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Wavelength Assignment in Multi-Carrier Distributed Optical Ring Networks With Wavelength Reuse
Journal of Optical Communications and Networking
Abstract
This paper investigates the problem of wave- length assignment in wavelength reusable multi-carrier distributed (WRMD) wavelength-division-multiplexing (WDM) ring networks. In conventional WDM ring networks, each edge node (EN) has its own light sources, and optical channels, called lightpaths, are established by using optical carriers gen- erated from laser diodes (LDs) at the source EN. However, such networks will suffer from the need for complicated wavelength management (e.g., monitoring LDs, avoiding wavelength collision) in the future since each EN requires a large number of LDs to deal with the exponential increase in traffic. On the other hand, a WRMD ring network overcomes this problem. In this network, lightpaths between source and destination ENs are established by using carriers generated from a centralized multi-carrier light source. Moreover, the carrier regeneration technique is applied for the purpose of reducing the number of wavelengths used for lightpath establishment. Although opti- cal carrier regeneration reduces the number of wavelengths, the quality of the regenerated carrier is slightly degraded after carrier regeneration. Therefore, in the WRMD network, the allowable number of carrier regenerations per wavelength must be limited in order to avoid communication error. This paper formulates the wavelength assignment problem, minimizing the number of wavelengths needed to establish all requested lightpaths, as the vertex coloring problem, and then an integer linear programming (ILP) solution is provided. Since ILP problems are non-deterministic polynomial-time- (NP-) complete, a heuristic algorithm is developed. Numerical results indicate that our developed algorithm performs well in our test cases. It is observed that one and two carrier regen- erations per wavelength reduce the number of wavelengths for lightpath establishment by approximately 50% and 60%, respectively, compared to that without carrier regeneration. The results also show that regenerating carriers more than two times per wavelength has little effect on the required number of wavelengths regardless of the number of ENs.
... The centralized and distributed schemes is represented the (DWA) algorithms. In [3]- [6] the centralized scheme has been implemented. In [3], they investigate the problem of wavelength assignment in wavelength reusable multi-carrier distributed (WRMD) wavelength-division-multiplexing (WDM) ring networks. ...
... In [3]- [6] the centralized scheme has been implemented. In [3], they investigate the problem of wavelength assignment in wavelength reusable multi-carrier distributed (WRMD) wavelength-division-multiplexing (WDM) ring networks. In conventional WDM ring networks, each edge node (EN) has its own light sources, and optical channels, called light-paths, are established by using optical carriers generated from laser diodes (LDs) at the source EN. ...
... In the network in figure (1), there are availability for the calls {(1,2), (2,3), (2,4), (1,3) and (1,4)}. There are five calls for each wavelength available in are assumed, the number of calls available in this network will be ten. ...
Wavelength assignment is a widely research object and especially in optical networks. The centralized algorithm has been proposed in this paper and there are two scenarios for our algorithm. The main effect and improvement in the algorithm is to save network capacity by decreasing network capacity after each wavelength assignment. The term network capacity and network capacity decreasing are well investigated and analyzed. There are also mathematical equations for them have been formed and created. By our knowledge, this is the first time the equations are created. The performance of our network is mainly depending on the perfect complete binary, ternary and quaternary. The idea is rare investigated in perfect complete network, while the other works usually study random networks. The work in this paper is concentrated on centralized algorithm wherever the future work will compare the distributed algorithms also. The research is found the blocking probability, capacity decreasing and the time delay for different networks and compared with different algorithms. The results show the clear improvement in our algorithm. These algorithms are suitable for using in passive optical networks, because we did not use any active devices in our scenarios.
... It is assumed that add/drop of information between the nodes and the ring is technically achievable at each node. Although the time synchronization via W-Wi of nodes arranged in ring structures has not been studied elsewhere, the ring topology of optical network itself has been well examined in the literature such as [8] and [9]. ...
