Classification of multiplexed coaxial holograms based on all-optical diffraction networks

The network coding paradigm enables better resource utilization and improves throughput in communication networks, thus, employing network coding in all-optical multicast networks will facilitate the future development of effective optical networks. However, some properties of optical networks, such as limited buffering and weak logic operation capabilities, restrict the application of network coding in optical multicast networks. So in this paper, several problems of adapting network coding to all-optical multicast networks are addressed: 1) Put forward a novel strategy to distribute encoding vectors in all-optical networks, and, 2) design a framework of Encoding Node Model to support the special scheme of encoding vectors assignment in practical networks. Moreover, the experimental demonstration indicates that it is feasible and efficient to employing network coding in optical-layer multicast traffic.

With the standardizations of 400GE and 400G completed or near completion, the attention is now refocused to next generation techniques with larger bit rates, i.e. 800G. We can see that current research commonly aims to short-reach or metro transmission for sharing key components with 400G, while ultra-long-haul transmission (typically ≥ 1500km) based on 800G is still in unknown state. Moreover, all-optical networking with OXC and ROADM is being gradually deployed all around the world, which further increases transmission performance requirement. According to past progress, it is urgent for us to analyze and clarify the requirements of 800G transmission systems for ultra-long-haul all-optical backbone networks. This work provides the technological prospection and requirements of 800G transmission systems for ultra-long-haul all-optical backbone networks. Firstly, the field network status and basic technical requirements for 800G are analyzed. Our record real-time 10-λ×800-Gb/s sub-carrier-multiplexing 95-GBd DP PCS-64QAM transmission over 2018-km G.654.E Fiber with pure backward distributed Raman amplification shows that reusing the components of current 400G technique is not the future direction. By numerically simulating the transmission performances of non-fully-loaded and fully-loaded DWDM scenarios, symbol rate higher than 180GBd, G.654.E, and optical bandwidth ≥ 12THz are necessary.

This work focuses on the routing and wavelength assignment (RWA) problem in all-optical DWDM networks with sparse wavelength conversion (SWC) capabilities. By sparse wavelength conversion, we mean that nodes within the optical network domain might or might not support optical wavelength conversion. For these nodes that support optical wavelength conversion, the number of wavelength converters might be limited. As such, optical lightpaths might or might not be able to find the wavelength conversion resources that might be needed for it to be established. In this work, we present the RWA problem in all-optical WDWM networks with sparse wavelength conversion capabilities (RWA-SWC). We also provide integer linear programming (ILP) formulation for static lightpath establishment (SLE) in all-optical networks with sparse wavelength conversion capabilities. Finally, we propose a new opaque extension to the OSPF routing protocol to advertise wavelength usage and converter availability throughout the optical network domain.

The method in which Routing and Wavelength Assignment (RWA) of connection requests is performed in optical WDM networks, can appreciably affect resource consumption. The blocking probability for lightpath requests increases significantly with increase in resource consumption. Thus the method of performing RWA should be such that it minimizes consumption of network resources. RWA in all-optical networks is an NP-Complete problem. This paper proposes six new heuristic algorithms for static RWA in all-optical mesh networks that are not only efficient in terms of resource conservation but can also solve the RWA problem effectively in polynomial time. Comparisons show that the proposed algorithms perform better than some earlier well-known strategies.

The effects of an attack connection can propagate quickly to different parts of an all-optical transparent network. Such attacks affect the normal traffic and can either cause service degradation or outright service denial. Quick detection and localization of an attack source can avoid losing large amounts of data in an all-optical network. Attack monitors can collect the information from connections and nodes for diagnostic purpose. However, to detect attack sources, it is not necessary to put monitors at all nodes. Since those connections affected by the attack connection would provide valuable information for diagnosis, we show that by placing a relatively small number of monitors on a selected set of nodes in a network is sufficient to achieve the required level of performance. However, the actual monitor placement, routing, and attack diagnosis are challenging problems that need research attention. In this paper, we first develop our models of crosstalk attack and monitor node. With these models, we prove the necessary and sufficient condition for one-crosstalk-attack diagnosable networks. Next, we develop a scalable diagnosis method which can localize the attack connection efficiently with sparse monitor nodes in the network.

