Lincong Zhang

Multi-path routing in Spatial Wireless Ad Hoc networks

In recent years, Spatial Wireless Ad Hoc (SWAH) networks constructed in the near spatial region by connecting various pieces of spatial and ground communication equipment have become the focus for developing future information networks. Due to their special characteristics, the traditional routing protocols in fixed networks and ad hoc networks cannot be used directly in SWAH networks. Therefore, the design of a special routing protocol for SWAH networks has become a challenge. In this paper, we propose a new Hybrid On-demand Distance Vector Multi-path (HODVM) routing protocol that divides the SWAH networks into backbone and non-backbone networks to perform static routing and dynamic routing, respectively. To provide load balancing, HODVM can adaptively establish and maintain multiple node-disjoint routes by multi-path routing. Simulation results show that, compared to traditional routing protocol, HODVM not only has better performance in terms of scalability and survivability but can also balance the network load well.

A new integrated energy-saving scheme in green Fiber-Wireless (FiWi) access network

Energy savings in Internet have been regarded as a significant technical issue for academic and industrial community. Particularly, access network accounts for more than 70% of the total energy consumption of Internet. As a promising access technique, Fiber-Wireless (FiWi) network not only enables the cost-effective broadband access, but also provides more opportunities for energy savings. Previous works mostly focused on the energy savings in the optical back-end of FiWi. Generally, they extended the Optical Network Unit (ONU) sleep mechanisms initially designed for Passive Optical Network (PON) to FiWi by combining with the wireless rerouting. However, most of these works left the energy savings in the wireless front-end untouched. In fact, when one or more ONUs in the network is/are sleeping, many wireless components remain idle or underutilized which cause a lot of energy waste. Motivated by this, we propose a new integrated Wireless-Optical Energy Savings (WOES) scheme for the comprehensive energy savings in FiWi. The WOES scheme consists of two interactive modules, Energy-Efficient ONU Management (EEOM) and Energy-Aware Topology Configuration (EATC). EEOM aims at the energy savings in the optical back-end by putting the low-load ONUs into sleep state. A pair of thresholds is introduced into EEOM to maintain the states of ONUs. As soon as ONUs states change, EATC will reconfigure the wireless topology by putting the idle Radio Interfaces (RIs) into standby state, thus minimizing the energy consumption of the wireless front-end. Simulation results show that the WOES scheme can reduce the energy consumption significantly with just a little performance degradation in network throughput and end-to-end delay.

Energy Saving Mechanism based on Sleep mode and Dynamic double-threshold link selection in EPON

The existing energy saving algorithms are implemented only with one kind of Passive Optical Network (PON). However, as far as Ethernet PON (EPON), good performances can not be reached simultaneously in both 10G-EPON and 1G-EPON. 10G-EPON can provide higher throughput and lower delay than 1G-EPON, but it consumes more energy. Therefore, to obtain trade-off performances, we propose a new Energy Saving Mechanism based on Sleep mode and Dynamic double-threshold link selection (ESM-SD) with the combination of 1G-EPON and 10G-EPON techniques. In ESM-SD, the downstream link can be switched between 1Gbps and 10Gbps according to dynamic double-threshold link selection. Hereby, ESM-SD can provide higher throughput and lower delay than 1G-EPON while consume less energy than 10G-EPON. To support ESM-SD, new structures for Optical Line Terminal (OLT) and Optical Network Unit (ONU) are introduced. Simulation results show that ESM-SD achieves better performances than the traditional schemes.

Game theory based inter-domain protection in multi-domain optical networks

This paper develops the multi-domain optical network model with considering multiple QoS parameters, present a game model to find the optimal solution, and propose an Inter-domain End-to-end Protection (IEP) that uses a Bacterial Colony Optimization (BCO) algorithm and a heuristic algorithm to solve survivability in intra-domain routing and inter-domain routing, respectively. Simulation results show that IEP performs better than traditional algorithm.

Energy-efficient rings mechanism for greening multisegment fiber-wireless access networks

Abstract. Through integrating advantages of optical and wireless communications, the Fiber-Wireless (FiWi) has become a promising solution for the “last-mile” broadband access. In particular, greening FiWi has attained extensive attention, because the access network is a main energy contributor in the whole infrastructure. However, prior solutions of greening FiWi shut down or sleep unused/minimally used optical network units for a single segment, where we deploy only one optical linear terminal. We propose a green mechanism referred to as energy-efficient ring (EER) for multisegment FiWi access networks. We utilize an integer linear programming model and a generic algorithm to generate clusters, each having the shortest distance of fully connected segments of its own. Leveraging the backtracking method for each cluster, we then connect segments through fiber links, and the shortest distance fiber ring is constructed. Finally, we sleep low load segments and forward affected traffic to other active segments on the same fiber ring by our sleeping scheme. Experimental results show that our EER mechanism significantly reduces the energy consumption at the slightly additional cost of deploying fiber links.

Optimizing backup resource configuration in survivable fiber-wireless access network considering failure probability

This paper focuses on the survivability of FiWi access network. A protection scheme is proposed to tolerate multiple-segments failure considering failure probability. Simulation results demonstrate that the proposed scheme is effective in optimizing backup resource.