Software Radio, GNU Radio, and the USRP Product FamilyOpen Hardware for Software Radio

Matt Ettus, matt@ettus.com

Software Radio

Simple, general-purpose hardware

Do as much as possible in software− Everyone's definition is different

Continuum

Everything Box vs. New Directions

Dynamic Spectrum Management

Cognitive Radio

GNU Radio

A tool for rapid prototyping AND deployment of software radios

Free Software A platform for signal processing on

commodity hardware A platform for digital communications

research

GNU Radio Features Seamless Multithreading Easy to program, object-oriented interface Designs written in C++ or Python, a high-level language Extremely Fast

− DSP Primitives in C++ and often hand-coded SIMD Assembly

Built in standard signal-processing constructs GUI Integration Filter design Hides all memory, buffering, scheduling concerns Free software (GPL)

GNU Radio “Hello World”

GNU Radio Companion (GRC)

Achievements

Large, diverse user community (>1000) Transmit and Receive many waveforms

− AM, FM, FM Stereo, TV, etc− GMSK, PSK, OFDM, spread spectrum, etc.− ATSC (HDTV) Transmitter and Receiver

Highly Portable – same user code runs on− Linux, Mac OS X, Windows, NetBSD

− X86 (32/64), PPC (32/64), Cell, ARM, OMAP

Universal Software Radio Peripheral (USRP)

Very Low Cost Open design / IP Interchangeable RF sections Wide bandwidth Extreme flexibility Beamforming/MIMO/Smart Antenna capable Large community Co-developed with GNU Radio

USRP

USRP Features

Quad 64 MS/s 12-bit ADCs Quad 128 MS/s 14-bit DACs USB 2.0 Interface

− Handles 8 MHz of instantaneous, continuously streaming RF Bandwidth at 16 bits per sample

Low speed analog I/O for RSSI/gain control FPGA for high speed DSP ops 2-Way MIMO “out of the box”

− 4-Way if using external RF frontends

Daughterboards

BasicTX and BasicRX− For use with external RF sections− Flexible IF (0 to 200 MHz)

LFRX and LFTX− DC to 30 MHz

TVRX− 50-860 MHz receiver

DBSRX− 800 MHz – 2.4 GHz receiver

Transceiver Daughterboards

RFX400 – 400-500 MHz transceiver, 100+mW output RFX900 -- 800-1000 MHz Transceiver, 250+ mW output

− Ham + ISM bands, modifiable for 1600-2000MHz RFX1200 -- 1150-1400 Mhz, 200+ mW output

− Ham, Satellite, Navigation bands RFX1800 -- 1500-2100 MHz, 250+ mW output

− PCS, Cell, DECT RFX2400 -- 50+ mW output, 2300-2800 Mhz

− Ham, ISM bands XVCR2450 – 50-250 mW output, 2.4-2.5GHz

and 4.8 to 5.9 GHz

New Transceiver Daughterboards (coming in '09)

50 MHz to 1 GHz Transceiver 800 MHz to 2.2 GHz Transceiver Both are MIMO Capable, 100+ mW output

USRP applications

Multi-Mbps GMSK, PSK, OFDM, MIMO networking MAC-layer development ZigBee, DECT, GSM, 802.11b Spectrum occupancy studies Cognitive Radio Active and Passive Radar SIGINT/COMINT Ham radio GPS (incl. multi-antenna receivers)

− http://www.gps-sdr.com RFID Mobile phone location and tracking Mobile phone base stations

− http://openbts.sf.net

USRP Applications, cont'd

Dynamic Spectrum Access Over the horizon ship-tracking radar (port security) Public safety

− Linking multiple diverse radio systems− In-building reliable firefighter communications

Soldier in the field smart radios Wildlife tracking Medical imaging Teaching and student research Radio astronomy Security Research Satellite Ground Stations Project hosting at https://www.cgran.org/wiki/

Status

Large, diverse user community− About 3500 in use in 61 countries− Academic, Commercial, Military− Ham, Hobbyist, Radio Astronomy, SETI, etc.

Many non-GNU Radio users− SCA

OSSIE from Virginia Tech SCARI from CRC

− Matlab/Simulink− LabView

Several Full-time GNU Radio/USRP consultants

− Custom hardware, FPGA, and software design

USRP2 Features

100 MS/s 14-bit dual (IQ) ADCs− ~80 MHz instantaneous RF bandwidth

400 MS/s 16-bit dual (IQ) DACs Gigabit Ethernet interface

− 3-6x improvement over USB− Allows for 25 MHz of RF BW each way @16bits

Wide enough for WiFi!

USRP2 Features, cont'd

Bigger FPGA w/Multipliers (Spartan 3) 1 MB high-speed on-board SRAM High speed serial expansion interface Configured by flash

− Can operate without host computer

USRP2 Features, cont'd

External Frequency Reference Input − Flexible choice of reference, not just 10 MHz

Pulse per second (PPS) input for precise timing

Uses the same daughterboards as USRP1− Only holds 1 TX and 1 RX− MIMO via expansion interface

Shipped in September 2008

USRP2 Layout

USRP2 PCB

USRP2

USRP2 FPGA

Spartan 3− ~40K logic cells, Lots of RAM and multipliers

32-bit RISC Processor soft core− 50 MHz− GCC toolchain

FIFOs and full crossbar between interfaces− Aggregate 3.2 GBytes per second internal BW− Very low latency− Saturate GigE in both directions at once

Precise timing control (10ns) for TDMA, etc.

USRP2 FPGA, cont'd

Extensive use of Opencores.org− Processor− Wishbone Bus− Interrupt controller, GPIO, SPI, I2C, UART− Gigabit Ethernet MAC− CPLD Flash bootstrap

WISHBONE Bus

Buffer Pool and Stream Interfaces

High-Speed Serial Link

Four differential signals in each direction− Carries data at 2 Gbps each way− Reference clock for phase locking oscillators− Time sync signal− One high speed differential link available for user

Network of USRP2 “Line Cards”− Two USRP2s linked directly− Four or more USRP2s linked by hub

High-Speed Serial Link, cont'd

MIMO Applications− Each USRP2 handles 1 antenna− Everything is fully coherent to 1 master oscillator

Low-cost industry-standard cabling− Serial-attached SCSI (SAS)

Rack Mount (3U) Option

Resources

Ettus Research LLC− http://ettus.com− matt@ettus.com

GNU Radio Home Page− Wiki, Source Code, Schematics, Mailing Lists− http://gnuradio.org/trac

External Project Hosting (CGRAN)− https://www.cgran.org/wiki/