Fundamentals of energy-constrained sensor network systems

Abstract

This article is an overview of energy-constrained sensor networks, focusing on energy-conserving communications and signal processing strategies. We assume battery-driven nodes, employing robust communications, with little or no fixed infrastructure. Our discussion includes architectures, communications connectivity, capacity and scalability, mobility, network localization and synchronization, distributed signal processing, and cross-layer issues. Because energy is a precious system resource, all aspects of the network must be designed with energy savings in mind. In particular, transmissions and idle listening must be minimized, which implies the use of duty cycling to the maximum extent possible. When external assets are available, for tasks such as network synchronization and node geolocation, these can greatly relieve the energy burden and significantly enhance network lifetime.

Elements of Sequential Detection with Applications to Sensor Networks

“…The associated stopped process can be defined as in (4), and we can invoke (under suitable regularity conditions, see above) the martingale optional stopping theorem, yielding (13) Neglecting the excess over the boundaries (this is also known as Wald's approximation), yields www.intechopen.com (15) that underly many of the approximate design formulas for sequential detectors. We therefore get (16) Reasoning in the same way under hypothesis 1 , but using as martingale the the inverse of the likelihood ratio 1/Λ n , we get (17) Putting together eqs. (16) and (17), immediately yields 1 (18) ( 19) We reiterate that the approximation involved follows from having neglected the excess over the boundaries 2 .…”

“…The remote units sense the environment and collect data relevant to the detection task, while the MA travels across the network domain and sequentially polls the sensors. Indeed, in the SENMA (SEnsor Network with Mobile Agents) architecture proposed in [16], see also [17][18][19], at each successive MA's snapshot the nodes falling within its field of view are queried for delivering their data. Oppositely to the intrinsic nature of the remote units, the MA can be a very reliable device with large power capabilities and adequate communication/computational properties.…”

Joint Adaptive Modulation and Adaptive MAC Protocols for Wireless Sensor Networks

“…The spectral efficiency is parameterized by the average transmit power and the BER, which lead to the expression for the constellation size as a function of the received SNR  [14]:…”

System co-optimization in wireless receiver design with TrACS

“…Energy in the sensor node is a limited resource [1][2][3]. The radio transceiver often strains this tenuous resource and therefore ultra low power transceiver designs are proposed to help the node conserve power [5,6,24].…”