The smart grid concept continues to evolve and various methods have been developed in order to enhance the energy efficiency of the electricity infrastructure. Demand Response (DR) is considered as the most cost-effective and reliable solution for the smoothing of the demand curve, when the system is under stress. DR refers to a procedure that is applied to motivate changes in the customers' power consumption habits, in response to incentives regarding the electricity prices. In this paper, we provide a comprehensive review of various DR schemes and programs, based on the motivations offered to the consumers in order to participate in the program. We classify the proposed DR schemes according to their control mechanism, to the motivations offered to reduce the power consumption and to the DR decision variable. We also present various optimization models for the optimal control of the DR strategies that have been proposed so far. These models are also categorized, based on the target of the optimization procedure. The key aspects that should be considered in the optimization problem are the system's constraints and the computational complexity of the applied optimization algorithm.

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International audienceIn this Letter, a low-complexity Euclidean distance-based method for antenna subset selection in Spatial Modulation systems is presented. The proposed method avoids the high complexity of both the optimal exhaustive search and of a recently proposed Euclidean distance-based algorithm for performing the selection. Moreover, as the number of receive antennas increases and for practical signal-to-noise ratio (SNR) values, it offers better error performance than the conventional transmit antenna selection (TAS) algorithm. In addition, the benefits of the proposed selection scheme, as the number of receive antennas increases, are further substantiated by comparing its relative energy gain over the TAS method for a target uncoded Symbol Error Rate (SER

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The persistent relay carrier sensing multiple access (PRCSMA) protocol is presented in this paper as a novel medium access control (MAC) protocol that allows for the execution of a distributed cooperative automatic retransmission request (ARQ) scheme in IEEE 802.11 wireless networks. The underlying idea of the PRCSMA protocol is to modify the basic rules of the IEEE 802.11 MAC protocol to execute a distributed cooperative ARQ scheme in wireless networks in order to enhance their performance and to extend coverage. A closed formulation of the distributed cooperative ARQ average packet transmission delay in a saturated network is derived in the paper. The analytical equations are then used to evaluate the performance of the protocol under different network configurations. Both the accuracy of the analysis and the performance evaluation of the protocol are supported and validated through computer simulations.

Abstract-In this letter, we study the performance of Network Coding (NC)-aided cooperative communications in large scale networks, where the relays are able to harvest energy emitted by wireless transmissions. In particular, we derive theoretical expressions for key network performance metrics, i.e., the probability of successful data exchange and the network lifetime gain. The proposed analytical expressions are verified via extensive Monte Carlo simulations, demonstrating the potential benefits of the energy harvested by the wireless transmissions.

Abstract-Macrocells are expected to be densely overlaid by small cells (SCs) to meet the increasing capacity demands. Due to their dense deployment, some SCs will not be connected directly to the core network and thus they may forward their traffic to the neighboring SCs until they reach it, thereby forming a multi-hop backhaul (BH) network. This is a promising solution, since the expected short length of BH links enables the use of millimeter wave (mmWave) frequencies to provide high capacity BH. In this context, user association becomes challenging due to the multihop BH architecture and therefore new optimal solutions should be developed. Thus, in this paper, we study the user association problem aiming at the joint maximization of network energy and spectrum efficiency, without compromising the user quality of service. The problem is formulated as an ε-constraint problem, which considers the transmit energy consumption both in the access network, i.e., the links between the users and their serving cells, and the BH links. The optimal Pareto front solutions of the problem are analytically derived for different BH technologies and insights are gained into the energy and spectrum efficiency trade-off. The proposed optimal solutions, despite their high complexity, can be used as a benchmark for the performance evaluation of user association algorithms. We also propose a heuristic algorithm, which is compared with reference solutions under different traffic distribution scenarios and BH technologies. Our results motivate the use of mmWave BH, while the proposed algorithm is shown to achieve near-optimal performance.