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25
Geometric Spanners for Wireless Ad Hoc Networks
 IEEE Transactions on Parallel and Distributed Systems
, 2003
"... We propose a new geometric spanner for static wireless ad hoc networks, which can be constructed efficiently in a localized manner. It integrates the connected dominating set and the local Delaunay graph to form a backbone of the wireless network. ..."
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Cited by 95 (27 self)
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We propose a new geometric spanner for static wireless ad hoc networks, which can be constructed efficiently in a localized manner. It integrates the connected dominating set and the local Delaunay graph to form a backbone of the wireless network.
Efficient distributed lowcost backbone formation for wireless networks
 IEEE Transactions on Parallel and Distributed Systems
, 2006
"... Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless networks. Previous methods are mostly designed to minimize the backbone size. However, in many applications, it is desirable to construct a backbone with small cost when eac ..."
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Cited by 54 (8 self)
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Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless networks. Previous methods are mostly designed to minimize the backbone size. However, in many applications, it is desirable to construct a backbone with small cost when each wireless node has a cost of being in the backbone. In this paper, we first show that previous methods specifically designed to minimize the backbone size may produce a backbone with a large cost. We then propose an efficient distributed method to construct a weighted sparse backbone with low cost. We prove that the total cost of the constructed backbone is within a small constant factor of the optimum for homogeneous networks when either the nodes ’ costs are smooth or the network maximum node degree is bounded. We also show that with a small modification the constructed backbone is efficient for unicast: the total cost (or hop) of the least cost (or hop) path connecting any two nodes using backbone is no more than 3 (or 4) times of the least cost (or hop) path in the original communication graph. As a side product, we give an efficient overlay based multicast structure whose total cost is no more than 10 times of the minimum when the network is modeled by UDG. Our theoretical results are corroborated by our simulation studies.
Expected Data Rate: An Accurate HighThroughput Path Metric For MultiHop Wireless Routing
, 2005
"... We present a new metric, Expected Data Rate (EDR), for accurately finding highthroughput paths in multihop ad hoc wireless networks. Our metric is based upon a new model for transmission interference which is a critical factor in determining path throughput. We construct a realistic and practical ..."
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Cited by 22 (2 self)
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We present a new metric, Expected Data Rate (EDR), for accurately finding highthroughput paths in multihop ad hoc wireless networks. Our metric is based upon a new model for transmission interference which is a critical factor in determining path throughput. We construct a realistic and practical transmission interference model by (1) determining transmission contention degree of each link as a function of the wireless link loss, (2) quantifying the impact of the wireless link loss on medium access backoff, and (3) considering possible concurrent transmissions when two links do not interfere with each other. Our transmission interference model also takes the nonoptimality of IEEE 802.11 medium access scheduling into account. Using extensive ns2 simulations of IEEE 802.11 ad hoc networks, we find that EDR can accurately determine the achievable data rates of ad hoc paths, thereby significantly outperforming the other existing metrics.
Enhancing Cellular Multicast Performance Using Ad Hoc Networks
, 2005
"... Although multicast communication is wellsuited to shared wireless links, receiver heterogeneity impedes the use of multicast in wireless networks. In this paper, we examine an approach that addresses the receiver heterogeneity problem in cellular multicast with the help of an additional IEEE 802.1 ..."
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Cited by 17 (2 self)
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Although multicast communication is wellsuited to shared wireless links, receiver heterogeneity impedes the use of multicast in wireless networks. In this paper, we examine an approach that addresses the receiver heterogeneity problem in cellular multicast with the help of an additional IEEE 802.11 ad hoc network. The basic idea is to allow the cellular receivers experiencing poor channel conditions to use the ad hoc network to connect to those cellular receivers that are experiencing good cellular channel conditions. The good receivers (called proxies) relay multicast data to the poor receivers through the ad hoc network. We specifically consider the third generation cellular high data rate (HDR) Broadcast/Multicast Services (BCMCS). We develop a new routing algorithm to find efficient ad hoc paths from the proxies to the cellular multicast receivers. Unlike existing algorithms [1], our routing algorithm considers the effect of ad hoc path interference. Using simulations of an HDR BCMCS network in conjunction with an IEEE ad hoc network, we show that our algorithm improves the receiver goodput by up to 280% compared to that obtained without using ad hoc paths. We also show that our algorithm achieves up to 98 % higher receiver goodput in comparison to the greedy algorithm proposed in [1].
