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Motivation

EmberNet – Wireless Networks for Industrial Systems Presented by Ryan Wu April 11, 2003 Some slides and figures courtesy EmberNet, Rob Poor and Cliff Bowman. Motivation. Traditional Wireless Systems for Industry Point-to-Point Point-to-Multipoint Pros v.s. Cons

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Motivation

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  1. EmberNet – Wireless Networks for Industrial Systems Presented by Ryan WuApril 11, 2003Some slides and figures courtesy EmberNet, Rob Poor and Cliff Bowman

  2. Motivation • Traditional Wireless Systems for Industry • Point-to-Point • Point-to-Multipoint • Pros v.s. Cons • Structure, planning, signal failures… • New approach: • Wireless Mesh Network

  3. To meet the need • The network does not require sophisticated planning and site mapping to achieve reliable communication • Self-configuring, no human assistance needed • Devices are able to transmit without moving • Low error rate • Low cost (energy and $ )

  4. Wireless Mesh Network • Mesh Network: • At least two nodes with two or more paths between them (Redundancy) • E.g. Internet backbone • Pros: • Reliability; • Adaptability; • Scalability • Cons:? • Mesh Network v.s. Peer-to-Peer?

  5. Outline • Communication Architecture • Ember Technology (Nodes and Gateway) • Gradient Routing and Service Discovery

  6. Communication-Mesh Network • IEEE 802.15.4 (WPAN) • Low rate (250,40,20 kbps at 2.4G/868/915MHz) • Low power (goal: 3 AA for years) • Antennas: 1000 feet in open air, 20dBM • No clear support for network diagnosis • Loss retransmission at higher layer…

  7. Ember Networks • EmberNet nodes • embedded wireless networking peripheral • 900MHz/2.4GHz • 3.81 x 5.59 x .76 cm • EmberNet gateways • 192 MHz,32 MB SDRAM, • Intrinsyc Linux 4.1 Distribution

  8. EmberNet Nodes • EmberNet SPI: Synchronous serial hardware interface • Host API provides a simple, consistent interface to the routing, discovery, and service management in the EmberNet Protocol Stack on the EmberNet Node

  9. EmberNet Gateway • 10 Base-T Ethernet port • 16MB Flash, 32 MB SDRAM, diskless • Intrinsyc Linux 4.1 Distribution • EmberNet Protocol Stack, EmberNet View, Apache HTTP Server

  10. Design and Programming • Distributed task and messaging • Match to available resources (compute, space, etc. ) • Exception-based (event driven) msg • Reliability? (when multi-hops…)

  11. Ad Hoc Routing • Things to consider: • Energy • Scalability • And ? • Traditional routing protocols • Distance vector approach • Link state approach

  12. Gradient Ad Hoc Routing • Each node is also a router • ”Cost” as a measurement, advertising to others • Only the neighboring ones that can delivery at a lower cost will relay the msg

  13. More details of GRAd

  14. And more … • A service point of view • Services are destinations for messages • Service descriptions not unique: (need nodeID) • Change nodeID to represent devices added/lost replaced • Discovery: send msg with discovery flag • Processors could filter messages and drop the not matched ones…

  15. And more: Discussion • Pros of GRAd • Conceptually simple • Loop free (gradient like) • Limited data to keep at each node • And? • Cons of Grad • Scalability ? • Problems with broadcast ? • Interference and Collision ? • Others ?

  16. Discussions • Compared with ”smart dust” ? • Compared with ”TinyOS” ? • Other Comments ?

  17. Reference • White Paper of EmberNet • Gradient Routing in Ad Hoc Networks • IEEE 802.15.4 http://www.ieee802.org/15/pub/TG4.html • www.ember.com

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