A broadband optoelectronic packet switching system

A novel architecture is presented for a optoelectronic hybrid packet-switching system (HYPASS) for the distribution of multiple-bit-rate broadband services. HYPASS is based on an input-buffered/output-controlled arbitration protocol. This packet switch uses novel multiwave-length optical networks to accomplish routing and transmission of the packets. This system is specifically adapted to utilize the strengths of both optical and electronic technologies     

PROTON: a media access control protocol for optical networks withstar topology

A new multiple access protocol called PROTON (PROTocol for Optical Networks) is developed for optical local area networks based on a passive star topology. PROTON uses wavelength division multiplexing (WDM) and is highly bandwidth-efficient. One of the available wavelengths is used as a control channel. Time is divided into fixed-sized slots. The size of the slots is the same for the control and the data channels. Before transmitting a packet, a station must compete with others for a slot in a data wavelength, using a collision-free procedure. Transmitting stations and the corresponding wavelengths for their data transmissions are determined at each station by a simple arbitration scheme. The protocol is suitable for networks where the number of users can be much larger than the number of available data channels. In addition to propagation delays, it is considered that transmitter and receiver tuning times as well as the times required to process control packets are not negligible. Whenever possible, and to maximize the throughput of the network, tuning and processing times of transmitters and receivers are overlapped with each other and with data transmission times. Also, data slot requests and packet transmissions are scheduled in a pipeline fashion, thus reducing the detrimental effects on throughput and packet delay of long propagation delays. The paper includes an analysis of the maximum throughput characteristics of PROTON. An analytical model is developed, and several performance measures are obtained     

Multiwavelength networks and new approaches to packet switching

The author shows how the bandwidth available through the use of multiwavelength optical-fiber technology can be used to achieve novel large-capacity switching systems to address anticipated switching bottlenecks. He does so by describing the features and network applications of a specific multiwavelength network, the Bellcore LAMBDANET packet switch. The discussion is then extended to a number of recent proposals for switching fabrics based on this new multiwavelength technology. The particular technologies he discusses are: the photonic knockout switch, a proposal similar to the concept of the LAMBDANET, but not requiring N receivers at each node; the FOX (fast optical cross-connect), an active wavelength routing approach; the ShuffleNet architecture; the HYPASS and BHYPASS switches; the coherent wavelength division λ switch; and the Bellcore Star-Track multicast switch     

Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance analysis of an optical CDMA MAC protocol with variable-size sliding window

A media access control protocol for optical code-division multiple-access packet networks with variable length data traffic is proposed. This protocol exhibits a sliding window with variable size. A model for interference-level fluctuation and an accurate analysis for channel usage are presented. Both multiple-access interference (MAI) and photodetector's shot noise are considered. Both chip-level and correlation receivers are adopted. The system performance is evaluated using a traditional average system throughput and average delay. Finally, in order to enhance the overall performance, error control codes (ECCs) are applied. The results indicate that the performance can be enhanced to reach its peak using the ECC with an optimum number of correctable errors. Furthermore, chip-level receivers are shown to give much higher performance than that of correlation receivers. Also, it has been shown that MAI is the main source of signal degradation.     

采用动态波长分插复用器的光突发交换环网中的控制协议研究

提出了一种光突发交换(OBS)环网控制协议——延迟光突发固定周期(DBFP)协议。它采用动态波长分插复用器(WADM)。即采用波长可调发送可调接收(TTTR)机制．通过提前的光突发控制分组(BCP)．为光突发数据分组(BDP)预留资源，并利用固定长度的光纤延迟线(FDL)将突发数据包延迟同定的时间，以便等待所有已经预留的突发数据包发送完毕，从而完全避免突发数据包冲突问题。仿真结果表明。延迟光突发固定周期协议能完全避免突发数据包冲突。同时有效地实现了波长统计复用、按需分配和空间重用，波长重用效率高达160％。从而提高链路利用率．特别适合于突发性的业务；并且延迟光突发固定周期协议所引入的时延为1ms左右．对业务的影响不大。     