Simple Approximation Algorithms and PTASs for Various Problems in Wireless Ad Hoc Networks
, 2005
"... A wireless ad hoc network is often composed of a set V of n wireless devices distributed in a twodimensional domain. For each wireless device (also called node) u ∈ V, there is a transmission region within which signaltonoiseratio (SNR) is at least a threshold γ so that the signal transmitted by ..."
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Cited by 9 (6 self)
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A wireless ad hoc network is often composed of a set V of n wireless devices distributed in a twodimensional domain. For each wireless device (also called node) u ∈ V, there is a transmission region within which signaltonoiseratio (SNR) is at least a threshold γ so that the signal transmitted by u can be correctly received by other nodes with high probability. The transmission region is often modeled as a disk centered at the node u. In addition, for each node u, there is an interference region within which the transmission from u makes the signaltointerferenceandnoiseratio (SINR) of the legitimate receiver smaller than the threshold γ so that the legitimate receiver cannot correctly receive the message from the legitimate transmitter. In this paper, we first present new graph models to model the communication graphs and the interference graphs defined by wireless ad hoc networks with attention to interferencefree channel assignment or scheduling. Then we propose some simple approximation algorithms and/or PTASs (polynomial time approximation scheme) to approximate several classical graph problems such as maximum independent set, minimum vertex cover and minimum vertex coloring in these graph models. In addition, we also discuss various possible applications for these simple approximation algorithms and/or PTASs in wireless ad hoc networks.
Maximum traffic scheduling and capacity analysis for ieee 802.15.3 high data rate MAC protocol
 Vehicular Technology Conference, 2003. VTC 2003Fall. 2003 IEEE 58th, 3:1678–1682 Vol.3
, 2003
"... Abstract — IEEE 802.15.3 is designed to provide low complexity, low cost, low power consumption and high data rate wireless connectivity among devices within wireless personal area networks (WPAN). A piconet is a basic topology of WPAN and is defined as a collection of one or more associated device ..."
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Cited by 8 (0 self)
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Abstract — IEEE 802.15.3 is designed to provide low complexity, low cost, low power consumption and high data rate wireless connectivity among devices within wireless personal area networks (WPAN). A piconet is a basic topology of WPAN and is defined as a collection of one or more associated devices that share a single piconet coordinator (PNC). One functionality of a PNC is to schedule traffic of a piconet. But the scheduling method of a PNC is out of the scope of IEEE 802.15.3 draft standard. This paper proposes a scheduling method which is called Maximum Traffic (MT) scheduling for IEEE 802.15.3. MT scheduling guarantees that total transmission data is maximum at any point of time and the needed time slots for transmission is minimum. MT scheduling is designed and analyzed by the properties of a graph coloring problem. Furthermore, the reasonable number of devices for a piconet and the durations of Contention Access Period (CAP) and Contention Free Period (CFP) are also investigated by this paper. I.
OVSFCDMA code assignment for wireless ad hoc networks
 ACM DialM
, 2004
"... Orthogonal Variable Spreading Factor (OVSF) CDMA code consists of an infinite number of codewords with variable rates, in contrast to the conventional orthogonal fixedspreadingfactor CDMA code. Thus, it provides a means of supporting of variable rate data service at low hardware cost. However, assi ..."
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Cited by 7 (3 self)
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Orthogonal Variable Spreading Factor (OVSF) CDMA code consists of an infinite number of codewords with variable rates, in contrast to the conventional orthogonal fixedspreadingfactor CDMA code. Thus, it provides a means of supporting of variable rate data service at low hardware cost. However, assigning OVSFCDMA codes to wireless ad hoc nodes posts a new challenge since not every pair of OVSFCDMA codewords are orthogonal to each other. In an OVSFCDMA wireless ad hoc network, a code assignment has to be conflictfree, i.e., two nodes can be assigned the same codeword or two nonorthogonal codewords if and only if their transmission will not interfere with each other. The throughput (resp., bottleneck) of a code assignment is the sum (resp., minimum) of the rates of the assigned codewords. The maxthroughput (resp., maxbottleneck) conflictfree code assignment problem seeks a conflictfree code assignment which achieves the maximum throughput (resp., bottleneck). In this paper, we present several efficient methods for conflictfree code assignment in OVSFCDMA wireless ad hoc networks. Each method is proved to be either a constantapproximation for maxthroughput conflictfree code assignment problem, or a constantapproximation for maxbottleneck conflictfree code assignment problem, or constantapproximations for both problems simultaneously.
