An ad-hoc network of wireless static nodes is considered as it arises in a rapidly deployed, sensor based, monitoring system. Information is generated in certain nodes and needs to reach a set of designated gateway nodes. Each node may adjust its power within a certain range that determines the set of possible one hop away neighbors. Traffic forwarding through multiple hops is employed when the intended destination is not within immediate reach. The nodes have limited initial amounts of energy that is consumed in different rates depending on the power level and the intended receiver. We propose algorithms to select the routes and the corresponding power levels such that the time until the batteries of the nodes drain-out is maximized. The algorithms are local and amenable to distributed implementation. When there is a single power level, the problem is reduced to a maximum flow problem with node capacities and the algorithms converge to the optimal solution. When there are multiple power levels then the achievable lifetime is close to the optimal (that is computed by linear programming) most of the time. It turns out that in order to maximize the lifetime, the traffic should be routed such that the energy consumption is balanced among the nodes in proportion to their energy reserves, instead of routing to minimize the absolute consumed power.

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Routing in power-controlled wireless sensor networks is formulated as an optimization problem with the goal of maximizing the system lifetime. Considering that the information is delivered in the form of packets, we identified the problem as an integer programming problem. It is known that the system lifetime can be significantly extended by using a link metric that utilizes the information about the residual energy of the sensor nodes as well as the energy expenditure in transmission of a unit information over the wireless links. In this paper, some of the routing algorithms are proposed and examined in order to find the best link cost function and the method of shortest path calculation. The performance comparison is made through simulation in a typical battlefield scenario where sensors detecting a moving target vehicle periodically send a reporting packet to one of the gateway nodes. The results are also compared with the optimal solution obtained by the linear programming relaxation of the problem, which showed close-to-optimal performance.

We use concepts from communication theory to characterize information hiding schemes: the amount of information that can be hidden, its perceptibility, and its robustness to removal can be modeled using the quantities channel capacity, signal-to-noise ratio, and jamming margin. We then introduce new information hiding schemes whose parameters can easily be adjusted to trade off capacity, imperceptibility, and robustness as required in the application. The theory indicates the most aggressive feasible parameter settings. We also introduce a technique called predistortion for increasing resistance to JPEG compression. Analogous tactics are presumably possible whenever a model of anticipated distortion is available.

An ad-hoc network of wireless static nodes is considered as it arises in a rapidly deployed, sensor based, monitoring system. Information is generated in certain nodes and needs to reach some designated gateway node. Each node may adjust its power within a certain range that determines the set of possible one hop away neighbors. Traffic forwarding through multiple hops is employed when the intended destination is not within immediate reach. The nodes have limited initial amounts of energy that are consumed in different rates depending on the power level and the intended receiver. We propose algorithms to select the routes and the corresponding power levels such that the time until the batteries of the nodes drain-out is maximized. The algorithms are local and amenable to distributed implementation.

Abstract not found

In this paper, we address the problem of providing traffic quality of service and energy efficiency in ad hoc wireless networks. We consider a network that is shared by a set of sources, each one communicating with its corresponding destination using multiple routes. Each source is associated with a utility function which increases with the total traffic flowing over the available source-destination routes. The network lifetime is defined as the time until the first node in the network runs out of energy. We formulate the problem as one of maximizing the sum of the sources' utilities subject to the required constraint on network lifetime. We present a primal formulation of the problem, which uses penalty functions to take into account the system constraints, and we introduce a new methodology for solving the problem. The proposed approach leads to a flow control algorithm, which provides the optimal sources' rate and can be easily implemented in a distributed manner. When compared with the minimum transmission energy routing scheme, the proposed algorithm gives significantly higher sources' rates for same network lifetime guarantee.

The physical user interface is an increasingly significant factor limiting the effectiveness of our interactions with and through technology. This thesis introduces Electric Field Imaging, a new physical channel and inference framework for machine perception of human action. Though electric field sensing is an important sensory modality for several species of fish, it has not been seriously explored as a channel for machine perception. Technological applications of field sensing, from the Theremin to the capacitive elevator button, have been limited to simple proximity detection tasks. This thesis presents a solution to the inverse problem of inferring geometrical information about the configuration and motion of the human body from electric field measurements. It also presents simple, inexpensive hardware and signal processing techniques for making the field measurements, and several new applications of electric field sensing. The signal

In this paper we propose a routing protocol for wireless ad hoc networks whose nodes are largely battery powered. The battery capacity of the nodes is viewed as a common resource of the system and its use is to be optimized. Results from a previous study on battery management have shown that: (1) pulsed current discharge outperforms constant current discharge, (2) battery capacity can be improved by using a bursty discharge pattern due to charge recovery effects that take place during idle periods, (3) given a certain value of current drawn off the battery, higher current impulses degrade battery performance, even if the percentage of higher current impulses is relatively small. We develop a network protocol based on these findings. This protocol favors routes whose links have a low energy cost. We also distribute multihop traffic in a manner that allows all nodes a good chance to recover their battery energy reserve.

Wireless mobile ad hoc stations have limited battery capacity. Hence, ad hoc routing protocols ought to be energy conservative. However, The simulation studies carried out for table-driven and on-demand ad hoc routing protocols fall short of examining essential power-based performance metrics, such as average node and network lifetime, energy-based protocol fairness, average dissipated energy per protocol, and standard deviation of the energy dissipated by each individual node. In this paper, we present a thorough energy-based performance study of poweraware routing protocols for wireless mobile ad hoc networks. Our energy consumption model is based on a detailed implementation of the IEEE 802.11 physical layer convergence protocol (PLCP) and medium access control (MAC) sublayers. To our best knowledge, this is the first such detailed performance study. Moreover, we propose some novel enhancements to routing in wireless ad hoc networks that enables the admission of flows without jeopardizing the limited energy of the wireless stations.