The rapid expansion and integration of ICT (information and communication convergence technologies) technology, and large-scale deployment of audio, video and data applications, has prompted the State to promote the concept of all-optical networks. However, due to various technical bottlenecks, this goal has not been easily achievable, particularly in light of network access, transmission, and switching that have proven to be large technical problems. This paper deals with the end of all-optical access, transfer, and exchange of technical problems, to achieve an all-optical network access layer, together with its core POF (Plastic Optical Fiber) based media and equipment to realize fully optical networks that are useful for social-scale users of all-optical business needs in industries such as electricity, petroleum, and transportation and other private all-optical business networks.

A major obstacle in realizing fast packet switching in all-optical networks is the large tuning delays of tunable optical devices. This article proposes a multiaccess scheme for all-optical local area networks that employs both wavelength and code concurrency. In this scheme, several users share a wavelength channel through code multiplexing. The delay performance of hybrid wavelength/code division multiaccess is obtained under a simple, suboptimal access protocol based on cyclic search. Due to the reduction in the number of wavelength channels without an associated reduction in transmission concurrency, hybrid multiaccess is robust against tuning delays. At a given network throughput, the hybrid scheme achieves considerably lower delays than that of Wavelength Division Multiple Access even with a small amount of code concurrency. Conversely, the hybrid network can support a higher load when there is a maximum allowable value for the average packet delay.

A research program at The MITRE Corporation was developed to examine all-optical networks. The central element in this all-optical local area network research testbed was an optical crossbar switch employing semiconductor optical amplifiers (SOAs) as the switching and gain elements. One of the initial applications demonstrated on this all-optical testbed was the capability to transmit amplitude modulated (AM) analog signals through this network. The successful implementation of this capability demonstrates that analog imagery, telemetry, radio frequency communications, and sensor information can be distributed over a switched all-optical network. The principal challenge associated with the transmission of AM signals through the all-optical network are the limitations imposed by the SOAs in the switch. These devices exhibit non-linear transfer characteristics, have limited dynamic range, and high noise levels. This paper will describe the techniques developed to demonstrate acceptable video signal transmission performance through the all-optical switched testbed using FM modulation and microwave subcarrier technology.

In view of the serious environmental interference of coal mine underground, the inconvenient power supply of underground equipment and the existence of passive serial series series number of existing F5G underground network network, explore a new coal mine underground all-optical network redundancy technology networking scheme, realize the multi-stage series of passive light branches of the mine, Solve the problem of low number of underground optical branches in series and anti-interference of communication. Based on the principle of all-optical network network, this paper expounds the redundancy protection mechanism of all-optical network group, and designs a wide-ranging coverage scheme of fiber optic whole mine through precision calculation and analysis. Through laboratory verification and coal mine roadway simulation experimental data show that the all-optical redundancy technology network scheme can realize the underground passive light multi-stage serialization, while ensuring the priority and reliability of underground gas system. At the same time, the priority and reliability of the underground gas system are guaranteed; the scheme parameter comparison table is suitable for various types of coal mines and can be used as a reference for coal mine users in the construction of underground all-optical networks.

In this paper, we propose and evaluate a new concept of traffic aggregation in wavelength-division multiplexing (WDM) optical networks that aims at eliminating both the bandwidth underutilization and the scalability concerns that are typical of all-optical wavelength-routed networks. Our objective is to reduce the network cost while preserving the benefits of all-optical wavelength-routed networks. In order to assess the efficiency of our proposal, all underlying network costs are compared. These costs include that of the transceivers and cross-connect ports required at node level, as well as the number of wavelengths. Our results show that the proposed aggregation technique can significantly reduce the network cost

This paper deals with resilience in all-optical networks. The main disadvantage when designing all-optical label swapping networks is the enormous dimensions an all-optical node can have. The node's size relates directly to the number of Label Switched Paths passing through the node. In this paper, we discuss how the dimensions of the all-optical node alter when introducing resilience in label swapping and stripping networks. We compare the node dimensions for different recovery strategies and different all-optical networking approaches.

