Slide Slide 1 1 Ellingson, Ellingson, Mostafa Mostafa , & Reed , & Reed – – Sept 19, 2004 Sept 19, 2004 Supplemental Slides: Supplemental Slides: MIMO Testbed Development at MIMO Testbed Development at the MPRG Lab the MPRG Lab Raqibul Mostafa Raqibul Mostafa Jeffrey H. Reed Jeffrey H. Reed
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Supplemental Slides: MIMO Testbed Development at the MPRG Lab · Supplemental Slides: MIMO Testbed Development at the MPRG Lab ... DSP THS1206 I1 Q1 I2 Q2 I1 Q1 I2 Q2 ... •MPRG
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Space Time Coding (STC) OverviewSpace Time Coding (STC) OverviewVirginia Tech Space Time Adaptive Radio Virginia Tech Space Time Adaptive Radio (VT(VT--STAR) description:STAR) description:
BackgroundBackgroundSpaceSpace--time codes were proposed by time codes were proposed by TarokhTarokh et. al. in the 1997 et. al. in the 1997 International Symposium on Information Theory (ISIT).International Symposium on Information Theory (ISIT).Capacity analysis of the MIMO channel was proposed by Capacity analysis of the MIMO channel was proposed by FoschiniFoschiniand and GansGans of Lucent Technologies in 1997.of Lucent Technologies in 1997.
Features of STCFeatures of STCMove diversity burden from mobile to base stationMove diversity burden from mobile to base stationDiversity advantageDiversity advantageCoding gainCoding gainIncreased bandwidth efficiencyIncreased bandwidth efficiency
mutually uncorrelated mutually uncorrelated Rayleigh fading Rayleigh fading channels channels Channel flat for one Channel flat for one block of STBCblock of STBCperfect knowledge of perfect knowledge of channel state channel state information (CSI) at the information (CSI) at the receiver receiver Total Tx power sameTotal Tx power sameRx Signal power for Rx Signal power for MRRC 3 dB more than MRRC 3 dB more than CC--STBCSTBC
Objective:Objective:To build a testbed to demonstrate the utility of MIMO techniquesTo build a testbed to demonstrate the utility of MIMO techniquesand to provide with MIMO indoor channel measurementsand to provide with MIMO indoor channel measurements
Testbed development based on software defined radio Testbed development based on software defined radio (SDR) approach for flexibility and reconfigurability(SDR) approach for flexibility and reconfigurabilityDSP processing platform for both the transmitter and the DSP processing platform for both the transmitter and the receiverreceiverImplemented MIMO technique based on Space Time Implemented MIMO technique based on Space Time Block Code (STBC)Block Code (STBC)Other MIMO techniques also possible through DSP Other MIMO techniques also possible through DSP programmingprogramming
RealReal--time data exchange (RTDX)time data exchange (RTDX)bibi--directional realdirectional real--time transfer between DSP time transfer between DSP and the host PC and the host PC
Application Layer of radioApplication Layer of radioDisplay key parameters of physical layer in Display key parameters of physical layer in MATLABMATLABCollect data for offline postCollect data for offline post--processing processing Modify a video sequence on a video EmulatorModify a video sequence on a video Emulator
Validation: Back to Back testingValidation: Back to Back testing
• The TX and RX subsystems were connected back-to-back: The DACs and the ADCs were directly connected• Channel estimates showed that direct components (h11 and h22) were much stronger than the cross components (h21 and h12): about 25 dB higher• This setup validates the system.
