The Case of User Cooperation

Developing Next-Generation Wireless using WARP:
The Case of User Cooperation
Chris Hunter, Ashutosh Sabharwal
Patrick Murphy
{chunter,ashu}@rice.edu
Rice University
patrick@mangocomm.com
Mango Communications
Outline
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WARP Overview
Research Examples
Case Study: User Cooperation
Demonstration
Wireless Open-Access
Research Platform
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Cross-layer design
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Completely programmable,
from PHY through
networking
Fast timescales and wide
bandwidths
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40MHz bandwidth per radio
Turn-around-Times in
~20µsec
Wireless Open-Access
Research Platform
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WARP refers to two things
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The Hardware
The Support Packages
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Xilinx Virtex-4 FX100 FPGA
(XC4VFX100-11FFG1517C)
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All processing is local to the board (no host PC required)
FPGA fabric to handle PHY processing
PPC (inside FPGA) to handle MAC processing
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Up to 4 radio interfaces
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MAX2829-based RF front-end (2.4/5GHz, 40MHz BW)
All frequency locked for MIMO applications
Slots can be used for other daughterboards
Platform Support Packages
Inter-FPGA Board
Links
MGTs
Hardware
Description
Logic
Logic-Bus
Interface
PPCs
Xilinx FPGA
FPGA Board
Peripheral
Interfaces
Radio
Video
Analog I/O
Daughtercards
WARP Hardware
warp.rice.edu
WARP Repository
Research Applications
WARPLab
rapid PHY prototyping
WARPLab
Ethernet links
WARPLab
• One PC controls many
WARP nodes
• MATLAB for signal
processing
• Non-real-time
processing
• WARP for wireless interfaces
• Real-time channel use
WARP real-time
host-free processing
OFDM Reference Design
MAC Research Application
PPC Code
WARPMAC
WARPPHY
PHY
Driver
DMA
Driver
Timer
Driver
Misc.
Drivers
Ethernet
MAC Driver
Custom
PHY
Packet
Buffers
Timer
Radio
Controller
Ethernet
MAC
PLB
MIMO OFDM MIMO OFDM
Transmitter
Receiver
Digital
I/Q
AGC
Digital
I/Q
I/Q &
RSSI
Radio
Bridges
Radios
FPGA Logic
Packet
Detector
RSSI
Control
Ethernet
Hardware
WARPnet
enables experiments with networks
Channel
Controlled: Node position, Tx Power, etc.
Uncontrolled: Multipath fading, interference, etc.
Was observed effect due to my
controlledChannel
parameters or due
to causes beyond my control?
Controlled: Node position, Tx Power, etc.
Uncontrolled: Multipath fading, interference, etc.
Channel
Observations
Control
Real-time Network Monitoring with WARPnet
WARPLab
WARP real-time
WARPnet
Examples: Directional Mobility
Examples: Directional Mobility
Examples: Directional Mobility
,*-.%)/$."#'&*'#$)##'0
3.2 cm
3.2 cm
1*"+#.2-.%)/$."#'&* '#$)##'
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7'8$"8
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3-5 dB link gain, higher with more antenna patches
(Amiri, Zhong @ Mobicom 2010)
Examples: Directional Mobility
Video of Real-Time Directional Mobility Testbed
Examples: Full Duplex
Examples: Full Duplex
•  2 WARP nodes, each with
3 Radios (2 Tx + 1 Rx)!
•  10 MHz OFDM!
•  Inter-node distance 10m.!
•  80dB self-interference
suppression!
•  50-70% throughput gain!
•  Duarte & Sabharwal, 2010!
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Examples: User Cooperation
Broadcast Phase
Relay Phase
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Examples: User Cooperation
Initial Transmission
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Header
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Payload
Header
Payload
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Examples: User Cooperation
Initial Transmission
NACK Transmission
Header
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Header
Payload
Header
Payload
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Header
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Examples: User Cooperation
NACK Transmission
Coop. Retransmission
Header
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Header
Payload
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Header
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only cooperates when retransmission
On-demand:
would happen anyway
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Examples:
Cooperation
X Location (m)
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X Location (m)
Y Location
Y Location
(m)
(m)
Y-Location
(m)
Y Location (m)
! !Throughput
(Mbps)
Throughput
(Mbps)
Throughput
Improvement
over
CSMA/CA
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(Mbps)
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X XLocation
Location(m)
(m)
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Relay
Transmission
Rate
Relay
Transmission
Rate
a) In0 DOC, the relay
provides
maximal
amount of assistance 0when
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ocated between the source and the destination.
X Location (m)
warp.rice.edu/papers
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WARP hardware provides resources for next-generation wireless
WARP platform support provides high-level access to resources
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WARPLab for PHY prototyping
Real-time implementation for real-world timescales
WARPnet for network testing
warp.rice.edu