LABS: Latency aware broadcast scheduling in uncoordinated Duty-Cycled Wireless Sensor Networks

doi:10.1016/j.jpdc.2014.07.011

Journal of Parallel and Distributed Computing

Volume 74, Issue 11, November 2014, Pages 3141-3152

https://doi.org/10.1016/j.jpdc.2014.07.011 Get rights and content

Highlights

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A novel broadcast scheduling algorithm for duty-cycled WSNs.
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Multiple transmissions capable of scheduling in one working period.
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Acceleration scheduling to reduce broadcast latency.
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Reducing the number of transmissions by exploring the properties of an independent set.

Abstract

Broadcast is a fundamental operation in Wireless Sensor Networks (WSNs) and plays an important role in a communication protocol design. In duty-cycled scenarios, a sensor node can receive a message only in its active time slot, which makes it more difficult to design collision-free scheduling for broadcast operations. Recent studies in this area have focused on minimizing broadcast latency and guaranteeing that all nodes receive a broadcast message. This paper investigates the problem of Minimum Latency Broadcast Scheduling in Duty-Cycled (MLBSDC) WSNs. By using special geometric properties of independent sets of a broadcast tree, we reduce the number of transmissions, consequently reducing the possibility of collision. Allowing multiple transmissions in one working period, our proposed Latency Aware Broadcast Scheduling (LABS) scheme provides a latency-efficient broadcast schedule. Theoretical analysis proves that the scheme has the same approximation ratio and complexity as the previous best algorithm for the MLBSDC problem. Moreover, simulation shows that the new scheme achieves up to 34%, 37%, and 21% performance improvement over previous schemes, in terms of latency, number of transmissions, and energy consumption, respectively.

Introduction

A wide range of services in Wireless Sensor Networks (WSNs) rely strongly on broadcasting, such as information dissemination, route discovery and code update [23]. Implementing effective network-wide broadcast scheduling is critical to improve the performance of WSNs. Like other communication operations in the wireless medium, broadcast scheduling suffers from collisions; when two or more nodes transmit messages to a common neighbor simultaneously, the common node will not able to receive any of the messages. Minimum Latency Broadcast Scheduling (MLBS) aims to find a collision-free schedule for broadcast with a minimum latency [3]. The problem is known to be NP-hard [8], and has been widely studied in conventional Wireless Ad hoc Networks (WANETs) where all nodes are assumed to be active all the time [8], [13], [7], [2], [20], [12], [26].

Sensor nodes, generally battery-powered, often operate in environments where power replenishment or replacement is not feasible. Meanwhile, many applications of WSNs need to last for a long time, for example for unattended habitat monitoring. A well-known approach to save energy is a duty-cycle method, in which a sensor node alternates its mode between sleeping and active to conserve energy [1]. However, the intermittent connections of a duty-cycled network make the MLBS problem different from conventional cases. In particular, a sensor node needs to transmit a message multiple times to its neighbor nodes at different active time slots. The multiple transmissions result in a longer broadcast latency and more energy consumption. The difference renders the Minimum Latency Broadcast Scheduling in Duty-Cycled (MLBSDC) WSNs problem complex, and existing algorithms for conventional WANETs cannot be directly applied to the new problem.

Hong et al. [10] claim the NP-hardness of MLBSDC in the Unit Disk Graphs (UDG) model, and proposed a duty-cycled-aware broadcast scheduling algorithm. The algorithm, called Enhanced LAyered Coloring (ELAC), achieves an approximation ratio of $24 T + 1$ , where $T$ denotes the number of time slots in a working period. Jiao et al. recently improved the ratio to $17 T$ with the One-To-All Broadcast (OTAB) algorithm in [15].

This paper presents a latency efficient scheduling scheme for the MLBSDC. The proposed scheme explores the fact that two transmissions at different time slots do not interfere with each other. It allows nodes to transmit at multiple time slots in a single working period to increase the coverage in each working period and to reduce broadcast latency. Our randomized simulation shows that the scheme improves more than 30% over existing schemes for both the latency and the number of transmissions. In the worst case, the scheme achieves the same time complexity, broadcast latency and number of transmissions as the OTAB.

The remainder of this paper is organized as follows. In Section 2, we discuss related work. Section 3 includes the network model, the problem formulation, and some related terminology. Section 4 presents the proposed algorithm, and then its performance is analyzed in Section 5. Section 6 shows performance evaluation results. Finally, we conclude the paper in Section 7, and discuss our future work.

