红外焦平面器件开窗寻址电路的设计

基于可综合风格的Verilog HDL技术,采取控制单元与数据通道分离的设计结构,对320×256红外焦平面阵列的开窗寻址电路进行RTL级建模,设计了具有对红外焦平面阵列任意开窗寻址功能和读出顺序可上下左右翻转功能的寻址电路。并在Cadence NC Verilog环境下进行编译与仿真,仿真结果表明整个设计能够实现预期寻址功能,满足IRFPA读出多样化的需求。     

光突发交换网络中的闭环竞争解析

为改善光突发交换网络(OBS)的性能,深入探讨了光突发交换网络中的闭环竞争解析,提出了OBS网络中的主动资源预留方案OBS—RED和显式竞争通知方案OBS—ECN。OBS—RED采用随机早期丢弃策略,即根据数据信道拥塞情况,随机早期地丢弃控制分组。OBS—ECN的实现需要OBS—RED的支持。在OBS—ECN中,不是随机丢弃控制分组,而是将这一信息显式地通知边缘节点,边缘节点再作相应的处理。OBS—RED与OBS—ECN的应用,有利于提高网络吞吐量和链路带宽资源利用率,大大减少数据突发的阻塞概率。     

On Poisson contention resolution problem with feedback based onconflict intensity

Communication over a random multiple-access, time-slotted, packet-switched, collision-type, broadcast channel with feedback is considered under a Poisson infinite-user model. The feedback generated by the channel provides some information about the intensity of conflicts. Two conflict-resolution algorithms are discussed for the above channel; they achieve throughputs of 0.334 and 0.369, respectively. The modification technique used to arrive at the second algorithm is emphasized. It is pointed out that the modification technique could be helpful in improving the performance of the conflict-resolution algorithms operating under other types of feedback     

Reservation-based contention resolution mechanism forBatcher-Banyan packet switches

The authors introduce a new method, called ring reservation, to design high-capacity packet switches. Input buffering is used with output port reservations to eliminate packet collisions. They describe a 32×32 prototype packet switch, built as a part of a broadband ISDN prototype, which has a per-port capacity of 30-55 Mbit/s     

Delay analysis of interval-searching contention resolution algorithms

The intelligent design of a random multiple-access communication system involves analyzing the tradeoffs among throughput rate, transmission delay, and stability subject to additional restrictions imposed by distributed processing requirements. Interval-searching contention resolution algorithms have been found to achieve high throughput, and simulations have shown that they also possess short average delay. A general approach to the delay analysis of interval-searching contention resolution is proposed based on solving an integral equation for the distribution of a quantity called the transmission lag. For a certain multibit feedback algorithm, this analytical technique leads to exact determination of the throughput-delay characteristic. For the celebrated "0.487" algorithm, the method yields upper and lower bounds to the curve of expected delay versus throughput that are in close agreement with simulation results.     

CORD: contention resolution by delay lines

The implementation of optical packet-switched networks requires that the problems of resource contention, signalling and local and global synchronization be resolved. A possible optical solution to resource contention is based on the use of switching matrices suitably connected with optical delay lines. Signalling could be dealt with using subcarrier multiplexing of packet headers. Synchronization could take advantage of clock tone multiplexing techniques, digital processing for ultra-fast clock recovery, and new distributed techniques for global packet-slot alignment. To explore the practical feasibility and effectiveness of these key techniques, a consortium was formed among the University of Massachusetts, Stanford University, and GTE Laboratories. The consortium, funded by ARPA, has three main goals: investigating networking issues involved in optical contention resolution (University of Massachusetts), constructing an experimental contention-resolution optical (CRO) device (GTE Laboratories), and building a packet-switched optical network prototype employing a CRO and novel signaling/synchronization techniques (Stanford University). This paper describes the details of the project and provides an overview of the main results obtained so far     

A contention resolution algorithm for input-buffered batcher-banyan networks

A simple algorithm for resolving output contentions in an input-buffered Batcher-banyan network is described. The basic idea in this algorithm is to let the binary nodes of the Batcher network participate in the arbitration process. The proposed algorithm is completely distributed and parallel; thus it scales well to large size switches. Furthermore, our algorithm is fair and requires an overhead that is significantly less than that due to the well-known three-phase algorithm. Two variations of the algorithm are described.     

