Wavelength Allocation Research Articles

Crosstalk Impact on the Performance of Wideband Multicore-Fiber Transmission Systems

This work presents an evaluation of the crosstalk impact on the signal-to-noise ratio (SNR) of long-distance C and L band wavelength-division multiplexing (WDM) systems using homogeneous multicore fibers with weakly coupled cores. It is experimentally shown that the crosstalk-induced SNR penalty is independent of the transmission distance on sufficiently long uniform links. This results from the approximately linear scaling of the noise contributions from amplified spontaneous emission, fiber nonlinearity, and crosstalk with the transmission distance. The crosstalk-induced SNR penalty on C and L band WDM long distance links is experimentally evaluated, showing significant degradation of signals located towards the long edge of the L-band. Up to 3.8 dB penalty was observed on a 3866 km link, in agreement with theoretical predictions. We perform a theoretical analysis of the wavelength allocation of densely packed channels for long distance WDM systems with and without the presence of crosstalk. It is shown that these systems favor the use of relatively short transmission wavelength ranges to minimize the crosstalk impact at long wavelengths. This contrasts with systems without crosstalk, which favor the low loss wavelength region of the transmission fiber.

ITU TWDM-PON module for ns-3

Optical fiber access systems are one of the driving forces behind the success of the Internet. Time- and wavelength-division multiplexing passive optical network (TWDM-PON) is regarded as the key technology for future Internet access networks. In this paper, we propose an ITU TWDM-PON module for the ns-3 network simulator and describe its concept and design specifications. The proposed module is developed based on the XG-PON module for ns-3. It can simulate G.989 standard-compliant data packet transmission in the upstream and downstream directions using multiple wavelength channels. It enables us to evaluate the performance issues that arise with the TWDM-PON development, including various dynamic bandwidth allocation and dynamic wavelength allocation algorithms. The proposed module is expected to become a good platform for studying future access networks composed of TWDM-PON and mobile networks by enabling us to simulate dynamic wavelength and bandwidth allocation.

Three-dimensional grid architecture supporting discretionary direct communication among optical network units in metro-access networks

In this paper, a three-dimensional grid architecture supporting discretionary direct communication among optical network units (ONUs) is proposed. By setting up one $N \times N\hspace{3pt}$N×N arrayed waveguide grating (AWG) and two coarse wavelength division multiplexers in the remote node (RN), the optimal path selection of discretionary direct communication among ONUs can be carried out. At the same time, the construction of the RN is simple. By combining with a three-band wavelength allocation, downstream and upstream signals as well as direct-communication signals can be simultaneously transmitted. By utilizing a four-level protection mechanism, three kinds of optical fiber fault protection (i.e., feeder fiber fault protection, distribution fiber fault protection, and interconnecting fiber fault protection) can be achieved. Besides, both the scalability and the reliability of the network can be greatly improved. Finally, the feasibility of the proposed architecture is demonstrated by the simulation experiment.

A learning algorithm for TWDM-PON’ DWBA with 5G fronthaul networks

Abstract Time and wavelength-division multiplexed passive optical network (TWDM-PON) is expected to be the fronthaul networks of 5G, which requires low latency and large bandwidth. In this paper, we propose a Q-learning based dynamic wavelength and bandwidth allocation (DWBA) algorithm for TWDM-PON. Simulation results show that the proposed DWBA algorithm can reduce the number of active channels by 40% and provide larger bandwidth with same wavelength number in comparation with the existing algorithms while satisfying the latency requirement of 5G fronthaul networks.

Research of Algorithms used for Routing and Assigning Wavelength in WDM Networks

The telecommunications department is the most difficult in today's communication offering the highest amount of bandwidth. With the finest prototypes and test rigs to form optical WDM technology, many companies have appeared for a particular link request, a wavelength and a path must be allocated in the WDM network. Routing and Wavelength Assignment (RWA) problem is called the assignment of a wavelength and a path to the link request, with accessible resources. The aim of this article is to analyze the algorithms for any WDM networks for efficient wavelength assignment routing protocols. As a researcher, we plan to suggest a comprehensive literature study for the development of a new algorithm for efficient allocation and appropriate wavelength usage and the routing of data packets from source to destination to overcome all failures. Before allocation, we use simulations and analyze optic fiber communication methods, various losses depending on dynamic wavelength allocation with minimum and maximum.