... Before conclusion, we put a few remark regarding important research topics in the future. First, in the present study, we have assumed a ring-structure network due to its simplicity and high technological relevance to the optical ring network studied in the existing literature [8,9]. However, other network structures such as tree, star, and their combinations may be interesting for future investigations. ...
The growing demand of high-bandwidth and low-latency information transfer in information and communication technologies such as data centers and in-vehicle networks has increased the importance of optical communication networks in recent years. However, complicated arbitration schemes can impose significant overheads in data transfer, which may inhibit the full exploitation of the potential of optical interconnects. Herein, we propose an arbitration protocol based on precision time synchronization via wireless two-way interferometry (Wi-Wi), and numerically validate its efficiency including the ability to impose a strict upper bound on the latency of data transfer. We introduce the notion of arbitration point (AP) for a designated time duration, which is shared by all nodes thanks to the time synchronization by Wi-Wi, to determine data transmission while ensuring avoiding collision. Compared with the conventional carrier sense multiple access/collision detection (CSMA/CD)-based approach, a significant improvement in the data transfer was observed especially in the cases with high traffic flow rate. Furthermore, we conducted a proof-of-principle experiment for Wi-Wi-based data transfer between two electrically connected nodes and confirmed that the skew was less than 300 ns and remained stable over time. Conversely, non-Wi-Wi-based data transfer exhibited huge and unstable skew. These results indicate that precision time synchronization is a promising resource to reduce the communication overheads and ensure low latency for future networks and real-time applications.
... One solution is shown in Fig. 1 (b), the multi-carrier distributed opti- cal network with wavelength reuse capability [1,2]. This network is called the wavelength reusable multi-carrier distributed (WRMD) network. ...
... Wavelength assignment for the WRMD network was proposed in [2]. None of the source nodes include a LD, and instead each directly receives a generated carrier wavelength from the MCLS node or a reused carrier wave- length from other destination lightpath request node. ...
This letter presents a mathematical model that mini-mizes the number of wavelengths required for wavelength assignment in a wavelength-reusable multi-carrier-distributed (WRMD) wavelength division multiplexing mesh network. None of the source nodes in the WRMD network is equipped with laser diodes. It receives carrier wave-lengths from a multi-carrier light source or reuses carrier wavelengths from other established lightpaths. The loop problem may occur in mesh topologies when a source node selects a reused carrier wavelength from a destination lightpath node, if we consider only flow conservation con-straints, which are usually adopted in conventional network design. We solve the loop problem by formulating constraints that reflect the spe-cial characteristics of the WRMD network. To support the development of heuristic algorithms towards large-scale networks, our mathematical model, which can provide reference values including upper and lower bounds, is useful for benchmarks.
... First, in the present study, we have assumed a ring-structure network due to its simplicity and high technological relevance to the optical ring network studied in the existing literature 8,9 . However, other network structures such as tree, star, and their combinations may be interesting for future investigations. ...
The growing demand of high-bandwidth and low-latency information transfer in information and communication technologies such as data centres and in-vehicle networks has increased the importance of optical communication networks in recent years. However, complicated arbitration schemes can impose significant overheads in data transfer, which may inhibit the full exploitation of the potential of optical interconnects. Herein, we propose an arbitration protocol based on precision time synchronization via wireless two-way interferometry (Wi-Wi), and numerically validate its efficiency including the ability to impose a strict upper bound on the latency of data transfer. Compared with the conventional carrier sense multiple access/collision detection (CSMA/CD)-based approach, a significant improvement in the data transfer was observed especially in the cases with high traffic flow rate. Furthermore, we conducted a proof-of-principle experiment for Wi-Wi-based data transfer between two electrically connected nodes and confirmed that the skew was less than 300 ns and remained stable over time. Conversely, non-WiWi-based data transfer exhibited huge and unstable skew. These results indicate that precision time synchronization is a promising resource to significantly reduce the communication overheads and ensure low latency for future networks and real-time applications.
... Wavelength reusable multi carrier distributed (WRMD) WDM network was introduced to overcome this problem [1]. WRMD-WDM networks as shown in uses a multi-carrier light source (MCLS). ...
