1. Field Measurements of 2x2 MIMO Communications
March 2004
doc.: IEEE /263r0
March 2004
Field Measurements of 2x2 MIMO Communications
Babak Daneshrad, Prof
UCLA EE Dept.
Babak Daneshard, UCLA
Babak Daneshrad, UCLA

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

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

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

5. 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

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

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

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

9. March 2004
Calibration in AWGN
Babak Daneshard, UCLA

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

11. 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

12. 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

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

14. 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

15. 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

16. 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

17. 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

18. 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

19. Parameters 54-116 Eng IV (same room) 54-114 Eng IV (btwn rooms)
March 2004
Parameters
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
Eng IV (btwn rooms)
Non Line of Sight (NLOS)
Distance between Transmitter and Receiver about 9-10m.
Babak Daneshard, UCLA

20. 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

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

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

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

24. 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

25. March 2004
Range
Babak Daneshard, UCLA