OBS网络信道分级竞争解决方法研究

通过分析光突发交换网络突发数据包产生竞争的原因和现有的几种解决机制,提出了信道分级竞争解决方法,并对其性能进行仿真研究,得出了不同信道配置下突发数据包丢包率和平均处理时延曲线.结果表明,该方法可以有效的降低数据包丢失率,支持不同的业务需求,是一种实用的方案.     

无线城域网中中心调度的竞争解决方案

针对无线城域网PMP模式下的竞争问题，提出了一种中心调度的竞争解决方案CSCR（centralized scheduling contention resolution）。通过对每一时间帧内活动用户站（subscriber stations）数目的预测，基站（basestation）给所有用户站提供了一个优化的竞争窗口，所有用户站都采用该窗口独立地参与竞争。理论分析和模拟结果表明，与IEEE802．16推荐的基于二进制指数回退BEB（binary exponential backoff）算法的方案相比，CSCR方案不但易于实现，而且能更加有效地利用无线资源，同时减少请求接入延时。     

光突发交换中冲突解决的GHA-TS机制

提出了一种新型的冲突解决机制--GHA-TS(priority-based grouping and hybrid-assembly with tail segment)机制,它采用基于优先级的分组复合封装策略,并根据偏射路由阀值选择尾部分段丢弃或偏射路由策略进行冲突解决.仿真结果表明,GHA-TS机制能够有效降低光突发交换网络的丢包率,尤其是高优先级IP报文的丢失率,较好地支持了光突发交换网络的QoS要求.     

Differentiated contention resolution for QoS in photonic packet-switched networks

Packet contention is a major challenge in photonic packet-switched networks due to the lack of random access buffers in the optical domain. Existing contention resolution approaches such as wavelength conversion and fiber-delay-line buffering may significantly increase the overall system cost and may be difficult to implement. To avoid such issues, this paper proposes a framework for providing label-based differentiated contention resolution by exploiting recirculation buffering and deflection routing. To accommodate more options for differentiation and to avoid the potential problem of forwarding packets in a network indefinitely, two classes of loopless deflection algorithms are provided. An analytical model is also developed to evaluate the packet loss probability and the end-to-end delay for different buffering and deflection routing schemes. The paper also investigates the effectiveness of the control schemes in providing differentiated loss and delay through simulation and analysis. The accuracy of the analytical model is confirmed by simulation.     

一种用于解决OBS网中资源竞争的新机制

综合考虑多种因素,对突发的偏置时间进行改进,提出了一种新的解决资源竞争并能提供服务质量(QoS)保证的机制.结合3种信道调度算法(LRU、FF和PS),对该机制进行了仿真,并与PPJET机制进行了对比,结果表明,在突发丢失方面该机制的性能明显优于后者.     

Parallel contention resolution control for input queueing ATM switches

Input queueing ATM switches requiring fast contentional resolution control have been negatively affected by long turn-around time (TAT) due to the distance between an input port controller and a centralised contention controller. A parallel contention resolution control for input queueing switches is presented. The proposed control allows a TAT of more than one cell slot, resulting in the potential development of a centralised contention controller for an ATM switch with an aggregate capacity of 1 Tbit/s.<>     

高速光交换机竞争解决机制研究

在光分组交换网络中,当同一时刻有两个或两个以上的分组以同一波长从同一端口离开光交换节点时就会出现分组竞争,采用不同的竞争解决方法对光分组交换网络性能会产生巨大影响.在光分组交换中解决竞争主要有光缓存、波长变换、偏射路由三种方式.详细阐述了这三种竞争解决方法的原理、实现方式及特点,并对今后发展趋势做出展望.     

