Ching-Ju Lin Institute of Networking and Multimedia NTU HCDD : Hierarchical Cluster-based Data Dissemination in Wireless Sensor Networks with Mobile Sink Ching-Ju Lin Institute of Networking and Multimedia NTU Po-Lin Chou Dept. of Computer Science and Information Engineering NTU Cheng-Fu Chou Dept. of Computer Science and Information Engineering NTU ACM International Wireless Communication and Mobile Computing (IWCMC’06)

Outline Introduction Related Work Hierarchical Cluster-based Data Dissemination (HCDD) Cluster Construction Sink Location Registration Data Delivery and Path Routing Performance Evaluation Conclusions

Introduction WSN can be applied to various applications, such as military, surveillance, temperature monitoring. Sensors are randomly scattered to organize a large scale sensor network. Due to the random and inaccessible locations of sensor nodes, the power-consumption of the sensor is the most important consideration.

Introduction Finding a routing path for disseminating data to mobile sinks is a challenging problem. Limited resources, such as energy, storage capacity, and computing capability. Flooding the location information of mobile sink seems to be a naïve method.

Introduction Proposing a Hierarchical Cluster-based Data Dissemination (HCDD) scheme. Sensor nodes are self-organized to find the route without location information. Without any expensive and power-consuming GPS device and with light control overhead.

Introduction Much research has endeavored to develop the routing algorithms, but, however, there are some challenges Globally flooding the sink location cause serious overhead and rapidly exhausted the energy of sensors. Estimating the sensor’s location by GPS device also has heavily power-consumed and impractical. To adjust transmission power to keep connections with the mobile sinks when the sinks are moving out of coverage range is also dissipate much energy.

Introduction This mechanism can reduce the control overhead.

Introduction Part of sensor nodes in the highest level, called Routing Agent. Updating and Recording the Dynamic Global Information for the mobile sink and data source. Other nodes record Static Local Information used to find the routing path to their Routing Agent. Sink information only flooded to the Routing Agent instead of all sensor nodes.

Introduction HCDD can reduce overall control overhead but Routing Agent with heavier traffic load will consume much of their energy. The load of each Routing Agent will be determined by two factors : Number of hierarchical levels. The size of each cluster.

Related Works TTDD : A Two-Tier Data Dissemination Model for Large-scale Wireless Sensor Networks Mobicom 2002

Related Works Record a upstream dissemination node towards the source mobile sink source dissemination node

Immediate dissemination node Related Works Immediate dissemination node Primary Agent mobile sink source dissemination node

Immediate dissemination node Related Works Immediate dissemination node Primary Agent mobile sink source dissemination node

Related Works Advantage Disadvantages Source can effectively deliver data to mobile sinks. Disadvantages Each node should acquire location information by GPS. The grid construction and maintenance per each source leads to a considerable overhead. Some dissemination nodes have high overhead. Some dissemination nodes does not use.

Hierarchical Cluster-based Data Dissemination (HCDD) There are three procedures in HCDD Cluster Construction Sink Location Registration Data Delivery and Path Routing

HCDD – Cluster Construction Group the sensors by Max-Min D-cluster Formation. (INFOCOM 2000) Providing load-balance clustering for extending the life time of sensor network. Each cluster is composed of a CH, several gateways, and ordinary sensors. Each CH maintains the Neighboring Cluster Table, records its neighboring clusters and the set of gateways next to it. Each Routing Agent has Global Information used to communicate with other Routing Agent and records the routing paths for all sensor nodes.

Hierarchical Cluster-based Data Dissemination (HCDD) This mechanism can reduce the control overhead.

HCDD – Sink Location Registration Routing Agent acquire and maintain the information of mobile sink through the sink registration Sink registration is divided into two phases Intra-cluster phase Mobile sink first forwards registration messages and requirements to its corresponding Routing Agent. Inter-cluster phase Routing Agents receives the registration messages in the first phase, will broadcast the information of the mobile sink to all Routing Agent.

HCDD – Sink Location Registration Registration : The dotted line means the intra-cluster registration, and the solid line means the inter-cluster registration

HCDD – Data Delivery and Path Routing After the cluster construction, each sensor node can communicate with Routing Agent along the intra-cluster path A source node delivers data to the sink just has to forward the data to its Routing Agent. Receiving the data from the source node, the Routing Agent can retrieve the sink information and relay data to the sink along the inter-cluster path.

HCDD – Data Delivery and Path Routing Data Delivery : The data source forwards data along the inter-path (dotted lines) and inter-path (solid lines) learned from sink registration

Performance Evaluation and Discussion Number of nodes : 1000 Sensing field : 500m * 500m Buffer size : 10 packets Initial energy : 2.5 Joule Number of source nodes : 20 Data rate of source nodes : 10 packets/sec Transmission range : 28m Moving speed of sink : 10m/sec

Performance Evaluation and Discussion Performance metrics Control overhead Power consumption used for the structure formation and the route maintenance Network lifetime The duration from the beginning of the simulation to the time once one sensor runs out its energy Total number of packets received by the mobile sink Data delivery rate The ratio of packets successfully received by the sink to total packets sent by source nodes.

Performance Evaluation and Discussion Number of sources vs. Overhead

Performance Evaluation and Discussion Number of sources vs. Network lifetime

Performance Evaluation and Discussion Comparison of different schemes

Performance Evaluation and Discussion Cluster size vs. Overhead

Performance Evaluation and Discussion Cluster size vs. Lifetime

Conclusions Proposing an HCDD approach to deal with data dissemination from a number of source nodes to a mobile sink. HCDD exploits a hierarchical cluster-based method to reduce the registration overhead. Simulation shows that the cluster-based method outperforms the grid-based method is not only the longer network lifetime but also lower control overhead. Working efficiently without any location estimation devices, like GPS.