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Showing papers in "Wireless Communications and Mobile Computing in 2012"


Journal ArticleDOI
TL;DR: This paper discusses mobility management of mobile sensors for the purposes of forming a better WSN, enhancing network coverage and connectivity, and relocating some sensors and introduces path-planning methods for data ferries to relay data between isolated sensors and to extend a WSN's lifetime.
Abstract: Wireless sensor networks (WSNs) offer a convenient way to monitor physical environments. In the past, WSNs are all considered static to continuously collect information from the environment. Today, by introducing intentional mobility to WSNs, we can further improve the network capability on many aspects, such as automatic node deployment, flexible topology adjustment, and rapid event reaction. In this paper, we survey recent progress in mobile WSNs and compare works in this field in terms of their models and mobility management methodologies. The discussion includes three aspects. Firstly, we discuss mobility management of mobile sensors for the purposes of forming a better WSN, enhancing network coverage and connectivity, and relocating some sensors. Secondly, we introduce path-planning methods for data ferries to relay data between isolated sensors and to extend a WSN's lifetime. Finally, we review some existing platforms and discuss several interesting applications of mobile WSNs. Copyright © 2010 John Wiley & Sons, Ltd.

97 citations


Journal ArticleDOI
TL;DR: A novel topology control algorithm called Adaptive Random Clustering (ARC) is proposed to form a cluster network with required coverage and connectivity without location information and results demonstrate that required Coverage and connectivity can be satisfied and network lifetime is prolonged significantly.
Abstract: One of the most challenging issues in wireless sensor networks is to meet the requirements of coverage and connectivity under given energy constraints. Most existing coverage and connectivity algorithms work to form tree networks when sensor nodes do not have location information of themselves. However, a tree topology network does not perform well in terms of energy efficiency and scalability if compared with a cluster network. In this paper, a novel topology control algorithm called Adaptive Random Clustering (ARC) is proposed to form a cluster network with required coverage and connectivity without location information. The performance of its coverage intensity and connectivity is analyzed based on the characteristics of cluster topology, and their proper parameters are determined. ARC inherits an excellent energy efficiency from cluster topology and avoids the collisions and overhearing of data packets. A good scalability can be achieved as only a limited number of channels are needed in ARC for a large-scale network. Furthermore, ARC can adjust the number of active nodes adaptively according to the required coverage to balance the energy consumption. Simulation results demonstrate that required coverage and connectivity can be satisfied and network lifetime is prolonged significantly. Copyright © 2010 John Wiley & Sons, Ltd.

54 citations


Journal ArticleDOI
TL;DR: The results show that positioning systems with adequate accuracy can be built with the proposed schemes, and it is expected that these proposed schemes to be integrated in multitude of systems with context-aware applications, which use location information.
Abstract: The newer context-aware applications require many inputs and amongst them the location information is one of the most important. In the near future, we see the potential in using wireless sensors deployed inside buildings to support in generating the location information besides their other routine tasks. This paper records the efforts involved in designing and prototyping a centralized indoor positioning system for tracking a target's position. We present an in-depth discussion on the RSSI based positioning algorithms both, range-based and range-free. Considering that the signal strength can be distorted heavily due to multi-path and shadowing, we have proposed the weighing schemes to leverage the credibility of the measured RSSI values. For online tracking, we have also proposed boundary selection and local grid scanning to lower the searching time, and the RSSI data dissemination and collection schemes to reduce traffic overhead. Evaluations have been done in both the field measurements and with an RSSI generator. The generator has been developed to simulate and replace the real measurements for the ease of algorithm design and testing, thus avoiding repetitive field measurements. The results show that positioning systems with adequate accuracy can be built with our proposed schemes. We expect that these proposed schemes to be integrated in multitude of systems with context-aware applications, which use location information. Copyright © 2010 John Wiley & Sons, Ltd.

