ECN B4 : Dao Thanh Chung (bull@ht)Tutor : Takatoshi Kanazawa (takatosi@ht)

fNode : Reducing Network Packet Transmission Overhead in Indoor

Heterogeneous Wireless Sensor Networks

Graduation Thesis Final PresentationTokuda Lab

BACKGROUND Traditional WSN deployment

Because of cost and complexity of node deployment, network deployment using a single sensor node hardware platform

Narrow monitoring Sensing ability: either temperature, humidity or fire

Heterogeneous wireless sensor network Consist of sensor nodes with different capabilities

Radio frequency, Sensing range, Hardware platform Wide monitoring

Temperature, humidity, fire, sound, etc.

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenterRedundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 5

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 56

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 56

１

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 56

１ 2

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 56

１ 2 3

PROBLEM DEFINITION Heterogeneous sensor nodes are required to be

deployed under the same environment Sensor nodes with different hardware platforms

cannot communicate with each other →　 Redundant Packet Transmission Overhead

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１Redundancy Data

Black node in the hall needs many hops (6 hops)Fire sensorTemperature sensor

2

3 4 56

１ 2 3

4

PACKET TRANSMISSION OVERHEAD Experiments with 8 sensor nodes in classroom

environmentSend packets from the first node to 8th node

Increase power consumption and delay time when the number of hops rise

Consumed Power Delay time

Number of hops Number of hops

PROPOSED SOLUTION Propose fNode

Act as an intermediate node for packet forwarding

Replace redundant forwarding nodes Convert and forward packet’s format compatible

with various platforms Propose fMap Algorithm

Minimize the network packet transmission overhead Require an ideal deployment scenario of fNode

fMap algorithm estimates fNode’s positions

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenter

１

２

３ ４ ５６

Redundancy Data

Black node’s packets in the hall are transmitted by a shorter path via fNode (3 hops)

FNODE DEPLOYMENT SCENARIO

WC

HallRoom Room

Room

RoomRoom

conference room

conference room WC

Plant SinkCenterfNode

１2 3

DESIGN OF FNODE

Receive packets Convert the packet’s format Transmit converted packets

Micro Controller

A Radio Module

A Radio Module

B Radio Module

B Radio Module

Incoming packets Outgoing packets

A packets

B packets A packets

B packets

FMAP ALGORITHM

Original Topology

Forwarding node

Fire sensor

Temperature sensor

FMAP ALGORITHM

Remove all forwarding nodes

FMAP ALGORITHM

Topology after one fNode added(Find fNode position by reviewing all deployable positions)

FMAP ALGORITHM

Topology after 2nd fNode addedAll nodes are connected → stop loop

IMPLEMENTATION In order to evaluate packet

transmission overhead Design fNode testbed

fNode testbed A laptop Sensor nodes are connected

We provide a GUI to implement fMap Java language

Sun Spot nodeIris node

Converting packets

fMap GUI

EVALUATION ENVIRONMENT Classroom environment (20m x 30m with minor radio

blocking obstacles such as desks and chairs) 2 Macbook Pro as fNode testbeds SunSpot and Iris nodes as sensor devices

7 SunSpot nodes 6 Iris motes

Deploy sensor nodes with two topologies: linear and hybrid

SunSpot node Iris mote Classroom

TESTBED TOPOLOGY Linear topology

Non-overlapping sensing regions

Hybrid topology Overlapping

sensing regions Experimental

assumption Same MTU Cover range: 5m Minor radio

blocking obstacles No wave noise

EVALUATION METHOD Deploy the sensor nodes and a sink node

with the linear and hybrid topologies 7 SunSpot and 6 Iris nodes Deploy at arbitrary positions

Measure the sum of hops, the power usage and the packet transmission latency of each node that is necessary to transmit its packets to the sink node Average of 20 times measurement

Use fMap to calculate positions of fNodes and deploy fNodes with existing sensor nodes, and perform the same measurement as above

EXPERIMENTAL RESULTS Total number of transmitted packets

Reduced by approximately 30%

Linear Topology• 24 hops (Original) vs. 18 hops

(Using fNode): 6 hops decreased Hybrid Topology

• 30 hops (Original) vs. 20 hops (Using fNode): 10 hops decreased

POWER CONSUMPTION RESULT

Transmission Power – reduced 33-39%

Linear Topology• 688 mA (Original) vs. 448 mA

(Using fNode): decreased by 33% Hybrid Topology

• 875 mA (Original) vs. 531 mA (Using fNode): decreased by 39%

fNode’s Power comsumption = (SunSpot + Iris)/2

LATENCY RESULT

Delay time – reduced 35-50%

Linear Topology• 381 ms (Original) vs. 167 ms

(Using fNode): decreased by 50% Hybrid Topology

• 386 ms (Original) vs. 251 mA (Using fNode): decreased by 35%

Linear (50%) vs. Hybrid (35%)• Delay time

• SunSpot : 23ms• Iris mote: 4ms

• Linear relays via Iris mote more than Hybrid does

RELATED WORK A Framework for Flexible Packet Processing in

Heterogeneous Sensor Networks (M. Leogrande, C. Pastrone… at FGCN 07) Base on XML language Flexible packet processing Increase in flexibility, adaptability and extensibility However, it only focuses on processing messages Packet transmission overhead is still unsolved

Adaptive Online Energy Saving for Heterogeneous sensor networks (Qiu, J. Hu, E. Sha,at 19th IASTED ) Base on time interval Obtain the best mode assignment for each node Adjust online However, availability of WSN is decreased

CONCLUSION AND FUTURE WORK Propose fNode

Forward packets of different communication architecture

Packet transmission overhead, power usage and latency Reduced approximately 30%

Application areas Building management system Greenhouse management system

Evaluate the benefit of fNode is only the first step Our future work

Implement a realistic fNode Deploy under a larger scale WSN