme, on top of it to address its weaknesses while facilitating the implementation of scheduling policies. In this article, we propose a simple and scalable service differentiation solution; we implement fixed priority and earliest deadline first on top of CoSenS. The simulation analysis shows that our solution self-adapts to the traffic variation and greatly enhances end-to-end delay, reliability and deadline meet ratio for urgent traffic while not degrading best effort traffic compared to IEEE 802.15.4 original protocol and IEEE 802.15.4 implementing these scheduling policies. Additionally, CoSenS is implemented and tested on motes. The real experimentation results validated our simulation analysis.     

一种改进的宽带卫星网络MAC协议

为了提高宽带卫星网络上行信道资源的利用率,同时保障多媒体业务的不同服务质量要求,需要采用合适的媒体接入控制协议。BTDAMA可以显著减少自相似业务的等待时延,并且提高了资源利用率。但它没有区分业务类型,不能保证高优先级业务的服务质量,也造成了一定程度上资源的浪费。在BTDAMA的基础上提出了一种基于业务优先级的带宽分配算法,针对不同的业务类型采用不同的分配方案,不仅保证了各类业务的服务质量,同时提高了资源利用率。     

Hopping control channel MAC protocol for opportunistic spectrum access networks

Opportunistic spectrum access （OSA） is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access （CHMA） protocol,we introduce a hopping control channel medium access control （MAC） protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users＇ occupancy of the channel,we use a primary user （PU） detection model to calculate the channel availability for unlicensed users＇ access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.     

基于FPGA无线传感器网络MAC控制器的设计

给出了一种由FPGA实现的无线传感器网络MAC控制器的设计方法,采用自顶向下的方法设计各个模块,并在QuartusⅡ 8.0完成了仿真,该控制器主要支持IEEE802.15.4协议.测试结果表明,该MAC控制器支持20～250 kb·s<'-1>数据传输速率,适应IEEE802.15.4协议要求.     

MAC Protocol of a Next-Generation MAN Architecture Based on WDM and All-Optical Packet Switching

As media converge to the Internet, MANs will face new demands not only in terms of bandwidth, but also in terms of services. We describe a next generation MAN architecture that has been designed within Dutch project Flamingo. Based on all-optical packet switching, this architecture supports one-to-one, one-to-many and many-to-one communications in the optical domain. Specifically, we focus on the MAC layer of the network. We describe the access and fairness protocols and explain how the all-optical nature of the architecture affects the design of these protocols. We also discuss some performance results that have been obtained via simulation.     

SDMAC: Selectively Directional MAC protocol for wireless mobile ad hoc networks

Using directional antennas in wireless mobile ad hoc networks can greatly improve the transmission range as well as the spatial reuse. However, it will also cause some problems such as deafness problem and hidden terminal problem, which greatly impair the network performance. This paper first proposes a MAC protocol called Selectively Directional MAC (SDMAC) that can effectively address these problems and significantly improve the network throughput. Then two improvements on SDMAC are proposed. The first one is to improve the network throughput by scheduling the packets in the queue (a scheme called Q-SDMAC), thus the head-of-line (HOL) blocking problem can be addressed. The second one is to relax the assumption that each node knows the relative directions of its neighboring nodes and use caches to buffer those relative directions (a scheme named Q-SDMAC using cache). Extensive simulations show that: (1) SDMAC can achieve much better performance than the existing MAC protocols using directional antennas; (2) The network throughput can be significantly improved by scheduling the packets in the queue; (3) Using caches can still achieve high network throughput when nodes are moving; and (4) Network throughput decreases when directional antennas have side lobe gain.

认知无线电网络的MAC协议机制

针对认知无线电网络可用信道资源随时间和空间环境变化的特点,分析了认知无线电网络MAC协议面临的问题,提出了一种基于全局控制信道的MAC协议方案,在此基础上阐述了两种接入方式及相应适用场合,实现了认知无线电节点对可用信道资源变化的感知,可为认知无线电MAC协议研究及应用提供参考.     

异质节点分离CRSN中MAC协议设计与性能分析

认知无线传感器网络(CRSN)是一种将认知无线电(CR)技术引入传统WSN中的新型网络,具有一定的应用价值和发展前景.然而,CRSN中的认知功能带来的额外能耗和处理要求及其高成本实现,阻碍了它的进一步发展及应用.基于此,提出将认知功能迁移到另外一类节点——认知节点,并使其拥有较强的处理能力和能量收集能力.认知节点与普通传感器节点按照一定比例进行部署,组成另外一种新型网络——异质节点CRSN (HT-CRSN),这种新型网络能够提高网络性能并降低部署成本.并提出了一种能够适用于这种异质节点传感器网络的工作时序及其一系列可行性的MAC协议(FBP等).通过对所提MAC协议的能耗分析,说明可以通过调整两类异质节点的部署比例和能量收集速率均衡两类异质节点的能耗,进而提高网络生命周期.     

