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Dwmac: a low latency, energy efficient demandwakeup mac protocol for wireless sensor networks
 Proceedings of the 9th ACM international
, 2008
"... Duty cycling is a widely used mechanism in wireless sensor networks (WSNs) to reduce energy consumption due to idle listening, but this mechanism also introduces additional latency in packet delivery. Several schemes have been proposed to mitigate this latency, but they are mainly optimized for ligh ..."
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Cited by 47 (4 self)
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Duty cycling is a widely used mechanism in wireless sensor networks (WSNs) to reduce energy consumption due to idle listening, but this mechanism also introduces additional latency in packet delivery. Several schemes have been proposed to mitigate this latency, but they are mainly optimized for light traffic loads. A WSN, however, could often experience bursty and high traffic loads, such as due to broadcast or convergecast traffic. In this paper, we present a new MAC protocol, called Demand Wakeup MAC (DWMAC), that introduces a new lowoverhead scheduling algorithm that allows nodes to wake up on demand during the Sleep period of an operational cycle and ensures that data transmissions do not collide at their intended receivers. This demand wakeup adaptively increases effective channel capacity during an operational cycle as traffic load increases, allowing DWMAC to achieve low delivery latency under a wide range of traffic loads including both unicast and broadcast traffic. We compare DWMAC with SMAC (with and without adaptive listening) and with RMAC using ns2 and show that DWMAC outperforms these protocols, with increasing benefits as traffic load increases. For example, under high unicast traffic load, DWMAC reduces delivery latency by 70 % compared to SMAC and RMAC, and uses only 50 % of the energy consumed with SMAC with adaptive listening. Under broadcast traffic, DWMAC reduces latency by more than 50 % on average while maintaining higher energy efficiency.
Nearly Constant Approximation for Data Aggregation Scheduling
 in Wireless Sensor Networks”, IEEE INFOCOM 2007
"... Abstract — Data aggregation is a fundamental yet timeconsuming task in wireless sensor networks. We focus on the latency part of data aggregation. Previously, the data aggregation algorithm of least latency [1] has a latency bound of ( ∆ − 1)R, where ∆ is the maximum degree and R is the network rad ..."
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Cited by 44 (14 self)
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Abstract — Data aggregation is a fundamental yet timeconsuming task in wireless sensor networks. We focus on the latency part of data aggregation. Previously, the data aggregation algorithm of least latency [1] has a latency bound of ( ∆ − 1)R, where ∆ is the maximum degree and R is the network radius. Since both ∆ and R could be of the same order of the network size, this algorithm can still have a rather high latency. In this paper, we designed an algorithm based on maximal independent sets which has an latency bound of 23R +∆ − 18. Here ∆ contributes to an additive factor instead of a multiplicative one; thus our algorithm is nearly constant approximation and it has a significantly less latency bound than earlier algorithms especially when ∆ is large. I.
MISTRAL: Efficient flooding in mobile adhoc networks
 In Proceedings of the 7th ACM Int’l Symp. on Mobile Ad Hoc Networking and Computing (MobiHoc
, 2006
"... Flooding is an important communication primitive in mobile adhoc networks and also serves as a building block for more complex protocols such as routing protocols. In this paper, we propose a novel approach to flooding, which relies on proactive compensation packets periodically broadcast by every ..."
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Cited by 33 (0 self)
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Flooding is an important communication primitive in mobile adhoc networks and also serves as a building block for more complex protocols such as routing protocols. In this paper, we propose a novel approach to flooding, which relies on proactive compensation packets periodically broadcast by every node. The compensation packets are constructed from dropped data packets, based on techniques borrowed from forward error correction. Since our approach does not rely on proactive neighbor discovery and network overlays it is resilient to mobility. We evaluate the implementation of Mistral through simulation and compare its performance and overhead to purely probabilistic flooding. Our results show that Mistral achieves a significantly higher node coverage with comparable overhead.
