mimo development efforts at virginia tech · mimo development efforts at virginia tech s. ellingson...

Slide Slide 11http://http://www.ece.vt.edu/~swe/mcmswww.ece.vt.edu/~swe/mcms//

Ellingson, Ellingson, MostafaMostafa, & Reed , & Reed –– Sept 19, 2004Sept 19, 2004

MIMO Development EffortsMIMO Development Effortsat Virginia Techat Virginia Tech

S. Ellingson S. Ellingson 11, R. , R. MostafaMostafa 22 & J. Reed & J. Reed 22

{{ellingson,ramostaf,jhreed}@vt.eduellingson,ramostaf,jhreed}@vt.edu

1 1 Virginia Tech Antenna Group (VTAG)Virginia Tech Antenna Group (VTAG)22 Mobile & Portable Radio Research Group (MPRG)Mobile & Portable Radio Research Group (MPRG)

Bradley Dept. of Electrical & Computer EngineeringBradley Dept. of Electrical & Computer EngineeringVirginia Polytechnic Institute & State UniversityVirginia Polytechnic Institute & State University340 340 WhittemoreWhittemore Hall, Blacksburg VA 24061Hall, Blacksburg VA 24061

September 19, 2004September 19, 2004



MIMO at Virginia TechMIMO at Virginia Tech

Virginia Tech is interested in all aspects of MIMO:Virginia Tech is interested in all aspects of MIMO:MIMO channel physicsMIMO channel physicsMIMO communication theory MIMO communication theory Practical implementation Practical implementation (HW, SW, Systems, & Networks)(HW, SW, Systems, & Networks)

This talk:This talk:Evolution of a serialEvolution of a serial--bus based data aggregation bus based data aggregation scheme for array receivers scheme for array receivers “Full” presentation (including more details on other “Full” presentation (including more details on other efforts) available:efforts) available:

http://www.ece.vt.edu/~swe/mcms/http://www.ece.vt.edu/~swe/mcms/http://http://www.mprg.orgwww.mprg.org//



Array Receiver ArchitecturesArray Receiver Architectures

A MIMO A MIMO communications linkcommunications link or or channel channel measurement systemmeasurement system consists of consists of

An array transmitter An array transmitter An array receiverAn array receiver

Array transmitters are “easy”Array transmitters are “easy”

Array receivers are Array receivers are hardhardData Aggregation (interconnects)Data Aggregation (interconnects)Processing Throughput (logic density)Processing Throughput (logic density)



SHF Array Experimental (SAX)SHF Array Experimental (SAX)

SHF Rack(24xx ↓ 435 MHz)

UHF Rack(435 ↓ 7.5 MHz)

A/D Conditioning,Power, and Cal

Rear View of Rack

16-Channel Digital Receiver (PC with A/D cards)

Classical“Polled Bus”

Data Aggregation

MIMOChannel

MeasurementProject

(1999-2000)



SAX: OnSAX: On--thethe--Fly Data DisplayFly Data Display



SAX: Field SAX: Field EvalEval of MIMO Capacityof MIMO CapacityIdeal NT=8Ideal NT=2

Measured NT=8Measured NT=2Measured NT=1

(Behind Building)(LOS)



SAX: Lessons LearnedSAX: Lessons Learned

Limitations of Polled Bus ArchitectureLimitations of Polled Bus ArchitectureData AggregationData AggregationProcessing ThroughputProcessing Throughput

MIMO Field StudiesMIMO Field StudiesEasy to be overrun by complexity, yet:Easy to be overrun by complexity, yet:Traditional architectures are too slow Traditional architectures are too slow --> Time IS money> Time IS moneyNear real time monitoring is GOOD (less wasted effort when thingNear real time monitoring is GOOD (less wasted effort when things go wrong!)s go wrong!)

More info:More info:S.W. Ellingson, "Effects of Angle Spread in a Complex Outdoor EnS.W. Ellingson, "Effects of Angle Spread in a Complex Outdoor Environment At vironment At 2.4 GHz", 2.4 GHz", 2003 IEEE Antennas & Propagation Soc. Int'l Symposium2003 IEEE Antennas & Propagation Soc. Int'l Symposium, Columbus, , Columbus, OH, June 2003 (OH, June 2003 (33:264:264--7). 7). S.W. Ellingson, "Vector Channel Coherence in a Complex Outdoor ES.W. Ellingson, "Vector Channel Coherence in a Complex Outdoor Environment nvironment At 2.4 GHz", At 2.4 GHz", 2003 IEEE Antennas & Propagation Soc. Int'l Symposium2003 IEEE Antennas & Propagation Soc. Int'l Symposium, , Columbus, OH, June 2003 (Columbus, OH, June 2003 (44:208:208--11). 11).

