In this paper, we optimize the energy efficiency of device-to-multi-device (D2MD) communications. While point-to-point has been extensively studied to improve the spectral efficiency in cellular networks, the introduction of multicast communications brings, in addition, the possibility of reusing the spectrum resources also inside the groups. We formulate the energy efficiency problem in this context, and show that a decomposition approach which first uses matching theory to allocate the channels to each group, and then optimizes to find the unique transmission power vectors in each group gives good performance results for the optimization both of the system’s energy efficiency and of the max-min individual energy efficiency. This is achieved for a desired minimum transmission rate. Numerical results are presented to confirm the usefulness of the proposed framework for optimizing the planning and deployment of D2MD networks with energy efficiency as a primary performance goal.
En IEEE Transactions Communications,
Frame coalescing is one of the most efficient techniques to manage the low power idle (LPI) mode supported by Energy Efficient Ethernet (EEE) interfaces. This technique enables EEE interfaces to remain in the LPI mode for a certain amount of time upon the arrival of the first frame (time-based coalescing) or until a predefined amount of traffic accumulates in the transmission buffer (size-based coalescing). This paper provides new insights on the practical efficiency limits of both coalescing techniques. In particular, we derive the fundamental limits on the maximum energy savings considering a target average frame delay. Additionally, we present new open-loop adaptive variants of both time-based and size-based coalescing techniques. These proposals dynamically adjust the length of the sleeping periods in accordance with actual traffic conditions to reduce energy consumption while keeping the average delay near a predefined value simultaneously. Analytical and simulation results show that the energy consumption of both proposals is comparable to the fundamental limits. Consequently, we recommend the usage of the time-based algorithm in most scenarios because of its simplicity as well as its ability to bound the maximum frame delay at the same time.
En IEEE Transactions on Green Communications and Networking,
Both economic and environmental costs are driving much research in the area of energy efficiency of networking equipment. This research has produced a great amount of proposals. However, the majority of them remain unimplemented due to the lack of flexibility of current hardware devices and a certain lack of enthusiasm from commercial vendors. At the same time, Software-Defined Networking (SDN) has allowed customers to control switching decisions with a flexibility and precision previously unheard of. This paper explores the potential convergence between the two aforementioned trends and presents a promising power saving algorithm that can be implemented using standard SDN capabilities of current switches, reducing operation costs on both data centers and wired access networks. In particular, we focus on minimizing the energy consumption in bundles of Energy Efficient Ethernet links leveraging SDN. For this, we build on an existing theoretical algorithm and adapt it for implementing with an SDN solution. We study several approaches and compare the resulting algorithms not only according to their energy eficiency, but also taking into account additional QoS metrics. The results show that the resulting algorithm is able to closely match the theoretical results, even when taking into account the requirements of delay sensitive traffic.
In Sensors, 2018,
Energy efficiency of cellular networks can be greatly improve if base stations (BSs) can be put into a low power operation mode during low load periods. In this paper, we present a new dynamic scheme to manage the sleep mode of energy-aware BSs that can be autonomously governed. This kind of BSs, such as those operating in heterogeneous or hyper-cellular networks, can be put to sleep without causing undesired coverage holes, thus preserving the cellular service over the whole coverage area. With the proposed mechanism, energy-aware BSs enter the sleep mode as soon as they have no traffic to send and then apply a coalescing algorithm that dynamically adjusts the length of the sleeping periods to maximize the energy savings while maintaining the average service delay around a target value at the same time.
In Journal of Network and Computer Applications,
The energy demands of Ethernet links have been an active focus of research in the recent years. This work has enabled a new generation of energy-efficient Ethernet (EEE) interfaces able to adapt their power consumption to the actual traffic demands, thus yielding significant energy savings. With the energy consumption of single network connections being a olved problem, in this paper, we focus on the energy demands of linkaggregates that are commonly used to increase the capacity of a network connection. We build on known energy models of single EEE links to derive the energy demands of the whole aggregate as a function on how the traffic load is spread among its powered links. We then provide a practical method to share the load that minimizes overall energy consumption with controlled packet delay and prove that it is valid for a wide range of EEE links. Finally, we validate our method with both synthetic and real traffic traces captured inInternet backbones.
