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ABSTRACT: In this paper we study the asymptotic minimum energy (which is defined as the minimum transporting energy ) required to transport (via multiple hops) data packets from a source to a destination. Under the assumptions that nodes are distributed according to a Poisson point process with node density n in a unit-area square and the distance between a source and a destination is of constant order, we prove that the minimum transporting energy is Theta( n <sup>(1-alpha)/2</sup>) with probability approaching one as the node density goes to infinity, where alpha is the path loss exponent. We demonstrate use of the derived results to obtain the bounds of the capacity of wireless networks that operate in UWB. In particular, we prove the transport capacity of UWB-operated networks is Theta( n <sup>(alpha-1)/2</sup>) with high probability. We also carry out simulations to validate the derived results and to estimate the constant factor associated with the bounds on the minimum energy. The simulation results indicate that the constant associated with the minimum energy converges to the source-destination distance.
IEEE/ACM Transactions on Networking 11/2008; · 2.03 Impact Factor
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ABSTRACT: An important issue in wireless ad hoc networks is to reduce the transmission power subject to certain connectivity requirement. In this paper, we study the fundamental scaling law of the minimum total power (termed as critical total power) required to ensure k -connectivity in wireless networks. Contrary to several previous results that assume all nodes use a (minimum) common power, we allow nodes to choose different levels of transmission power. We show that under the assumption that wireless nodes form a homogeneous Poisson point process with density lambda in a unit square region [0, 1]<sup>2</sup>, the critical total power required to maintain k-connectivity is Theta((Gamma(c/2 + k)/(k - 1)!) lambda<sup>1-c/2</sup>) with probability approaching one as lambda goes to infinity, where c is the path loss exponent. If k also goes to infinity, the expected critical total power is of the order of k<sup>c/2</sup> lambda<sup>1-c/2</sup>. Compared with the results that all nodes use a common critical transmission power for maintaining k-connectivity, we show that the critical total power can be reduced by an order of (log lambda)<sup>c/2</sup> by allowing nodes to optimally choose different levels of transmission power. This result is not subject to any specific power/topology control algorithm, but rather a fundamental property of wireless networks.
IEEE/ACM Transactions on Networking 05/2008; · 2.03 Impact Factor
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ABSTRACT: Wireless sensor networks have gained considerable attention in the past few years. They have found application domains in battlefield communication, homeland security, pollution sensing, and traffic monitoring. As such, there has been an increasing need to define and develop simulation frameworks for carrying out high-fidelity WSN simulation. In this article we present a modeling, simulation, and emulation framework for WSNs in J-Sim - an open source, component-based compositional network simulation environment developed entirely in Java. This framework is built on the autonomous component architecture and extensible internetworking framework of J-Sim, and provides an object-oriented definition of target, sensor, and sink nodes, sensor and wireless communication channels, and physical media such as seismic channels, mobility models, and power models (both energy-producing and energy-consuming components). Application-specific models can be defined by subclassing classes in the simulation framework and customizing their behaviors. We also include in J-Sim a set of classes and mechanisms to realize network emulation. We demonstrate the use of the proposed WSN simulation framework by implementing several well-known localization, geographic routing, and directed diffusion protocols, and perform performance comparisons (in terms of the execution time incurred and memory used) in simulating WSN scenarios in J-Sim and ns-2. The simulation study indicates the WSN framework in J-Sim is much more scalable than ns-2 (especially in memory usage). We also demonstrate the use of the WSN framework in carrying out real-life full-fledged Future Combat System (FCS) simulation and emulation
IEEE Wireless Communications 09/2006; · 2.58 Impact Factor
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ABSTRACT: Wireless sensor networks (WSNs) have gained considerable attention in the past few years. As such, there has been an increasing need for defining and developing simulation frameworks for carrying out high-fidelity WSN simulation. In this paper, the authors presented a modeling and simulation framework for WSNs in J-Sim - an open-source, component-based compositional network simulation environment that is developed entirely in Java. This framework is built upon the autonomous component architecture (ACA) and the extensible internetworking framework (INET) of J-Sim, and provides an object-oriented definition of (i) target, sensor and sink nodes, (ii) sensor and wireless communication channels, and (iii) physical media such as seismic channels, mobility model and power model (both energy-producing and energy-consuming components). Application-specific models can be defined by sub-classing classes in the simulation framework and customizing their behaviors. The use of the proposed WSN simulation framework was demonstrated by implementing several well-known localization, geographic routing, and directed diffusion protocols. In addition, performance comparisons were performed (in terms of execution time incurred, and the memory used) in simulating several typical WSN scenarios in J-Sim and ns-2. The simulation study indicates that the proposed WSN simulation framework in J-Sim is much more scalable than ns-2 (especially in memory usage).
