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EPON系统中MAC算法的仿真设计 总被引:1,自引:0,他引:1
在分析EPON系统中MAC协议和算法的基础上进行了数学建模及仿真实验,提出了基于OLT的带宽分配算法.该算法可充分使用EPON的带宽资源,为在EPON的MAC层设计上提供了参考. 相似文献
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基于固定长度的EPON帧结构和MAC协议设计 总被引:2,自引:0,他引:2
以太无源光网络(EPON)已成为国内外接入网技术的最新研究热点,而EPON标准正在制定。针对EPON系统的核心关键技术之一的上行信道带宽动态分配问题,参照APON的G.983建议,提出了一种基于固定长度的EPON上下行传输帧结构和媒质接入控制(MAC)协议。该方案以APON为借鉴,将EPON中以太网帧长度固定下来;考虑到实时业务对时延敏感,MAC协议对实时业务实行优先带宽分配,对其他类型业务则采用动态带宽分配方案。最后通过建模防真分析了协议的信元时延(CD)特性。 相似文献
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《电子科技文摘》1999,(5)
Y98-61391-302 9906640高速无线网络的已有 MAC 协议的述评=A review ofproposed MAC protocols for high-speed wireless networks[会,英]/Renaud,A.& Blight,D.//1997 IEEE Con-ference on Communications,Power and Computing-Wescanex.—302~305(MaG)本文在媒体接入控制(MAC)协议的介绍和简单综述之后,对有关高速无线系统的 MAC 协议和带宽分配策略方面的现有文献进行了述评。评述了从简单Aloba 型算法到相当复杂的轮询方案的四种协议。还试图对这些协议在它们的技术性能的基础上进行比较。参4 相似文献
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可见光通信作为一种新兴的无线通信技术,具有极大的发展前景。介绍了IEEE 802.15.7标准(草案),该标准对MAC协议进行了详细的定义。标准中提出的MAC协议的功能有很多,可以从信道接入、GTS分配、信道分配、合作通信等方面对MAC协议进行优化,通过对这些优化技术的研究讨论,进一步改善可见光通信的性能。 相似文献
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HFC(Hybrid Fiber Coaxial)作为一种主要接入网络,近年来受到了越来越深入的研究.HFC网络具有独特的树形-分支结构,其上、下行信道在频段上相互隔离,下行信道带宽较大,是一对多的广播信道,上行信道带宽较小,是多对一的共享信道.因此HFC网络的MAC(Medium Access Control)层协议设计重点,在于如何解决共享信道的接入冲突问题,以及如何提高上行信道的利用率和降低上行信道的接入延时.本文结合当前HFC网络中主要MAC层协议的设计思想,从本质上分析了影响协议性能的关键因素.通过对MCNS(The Multimedia Cable Network System)提出的MAC层协议——DOCSISv1.0(Data-Over-Cable Service Interface Specifications version 1.0进行仿真,有力证实了本文的分析结果,对我们进一步深入研究HFC网络接入技术具有很好的指导意义. 相似文献
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该文提出一种新的MAC协议,其目的是增加802.11b的网络容量。虽然IEEE的802.11b协议提供了较高的原始速率,但是物理层和MAC层随速率提高而引入的额外开销也不断增大。此外,物理层规范定义了两种物理层数据单元格式,但是研究者没有研究如何利用开销小的物理层数据单元来提高802.11b的容量。该文提出一种物理层自适应的算法,它能自适应地选择802.11b物理层规范中的两种不同物理层数据单元格式进行传输,并计算相应的网络分配向量。通过NS仿真证明,该协议能够提高网络的性能,如端到端的时延,有效吞吐量和传包率,特别是在高负载,高速率情况下。 相似文献
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Mario Marchese Maurizio Mongelli 《International Journal of Communication Systems》2007,20(9):1059-1079
The paper proposes a bandwidth allocation scheme to be applied at the interface between upper layers (IP, in this paper) and Medium Access Control (MAC) layer over IEEE 802.16 protocol stack. The aim is to optimally tune the resource allocation to match objective QoS (Quality of Service) requirements. Traffic flows characterized by different performance requirements at the IP layer are conveyed to the IEEE 802.16 MAC layer. This process leads to the need for providing the necessary bandwidth at the MAC layer so that the traffic flow can receive the requested QoS. The proposed control algorithm is based on real measures processed by a neural network and it is studied within the framework of optimal bandwidth allocation and Call Admission Control in the presence of statistically heterogeneous flows. Specific implementation details are provided to match the application of the control algorithm by using the existing features of 802.16 request–grant protocol acting at MAC layer. The performance evaluation reported in the paper shows the quick reaction of the bandwidth allocation scheme to traffic variations and the advantage provided in the number of accepted calls. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Abduladhim Ashtaiwi Ahmed Iyanda Sulyman Hossam S. Hassanein 《Wireless Communications and Mobile Computing》2014,14(3):339-354
The demand for higher data rate has spurred the adoption of multiple‐input multiple‐output (MIMO) transmission techniques in IEEE 802.11 products. MIMO techniques provide an additional spatial dimension that can significantly increase the channel capacity. A number of multiuser MIMO system have been proposed, where the multiple antenna at the physical layer are employed for multiuser access, allowing multiple users to share the same bandwidth. As these MIMO physical layer technologies further evolve, the usable bandwidth per application increases; hence, the average service time per application decreases. However, in the IEEE 802.11 distributed coordination function‐based systems, a considerable amount of bandwidth is wasted during the medium access and coordination