Transcript Community Wireless Networks

A Geography-Aware Community
Wireless Testbed
RPI, Troy, NY
Bow-Nan Cheng, Max Klein
Shivkumar Kalyanaraman
Email: [email protected]
Rensselaer Polytechnic Institute
Funding: NSF-ITR 0313095, Intel
: “shiv rpi” Shivkumar Kalyanaraman
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Outline
Wireless Ad-hoc Mesh Networks: Challenges
 Physical Layer: A “street-level” network
 Network Layer: Addressing Framework and Autoconfiguration
 Microcosm Test Bed Lab
 Future Work

Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Community Wireless: What’s New?
Lots of work in ad-hoc networks coming to fruition
 Startup companies in the mesh networks space:
 Tropic networks, Mesh networks etc

What’s different in CWNs? Why a testbed?
 Unmanaged, but operational network
 Ad-hoc, but operational
 Fixed (I.e. not mobile)
 Medium scale
 Supports organic growth and evolution
 Supports legacy internet traffic
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute

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Community Wireless Networks:
Challenges ? Why a Testbed?

Auto-configuration and auto-management:
Only lightweight “governance” allowed
 Beyond addressing: routing, naming, other protocols

Higher quality than ad-hoc networks to support
legacy applications (links, end-to-end transport)
 Capacity maximization (c.f. Gupta/Kumar results)
=> routing choices, traffic engineering
 Cheap, simple, standards-based components.
 New community apps (eg: p2p video, games).

Several nitty-gritty issues leading to new protocol
design challenges… best researched inShivkumar
a testbed…
Kalyanaraman
Rensselaer Polytechnic Institute

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Broadband exists. Why CWN?

Ans: Multiplicity.
 Cable modem and DSL and CWN and …
 Commodity => cheap to get multiple access facilities …
Phone modem
USB/802.11a/b
802.11a
WiFi (802.11b)
Ethernet
Firewire/802.11a/b
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Physical Layer: Street-level vs Rooftop
Leverage directionality and quasi-LOS
of streets => better quality links
 Omni-directional vs.
Directional Antennas

Eg:
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Antennas: Pringles cans disappoint


Cheap…
But low gain:
6.01425 dBi
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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COTS Directional Antennas
2.4 GHz 12 dBi Radome Enclosed Yagi
Superior performance
Light weight
All weather operation
45° beam-width
Can be installed for either vertical or horizontal
Polarization. Includes tilt and swivel mast mount
Rensselaer Polytechnic Institute
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Shivkumar Kalyanaraman
Network Layer: Addressing

Goals:
 IP-based architecture
 Support for geographic routing
 Why?
Medium-scale, Organic Growth, Locationservices
 Support
 Why?
 Support

for local traffic engineering
Dirn antennas, capacity maximization.
for distributed auto-configuration
Proposed Addressing Framework:
 Geographic Distributed Addressing (GDA)
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Geographic
Distributed
Addressing (GDA)
Idea: Hash GPS -> IP address
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Why GPS-to-IP?


GPS-to-IP =>

Medium-scale, Server-less auto-configuration,

With routable addresses…
IP address has dual semantics: geographic and topological




Long-range geographic routing/TE
Short-range: (k-hop) topological RF-aware QoS routing
… using the same IP/geographic address…
Location information also leveraged to auto-configure other
L2/L3 protocols:

Eg: cluster/area boundaries for routing, support location-based CWN
services
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Future: Geographic Source Routing
TBR route
Trajectory defined as a
parametric curve
A
Shortest-Path
route
Q(t)
B
Gives us ability
to pick randomly
from a large
number of
physical routes
Greedy
Routing
Source
Routing
i.e. no header
or state, but
no flex
i.e. flex,
large header
Trajectory-Based Routing
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Deployment Plan
Microcosm lab: internal prototyping, tests
 Logistics for long-term deployment around RPI
campus (eg: dealing with landlords etc)
 RPI-CIO providing access points at borders of campus
to help connect the CWN to RPI’s internal network

Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Microcosm Test Lab
Variable attenuators, and directional antennas allow flexibility
in testing
We also intend to use public facilities like Utah’s Emulab Wireless
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Testbed Hardware… contd
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Testbed: Software
Fixed Nodes:
- RedHat Linux Kernel 2.4.20-30.9
- Click Modular Router: CVS March 5
Autoconfigured Nodes:
- Redhat Linux 9: 2.4.20/21 Kernel
- Click Modular Router: CVS March 5
- HostAP 0.2 Driver + Utilities for
Firmware flashing
- GPSD 1.10
- DHCP Server + preconfigured NAT
w/ iptables ipmasq
- Customized GSP Autoconf Scripts
- Webserver + SSH in the future
-Intel Stargate/east platform will be considered as well
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Future Work

GeoNet Framework to verify intersection between Geography
and Topological routing
 K-hop RF Awareness, QoS routing
 Distributed Geographic Traffic Engineering

Test Bed Improvements
 GPS Simulation
 Lab Reflectivity

Transport and application-layer activities kicked off
 Key: survival & quality under heavy erasure conditions.
 Collaboration ongoing with Intel and AT&T Research
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Vision #1: Multipath P2P Video/Data Over CWNs
“Slow” path
“Fast” path
P
Traffic engineering &
Transport level upgrades
I
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Vision #2: free-space-optical CWN
Ongoing NSF-STI project…
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Thanks!
Student Heroes:
Bow-Nan Cheng: [email protected]
Max Klein: [email protected]
: “shiv rpi”
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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