People involved:People involved: S. Ellingson, I. Gupta (OSU), J. S. Ellingson, I. Gupta (OSU), J. HetrickHetrick (TRW), K. (TRW), K. AyotteAyotte (OSU), G. (OSU), G. WhippsWhipps (OSU)(OSU)



Argus Argus •• Astrophysical transient search Astrophysical transient search

instrumentinstrument

•• N = 36 element array, 24 N = 36 element array, 24 instrumentedinstrumented

•• 12001200--1700 MHz tuning 1700 MHz tuning

•• TTsyssys ~ 215 K per element~ 215 K per element

•• Digitizes 20 MSPS complex (14 MHz Digitizes 20 MSPS complex (14 MHz BW); processed to 78.125 BW); processed to 78.125 kSPSkSPScomplex & aggregated into a single complex & aggregated into a single 8080--Mb/s serial data streamMb/s serial data stream

•• Data stream broadcast using UDP/IP Data stream broadcast using UDP/IP over Ethernet to PC cluster for all over Ethernet to PC cluster for all subsequent processing subsequent processing

•• Pulse sensitivity ~ 24 Pulse sensitivity ~ 24 kJykJy at zenith in at zenith in 0.2 s0.2 s



Argus Narrowband ProcessorArgus Narrowband Processor

•• Solves the “corner Solves the “corner turning” problem using turning” problem using serial bus architecture serial bus architecture implemented using implemented using LVDSLVDS

•• Control goes out, Control goes out, timetime--ordered data and ordered data and status comes backstatus comes back

•• Same architecture Same architecture simplifies additional simplifies additional processing & processing & interfaces to other interfaces to other systemssystems



Argus: Lessons LearnedArgus: Lessons Learned

LVDS LVDS serial bus technology is an effective replacement bus technology is an effective replacement for polled bus architectures, for polled bus architectures, especially especially for largefor large--N, lowN, low--BW systemsBW systems

More info:More info:S.W. Ellingson and G.A. Hampson, "Argus: An L-Band Array for Detection of Astronomical Transients," 2003 IEEE Int'l Ant. and Prop. Sym., Columbus, OH, June 2003 (3:256-9).S.W. Ellingson and G.A. Hampson, "Detection and Localization of L-Band Satellites Using an Antenna Array", 2004 IEEE Antennas & Propagation Soc. Int'l Symposium, Monterey, CA, June 2004.Project web site: http://www.ece.vt.edu/~swe/argus

Key involved: S. Ellingson, G. Hampson (CSIRO), many others…



Matrix Channel Measurement System Matrix Channel Measurement System (MCMS)(MCMS)

TAS

MCT - 4Channels

RAS

MCR - 16Channels

4 16

Vector / MatrixChannel

Under Test

Cal

Control/StatusSignal Flow

Key

250 MHz - 6 GHz40 MHz BW

Arbitrary, coherent waveforms

Continuous capture & On-the-fly analysis

•• Portable (2Portable (2--man lift)man lift)•• Battery Powered; 1Battery Powered; 1--hr minimumhr minimum

Application & frequencyspecific

Application & frequencyspecific



MCMS: MCMS: DownconverterDownconverter / Digitizer/ Digitizer

12 bit A/D 104MHz clock

Dual RJ45 ConnectorFor 1.248 Gb/sLVDS output

IF input(78 MHz center)

Up/Down/Down + Down/Down Superhet250 MHz - 6 GHz tuning

40 MHz BW



MCMS: Digital IF BoardMCMS: Digital IF Board

DB37 BackplaneConnector•3.3V, 1.5V, GND•Daisy Chain•Clock, Reset•DDC Sync signals

Analog Devices AD6620 Digital Downconverter (DDC)For narrowband signal processing

LVDS Transceiverfor daisy chain serial bus

LVDS Receivers for odd and even A/D data

Wideband signal processingon Altera Stratix FPGA

Memory board locatedOn rear of PCB

1.248 Gb/sData from

A/D



MCMS: DIF Board CapabilitiesMCMS: DIF Board Capabilities

FFSS/4 Conversion Stage /4 Conversion Stage 104 MSPS real @ 78 MHz 104 MSPS real @ 78 MHz →→ 52 MSPS complex @ 52 MSPS complex @ basebandbasebandProgrammable 63 tap FIR with 12Programmable 63 tap FIR with 12--bit coefficientsbit coefficients

Decimation by 2 Decimation by 2 Outputs 26 MSPS complex @ Outputs 26 MSPS complex @ basebandbaseband (16 bits)(16 bits)Can be bypassed (unless AD6620 DDC is to be used)Can be bypassed (unless AD6620 DDC is to be used)Programmable 46 tap FIR with 12Programmable 46 tap FIR with 12--bit coefficients bit coefficients

Digital Digital DowncoverterDowncoverter (DDC)(DDC)AD6620 input/output/control through FPGAAD6620 input/output/control through FPGAVery large decimations & fine tunings possibleVery large decimations & fine tunings possibleUser programmable through software interfacesUser programmable through software interfaces



MCMS: Serial Bus TestMCMS: Serial Bus Test

PC InterfaceData path; also controls corner turner & digital IF boards

Corner TurnerAggregates data across channels and reorders samples

Digital IF Processor

1.248 Gb/sLVDS datafrom each ADC

16-Channel Digital Backplane Four LVDS loops, each servicing 4 channels.Each loop is 320 Mb/s.



