Fixed-wavelength Receiver Research Articles

Capacity enhancement in packet switched slotted ring wavelength division multiplexed transport networks

In this paper, all-optical WDM networks based on a slotted multichannel ring topology have been investigated. The nodes are equipped with one fixed-wavelength receiver, wavelength-tunable transmitter and provide packet-mode transport in WDM network. The topology provides one logical channel to be associated with each destination node. Each channel is shared in statistical time division by all nodes transmitting to a given destination. The capacity enhancement has been demonstrated by comparing all optical WDM network by increasing the number of nodes. It is concluded that by increasing the number of nodes in the topology, the token queue length capacity, the token arrival rate are increased and the token arrival period is decreased which results in overall increase in the performance and capacity of the logical WDM network.

Wavelength assignment to minimize requirement on tunable range of optical transceivers in WDM networks

In this paper we consider WDM networks with a tunable transmitter and a fixed-wavelength receiver at each station (similar results hold when the transmitter is fixed and the receiver is tunable). Traditionally, each station is required to be able to access all wavelength channels used in the network. Such requirement limits the number of wavelengths that can be exploited in a WDM network up to the size of the resolvable wavelength set of optical transceivers, which is very limited with current technology. In this paper we observe that this requirement is actually an overkill. To realize a communication topology, physical or logical, it is sufficient that the tunable range of the transmitter at each station covers all the wavelengths of the receivers at its neighboring stations. This observation leads to the study of optimal wavelength assignment to minimize the tunability requirement while still guaranteeing that each receiver has a unique wavelength channel. This optimization problem is shown to NP-complete in general and approximation algorithms with provable performance guarantees are presented. When the communication topologies are complete graphs, de Bruijin digraphs, Kautz digraphs, shuffle or rings, the optimal solutions are provided. Finally, we present tight lower bounds when the communication topology is a hypercube.

Multihop packet scheduling in WDM/TDM networks with nonnegligible transceiver tuning times

This paper addresses the design of packet transmission schedules in photonic slotted wavelength-division multiplexing/time-division multiplexing broadcast-and-select networks with W wavelengths and N nodes. Nodes are equipped with one tunable-wavelength transmitter with nonnegligible tuning times and one fixed-wavelength receiver. A new scheduling algorithm that exploits multihop packet transfer to shorten the duration of scheduling periods is first proposed. A single-hop scheduling algorithm that performs slightly better than previous proposals is then described. A simulation-based analysis of the two algorithms shows that they jointly lead to significant improvements in both throughput and delay with respect to previous single-hop schedules.

All-optical WDM multi-rings with differentiated QoS

This article considers all-optical WDM networks based on a slotted multichannel ring topology, where nodes are equipped with one fixed-wavelength receiver and one wavelength-tunable transmitter; and shows how to design very effective MAC protocols that provide packet-mode transport to multiple information flows with different QoS requirements. As an example, we describe SR3, a collision-free slotted MAC protocol which combines a packet scheduling strategy (called SRR), a fairness control algorithm (called MMR); and a reservation mechanism. SRR achieves an efficient exploitation of the available bandwidth, MMR guarantees fair throughput access to each node, and SR3, by permitting slot reservations, leads to tighter control on access delays, and can thus effectively support traffic classes with different QoS requirements.

Daisy: a scalable all-optical packet network with multifiber ring topology

This paper presents Daisy, a scalable all-optical packet network where each node is equipped with one wavelength-tunable transmitter and one fixed-wavelength receiver. Network scalability is obtained with a novel multifiber ring topology that allows spatial reuse of wavelengths and requires an optical transmitted power proportional typically to the square root of the number of nodes. The scalability of the proposed topology is analytically evaluated by taking into account the characteristics of state-of-the-art optical components. The topology of Daisy provides one logical channel per destination node. Each channel is shared in statistical time division by all nodes transmitting to a given destination. A channel inspection capability at each node allows the implementation of efficient slotted ordered access protocols. As an example, a simple and efficient protocol named SRR (Synchronous Round Robin) is described, and its performance is assessed by means of simulation.

Topological embedding into WDM optical passive star networks with tunable transmitters of limited tuning range

Wavelength Division Multiplexing (WDM) has been widely used for studying the performance of optical networks, especially those employing optical passive star couplers. Many models have been proposed for WDM on an optical passive star coupler, such as each station equipped with a single tunable transmitter and a single fixed wavelength receiver, and each station with multiple tunable transmitters and multiple tunable receivers. The current technology only allows the transceivers to be tunable in a small range, a fact ignored in previous studies. In this paper, we focus on the design of WDM optical passive star networks with tunable transmitters of limited tuning range and fixed wavelength receivers. The limited tuning range has effects on the maximum delay, the total number of wavelengths which can be used, and the topological embedding. Complete graphs, meshes, and hypercubes are the three topologies studied in this paper. The relationship between the total number of wavelengths which can be utilized and the embedded topology is established. The bound for the maximum delay is analyzed. The optimal embedding algorithms are given for the systems embedded with one of the three topologies.

TDM and TWDM de Bruijn networks and ShuffleNets for optical communications

We propose TDM/TWDM de Bruijn networks and ShuffleNets by utilizing small all-optical dilated slipped banyan networks, DSBs (Thompson, 1991). The proposed networks require fewer switches than DSBs, and smaller numbers of wavelengths than WDM de Bruijn networks and ShuffleNets. Furthermore, only one fixed-wavelength transmitter and one fixed-wavelength receiver are required for each node.

