Post on 18-Jan-2018
description
EmberNet – Wireless Networks for Industrial Systems
Presented by Ryan WuApril 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 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…
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 802.15.4 http://www.ieee802.org/15/pub/TG4.html www.ember.com