Search

SUMMARY In large-scale wireless sensor networks, in order to support group mobility of mobile sinks, this letter proposes a novel strategy for energy-efficient and robust data dissemination to the sinks based on cluster-based communication. The novel strategy is composed of two major mechanisms for reduction of structure construction overhead and routing state maintenance overhead: 1) a virtual infrastructure construction through grid-referred clustering and 2) inter-cluster communication by geographic routing relying on recursive location search. Based on the two major mechanisms, the strategy provides representative location management per sink group, distributed data collection, and per-cluster foot-print chaining in order to effectively adapt the traditional strategy for individual mobile sinks. Simulation results prove the proposed strategy shows better performances

In Proxy Mobile IPv6 (PMIPv6), when a Mobile Node (MN) enters a PMIPv6 domain and attaches to an access link, the router on the access link detects attachment of the MN by the link-layer access. All elements of PMIPv6 including the router then provide network-based mobility management service for the MN. If the MN moves to another router in this PMIPv6 domain, the new router emulates attachment to the previous router by providing same network prefix to the MN. In other words, PMIPv6 provides rapid mobility management based on layer-2 attachment and transparent mobility support to the MN by emulating layer-3 attachment with respect to intra-domain roaming. However, when the MN moves to other PMIPv6 domains, although the domains also provide the network-based mobility management service, the MN should exploit the host-based mobility management protocol, i.e. Mobile IPv6 (MIPv6), for the inter-domain roaming. Hence, this letter proposes the rapid and transparent inter-domain roaming mechanism controlled by the networks adopting PMIPv6.

In wireless sensor networks, studies in terms of data dissemination to individual mobile sinks traditionally rely on a strategy that consists of a virtual infrastructure to service current location of the sinks and per-sink foot-print chaining to support local mobility after location update. To adapt the strategy for supporting mobile sink groups, it might be simply considered to use a representative per a sink group in order to representatively update location and representatively make a foot-print chain. However, it may lead to considerable problems with respect to efficiency and robustness for data dissemination: inefficient data collection problem, intra-group location update problem, and relay path loss problem. In this letter, we propose a novel strategy for data dissemination decoupled with any member sink of a mobile sink group. In order to independently deal with a mobile sink group, the strategy is composed of three mechanisms: representative location update, distributed data collection, and per-group foot-print chaining.

Typical Information communication for large-scale wireless sensor networks may be performed in a data-centric routing manner. The data-centric routing manner well matches the publish/subscribe communication paradigm operated by a contention-based networking. The publish/subscribe paradigm provides decoupling properties for data-centric networking: space, time, and synchronization decoupling. For large-scale applications in which many publishers and subscribers are participated in interworking of information, the decoupling properties proffer salability. However, most existing communication schemes for the large-scale sensor networks do not fully satisfy the decoupling properties. The schemes construct network structures based on publishers or subscribers known as event sources and sinks respectively. Such dependency of network structures causes that network structures are established in proportion to the number of sinks or sources, i.e. space dependency. Also, originating sinks or sources of structures are always joined with the structures and manage the interworking information, i.e. dependency of time and synchronization. Hence, the communication schemes should take into account a network structure independent of the publishers and subscribers. In this paper, we propose a novel communication scheme decoupled with sinks and event sources, called ARBITER. ARBITER constructs a shared virtual grid with level value k from center point, k = 0. It then arranges storage nodes and transit nodes at level 1 cross points and over level points respectively. Sinks query to the storage nodes through the transit nodes and receive interesting information via requesting paths. Sources store sensed data to the storage nodes by the transit nodes. Our simulation proves that ARBITER shows better performance in terms of scalability, data responsibility, and mobility support.