Design and Performance Evaluation of a Separated Control Signaling Protocol for WDM Optical Networks

In WDM optical networks, an efficient control signaling protocol is required to dynamically establish lightpaths. This paper proposes a separated control signaling protocol (SCSP) and compares the performance of SCSP with a conventional integrated control signaling protocol (ICSP). The conventional ICSP makes reservations sequentially from the source to the destination for setting up and tearing down lightpaths. It increases the control overhead and wastes the network resource if it cannot reserve the network resource at an intermediate node. Specifically, if the receiver at the destination is not available after successful reservation at intermediate nodes, it wastes a lot of bandwidth. It causes decreasing chances of reservation for other lightpaths. Instead, SCSP separates bearer control from call control to reduce the waste of network resources. The call control function checks the availability of network resources such as wavelengths and receivers. Bearer control reserves, allocates, and releases network resources. To evaluate the performance of the two protocols, they are mathematically analyzed using a probabilistic model. Simulation results are also provided to compare the proposed protocol with the conventional ICSP in terms of utilization and blocking probability. From the results of simulation and iterative analysis, we can observe that SCSP performs better than ICSP.     

A Weighted Scheduling Mechanism to Reduce Multicast Packet Loss in IPTV Service over EPON

This letter proposes a weighted scheduling mechanism for Internet protocol television (IPTV) to improve the loss performance of multicast transmission over an Ethernet passive optical network (EPON). We propose a new weight policy from the number of multicast receivers to proportionally allocate the downstream bandwidth of IPTV traffic. The proposed mechanism is used in an optical line terminal to decrease lost packets of favorite IPTV services because the lost multicast packets are proportional to the number of receivers. The total proportion of lost multicast packets is reduced by up to 73% in an EPON.     

A media-access protocol for packet-switched wavelength divisionmultiaccess metropolitan area networks

A dynamic time-wavelength division multiaccess protocol (DT-WDMA) is proposed for metropolitan-sized multichannel optical networks employing fixed wavelength transmitters and tunable optical receivers. Control information is sent over a dedicated signaling channel and data are sent over channels owned by the transmitters. Time is divided into slots on each channel and slots on the control channel are further split into mini-slots. Fixed time-division multiaccess (TDM) is used within each slot on the control channel. Transmitters indicate their intention to transmit a packet by transmitting the destination address during their appropriate mini-slot in the control channel and then transmit their packet in the next slot on their data channel. Receivers listen to the control channel and tune to the appropriate channel to receive packets addressed to them. A common but distributed arbitration algorithm is used to resolve conflicts when packets from many transmitters contend for the same receiver. Each receiver executes the same deterministic algorithm to choose one of the contending packets. Each transmitter uses the same algorithm to determine the success or failure of its packet     

Synchronous Wavelength Reusing/Sharing Protocols for Nonregenerative WDM Dual Buses

The dual-bus optical network with nonregenerative stations has become popular. In general, the nonregenerative station implementation is better than the regenerative station implementation in media access control delay, cost, and susceptibility of station failures, etc. In this paper, two novel cycle-based protocols, named as synchronous wavelength sharing protocol (SWSP) and synchronous wavelength reusing/sharing protocol (SWRP), are proposed for nonregenerative wavelength-division-multiplexing dual-bus networks. The simulation results show that the network throughput and delay of SWRP are better than those of SWSP, when the numbers of wavelengths and tunable receivers are both limited, and/or the network traffic load is heavy.     

Optical CDMA random access protocols with and without pretransmission coordination

The link layer of an optical direct-detection code-division multiple-access (CDMA) packet network is considered. Two different protocols that need pretransmission coordination are proposed. A variation of the second protocol that does not need pretransmission coordination is discussed. Both system throughput and average packet delay are derived and investigated for two different receiver models: the correlation and chip-level receivers. Both multiple-access interference and the photodetector's shot noise are taken into account in the analysis. The case where the number of users exceeds the available number of CDMA codes is numerically investigated. Our results reveal that the proposed protocols yield competitive system throughputs when used with the correlation receivers. Further, significant improvement in the throughput is achieved when using chip-level receivers along with the second protocol.     

