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Traditionally, a packet with errors, either due to channel noise or collisions, is discarded and needs to be retransmitted, leading to performance losses. Hybrid Automatic Retransmission reQuest (H-ARQ) and time diversity multipacket reception approaches, such as Network Diversity Multiple Access(NDMA), improve the system performance by requesting additional retransmissions and combining all the signals...
Higher-Vth devices in the cross-coupled latches and the write access transistors, and lower-Vth devices in the read ports are preferred for reducing leakage current without sacrificing performance. However, at ultra-low supply voltage levels, higher-Vth devices can retard or nullify energy efficiency due to substantially slower write speed than read. This paper presents energy efficiency maximization...
Wildlife sounds provide relevant information for non-intrusive environmental monitoring when Wireless Sensor Networks (WSNs) are used. Thus, collecting such audio data, while maximizing the network lifetime, is a key challenge for WSNs. In this work, we propose a methodology that applies Compressive Sensing (CS) aiming at collecting as little data as possible to allow the signal reconstruction, so...
The hidden terminal problem in wireless sensor network (WSN) is one of the main causes of collision. Even though RTS/CTS handshaking has been implemented in CSMA/CA standard to alleviate the problem, it does not solve the collision completely. Moreover, it induces an issue called false blocking problem. Unaware of a busy status of a hidden receiver, adjacent nodes which can be potential senders will...
In this paper, a new recursive multibit recoding multiplication algorithm is introduced. It provides a general space-time partitioning of the multiplication problem that not only enables a drastic reduction of the number of partial products (N/r), but also eliminates the need of pre-computing odd multiples of the multiplicand in higher radix (r≥3) multiplication. Based on a mathematical proof that...
Wireless traffic that is destined for a certain device in a network, can be exploited in order to minimize the availability and delay trade-offs, and mitigate the Energy consumption. The Energy Conservation (EC) mechanism can be node-centric by considering the traversed nodal traffic in order to prolong the network lifetime. This work describes a quantitative traffic-based approach where a clustered...
Mobility management in IEEE 802.15.4/ZigBee networks is not efficiently handled. This paper presents an enhanced approach for mobility management of end devices in IEEE 802.15.4/ZigBee cluster tree network related to a backbone network. This approach anticipates link disruption and does not require scanning neighbor cells. It is based on the link quality indicator (LQI) and uses a speculative algorithm...
Switching the operating state on machines is probably the simpler way to reduce the energy consumption of otherwise non energy-aware devices. Indeed, many energy-aware systems allow two states of operation: a low power idle (LPI) mode, in which the system is unable to process data, and a fully working mode. For networking equipment, packet coalescing is the best known algorithm for managing the LPI...
A large part of power dissipation in a system is generated by I/O devices. Increasingly these devices provide power saving mechanisms, inter alia to enhance battery life. While I/O device scheduling has been studied in the past for real-time systems, the use of energy resources by these scheduling algorithms may be improved. These approaches are crafted considering a very large overhead of device...
In hierarchical networks, nodes are separated to play different roles such as CHs and cluster members. Each CH collects data from the cluster members within its cluster, aggregates the data and then transmits the data to the sink. Each algorithm that is used for packet routing in quality of service (QoS) based applications should be able to establish a tradeoffs between end to end delay parameter...
For smaller scale wireless sensor networks (WSN) it has been clearly shown that a single mobile sink can be very beneficial with respect to the network lifetime. Yet, how to plan the trajectories of many mobile sinks in very large WSNs in order to simultaneously achieve lifetime and delay goals has not been treated so far. In this paper, we delve into this difficult problem and propose a heuristic...
Wireless sensor networks (WSN) are one of most interesting emerging technologies. WSN can be used to perform monitoring, surveillance, sensing and measuring operations. In order to further increase these applications, minimizing energy consumption is one of the most critical issues. Therefore, accurate energy model is required for the evaluation of wireless sensor networks performance. In this paper,...
The wireless sensor network (WSN) is one new hot spot for both research and industry. However, the energy problem has been becoming a challenge in practical applications for WSN because the sensor nodes are supplied with energy by batteries which are difficult to be recharged and replaced. So many researches are taken on reducing the energy consumption of WSN nodes. Medium Access Control (MAC) layer...
In this paper, we propose several design approaches to extend useful voltage scaling (i.e. voltage scaling with net energy savings) beyond the conventional limit, which is imposed by the rapid increase of leakage energy overhead in ultra low voltage regimes. We are able to achieve such extra voltage scaling and thus energy savings without compromising performance and variability through minimizing...
In this paper we investigate the network lifetime maximization problem in a delay-tolerant wireless sensor network with a mobile sink by exploiting a nontrivial tradeoff between the network lifetime and the data delivery delay. We formulate the problem as a joint optimization problem that consists of finding a trajectory for the mobile sink and designing an energy-efficient routing protocol to route...
Energy consumption in wireless sensor networks (WSN) was always a basic constraint to respect. But, with the appearance of Wireless Multimedia Sensor Networks (WMSN), another basic constraint comes from added, which is the traffic performance in terms of delay, throughput, and Packet Delivery Rate (PDR). The choice of channel access method can help us to better respond the two constraints in WMSN...
Wireless networks are characterized by a dynamic topology triggered by the nodes mobility. Thus, the wireless multi-hops connection and the channel do not have a determinist behaviour such as: interference or multiple paths. Moreover, the nodes' invisibility makes the wireless channel difficult to detect. This wireless networks' behaviour should be scrutinized. In our study, we mainly focus on radio...
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...
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...
In Wireless Sensor Networks (WSNs), congestion can cause a number of problems including packet loss, lower throughput and poor energy efficiency. These problems can potentially result in reduced deployment lifetime and under-performing applications. This has led to several proposals for congestion control (CC) mechanisms for sensor networks. Furthermore, the WSN research community has made significant...
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