In large scale internet network, the research in area of event detection and report publish/subscribe communications paradigm is being progressed. Data-centric is the basic characteristic of data transmission mode of the publish/subscribe communications paradigm. Such characteristic coincides with the wireless sensor network. The publish/subscribe communications paradigm performs task in manner of space, time and synchronous decoupling. The publish/subscribe communications paradigm with such property is tend to be applied to the wireless sensor network. However, existing algorithms do not satisfy the three decoupling modes in wireless sensor network. Therefore, this paper applies the publish/subscribe communications paradigm to the wireless sensor network and proposes a model to solve the energy consumption problem. The proposed communication model satisfies the three decoupling modes by using Embedded Grid Structure (EGS) in the wireless sensor network. Simulation results show that proposed model is energy-efficient compared with other protocols.

In many sensor applications such as intruder tracking, reliable data dissemination is necessary. Existing studies in ad hoc networks generally apply end-to-end control for reliability. This approach however could not adapt to wireless sensor networks (WSNs). Existing studies in WSNs generally apply multi-path approach for reliability. This approach however only increases probability but could not assure data dissemination. In typical WSNs, data are delivered from a source node to a destination node on routing path that is fixed within a certain period of time. This routing path is well-matched with notion of virtual circuit. Approaches based on virtual circuit traditionally use hop-by-hop control for reliable data dissemination. In this paper, we apply notion of virtual circuit to WSNs and propose hop-by-hop control for reliable data dissemination. The proposed scheme consists of three major functionalities: virtual circuit construction, hop-by-hop control, and virtual circuit management. Virtual circuit construction make sure constructing fixed routing path by routing table. Hop-by-hop control guarantees data transmission between two nodes, i.e. one hop, on virtual circuit by error detection and retransmission. Virtual circuit management prevents disconnecting circuit by reconstructing circuit. Simulation results show that the proposed scheme is efficient in terms of data delivery ratio and energy consumption.

Typical multicasting saves efficiently both bandwidth and energy in static wireless sensor networks. Such benefits make the research of multicast which is a transmission from a data source to multiple destinations (sinks), actively. Most of these researches focused on the way how to make efficient multicast tree only, they are weak for supporting mobile sinks. In practical applications, sinks move around and collect information from a sensor field. If the mobile sinks apply to these approaches, frequent entire multicast tree reconstructions are needed to support mobile sinks. Unfortunately, it leads to exhaustion of sensors' limited power supply, consequently it reduces whole network lifetime. In this paper, we propose an energy-efficient multicast protocol to support multiple mobile sinks by the local multicast tree reconstruction, called Local Updated-based geographic Multicasting for Mobile sinks (LUMM) for wireless sensor networks. A value of BOD (benefit of distance) used a standard from a local multicast tree reconstruction with minimal overhead. Our simulation results show that LUMM support the mobility of sinks efficiently.

In delay-tolerant wireless sensor networks, reporting data from a source node to a sink may be delayed to satisfy certain criterions, for example, high energy-efficiency, low algorithm complexity and so on. Sensed data in such networks accumulate on a sensor node during time delayed. It means that even a single failed node may cause a massive-data loss. This paper proposes a backup scheme to minimize data losses caused by failed nodes in wireless sensor networks using the delayed report. The proposed scheme can safely preserve data and consume less energy by backuping a single data to multiple nodes that exist in the one-hop distance from the source node. Multiple backup nodes do not only store and recover backup data but also distributedly report their backup data to the sink instead of the source node. As a result, the energy consumption for data report is not concentrated to the source node and is distributed to backup nodes. Such approach suggests the new potentiality of a backup scheme in error-scarce network.

In wireless sensor networks, groups of mobile users interested in equivalent information could be classified into two categories according to existence of direct communication channel among the users: 1) loosely coupled user group and 2) tightly coupled user group. The loosely coupled group means that a mobile user should communicate with others via a wireless sensor network for querying, gathering, and sharing of information interested from the group. Several information communication mechanisms have already been proposed to support mobility of the loosely coupled user groups. However, the mechanisms may not suit in case of sensor applications with multiple data sources since those are usually construct a network structure per each source. Namely, according to the mechanisms, too many network structures for the many data sources could be constructed and it may causes excessive computing overhead and energy exhaustion of sensors. Therefore, we propose an information communication mechanism to support mobility of loosely coupled mobile users in sensor applications with multiple sources. First, we examine the problems for mobility support of the loosely coupled groups in wireless sensor networks with multiple source nodes, and then study the dynamic sink communication model for data gathering from multiple sources and data delivery to a mobile user. Finally, we present an energyefficient solution to support mobility of loosely coupled groups based on data gathering tree establishment via distributed manner and tree-based data multicasting.