Optimal and Computationally Efficient Priority-Based Routing and Wavelength Allocation Strategy Supporting Qos for High-Speed Transport Networks

One of major optical network problem is to route and to assign the wavelength efficiently because of its wavelength reuse characteristics and information transparency. By utilizing the trade-off scheme between the blocking probability and setup time of the requested route, priority-based RWA (PRWA) approaches has been studied for WDM networks by introducing a priority criterion which depends on calculation of hop counts and volume of the traffic. The simulation result shows that PRWA technique reduces both the blocking probability (approx. 20%) as compare with non-priority based RWA scheme and the average end to end delay near about (10 msec.) as compare with Adaptive routing (AR) at various traffic load conditions. This approach also results in cost-effectiveness as well as reduction in the complexity of the network in comparison to earlier reported techniques

Modal crosstalk in Silicon photonic multimode interconnects.

We investigate modal crosstalk in silicon photonic MDM-based interconnects using tapered multiplexers. Crosstalk from coherent optical interference originates from variation in the physical structure and alters the transmission link performance. Through simulations and experimental work, optical crosstalk as a function of wavelength is analyzed to understand its impact in MDM and MDM-WDM dual-multiplexing applications. The detrimental effects are validated in the frequency and time domains through fabricated MDM interconnects of various lengths. Results indicate modal crosstalk must be < -22 dB to maintain a BER of 10-12. The experimental methodology assesses the optical modal crosstalk's impact on the data, towards a mitigation approach to improve the payload signal integrity and enable system-level optimization such as channel wavelength allocation.

Dynamic Upstream Wavelength Allocation Method for Power Saving in NG-EPON

Dynamic Upstream Wavelength Allocation Method for Power Saving in NG-EPON

Efficient T-CONT-Agnostic Bandwidth and Wavelength Allocation for NG-PON2

Dynamic bandwidth and wavelength allocation are used to demonstrate high quality of service (QoS) in time wavelength-division multiplexed–passive optical networks (TWDM-PONs). Both bandwidth and wavelength assignment are performed on the basis of transmission containers (T-CONTs) and therefore by means of upstream service priority traffic flows. Our medium access control (MAC) protocol therefore ensures consistency in processing alike classes of service across all optical network units (ONUs) in agreement with their QoS figures. For evaluation of the MAC protocol performance, a simulator has been implemented in OPNET featuring a 40 km, 40 Gbps TWDM-PON with four stacked wavelengths at 10 Gbps each and 256 ONUs. Simulation results have confirmed the efficiency of allocating bandwidth to each wavelength and the significant increase of network traffic flow due to adaptive polling from 9.04 to 9.74 Gbps. The benefit of T-CONT-centric allocation has also been measured with respect to packet delay and queue occupancy, achieving low packet delay across all T-CONTs. Therefore, improved NG-PON2 performance and greater efficiency are obtained in this first demonstration of T-CONTs allocated to both wavelength and time.

All-optical wavelength reservation for flexible spectrum networks using amplifier saturation and VCSEL injection

Advanced metro-access WDM optical fiber telecommunication networks use integrated wavelength switching nodes to provide efficient, flexible wavelength allocation along the link. Recent developments, together with the increase in bandwidth intense applications, have sparked great interest in flexible, grid-like optical network systems. Flexible spectrum optical network systems with nonstatic channel bandwidth, wavelength allocation, switching, and routing permit the optimum distribution of data with variable rates and modulation formats. We describe a unique technique for all-optical wavelength reservation at a forwarding flex spectrum node. The outgoing signal is locked to the incoming signal at the node, thereby guaranteeing automatic wavelength reservation and allocation. A saturated erbium-dope fiber amplifier (EDFA) is used to erase data from the incoming signal, which is then used to lock the wavelength of the forwarding node through vertical cavity surface emitting laser injection. The EDFA is shown to reduce the extinction ratio of the incoming signal from 7.3 dB to less than 1 dB (560 mdB). We show automatic wavelength reservation over 1.68 nm within the C-band, with 25.5-km transmission over G. 655 single mode fiber. Considering 50-GHz per-channel bandwidth allocations, this technique translates to four-channel operation in a typical metro-access type configuration.

