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Fiber-Wireless (FiWi) access network is now becoming a promising architecture for access networks. Survivability is one of the key issues in the planning of FiWi access network because many high-rate traffic flows may be interrupted in case of a single fiber failure, which can cause a huge traffic loss. In addition, the users need ubiquitous broadband access that can be provided by FiWi access network. In this paper, we propose the protection approach called Maximum Covering Planning with Survivability (MCPS), including Integer Linear Programming (ILP) solution and heuristic solution, for the planning of survivable FiWi access network against single distribution fiber failure. The proposed approach aims at maximum coverage under the constraints of network connectivity. When a distribution fiber is broken, the interrupted Optical Network Unit (ONU) can transmit traffic to its backup ONU through the wireless paths between them. Simulation results show the network coverage of clients for different number of ONUs in different urban areas, and demonstrate the relationship between network coverage and the cost represented by the number of WiFi routers. [ABSTRACT FROM AUTHOR]

Abstract: Since optical network carries a lot of traffic, survivability is very important to ensure the service continuity against network failures. Recently, multicast services become more popular to meet the huge multimedia demand in network, so that multicast survivability in optical network has got more attention. However, multicast survivability may lead to more energy consumption due to more redundant backup resources allocated. Since greening network is particularly important with the energy crisis keeping growing, green multicast survivability in optical network is a challenging issue. This paper focuses on the green multicast grooming protection problem in optical network and designs two auxiliary graphs that includes a virtual topology graph and an integrated graph to address the survivable multicast grooming, routing and wavelength assignment. Based on the auxiliary graphs, this paper proposes an efficient heuristic called green multicast grooming algorithm based on spanning path dedicated protection (GMG-SPDP), in which the network reliability and the energy efficiency are jointly taken into account. Simulation results show that, compared to other algorithms, the proposed GMG-SPDP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy. [Copyright &y& Elsevier]

Abstract: Fiber-wireless (FiWi) access network is a promising access technology because it integrates the merits of optical and wireless access networks. In FiWi network, the placement of optical network units (ONUs) is one of the key issues for the network deployment since the ONU acts as the interface between wireless front-end and optical back-end. Some works have been carried out to investigate the ONU placement in FiWi. However, most of these works consider only the Internet traffic and ignore the effect of peer-to-peer (P2P) traffic on the ONU placement. Furthermore, all of these works remain untouched on the issue of load balancing among different ONUs. In this paper, we propose a novel ONU placement algorithm called load balanced ONU placement (LBOP) with the consideration of both Internet traffic and P2P traffic. According to the LBOP algorithm, with the objective of minimizing the number of ONUs, we first place the ONUs one-by-one in a greedy manner under the constraints of wireless hop number for both types of traffic. Then, for the purpose of load balancing, we implement the load transferring among different ONUs by coordinating the sets of their subordinate wireless routers. Simulation results demonstrate that the proposed LBOP algorithm is more effective in reducing the number of ONUs and achieving the load balancing than previous works. [Copyright &y& Elsevier]

Abstract: Saving the electrical requirements of network operators around the world makes power costs show a continuously decreasing trend. However, reducing the power costs is not only one way of gaining the marginal profit, a network operator also needs providing high-level quality of service (QoS), as well as employs effective strategies of pricing and hybrid grooming (i.e., integration of traffic grooming with an optical bypass) to make more users wish to pay the expense for their applications. In the final, users enjoy their services meanwhile operators obtain high profit in a power-efficient way, i.e., “double-win”. Accordingly, we propose the fast sub-optimal heuristics including Single-hop and Power-efficient Grooming algorithm based on Game theory (SPG2) as well as Multi-hop and Power-efficient Grooming algorithm based on Game theory (MPG2). Simulation results demonstrate that, compared with SPG2, MPG2 has the better comprehensive performance of both power efficiency and double-win between user and network operator in IP over WDM networks. [Copyright &y& Elsevier]

Traditional Wavelength-Division-Multiplexing (WDM) optical networks, which allocate spectrum resource in a fixed grid, may lead to inefficient resource utilization, low flexibility and high energy consumption. Therefore, by introducing the Orthogonal Frequency Division Multiplexing (OFDM) technology to the spectrum elastic optical networks could utilize spectrum resources efficiently. This paper established a power consumption model in spectrum elastic optical networks. Both dedicated and shared path protection were studied with static traffic demand under 6 different modulation modes. Considering the energy consumption of the network, a Routing and Modulation Level Spectrum Allocation (RMLSA) algorithm is proposed. In this algorithm, power saving can be achieved by dynamically adapting the number of bandwidth variable-transponders according to the chosen modulation level. Furthermore the paper proposed Spectrum Efficient RMLSA (SERMLSA) to make a trade-off between the energy consumption and the fragmentation. Based on the SERMLSA algorithm, we also proposed Allowing n fragments spectrum efficient RMLSA (AnSERMLSA) algorithm which allowed the fragments in certain limitation to save more energy. Simulation results showed that, in terms of energy saving and spectrum utilization, the proposed SERMLSA and AnSERMLSA heuristic algorithms reflected good performances in energy saving and defragmentation. [ABSTRACT FROM AUTHOR]

Abstract: In passive optical network (PON), the existing energy-saving algorithms are implemented only with one kind of PON. However, as far as Ethernet PON (EPON), good performances cannot be reached simultaneously in both 10G-EPON and 1G-EPON. Although 10G-EPON can provide higher throughput and lower delay than 1G-EPON, it consumes more energy. Currently, there are four types of optical network unit (ONU) sleep modes which are specified by ITU-T. If transmitter and receiver can be turned off independently without upstream traffic or downstream traffic, additional energy can be saved. Therefore, in this paper, to obtain high throughput and low delay with low energy consumption, we propose a new energy saving mechanism based on double-sleep-state and dynamic double-threshold receiver selection (EDDS) with the combination of 1G-EPON and 10G-EPON techniques. In EDDS, ONU's receiver not only can be switched between 1Gbps receiver and 10Gbps receiver according to the downstream traffic, but also can be put into sleep state independently when possible. Hereby, EDDS can provide higher throughput and lower delay than 1G-EPON while consume less energy than 10G-EPON. To support EDDS, new structures for optical line terminal (OLT) and ONU are introduced. Simulation results show that EDDS achieves better performances than the traditional schemes. [Copyright &y& Elsevier]