Simulation Symposium, 2005. Proceedings. 38th Annual; 05/2005
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ABSTRACT: In this paper, we investigate the minimum total power (termed as critical total power) required to ensure asymptotic k-connectivity in heterogeneous wireless networks where nodes may transmit using different levels of power. We show that under the assumption that wireless nodes form a homogeneous Poisson point process with density λ on a unit square region [0, 1]<sup>2</sup> and the Toroidal model [M.D. Penrose, 1997], the critical total power required for maintaining k-connectivity is θ((Γ(e/2+k))/((k-1)l)λ<sup>1-e</sup>2/) with probability approaching one as λ goes to infinity, where e is the path loss exponent. Compared with the results that all nodes use a common critical transmission power for maintaining k-connectivity [M.D. Penrose, 1999], [P.-J. Wan and C. Yi, 2004], we show that the critical total power can be reduced by an order of (log λ)e/2 by allowing nodes to optimally choose different levels of transmission power. This result is not subject to any specific power/topology control algorithm, but rather a fundamental property in wireless networks.
INFOCOM 2005. 24th Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings IEEE; 04/2005
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ABSTRACT: In this paper, we study how the achievable throughput scales in a wireless network with randomly located nodes as the number of nodes increases, under a communication model where (i) each node has a maximum transmission power W<sub>O</sub> and is capable of utilizing B Hz of bandwidth and (ii) each link can obtain a channel throughput according to the Shannon capacity. Under the limit case that B tends to infinity, we show that each node can obtain a throughput of θ(n<sup>(α-1)</sup>2/) where n is the density of the nodes and α > 1 is the path loss exponent. Both the upper bound and lower bound are derived through percolation theory. In order to derive the capacity bounds, we have also derived an important result on random geometric graphs: if the distance between two points in a Poisson point process with density n is non-diminishing, the minimum power route requires a power rate at least Ω(n<sup>(1-α)</sup>2/). Our results show that the most promising approach to improving the capacity bounds in wireless ad hoc networks is to employ unlimited bandwidth resources, such as the ultra wide band (UWB).
INFOCOM 2005. 24th Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings IEEE; 04/2005
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ABSTRACT: Bluetooth is a promising new wireless technology that enables portable devices to form short-range wireless ad hoc networks. In this paper, we present a new, distributed Bluetooth scatternet formation algorithm, called loop scatternet formation, which forms scatternets with slave/slave bridges only. In addition to meeting the criteria of maintaining connectivity, minimizing the number of piconets and the maximum degree of devices, the proposed algorithm formalizes the notion of network diameter and node contention. The loop scatternet thus formed incurs a much smaller network diameter and the number of node pairs for which a device has to serve, as a relay node is significantly smaller than that in the other types of scatternets. To validate the design, we derive the bounds of the number of piconets, the network diameter, and the maximum node contention. We also conduct ns-2 simulation to evaluate the performance of loop scatternets. Both analytical and simulation results validate the desirable features of loop scatternets.
Communications, 2003. ICC '03. IEEE International Conference on; 06/2003