Carrier sense using subcarrier-multiplexed signaling for optical frequency division multiple access

A novel subcarrier multiplexing based carrier sense technique called SCM-CS is proposed and is experimentally demonstrated. It can prevent the contention in optical frequency division multiple access networks that use an access protocol based on a fixed-wavelength transmitter and wavelength-tunable receiver. When two or more SCM signals on the same subcarrier frequency at different wavelengths simultaneously address the same destination node, SCM-CS detects the sum of the subcarrier frequencies by using RF heterodyne detection and denies the access. SCM-CS permits node access only if the carrier sense is negative which means that the destination node is idle. In the experiment, SCM-CS is successfully performed for 6.2 Mb/s SCM signals of the subcarrier frequency of 164 MHz with the frequency difference of the optical carriers up to 40 GHz.

MAC protocols and fairness control in WDM multirings with tunable transmitters and fixed receivers

The paper illustrates novel proposals for medium access control protocols in all-optical packet networks based on WDM multichannel ring topologies where nodes are equipped with one fixed-wavelength receiver and one wavelength-tunable transmitter. Such networks provide separate slotted channels for disjoint subsets of destination nodes. Three access protocols based on local status information are described. A channel inspection capability is assumed to be available for the implementation of the access protocols. Global fairness control algorithms derived from those adopted in the Metaring high-speed metropolitan area network are also proposed. Access delays and throughputs are taken as performance Indices for a simulation-based comparison of the proposed protocols, in the case of a 16-node multiring with either balanced or unbalanced traffic. Simulation results show that the throughput limitations and the fairness problems inherent in the network topology can be overcome with relatively simple protocols.

Design Principles for Multi-Hop Wavelength and Time Division Multiplexed Optical Passive Star Networks

Wavelength Division Multiplexing (WDM) has been shown to be one of the most promising ways to exploit the enormous bandwidth of a single mode optical fiber. Networks employing WDM are commonly based on optical passive star couplers. The major cost and limitations of such networks lie in the interface (both transmitters and receivers) providing optical-electronic conversion between stations and communication media. Based on current technology, interfaces based on fast tunable devices are still in the infant stage of development at this time. Commercially available fixed wavelength devices are much cheaper and reliable. With fixed wavelength device in each station, several stations may transmit and receive on the same wavelength. Time-Division Multiplexing (TDM) is often employed for those stations accessing the same wavelength. The resulting networks, called multi-hop Wavelength-and Time-Division Multiplexed (WTDM) Networks, may require a multi-hop path to deliver packets between two stations. In this paper we study multi-hop WTDM networks where each station has only one fixed wavelength transmitter and one fixed wavelength receiver. We propose a graph model, called a Receiving Graph Model, to represent these networks such that their inherent properties can be easily understood and alternative designs can be compared. Furthermore, we discuss several design principles and theoretical performance limitations of such networks.

Exploiting the attenuation of fiber-optic passive taps to create large high-capacity LANs and MANs

A local- or metropolitan-area network (LAN or MAN) that exploits the power losses of fiber-optic passive taps so that wavelengths can be reused in different portions of the network is proposed. This wavelength reuse makes it possible to design a large, high-capacity, multichannel network with many concurrent transmissions. An arbitrary number of nodes is supported by allowing packets to take multiple hops, when necessary, to reach their destinations. In one example configuration, there are two closed circular loops of fiber, one for transmissions in the clockwise direction and one for counterclockwise transmissions. Each node has one passive tap (per fiber), which is used for both a fixed-wavelength transmitter and a fixed-wavelength receiver. >

Shuffle Net: an application of generalized perfect shuffles to multihop lightwave networks

A multihop wavelength-division multiplexing (WDM) approach, referred to as Shuffle Net, for achieving concurrency in distributed lightwave networks is proposed. A Shuffle Net can be configua19 red with each user having as few as one fixed-wavelength transmitter and one fixed-wavelength receiver, avoiding both wavelength-agility and pretransmission-coordination problems. The network can achieve at least 40% of the maximum efficiency possible with wavelength-agile transmitters and receivers. To transmit a packet from one user to another may require routing the packet through intermediate users, each repeating the packet on a new wavelength until the packet is finally transmitted on a wavelength that the destination user receives. For such a multihop lightwave network, the transmit and receive wavelengths must be assigned to users to provide both a path between all users and the efficient utilization of all wavelength channels.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Experimental demonstration of multiwavelength optical network with microwave subcarriers

The authors use the unique multiwavelength filtering capability of the acousto-optic tunable filter to demonstrate multiple broadband services with only one fixed-wavelength transmitter and receiver per user in the first experimental demonstration of a multiwavelength subcarrier network.

HYPASS: an optoelectronic hybrid packet switching system

An architecture is presented for an 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. The internal routing and interconnection utilizes a passive optical transport network with wavelength-tunable laser transmitters and fixed wavelength receivers. The single-stage multiwavelength optical interconnect provides an internally nonblocking network for large throughput routing of the bit-serial optical signals. An internal optical control network, with fixed-wavelength trouble receivers, sends output port information to the input nodes for arbitration and control. Packet buffer storage and control processing is performed by word-parallel electronic circuitry. The characteristics and device requirements for this design are presented along with results of a performance analysis of the arbitration and control protocol.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>