Results 1 - 10
of
26
Energy conservation in wireless sensor networks: A survey
"... In the last years, wireless sensor networks (WSNs) have gained increasing attention from both the research community and actual users. As sensor nodes are generally battery-powered devices, the critical aspects to face concern how to reduce the energy consumption of nodes, so that the network lifeti ..."
Abstract
-
Cited by 227 (11 self)
- Add to MetaCart
In the last years, wireless sensor networks (WSNs) have gained increasing attention from both the research community and actual users. As sensor nodes are generally battery-powered devices, the critical aspects to face concern how to reduce the energy consumption of nodes, so that the network lifetime can be extended to reasonable times. In this paper we first break down the energy consumption for the components of a typical sensor node, and discuss the main directions to energy conservation in WSNs. Then, we present a systematic and comprehensive taxonomy of the energy conservation schemes, which are subsequently discussed in depth. Special attention has been devoted to promising solutions which have not yet obtained a wide attention in the literature, such as techniques for energy efficient data acquisition. Finally we conclude the paper with insights for research directions about energy conservation in WSNs.
Exploiting Decentralized Channel State Information for Random Access
, 2002
"... We study the use of channel state information for random access in fading channels. Traditionally, random access protocols have been designed by assuming simple models for the physical layer where all users are symmetric and there is no notion of channel state. We introduce a reception model that ta ..."
Abstract
-
Cited by 82 (18 self)
- Add to MetaCart
(Show Context)
We study the use of channel state information for random access in fading channels. Traditionally, random access protocols have been designed by assuming simple models for the physical layer where all users are symmetric and there is no notion of channel state. We introduce a reception model that takes into account the channel states of various users. Under the assumption that each user has access to his channel state information (CSI), we propose a variant of Slotted ALOHA protocol for medium access control, where the transmission probability is allowed to be a function of the CSL The function is called the transmission control scheme. Assuming the finite user infinite buffer model we derive expressions for the maximum stable throughput of the system. We introduce the notion of asymptotic stable throughput (AST) that is the maximum stable throughput as the number of users goes to infinity. We consider two types of transmission control namely population independent transmission control (PITC) where the transmission control is not a function of the size of the network and population dependent transmission control where the transmission control is a function of the size of the network. We obtain expressions for the AST achievable with PITC. For population dependent transmission control, we introduce a particular transmission control that can potentially lead to significant gains in AST. For both PITC and PDTC, we show that the effect of transmission control is equivalent to changing the probability distribution of the channel state. The theory is then applied to CDMA networks with Linear Minimum Mean Square Error (LMMSE) receivers and Matched Filters (MF) to illustrate the effectiveness of utilizing channel state. It is shown that through the use of channel state, with an...
Data collection in wireless sensor networks with mobile elements: A survey
- ACM Trans. Sensor Networks
"... Wireless sensor networks (WSNs) have emerged as an effective solution for a wide range of applications. Most of the traditional WSN architectures consist of static nodes which are densely deployed over a sensing area. Recently, several WSN architectures based on mobile elements (MEs) have been propo ..."
Abstract
-
Cited by 34 (4 self)
- Add to MetaCart
Wireless sensor networks (WSNs) have emerged as an effective solution for a wide range of applications. Most of the traditional WSN architectures consist of static nodes which are densely deployed over a sensing area. Recently, several WSN architectures based on mobile elements (MEs) have been proposed. Most of them exploit mobility to address the problem of data collection in WSNs. In this paper we first define WSNs with MEs and provide a comprehensive taxonomy of their architectures, based on the role of the MEs. Then, we present an overview of the data collection process in such scenario, and identify the corresponding issues and challenges. On the basis of these issues, we provide an extensive survey of the related literature. Finally, we compare the underlying approaches and solutions, with hints to open problems and future research directions.
Transmission scheduling for optimizing sensor network lifetime: A stochastic shortest path approach
- Computer Engineering, University of California, Davis. Her
, 2006
"... We present transmission scheduling algorithms for maximizing the lifetime of a sensor network. In each data collection, only one group of sensors are scheduled to transmit their measurements directly to an access point (AP) through a fading channel, causing a reduction in battery energy levels of t ..."