Minimumlatency broadcast scheduling in wireless ad hoc networks
 in Proceedings of INFOCOM, 2007
"... Abstract — A wide range of applications for wireless ad hoc networks are timecritical and impose stringent requirement on the communication latency. This paper studies the problem MinimumLatency Broadcast Scheduling (MLBS) in wireless ad hoc networks represented by unitdisk graphs. This problem i ..."
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Cited by 25 (4 self)
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Abstract — A wide range of applications for wireless ad hoc networks are timecritical and impose stringent requirement on the communication latency. This paper studies the problem MinimumLatency Broadcast Scheduling (MLBS) in wireless ad hoc networks represented by unitdisk graphs. This problem is NPhard. A trivial lower bound on the minimum broadcast latency is the radius R of the network with respect to the source of the broadcast, which is the maximum distance of all the nodes from the source of the broadcast. The previously bestknown approximation algorithm for MLBS produces a broadcast schedule with latency at most 648R. Inthispaper,we present three progressively improved approximation algorithms for MLBS. They produce broadcast schedules with latency at most 24R − 23, 16R − 15, andR + O (log R) respectively. I.
Low latency broadcast in multiradio multichannel multirate wireless mesh networks
 Third Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks SECON
, 2006
"... Abstract: We address the problem of minimizing the worstcase broadcast delay in multiradio multichannel multirate (MR 2MC) wireless mesh networks (WMN). The problem of ‘efficient ’ broadcast in such networks is especially challenging due to the numerous interrelated decisions that have to be ma ..."
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Cited by 20 (7 self)
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Abstract: We address the problem of minimizing the worstcase broadcast delay in multiradio multichannel multirate (MR 2MC) wireless mesh networks (WMN). The problem of ‘efficient ’ broadcast in such networks is especially challenging due to the numerous interrelated decisions that have to be made. The multirate transmission capability of WMN nodes, interference between wireless transmissions, and the hardness of optimal channel assignment adds complexity to our considered problem. We present four heuristic algorithms to solve the minimum latency broadcast problem for such settings and show that the ‘best ’ performing algorithms usually adapt themselves to the available radio interfaces and channels. We also study the effect of channel assignment on broadcast performance and show that channel assignment can affect the broadcast performance substantially. More importantly, we show that a channel assignment that performs well for unicast does not necessarily perform well for broadcast/multicast. To the best of our knowledge, this work constitutes the first contribution in the area of broadcast routing for MR 2MC WMN. I.
QueryBased Data Collection in Wireless Sensor Networks with Mobile Sinks
 In Proceedings of the 5th International Wireless Communications and Mobile Computing Conference (IWCMC 2009
, 2009
"... Abstract — Data collection is one of the most important functions provided by wireless sensor networks. In this paper, we study theoretical limitations of data collection and data aggregation in terms of delay and capacity for a wireless sensor network where n sensors are randomly deployed. We consi ..."
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Cited by 18 (3 self)
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Abstract — Data collection is one of the most important functions provided by wireless sensor networks. In this paper, we study theoretical limitations of data collection and data aggregation in terms of delay and capacity for a wireless sensor network where n sensors are randomly deployed. We consider different communication scenarios (single sink or multiple sinks, regularlydeployed or randomlydeployed sinks, with or without aggregation) under protocol interference model. For each scenario, we first propose a new collection/aggregation method and analyze its performance in terms of delay and capacity, then theoretically prove that our method can achieve the optimal order (i.e., its performance is within a constant factor of the optimal). Particularly, with a single sink, the capacity of data collection is in order of Θ(W) where W is the fixed datarate on individual links. With k sinks, the capacity of data collection is increased to Θ(kW) when k = O ( n n n) or Θ ( W) when k = Ω( log n log n log n). If each sensor can aggregate its receiving packets into a single packet to send, the capacity of data collection with a single sink W). is also increased to Θ ( n log n I.
