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Until recently, link adaptation and resource allocation for communication system relied extensively on the spectral efficiency as an optimization criterion. With the emergence of the energy efficiency (EE) as a key system design criterion, resource allocation based on EE is becoming of great interest. In this paper, we propose an optimal EE-based resource allocation method for the scalar broadcast...
We analyze the energy efficiency of reactive and proactive relay selection algorithms under the incremental decode-and-forward protocol. By taking into account the consumption of the RF circuitry, the transmit power, and a nonlinear model for the battery, we show that a large number of available relays can actually compromise the energy efficiency of the system. Our results show that, depending on...
In this paper, we propose a new definition of energy efficiency with respect to a given target packet error rate (PER). It is shown that some previous reported definitions are actually special cases of our definition. Consequently we use the definition to analyze the energy efficiency of Multilevel quadrature amplitude modulation (MQAM) and find that for a specific transmission there exists an energy...
Due to the potential detection error caused by information loss in sampling process, collaborative scheme is especially important for compressed sensing-based spectrum detection to improve the detection accuracy. In this paper, a novel energy-efficient low-complexity collaborative scheme is proposed for cognitive radio networks. In the proposed scheme, based on the prediction results of signal sparsity...
Implementing incremental relaying in a practical system is not a trivial task because it requires the destination node to provide feedback on success or failure of a transmission. In practice, the feedback may be affected by propagation impairments and collisions. In this case, the relay and the source should coordinate among themselves in the absence of perfect feedback information such that packet...
Minimizing energy consumption is becoming more and more crucial in today's mobile terminals communications. Reducing its use pass necessarily by exploiting low power design techniques and by adopting novel energy-aware applications and protocols. The focus in this paper mainly concerns the Voice over IP over Wireless Local Area Network (VoWLAN) application, which is beyond doubt the most popular application...
The proliferation of wireless broadband usage over the last decade has led to the development and deployment of multiple broadband wireless radio access technologies (RATs) such as EVDO, WiMAX, HSPA and LTE. To support the ever-increasing wireless traffic demand, researchers have worked on the concept of an integrated heterogeneous wireless environment that encompasses several of these RATs which...
One of the most rapidly expanding areas, nowadays, in networking systems is the Wireless Sensor Network (WSN). Typically WSNs rely on multi-hop routing protocols which must be able to establish communication among nodes and guarantee packet deliveries. In this paper, we present a novel approach for the implementation of the WSN routing protocols, which takes advantage of modern FPGAs in order to provide...
Efficient energy consumption is a challenging problem in wireless sensor networks (WSNs) and closely related to extending network lifetime. The usual way of tackling this issue for topologies with fixed link weight and fixed sink location, has been shown to be severely affected by the energy hole problem. In this paper, the energy consumption problem is initially studied for WSNs with fixed sink assignment...
In this paper we propose an energy efficient image transmission strategy for wireless sensor networks, which combines wavelet-based image decomposition and cooperative communication. In the proposed scheme we use selective decode-and-forward (SDF) cooperation, so that a relay node collaborates with the source by forwarding only a lower-resolution version of the original image, obtained via discrete...
A principal issue for wireless sensor networks is energy efficiency, which is necessary for prolonging applications to track continuous object, such as wild fire and poison gas. Selective wakeup approach is an effective way to save energy in such networks. However, most previous studies on selective wakeup schemes have concentrated on individual objects, such as intruders and tanks, and they cannot...
Providing an energy-efficient communication scheme is highly desirable in Wireless Sensor Networks (WSNs), however this is often constrained by the processing and energy limitations of the wireless nodes. In this paper, we propose the use of a Turbo Code scheme to increase the robustness and energy efficiency of the communication between end nodes and base stations in single-hop topologies. Using...
As wireless communications experience tremendous growth, energy consumption is becoming a crucial problem in the wireless industry. Energy saving mechanisms are important for supporting the mobility and extending the battery life of a user equipment, reducing the operation costs of a network operator, enhancing corporate image of operators and vendors alike, and providing a lower total energy consumption...
This work addresses the problem of optimized content distribution over wireless networks with cooperation among mobile terminals. The mobile terminals are optimally divided into groups where each group internally cooperates by downloading and exchanging a common content from the base station in order to minimize the total energy consumed by the mobile terminals. We assume unicasting transmissions...
An approach advocated in the recent literature for reducing energy consumption in cellular networks is to put base stations to sleep when traffic loads are low. However, several practical considerations are ignored in these studies. In this paper, we aim to raise questions on the feasibility and benefits of base station sleeping. Specifically we analyze the interference and capacity of a coverage-based...
Using the technology of wireless energy transfer, the paper proposes Qi-ferry which physically carries energy, roves a wireless sensor network, and wirelessly charges sensor nodes to extend their lifetime. To optimize the usage of the entire energy reserve on a Qi-ferry, both the movement of the Qi-ferry itself and its wireless charging of sensor nodes share the same pool of battery energy reserve,...
Relay nodes (RN) have been suggested to be placed near the edge of a cellular network in order to improve link qualities of cell edge user equipments (UEs). Compared to conventional homogeneous networks, system performance for the relay-enhanced network can be significantly degraded if handovers between the RNs and evolved node base-station (eNB) are not correctly and immediately determined by the...
Probabilistic forwarding methods have been exploited in opportunistic networks to reduce the overhead of epidemic routing. However, most existing methods make all the nodes forward messages with the same probability (i.e., equal scheme), which causes the energy unbalance of nodes. To guarantee the energy balance of nodes and prolong the network lifetime, we design a differentiated scheme, i.e., different...
This paper studies the electricity consumption of mobile phone chargers. The charger's electricity consumption varies depending on its state. We measured the electricity consumption of various phone and charger models in different states. We also did panel studies on the recharging behavior of smartphone users. Based on these and other sources, we are able to estimate mobile phone recharging electricity...
The widespread deployment of varying networking technologies, coupled with the exponential increase in end-user data demand, have all led to the proliferation of multi-homed or multi-interface enabled devices. To date, these interfaces are mainly utilized one at a time based on network availability, cost, and user-choice. Researchers have recently focused on leveraging these interfaces simultaneously...
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