Energy Saving In Sensor Network Using Specialized Nodes Shahab Salehi EE 695

What is a Sensor Network Small wireless nodes Functionality Detect events Relay information to the Base Station Applications: monitoring of wildlife, intruders, earthquakes, fire, contaminants etc.

Issues Number of nodes In the range of Millions In the range of Millions Need to configure themselves automatically once deployed No Infrastructure Power Consumption

Power Consumption Problem Once the nodes are deployed, it is not an option to change the battery Environment Environment Cost Cost Number of nodes deployed Number of nodes deployed Important to be able to save as much energy as possible

Nature Of Network Sensor They are usually application specific Event driven Event driven Time driven Time driven Can use this as an advantage to minimize power consumption Sampling Temperature every 1 min. Sampling Temperature every 1 min. Network does not need to send data unless an even has occurred Network does not need to send data unless an even has occurred

Energy Saving Methods Using energy efficient routing protocols Advantages Advantages Used with existing hardware Can find the shortest or less costly path Disadvantages Disadvantages Have to come up with a new protocol

Energy Saving Methods (Cont.) Use of processors sleep mode Sleep, wake up every 1 minute, take the temperature, send data, Go back to sleep Sleep, wake up every 1 minute, take the temperature, send data, Go back to sleep Use of external sensors Use of external sensors Processors is sleep, but the sensor is on and detecting events. Processors is sleep, but the sensor is on and detecting events. Sensor uses minimal power, therefore saving power while there is no event Sensor uses minimal power, therefore saving power while there is no event

Energy Saving Methods (Cont.) Dynamic transmission power A B C

Energy Saving Methods (Cont.) Change Transmission power based on SNR A B C

Proposed Method Use of two different type of nodes during deployment Sensor nodes Sensor nodes Larger size Transmitter nodes for data transmission Larger size Transmitter nodes for data transmission Sensor nodes Small mobile devices Small mobile devices Sensing Sensing Event detection Event detection Transmission Transmission

Proposed Method (Cont.) Transmitter nodes Equipped with larger batteries Equipped with larger batteries Have longer transmission range Have longer transmission range Used only for transmitting data to base station Used only for transmitting data to base station Acts as a highway for the stream of data from the Sensor nodes

Proposed Method (Cont.) Advantages Sensor nodes will spend less time transferring other nodes packets Sensor nodes will spend less time transferring other nodes packets Nodes do not need to search for a path to Base Station, just to the nearest Transmitter Node Nodes do not need to search for a path to Base Station, just to the nearest Transmitter Node Speed of transmission increases Speed of transmission increases Instead of going though many small nodes, data will take fewer hops and goes through few larger nodes

Proposed Method (Cont.) Larger nodes forming a path to Base Station BS

Deployment Steps 1.The Nodes are thrown out of the plane 1.Ex. Border Intrusion Detection 2.Base Station Sends a signal to its nearest Transmitter node 1.Giving it a routing number starting from 1 3.From there each Transmitter node identifies its neighbor (s) and if does not have a routing number it will be given one in an increasing order until all transmitter nodes have routing number

Deployment Steps (Cont.) Purpose of the route number is for the transmitter node to know where it needs to send the packets to BS

Deployment Steps (Cont.) Since the placement of the Transmitter nodes are random The distance between the Transmitter nodes could be longer than their range The distance between the Transmitter nodes could be longer than their range Two or more Transmitter nodes are placed very close together and share the same neighbors Two or more Transmitter nodes are placed very close together and share the same neighbors

Deployment Steps (Cont.) If the distance between two Transmitter node is longer than their range They search for a Sensor node that is with in their range and use it as intermediate transmitting stage They search for a Sensor node that is with in their range and use it as intermediate transmitting stage

Deployment Steps (Cont.) If two or more Transmitting nodes share same neighbors One of them on random give a sleep command to their others and will not wake it up until needed One of them on random give a sleep command to their others and will not wake it up until needed

Deployment Steps (Cont.) If at anytime one of the Transmitter node fail or dies, the Sensor nodes will take over its place and try to find the nearest Transmitter node If all the Transmitter nodes die, Sensor node will relay the data using each other

Deployment Steps (Cont.) Optimal number of Transmitter nodes? Length of area being covered Length of area being covered Range of each Transmitter nodes Range of each Transmitter nodes How much redundancy you want How much redundancy you want

Deployment Steps (Cont.) Ex. Border Security 2000,000 m 2000,000 m Range of 100m Range of 100m If the nodes are perfectly setup and operate If the nodes are perfectly setup and operate 2000,000 / 100 = 20,000 Nodes Assume 2/3 of range Assume 2/3 of range 2000,000 / (2/3 * 100) = 30,000 Nodes Redundancy Redundancy 30,000 * 2 = 60,000 Nodes

Conclusion By using Transmitter nodes Add to the life of the network Add to the life of the network Speed up the data collection processes Speed up the data collection processes Faster event notification Can be easily used with other energy saving methods to increase networks life Can be easily used with other energy saving methods to increase networks life

“Simulation” Sensor Node 1 msg / s 1 msg / s Message length 20 bytes, 5 ms to Tx/Rx Message length 20 bytes, 5 ms to Tx/Rx Tx = 0.4 mARx=0.246 mA Tx = 0.4 mARx=0.246 mA Transmitter Node Tx = 0.52 mARx=0.31 mA Tx = 0.52 mARx=0.31 mA BS

“Simulation” Based on Sensor Nodes shortest path 43 hops 43 hops (43 *.4) + (43 *.246) = mA (43 *.4) + (43 *.246) = mA Based on Transmitter Node 2 hops on Sensor Nodes 2 hops on Sensor Nodes 16 hops on Transmitter Nodes 16 hops on Transmitter Nodes (2*.4)+(2*.246)+(16*.52)+(16*.31) = mA (2*.4)+(2*.246)+(16*.52)+(16*.31) = mA

Questions?