Optical contention resolution and buffering module for ATM networks

A new type of buffering module is introduced, suitable for incorporation into optical switch fabrics handling ATM cells. It comprises 2*2 optical switches and optical delay lines, and is equivalent to two interlinked buffers. Performance is characterised in terms of attenuation, crosstalk and cell loss.<>     

A burst segmentation-deflection routing contention resolution mechanism in OBS networks

One of the key problems to hinder the realization of optical burst switching(OBS) technology in the core networks is the losses due to the contention among the bursts at the core nodes.Burst segmentation is an effective contention resolution technique used to reduce the number of packets lost due to the burst losses.In our work,a burst segmentation-deflection routing contention resolution mechanism in OBS networks is proposed.When the contention occurs,the bursts are segmented according to the lowest packet loss probability of networks firstly,and then the segmented burst is deflected on the optimum routing.An analytical model is proposed to evaluate the contention resolution mechanism.Simulation results show that high-priority bursts have significantly lower packet loss probability and transmission delay than the low-priority.And the performance of the burst lengths,in which the number of segments per burst distributes geometrically,is more effective than that of the deterministically distributed burst lengths.     

A review of contention resolution algorithms for IEEE 802.14 networks

Bidirectional Cable TV networks using hybrid fiber coaxial (HFC) systems are good examples of broadcast environments where a contention resolution algorithm is needed in order to allocate the multiaccess medium (in this case the upstream link) among the various nodes. Recent activities of the IEEE 802.14 Working Group aimed at defining the physical and medium access control (MAC) layer protocols for HFC cable networks have focused on the study and evaluation of several contention resolution solutions for inclusion in the MAC protocol specifications. In this article several contention resolution algorithms considered by the IEEE 802.14 group are reviewed. Different implementations for several well known contention resolution algorithms such as tree-based and p-persistence are presented. Their performance is evaluated in the HFC context with respect to upstream channel allocation, roundtrip delay, various traffic types, and number of stations in the network. Simulation results for configurations and scenarios of interest are also presented.     

解决光突发交换竞争的新模型

针对光突发中的竞争问题，提出了一种分割反馈模型，相应地建立了数学分析模型，并进行了仿真与性能分析。结果表明这一模型是解决光突发交换中竞争问题的一个较佳方案。     

An optical packet contention resolution supporting QoS differentiation with LRWC wavelength converters for OPS

The wavelength conversion is regarded as an effective way to resolve the optical packet contention in the wavelength domain for optical packet switching. An optical packet switching node, based on shared-per-node equipped with limited range wavelength converters and parametric wavelength converters (SPN-LP), is designed to further reduce optical packet loss probability. A novel optical packet contention resolution with priority differentiation wavelength scheduling algorithm to support quality of service (QoS) for the SPN-LP architecture is put forward in the article. The simulation results show that proposed optical packet resolution enables a good QoS differentiation, namely the high priority contending optical packet has the sufficient low packet loss probability.     

End-to-end contention resolution schemes for an optical packet switching network with enhanced edge routers

This paper investigates contention resolution schemes for optical packet switching networks from an end-to-end perspective, where the combined exploitation of both core routers and edge routers are highlighted. For the optical-core network, we present the architecture of an optical router to achieve contention resolution in wavelength, time, and space domains. Complementing the solution involving only the core router intelligences, we propose performance enhancement schemes at the network edge, including a traffic-shaping function at the ingress edge and a proper dimensioning of the drop port number at the egress edge. Both schemes prove effective in reducing networkwide packet-loss rates. In particular, scalability performance simulations demonstrate that a considerably low packet-loss rate (0.0001% at load 0.6) is achieved in a 16-wavelength network by incorporating the performance enhancement schemes at the edge with the contention resolution schemes in the core. Further, we develop an field-programmable gate-array (FPGA)-based switch controller and integrate it with enabling optical devices to demonstrate the packet-by-packet contention resolution. Proof-of-principle experiments involving the prototype core router achieve an error-free low-latency contention resolution.