Theoretically Good Distributed CDMA/OVSF Code Assignment for Wireless Ad Hoc Networks
 Tech Report, IIT, 2004, http://www.cs.iit.edu/∼xli/publicationsselect.htm XiangYang Li and PengJun Wan
"... Abstract. We present several distributed CDMA/OVSF code assignment algorithms for wireless ad hoc networks modelled by unit disk graph (UDG). We first give a distributed code assignment whose total throughput is within a constant factor of the optimum. Then we give a distributed method such that the ..."
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Cited by 6 (1 self)
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Abstract. We present several distributed CDMA/OVSF code assignment algorithms for wireless ad hoc networks modelled by unit disk graph (UDG). We first give a distributed code assignment whose total throughput is within a constant factor of the optimum. Then we give a distributed method such that the minimum rate achieved is within a constant factor of the optimum. A distributed method that can approximate both the minimum rate and total throughput is also presented. All our methods use only O(n) total messages (each with O(log n) bits)for an ad hoc wireless network of n nodes modelled by UDG.
Scheduling algorithms for treebased data collection in wireless sensor networks
 In Theoretical Aspects of Distributed Computing in Sensor Networks, Nicoletseas S, Rolim J (eds). Springer Verlag, 2010; 439–477, DOI: 10.1007/9783642148491_14. [Accessed on 06
, 2012
"... Abstract Data collection is a fundamental operation in wireless sensor networks (WSN) where sensor nodes measure attributes about a phenomenon of interest and transmit their readings to a common base station. In this chapter, we survey contentionfree Time Division Multiple Access (TDMA) based sched ..."
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Cited by 6 (0 self)
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Abstract Data collection is a fundamental operation in wireless sensor networks (WSN) where sensor nodes measure attributes about a phenomenon of interest and transmit their readings to a common base station. In this chapter, we survey contentionfree Time Division Multiple Access (TDMA) based scheduling protocols for such data collection applications over treebased routing topologies. We classify the algorithms according to their common design objectives, identifying the following four as the most fundamental and most studied with respect to data collection in WSNs: (i) minimizing schedule length, (ii) minimizing latency, (iii) minimizing energy consumption, and (iv) maximizing fairness. We also describe the pros and cons of the underlying design constraints and assumptions, and provide a taxonomy according to these metrics. Finally, we discuss some open problems together with future research directions. Data collection from a set of sensors to a common sink over a treebased routing topology is a fundamental traffic pattern in wireless sensor networks (WSNs). This
Efficient Distributed LowCost Backbone Formation for Wireless Networks
"... Abstract—Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless ad hoc or sensor networks recently. Previous methods are mostly designed to minimize the size of the backbone. However, in many applications, it is desirable to const ..."
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Cited by 4 (1 self)
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Abstract—Backbone has been used extensively in various aspects (e.g., routing, route maintenance, broadcast, scheduling) for wireless ad hoc or sensor networks recently. Previous methods are mostly designed to minimize the size of the backbone. However, in many applications, it is desirable to construct a backbone with small cost when each wireless node has a cost of being in the backbone. In this paper, we first show that previous methods specifically designed to minimize the backbone size may produce a backbone with large cost. Then, an efficient distributed method to construct a weighted backbone with low cost is proposed. We prove that the total cost of the constructed backbone is within a small constant factor of the optimum for homogeneous networks when either the nodes’ costs are smooth (i.e., the maximum ratio of costs of adjacent nodes is bounded) or the network maximum node degree is bounded. We also show that, with a small modification, the backbone is efficient for unicast: The total cost (or hop) of the least cost (or hop) path connecting any two nodes using backbone is no more than three (or four) times the least cost (or hop) path in the original communication graph. Our theoretical results are corroborated by our simulation studies. Finally, we discuss several possible ad hoc network applications of our proposed backbone formation algorithms. Index Terms—Connected dominating set, clustering, distributed algorithm, wireless ad hoc networks. 1