Optical Burst Routing by Balanced Wavelength Allocation Under Multi-objective Quality Metrics

The optical burst switching is promising optical network technique that intends to transmit data in the form of bursts with the ability of dynamic switching between sub-wave lengths. One among the crucial issues of the OBS networks is burst loss due to suboptimal and often impediment burst scheduling and wavelength allocation strategies. Hence, the major contributions of the contemporary research in regard to OBS networks entails to portray the optimal burst routing strategies. The contribution of this manuscript is balanced wavelength allocation using differential evolution method in short referred as BWADE, which selects an optimum multi-hop route that intends to uses multi-objective QoS aspects as a fitness scale for differential evolution algorithm. The experimental study concluding that the proposed BWADE outperforming the other contemporary routing approaches through simulation outcomes.

Wavelength assignment in quantum access networks with hybrid wireless-fiber links

We propose a low-complexity near-optimal wavelength allocation technique for quantum key distribution access networks that rely on wavelength division multiple access. Such networks would allow users to send quantum and classical signals simultaneously on the same optical fiber infrastructure. Users can be connected to the access network via optical wireless or wired links. We account for the background noise present in the environment, as well as the Raman noise generated by classical channels, and calculate the secret key generation rate for quantum channels in the finite-key setting. This allows us to examine the feasibility of such systems in realistic scenarios when the secret key exchange needs to be achieved in a limited time scale. Our numerical results show that, by proper choice of system parameters for this noisy system, it is possible to exchange a secret key in tens of seconds. Moreover, our proposed algorithm can enhance the key rate of quantum channels, especially in high noise and/or high loss regimes of operation.

TWDM-PON中支持区分服务的节能动态波长带宽分配算法

TWDM-PON中支持区分服务的节能动态波长带宽分配算法

A novel centralized beamforming scheme for radio-over-fiber systems with fixed wavelength allocation

A novel centralized beamforming scheme for radio-over-fiber systems with fixed wavelength allocation

Adaptive dynamic wavelength and bandwidth allocation algorithm based on error-back-propagation neural network prediction

With the emergence of new services such as high-definition video, cloud computing and virtual reality, Wavelength Division Multiplexing/Time Division Multiplexing-Passive Optical Network (WDM/TDM-PON) has become a key technology for future access network. The development of Software Defined Networking (SDN) and machine learning also brings new opportunities to the flexibility of WDM/TDM-PON. In this paper, an Adaptive Dynamic Bandwidth Allocation algorithm based on error-back-propagation Neural Network Prediction (ADBA-NNP) was proposed to reduce the Round-trip-time (RTT) delay in the bandwidth-scheduling period. A Dynamic Wavelength Allocation (DWA) algorithm and a novel architecture of WDM/TDM-PON was proposed to simple the multi-carrier source. The experimental results validated that the proposed algorithm could dynamically allocate wavelengths under multi-carrier at 12.5G intervals. Compared with the traditional algorithms, the proposed algorithm could reduce the transmission delay by 25%.

Quasi-Passive Reconfigurable Node for 5G Mobile Optical Backhaul Networks

A novel multi-dimensional quasi-passive reconfigurable (MD-QPAR) node for 5G mobile backhaul optical WDM mesh networks is proposed in this paper. The proposed MD-QPAR is capable of providing dynamic power and wavelength allocations for signals from any input port(s) to any output port(s). Each input/output port is connected to one possible direction or the local wireless nodes, and hence, the data rate, flexibility, robustness, and reliability requirements in 5G backhaul networks can be satisfied. In addition, the MD-QPAR is “quasi-passive,” where it only consumes power during network reconfigurations and there is no power consumption during steady-state operations, to enable high energy efficiency. Three possible MD-QPAR structures are proposed and studied. Simulations under the optical Flow traffic assumption are carried out and the signal blocking probability and the scalability are investigated. Proof-of-concept experiments are also undertaken and the MD-QPAR with Structure II is demonstrated. Results show that dynamic power and wavelength distributions from any input port(s) to any output port(s) can be realized, and the power penalty due to the MD-QPAR is limited to <0.5 dB.