In IEEE Systems Journal,
Networking operational costs and environmental concerns have lately driven the quest for energy efficient equipment. In wired networks, energy efficient Ethernet (EEE) interfaces can greatly reduce power demands when compared to regular Ethernet interfaces. Their power saving capabilities have been studied and modeled in many research articles in the last few years, together with their effects on traffic delay. However, to this date, all articles have considered them in isolation instead of as part of a network of EEE interfaces. In this paper we develop a model for the traffic delay on a network of EEE interfaces. We prove that, whatever the network topology, the per interface delay increment due to the power savings capabilities is bounded and, in most scenarios, negligible. This confirms that EEE interfaces can be used in all but the most delay constrained scenarios to save considerable amounts of power.
In IEEE Communications Letters,
This paper presents a new frame coalescing mechanism that dynamically adjusts the coalescing queue threshold in order to minimize the energy consumption of dual-mode EEE interfaces and maintains, at the same time, the average frame delay close to a target value.
In IEEE Trans. Commun.,
This paper presents a promising mechanism that reduces energy consumption of user equipments using the DRX mechanism while simultaneously maintaining average packet delay around a desired target. In addition, our proposal is able to achieve significant power savings without either increasing signaling overhead or requiring any changes to deployed wireless protocols.
In IEEE J. Sel. Areas Commun.,
Rising energy consumption of IT infrastructure concerns have spurred the development of more power efficient networking equipment and algorithms. When old equipment just drew an almost constant amount of power regardless of the traffic load, there were some efforts to minimize the total energy usage by modifying routing decisions to aggregate traffic in a minimal set of links, creating the opportunity to power off some unused equipment during low traffic periods. New equipment, with power profile functions depending on the offered load, presents new challenges for optimal routing. The goal now is not just to power some links down, but to aggregate and/or spread the traffic so that devices operate in their sweet spot in regards to network usage. In this paper we present an algorithm that, making use of the ant colonization algorithm, computes, in a decentralized manner, the routing tables so as to minimize global energy consumption. Moreover, the resulting algorithm is also able to track changes in the offered loadand react to them in real time.
In Journal of Network and Computer Applications,
This paper evaluates through simulation the potential power savings that can be obtained in ONUs using the low power mode known as doze mode. In particular, the impact of the DBA algorithm and the doze mode governor on both energy efficiency and frame delay are analyzed.
In Journal of Lightwave Technology,
This paper provides a general GI/G/1 model for the energy consumption and the traffic delay obtained with a 10 Gb/s EEE interface using both frame and burst transmission algorithms. Specializations of the general model for Poisson and deterministic traffic are also provided.
In IEEE Trans. Commun.,
This paper provides mathematical models for the expected energy savings and the average packet delay obtained in EEE interfaces using the most well known sleeping algorithms. These models are then used to derive the optimum configuration parameters for the sleeping algorithms given some efficiency constraints.
In Computer Networks,
This paper provides an accurate analytical model for the power savings achievable in EEE devices using the burst transmission algorithm to govern the low power mode.
In IEEE Commun. Lett.,
Traditional TCP-Reno like congestion control protocols exhibit poor performance when deployed in fast or very large network paths. Delay based congestion avoidance mechanisms (DCA), like FAST-TCP, get much higher performance, in the same circumstances. However, when mixed with TCP-Reno or alike traffic they are unable to attain their fair share of bandwidth. In this paper we present a new mechanism that can indirectly detect the present of non DCA-friendly traffic that can be used by new DCA algorithms to auto-tune themselves with more aggressive parameters to achieve their fair share.
In NET COOP’ 2008,
Delay-based congestion control algorithms provide higher throughput and stability than traditional loss-based AIMD algorithms, but they are inherently unfair against older connections when the queuing and the propagation delay cannot be measured accurately and independently. This paper presents a novel measurement algorithm whereby fairness between old and new connections is preserved. The algorithm does not modify the dynamics of congestion control, and runs entirely in the server host using locally available information.
In IEEE Communications Letters,