We propose a communication mechanism to support mobility of loosely coupled mobile users in sensor applications with multiple sources. First, we examine problems for mobility support of the loosely coupled users in wireless sensor networks with multiple source nodes, and then study the dynamic sink communication model to support a mobile user with sink-oriented tree based data gathering from multiple sources and data-centric unicasting. Finally, we present an energy-efficient solution to support the loosely coupled mobile users through single data-gathering tree establishment with a distributed manner and the gathering tree based data-centric multicasting.

Most existing geographic routing protocols on sensor networks concentrates on finding ways to guarantee data forwarding from the source to the destination, and not many protocols have been done on collecting and aggregating data of sources in a local and adjacent region. However, data generated from the sources in the local and adjacent region are often redundant and highly correlated. Accordingly, data collection and aggregation of the region in the sensor networks is important and necessary to save the energy of sensor nodes. We introduce the concept of a local sink to address this issue in geographic routing. The local sink is a sensor node in the region, in which the sensor node is temporarily selected by the global sink for collecting and aggregating data from source nodes in the region and delivering the aggregated data to the global sink, in geographic routing. We also design a model to determine an optimal location of the local sink and propose a mechanism to collect data through the local sink. Simulation results show that the proposed mechanism with the local sink is more efficient in terms of the energy and the data delivery ratio than the existing mechanism in a geographic routing.

In wireless sensor networks, existing location- based multicast protocols deliver data packets to group members through static data paths, using the location information of group members. Routing paths in the data delivery paths are never changed unless topology changes. Therefore, the nodes on the routing paths can be dead owing to continuous energy consumption and thus the lifetime of network might be shortened. This paper proposes a dynamic location-based multicast protocol to balance the network energy consumption by changing the routing paths so that prolong the lifetime of wireless sensor networks. Finally, we prove performance improvement of our protocol on energy consumption by using simulations.

Geographic routing has been considered as an efficient, simple, and scalable routing protocol for wireless sensor networks since it exploits pure local location information instead of global topology information to route data packets. Geographic routing requires the sources nodes to be aware of the location of sinks. Most existing geographic routing protocols merely assume that source nodes are aware of the location of sinks or can get the location of sinks by some service. How can source nodes get the location of sinks was not addressed in detail. In this paper, we propose an efficient sink location acquirement scheme for geographic routing in wireless sensor networks. Simulation results show that our protocol is significantly superior to other protocols in terms of energy consumption and control overhead.

Many researches in wireless sensor networks have been exploited a geographic routing to effectively disseminate data between sinks and sources. However, the geographic routing needs that the sinks and the sources are aware of location information of each other. To know the location information, there have been proposed two manners. The first manner is a sink-initiated location information flooding that the sink floods its location information. The second manner is a source-initiated location information flooding that the source floods its location information. However, these two manners have two problems. Firstly, whenever the sink and the source move, they flood their location information. Secondly, in few sinks and few sources, their location information is disseminated unnecessary nodes besides nodes which send and receive data in actually. Therefore, this paper proposes a protocol that can solve the two problems and disseminate effectively data between few sinks and few sources. The proposed protocol exploits a location information manager that manages real-time location information of the sinks and the sources. We also compare the performance of the proposed protocol with the existing protocols through a simulation, and show the superiority of the proposed protocol in terms of network lifetime, data delivery ratio, and delay latency.

