Optical Switching and Networking最新文献

Dynamic multiple multicasts widely exist in several applications of optical network-on-chip. However, there is no good solution for routing and wavelength assignment for multiple multicasts in the mesh-based network. This paper proposes a new routing strategy based on a modified artificial fish swarm algorithm. The modified artificial fish model can support unicast and multicast in the mesh-based network. The routing and wavelength assignment for multiple multicasts can be solved based on this model. Then, we design a layer-based algorithm to assign wavelength for multiple multicasts, which can utilize wavelength and area resources more effectively. Simulation results show that our scheme works better than the other tree-based schemes regarding average communication latency and power consumption. In general, our modified artificial fish swarm algorithm provides a universal platform to study different aspects of routing and wavelength assignment in mesh-based ONoC.

We revisit spectrum allocation (SA), a fundamental problem in optical network design, and we explain that it can be modeled as a permutation problem. This new model eliminates spectrum symmetry, a property that presents a significant challenge to conventional spectrum allocation solutions. Accordingly, we develop parameterized first-fit (PFF), a new symmetry-free heuristic for the SA problem that has several desirable features: it explores a pre-defined subset of the solution space whose size is tailored to the available computational budget; it constructs this subset by sampling from diverse areas of the solution space rather than from the neighborhood of an initial solution; it finds solutions by applying the well-known first-fit (FF) algorithm and thus it can be deployed readily; its execution can be easily parallelized; and it is effective and efficient in finding good quality solutions.

We consider a joint optimization problem of optical network resources and virtual network function (VNF) placement for efficient content distribution. Current content distribution networks (CDNs) are tightly coupled with network function virtualization (NFV) technologies. A virtual CDN (vCDN) has been intensively investigated to efficiently cope with unpredictable traffic demand. In vCDN, CDN functions are virtually provided as VNF, and we can provide sufficient flexibility regarding the usage of compute resources under traffic demand changes. For the cost-effective CDN services, we must reduce the redundant usage of network resources while improving the efficiency of compute resources. However, a conventional optimal VNF placement technique in vCDN was focused on the efficiency of compute resources, and this can lead to an increase in network cost. To address this issue, we formulate the optimization problem as mixed integer linear programming and then propose a heuristic algorithm called a light-weight VNF placement algorithm in vCDN (LP-vCDN) for reducing network cost while effectively utilizing compute resources. We conducted intensive numerical experiments and demonstrated that LP-vCDN always found solutions of sufficient quality with practical computational overhead.

Cloud computing and web applications have further highlighted the need for powerful data centers with large bandwidth and low power consumption. In order to provide such a large bandwidth, today's electronic data centers require high power levels. Furthermore, communications and devices are not always used to their full potential. Optical networks can be a proper option for data centers, as they can offer large and variable bandwidth with lower power consumption compared to their electronic counterparts. In this regard, a dynamic all-optical network architecture is proposed in this paper, with bandwidth reconfiguration capability and low latency to reduce energy consumption. This proposed architecture, called Flat Ball, offers dynamic bandwidth utilizing passive optical devices with low power consumption and latency. Under realistic data center traffic scenarios, the latency of this network is up to 50% lower than its electrical counterpart, while providing a much higher throughput and consuming up to 60% less power.

Light-Fidelity (LiFi) is quickly emerging as the next-generation communication technology thanks to its unique benefits, such as available spectrum, high data rates, low implementation costs, and inherent beamforming capabilities. As a consequence, it is endorsed by the scientific literature as an appealing innovation for disclosing disruptive services. The wavefront of LiFi technology is very wide: in this manuscript, we focus our attention on the interplay with the Internet of Things. Essentially, LiFi can assist the IoT in interconnecting a massive number of heterogeneous devices by addressing the current Radio Frequency spectrum bottleneck. Moreover, by investigating LiFi and IoT individually, several surveys and review papers testify to the noteworthiness of both technologies. However, to the best of the authors’ knowledge, a comprehensive investigation of contributions where both of them interplay is missing. To fill this gap, this survey provides a thorough investigation of all the research areas in which LiFi key features might enhance the upcoming IoT networks. The evaluation of existing literature on LiFi adopted in the IoT domain can be valuable in identifying missing gaps arising from the interaction of these two technologies, as well as proficiently pinpointing future research directions.

