Bidirectional Ring Networks Research Articles

Bidirectional single-multicore-fiber spatial channel network based on a spatial cross-connect and multicore EDFA that efficiently accommodates asymmetric data traffic

In current wavelength division multiplexed (WDM) networks, capacity is deployed in a symmetrical manner, in which wavelength channels provide the same capacity in both directions. However, real data traffic in metro and backbone networks is observed to be considerably asymmetric resulting in wasted capacity in an under-loaded direction. This data traffic asymmetry is expected to increase further in the forthcoming Beyond 5G era due to newly emerging bandwidth-hungry services based on cloud computing. In such a situation, the wasted link capacity in the under-loaded direction can no longer be overlooked. In this paper, we propose a single-multicore-fiber (MCF) bidirectional spatial channel network (SCN) architecture that efficiently accommodates up and down asymmetric traffic. We present a proof-of-concept demonstration of the asymmetric bandwidth allocation in a single-MCF SCN by constructing a single-MCF bidirectional ring network testbed that comprises two spatial cross-connects based on 19-core fiber core selective switches with an M×N wavelength-selective switch and a bidirectional 7-core erbium-doped fiber amplifier with reversible optical isolators. Experimental results for bit error rate measurements of WDM optical signals traveling through different cores in different directions show there is almost no optical signal-to-noise ratio penalty for transmission through the single-MCF bidirectional ring network testbed.

Wide-Sense Nonblocking Multicast in WDM Optical Linear Array and Ring Networks with 3-Length Extension Under Longest Link First Routing

The modern scientific growths in optical networks based on wavelength division multiplexing (WDM) are more attractive to satisfy the high bandwidth requirements of the modern internet infrastructure. Moreover, they potential to satisfy the future bandwidth requirements.WDM optical networks act as the backbone for telecommunication and high-performance communication networks. Multicast communication is the simultaneous transmission of data from one source node to many destination nodes available in the network over wavelength division multiplexing. It is extensively deployed in high performance computing and communication networks. In this article, a linear array and ring networks are extended by directly linking all nodes which are separated by two intermediate nodes with additional fibers which is referred as linear array and ring network with 3-length extension. The wavelength allotment methods are proposed to realize one-to-many communication over wavelength division multiplexing optical linear array and ring with 2-length extension under longest link first routing and the minimum wavelength number needed is determined. The minimum wavelength number needed to support for the extended linear array is reduced approximately by 20% when compared with that of a linear array network and for the extended unidirectional ring is reduced approximately by 25% when compared with that of a unidirectional ring network. And also, for the extended bidirectional ring the minimum wavelength number is reduced approximately by 33% when compared with that of bidirectional ring network.

A self-stabilizing token circulation with graceful handover on bidirectional ring networks

A self-stabilizing token circulation with graceful handover on bidirectional ring networks

Scalable distributed microwave photonic MIMO radar based on a bidirectional ring network.

A scalable distributed microwave photonic multiple-input-multiple-output (MIMO) radar is proposed based on a bidirectional ring network. The network is constructed with a fiber ring on which a local node and several remote nodes are distributed. In the local node, radar signals are generated over different optical wavelengths based on external modulation. Employing wavelength-division multiplexing, the radar signals are sent to remote nodes through the fiber ring. In different remote nodes, radar signals modulated on corresponding wavelength are utilized for transmitting or photonic de-chirp processing. Benefiting from the bidirectional ring network, the proposed radar is suitable for large-scale distribution. Together with the pluggable remote nodes, the scalability of the radar is enhanced. A proof-of-concept experiment is demonstrated to verify the feasibility of the system. Measurements of two-dimensional position and velocity of targets are realized. The position error and velocity error are better than 8 cm and 0.20 m/s respectively.