Most existing routing protocols on the object detection and tracking in sensor networks concentrates on finding ways to detect and track one or more individual objects, such as people, animals, and vehicles, and not many protocols have been done on detecting and tracking continuous objects, such as poison gas, biochemical, and chemical liquid. These continuous objects are quite different from the individual objects in that they continuously distributed across a region and usually occupy a large area. Accordingly, they are detected and sensed by many sensor nodes, and their sensing data are redundant and highly correlated. Hence, there need any efficient scheme on collecting and aggregating locally their sensing data and generating the data report. The continuous objects also tend to diffuse, changes in shape, increases the size, even splits into multiple smaller continuous objects, or join together one continuous object. Accordingly, there also need any efficient scheme to manage efficiently the dynamic change of shape of the continuous objects. Therefore, we introduce dynamic rectangle zone-based collaboration mechanism for detecting, tracking, and monitoring the continuous objects taking into account their properties. One center node in the zone collects and aggregates the sensing data from sensor nodes which detect the continuous object. The dynamic rectangle zone change newly according to dynamic change of the continuous object and the center node is also altered by another node to minimize the energy consumption for collecting the sensing data.

Geographic routing has been considered as an energy efficient and simple routing protocol for wireless sensor networks. It utilizes only geographical location information without global network structures to route data packets. To take these advantages of geographic routing, a source node should be aware of the location of a sink node. Methods that the source node efficiently obtains the sink location information, however, have been scantily studied yet. In this paper, we propose a restricted linear flooding scheme to obtain sink location in wireless sensor networks. The source node sends location query message and the sink node sends location announcement message to specified direction respectively. The node located on a crossing point of these two message forwarding paths informs the source node about the sink location information. Then the source node sends data to the sink node by geographic routing. The proposed scheme also constructs a virtual restricted linear flooding zone inside the network to guarantee the existence of the crossing point. Simulation results show that proposed scheme is more efficient in terms of energy consumption than existing protocols.

Void areas (holes) as an inevitable phenomenon exist in geographic routing of wireless sensor networks, because the unpredictable and harsh nature application environment or uneven energy consumption. Most of the existing schemes for the issue tend to construct a static detour path to bypass a hole. The static detour path may lead to uneven energy consumption of the nodes on the perimeter of the hole; thus it may enlarge the hole. At the same time, traffic would concentrate on the peripheral node of the hole; thus the nodes on the perimeter of the hole tend to be depleted quickly. In previous work, we have proposed a hole geometric model to reduce the energy consumption and packet collisions of the nodes on the hole boundary. This scheme, however, still has the static detour path problem. Therefore, we extend the previous work by constructing a dynamic detour path hole geometric model for wireless sensor networks in this paper. The location of hole detour anchor is dynamically shifted according to Gaussian function, just generating dynamic hole detour paths.

Many dissemination protocols on the mobility support in wireless sensor networks have been designed based on the assumption that the movement trace of sinks is random. However, the mobility of the sinks in many applications, for example, the movement traces of a soldier on operation in a battle field or a firelight on rescue operation in the disaster area, can be determined in advance since they move in accordance with the decided operation or the drill regulation to perform their task. In this paper, we propose a Predictable Mobility-based Data Dissemination protocol (PMDD) that enables data to directly route from source nodes to moving sinks by taking into consideration predictable movement behavior of the sinks. We also compare the performance of the PMDD with those of other dissemination protocols with random movement behavior of the sinks, and show the superiority of the PMDD based on network lifetime, data delivery ratio, and delay latency.

Sensor networks are composed of a great number of sensor nodes. Since all sensor nodes are energy-restricted and hard to recharge, it is very important. However, the energy consumption may significantly increase if mobile sources or sinks exist in sensor networks. The reason is that the routing information for mobile sources and sinks needs to be update frequently for efficient data delivery. The routing algorithm supporting mobile sinks should consider not only continuous data delivery but also the energy consumption of sensor nodes. However, most of the existing research e.g. Fan Ye, et al. (Set. 2002), Zehua Zhou, et al., (Jun 2006) focuses on even energy consumption while the mobility of sinks and sources is rarely consider. In this paper, we propose an efficient routing protocol with multiple virtual grids to reduce energy consumption and improve packets delivery efficiency. Simulation results show that our algorithm can guarantee high data delivery ratio and lower average delivery delay, while consuming lower energy than existing routing protocols in sensor networks.