•MPRG DSP LAB AREA LOS and NLOS dry-wood column partition
•Durham Hall 4th Floor Corridor
•Receiver
•Transmitter
•MPRG Student’s
Cubicle Area
Lab with desks Lab with desks workbenches and workbenches and metallic shelvesmetallic shelvesLine Of Sight & Line Of Sight & Non line of sight Non line of sight (NLOS) considered(NLOS) consideredTransmitter and Transmitter and receiver placed in receiver placed in fixed locations fixed locations before before measurementmeasurement
SISO Channel: nT = 1; nR = 1 MISO Channel: nT = 2; nR = 1 SIMO Channel (SD): nT = 1; nR = 2 SIMO Channel (OC): nT = 1; nR = 2 MIMO Channel: nT = 2; nR = 2
0 10 20 30 40 50 60 70 802
4
6
8
10
12
14 VT-STAR Channel Capacity per path; nT = 2; nR = 2; Non-Line-of-Sight Measurements
Time [sec]
Cap
acity
[bps
/Hz]
Ch11
Ch12
Ch21
Ch22
CMIMO
HistogramChannel Capacity over time
A key result for flat Rayleigh fading channels (Foschini and Gans)(nT , nR): ( # of Tx. Ant., # of Rx. Ant.)H: Channel matrix of fade coefficients
SDRSDR--3000 is a versatile wideband multi3000 is a versatile wideband multi--channel transceiver channel transceiver testbed:testbed:
RealReal--time implementation of communications systemstime implementation of communications systemsBaseband algorithm development and verificationBaseband algorithm development and verificationWideband MIMO algorithm demonstrationWideband MIMO algorithm demonstrationMIMO channel measurement and characterizationMIMO channel measurement and characterization
SDRSDR--3000 offers communications system design and 3000 offers communications system design and implementation using implementation using software defined radiosoftware defined radio (SDR) (SDR) conceptsconcepts
Combines Combines XilinxXilinx VertixVertix FPGA with MPC7410 G4s in a single systemFPGA with MPC7410 G4s in a single system
Supports 4 ADC at 80MHzSupports 4 ADC at 80MHz
Supports 4 DACs at 80/160MHzSupports 4 DACs at 80/160MHz
Support high density and/or high performance software defined raSupport high density and/or high performance software defined radios dios
SDR can support 10s of separate transmit and receive channels, eSDR can support 10s of separate transmit and receive channels, each with ach with independent air interface protocol. independent air interface protocol.
Multiple air interface supported by softwareMultiple air interface supported by software
Software Communications Architecture (SCA) compliant multiSoftware Communications Architecture (SCA) compliant multi--channel channel software radio transceiver systemsoftware radio transceiver system
Now a joint project of JTRS and SDR Forum Now a joint project of JTRS and SDR Forum –– most most participants are members of bothparticipants are members of both
An attempt to develop a “universal” SDR architecture An attempt to develop a “universal” SDR architecture (five identified domains)(five identified domains)
•• Emerging standard for software radio complianceEmerging standard for software radio compliance
Still a work in progress Still a work in progress -- Currently v2.2Currently v2.2
SCASCA-- Important step to enable widespread use of Important step to enable widespread use of software radiossoftware radios
Develops an object oriented approach to radio designDevelops an object oriented approach to radio designEnables independent vendors to develop software modules that Enables independent vendors to develop software modules that are compatible with each otherare compatible with each other
3 3 cPCIcPCI--based boardsbased boardsTM1TM1--3300: Analog I/O 3300: Analog I/O board supporting 2 board supporting 2 80MHz ADCs and DACs80MHz ADCs and DACsPROPRO--3100: High speed 3100: High speed processing board with 4 processing board with 4 user programmable user programmable XilinxXilinx VirtexVirtex--II II FPGAsFPGAs, , and 1 MPC7410 and 1 MPC7410 PowerPCPowerPCProPro--3500: Signal 3500: Signal processing board with 2 processing board with 2 G4 PowerPCs and 1 G4 PowerPCs and 1 MPC7410 PowerPC for MPC7410 PowerPC for controlling the boardcontrolling the board
Implemented 802.11a based OFDM physical layer Implemented 802.11a based OFDM physical layer baseband on PRObaseband on PRO--35003500
Validated on SDRValidated on SDR--3000 using TX/RX loop back3000 using TX/RX loop back
Digital up and down conversion from base band to IF Digital up and down conversion from base band to IF tested on SDRtested on SDR--3000 through loop back.3000 through loop back.
RF front end tested through loop back.RF front end tested through loop back.
IF to RF integration in progress.IF to RF integration in progress.