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Wireless Networking Research Hydra Demonstration Hydra An Open Source Wireless Testbed Hyrum K. Wright, Robert D. Grant Wireless Communication and Networking Group Department of Electrical and Computer Engineering The University of Texas at

SLIDE 1

Wireless Networking Research Hydra Demonstration

Hydra

An Open Source Wireless Testbed Hyrum K. Wright, Robert D. Grant

Wireless Communication and Networking Group Department of Electrical and Computer Engineering The University of Texas at Austin

July 23, 2008

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 2

Wireless Networking Research Hydra Demonstration

1 Wireless Networking Research

What Why How

2 Hydra

Implementation Options High-level Overview Nitty-gritty details

3 Demonstration

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 3

Wireless Networking Research Hydra Demonstration What Why How

Wired network != Wireless network

Traditional wired-network assumptions break down in the wireless world. The medium is half-duplex broadcast, not full-duplex point-to-point Channels vary in time and frequency domains Mobility results in rapidly changing link states

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 4

Wireless Networking Research Hydra Demonstration What Why How

What we study

Wireless communication at the PHY, MAC, and routing layers. Particularly, Cross-layer algorithms (e.g., rate adaptation) MIMO (multi-antenna systems) Multi-hop networks

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 5

Wireless Networking Research Hydra Demonstration What Why How

Why we study this stuff

Practical research for the next generation of wireless networking. Ad hoc networking can extend network range, help networks scale, and connect places previously unconnected by traditional networks MIMO and cross-layer algorithms can help improve network performance

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 6

Wireless Networking Research Hydra Demonstration What Why How

How we study wireless networks

Tools

Theory Simulation Emulation Implementation

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 7

Wireless Networking Research Hydra Demonstration What Why How

How we study wireless networks

Tools

Theory Simulation Emulation Implementation Flexible Abstract Difficult Constraining

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 8

Wireless Networking Research Hydra Demonstration What Why How

Current Open Source Tools

Theory - GNU Octave, R Simulation - NS2, OMNeT++ Emulation - Emulab, NS Emulator Implementation - GNU Radio, IT++, Click

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 9

Wireless Networking Research Hydra Demonstration What Why How

Weaknesses of Current Open Source Tools

NS2, OMNeT++ - Difficult to get details of wireless right in simulation Emulab, NS Emulator - Built for wired networks, though people are trying to extend them to wireless GNU Radio, IT++ - Good tools, but low level. GNU Radio was built for stream processing, not packet processing.

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 10

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Hydra

Goal Develop a flexible platform for wireless research and experimentation which uses real channels.

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 11

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Implementation Options

Application Specific Integrated Circuit (ASIC)

Great performance High cost Difficult to change, revise

FPGA

Easier than ASIC to modify Commodity part = easy to obtain Still requires hardware knowledge to develop

Software Defined Radio (SDR) Platform

Acceptable (but worse) performance Highly customizable Does not require hardware knowledge to program

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 12

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Hydra

An open-source, flexible testbed for wireless experimentation, almost entirely in software.

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 13

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Hydra Node

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 14

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

High Level

Each node is a general purpose x86 machine Upper layers are GNU/Linux Link layer and MAC layer are implemented in Click Modular Router PHY layer is implemented in C++ and wrapped in GNU Radio Hardware is one or more Universal Software Radio Peripheral (USRP) boards, attached via USB

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 15

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Hydra Block Diagram

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 16

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

All Open Source Components

The USRP - all FPGA code and designs are open! GNU/Linux operating system GNU Radio Software Radio Framework Click Modular Router IT++ (and its dependencies) C++, Python, and SWIG GNU Octave (in the works!)

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 17

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

The Upper Layers

Hydra runs standard applications (ping, Firefox, Apache, FTP). Works through the Linux TUN device A virtual network device (/dev/net/tun) Allows Click to send IP packets from userspace to the Linux kernel’s IP processing code Allows the kernel to pass IP packets to Click in userspace

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 18

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Link Layer

Media Access Control: Distributed algorithms for determining transmission priority. i.e., “Who gets to talk when” Click Modular Router A modular packet router which integrates with Linux. Can run in either user or kernel mode. Creates an additional network interface which applications can use seamlessly. Current MAC implementations: 802.11, plus experimental protocols such as RBAR, OAR and others. Using C++, we define “blocks,” and then connect those blocks in a flow graph.

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 19

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Link Layer

Figure: Click DSDV implementation

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 20

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Physical Layer

802.11a and 802.11n style physical layers implemented Implemented in C++ using the IT++ communications library Entire physical layer wrapped in a single GNU Radio Block Visualizations written using Matplotlib, wxpython

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 21

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Physical Layer

Frame Synch Packet Detector Remove Freq Offset Decode Header CRC OK?

yes no Decode Payload Return to Packet Detector Baseband Input

Payload + Training

Phase Tracking Channel Estimation Spatial Equalization FFT Phase Tracking Soft Bits Mapping Soft Bits Mapping Deinter- leaving Deinter- leaving Soft Bits Deparsing

Binary Output

Bit Scrambling Viterbi Decoder FFT Delete CP + Training

Processed OFDM Symbol by OFDM Symbol

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 22

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Side Project: Octave Integration

Our current physical layer is written in C++ Most physical layer researchers are used to MATLAB Solution: GNU Octave, an open source version of MATLAB

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 23

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Octave Integration Structure

Client/Server architecture TCP server interface to USRP TCP client in GNU Octave Physical layer in GNU Octave

Functional structure. A series of transformations on data to transmit or receive. Runs in Octave and MATLAB Custom unit-testing framework

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 24

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Research

Mostly in cross-layer MAC/PHY algorithms Physical layer rate control MAC frame aggregation MIMO

Beamforming Limited feedback

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 25

Wireless Networking Research Hydra Demonstration Implementation Options High-level Overview Nitty-gritty details

Future

More experiments – Hydra is starting to stabilize as an experimental platform More nodes – scale up our test network Make easier to use. . .

