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Topology Control in Wireless Ad Hoc and Sensor Networks
 ACM Computing Surveys
, 2005
"... Topology Control (TC) is one of the most important techniques used in wireless ad hoc and sensor networks to reduce energy consumption (which is essential to extend the network operational time) and radio interference (with a positive effect on the network traffic carrying capacity). The goal of thi ..."
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Cited by 304 (4 self)
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Topology Control (TC) is one of the most important techniques used in wireless ad hoc and sensor networks to reduce energy consumption (which is essential to extend the network operational time) and radio interference (with a positive effect on the network traffic carrying capacity). The goal of this technique is to control the topology of the graph representing the communication links between network nodes with the purpose of maintaining some global graph property (e.g., connectivity), while reducing energy consumption and/or interference that are strictly related to the nodes ’ transmitting range. In this article, we state several problems related to topology control in wireless ad hoc and sensor networks, and we survey stateoftheart solutions which have been proposed to tackle them. We also outline several directions for further research which we hope will motivate researchers to undertake additional studies in this field.
Topology control meets sinr: the scheduling complexity of arbitrary topologies
 in Proceedings of ACM MobiHoc
, 2006
"... To date, topology control in wireless ad hoc and sensor networks—the study of how to compute from the given communication network a subgraph with certain beneficial properties—has been considered as a static problem only; the time required to actually schedule the links of a computed topology with ..."
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Cited by 103 (9 self)
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To date, topology control in wireless ad hoc and sensor networks—the study of how to compute from the given communication network a subgraph with certain beneficial properties—has been considered as a static problem only; the time required to actually schedule the links of a computed topology without message collision was generally ignored. In this paper we analyze topology control in the context of the physical SignaltoInterferenceplusNoiseRatio (SINR) model, focusing on the question of how and how fast the links of a resulting topology can actually be realized over time. For this purpose, we define and study a generalized version of the SINR model and obtain theoretical upper bounds on the scheduling complexity of arbitrary topologies in wireless networks. Specifically, we prove that even in worstcase networks, if the signals are transmitted with correctly assigned transmission power levels, the number of time slots required to successfully schedule all links of an arbitrary topology is proportional to the squared logarithm of the number of network nodes times a previously defined static interference measure. Interestingly, although originally considered without explicit accounting for signal collision in the SINR model, this static interference measure plays an important role in the analysis of link scheduling with physical link interference. Our result thus bridges the gap between static graphbased interference models and the physical SINR model. Based on these results, we also show that when it comes to scheduling, requiring the communication links to be symmetric may imply significantly higher costs as opposed to topologies allowing unidirectional links.
Power Optimization in FaultTolerant Topology Control Algorithms for Wireless Multihop Networks
 in Proceedings of the 9th Annual International Conference on Mobile Computing and Networking. 2003
, 2003
"... In ad hoc wireless networks, it is crucial to minimize power consumption while maintaining key network properties. This work studies power assignments of wireless devices that minimize power while maintaining kfault tolerance. Specifically, we require all links established by this power setting be ..."
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Cited by 84 (6 self)
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In ad hoc wireless networks, it is crucial to minimize power consumption while maintaining key network properties. This work studies power assignments of wireless devices that minimize power while maintaining kfault tolerance. Specifically, we require all links established by this power setting be symmetric and form a kvertex connected subgraph of the network graph. This problem is known to be NPhard. We show current heuristic approaches can use arbitrarily more power than the optimal solution. Hence, we seek approximation algorithms for this problem. We present three approximation algorithms. The first algorithm gives an O(kα)approximation where α is the best approximation factor for the related problem in wired networks (the best α so far is O(log k).) With a more careful analysis, we show our second (slightly more complicated) algorithm is an O(k)approximation. Our third algorithm assumes that the edge lengths of the network graph form a metric. In this case, we present simple and practical distributed algorithms for the cases of 2 and 3connectivity with constant approximation factors. We generalize this algorithm to obtain an O(k 2c+2)approximation for general kconnectivity (2 ≤ c ≤ 4 is the power attenuation exponent). Finally, we show that these approximation algorithms compare favorably with existing heuristics. We note that all algorithms presented in this paper can be used to minimize power while maintaining kedge connectivity with guaranteed approximation factors.
