Press button Press button on this node on this node 01 01 01 02 02 02 03 03 03 04 04 04 05 05 05 06 06 06 08 09 08 09 08 09 17 17 17 22 22 22 11 12 11 12 11 12 15 15 15 16 16 16 20 20 20 23 23 23 76 76 76 63 63 07 07 07 24 24 24 10 10 10 13 13 13 14 14 14 18 19 18 19 18 19 21 21 21 25 25 25 Deploy one line Deploy one line Deploy the other line Deploy the other line Make the central Make the central 75 75 75 62 62 until it reaches the first line until it reaches the first line node active node active 26 26 26 61 61 68 74 68 74 85 85 60 60 59 59 65 65 67 67 79 79 80 80 64 64 66 66 77 77 78 78 81 82 81 82 83 84 83 84 27 27 27 58 58 69 69 57 57 56 56 70 70 I nfrastructureless Location Aware 55 55 28 28 71 71 29 29 72 72 54 54 49 49 45 45 42 42 4140 4140 38 38 35 35 34 34 33 33 32 32 73 73 30 30 53 53 52 52 51 51 50 50 48 48 47 47 46 46 44 44 43 43 39 39 36 36 31 31 37 37 Configuration for Sensor Networks Continue to deploy the Continue to deploy the Final Result Final Result Two lines are connected Two lines are connected second line as normal second line as normal Xi Wang joint work with Fabio Silva and John Heidemann Timeout (2 sec) Timeout (1 min) Active Passive University of Southern California, I nformation Sciences I nstitute Receptive (Power On) (Normal) Replied Connection Request 12/ 20/ 2004
I ntroduction Deployment Order I mplementation and Extensions Future Work and Conclusion
Background � Sensor networks � Configuration is important � Network: Ad hoc deployment � Nodes: Numerous, small and inexpensive � Location information is important � Essential environmental parameter � This paper � Deployment order – configuration of (logical) location � Follow-me – a working application Infrastructureless Location Aware Introduction 3 Configuration for Sensor Networks
Follow-Me Application � Motivation - Let’s start from an application � Follow-me: Guide a Destination Destination visitor from point A to point B Visitor follows lights to the destination Visitor follows lights to the destination Entrance Entrance Nodes blink lights to show the path Nodes blink lights to show the path � Our approach Visitor chooses a destination Visitor chooses a destination Visitor Visitor � Sensor nodes are deployed around a building on walls, one at each office doorway � A visitor selects a destination (e.g. using a touch screen) � Nodes blink their lights to indicate a path, guiding a visitor with a “breadcrumb trail” to the destination Infrastructureless Location Aware Introduction 4 Configuration for Sensor Networks
Follow-Me @ I SI Node Hardware Mica2Dot + “Button Box” (Sponsored by I ntel) Infrastructureless Location Aware Introduction 5 Configuration for Sensor Networks
Follow-Me I n Context � Compared with signs or computer kiosks � Follow-me guides visitors as they move through a building (active assistance) � Applications � Demonstrate basic technologies in office environments � Other applications about sensor node assisted navigation can be derived, including: � Emergency evacuation � Underground exploration Infrastructureless Location Aware Introduction 6 Configuration for Sensor Networks
Logical Location & Logical Topology Map of I SI 11 th Floor � Logical Location (physical topology) � The relationship of nodes with each other and their 06 08 09 17 22 01 02 03 04 05 11 12 15 16 20 23 76 63 24 07 10 13 14 18 19 21 25 75 62 environment 61 26 68 74 85 60 59 65 80 67 79 64 66 77 78 81 82 83 84 58 27 69 � E.g. at room 1234, at the 57 56 70 55 28 71 intersection of x and y 72 29 54 45 35 32 49 42 4140 38 34 33 73 30 53 52 50 48 47 46 44 43 31 51 39 37 36 � Logical Topology consists of Logical Locations � Logical Topology in this work � Connects nodes as a human would walk, as opposed to the radio or physical topologies, or we can call it “walkable connectivity” Logical Topology Infrastructureless Location Aware Introduction 7 Configuration for Sensor Networks