This paper presents a study on dynamic wavelength routed all-optical networks by simulating traffic on all-optical networks. A performance study is carried out on dynamic all-optical networks for fixed and free routing. It is explained how multiple fibers correspond to limited wavelength conversion, and it is explained why the presence of wavelength converters increase the complexity of optical cross connects. We find that both free routing and wavelength conversion lowers the blocking probability significantly. The new contribution is that we determine the gain in blocking probability as function of the number of fibers per link and the offered load. We find that multiple fibers reduce the effect of wavelength converters significantly.

Existing research has shown that the mode in which Routing and Wavelength Assignment (RWA) of lightpath requests are carried out can significantly affect resource consumption in optical WDM networks. The increase in resource consumption in turn directly affects the blocking probability for future lightpath requests. The RWA problem in all-optical networks is known to be NP-Complete. In this paper we propose two heuristic dynamic RWA algorithms namely MLBF (Minimum Load Best Fit) and MLF (Minimum Load Fit) for all-optical mesh networks that can solve the RWA problem effectively in polynomial time. Performance comparisons show that the proposed algorithms outperform some earlier well-known strategies.

In an all-optical wide area network, some network nodes may handle heavier volumes of traffic. It is desirable to allocate more full-range wavelength converters (FWCs) to these nodes, so that the FWCs can be fully utilized to resolve wavelength conflict. We propose a set of algorithms for allocating FWCs in all-optical networks. We adopt the simulation-based optimization approach, in which we collect utilization statistics of FWCs from computer simulations and then perform optimization to allocate the FWCs. Therefore, our algorithms are widely applicable and they are not restricted to any particular model or assumption. We have conducted extensive computer simulations on regular and irregular networks under both uniform and nonuniform traffic. Compared with the best existing allocation, the results show that our algorithms can significantly reduce: (1) the overall blocking probability (i.e., better mean quality of service) and (2) the maximum of the blocking probabilities experienced at all the source nodes (i.e., better fairness). Equivalently, for a given performance requirement on blocking probability, our algorithms can significantly reduce the number of FWCs required.

This paper investigates the fault-diagnosis problem for all-optical wavelength-division-multiplexing (WDM) networks. A family of failure-localization algorithms that exploit the unique properties of all-optical networks is proposed. Optical probe signals are sequentially sent along a set of designed lightpaths, and the network state is inferred from the result of this set of end-to-end measurements. The design objective is to minimize the diagnosis effort (e.g., the average number of probes) to locate failures. By establishing a mathematical equivalence between the fault-diagnosis problem and the source-coding problem in information theory, we obtain a tight lower bound for the minimum average number of probes per edge (of the network modeled as a graph) as H/sub b/(p), the entropy of the individual edges. Using the rich set of results from coding theory to solve the fault-diagnosis problem, it is shown that the "2/sup m/-splitting" probing scheme is optimum for the special case of single failure over a linear network. A class of near-optimum run-length probing schemes that have low computation complexity is then developed. Analytical and numerical results suggest that the average number of probes per edge for the run-length probing scheme is uniformly bounded above by (1+/spl epsiv/)H/sub b/(p) and converges to the entropy lower bound as the failure probability decreases. From an information-theoretic perspective, it is shown that the run-length probing scheme outperforms the greedy probing scheme of the same computational complexity. The investigation reveals a guideline for efficient fault-diagnosis schemes: Each probe should provide approximately 1 bit of information, and the total number of probes required is approximately equal to the entropy of the state of the network. This result provides an insightful guideline to reduce the overhead cost of fault management for all-optical networks and can further the understanding of the relationship between information entropy and network management. Several practical issues are also addressed in the implementation of run-length probing schemes over all-optical WDM networks.