Logarithmic inapproximability of the radio broadcast problem
 Journal of Algorithms
, 2004
"... We show that the radio broadcast problem is Ω(log n)inapproximable unless NP ⊆ BPTIME(n O(loglog n)). This is the first result on the hardness of approximation of this problem. Our reduction is based on the reduction from the LabelCover problem to the Set Cover problem due to Lund and Yannakakis [ ..."
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Cited by 18 (0 self)
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We show that the radio broadcast problem is Ω(log n)inapproximable unless NP ⊆ BPTIME(n O(loglog n)). This is the first result on the hardness of approximation of this problem. Our reduction is based on the reduction from the LabelCover problem to the Set Cover problem due to Lund and Yannakakis [LY94], and uses some new ideas.
Distributed algorithms for coloring and domination in wireless ad hoc networks
 In Proc. of FSTTCS
, 2004
"... Abstract. We present fast distributed algorithms for coloring and (connected) dominating set construction in wireless ad hoc networks. We present our algorithms in the context of Unit Disk Graphs which are known to realistically model wireless networks. Our distributed algorithms take into account t ..."
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Cited by 17 (0 self)
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Abstract. We present fast distributed algorithms for coloring and (connected) dominating set construction in wireless ad hoc networks. We present our algorithms in the context of Unit Disk Graphs which are known to realistically model wireless networks. Our distributed algorithms take into account the loss of messages due to contention from simultaneous interfering transmissions in the wireless medium. We present randomized distributed algorithms for (conflictfree) Distance2 coloring, dominating set construction, and connected dominating set construction in Unit Disk Graphs. The coloring algorithm has a time complexity of O( ∆ log 2 n) and is guaranteed to use at most O(1) times the number of colors required by the optimal algorithm. We present two distributed algorithms for constructing the (connected) dominating set; the former runs in time O( ∆ log 2 n) and the latter runs in time O(log 2 n). The two algorithms differ in the amount of local topology information available to the network nodes. Our algorithms are geared at constructing Well Connected Dominating Sets (WCDS) which have certain powerful and useful structural properties such as low size, low stretch and low degree. In this work, we also explore the rich connections between WCDS and routing in ad hoc networks. Specifically, we combine the properties of WCDS with other ideas to obtain the following interesting applications: – An online distributed algorithm for collisionfree, low latency, low redundancy and high throughput broadcasting. – Distributed capacity preserving backbones for unicast routing and scheduling. 1
Optimized stateless broadcasting in wireless multihop networks
 In INFOCOM
, 2006
"... Abstract — In this paper we present a simple and stateless ..."
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Cited by 17 (3 self)
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Abstract — In this paper we present a simple and stateless
An Approximation Algorithm for ConflictAware Broadcast Scheduling in Wireless Ad Hoc Networks
"... Broadcast scheduling is a fundamental problem in wireless ad hoc networks. The objective of a broadcast schedule is to deliver a message from a given source to all other nodes in a minimum amount of time. At the same time, in order for the broadcast to proceed as predicted in the schedule, it must n ..."
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Cited by 16 (0 self)
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Broadcast scheduling is a fundamental problem in wireless ad hoc networks. The objective of a broadcast schedule is to deliver a message from a given source to all other nodes in a minimum amount of time. At the same time, in order for the broadcast to proceed as predicted in the schedule, it must not contain parallel transmissions which can be conflicting based on the collision and interference parameters in the wireless network. Most existing work on this problem use a limited network model which accounts only for conflicts occurring inside the transmission ranges of the nodes. The broadcast schedules produced by these algorithms are likely to experience unpredictable delays when deployed in the network. This is because they do not take into consideration other important sources of conflict in parallel transmissions, namely the interference range and the carrier sensing range. In this paper we develop a conflictaware network model, which uses these parameters to increase the probability of scheduling conflictfree transmissions, and thereby improve the reliability of the broadcast schedule. We present and prove correctness of a constant approximation algorithm for minimumlatency broadcast scheduling under this network model. We also present a greedy heuristic algorithm for the same problem. Experimental results are provided to evaluate the performance of our algorithms. In addition, the algorithms are analyzed to justify their performance trends. Categories and Subject Descriptors: