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METEOR MIMO Experimental Testbed for OFDM Research Project funded by the ONR AINS program

METEOR MIMO Experimental Testbed for OFDM Research Project funded by the ONR AINS program. Babak Daneshrad, Prof UCLA EE Dept. babak@ee.ucla.edu www.ee.ucla.edu/~mimo (available 12/1/03). Overview. Introduction UCLA’s Unique Multidisciplinary Approach Testbed Overview

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METEOR MIMO Experimental Testbed for OFDM Research Project funded by the ONR AINS program

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  1. METEORMIMO Experimental Testbed for OFDM ResearchProject funded by the ONR AINS program Babak Daneshrad, Prof UCLA EE Dept. babak@ee.ucla.edu www.ee.ucla.edu/~mimo (available 12/1/03) Babak Daneshrad, UCLA

  2. Overview • Introduction • UCLA’s Unique Multidisciplinary Approach • Testbed Overview • Practical Impairments and Calliberation • Measurement Results • METEOR to serve the 802.11n community Babak Daneshrad, UCLA

  3. MIMO Challenges • A multidisciplinary approach is needed to effectively address the many aspects of MIMO communication system design • System & Theoretical Research • Theoretical bound on performance • Efficient algorithms for transmitter and receiver • Packet structure • Experimental Platforms • Establish bounds on practical performance • Provide feedback for theoretical modeling • Unique VLSI ASIC architectures • Delivery of 100’s of GOPS of processing power with minimal power dissipation • Novel VLSI implementation Babak Daneshrad, UCLA

  4. Industry Input Industry Input Transceivers 5.2 GHz & 2.4 GHz (25 MHz BW) Theory ASICs MIMO OFDM Mod MIMO Demod MIMO Channel Inversion MIMO FEC Non Real-Time SDR Testbed Experimental Data Real-Time FPGA + ASIC Testbed Tech Transfer Tech Transfer UCLA’s Unique Experimental Approach • Optimum solution requires free flow of information across disciplinary and academic/industrial boundaries Babak Daneshrad, UCLA

  5. Three Pronged Approach Understand SISO OFDM Comm. Complete MIMO OFDM System System Extend to MIMO Asteriod SISO/MIMO 5.3 GHz RF Off-Line Processing Comet MIMO-OFDM 5.3 GHz RF Testbed complete Big Bang MIMO-OFDM 5.3 GHz RF Real time proc. w/ ASICs Testbeds ASICs MIMO OFDM Mod. ASIC MIMO OFDM Demod ASIC Channel Decoupling ASIC FEC Encoder/decoder SASIC PUZZLE RELIC COSMER Babak Daneshrad, UCLA

  6. History of a METEOR • Jan. 2001 • Project Kickoff • Identify packet structure • Identify and order parts for transceiver, and Data Acq. • August 2002 • 30 Mbps packet mode SISO demonstrated • August 2003 • 120 Mbps 2x2 MIMO operational • RLS based channel inversion algorithms • MIMO Phase noise and IQ mismatch correction algorithms • Field trials to begin Oct 2003 • August 2004 • 480 Mbps 4x4 • Integrated MIMO OFDM Modulator ASIC • Smaller form factor with high speed DSP support • Migration to a DSP based portable platform • Nov. 2005 • Gbps real time 8x8 transmission using UCLA ASICs Babak Daneshrad, UCLA

  7. Simulated Performance MMSE vs. MMSE VBLAST Nx2N NxN MMSE NxN MMSE- VBLAST Nx4N Babak Daneshrad, UCLA

  8. RLS Error Floor vs. Training Header Babak Daneshrad, UCLA

  9. METEOR Testbed Overview Babak Daneshrad, UCLA

  10. Phase – 3 Real time MIMO OFDM based on UCLA VLSI ASICs 1 Gbps in 8x8 mode Expected: Dec. 2005 Phase – 2 Non real-time MIMO OFDM with UCLA MIMO MOD ASIC Expected: Dec. 2003 RX PC performs Off-line Synch & Demodulation RX PC TX PC TX PC Continuous Packet Transmission 70 ms Burst Captured Samples Control Control Status Updates TX RF 25 MHz BW @ 5.2 GHz TX RF 25 MHz BW @ 5.2 GHz TX RF 25 MHz BW @ 5.2 GHz RX RF 25 MHz BW @ 5.2 GHz RX RF 25 MHz BW @ 5.2 GHz RX RF 25 MHz BW @ 5.2 GHz 2 x 16 MB Buffer MIMO OFDM Mod ASIC - Real-time data modulation & packetization Testbed Evolution Phase – 1 Non real-time SISO OFDM Operational Today TX PC performs Off-line Modulation & packetization RX PC performs Off-line Synch & Demodulation 70 ms Burst Modulated Data + Control Captured Samples RX RF 25 MHz BW @ 5.2 GHz 16 MB Buffer 16 MB Buffer Babak Daneshrad, UCLA

  11. Asteriod: The Phase-1 Testbed Graphical User Interface (GUI) Babak Daneshrad, UCLA

  12. Testbed Components UCLA Phase-2 2x2 MIMO Testbed Memory Buffer I/O Boards Phase Locked Loop Circuit PLX Control Board Radio Freq. Circuit Babak Daneshrad, UCLA

  13. Graphical User Interface • Complete control over all system parameters • Packet size • Number of sub-carriers • Constellation size • Number of pilots • Number of TX and RX antennas • All internal variables are fully observable • SNR per subchannel • State of synchronization loops • BER per subchannel • Open interface for 3rd party experimentation Babak Daneshrad, UCLA

  14. TX 2-Step RF Upconversion Babak Daneshrad, UCLA

  15. RX 2 step down conversion Babak Daneshrad, UCLA

  16. Time (Length of OFDM Block) Frequency (Sub-Channel Bandwidth) A Rep. Data & Fine Sync. Coarse Load G Sync. & RLS Training & Channel Sync. Info C Estmation Frequency Domain Processing (Post FFT) (Pre FFT) Time Domain Recall Packet Structure Babak Daneshrad, UCLA

  17. Practical Impairments & Calibration Babak Daneshrad, UCLA

  18. RF Frequency Response Babak Daneshrad, UCLA

  19. Antenna Pattern Babak Daneshrad, UCLA

  20. Phase Noise & IQ Mismatch • Phase noise mitigation is critical to OFDM • IQ mismatch, gain and phase, is present in all practical RF circuits • I/Q mismatch causes interference from mirror subcarriers Babak Daneshrad, UCLA

  21. Performance Curves from Simulation Babak Daneshrad, UCLA

  22. Performance of MIMO-OFDM I/Q mismatch cancellationSimulation Curves IQ gain mismatch Tx1 - (0.75,0.90) Tx2 - (0.85,0.95) Rx1 - (0.85,1.00) Rx2 - (0.90, 0.85) IQ phase mismatch 6 degrees at both the receivers Babak Daneshrad, UCLA

  23. Bumpy Ride Even for a Wired Connection ! The Culprit: Power Supply Droop to TX PLL Boards • Transmission with linked crystals • All receiver algorithms OFF • MSE for two receivers branches shown Babak Daneshrad, UCLA

  24. CalibrationResults Babak Daneshrad, UCLA

  25. Symbol Error Rate vs input SNR (Experimental) Babak Daneshrad, UCLA

  26. Measurements Babak Daneshrad, UCLA

  27. Floor Plan of UCLA IC&S Lab Babak Daneshrad, UCLA

  28. Measurement Scenarios • Total 2x2 packets transmitted in – 275 • 55 packets transmitted in each of the following 5 scenarios • 3.3ft (1m), /2@Tx, @Rx, LOS • 10ft (3m), /2@Tx and Rx, LOS • 10ft (3m), 10@Tx and Rx, LOS • 30ft (9.1m), /2@Tx and Rx, non-LOS • 30ft (9.1m), 10@Tx and Rx, non-LOS • Each scenario consists of 4 locations with 15/15/15/10 packets transmitted at each location • For locations with 15 transmissions, there are three micro-locations with 5 packets transmitted at each Babak Daneshrad, UCLA

  29. Packet Parameters Used in Measurements • Time domain • 256 OFDM subcarriers with 22 cyclic prefix and 10 postfix • 500 OFDM data blocks and 20 training blocks for RLS training • Packet length: ~6.22ms • Frequency domain • 18 unused subcarriers at each band edge, 20 around DC • 10 synchronization pilot subcarriers • 190 (256-20-182-10) data subcarriers • Each packet carries 380,000 bits/Tx Babak Daneshrad, UCLA

  30. Measurement Results -- Channel Profile 10 transmissions Average • 30ft, /2 antenna spacing at both Tx and Rx Babak Daneshrad, UCLA

  31. Measurement Results – Condition Number • 30ft, /2 antenna spacing at both Tx and Rx 10 transmissions Average Babak Daneshrad, UCLA

  32. Measurement Results – Condition Number 10 transmissions Average • 30ft, 10 antenna spacing at both Tx and Rx Babak Daneshrad, UCLA

  33. Measurement Results – Condition Number 10 transmissions Average • 3.3ft, /2 antenna spacing at Tx,  at Rx Babak Daneshrad, UCLA

