Contention-based reservation protocol in fibre optic local area network with passive star topology

A contention-based reservation protocol using a separate control channel for a fibre optic local area network (LAN) with a passive star topology and WDM technology is proposed. Its delay-throughput characteristic is investigated.<>     

Slotted Aloha and reservation Aloha protocols for very high-speedoptical fiber local area networks using passive star topology

A number of cases of slotted Aloha protocols for high-speed optical fiber local area networks (LANs) are presented and analyzed. The results are compared to the cases of Slotted Aloha/Aloha schemes presented by I.M.I. Habab et al., (1987) and N. Mehravori (1990). The proposed schemes were found to offer better throughput and delay characteristics. These cases are also compared with Aloha/N-server and CSMA/N-server protocols presented by Habab and Mehravori. Some of the considered protocols offer better throughput when the data packet lengths are small. Two cases of reservation Aloha protocols are presented and analyzed     

Random access protocols for high-speed interprocessor communicationbased on an optical passive star topology

A multiple-instruction multiple-data (MIMD) distributed memory parallel computer system environment is considered. Media access control protocols that maintain good performance with high capacity optical channels are investigated. Three examples of star-coupled structures are introduced, one of which exhibits optical self-routing. Self-routing single-step optically interconnected communication structures can be designed through the incorporation of agile laser diode sources and wavelength tunable optical filters in a wavelength-division multiple-access environment. Intermediary latencies typical of MIMD distributed memory systems are eliminated. The degree and diameter of the resulting structures are dramatically reduced, and the complexity of the communication subsystem is reduced since intermediate buffering and routing of packets are eliminated     

Contention-based MAC protocols with erasure coding for wireless data networks

Contention-based medium access control (MAC) protocol is a key component for the success of wireless data networks. Conventional random access protocols like ALOHA and Carrier Sense Multiple Access (CSMA) suffer from packet collision which leads to low throughput. Aimed at improving the throughput performance, we propose to integrate erasure coding with contention-based MAC protocols for recovering collided packets. To demonstrate the effectiveness of this approach, we focus on combining erasure coding with slotted ALOHA and slotted non-persistent CSMA in this paper. The performances of the resulting protocols are evaluated by both analytical model and simulation. Simulation results match very well with analytical results and show that the system throughput is increased for low to medium traffic loading. Packet loss ratio is also improved considerably with our scheme when the maximum number of packet retransmission times is limited. However, the delay for our scheme is higher due to the longer waiting time in our scheme for recovering collided packets. It is also shown that delay can be significantly reduced if we choose appropriate coding parameters though throughput will be sacrificed.     

Protocols for multichannel optical fibre LAN using passive star topology

Multiple access protocols for a multichannel optical fibre LAN using a passive star topology are discussed. Of the available channels one is used to transmit control packets and the remaining channels are used to transmit data packets. The protocols use the slotted Aloha for the transmission of control packets which identify their intended receiver address. They work independently of the propagation time of the network and achieve higher throughput than comparable protocols proposed in the literature.<>     

Protocols for very high-speed optical fiber local area networks using a passive star topology

This paper deals with the problem of interconnection of many high-speed bursty traffic users via an optical passive star coupler. Each user can tune its laser over a range of wavelengths, thus resulting in a wavelength division multiplexed communication. The total number of wavelengths over which user tunability exists could be much smaller than the number of users. Therefore, some form of random access sharing and packet switching may be necessary. We propose several protocols that require each user to have a tunable receiver. The information on "where" and "when" to tune the laser is confined to a control (setup) channel that users tune to when in idle mode. An interconnection between two users lasting for the length of a data packet is set up on the control channel by the transmitting user who informs the receiving user where to tune in order to receive the data packet. No centralized control or coordination is required among the users. After analyzing each protocol, we present the throughput/ delay versus the offered traffic and the delay versus throughput in a sequence of plots. We show that in typical applications an average throughput of up to 0.95 can be achieved at a reasonable average delay using one of these protocols. In our benchmark examples we present an optical local area network (LAN) with a total throughput of 100- Gbit/s in which every user has access to a 1-Gbit/s data rate and the network can support over 1000 users. The protocols can be used in a) large LAN's that do not require a large capacity, b) small LAN's (1 kin) that require a large capacity and c) large LAN's (tens of kilometers) that require a rather large capacity.     