In this paper, a self-adaptive anti-misalignment model for transceivers in hybrid radio frequency (RF) communication and visible light communication (VLC) vehicle-to-vehicle (V2V) network is firstly proposed to solve the transceiver misalignment (TM) between vehicles in adjacent lanes caused by vehicle states' changes. By the information on roads and the state of vehicles, traffic scenarios are divided into three categories: the static traffic scenario, the low-speed traffic scenario and the high-speed traffic scenario. By the vehicle behavior characteristics, the relationship between TMs and vehicle states in different traffic scenarios is established. By the relationship, the self-adaptive anti-misalignment model for transceivers is constructed. By the model, the TM can be predicted and the communication mode can be selected. By simulation, the effectiveness of the model is demonstrated. The simulation results show that the model has comparative advantages of preventing the VLC links' interruption and reducing communication modes’ handover numbers in different traffic scenarios.

For the purpose of improving the resources utilization efficiency and decrease network redundancy of electric power communication network (EPCN), the paper explores using failure independent path protection preconfigured cycle (FIPP p-Cycle) to provide backup paths for electric communication service and presents a protection algorithm of enhanced FIPP p-Cycle with traffic grooming (EFIPP-TG). Firstly, the multiplexing conditions of FIPP p-Cycle are analyzed specifically, and we propose a FIPP p-Cycle multiplexing algorithm to improve the utilization efficiency of backup resources. Then segment protection algorithm for working path is designed to decrease service blocking ratio as much as possible. In addition, by taking advantage of traffic grooming strategy, the routing paths of services are optimized, yielding effective decrease of network blocking probability. Simulation results from different topologies demonstrate that compared with traditional FIPP p-Cycle scheme, other p-Cycle based protection algorithms and shared backup path protection algorithm, the proposed EFIPP-TG algorithm can significantly reduce the redundancy and blocking probability of networks, shorten the length of backup path and hence improve the reliability of service and performance of network survivability.

Radio frequency (RF) spectrum is highly occupied and adding further broadband channels to fulfill the exiting user requirements has become difficult. Optical free-space communication can be regarded a possible alternative as it offers several potential advantages such as reliable connectivity, secure link, higher data rates, and large bandwidth. Consequently, free-space optical (FSO) communication system which is the most dominant optical wireless technology has become more attractive in current era to deploy additional broadband channels, and it can support bandwidth-hungry services. FSO has appealing benefits such as easy deployment, inherited secure communication, higher data rate, non-interfering link, and licensed-free large spectrum. FSO communication links are also susceptible to several meteorological situations including smog, fog, scintillation, smoke, snow, and dust. A critical research question is to ensure connectivity under these adverse circumstances. FSO communication is severally hampered by link attenuation, atmospheric turbulence, and line-of-sight (LOS) demands. To overcome these challenges, relay nodes can be employed to improve coverage area and error rate of FSO communication system. However, relay nodes cannot overcome pointing errors in FSO communication due to various critical factors such as building sway. To enhance the availability of FSO systems, a redundant backup RF link to form a hybrid network is a viable solution. The coexistence of both RF and optical system is proposed to tackle challenges as mentioned before and attain benefits of both spectrums. A hybrid FSO/RF technology is promising as it can substantially enhance the availability and reliability than individual channels and offers unique solution to high-throughput wireless connectivity, comparable data rates, and insensitivity to weather conditions. This hybridization approach can help both channels to jointly recover the deficiencies of each technology and secure efficient data transmission with highly variable channel conditions. The immediate switching in hybrid FSO/RF systems can enable suboptimal usage of FSO network. In this study, we examine switching techniques, routing protocols, channel models, and modulation schemes. We outline several projects discussed in literature and examine various application scenarios. Finally, we discuss potential challenges, physical layer security issues and associated practical solutions.

In control-plane of optical packet forwarding engines (OPFEs), the group-membership query algorithm determines the egress through which a packet should be forwarded. To implement a high-performance multicast-enabled switch/router, a super-fast group-membership query algorithm is the key element within the PFEs which require the following essential properties: high link-bandwidth, high port-density, high forwarding speed, high scalability, and affordable cost. Current group-membership query approaches such as Bloom filter (BF) and Scalar-Pair Vectors Routing and Forwarding (SVRF) still suffer from serious weaknesses in terms of the space/time inefficiency, false-positive error, and low maintainability, etc. To accommodate these weaknesses, we propose an improved forwarding scheme–M-way Scaler-matrix and Vectors Routing and Forwarding (M-way SVRF) by re-examining the idea of the original SVRF. The M-way SVRF divides a ρ-bit port identifier into M-sub-blocks in the memory unit, thus element's keys belonging to distinct sub-blocks are able to reuse relatively smaller identical prime keys. Compared to previous works, simulation results show that the membership queries can be partitioned to leverage task parallelism, and better performance in the aspects of memory consumption and computational complexity, especially when the port-density of optical PFE is sufficiently high.