Deploying Sensor Networks with Guaranteed Fault Tolerance
, 2005
"... We consider the problem of deploying or repairing a sensor network to guarantee a specified level of multipath connectivity (kconnectivity) between all nodes. Such a guarantee simultaneously provides fault tolerance against node failures and high overall network capacity (by the maxflow mincut t ..."
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Cited by 76 (4 self)
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We consider the problem of deploying or repairing a sensor network to guarantee a specified level of multipath connectivity (kconnectivity) between all nodes. Such a guarantee simultaneously provides fault tolerance against node failures and high overall network capacity (by the maxflow mincut theorem). We design and analyze the first algorithms that place an almostminimum number of additional sensors to augment an existing network into a kconnected network, for any desired parameter k. Our algorithms have provable guarantees on the quality of the solution. Specifically, we prove that the number of additional sensors is within a constant factor of the absolute minimum, for any fixed k. We have implemented greedy and distributed versions of this algorithm, and demonstrate in simulation that they produce highquality placements for the additional sensors.
Clustering Algorithms for Ad Hoc Wireless Networks
, 2004
"... An ad hoc network is a multihop wireless communication network supporting mobile users without any existing infrastructure. To become commercially successful, the technology must allow networks to support many users. A complication is that addressing and routing in ad hoc networks does not scale u ..."
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Cited by 51 (2 self)
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An ad hoc network is a multihop wireless communication network supporting mobile users without any existing infrastructure. To become commercially successful, the technology must allow networks to support many users. A complication is that addressing and routing in ad hoc networks does not scale up as easily as in the Internet. By introducing hierarchical addresses to ad hoc networks, we can effectively address this complication. Clustering provides a method to build and maintain hierarchical addresses in ad hoc networks. Here, we survey several clustering algorithms, concentrating on those that are based on graph domination. In addition, we describe results that show that building clustered hierarchies is affordable and that clustering algorithms can also be used to build virtual backbones to enhance network quality of service.
A Robust Interference Model for Wireless Ad Hoc Networks
 5th International Workshop on Algorithms for Wireless, Mobile, Ad Hoc and Sensor Networks (WMAN
, 2005
"... Among the foremost goals of topology control in wireless adhoc networks is interference reduction. This paper presents a receivercentric interference model featuring two main advantages over previous work. First, it reflects the fact that interference occurs at the intended receiver of a message. ..."
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Cited by 47 (5 self)
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Among the foremost goals of topology control in wireless adhoc networks is interference reduction. This paper presents a receivercentric interference model featuring two main advantages over previous work. First, it reflects the fact that interference occurs at the intended receiver of a message. Second, the presented interference measure is robust with respect to addition or removal of single network nodes. Regarding both of these aspects our model intuitively corresponds to the behavior of interference in reality. Based on this interference model, we show that currently known topology control algorithms poorly reduce interference. Motivated by the observation that already onedimensional network instances display the intricacy of the considered problem, we continue to focus on the socalled highway model. Setting out to analyze the special case of the exponential node chain, we eventually describe an algorithm guaranteeing to achieve a 4 √ ∆approximation of the optimal connectivitypreserving topology in the general highway model. 1.
Maximum Throughput and Fair Bandwidth Allocation in MultiChannel Wireless Mesh Networks
, 2006
"... Wireless mesh network is designed as an economical solution for lastmile broadband Internet access. In this paper, we study bandwidth allocation in multichannel multihop wireless mesh networks. Our optimization goals are to maximize the network throughput and, at the same time, to enhance fairnes ..."