Abstract
-
Cited by 19 (3 self)
- Add to MetaCart
(Show Context)
We present transmission scheduling algorithms for maximizing the lifetime of a sensor network. In each data collection, only one group of sensors are scheduled to transmit their measurements directly to an access point (AP) through a fading channel, causing a reduction in battery energy levels of these sensors. We formulate the problem of dynamically choosing which group of sensors should communicate with the AP to maximize network lifetime as a stochastic shortest path Markov decision process. We consider three types of channel information structure: global channel state information (CSI), channel statistics, and local CSI. For optimal scheduling using global CSI (i.e., the scheduler has the information of all sensors ’ instantaneous channel realizations), we propose an algorithm that obtains the optimal stationary scheduling policy with computational complexity reduced from exponential to polynomial in network size
Joint Optimization of Transmit Power-Time and Bit Energy Efficiency in CDMA Wireless Sensor Networks 1
, 2005
"... industrial partners. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. In this paper, we address the problem of minimizing energy consumption in a CDMA wireless ..."
Abstract
-
Cited by 9 (2 self)
- Add to MetaCart
(Show Context)
industrial partners. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. In this paper, we address the problem of minimizing energy consumption in a CDMA wireless sensor network (WSN), where multiple sensor nodes transmit data simultaneously to a common remote sink. A comprehensive energy consumption model is proposed, which accounts for both the transmit and circuit energy. Energy consumption is minimized by jointly optimizing the transmit power and transmission time for each active node in the network. The optimization problem is formulated as a non-convex optimization. Numerical as well as closed-form approximate analytical solutions are provided. For the numerical solution, we show that the formulation can be transformed into a convex geometric programming (GP), for which fast algorithms, such as Interior Point Method, can be applied. For the closed-form solution, we prove that the joint power/time optimization can be decoupled into two sequential sub-problems: optimization of transmit power with transmission time serving as a parameter, and then optimization of the transmission time. We show that the first sub-problem is a linear programming while the second one can be well approximated as a convex programming problem. Accordingly, closed-form solutions are found for both sub-problems, and hence for the original formulation. Taking advantage of these analytical results, we further derive the bit energy efficiency (BEE) performance for CDMA WSNs. Our results are verified through numerical examples and simulations.
Energy Efficient Clustering in Sensor Networks with Mobile Agents
, 2005
"... Wireless sensor networks with mobile access points are effective tools to collect data in a variety of environments. Low-cost and low-power sensors in the reachback operation contend for the channel to transmit their own data packets to the mobile agent. This data communication should be designed to ..."
Abstract
-
Cited by 8 (0 self)
- Add to MetaCart
Wireless sensor networks with mobile access points are effective tools to collect data in a variety of environments. Low-cost and low-power sensors in the reachback operation contend for the channel to transmit their own data packets to the mobile agent. This data communication should be designed to ensure energy efficiency and low latency. In this paper, we propose a clustering scheme for wireless sensor networks with reachback mobile agents (C-SENMA) toward that goal. C-SENMA groups sensors into clusters such that nodes communicate only with the nearest clusterhead (CH) and the CH takes the task of data aggregation and communication with the mobile agent. In our scheme, CHs use a low-overhead medium access control (MAC) mechanism very similar to the conventional ALOHA to contend for the channel. Using results from random geometry theory, we analyze the clustering performance under the realistic MAC algorithm. Our analysis enables us to obtain the optimal average cluster size which minimizes energy consumption. We justify our analysis results by extensive simulations according to various clustering parameters. Furthermore, we study the effect of underlying physical layer characteristics on the amount of energy reduction achievable by the proposed clustering architecture.
Critical issues in energy-constrained sensor networks: synchronization, scheduling, and acquisition
- Proc. 2005 Intl. Conf. on Acoustics, Speech, and Sig. Proc., (ICASSP’05
, 2005
"... Energy-constrained wireless sensor networks have conflicting requirements between the need to communicate, and the desire to avoid idle listening and thus save energy. Beneath this simple observation lies a complex design space that encompasses all layers of the radio through application. Broad desi ..."