Logical Location & Follow Me Map of I SI 11 th Floor � Specific definition of logical (physical topology) location in this work � In logical topology, which sensor 06 08 09 17 22 01 02 03 04 05 11 12 15 16 20 23 76 63 24 07 10 13 14 18 19 21 25 75 nodes are adjacent to which 62 61 26 68 74 85 60 59 65 80 67 79 64 66 77 78 81 82 83 84 other sensor nodes 58 27 69 57 56 70 � Expressed as a set of neighbors 55 28 71 72 29 54 for each node 45 35 32 49 42 4140 38 34 33 73 30 53 52 50 48 47 46 44 43 31 51 39 37 36 � Deriving logical location information for path finding is the main technical challenge of follow-me � We developed the deployment order method for logical location configuration Logical Topology Infrastructureless Location Aware Introduction 8 Configuration for Sensor Networks
Logical Location vs. Routing Map of I SI 11 th Floor (physical topology) � Network connectivity cannot directly infer 06 08 09 17 22 01 02 03 04 05 11 12 15 16 20 23 76 63 24 07 10 13 14 18 19 21 25 75 62 logical location 61 26 68 74 85 60 59 65 80 67 79 64 66 77 78 81 82 83 84 58 27 69 57 56 70 � Unlike radio waves, humans 55 28 71 72 29 54 45 35 32 49 42 4140 38 34 33 73 30 53 52 are constrained by physical 50 48 47 46 44 43 31 51 39 37 36 walls Radio Connectivity Logical Topology Infrastructureless Location Aware Introduction 9 Configuration for Sensor Networks
I ntroduction Deployment Order I mplementation and Extensions Future Work and Conclusion
Deployment Order – The I dea � Sensor nodes are often deployed (switched on) sequentially � E.g. Dropped one by one by a person or vehicle � Deployment order takes advantage of this information to infer logical topology � An “easy” description � When two nodes are deployed (switched on) one after the other within a short time, we assume that they are neighbors in logical topology Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 11
Deployment Order Overview I f nodes are deployed in this order 1 2 3 4 Deployment order will infer this logical topology automatically � The basic mechanism � A newly deployed node communicates with existing nodes to find out deployment order information � “Intersections” (non-linear topologies) are handled by interactive configuration Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 12
Deployment Order Defined � Deployment order is defined with a simple state machine Timeout (2 sec) Timeout (1 min) Active Passive Receptive (Power On) (Normal) Replied Connection Request � Three states � Active: Looking for existing nodes � The state after a node is switched on � Send out connection request packets � Receptive: Want to link to a new node � Will reply to connection request packets and create a link � Passive: Done � Will not be involved in link operations – state for normal operation Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 13
Linear Topology Example – First Node (a) (b) (c) (d) (e) Active (f) Receptive (g) Passive (h) 1 2 3 4 (a) The first node is switched on (b) It won't find any neighbor and will go to receptive state Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 14
Linear Topology Example – First Link (a) (b) (c) (d) (e) Active (f) Receptive (g) Passive (h) 1 2 3 4 (c) When the second node is switched on it begins in active state and will search for neighbors The first node (currently receptive) will reply, establishing a link between these two nodes Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 15
Linear Topology Example – Ready For Another Node (a) (b) (c) (d) (e) Active (f) Receptive (g) Passive (h) 1 2 3 4 (d) The first node will move to passive state after creating the link, and the second will go to receptive state Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 16
Linear Topology Example – More Nodes (a) (b) (c) (d) (e) Active (f) Receptive (g) Passive (h) 1 2 3 4 (e) – (h) Similarly, the third node will link to the second node, and so on Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 17
I ntersections and Arbitrary Topologies � Intersections mean nodes with more than 2 neighbors � Approach � If we give users a little bit of control over the state machine, they can then connect nodes to make arbitrary topologies � We use a button on sensor node to toggle node states Infrastructureless Location Aware Deployment Order Configuration for Sensor Networks 18
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