FRLLE: a failure rate and load-based leader election algorithm for a bidirectional ring in distributed systems

In a distributed system, multiple nodes work together to build a highly available, reliable, resource shareable, and fault-tolerant system to achieve a common goal. Here, multiple nodes work together to complete a task, so coordination is essential among these nodes. Electing a node as a system leader from among all the nodes can be a possible solution to do the coordination. Besides coordination, the leader also controls various activities like task allocation, result aggregation, efficient resource sharing, clock synchronization, and communication among the nodes of the system. In this work, we address the leader election problem through a new leader election algorithm called Failure Rate and Load-based Leader Election (FRLLE) algorithm for bidirectional ring networks. The proposed algorithm elects a node with a minimum failure rate and load as well so that the system gets a more reliable leader that can concentrate on leadership roles and activity comfortably. Like a proper leader election algorithm, this algorithm satisfies safety, liveness, and termination conditions that help to build an efficient and consistent distributed system. This algorithm reduces the message and time complexity, which means the algorithm takes fewer time steps to elect a leader by exchanging fewer messages. We compare the simulation results of the FRLLE algorithm with the well-known existing leader election algorithms and demonstrate that the FRLLE algorithm exchanges fewer messages and takes fewer time steps to elect the leader. We further carried out a priori complexity analysis and compared the outcome with the results of the simulation to corroborate our proposal.

Fast Inter-Base Station Ring (FIBR): A New Millimeter Wave Cellular Network Architecture

Fifth Generation (5G) Millimeter Wave (mmWave) cellular networks are expected to serve a large set of throughput-intensive, ultra-reliable, and ultra-low latency applications. To meet these stringent requirements, while minimizing the network cost, the 3rd Generation Partnership Project has proposed a new transport architecture, where certain functional blocks can be placed closer to the network edge. In this architecture, however, blockages and shadowing in 5G mmWave cellular networks may lead to frequent handovers (HOs) causing significant performance degradation. To meet the ultra-reliable and low-latency requirements of applications and services in an environment with frequent HOs, we propose the Fast Inter-Base Station Ring (FIBR) architecture, where Base Stations (BSs) that are in close proximity are grouped together, interconnected by a bi-directional counter-rotating buffer insertion ring network. FIBR enables high-speed control signaling and fast-switching among BSs during HOs, while allowing the user equipment to maintain a high degree of connectivity. We demonstrate that the FIBR architecture efficiently handles frequent HO events in mmWave cellular systems, and thus more effectively satisfies the QoS requirements of 5G applications.

Wide-sense nonblocking multicast in WRMD WDM optical linear array and ring

Multicast communication is the simultaneous transmission of information from a single source to various destinations. It occurs extensively in telecommunication and advanced computing systems including enterprises operating datacenters. WDM optical networks act as the backbone for telecommunication and high performance networks. Wavelengths are scarce resources in WDM optical networks. Wavelengths usage in a network must be limited to decrease its cost and complexity. Optical linear array and ring networks find widespread application in interconnection networks including LAN and WAN. In this paper, wide-sense nonblocking multicast communication is analyzed in wavelength reusable multi-carrier distributed (WRMD) wavelength division multiplexing (WDM) linear array, unidirectional ring and bidirectional ring networks. The sufficient and necessary condition on the minimum wavelength number required for the network to be wide-sense nonblocking is derived for each of the above network topologies in the presence of a single multi-carrier light source (MCLS). An explicit wavelength allotment technique is also proposed for the above network topologies.

FBNoC: FPGA-based network on chip emulator for full-system architectural simulation of many-core systems

SoCs and chip multi processors (CMPs) usually employ a scalable interconnection network (Network-on-chip or NoC) as a communication medium. Existing simulators that can simulate such systems are mostly SW based and as such are very slow. Fast FPGA-based hardware simulators of CMP systems are gaining popularity because they allow fast and efficient exploration of several design points with multiple benchmarks. This entail emulating the NoC in these systems with different parameters and configurations. Existing hardware NoC simulators that are implemented on Field Programmable Gate Arrays (FPGAs) are not readily integrate-able with other FPGA-based multicore architectural simulators. In this work, a new FPGA-based NoC emulator (FBNoC) that can be integrated with multicore architectural simulators is proposed. It can also be used as a standalone NoC simulator. Utilizing a parametrizable latency model, FBNoC can deliver packets and accurately estimate their latencies for several NoC topologies, configurations, and parameters without the need for re-synthesize nor FPGA re-configuration. It also employs a novel multi-local port per NoC node strategy combined with two bidirectional ring networks to reduce the FPGA resource utilization while increasing the simulation speed. Requiring less FPGA resources than other FPGA-based NoC simulators, the proposed emulator can achieve more than 20,000x speedup over the popular SW NoC simulator Booksim.

