Over The Air Performance Test System. Employing Reverberation Chamber

Transcription

1 IEICE Technical Committee on Antennas and Propagation1 Over The Air Performance Test System for MIMO Antennas Employing Reverberation Chamber ::::::: 22 nd May, 2009 ::::::: Daisuke KURITA Yoshiki OKANO Shin NAKAMATSU Takashi OKADA NTT DOCOMO

2 Outline 2 Background Requirement and subject for MIMO OTA using reverberation chamber Proposed MIMO OTA test system Study on MIMO OTA test system Wall antenna switching condition Delay spread varying with load objects condition in chamber Verification of test for mobile phone MIMO antennas Monopole array antenna Mobile phone antenna model Summary

3 Background 32 [Multi-antenna technology for mobile system] - Rx-diversity and MIMO will be introduced to enhance higher peak data rate of mobile phone system, such as HSPA+, LTE, and 4G 4G MIMO data rate largely depends on MIMO antenna property. Peak data rate WCDMA Enhancement HSDPA HSPA+ MIMO technology LTE Characterization of MIMO antenna performance is indispensable to radio network design. Simple and repeatable MIMO antenna OTA testing system is required. Study item of MIMO OTA discussion in 3GPP has been started.

4 Requirement of MIMO OTA test system 4 OTA Testing Throughput Performance Angle Spread Simple Configuration Passive Measurement DUT DUT External Feeding Antenna Gain Plane wave Active Measurement Applicable? Internal Feeding Throughput Angle spread Our target is to establish multi-antenna OTA measurement system utilizing existing standard OTA measurement system for single-antenna evaluation.

5 Previous Study 5 Multi antenna OTA test system for Rx diversity employing reverberation chamber has been proposed. Wall Antenna Radio Communication Analyzer Platform Stirrer DUT Plate Stirrer GPIB RS232C Control PC Multi-antenna measurement system employing reverberation chamber FEATURE Reverberation chamber - Enables OTA testing - Considering angle spread - High accuracy & repeatability - High speed measurement - Based on existing single antenna OTA measurement system Objective of this study : Expanding for MIMO (using multi-stream signal) OTA test

6 Current Study and Study Items MIMO OTA test systems using reverberation chamber have been presented. WLAN MIMO throughput test in reverberation chamber (IEEE AP-S) MIMO OTA testing based on reverberation chamber (3GPP RAN4) 6 - WLAN AP and client are located inside of the reverberation chamber Merit Demerit MIMO OTA testing with throughput Difficult to control signal level Ref.) N. Olano, C. Orlenius, K. Ishimiya, and Z. Ying. WLAN MIMO throughput test in reverberation chamber, IEEE AP-S International Symposium, San Diego, CA, July BS is located outside of the reverberation chamber Merit Enables us to control signal level Ref.) 3GPP Contribution, TSG RAN WG4 Meeting #51 R , MIMO OTA testing based on Reverberation Chamber Technique, Vodafone Group. Study Item 1 : Wall antenna condition (Rx-diversity) Switched -> (MIMO OTA) Fixed is necessary Study Item 2 : Throughput don t depend on only antenna property but also delay spread varied by number of load objects Verification is carried out

7 Proposed MIMO OTA Test System 7 W-LAN Access Point FEATURE - Enables MIMO OTA testing - Considering angle spread - High accuracy & repeatability - High speed measurement - Based on existing single antenna OTA measurement system Client PC W-LAN Client RS232C Server & Control PC MIMO antenna measurement system employing reverberation chamber Study Item - Wall antenna assignment 2 streams -> 3 wall antennas - Delay spread Depends on volume of load MIMO OTA test system using reverberation chamber is established

8 Outline 8 Background Requirement and subject for MIMO OTA using reverberation chamber Proposed MIMO OTA test system Study on MIMO OTA test system Wall antenna switching condition Delay spread varying with load objects condition in chamber Verification of test for mobile phone MIMO antennas Monopole array antenna Mobile phone antenna model Summary

