The main advantage of multilayer automatically switched IP-over-MPLS-over-optical networks is their ability and their flexibility to adapt to the variations of the offered traffic. Multilayer traffic engineering mechanisms exploit this characteristic and perform traditional rerouting enriched with online IP logical topology reconfiguration. These mechanisms aim at optimizing resource usage and maximizing QoS, e.g. in terms of bandwidth, throughput and delay. Recently except from performance, energy efficiency in backbone core networks has gained much attention. In this article, we will examine how multilayer traffic engineering techniques can help to increase energy savings and minimize energy consumption. As we will present the simultaneous optimization of routing and minimization of the number of active network elements leads to significant energy savings. We will propose an adaptive algorithm for IP/MPLS/WDM with traffic grooming networks, which will aggregate traffic flows in the same LSPs and consequently in the same optical wavelengths. Additionally, this algorithm has the objective to reduce energy by switching off unused router line cards. In this way routing is optimized and the topology of IP layer is adapted to the variations of traffic in network. To achieve this, LSPs (links and optical channels) must be recomputed every time a new traffic flow enters network, using a specific cost function to compute link and channels weights according to their current availability.

Keywords: multilayer traffic engineering, traffic grooming, energy efficiency, load balancing

 One of the targets of Green Information and Communication Technology (ICT) is to reduce the energy consumption of ICT itself. This paper provides a tutorial on a new energy reduction approach – self-organization aided network sharing, which exploits the concept of cooperation and adaptation in the cellular system level. Detail reviews from different perspectives including the academic literature, the existing standard, etc. are provided. Moreover, a simply example with simulation results is provided to demonstrate the energy efficiency of the proposed scheme.

Keywords: network sharing, self-organization, energy efficiency, LTEA

  One of the main challenges of the arising wireless world is to support a wide set of QoS-demanding services. However, the solutions that will be considered should not only take into consideration the optimization of the network performance, but should also be energy efficient both for the operator and the end-user. This paper presents the concept of Opportunistic Networks (ONs) as an energy efficient method to exploit wireless networks. The cases studied in this work comprise a macro base station and femtocells. The proposed solution will offload a proportion of the traffic of the base station to the femtocells, through the creation of an ON. Therefore, the base station will consume less energy since terminals will be rerouted to the femtocells. In addition, the femto-terminals will operate to lower power levels leading to battery savings. Results from simulations are provided to confirm the proposed solution.

Keywords: opportunistic networks, capacity extension, future internet, femtocells, energy consumption