Field Measurements of 2x2 MIMO Communications March 2004 doc.: IEEE 802.11-04/263r0 March 2004 Field Measurements of 2x2 MIMO Communications Babak Daneshrad, Prof UCLA EE Dept. babak@ee.ucla.edu www.mimo.ucla.edu Babak Daneshard, UCLA Babak Daneshrad, UCLA

Overview Introduction Practical Impairments and Calibration March 2004 Overview Introduction Testbed Overview Practical Impairments and Calibration Measurement Results Babak Daneshard, UCLA

METEOR Testbed Overview March 2004 METEOR Testbed Overview Babak Daneshard, UCLA

Asteriod: The Phase-1 Testbed March 2004 Asteriod: The Phase-1 Testbed Graphical User Interface (GUI) Babak Daneshard, UCLA

UCLA Phase-2 2x2 MIMO Testbed March 2004 Testbed Components UCLA Phase-2 2x2 MIMO Testbed Memory Buffer I/O Boards Phase Locked Loop Circuit PLX Control Board Radio Freq. Circuit Babak Daneshard, UCLA

TX 2-Step RF Upconversion March 2004 TX 2-Step RF Upconversion Babak Daneshard, UCLA

RX 2 step down conversion March 2004 RX 2 step down conversion Babak Daneshard, UCLA

Calibration: SNR-in vs. SNR-slicer March 2004 Calibration: SNR-in vs. SNR-slicer Babak Daneshard, UCLA

March 2004 Calibration in AWGN Babak Daneshard, UCLA

Indoor Field Measurements March 2004 Indoor Field Measurements Babak Daneshard, UCLA

Packet Structure Packet duration = 1 ms 25 MHz bandwidth March 2004 TIME F R E Q 25 MHz bandwidth U E N C Y Acq. 1 block Training 25 blocks Pilots Unused 50 subcarriers Payload 50 blocks 206 subcarriers 20 subcarriers Babak Daneshard, UCLA

Packet Structure 1 OFDM block for Acquisition March 2004 Packet Structure 1 OFDM block for Acquisition Detects Block Boundary Estimates carrier frequency offset (rough estimate) 25 OFDM blocks for training Post FFT Channel inverse training (RLS based) During this period, fine carrier frequency offset correction (Pre-FFT method) 50 OFDM blocks payload Post FFT method for carrier frequency tracking using continuous pilots. Phase noise correction using same continuous pilots Babak Daneshard, UCLA

OFDM Parameters Number of subcarriers: 256 Cyclic Prefix: 32 March 2004 OFDM Parameters Number of subcarriers: 256 Cyclic Prefix: 32 Cyclic Postfix: 32 Total OFDM block length: 320 Unused subcarriers at DC: 18 Unused subcarriers at band edges: 32 Payload: 206 subcarriers Continuous Pilots – 20 (10% of payload) Effective bandwidth: 14.5MHz ((206subcarriers-20pilot)/320)*25MHz Babak Daneshard, UCLA

Received signal per transmission March 2004 Received signal per transmission 4-QAM packet 16-QAM 64-QAM Noise Signal Effective User rate after Stripping PHY overhead 58 Mbps 116 Mbps 174 Mbps Effective BW 14.5 MHz, Actual BW 25MHz Babak Daneshard, UCLA

Synchronization and Tracking March 2004 Synchronization and Tracking Carrier frequency synchronization Step 1: Initial estimate using the acq. block Step 2: Pre FFT method correlation of cyclic prefix and postfix Carrier frequency tracking Post FFT method Angular rotation from OFDM block to block In 1 OFDM block identical across all subcarriers Continuous pilots to estimate and correct Babak Daneshard, UCLA

IQ mismatch and Phase Noise March 2004 IQ mismatch and Phase Noise I/Q mismatch cancellation This is combined with MIMO decoding Adaptive joint channel inversion and I/Q mismatch cancellation algorithm Phase Noise cancellation Estimate phase noise with continuous pilots Forward correct phase noise Babak Daneshard, UCLA

Environment 1 Lab and Hallway March 2004 Environment 1 Lab and Hallway Transmitter location changed in 5m increments 12 antenna placements per location trms = 25 ns trms = 35 ns Babak Daneshard, UCLA

Environment 2 Cubicle Area March 2004 Environment 2 Cubicle Area trms = 38 ns to 50 ns Transmitter location changed in 5m increments 12 antenna placements per location Babak Daneshard, UCLA

Parameters 54-116 Eng IV (same room) 54-114 Eng IV (btwn rooms) March 2004 Parameters 54-116 Eng IV (same room) Line of Sight (LOS) Total Transmit Power: -3 dBm Antenna spacing at receiver: 2λ, 0.5λ, 0.25λ Antenna spacing at transmitter: fixed about 8λ Distance between Transmitter and Receiver 6-7m. 200 separate antenna locations 54-114 Eng IV (btwn rooms) Non Line of Sight (NLOS) Distance between Transmitter and Receiver about 9-10m. Babak Daneshard, UCLA

Compare SISO, SIMO1x2 and MIMO2x2 (Same Room) March 2004 Compare SISO, SIMO1x2 and MIMO2x2 (Same Room) Note: CDFs for MIMO represent SNR on one stream only 3 dB degradation in power per stream The rest is due to ill-conditioned channels & implementation loss Babak Daneshard, UCLA

Compare SISO, SIMO1x2 and MIMO2x2 (Btwn Rooms) March 2004 Compare SISO, SIMO1x2 and MIMO2x2 (Btwn Rooms) Babak Daneshard, UCLA

Measurement: Reciprocal Condition Number March 2004 Measurement: Reciprocal Condition Number Babak Daneshard, UCLA

MIMO 2x2 Antenna spacing (Same Room) March 2004 MIMO 2x2 Antenna spacing (Same Room) Babak Daneshard, UCLA

Corridor to EE54-116 Transmit Power Non Line of Sight (NLOS) March 2004 Corridor to EE54-116 Non Line of Sight (NLOS) Antenna spacing at receiver: 6λ Antenna spacing at transmitter: 8λ Range from 10m to 50m in 5m steps. Transmit Power Up to 15m -10dBm 20m-35m 0dBm 35m-50m 10dBm Babak Daneshard, UCLA

March 2004 Range Babak Daneshard, UCLA