Wavelength allocation for all-to-all broadcast in bidirectional optical WDM modified ring

All-to-all broadcast is to distribute an exclusive message from each node to all the other nodes in the network. This is a vital requirement in high performance computing and communication networks including datacenter operations. Such networks may spread across thousands of nodes by means of WDM optical networks. A ring topology is an important form of network topology as it is simple, easy to deploy and fault tolerant. Few previous works suggested connecting the alternate nodes of a backbone naive ring network, and called as modified ring to support huge traffic density with decreased delay, reduced call blocking probability and increased survivability. One of the major design issues in wavelength-division multiplexed networks is to aim for reduction in the number of wavelengths usage so as to reduce network cost and complexity. In this paper, for the modified ring network, all-to-all broadcast communication is studied under single hop routing model by means of a heuristic technique, which supports to identify and group non overlapping connections. Explicit wavelength allocation techniques are given to allot unique wavelengths for various groups of non overlapping connections. The results obtained shows that wavelength requirements for a modified ring is considerably reduced than that required for a naive ring network and hence makes it attractive for optical control plane.

A large-scale nesting ring multi-chip architecture for manycore processor systems

The optical network on chip (ONoC) paradigm has emerged as a promising solution to multi-core/many-core processor systems for offering enormous bandwidth and low power consumption. As chip multiprocessors (CMPs) scale to unprecedented numbers of cores, the performance of next-generation CMPs will be bounded by the process yield and power density of single chip. In earlier work we proposed a multi-chip ONoC architecture that scales to large numbers of CMPs and delivers high performance in terms of delay and throughout. Building on that work, in this paper we propose an optimized architecture for integrating a large number of cores into chips with a novel control strategy, including a contention resolution scheme and a resource reservation scheme. The proposed control strategy is crucial to large scale ONoCs, because the resource reservation scheme ensures efficient wavelength allocation for the traffic while the contention management scheme is effective in reducing the impact of contentions. To sustain good performance and energy efficiency of large-scale ONoC, the topology is optimized to reduce the average transmission distance with minimum increase of power consumption. We evaluate the proposed architecture within a 1000-core processor system and compare it with CMesh and several previously proposed topologies with different control strategies. The simulation results show that, our new large-scale architecture can achieve better performance on throughput and delay.

Adaptive wavelength allocation pattern for an online DWBA in the NG-EPON

We propose an adaptive wavelength allocation pattern for scheduling multi-wavelength ONUs in the NG-EPON. Proposed wavelength allocation patterns make online decisions for ONU wavelength allocation based on an adaptive threshold that reflects both ONU’s absolute bandwidth request size as well as the relative bandwidth request size to other ONUs. The proposed wavelength allocation pattern has low complexity and good network performance. Simulation results show that the proposed wavelength allocation pattern achieves small packet delay, huge bandwidth throughput, and a low packet loss ratio in different network conditions, which outperforms the existing wavelength allocation patterns for the NG-EPON.

Routing and allocation of wavelengths in Elastic Optical Networks: a Survey

Objectives: The current technologies of wavelength routing and allocation of available for WDM networks are no longer applicable in Elastic Optical Networks (EON), since all their connections are allocated in a fixed manner, as provided for ITU. Therefore, the topic concerning routing and allocation of resources in EON is relevant given the growth projected in web traffic. This survey includes the evolution, main characteristics, and the process of routing and allocation of wavelengths required by EON. Methodology: The processes of allocation of sub-wavelengths and those of super-wavelengths are presented, as well as the multiple storage for different transmission rates and the principle of spectral contiguity. The process of routing and allocation taking OFMD into account is explained. Findings: In this study, we present a survey with routing and allocation techniques of wavelengths that improve the spectral efficiency of EON. Application/Improvements: This survey provides a wide knowledge on the methods to improve the spectral efficiency in EON. Such efficiency can promote an advance in new routing and allocation techniques for the optical transport networks. Keywords: Elastic Optical Networks, EON, Optical Networks, Routing, WDM