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Cited by 35 (2 self)
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Wireless mesh network is designed as an economical solution for lastmile broadband Internet access. In this paper, we study bandwidth allocation in multichannel multihop wireless mesh networks. Our optimization goals are to maximize the network throughput and, at the same time, to enhance fairness. First, we formulate and present an Linear Programming (LP) formulation to solve the Maximum throughput Bandwidth Allocation (MBA) problem. However, simply maximizing the throughput may lead to a severe bias on bandwidth allocation among wireless mesh nodes. In order to achieve a good tradeoff between fairness and throughput, we consider a simple maxmin fairness model which leads to high throughput solutions with guaranteed maximum minimum bandwidth allocation values, and the wellknown Lexicographical MaxMin (LMM) model. Correspondingly, we formulate the Maxmin guaranteed Maximum throughput Bandwidth Allocation (MMBA) problem and the Lexicographical MaxMin Bandwidth Allocation (LMMBA) problem. For the former one, we present an LP formulation to provide optimal solutions and for the later one, we propose a polynomial time optimal algorithm.
Fair Sharing of Bandwidth in VANETs
 In Proc. of VANET 2005
, 2005
"... We address the challenge of how to share the limited wireless channel capacity for the exchange of safetyrelated information in a fully deployed vehicular ad hoc network (VANET). In particular, we study the situation that arises when the number of nodes sending periodic safety messages is too high ..."
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Cited by 29 (9 self)
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We address the challenge of how to share the limited wireless channel capacity for the exchange of safetyrelated information in a fully deployed vehicular ad hoc network (VANET). In particular, we study the situation that arises when the number of nodes sending periodic safety messages is too high in a specific area. In order to achieve a good performance of safetyrelated protocols, we propose to limit the load sent to the channel using a strict fairness criterion among the nodes. A formal definition of this problem is presented in terms of a maxmin optimization problem with an extra condition of pernode maximality. Furthermore, we propose FPAV, a power control algorithm which finds the optimum transmission range of every node, and formally prove its validity under idealistic conditions. Simulations are performed to visualize the result of FPAV in a couple of road situations. Finally, we discuss the issues that must be taken into account when implementing FPAV. 1
Topology Control in Ad hoc Wireless Networks with Hitchhiking
, 2004
"... In this paper, we address the Topology Control with Hitchhiking (TCH) problem. Hitchhiking [1] is a novel model introduced recently that allows combining partial messages to decode a complete message. By effective use of partial signals, a specific topology can be obtained with less transmission ..."
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Cited by 27 (1 self)
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In this paper, we address the Topology Control with Hitchhiking (TCH) problem. Hitchhiking [1] is a novel model introduced recently that allows combining partial messages to decode a complete message. By effective use of partial signals, a specific topology can be obtained with less transmission power. The objective of the TCH problem is to obtain a stronglyconnected topology with minimum total energy consumption. We prove the TCH problem to be NPcomplete and design a distributed and localized algorithm (DTCH) that can be applied on top of any symmetric, stronglyconnected topology to reduce total power consumption. We analyze the performance of our approach through simulation.
Analysis and Design of Effective and LowOverhead Transmission Power Control for VANETs
 in Proc. of the 5th ACM Int’l Workshop on Vehicular InterNetworking
, 2008
"... The control of vehicles ’ radio communication behavior to deal with the constrained available wireless bandwidth has been identified as a key challenge in VANETs. As an element of congestion control, this paper addresses distributed transmission power control as a means to control the impact of per ..."
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Cited by 23 (6 self)
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The control of vehicles ’ radio communication behavior to deal with the constrained available wireless bandwidth has been identified as a key challenge in VANETs. As an element of congestion control, this paper addresses distributed transmission power control as a means to control the impact of periodic transmissions (‘beacons’) on the overall channel load. By also considering recently discussed fairness issues, we first examine the tradeoff between the effectiveness of controlling the channel load on the one hand and the corresponding costs in terms of the required packet overhead on the other hand. We provide insights to the underlying estimation problems and present a sensitivity analysis with respect to nonhomogeneous vehicular traffic densities and nonperfect channel conditions. Second, based on the analysis, we propose a segmentbased power adjustment approach based on a distributed vehicle density estimation. The approach put forward in this paper reduces overhead by two orders of magnitude compared to previous approaches while still being effective in controlling the channel load.