MCMS Validation: Raw A/D OutputMCMS Validation: Raw A/D Output

LabWindowsCVI Interface

Time Domain104 MSPS real(AD9432 is 12-bitso full scaleis +/-2048)

27 MHz IF input

Frequency Domain

Observed SNR is >65dB (Specification is 67dB)

Blue: 1Yellow: 100, averageYellow: 100, average



MCMS Validation: After MCMS Validation: After ↓↓FFSS/4, /4, ↓↓22

-FS/4 Spectral Shift(104 / 4 = 26 MHz)

+27 MHz shifts to +1MHz

Filter Specs:•63-tap FIR,•12-bit coeff.,•12-bit in,•16-bit out,•20 MHz LP

Frequency Domain

Time Domain52 MSPS complexOutput of Fs/4 Downconversionis 16-bits (+/-32K)




MCMS Validation: Second MCMS Validation: Second ↓↓22

Output BW is now 40/2=20MHz

Filter Specs:•31-tap FIR,•12-bit coeff.•12-bit in•16-bit out•10 MHz LP

Frequency Domain

Time Domain26 MSPS complex




MCMS Validation: DDC OutputMCMS Validation: DDC Output

DDC Filter:• Dec by 200•128-tap FIR•16-bit in•16-bit out•50 kHz LPF

Frequency Domain

Time Domain130 kSPS




Measured Output

I/F board in “Circulate Mode”• I/Q symbols (noise) @ 12.5 Mbaud

AD9857 in “Quadrature Mode”• Interpolation by 4 x 4, to 200 MSPS• NCOM upconversion to 50 MHz• Observing D/A output

GUI-based Control Software

Running in C using LabWindows/CVI

MCMS Validation : Digital MCMS Validation : Digital UpconverterUpconverter



MCMS: Data Acquisition and DSPMCMS: Data Acquisition and DSP

Dedicated Windows PCs in Dedicated Windows PCs in cPCIcPCI chassischassisBittwareBittware “Hammerhead” quad ADSP“Hammerhead” quad ADSP--21160 DSP board for on21160 DSP board for on--thethe--fly processingfly processingConnected to corner turner through 4 100Connected to corner turner through 4 100--MB/s “link port” MB/s “link port” cablescables



Project Status:Project Status:Mass build of subsystems & final assembly underway Mass build of subsystems & final assembly underway at industry partner’s facilityat industry partner’s facilityDelivery expected November 2004Delivery expected November 2004Long & extensive commissioning process to followLong & extensive commissioning process to follow

Planned First Uses:Planned First Uses:2.4 GHz x 40 MHz indoor channel meas. campaign2.4 GHz x 40 MHz indoor channel meas. campaign2.4 GHz 4 x 16 MIMO/OFDM simplex 2.4 GHz 4 x 16 MIMO/OFDM simplex testbedtestbed

Project Web Site:Project Web Site: http://www.ece.vt.edu/~swe/mcms/http://www.ece.vt.edu/~swe/mcms/

Key people:Key people: S. Ellingson, G. S. Ellingson, G. HampsonHampson (now at CSIRO), (now at CSIRO), B. Reynolds (B. Reynolds (AeroflexAeroflex), P. ), P. BohleyBohley ((AeroflexAeroflex), S. Fisher ), S. Fisher ((AeroflexAeroflex),…),…

MCMS Summary MCMS Summary



Project Status:Project Status:Mass build of subsystems & final assembly underway Mass build of subsystems & final assembly underway at industry partner’s facilityat industry partner’s facilityDelivery expected October 2004Delivery expected October 2004Long & extensive commissioning process to followLong & extensive commissioning process to follow

Planned First Uses:Planned First Uses:2.4 GHz x 40 MHz indoor channel meas. campaign2.4 GHz x 40 MHz indoor channel meas. campaign2.4 GHz 4 x 16 MIMO/OFDM simplex 2.4 GHz 4 x 16 MIMO/OFDM simplex testbedtestbed

Project Web Site:Project Web Site: http://www.ece.vt.edu/~swe/mcms/http://www.ece.vt.edu/~swe/mcms/

Key people:Key people: S. Ellingson, G. S. Ellingson, G. HampsonHampson (now at CSIRO), (now at CSIRO), B. Reynolds (B. Reynolds (AeroflexAeroflex), P. ), P. BohleyBohley ((AeroflexAeroflex), S. Fisher ), S. Fisher ((AeroflexAeroflex),…),…

MCMS Summary MCMS Summary

Anybody else want one?



Virginia Tech SummaryVirginia Tech Summary

Current MIMO Testbed Initiatives at VT:MCMS VT-STARSDR-3000

The testbeds have strong potential for research contribution in MIMO area:

MIMO measurements and validation of performance improvementDemonstration of existing air interfaces with MIMO technology

These testbeds impart significant value and greater outreach to education:

Used by students to support wireless course projectsDifferent smart antenna algorithms have been demonstrated by studentsEmphasis on programmable, software-defined hardware

mimo development efforts at virginia tech · mimo development efforts at virginia tech s. ellingson...

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