Performance evaluation with receiver collisions analysis in veryhigh-speed optical fiber local area networks using passive star topology

The problem of receiver collisions in high-speed optical fiber local area networks is studied in this paper. The configuration of high-speed multichannel LAN's with wavelength division multiplexing techniques using an optical fiber bandwidth gives rise to receiver collisions phenomena. We give a detailed analysis and develop rigorous methods to examine the effect of receiver collisions in this type of multiaccess environment. The evaluations are carried out assuming Poisson arrivals and finite population and examine the throughput performance and the rejection probability at destination. Also numerical results are showing the throughput performance behavior as it compared with the protocol case without receiver collisions     

Traffic analysis of a local area network with a star topology

Two forms of fast circuit switching are modeled and studied through mathematical analysis and Monte Carlo simulation. The two examples described use the switching technique in an optical-fiber-based local area network with a star topology. The technique is compatible with time-division multiplexing techniques that are used for a range of traffic classes. Further, the technique trades transmission capacity for processing power, which is the critical limitation of the system. By means of a certain independence assumption, the first form of fast circuit switching is modeled as an M/G/1 queue. The results of the analysis show excellent agreement with simulation. The general result is that there is good system throughput, despite simplicity of processing. The second form, in which rather than first-come first-served the discipline is to search for a message whose destination queue is free, is studied by means of simulation alone. The results indicate an improved performance with a modest increase in processing power     

Performance and protocol improvements for very high speed opticalfiber local area networks using a passive star topology

Two random-access schemes for a multiuser very-high-speed optical data network based on a star topology are presented and analyzed. The protocols presented do not require any type of carrier sensing, and their performance is independent of a, the normalized propagation time of packets over the optical medium. This property is rather important when dealing with very-high-speed networks which result in high values of a, because the performance of the conventional carrier sensing schemes is poor under such conditions. The protocols outperform the corresponding algorithms of I.M.I. Habbab et al. (1987) for all values of system parameters     

Performance evaluation of an IEEE 802.15.4 sensor network with a star topology

One class of applications envisaged for the IEEE 802.15.4 LR-WPAN (low data rate—wireless personal area network) standard is wireless sensor networks for monitoring and control applications. In this paper we provide an analytical performance model for a network in which the sensors are at the tips of a star topology, and the sensors need to transmit their measurements to the hub node so that certain objectives for packet delay and packet discard are met. We first carry out a saturation throughput analysis of the system; i.e., it is assumed that each sensor has an infinite backlog of packets and the throughput of the system is sought. After a careful analysis of the CSMA/CA MAC that is employed in the standard, and after making a certain decoupling approximation, we identify an embedded Markov renewal process, whose analysis yields a fixed point equation, from whose solution the saturation throughput can be calculated. We validate our model against ns2 simulations (using an IEEE 802.15.4 module developed by Zheng [14]). We find that with the default back-off parameters the saturation throughput decreases sharply with increasing number of nodes. We use our analytical model to study the problem and we propose alternative back-off parameters that prevent the drop in throughput. We then show how the saturation analysis can be used to obtain an analytical model for the finite arrival rate case. This finite load model captures very well the qualitative behavior of the system, and also provides a good approximation to the packet discard probability, and the throughput. For the default parameters, the finite load throughput is found to first increase and then decrease with increasing load. We find that for typical performance objectives (mean delay and packet discard) the packet discard probability would constrain the system capacity. Finally, we show how to derive a node lifetime analysis using various rates and probabilities obtained from our performance analysis model.

Secure data communication protocols in bidirectional star network

The author describes a secure data communication method based on the CSMA/CD protocol in bidirectional star networks. A procedure for detecting packet collision while transmitting the jamming signal is required. The author assess two kinds of protocol, a CRV (code rule violation) protocol and a DR (delayed replying) protocol     

Wavelength accuracy and output power of multiwavelength DFB laser arrays with integrated star couplers and optical amplifiers

In this letter, we report the static performance of multiwavelength DFB laser arrays with integrated star couplers and optical amplifiers built for the reconfigurable optical network testbed. By the use of wavelength redundancy and proximity effect, wavelength deviations of /spl plusmn/0.2 nm or less from the designated eight-wavelength comb have been achieved with high yield. Simultaneous operation of eight wavelengths has also been demonstrated. In spite of the inherent splitting loss of 13 dB, high output powers of about -13 dBm and 0 dBm per wavelength have been measured into a single-mode fiber without and with on-chip optical amplification, respectively.     

Buffer analysis with finite number of tunable receivers in WDM passive star networks

This study develops a performance model as an expansion of the receiver collision analysis presented in [I.E. Pountourakis, Performance evaluation with receiver collisions analysis in very high-speed optical fiber local area networks using passive star topology, J. Lightwave Technol. 16 (12) (1998) 2303–2310] for WDM networks. By theoretical analysis we estimate the receiver collision phenomenon and evaluate the performance measures and the rejection probability at destination for finite number of tunable receivers. Receiver collision analysis makes the performance behavior more realistic and expands the original analysis.     