20 citations


Journal ArticleDOI
TL;DR: Akyildiz I. F., 2005, AD HOC NETW, V3, P257; [Anonymous], NASA JPL SENS WEBS P; Basagni S., 1998, 4 ANN ACM IEEE INT C, P76; Blazevic L, 2001, IEEE COMMUN MAG, V39, P166, DOI 10.1109-35.570738.
Abstract: Akyildiz I. F., 2005, AD HOC NETW, V3, P257; [Anonymous], NASA JPL SENS WEBS P; Basagni S., 1998, 4 ANN ACM IEEE INT C, P76; Blazevic L, 2001, IEEE COMMUN MAG, V39, P166, DOI 10.1109-35.925685; Braginsky D., 2002, 1 ACM INT WORKSH WIR, P22, DOI 10.1145-570738.570742; Caruso A, 2005, IEEE INFOCOM SER, P150; Commuri S, 2006, INT J DISTRIB SENS N, V2, P333, DOI 10.1080-15501320600719151; Durocher S, 2008, ICDCN, P546; Flury Roland, 27 ANN IEEE C COMP C; Fonseca R, 2005, 2 S NETW SYST DES IM, P329; Funke S, 2007, IEEE INFOCOM SER, P1244, DOI 10.1109-INFCOM.2007.148; He T., 2003, 9 ANN INT C MOB COMP, P81, DOI DOI 10.1145-938994.938995]; Hong X, 2001, IEEE MIL COMM C MILC; Kao G. S.-C., 2005, P 17 CAN C COMP GEOM, P88; Karp B., 2000, 6 ANN INT C MOB COMP, P243; Kim Y., 2004, ACM SIGMOBILE MOBILE, V8, P48, DOI 10.1145-980159.980168; Kim Y-J, 2005, 2 S NETW SYST DES IM, P217; Kranakis E., 1999, 11 CAN C COMP GEOM, P51; Kuhn F, 2003, 4 ACM INT S MOB AD H; Li J., 2000, 6 ANN ACM IEEE INT C, P120; Liang B, 2006, USENIX S NETW SYST D; Ma C, 2006, MOBILE NETW APPL, V11, P757, DOI 10.1007-s11036-006-7800-2; Mauve M, 2001, IEEE NETWORK, V15, P30, DOI 10.1109-65.967595; Moscibroda T, 2004, ACM JOINT WORKSH FDN; Perkins C. E., 1994, SIGCOMM, P234; Perkins C. E., 1999, Proceedings WMCSA'99. Second IEEE Workshop on Mobile Computing Systems and Applications, DOI 10.1109-MCSA.1999.749281; Ren Z, 2005, IEEE INT C MECH AUT, P2222; Rao R, 2003, COMPUTER, V36, P77, DOI 10.1109-MC.2003.1250886; Witt M, 2006, INT C WIR MOB COMM J, P76

15 citations


Journal ArticleDOI
TL;DR: This work studies the energy cost of key agreement protocols between peers in a network using asymmetric key cryptography and finds that an intensive computational primitive for resource-constrained devices, such as non-interactive identity-based authenticated key exchange, performs comparably or even better than traditional authenticatedKey Exchange (AKE) in a variety of scenarios.
Abstract: Wireless sensors are battery-powered devices which are highly constrained in terms of computational capabilities, memory and communication bandwidth. While battery life is their main limitation, they require considerable energy to communicate data. Due to this, it turns out that the energy saving of computationally inexpensive primitives (like symmetric key cryptography (SKC)) can be nullified by the bigger amount of data they require to be sent. In this work, we study the energy cost of key agreement protocols between peers in a network using asymmetric key cryptography. Our main concern is to reduce the amount of data to be exchanged, which can be done by using special cryptographic paradigms like identity-based and self-certified cryptography. The main news is that an intensive computational primitive for resource-constrained devices, such as non-interactive identity-based authenticated key exchange, performs comparably or even better than traditional authenticated key exchange (AKE) in a variety of scenarios. Moreover, protocols based in this primitive can provide better security properties in real deployments than other simple protocols based on symmetric cryptography. Our findings illustrate to what extent the latest implementation advancements push the efficiency boundaries of public key cryptography (PKC) in wireless sensor networks (WSNs). Copyright © 2010 John Wiley & Sons, Ltd.