Efficient exploitation of the Xeon Phi architecture for the Ant Colony Optimization (ACO) metaheuristic

In recent years, the use of compute-intensive coprocessors has been widely studied in the field of Parallel Computing to accelerate sequential processes through a Graphic Processing Unit (GPU). Intel has recently released a GPU-type coprocessor, the Intel Xeon Phi. It is composed up to 72 cores connected by a bidirectional ring network with a Vector Process Unit (VPU) on large vector registers. In this work, we present novel parallel algorithms of the well-known Ant Colony Optimization (ACO) on the recent many-core platform Intel Xeon Phi coprocessor. ACO is a popular metaheuristic algorithm applied to a wide range of NP-hard problems. To show the efficiency of our approaches, we test our algorithms solving the Traveling Salesman Problem. Our results confirm the potential of our proposed algorithms which led to distinct improvements of performance over previous state-of-the-art approaches in GPU. We implement and compare a set of algorithms to deal with the different steps of ACO. The matrices calculation in the proposed algorithms efficiently exploit the VPU and cache in Xeon Phi. We also show a novel implementation of the roulette wheel selection algorithm, named as UV-Roulette (unique random value roulette). We compare our results in Xeon Phi to state-of-the-art GPU methods, achieving higher performance with large size problems. We also exposed the difficulties and key hardware performance factors to deal with the ACO algorithm on a Xeon Phi coprocessor.

On Routing and Spectrum Assignment in Rings

We present a theoretical study of the routing and spectrum assignment (RSA) problem in ring networks. We first show that the RSA problem with fixed-alternate routing in general-topology (mesh) networks (and, hence, in rings as well) is a special case of a multiprocessor scheduling problem. We then consider bidirectional ring networks and investigate two problems: 1) the spectrum assignment problem under the assumption that each demand is routed along a single fixed path (e.g., the shortest path), and 2) the general case of the RSA problem whereby a routing decision along the clockwise and counter-clockwise directions must be made jointly with spectrum allocation. Based on insights from multiprocessor scheduling theory, we derive the complexity of the two problems and develop new constant-ratio approximation algorithms with a ratio that is strictly smaller than the best known ratio to date.

Wavelength assignment for all-to-all broadcast in bidirectional WDM optical ring with limited drops

All-to-all broadcast is to disseminate a unique message from each node to every other node in a network. This problem is significant in the context of control plane design as it relates to status information dissemination. In this paper, a wavelength assignment method to reduce the number of wavelengths is proposed to establish all-to-all broadcast in a bidirectional WDM ring network. The network model is an all-optical network, in which a message from source node can be dropped (or split) only at a limited number of destination nodes along a light path due to power loss of dropping optical signals. An expression for the upper bound on the number of wavelengths required to support all-to-all broadcast is derived for certain cases of WDM ring while for other cases, an attractive algorithm is given to identify the lengths of connection sets that can be grouped together with suitable wavelength assignment strategies. Numerical results are computed to show that the results obtained are close to the lower bound.

Zero-Hopf singularity in bidirectional ring network model with delay

This paper reports a bidirectional ring network model with delay. Zero-Hopf bifurcation is studied by using the center manifold reduction and the normal form method for retarded functional differential equation. We get the versal unfolding of the norm forms at the zero-Hopf singularity and show that the model can exhibit pitchfork and Hopf bifurcation. Some numerical simulations are given to support the analytic results, and near the zero-Hopf singularity point, this model displays quasi-periodic, double periodic and multiple periodic trajectory.