Section snippets

Background and related work

The broadcast problem has been studied widely over the past few decades. In order to reduce the long latency due to collisions led by naive broadcast methods, such as blind flooding, several techniques have been proposed [22], [19], [24], [17], [16]. In these works, the authors use the nodes’ neighborhood information to determine whether a particular node needs to transmit a message. Many constraints of the broadcast problem have been considered, such as the number of collisions, number of

System model and assumptions

All sensor nodes are uniformly deployed in a square field with one randomized source node as in [10], [15], [29]. The network topology is modeled as a connected graph. Two sensor nodes form a bidirectional communication link and become a neighbor to each other whenever the Euclidean distance between them is within their transmission range. Each sensor node in the network is assigned a unique identifier.

In duty-cycled environments, time is divided into unit time slots. These discrete time slots

Motivation

So far, the layered approach has been utilized in many broadcast scheduling schemes, since it makes the broadcast operation controllable. Scheduling nodes individually for each layer, a layered scheme can easily obtain an upper bound of a broadcast schedule while ensuring that all nodes in the network receive a message. Fig. 3 compares a layered schedule to an optimal schedule. The example considers a duty-cycled network with $T = 4$ . We assume that all nodes in layer $k - 1$ or less have received a

Performance analysis

We establish the upper bound on the latency of a broadcast schedule produced by the LABS scheme first. For a duty-cycled WSN, we denote the broadcast latency of an optimal algorithm by $d_{opt}$ . In the worst case, there are $l_{\max} + 1$ non-empty layers in a broadcast tree $T_{B}$ of the network, since it requires at least $l_{\max} + 1$ time slots to accomplish all transmissions in the tree, $d_{opt} \geq l_{\max} + 1$ [10].

Theorem 1

The LABS scheme produces a $17 T$ -approximate solution for broadcast latency.

Proof

We denote the broadcast latency

Simulation environment

The proposed scheduling scheme is evaluated by the simulation configured similar to the one in [15]. All wireless sensor nodes are deployed in a square area of $200 m \times 200 m$ . Their locations are generated within the area according to a two-dimensional uniform random distribution. The interference range is the same as the transmission range. All nodes have the same duty-cycle, which equals $1 / T$ , and obtain their active time slots independently.

Moreover, the energy model of Mica2 platform [14] is

Conclusion

This paper presents a latency-efficient approximation scheme for the Minimum Latency Broadcast Scheduling in Duty-Cycled (MLBSDC) wireless sensor networks. We proved that our algorithm provides a collision-free broadcast schedule with the previous best approximation ratio and time complexity in the worst case. At the same time, the simulation results show that our proposed algorithm consistently outperforms existing schemes by 34%–44%, 37%–56%, and 21%–48% on broadcast latency, total

Acknowledgments

This research was supported in part by Korean government, under Brain Scouting Program (NIPA-HB603-12-1002), Basic Science Research Program (NRF-2013R1A1A2064302), PRCP (NRF-2010-0020210), and DCTANCM (IITP-14-911-05-006).

Duc Tai Le received the B.S. degree in Information Technology and M.S. degree in Computer Science from the University of Science, Ho Chi Minh City, Vietnam, in 2006 and 2010, respectively. From 2006 to 2010, he was a lecturer at the University of Science, Ho Chi Minh City, Vietnam. He is currently a Ph.D. candidate in the Department of Electrical and Computer Engineering, College of Information and Communication Engineering, Sungkyunkwan University, South Korea. His current research interests

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All transmissions of the two scheduling phases are involved in the performance evaluation of the proposed schemes. Their broadcast latency, total number of transmissions, and total energy consumption are compared with those of OTAB [34] and LABS [22]. We study the effect of different network parameters including number of nodes, transmission range and duty-cycle on the performance of these schemes.
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Thang Le Duc received the B.S. degree in Information Technology and M.S. degree in Computer Science from the University of Science, Ho Chi Minh City, Vietnam, in 2001 and 2006, respectively. From 2001 to 2006, he was a researcher at Center for Information Technology Development, Vietnam National University, Ho Chi Minh City. In 2006, he joined the University of Information Technology, Vietnam as a lecturer. He is currently a Ph.D. candidate in the Department of Electrical and Computer Engineering, College of Information and Communication Engineering, Sungkyunkwan University, South Korea. His current research interests include wireless ad hoc and sensor networks, pervasive computing, and distributed computing.