15 citations


Journal ArticleDOI
Shiow-Fen Hwang1, Kun-Hsien Lu1, Yi-Yu Su1, Chi-Sen Hsien1, Chyi-Ren Dow1 
TL;DR: This work presents a grid-based hierarchical multicast (HM) routing protocol for WSNs with mobile sinks and demonstrates that the proposed protocol has a lower energy consumption and higher multicast efficiency than distributed multicast routing protocol (DMRP) and hierarchical geographic multicasts routing (HGMR), especially when many sources and receivers are involved.
Abstract: In most studies of wireless sensor networks (WSNs), sensor nodes and sinks are typically stationary. However, mobile sinks are required in various applications of real-life environments, and delivering sensed data to mobile sinks using ordinary routing protocols is very inefficient. Multicasting is an important process in the minimization of the number of transmissions in WSNs. Since sensor nodes have limited resources, many studies have focused on how to send data to specific receivers efficiently. This work presents a grid-based hierarchical multicast (HM) routing protocol for WSNs with mobile sinks. Location servers (LSs) are adopted to manage the information about the locations of receivers and then a multicast tree is constructed distributively to reduce the update cost and energy consumed by sink mobility. The multicast tree can be shared by multiple sources, reducing the path construction overhead. Furthermore, effective maintenance mechanisms that make the multicast tree more stable and robust are presented. Finally, the performance of the proposed HM is investigated by simulation. Simulation results demonstrate that the proposed protocol has a lower energy consumption and higher multicast efficiency than distributed multicast routing protocol (DMRP) and hierarchical geographic multicast routing (HGMR), especially when many sources and receivers are involved. Copyright © 2010 John Wiley & Sons, Ltd.

7 citations


Journal ArticleDOI
TL;DR: A link layer protocol and link-state routing protocol suite for multi-channel ad hoc networks that addresses several practical issues that arise when nodes equipped with two radio interfaces want to utilize available channels.
Abstract: We propose a link layer protocol and link-state routing protocol suite for multi-channel ad hoc networks. The proposed protocol suite addresses several practical issues that arise when nodes equipped with two radio interfaces want to utilize available channels. The routing layer makes a hybrid channel assignment where one interface is fixed and the other is switchable. Based on that, the routing layer runs a shortest path routing algorithm augmented with channel diversity. The link layer implements a slotted structure to minimize broadcast overhead inherent to multi-channel networks. By using flow- and packet-level simulators, we make some important observations. First, a hybrid channel assignment is good for connectivity and amenable to shortest-path routing. Second, seeking a shortest-path can be a better routing strategy in terms of global system throughput than complex channel-diverse routing. Third, channel switching delay is not a throttling factor in terms of global system throughput. Copyright © 2010 John Wiley & Sons, Ltd.

6 citations


Journal ArticleDOI
TL;DR: A new routing algorithm for mobile ad hoc networks that uses the residual battery capacity, transmission power, and hop-count to route the data packet.
Abstract: If the battery of a node is drained out, then it cannot be communicated with other nodes and the number of dead-nodes makes the network partition. In order to overcome this problem, we propose a new routing algorithm for mobile ad hoc networks. It uses the residual battery capacity, transmission power, and hop-count to route the data packet. Here the proposed model has simulated with the help of 100 mobile nodes using the network simulator and has tested under various conditions. It compares with the ad hoc on-demand distance vector protocol, minimum total transmission power, and min–max battery cost routing models. The proposed model has shown better results in terms of node lifetime and network lifetime. The mobile nodes start to die at 400, 420, 440, 470, and 508 s for AODV, MTPR, MMBCR, CMMBCR, and proposed models, respectively. If the system has 145 J, then the AODV model transmits 38 000 of data packets, whereas the MTPR, MMBCR, CMMBCR, and proposed models will transmit 37 600, 47 240, 41 580, 42 700, and 42 955 of data packets, respectively. Copyright © 2009 John Wiley & Sons, Ltd.

