Optical Switching and Networking最新文献

As Ethernet has a large bandwidth capacity, it is commonly proposed as a backbone for future intra-vehicle networks. However, satisfying the severe hardware reliability requirements of intra-vehicle networks while providing high-bandwidth and low latency by Ethernet may be costly. As a solution, we propose a novel optical intra-vehicle backbone network architecture that may have a lower cost and higher reliability in terms of hardware when compared to Ethernet. However, unlike traditional optical Ethernet architectures, only a single master node has transmitter laser diodes in the backbone of our architecture, so the gateway nodes cannot generate and send packets to the backbone links directly. As the gateways cannot inform the master node and request a slot when they have a new packet to send, a slot scheduling algorithm with polling is necessary to detect and transfer the new packets in the gateways, which may cause higher transmission delays compared to Ethernet. In this paper, we present our optical intra-vehicle backbone network architecture and propose two slot scheduling algorithms. We show that using a dynamic slot scheduling algorithm decreases packet delays when compared to fixed periodic slot scheduling in our architecture. We also evaluate the total delays including traffic shaping and processing delays in an optical TSN Ethernet backbone architecture as a reference. We show that the extra delays due to slot scheduling in our architecture may be negligibly low when compared with traffic shaping and processing delays.

Elastic optical networks (EONs) have been introduced to meet the demands of the rapidly growing Internet. These networks can efficiently keep up with the emerging bandwidth-hungry and highly dynamic services, and can support multicast services using techniques like the path, tree or subtree methods. A multicast wavelength-space-wavelength (M-WSW) network is a switching node architecture for EONs, which adopts the subtree method to support multicast connections. An M-WSW network consists of three node stages in which wavelength, space and wavelength switches are used, respectively. A nonblocking M-WSW network guarantees that any connection between a free input and a free output can always be realized, and studying the nonblockingness of a network has attracted much attention from researchers. Sufficient conditions, in terms of the number of middle space switches, for an M-WSW network to be strict-sense nonblocking (SNB) or wide-sense nonblocking (WSNB) were examined in an earlier study. It is known that SNB networks usually incur a higher hardware cost, for instance, the number of middle space switches, compared to WSNB, rearrangeably nonblocking (RNB), or repackably nonblocking (RPNB) networks. This paper studies the rearrangeability and repackability of M-WSW networks, and derives the sufficient and necessary conditions for an M-WSW network to be RNB (or RPNB). The results show that the derived sufficient conditions for being RNB (or RPNB) require significantly fewer middle switches for SNB and WSNB networks, and the RPNB results require fewer middle switches than those for RNB in most cases.

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.