This paper presents a mathematical model for wavelength assignment to minimize number of wavelengths needed in wavelength reusable multi-carrier distributed (WRMD) wavelength-division-multiplexing (WDM) mesh networks. The result shows that reusing the carrier wavelength reduces the number of wavelengths needed WRMD-WDM networks.
In the past decade optical network is growing very rapidly due to the low noise, less bit error rate as well as bandwidth utilization of the network. In this paper explored the bandwidth utilization with the improved gain with less noise and low bit error rate. Previously worked had been done on this area up to the 2nd stage of the optical networks. Previous worked explain the utilization of the bandwidth also explore the allocation of bandwidth in between the two different networks. They also find out the different optimized parameters like bit error rate, delay, gain, and low noise using different methods. But this paper explored up to the fifth stage of the optical network with the optimum parameters has been found out after the simulation. It also explains the bandwidth reuse to the next level of the optical network without any delay provided in between the two consecutive stages. In this explored the future prospective of the next generation optical network and also explain the different module of the stages.
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.
This paper proposes a routing and wavelength assignment (RWA) scheme that supports multiple multi-carrier light source (MCLS) nodes to minimize the number of required wavelengths for wavelength-reusable multi-carrier-distributed (WRMD) mesh networks. There are two unique features in these networks. First, a light source, called the MCLS, is required, which eases the difficulty of controlling many light source devices. Second, optical carriers are reused to improve the efficiency of wavelength usage. For large-scale networks, there may be a need to have more than one MCLS node for using resources efficiently. To utilize wavelength resources efficiently, we formulate the RWA problem as an integer linear programming (ILP) problem to obtain the minimum number of required wavelengths to satisfy the given lightpath setup requests. Numerical results show that the ILP approach with two carrier regenerations for the WRMD network achieves the same numbers of wavelengths as the optimal ones. In addition, the suitable number of the MCLS nodes is shown to reduce the number of required wavelengths for lightpath establishment.
This paper proposes a routing and wavelength assignment (RWA) scheme that minimizes the number of required wavelengths for wavelength-reusable multi-carrier-distributed (WRMD) mesh networks. These networks have two unique features. First, only one light source, called the multi-carrier light source (MCLS), is required, which eases the difficulty of controlling many light source devices. Second, optical carriers are reused to improve the efficiency of wavelength usage. Since there are differences between the WRMD network and the conventional network, an efficient RWA scheme for the WRMD network is needed for wavelength-resource-efficient lightpath establishment. To realize efficient wavelength usage, we first formulate the RWA problem as an integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths to satisfy the given requests. For large-scale networks, the ILP approach is not practical solution times. A heuristic RWA scheme is introduced in this paper to solve the RWA problem. Simulation results show that the proposed heuristic scheme with two carrier regenerations for the WRMD network approaches the near-optimum number of wavelengths. In addition, the optimum placement of the MCLS node is shown to reduce the number of required wavelengths for lightpath establishment, and achieve the optimum number of wavelengths.
This paper proposes a wavelength assignment method for all-to-all broadcast in wavelength reusable multi-carrier distributed (WRMD) wavelength division multiplexing (WDM) linear array and ring networks with wavelength reuse. An expression on the minimum number of wavelengths required to establish all-to-all broadcast is also derived for the networks. It is observed that one carrier regeneration per wavelength significantly reduces the number of wavelengths compared to that without carrier regeneration. The results also show that regenerating carriers more than once has little effect on the required number of wavelengths.