Release code – backend cleanup! Expand Octave integration Use in the classroom

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 26

Wireless Networking Research Hydra Demonstration

Demo Time

BAM

Hyrum K. Wright, Robert D. Grant Hydra

SLIDE 27

Wireless Networking Research Hydra Demonstration

Questions?

Resources Hydra: http://hydra.ece.utexas.edu/ GNU Radio: http://www.gnu.org/software/gnuradio/ Obligatory Sponsor Info National Science Foundation, under grant CNS-626797 Office of Naval Research (ONR), under grant number N00014-05-1-0169 DARPA IT-MANET program, under grant W911NF-07-1-0028

Hyrum K. Wright, Robert D. Grant Hydra

Hydra

An Open Source Wireless Testbed Hyrum K. Wright, Robert D. Grant

Wireless Communication and Networking Group Department of Electrical and Computer Engineering The University of Texas at Austin

July 23, 2008

1 Wireless Networking Research

What Why How

2 Hydra

Implementation Options High-level Overview Nitty-gritty details

3 Demonstration

Wired network != Wireless network

Traditional wired-network assumptions break down in the wireless world. The medium is half-duplex broadcast, not full-duplex point-to-point Channels vary in time and frequency domains Mobility results in rapidly changing link states

What we study

Wireless communication at the PHY, MAC, and routing layers. Particularly, Cross-layer algorithms (e.g., rate adaptation) MIMO (multi-antenna systems) Multi-hop networks

Why we study this stuff

Practical research for the next generation of wireless networking. Ad hoc networking can extend network range, help networks scale, and connect places previously unconnected by traditional networks MIMO and cross-layer algorithms can help improve network performance

How we study wireless networks

Tools

Theory Simulation Emulation Implementation

How we study wireless networks

Tools

Theory Simulation Emulation Implementation Flexible Abstract Difficult Constraining

Current Open Source Tools

Theory - GNU Octave, R Simulation - NS2, OMNeT++ Emulation - Emulab, NS Emulator Implementation - GNU Radio, IT++, Click

Weaknesses of Current Open Source Tools

NS2, OMNeT++ - Difficult to get details of wireless right in simulation Emulab, NS Emulator - Built for wired networks, though people are trying to extend them to wireless GNU Radio, IT++ - Good tools, but low level. GNU Radio was built for stream processing, not packet processing.

Hydra

Goal Develop a flexible platform for wireless research and experimentation which uses real channels.

Implementation Options

Application Specific Integrated Circuit (ASIC)

Great performance High cost Difficult to change, revise

FPGA

Easier than ASIC to modify Commodity part = easy to obtain Still requires hardware knowledge to develop

Software Defined Radio (SDR) Platform

Acceptable (but worse) performance Highly customizable Does not require hardware knowledge to program

Hydra

An open-source, flexible testbed for wireless experimentation, almost entirely in software.

Hydra Node

High Level

Each node is a general purpose x86 machine Upper layers are GNU/Linux Link layer and MAC layer are implemented in Click Modular Router PHY layer is implemented in C++ and wrapped in GNU Radio Hardware is one or more Universal Software Radio Peripheral (USRP) boards, attached via USB

Hydra Block Diagram

All Open Source Components

The USRP - all FPGA code and designs are open! GNU/Linux operating system GNU Radio Software Radio Framework Click Modular Router IT++ (and its dependencies) C++, Python, and SWIG GNU Octave (in the works!)

The Upper Layers

Hydra runs standard applications (ping, Firefox, Apache, FTP). Works through the Linux TUN device A virtual network device (/dev/net/tun) Allows Click to send IP packets from userspace to the Linux kernel’s IP processing code Allows the kernel to pass IP packets to Click in userspace

Link Layer

Link Layer

Figure: Click DSDV implementation

Physical Layer

802.11a and 802.11n style physical layers implemented Implemented in C++ using the IT++ communications library Entire physical layer wrapped in a single GNU Radio Block Visualizations written using Matplotlib, wxpython

Physical Layer

Side Project: Octave Integration

Our current physical layer is written in C++ Most physical layer researchers are used to MATLAB Solution: GNU Octave, an open source version of MATLAB

Octave Integration Structure

Client/Server architecture TCP server interface to USRP TCP client in GNU Octave Physical layer in GNU Octave

Functional structure. A series of transformations on data to transmit or receive. Runs in Octave and MATLAB Custom unit-testing framework

Research

Mostly in cross-layer MAC/PHY algorithms Physical layer rate control MAC frame aggregation MIMO

Beamforming Limited feedback

Future

More experiments – Hydra is starting to stabilize as an experimental platform More nodes – scale up our test network Make easier to use. . .

More documentation More visualization More experimental tools Easier network administration

Release code – backend cleanup! Expand Octave integration Use in the classroom

Demo Time

BAM

Questions?

Resources Hydra: http://hydra.ece.utexas.edu/ GNU Radio: http://www.gnu.org/software/gnuradio/ Obligatory Sponsor Info National Science Foundation, under grant CNS-626797 Office of Naval Research (ONR), under grant number N00014-05-1-0169 DARPA IT-MANET program, under grant W911NF-07-1-0028