3D NoC with Inductive-Coupling Links for Building-Block SiPs

A wireless 3D NoC architecture is described for building-block SiPs, in which the number of hardware components (or chips) in a package can be changed after chips have been fabricated. The architecture uses inductive-coupling links that can connect more than two examined dies without wire connections. Each chip has data transceivers for the uplink and downlink in order to communicate with its neighboring chips in the package. These chips form a vertical unidirectional ring network so as to fully exploit the flexibility of the wireless approach that enables us to add, remove, and swap the chips in the ring. To avoid protocol and structural deadlocks in the ring, we use bubble flow control, which does not rely on the conventional VC-based deadlock avoidance mechanism. In addition, we propose a bidirectional communication scheme to form a bidirectional ring network by using the inductive-coupling transceivers that can dynamically change the communication modes, such as TX, RX, and Idle modes. This paper illustrates the inductive-coupling transceiver circuits, which can carry high data transfer rates of up to 8 Gbps per channel, for the wireless 3D NoC. It also illustrates an implementation of a wireless 3D NoC that has on-chip routers and transceivers implemented with a 65 nm process in order to show the feasibility of our proposal. The vertical bubble flow control and conventional VC-based approach on the uni- and bidirectional ring networks are compared with the vertical broadcast bus in terms of throughput, hardware amount, and application performance using a full system multiprocessor simulator. The results show that the proposed bidirectional communication scheme efficiently improves application performance without adding any inductive-coupling transceivers. In addition, the proposed vertical bubble flow network outperforms the conventional VC-based approach by 7.9-12.5 percent with a 33.5 percent smaller router area for building-block SiPs connecting up to eight chips.

Heuristic Scheme for Home Circuit Grouping andWavelength Assignment in LOBS-HC Networks

Grouping the Home Circuits (HCs) with the same source is a critical issue of Labeled Optical Burst Switching with Home Circuit (LOBS-HC). To maximize the wavelength utilization in LOBS-HC ring networks, an HC grouping and wavelength assignment scheme, called Longest Path Matching and Graph Coloring (LPMGC), is proposed. LPMGC consists of two phases: grouping and wavelength assignment. First, a heuristic algorithm, named Longest Path Matching (LPM), is proposed to group the HCs according to the longest common path matching between HCs and to make each group as large as possible. And then, Graph Coloring (GC) is introduced to assign wavelengths for HC groups. The numerical results show that the proposed scheme performances better than Complementary HC Assignment (CHA) and some other heuristics in both unidirectional and bidirectional LOBS-HC ring networks in terms of wavelength utilization.

Fault Tolerant Message Efficient Coordinator Election Algorithm in High Traffic Bidirectional Ring Network

Nowadays use of distributed systems such as internet and cloud computing is growing dramatically. Coordinator existence in these systems is crucial due to processes coordinating and consistency requirement as well. However the growth makes their election algorithm even more complicated. Too many algorithms are proposed in this area but the two most well known one are Bully and Ring. In this paper we propose a fault tolerant coordinator election algorithm in typical bidirectional ring topology which is twice as fast as Ring algorithm although far fewer messages are passing due to election. Fault tolerance technique is applied which leads the waiting time for the election reaching to zero.

QoS Provisioning for TT-TR Based OBS Ring Networks

Abstract Optical burst switching (OBS) is one of the most promising switching technologies. This paper studies the efficient OBS ring network using the TT-TR based node architecture. The TT-TR based OBS ring network can use the network resources very efficiently, but the network performance is restricted due to the limited network resources. Moreover, different network demands have different network resource requirements. It is very important to satisfy their different requirements while using the limited network resources efficiently. In this paper, Quality of Service (QoS) provisioning mechanisms are studied to solve the above mentioned problems. Two kinds of network services, namely the real-time traffic and the best-effort traffic, are considered in this paper. The real-time service is delay-sensitive that should be transmitted in a real-time manner and cannot tolerate high transmission delay; while the best-effort traffic has no strict limitation in transmission delay or loss, but the best effort are made to improve their transmission reliability. According to their different servicing requirements, different QoS provisioning mechanisms are proposed to serve them in the OBS unidirectional and bidirectional ring networks, respectively. The proposed mechanisms are evaluated and analyzed through simulation. The simulation results show that even though the proposed mechanisms cannot get absolute zero-delay or zero-loss for real-time traffic or best-effort traffic, their different requirements for delay or loss are satisfied to some significant degree.