We demonstrate a distributed multicarrier reusable network (DMRN) for regional and metro areas, based on dense wavelength-division multiplexing (DWDM) transmission with reconfigurable optical add/drop multiplexers (ROADMs). To eliminate the multiple distributed laser-diodes (LDs) at each access node in conventional ROADM networks, optical carriers generated by a centralized multicarrier light source (MCLS) are distributed to the access nodes, and they are used for node-to-node data transmission. The ROADM employed at each access node is used not only to “add” and “drop” data, but also to “drop” optical carriers. Moreover, to improve the wavelength utilization efficiency of the carriers distributed by the MCLS in the network, we proposed a technique called optical carrier regeneration (OCR), whereby the distributed carriers can be reused in each access node. This technique has a simple scheme and enables us to reuse the carriers that were already utilized for data transmission between prior source and destination nodes. In this work, we numerically analyze the scalability of our proposed DMRN in terms of the number of nodes, the span length, and the cascadability of the OCR. Moreover, we conduct a DMRN experiment using 10.7 Gb/s × 4 channels DWDM transmission and compare the transmission performances for various span lengths, for the first time. The results show that the DMRN will be useful for wide-area metro networks with high transmission performances.
This study investigates a heuristic routing and wavelength assignment (RWA) scheme for an optical-carrier-reusable ring network. This network has two unique features. First, only one light source, called the multi-carrier light source, is required which eases the difficulty of controlling many light source devices. Second, optical carriers are reused in order to improve the efficiency of wavelength usage. Given the target of wavelength-resource-efficient channel establishment, performance of the heuristic RWA scheme is evaluated. To realise efficient wavelength usage, the authors formulate the RWA problem as an integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths for given requests. With the ILP approach, the calculation process is not tractable in practical time. The heuristic RWA scheme introduced in this study solves the RWA problem. This scheme consists of two algorithms. Channel routes are obtained by the routing algorithm, and the wavelength assignment algorithm is then performed to assign a wavelength to each route. Moreover, two candidates, considering the shortest path and considering the avoidance of wavelength conversion, for the routing algorithm are examined. Numerical results show that the first candidate is more suitable in terms of reducing the number of required wavelengths than the second candidate.
A simple low-cost, synchronized, in-band, and stable signaling insertion and detection scheme is proposed for the reconfigurable wavelength division multiplexing and orthogonal frequency division multiplexing (WDM-OFDM) access network. The low-frequency signaling is generated with the optical OFDM signal. Such signaling data can be simply detected by using a low-speed photon diode cascaded with an electrical low-pass filter. The low-frequency insertion and detection (LFID) induced impairments are analyzed theoretically and verified through experiments. The principle to design LFID is derived and the optimization of such a scheme is discussed. The LFID scheme is demonstrated for a reconfigurable WDM-OFDM optical network with 15 Gb/s per wavelength. The power penalty of signaling after 12.5 and 100 km is 0.35 and 0.85 dB at bit error rate (BER) of 3.44 × 10-8, respectively. The ON-OFF keying insertion induced power penalty for BER at 2.4 × 10-4 is 0.9 dB for back-to-back, 1.1 dB for 12.5 km, 1.5 dB for 100 km, respectively. There is only 0.6 dB additional penalty caused by the transmission fiber of 100 km, which demonstrates that this signaling scheme does not increase system penalty considerably.
We describe a superdense wavelength-division-multiplexing (WDM) metro ring network comprising multiwavelength generators and tapped-type optical add/drop multiplexers (OADMs) that simply add/drop optical signals through an optical coupler. This configuration is suitable for a ring network that handles a huge number of wavelengths with narrow channel spacing, for example, 12.5 GHz. The design guidelines of this superdense WDM metro ring network using multiwavelength generators and tapped-type OADMs are presented, and its performance is estimated based on numerical simulations. Based on the design guidelines, the feasibility is confirmed using the developed prototypes, and the validity of the numerical simulations is verified over 12.5 GHz spaced, 256×1.25 Gbit/s metro ring networks with a total ring length of 200 km of single-mode fiber.
Over-10000-channel multi-carriers with uniform channel spacing of 2.5GHz are generated from a supercontinuum (SC) multi-carrier source, which uses two parallel SC conversion sections. More than 3100 channels in the C+L-bands are confirmed to offer Q-factors sufficient for GbE transport.