Design and implementation of the optical fiber control and transmission module in multi-channel broadband digital receiver

An optical fiber control and transmission module is designed and realized based on Virtex-7 field programmable gata array （FPGA）, which can be applied in multi-channel broadband digital receivers. The module consists of sampling data transfer submodule and multi-channel synchronous sampling control submodule. The sampling data transmission in 4× fiber link channel is realized with the self-defined transfer protocol. The measured maximum data rate is 4.97 Gbyte/s. By connecting coherent clocks to the transmitter and receiver endpoints and using the self-defined transfer protocol, multi-channel sampling control signals transferred in optical fibers can be received synchronously by each analog-to-digital converter （ADC） with high accuracy and strong anti-interference ability. The module designed in this paper has certain reference value in increasing the transmission bandwidth and the synchronous sampling accuracy of multi-channel broadband digital receivers.     

An Arrangement of Channels and Transceivers in Optical Packet Switching Networks

Based on a media access and control（MAC）protocol,an arrangement of channels and transceivers in optical packet switching dense wavelength division multiplexing（DWDM）networks is proposed in this paper.In order to reduce the cost of nodes,fixed transmitters and receivers are used instead of tunable transmitters and receivers.Two fixed transmitters and many fixed receivers are used in each node in the scheme.The average waiting delay of this scheme is analyzed through mathematics and computer simulation.The result shows that the property of the scheme is almost the same as using tunable transmitter and receiver.Furthermore,if the tuning time of tunable transmitters is taken into account,the performance of the tunable transmitter scheme is poor than this scheme at the average waiting delay and throughput of the network.     

Microwave-bandwidth optical receiver systems

A theoretical and experimental evaluation of optical communications systems capable of microwave bandwidths is presented. The optical transmitter, modulator, and detection techniques are discussed with respect to both direct-detection and optical heterodyne receivers, and experiments in a nonlaboratory environment are described. At the high optical power levels or photon rates which are fundamentally necessary for gigahertz instantaneous bandwidths, it is found that signal-shot-noise limited operation may be obtained with new wideband photodetectors incorporating internal gain. Direct-detection receivers are thus generally superior to heterodyne receivers in these systems. A comparison is made of the relative merits of alternative systems and their dependence on various parameters such as information capacity, range, and background illumination.     

Design and Analysis of a Synchronous Transmission WDMA Protocol

In this paper, we propose a synchronous WDMA protocol for a passive star topology and suggest a new architecture for the network interface of each station. The multichannel nature of WDM networks involves receiver collision phenomena at the destination. We develop an analytical model based on a finite number of tunable receivers and a finite number of stations to investigate the performance of the proposed protocol. Numerical results are showing the performance behaviour for various number of channels, stations, and tunable receivers. Also simulation results are presented for comparison with the results obtained by the performance analysis.     

Frequency division multiplexed optical networks using heterodynedetection

The optical heterodyne process is described. Because the best attainable system gain (transmitter power divided by receiver sensitivity) is only about 50 dB for lightwave systems, as compared with values approaching 100 dB at radio frequencies, it is extremely important in building an optical network (such as a local area network, or LAN) to minimize excess tap losses. It is shown that a star coupler provides a nearly ideal means for interconnecting a multiterminal network. Three areas in which problems unique to optical systems have been discovered are discussed. Theses are transmitters for coherent optical systems, optical frequency determination and control, and polarization control and optical receivers. Experimental progress is briefly discussed     

A multistage hierarchical distributed arbitration technique for priority-based real-time communication systems

ISO 11898 is a communication protocol based on the carrier sense multiple access with collision detection and arbitration on message priority (CSMA/CD+AMP) technique, which at present is largely used as a real-time network for industrial environments. Unfortunately, because of the peculiarities of the arbitration technique it adopts, it suffers from severe limitations on the maximum extension of the network, which cannot be overcome simply by means of improvements in the transceiver's technology as they depend on the limited propagation speed of the signals on the communication support. In this paper, a new kind of network is presented that features a behavior very similar to ISO 11898, but which achieves noticeably larger areas to be covered without having to reduce the bit rate. It relies on a tree topology and adopts a brand new multistage hierarchical distributed arbitration technique, which takes the increased propagation delays into account properly.     