ROADM optimization in WDM ring networks

Reconfigurable optical add–drop multiplexers (ROADMs) and tunable transceivers play an important role in optical network reconfigurability and cost saving. ROADMs provide support to dynamic traffic demands, enable new services, and save capital expenditure (CapEx) along with the operational expenditure (OpEx). Limiting the range of wavelengths that can be accessed at a node reduces costs, and possibly reduces flexibility in reconfigurability. The limited range (band size) of wavelengths is a result of the limited add/drop range of the ROADMs and/or limited tuning range of transceivers. In either case, limited reconfigurability introduces a new constraint in the wavelength assignment of connections called as the wavelength termination constraint. Limited ROADMs (L-ROADMs) can add and drop only a subset of (contiguous) wavelengths (a waveband) and are less costly than fully reconfigurable OADMs (F-ROADMs). In order to quantify the trade-offs between the number of L-ROADMs and their band sizes and compare those with F-ROADMs, optimization solutions must be obtained. In this paper, we consider two models of L-ROADMs and present optimization problems specific to each model under all-to-all traffic for ring networks. We consider two ring topologies, uni- and bi-directional rings. We give integer linear programming formulations and present heuristic solutions to minimize the worst-case band size and the total number of wavebands for the two L-ROADM types. For the uni-directional ring in the first model, we present a lower bound of ⌈ ( W + 2 ) / 2 ⌉ for the band size of ROADMs, where W is the number of wavelengths. For the upper bound, our results show that the worst-case band size of L-ROADMs is only about 65% of the full range for large network sizes. For the bi-directional ring of N nodes, our heuristic algorithm, Algorithm-Min-Bi, produces a worst-case band size of b ( w ) = N 2 − 4 N + 19 8 . This produces a reduction of 10% to 20% in the band size for typical network sizes. When the band size b s is fixed under the second model, we observe the trade-off between the total band size of L-ROADMs and the number of L-ROADMs. For both uni- and bi-directional ring networks, our results are close to optimal. We also examine the performance of our models under dynamic traffic.

Optimal online ring routing

We study how to route online splittable flows in bidirectional ring networks to minimize maximum load. We show that the competitive ratio of any deterministic online algorithm for this problem is at least , where is the size of the ring, and that the online algorithm that splits each flow inversely proportionally to the length of the flow's shortest path achieves this competitive ratio for all integers © 2010 Wiley Periodicals, Inc. NETWORKS, Vol. 57(2), 187–197 2011.

Stability and Hopf bifurcation analysis in bidirectional ring network model

Using the system parameter instead of the delay as the bifurcation parameter, linear stability and Hopf bifurcation analysis including its direction and stability of bidirectional ring network model are investigated in this paper. The main tools to obtain our results are the normal form method and center manifold theory. Numerical simulations show that the theoretically predicted values are in excellent agreement with the numerically observed behavior.

Traffic grooming in bidirectional WDM ring networks

AbstractWe study the minimization of ADMs (Add‐Drop Multiplexers) in optical WDM bidirectional rings considering symmetric shortest path routing and all‐to‐all unitary requests. We precisely formulate the problem in terms of graph decompositions, and state a general lower bound for all the values of the grooming factor C and N, the size of the ring. We first study exhaustively the cases C = 1, C = 2, and C = 3, providing improved lower bounds, optimal constructions for several infinite families, as well as asymptotically optimal constructions and approximations. We then study the case C > 3, focusing specifically on the case C = k(k + 1)/2 for some k ≥ 1. We give optimal decompositions for several congruence classes of N using the existence of some combinatorial designs. We conclude with a comparison of the cost functions in unidirectional and bidirectional WDM rings. © 2010 Wiley Periodicals, Inc. NETWORKS, Vol. 58(1), 20–35 2011