Improving Routing in Sensor Improving Routing in Sensor Networks with Heterogeneous Networks with Heterogeneous Sensor NodesSensor Nodes

Xiaojiang Du & Fengjing Lin

Vehicular Technology Conference,2005 Spring,Volume 4

OutlineOutline

• Motivation

• Cluster Head Relay Routing Protocol– Cluster Formation– Intra-Cluster Routing– Inter-Cluster Routing

• Performance

• Conclusion

MotivationMotivation

• A homogeneous sensor network suffers from poor performance limit and scalability.

• In homogeneous sensor networks, all sensor nodes have the same capabilities in terms of communication, computation, energy supply, reliability etc.

Cluster Head Relay Routing ProtocolCluster Head Relay Routing Protocol

• Heterogeneous sensor networks with two types of nodes: a small number of powerful High-end sensors (H-sensors) and a large number of Low-end sensors (L-sensors).

• Cluster is formed around each H-sensor.

Cluster FormationCluster Formation

• All H-sensors broadcast Hello messages to nearby L-sensors with a random delay.

• The Hello message includes the ID and location of the H-sensor.

• Each L-sensor will select the closest H-sensor as the cluster head, and this leads to the formation of Voronoi diagram.

Cluster FormationCluster Formation

H-sensor

L-sensor

sink

Intra-Cluster RoutingIntra-Cluster Routing• When a L-sensor sends data to the cluster head

for the first time, it uses a greedy geographic routing protocol (e.g., GPSR), and its location is included in the data packet.

• If a L-sensor does not have any data to send or forward after T seconds of deployment, it will send a specific location packet to CH, with its location information included.

Intra-Cluster RoutingIntra-Cluster Routing

• The cluster is divided into several sectors (e.g., 45 degrees for each sector as in Figure 2).

• For each sector, CH first broadcasts a short message indicating the receiving sector, then CH broadcasts a long message including the two routes for each sensor in this sector.

Intra-Cluster RoutingIntra-Cluster Routing

Inter-Cluster RoutingInter-Cluster Routing

• When a cluster head wants to send data packets to the sink, it draws a straight line L between itself and the sink. Line L intersects with several Voronoi cells (clusters), and these cells are denoted as C0,C1,…,Ck, which are referred to as Relay Cells.

PerformancePerformance

• The default simulation testbed has 4 sinks and 300 sensor nodes randomly distributed in a 300m*300m area.

• For CHR, there are 25 H-sensors and 275 L-sensors.

• Each simulation run lasts for 600 seconds.

• The transmission range of a H-sensor and a L-sensor is 100m and 20m respectively.

PerformancePerformance

PerformancePerformance

ConclusionConclusion

• CHR has higher packet delivery ratio, lower total energy consumption, smaller end-to-end delay and better throughput than two popular sensor network routing protocols – Directed Diffusion and SWR.

• Why cluster divide into several sectors?