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 Structure, planning, signal failures… New approach: Wireless Mesh Network

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 $ )

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? Wireless Mesh Network

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

Communication-Mesh Network IEEE (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…

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

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

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

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

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

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

More details of GRAd

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…

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 ?

Discussions Compared with ”smart dust” ? Compared with ”TinyOS” ? Other Comments ?

Reference White Paper of EmberNet Gradient Routing in Ad Hoc Networks IEEE