We demonstrate optical carrier regeneration for wavelength reuse in a multicarrier distributed OADM network. It is possible to achieve a high-quality regenerated signal even though the employed data signal for wavelength reuse is drastically degraded.
We experimentally demonstrate optical carrier regeneration for carrier wavelength reuse in a multicarrier distributed wavelength-division-multiplexing network. The regenerated signal with a wavelength well matched with the reused data signal and has high signal quality.
Described is a phase-locked multi-carrier light generator with a flattened spectral envelope that contains two phase modulators and a dispersion medium. By adopting a chirped fibre Bragg grating as a dispersion medium instead of a long normal dispersion fibre, the stability of the optical output spectrum can be increased and the size of the multi-carrier light generator reduced. A prototype has been built with this configuration, that generates a 61 carrier light with a power deviation of less than 8 dB.
This paper presents an optical carrier supply module (OCSM) that functions as a common multicarrier light source, a wavelength bank, for superdense wavelength-division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing. A novel sideband generator based on a sinusoidal amplitude-phase hybrid modulation scheme is the key technique. The sideband generator generates nine flattened optical sidebands within 3 dB from one seed light source, and the input from wavelength-division multiplexing (WDM) seed carriers expands the number of generated sidebands. Scalability against the number of wavelengths is achieved by increasing the number of seed carriers used. The SD-WDM system employing OCSM reduces the number of laser diodes (LDs) and attendant wavelength monitoring/stabilization circuits. Multiple distributions to SD-WDM networks by splitting the OCSM output can promote this effect. We designed OCSM and experimentally investigated its performance pertaining to the electrical signal-to-noise ratio (SNR) of the OCSM output. The experimental results show the wavelength scalability to 1000 channels. We also developed an OCSM prototype that generated 12.5-GHz-spaced 256-channel WDM carriers. All the generated carriers exhibit the electrical SNR of more than 31.5 dB at 2.5 Gb/s and the power flatness of within 3 dB. The distribution over 100 SD-WDM networks is experimentally confirmed.
We propose and experimentally demonstrate a wavelength division
multiplexed (WDM) ring network employing a centralized multiwavelength
light source to supply all nodes with optical carriers of precise
wavelength spacing. This approach overcomes the problem of monitoring
and controlling the wavelengths of optical sources dispersed throughout
the network. A four-node test bed using optical lattice-type add-drop
multiplexing filters and a multiwavelength light source based on
resonant cavity-enhanced four wave mixing in a Fabry-Perot laser diode
was constructed to demonstrate the feasibility of the proposed method.
The effects of coherent crosstalk in such networks are analyzed, and
methods such as phase scrambling or the use of a pulsed optical source
are shown to significantly reduce the effects of coherent crosstalk. The
use of four-port add-drop multiplexer (ADM) filters instead of 1:n
optical wavelength multiplexer/demultiplexers to implement the
wavelength add-drop function at each node is shown to lead to a broader
transmission bandwidth for each channel and also easier compatibility
with the coherent crosstalk suppression mechanisms described
We consider large optical networks in which nodes employ
wavelength-routing switches which enable the establishment of
wavelength-division-multiplexed (WDM) channels, called lightpaths,
between node pairs. We propose a practical approach to solve routing and
wavelength assignment (RWA) of lightpaths in such networks. A large RWA
problem is partitioned into several smaller subproblems, each of which
may be solved independently and efficiently using well-known
approximation techniques. A multicommodity flow formulation combined
with randomized rounding is employed to calculate the routes for
lightpaths. Wavelength assignments for lightpaths are performed based on
graph-coloring techniques. Representative numerical examples indicate
the accuracy of our algorithms
An architectural approach that meets high bandwidth requirements
by introducing a communication architecture based on lightpaths, optical
transmission paths in the network, is introduced. Since lightpaths form
the building block of the proposed architecture, its performance hinges
on their efficient establishment and management. It is shown that
although the problem of optimally establishing lightpaths is
NP-complete, simple heuristics provide near optimal substitutes for
several of the basic problems motivated by a lightpath-based
architecture