5 citations


Journal ArticleDOI
TL;DR: An overview of distributed inference for both wearable and ambient sensing with specific focus on graphical models—illustrating their ability to be mapped to the topology of a physical network is provided.
Abstract: Wireless sensor networks enable continuous and reliable data acquisition for real-time monitoring in a variety of application areas. Due to the large amount of data collected and the potential complexity of emergent patterns, scalable and distributed reasoning is preferable when compared to centralised inference as this allows network wide decisions to be reached robustly without specific reliance on particular network components. In this paper, we provide an overview of distributed inference for both wearable and ambient sensing with specific focus on graphical models—illustrating their ability to be mapped to the topology of a physical network. Examples of research conducted by the authors in the use of ambient and wearable sensors are provided, demonstrating the possibility for distributed, real-time activity monitoring within a home healthcare environment. Copyright © 2010 John Wiley & Sons, Ltd.

3 citations


Journal ArticleDOI
TL;DR: Experimental results indicate that DynaChannAl successfully distributes multi-ple (mobile) source nodes on multiple wireless channels and enables the nodest to select wireless channel and links that can minimize the end-to-end latency.
Abstract: With recent advances in wireless communication, networking, and low powersensor technology, wireless sensor network (WSN) systems have begun to takesigni cant roles in various applications ranging from environmental sensing tomobile healthcare sensing. While some WSN applications only require a lim-ited amount of bandwidth, new emerging applications operate with a notice-ably large amount of data transfers. One way to deal with such applicationsis to maximize the available capacity by utilizing the use of multiple wirelesschannels. This work proposes DynaChannAl, a distributed dynamic wirelesschannel algorithm with the goal of e ectively distributing nodes on multiplewireless channels in WSN systems. Speci cally, DynaChannAl targets applica-tions where mobile nodes connect to a pre-existing wireless backbone and takesthe expected end-to-end queuing delay as its core metric. We use the link qual-ity indicator (LQI) values provided by IEEE 802.15.4 radios white-list potentiallinks with good link quality and evaluate such links with the aggregated packettransmission latency at each hop. Our approach is useful for applications thatrequire minimal end-to-end delay (i.e., healthcare applications). DynaChannAlis a light weight and highly adoptable scheme that can be easily incorporatedwith various pre-developed components and pre-deployed applications. We eval-uate DynaChannAl in on a 45 node WSN testbed. As the rst study to considerend-to-end latency as the core metric for channel allocation in WSN systems, theexperimental results indicate that DynaChannAl successfully distributes multi-ple (mobile) source nodes on di erent wireless channels and enables the nodesto select wireless channel and links that can minimize the end-to-end latency.Keywords: Wireless Sensor Networks, Dynamic Channel Allocation, LatencyAware Protocols

2 citations


Journal ArticleDOI
TL;DR: Simulation results show the effectiveness and efficiency of the BLD protocol and its robustness to localization errors and transmission errors.
Abstract: Broadcast is a fundamental operation in wireless ad hoc and sensor networks This paper proposes a simple and efficient broadcast protocol, called Broadcast based on Layered Diffusion (BLD), which is a stateless broadcast protocol with very low message overheads and very low computation requirements In BLD, nodes do not need to exchange neighborhood information for building a broadcast backbone, but make their rebroadcast decisions locally The design idea of BLD is to emulate the triangular tessellation for complete area coverage of the network field It does not require nodes' location information for such tessellation emulation but only exploits the hop count information for each node to make local rebroadcast decision and timing Simulation results show the effectiveness and efficiency of the BLD protocol and its robustness to localization errors and transmission errors Copyright © 2009 John Wiley & Sons, Ltd