  34. Observation from the Statistics – MIMO • Line of sight (LOS) doesn’t matter when the Tx/Rx are separated by longer distance. • The SNR vs. BER performance at 30ft displays an implementaiton loss of 2.5 dB compared to simulated BER performance of MMSE in 22 Rayleigh fading channel • 3.3 (1m) Tx/Rx separation scenario is more susceptible to ill-conditioned MIMO channel, especially when Tx/Rx are in the center of the room where there is fewer surrounding objects than in the corner Babak Daneshrad, UCLA

  35. MIMO ASICs and Other Activities of Interest at UCLA Babak Daneshrad, UCLA

  36. MIMO OFDM ASIC Features • Standalone as well as FPGA supervised modes of operation • Programmability • Modulation • Data stream scrambling • 4-QAM, 16-QAM and 64-QAM • 64 pt to 1024 pt FFT in multiples of two • Packet Structure • Length of each segment of inbuilt packet structure programmable • Four distinct sync pilot modes • Variable cyclic prefix size • Override modes • External packet structures that do not fit the inbuilt packet structure format • External packet preamble for use under harsh conditions. Babak Daneshrad, UCLA

  37. HDR, PWR CONTROL PREFIX, DESCRAMBLE IFFT PACKET MIMO OFDM Transmitter ASIC • Packaged Parts received 11/6/03 • 25 mm2 chip, 0.18u CMOS technology • 1.6 million transistors • The first ever fully integrated MIMO OFDM transmitter • Implements UCLA METEOR packet structure • Support for 64 to 1024 pt FFT • Extreme programmability makes SASIC ideal for testbed purposes Babak Daneshrad, UCLA

  38. Channel Decoder ASIC Architecture • Single Channel Extended QRD-RLS • Highly regular array structure with only local communicative path, allowing easy pipelining, potential restructuring, and high throughput • Scalability for different number of transmit and receive antennas is achieved by redividing the resources accordingly • Multi-channel case can be implemented by either time-multiplexing, or in parallel, or both Babak Daneshrad, UCLA

  39. FEC -- LDPC Codes in MIMO (Brief Results) Chris Jones & Rick Wesel Electrical Engineering UCLA Babak Daneshrad, UCLA

  40. SNR Performance in Fast Rayleigh Fading 2bps 4bps rate 1/2 length 15,000 rate 1/3 length 15,000 0.5dB 3.2dB Babak Daneshrad, UCLA Length 4096 Rate ½ 3.6dB @ BER = 10-4

  41. MI Performance in Fast Rayleigh Fading In Blue, 1x1 to 4x4 Gauss Sig Cap QPSK 4x4 Cap Rate 1/2 op points Rate 1/3 op points (BER = 10-5) QPSK 3x3 Cap QPSK 2x2 Cap QPSK 1x1 Cap BPSK 1x1 Cap Babak Daneshrad, UCLA

  42. Comparing Two Techniques for Carrier RecoveryProf. Greg Pottie (pottie@ee.ucla.edu) The Pilot Tone-Aided (PTA) Approach The Cyclic Prefix-Based (CPB) Approach Babak Daneshrad, UCLA

  43. 0 10 d =0.2 d =0.2 f MSE f d =0.1 d =0.1 MSE f f b) 16-QAM d =0 d b) 16-QAM =0 -5 f 10 f -5 0 5 10 15 20 25 30 35 Cyclic Prefix Based Carrier Phase Estimator is unbiased Pilot aided approach Cyclic prefix based approach Babak Daneshrad, UCLA

  44. 4 6 2 5 7 1 BN 3 Power: 1mW 9 Power: 10mW Power: 50mW Power: 100mW 8 Slot 1 Slot 2 Slot 3 Slot 4 Slot 7 Slot 10 Slot 5 Slot 6 Slot 8 Slot 9 BN 3 10mW • 9 50mW • 4 50mW BN 7 10mW • 3 50mW • 1 50mW • 1 10mW • 2 50mW BN 3 10mW BN 7 10mW • 2 10mW • 4 10mW BN 3 10mW • 9 10mW • 1 50mW • 5 50mW • 6 1mW • 7 100mW • 9 50mW • 8 50mW • 1 10mW BN 7 10mW • 4 10mW • 5 50mW • 5 50mW Power Control Spatial-Reuse MAC DA/TDMA Prof. Izhak Rubin (rubin@ee.ucla.edu) large increase in spatial reuse factor Babak Daneshrad, UCLA

  45. Throughput Analysis of PCSA and TPA (n=10): Babak Daneshrad, UCLA

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