Vyacheslav V. Zalyubovskiy received the M.S. degree from Novosibirsk State University, Russia and the Ph.D. degree from the Sobolev Institute of Mathematics of the Siberian Branch of the Russian Academy of Sciences, both in Mathematics. Since 1984, he has been a scientific researcher at Sobolev Institute of Mathematics. In 2007, he has joined the College of Information and Communication Engineering, Sungkyunkwan University as research professor. His recent research focuses on the design and analysis of exact and approximation algorithms for combinatorial optimization problems and their applications, particularly in the areas of networking, planning and scheduling.

Dongsoo S. Kim received the M.S. degree in Computer Science from the University of Texas at Dallas, TX, USA, in 1994, and the Ph.D. degree in Computer Science and Engineering from the University of Minnesota, Minneapolis, MN, USA, in 1998. He worked as a research scientist for Electronics and Telecommunications Research Institute from 1986 to 1992, and as a project manager for Megaxess Inc. from 1998 to 2000. In 2000, he joined the Department of Electrical and Computer Engineering, Indiana Univ. Purdue Univ. Indianapolis, USA. He is currently an associate professor of the Department and a director of Center for Sensor and Ubiquitous Networking, IUPUI. He has joined the Department of Electrical and Computer Engineering of Sungkyunkwan University in 2012. His research includes switch networks, optical switches, network survivability, protection switching, network planning, QoS provisioning in the Internet, mobile ad hoc networks, mobility modeling, sensor networks, and power-aware routing.

Hyunseung Choo received the B.S. degree in mathematics from Sungkyunkwan University, Korea in 1988, the M.S. degree in computer science from the University of Texas at Dallas, USA in 1990, and the Ph.D. degree in computer science from the University of Texas at Arlington, USA in 1996. From 1997 to 1998, he was a patent examiner at Korean Industrial Property Office. Since 1998, he has joined the College of Information and Communication Engineering, Sungkyunkwan University, and is an associate professor and director of Convergence Research Institute. Since 2005, he is director of Intelligent HCI Convergence Research Center (eight-year research program) supported by the Ministry of Knowledge Economy (Korea) under the Information Technology Research Center support program supervised by the Institute of Information Technology Assessment. His research interests include wired/wireless/optical embedded networking, mobile computing, and grid computing. He is vice president of Korean Society for Internet Information (KSII). He has been editor-in-chief of the Journal of KSII for three years and journal editors of Journal of Communications and Networks, ACM Transactions on Internet Technology, International Journal of Mobile Communication, Springer-Verlag Transactions on Computational Science Journal, and editor of KSII Transactions on Internet and Information Systems since 2006. He has published over 200 papers in international journals and refereed conferences. He is a member of IEEE and ACM.

^☆: A preliminary version of this paper has appeared in the Proceeding of the International Conference on Information Networking (ICOIN), 2013.

¹: Dr. Kim is currently visiting Sungkyunkwan University under a project supported by National IT Industry Promotion Agency, Korea.

View full text

LABS: Latency aware broadcast scheduling in uncoordinated Duty-Cycled Wireless Sensor Networks☆

Highlights

Abstract

Introduction

Section snippets

Background and related work

System model and assumptions

Motivation

Performance analysis

Simulation environment

Conclusion

Acknowledgments

Energy conservation in wireless sensor networks: a survey

J. Ad Hoc Netw.

On broadcasting in radio networks—problem analysis and protocol design

IEEE Trans. Commun.

Unit disk graphs

Discrete Math.

A note on two problems in connexion with graphs

Numer. Math.

Approximation algorithms for data broadcast in wireless networks

IEEE Trans. Mob. Comput.

Minimizing broadcast latency and redundancy in ad hoc networks

IEEE/ACM Trans. Netw.

Minimum-transmission broadcast in uncoordinated duty-cycled wireless ad hoc networks

IEEE Trans. Veh. Technol.

Broadcast scheduling in interference environment

IEEE Trans. Mob. Comput.

Probability-based prediction and sleep scheduling for energy-efficient target tracking in sensor networks

IEEE Trans. Mob. Comput.

Minimum latency broadcast scheduling in duty-cycled multi-hop wireless networks

IEEE Trans. Parallel Distrib. Syst.