Abstract
-
Cited by 5 (3 self)
- Add to MetaCart
(Show Context)
Energy-constrained wireless sensor networks have conflicting requirements between the need to communicate, and the desire to avoid idle listening and thus save energy. Beneath this simple observation lies a complex design space that encompasses all layers of the radio through application. Broad design principles include the desire to exploit resources external to the network, such as beacons and (perhaps mobile) access points that do not have strong energy constraints. We consider synchronization, scheduled communications rendezvous, and packet acquisition. Synchronization accuracy worsens with prediction interval, saves energy by enabling scheduling, but costs energy to maintain. Acquisition is probabilistic due to noise, fading, and synchronization error, with operating points defining energy-performance tradeoffs. 1.
Spatial Diversity Benefits by Means of Induced Fading
"... Multipath fading heavily contributes to the unreliability of wireless links and is normally seen as a negative phenomenon hindering proper radio communication. However, fading can also improve the chances of reliable communication over channels that would otherwise be unusable, as our experimental e ..."
Abstract
-
Cited by 4 (4 self)
- Add to MetaCart
(Show Context)
Multipath fading heavily contributes to the unreliability of wireless links and is normally seen as a negative phenomenon hindering proper radio communication. However, fading can also improve the chances of reliable communication over channels that would otherwise be unusable, as our experimental evidence shows. In the context of wireless sensor networks, we show that limited motion of the base station may be used to obtain a considerable spatial diversity benefit through the exploitation of induced fading. We compare our limited mobility approach to multi-antenna systems, which are commonly used to achieve spatial diversity, and we illustrate these concepts with the help of experimental results. Moreover, we analyze how spatial diversity relates to network lifetime. I.
1 Cooperative Diversity in Interference Limited Wireless Networks
"... Abstract — Using relays in wireless networks can potentially lead to significant capacity increases. However, within an asynchronous multi-user communication setting, relaying might cause more interference in the network, and significant sum-rate deterioration may be observed. In this work the effec ..."
Abstract
-
Cited by 4 (0 self)
- Add to MetaCart
(Show Context)
Abstract — Using relays in wireless networks can potentially lead to significant capacity increases. However, within an asynchronous multi-user communication setting, relaying might cause more interference in the network, and significant sum-rate deterioration may be observed. In this work the effect of cooperation in an interference limited, narrow-band wireless network is investigated. It is crucial to determine the optimal trade-off between the amount of throughput gain obtained via cooperation and the amount of interference introduced to the network. We quantify the amount of cooperation using the notion of a cooperative region for each active node. The nodes which lie in such a region are allowed to cooperate with the source. We adopt the decode-and-forward scheme at the relays and use the physical interference model to determine the probability that a relay node correctly decodes its corresponding source. Through numerical analysis and simulation, we study the optimal cooperative region size to maximize the network sum-rate and energy efficiency, based on network size, relay availability, node decoding threshold, and destination reception capability. It is shown that optimized system performance in terms of the network sum-rate and the power efficiency is significantly improved compared with cases where relay nodes are not exploited or where the cooperative region size is suboptimal. Index Terms — Cooperative diversity, sum-rate, interference, cooperation gain, cooperative region.
Scaling Properties of Routing Protocols in Sensor Networks With Mobile Access
, 2007
"... The task of routing streaming data in a sensor network is made arduous by the resource constraints imposed on each node. The control overhead of a routing protocol has to be minimized in order to preserve limited resources at the node. Furthermore, it is widely expected that the gateway of the senso ..."
Abstract
-
Cited by 3 (0 self)
- Add to MetaCart
The task of routing streaming data in a sensor network is made arduous by the resource constraints imposed on each node. The control overhead of a routing protocol has to be minimized in order to preserve limited resources at the node. Furthermore, it is widely expected that the gateway of the sensor network will not be static in many application scenarios, but will be moving around the network. The gateway could move to collect data, or because it is not associated with a specific location, but with a specific mobile user. We study