process. Therefore, as the usable bandwidth is enhanced using MIMO technology, the bandwidth wastage of medium access and coordination becomes a significant performance bottleneck. Hence, there is a fundamental need for bandwidth sharing schemes at the medium access control (MAC) layer where multiple connections can concurrently use the increased bandwidth provided by the physical layer MIMO technologies. In this paper, we propose the MIMO‐aware rate splitting (MRS) MAC protocol and examine its behavior under different scenarios. MRS is a distributed MAC protocol where nodes locally cooperate with one another to share bandwidth via splitting the spatial channels of MIMO systems. Simulation results of MRS protocol are obtained and compared with those of IEEE 802.11n protocol. We show that our proposed MRS scheme can significantly outperform the IEEE 802.11n in medium access delay and throughput. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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一种实时以太网介质访问控制协议的时延性能分析 总被引:7,自引:0,他引:7
本文提出一种新的基于持续竞争的实时以太网介质访问控制协议,该协议能够保证实时信号的发送有确定的最大时延.在新协议下,如果检测到冲突,实时节点并不像普通以太网节点一样停止传输,而是坚持发送竞争信号,利用信道冲突通知非实时节点或者低优先级实时节点停止传输,把信道留给高优先级的实时节点.而且该协议与普通以太网介质访问控制协议兼容,这样实时节点与普通以太网节点能共存于同一网络系统中互相通信.文中详细描述了新型以太网介质访问控制协议,分析了实时信号的发送时延,理论分析和仿真均证明了该协议是可行和有效的. 相似文献
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1 IntroductionMobileadhocnetworksareasetofmobilenodeswhichformandself configurethenetworkwithoutthepre deployedcentraladministrativein frastructure (e.g .thebasestationofWLAN) .Thedemandforadhocnetworkshasbeenbloominginthepastyearsinthecommercialandmilitaryappli cations ,becauseonlyadhocnetworkscanbeappliedinthesituationswherethecentraladministrativein frastructurecan tbe pre installed (e .g .battlefields,disasterrescue)orisnoteconomicaltoinstallbecauseoftemporaryuse (e .g .ameetingintherent… 相似文献
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ATM traffic management in an LMDS wireless access network 总被引:1,自引:0,他引:1
We investigate the capacity of LMDS to support ATM services in the local loop. In particular, we evaluate the performance of a MAC protocol for this system when transporting voice and IP traffic using the VBR and GFR service categories of ATM, respectively. Our results show that the MAC protocol is well suited for voice traffic but in general lacks efficient bandwidth management mechanisms to support the more dynamic bandwidth requirements of IP traffic 相似文献
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Kyeong-Eun Han Won-Hyuk Yang Debasish Datta Young-Chon Kim 《Photonic Network Communications》2008,15(3):191-202
In this article, we examine a candidate architecture for wavelength-division multiplexed passive optical networks (WDM-PONs)
employing multiple stages of arrayed-waveguide gratings (AWGs). The network architecture provides efficient bandwidth utilization
by using WDM for downstream transmission and by combining WDM with time-division multiple access (TDMA) for upstream transmission.
In such WDM-PONs, collisions may occur among upstream data packets transmitted simultaneously from different optical networking
units (ONUs) sharing the same wavelength. The proposed MAC protocol avoids such collisions using a request/permit-based multipoint
control protocol, and employs a dynamic TDMA-based bandwidth allocation scheme for upstream traffic, called minimum-guaranteed
maximum request first (MG-MRF), ensuring a reasonable fairness among the ONUs. The entire MAC protocol is simulated using
OPNET and its performance is evaluated in terms of queuing delay and bandwidth utilization under uniform as well as non-uniform
traffic distributions. The simulation results demonstrate that the proposed bandwidth allocation scheme (MG-MRF) is able to
provide high bandwidth utilization with a moderately low delay in presence of non-uniform traffic demands from ONUs. 相似文献
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介质访问控制协议(Medium Access Control , MAC)是水声通信网络中的一种关键技术。与陆地无线通信系统使用无线电波有所不同,水声通信网络依靠水声进行通信。水声通信网络中的MAC协议设计面临许多挑战面,如:传播延迟大、带宽窄、电池不易更换或充电、节点发射功率受限等。因此,陆地无线通信系统的各MAC协议不能直接应用到水声通信网络。本文提出了一种适用于水声通信网络的MACA(MACA-C)协议,该协议主要将传输数据包和控制包结合使用,在每轮握手的过程中,该协议通过发送列的首数据包和RTS控制包来改善信道利用率。仿真结果也表明MACA-C能够达到较高的和稳定的吞吐量性能,同时在保持低碰撞率的前提下增加信道利用率。 相似文献