An active star topology for improving fault confinement in CAN networks

The controller area network (CAN) is a field bus that is nowadays widespread in distributed embedded systems due to its electrical robustness, low price, and deterministic access delay. However, its use in safety-critical applications has been controversial due to dependability limitations, such as those arising from its bus topology. In particular, in a CAN bus, there are multiple components such that if any of them is faulty, a general failure of the communication system may happen. In this paper, we propose a design for an active star topology called CANcentrate. Our design solves the limitations indicated above by means of an active hub, which prevents error propagation from any of its ports to the others. Due to the specific characteristics of this hub, CANcentrate is fully compatible with existing CAN controllers. This paper compares bus and star topologies, analyzes related work, describes the CANcentrate basics, paying special attention to the mechanisms used for detecting faulty ports, and finally describes the implementation and test of a CANcentrate prototype.     

Partitioned optical passive star (POPS) multiprocessorinterconnection networks with distributed control

This paper presents a partitioned optical passive star (POPS) interconnection topology and a control methodology that, together, provide the high throughput and low latency required for tightly coupled multiprocessor interconnection applications. The POPS topology has constant and symmetric optical coupler fanout and only one coupler between any two nodes of the network. Distributed control is based on the state sequence routing paradigm which multiplexes the network between a small set of control states and defines control operations to be transformations of those states. These networks have highly scalable characteristics for optical power budget, resource count, and message latency. Optical power is uniformly distributed and the size of the system is not directly limited by the power budget. Resource complexity grows as O(n) for the couplers, O(n√n) for transceivers, and O[√nlog(n)] for control. We present analysis and simulation studies which demonstrate the ability of a POPS network to support large scale parallel processing (1024 nodes) using current device and coupler technology     

基于星型拓扑结构的全台数字通话系统

2016年,贵州广播电视台完成了二期大楼全新播总控系统的建设.在新系统的设计中,采用了ClearCom公司基于Eclipse HX通话矩阵为中心、有线+无线互通方式的全台数字通话系统.通话系统为节目制作、演播室直播、电视播出传输、节目编排等环节的快速沟通提供了稳定、高效、便捷的功能性平台.通话网络基于星型拓扑结构模型的C/S架构方式,具有很高的可靠性和稳定性.通话系统作为电视台全台通话联络的技术保障系统,操作方便快捷,应用效果良好.通话系统是电视台必不可少的子系统,本文就全台数字通话系统的设计应用方面做详细介绍.     

Optical cascade star network--A new configuration for a passive distribution system with optical collision detection capability

A new fiber-optic passive network configuration with novel star couplers is reported. The new optical network configuration, an Optical Cascade Star Network, optimizes contradictory requirements for network system size and cable cost, and matches the actual layout in offices or factories. The star coupler is novel in that the optical signal does not return to the source terminals. This feature enables cascade connection of star networks, the use of simple repeaters for system extension, and the easy support of carrier sense multiple access with collision detection (CSMA/CD) bus access procedure. Experimental results obtained from novel star couplers, optical transceivers with (CSMA/CD) bus compatibility, and a total network system are also discussed.     

Self-protected time-division-multiplexed passive access networks in tree and ring topology architectures

In this investigation we propose and experimentally demonstrate the self-protected and survivable time-division-multiplexed passive optical networks (PONs) in tree and ring topology architectures against fiber fault. Here, the feasible protection access architectures for the tree- and ring-based PONs are studied and discussed. Furthermore, different scenarios of fault locations, such as in the feeder fiber and distribution fiber, are also studied in the optical distributed networks.     

Performance analysis of a star topology of interconnected networksunder 2nd-order Markov network output processes

The concept of approximating the output process of slotted multiuser random-access communication networks (i.e. the process of the successfully transmitted packets within the networks) by a second-order Markov process is introduced. A method is developed for analytically calculating the parameters of the approximating process for a class of random-access algorithms. The method is illustrated by considering a specific random-access algorithm from that class. The mean time that a packet spends in the central node of a star topology of interconnected networks is incorporated in the evaluation of the accuracy of the proposed approximation. This quantity is calculated under the proposed approximation on the output processes of the interconnected networks and is compared to simulation results from the actual system. Results showing the accuracy of the proposed approximation for networks operating under a specific random-access algorithm are presented     

Tunable multiwavelength Brillouin-erbium fiber laser with a polarization-maintaining fiber Sagnac loop filter

We demonstrate the generation of 12-wavelength comb with 14.5-nm tunable range in the Brillouin-Erbium fiber laser. This is achieved through tuning the gain profile of Erbium-doped fiber by a Sagnac loop filter with 18-cm polarization-maintaining fiber, in conjunction with modifying the wavelength of Brillouin pump. The experiment also demonstrates that the tunable range is closely equal to the 3-dB bandwidth of Sagnac loop filter due to its periodic transmission profile. Meanwhile, the effect of the 980-nm pump on the tunable multiwavelength generation is investigated. The power of 980-nm pump has a great effect on the wavelength number and the output power of the generated multiwavelength comb, but little on the tunable range. This technique may be applicable to multiwavelength operation lasers with a large tunable range.