Sensor networks are composed of a great number of sensor nodes. Since all sensor nodes are energy-restricted and hardly to recharge. So in order to prolong network life, it is very important to minimize energy consumption. However, the energy consumption may significantly increase if mobile sources or sinks exist in sensor networks. The reason is that the routing information for mobile sources and sinks needs to be update frequently for efferent data delivery. The routing algorithm supporting mobile sinks should consider not only continuous data delivery but also the energy consumption of sensor nodes. However, most of existing research e.g. [2, 3] focuses on even energy consumption while rarely considers the mobility of sinks and sources. In this paper, we propose an efficient routing protocol with multiple virtual grid to reduce energy consumption and improve packets delivery efficiency. Simulation results show that our algorithm can guarantee high data delivery ratio and low average delivery delay, while consumes lower energy then existing routing protocols in sensor networks.

Overlay multicast protocols in mobile ad hoc networks (MANET) have advantages that are low overhead and robustness in dynamic network topology by using the unicast routing protocol between group members. However, overlay data paths in overlay multicast can remain static even though the underlying physical topology is changing. Overlay multicast may lead to sub-optimal overlay data paths, since the communicating group members are not aware of the underlying physical topology. Therefore, overlay multicast protocols requires periodic control messages for the overlay data path management in dynamic environment. In this paper, we propose an efficient overlay multicast protocol (EOMP) using unicast routing information. Multicast state information of each group member in EOMP is created by its unicast routing table. Therefore, multicast data packets between group members are delivered through the overall optimal paths in physical networks. Meanwhile, the overlay data path in EOMP can be managed without periodic control messages in the dynamic environment. Finally, we evaluate EOMP performance with other multicast protocols proposed for ad hoc networks. Simulations show enhanced results of proposed protocols.

Typical sensor networks consist of users, sinks, and a number of sensor nodes. The traditional architecture usually assumes that there is a legacy network between users and sinks. However, practical users like firefighters and soldiers move around sensor fields and they might not have any direct communication through legacy networks. In other words, sensor networks are the only communication channel between users and sinks in practical sensor fields. Now there are no researches with respect to architecture to support the user mobility. Thus it is necessary to deliberate a new architecture for such the issue. In this paper, we present a novel communication architecture where a user operates around an infrastructureless sensor field. We, then, propose a new networking model, named dynamic sink model, to support user mobility on the novel architecture. In the model a sink is temporarily selected among generic sensor nodes by a user when the user wants to get information from a sensor network. The chosen sink gathers data from sensor nodes for interested tasks and propagates collected information to the user via the sensor network. We evaluate and explore performance of the dynamic sink model on the novel architecture with regard to average delay, delivery ratio, and network lifetime compared with the common static sink model on typical communication architecture.

Geographic routing has been considered as an efficient, simple, and scalable routing protocol for wireless sensor networks since it exploits pure location information instead of global topology information to route data packets. Geographic routing requires the sources nodes to be aware of the location of the sinks. How can source nodes get sinks locations with low overhead is a difficult issue in wireless sensor networks. In this paper, we propose a Sink Location Service for geographic routing in wireless Sensor Networks. In this scheme, a source node and a sink node send sink location announcement and query messages along two paths respectively by geographic routing. The node located on the crossing point of the two paths informs the source about the sink location. Then the source can send data packet to the sink by geographic routing. How to guarantee that these two paths have at least one crossing point in any irregular profile of sensor network is the challenge of this paper. Simulation results show that our protocol is significantly superior to other protocols in terms of energy consumption and control overhead.