An efficient media access protocol for packet-switched wavelength-division multiplexed photonic networks

A reservation-based protocol based on a Pipelining Cyclic Scheduling Algorithm (PCSA) is proposed for packet-switched single-hop photonic networks. This protocol contains a mechanism to avoid contention at the receivers. Packets arrive in order and the transmission delay and its variations are optimized. The effects of propagation delay and processing time are almost compensated for by a pipelining technique. Analytical models and analysis are developed. The transmission delay is calculated as a function of the offered load, the number of nodes, propagation delay and processing time. Finally, the results of the analysis and simulations are compared.     

WDM城域环网中支持可变长分组的节点结构及MAC协议设计

WDM城域环网在升级时,信道数可能是不变的.本文基于此设计了一种新颖的节点结构,它由固定发射器和一组固定接收器组成.基于该结构,文中给出了支持可变长分组的时隙结构及MAC协议.由于实现MAC协议毋需专用波长信道,提高了资源利用率.理论分析和仿真结果证明了本文设计方法可以充分利用空间重用能力,获得很好的网络流量,分组排队时延及分组丢弃率.对于信道数较多,或者网络在升级时信道数也可能变化的情况,本文建议采用固定发射器,一组"准"调谐的接收器结构.该方案可在实现复杂度,网络性能及成本间取得折衷.     

一种基于功率控制的无线传感器网络MAC协议

提出了一种基于功率控制机制的无线传感器网络MAC协议 Distance Prediction Power Control MAC (DPPC-MAC).DPPC-MAC协议基于目前十分成熟的SMAC协议[1-2],引入了功率控制机制以降低数据包发送时的能耗,并且提出了一种新的通过功率预测距离来解决暴露终端和隐藏终端的方法.仿真结果表明,DPPC-MAC能有效降低网络能耗,同时吞吐量性能也得到了一定的改善.     

基于令牌的无线传感器网络MAC协议

为了更进一步减少信道冲突和网络能耗,提出一种基于令牌的链式无线传感器网络MAC协议.协议自定义信标帧和数据帧,在传感器节点完成时间同步后,以信标帧中的令牌为控制信息对相邻两个传感器节点进行收发控制,实现数据从链尾节点到链头节点的顺序上传.研究表明,该协议不仅能够满足系统的稳定性要求而且能够有效降低功耗.     

A MAC Protocol for IP Differentiated Services in a WDM Metropolitan Area Network

This paper presents a Media Access Control (MAC) protocol for a WDM passive optical star. The protocol supports scalable service differentiation for Internet traffic in the spirit of the IETF's Diffserv architecture. We describe the functional elements of the protocol (signaling, arbitration, service disciplines and buffer management techniques) and the way they interact to support the Diffserv's Expedited Forwarding (EF) PHB and Assured Forwarding (AF) PHB group, where PHB stands for Per-Hop-Behavior. Extensive simulation results give quantitative estimations of the performance of the protocol under combined EF/AF traffic.     

基于OPNET的水声通信网MAC层协议的研究

AC（Multiple Access）协议是水声通信网络的重要研究内容,利用OPNET网络仿真软件对ALOHA协议和MACAW协议下水声通信网络的性能进行仿真研究,分析比较这两种协议在不同业务量下的网络性能。仿真结果表明,在水声通信网络中,MACAW协议的性能优于ALOHA,但两者均可应用于低数据业务量网络中。     

IEEE802.11与高级红外无线AIr MAC协议的性能比较

红外线作为室内通信无线传输媒质,具有低成本、低功耗等特点.本文描述 了IEEE 802.11红外局域网媒质访问控制协议（MAC）和红外数据协会（IrDA）提出的高级红外媒质访问控制层协议（AIr MAC）;研究了两种协议性能估计模型并利用OPNET仿真工具对IEEE 802.11 MAC与高级红外AIr MAC接入性能进行了仿真验证.通过对两种MAC协议接入方式、吞吐量性能估计模型以及吞吐量性能仿真结果进行比较分析,总结了IEEE 802.11红外局域网媒质接入协议和高级红外媒质接入协议之间的不同之处.