SUCCESS: a next-generation hybrid WDM/TDM optical access network architecture

In this paper, the authors propose a next-generation hybrid WDM/TDM optical access network architecture called Stanford University aCCESS or SUCCESS. This architecture provides practical migration steps from current-generation time-division multiplexing (TDM)-passive optical network (PONs) to future WDM optical access networks. The architecture is backward compatible for users on existing TDM-PONs, while simultaneously capable of providing upgraded high-bandwidth services to new users on DWDM-PONs through advanced WDM techniques. The SUCCESS architecture is based on a collector ring and several distribution stars connecting the CO and the users. A semipassive configuration of the Remote Nodes (RNs) enables protection and restoration, making the network resilient to power failures. A novel design of the OLT and DWDM-PON ONUs minimizes the system cost considerably: 1) tunable lasers and receivers at the OLT are shared by all ONUs on the network to reduce the transceiver count and 2) the fast tunable lasers not only generate downstream data traffic but also provide DWDM-PON ONUs with optical CW bursts for their upstream data transmission. Results from an experimental system testbed support the feasibility of the proposed SUCCESS architecture. Also, simulation results of the first SUCCESS DWDM-PON MAC protocol verify that it can efficiently provide bidirectional transmission between the OLT and ONUs over multiple wavelengths with a small number of tunable transmitters and receivers.     

Integrating Security in the MAC Layer of WDM Optical Networks*

We introduce a new technique for providing security in a broadcast-and-select, wavelength-division-multiplexed (WDM) optical network. The approach provides privacy of communications by employing a novel challenge-response scheme and exploiting the tuning delay inherent in optical receivers. The proposed technique can be integrated easily into any existing WDM media-access-control (MAC) protocol that employs tunable receivers. The modified protocol would require every idle user, who is not scheduled to receive data, to tune in to a channel that does not contain sensitive data. A violation of the protocol can be detected with very high probability, and appropriate measures can be taken against the violator. The technique provides features that cannot be achieved with cryptography alone. Significant benefits of the proposed approach include the ability to detect security violations as they occur, and an efficient mechanism to provide privacy for multicast transmissions. We develop two simple solutions to deal with different levels of attack: (1) eavesdroppers working alone, and (2) eavesdroppers working in collaboration. We also introduce a dynamic channel allocation scheme that can further reduce the number of required overhead channels, with minimal loss in the capability to detect eavesdropping violations.     

Fair MAC protocol for optical ring network of wavelength-shared access nodes

In this paper, a WDM optical ring consisting of access nodes with fixed transmitter-n fixed receivers (FT—FR ⁿ ) is considered. As access nodes share a wavelength channel there is trade-off between node throughput and fairness among them. In order to abbreviate the transmission unfairness and to increase the throughput, we propose p-persistent medium access control (MAC) protocol. Each node uses the carrier sense multiple access with collision avoidance (CSMA/CA) protocol to transmit packets, and decides whether to use a local empty slot with probability p when a transferred packet based on source-stripping is dropped and emptied. Numerical prediction for the proposed MAC protocol is introduced to compute the maximum node throughput under uniform traffic condition. For more detail results, we use network simulation with self-similar traffic and introduce various results. The proposed MAC protocol gives better node throughput than non-persistent protocol and shows an improved fairness factor than 1-persistent protocol. Through simulation, we also find the reasonable probability of p-persistent protocol for a given architecture.