9 Verification of MIMO OTA Test System 9 Wall ANT #3 Wall ANT #1 Wall ANT #2 RS232C Stream A Stream B W-LAN Access Point Server & Control PC [Employed system] - MIMO-enabled wireless LAN - IEEE n draft version - Frequency : 2.45 GHz Load Monopole Array Antennas UP Link Vector Signal Analyzer Antenna performance - Received power - Correlation W-LAN Client Control PC Transmission Performance - Throughput (TCP) - Separate DUT into antenna part and other part (RF circuit, BB, etc.) -> Antenna property and throughput can be evaluated simultaneously

10 Demonstration 10 Received power (Rx #1) Correlation Reverberation Chamber Received power (Rx #2) Throughput Antenna property and throughput can be evaluated simultaneously

11 Wall Antenna Switching Condition 11 Dual stream of MIMO signal is input into 2 of 3 wall antenna > Verified using throughput and CDF of received power WA1 StA/WA2 StB WA2 StA/WA3 StB WA3 StA/WA1 StB Throughput Rx-Power ANT#1 ANT# Throughput (Mbps) V-V H-H V-H Configuration of monopole array antenna Throughput and received power Normalized Received Power (db) Cumulative Probability Wall ANT #3 Wall ANT #1 CDF of received power Wall ANT #2 3 Wall Antennas Wall Antenna #1 Wall Antenna #2 Wall antenna #3 Rayleigh Fading (Cal) Received Power (dbm) - Throughput : Independent on Wall/Rx antennas - CDF : Rayleigh distribution at each wall antenna MIMO signal can be input into fixed wall antenna

12 Delay Spread Condition in Reverberation Chamber 12 Delay spread can be controlled by changing number of load object > Verified using delay spread and throughput at each load condition No-Object Cylinder SAM Phantom small Load Cylinder +SAM x2 Cylinder +SAM x3 Large 100% Frequency (%) 80% 60% 40% 20% 0% Relative Delay (nsec) Throughput (Mbps) Normalized throughput with SIMO Histogram of delay spread Throughput - Delay spread : Smaller with increasing load object - Throughput : Closer ideal with increasing load object Enough number of load is necessary

13 Outline 13 Background Requirement and subject for MIMO OTA using reverberation chamber Proposed MIMO OTA test system Study on MIMO OTA test system Wall antenna switching condition Delay spread varying with load objects condition in chamber Verification of test for mobile phone MIMO antennas Monopole array antenna Mobile phone antenna model Summary

14 Verification Based on Monopole Array 14 Comparing OTA results corresponding to imbalance and correlation with that for conducted results OTA Conducted - Emulating channel condition using a fading simulator (Fading model : 2path Rayleigh) - Applying Rx power and correlation observed in OTA test Throughput (Mbps) Signal level : High Signal level : Low Antenna Imbalance (db) Throughput (Mbps) Signal level : Low Signal level : High Correlation - MIMO antenna property : Impact on throughput - OTA and conducted throughput difference : 6.1% (Average) Good Agreement

15 Verification Based on UE Antenna Model 15 UE antenna radiation pattern : Complicated > Verified using UE antenna model Top(T) Antenna Hinge(H) Antenna Bottom(B) Antenna Metal Plate Metal Plate Antenna configuration - Top & Hinge - Top & Bottom - Hinge & Bottom Phantom hand Antenna Efficiency (db) Top & Hinge Top & Bottom Hinge & Bottom Top & Hinge (w.hand) Correlation With phantom hand Antenna performance Structure of UE antenna model (Clam shell model)

16 Throughput Performance with Different Antennas 16 - Comparing OTA results corresponding to antenna configuration and using hand phantom or not with that for conducted results OTA Cond. Top & Hinge Top & Bottom Hinge & Bottom OTA Cond. w/o Hand phantom with Hand phantom Throughput (Mbps) Throughput (Mbps) T&H T&B H&B T&H T&B H&B 30 w/o with w/o with High Signal Level Low High Signal Level Low Antenna configuration With/without hand phantom - MIMO antenna efficiency : Impact on throughput - OTA and conducted throughput difference : 5.5% (Average) Good Agreement

17 Summary 17 MIMO OTA test system using reverberation chamber is proposed and presented Subject of MIMO OTA test system is studied 1. Wall antenna switching condition - Throughput : Independent on Wall/Rx antennas MIMO signal can be input - CDF : Rayleigh distribution at each wall antenna into fixed wall antenna 2. Delay spread varying with load objects condition in chamber - Delay spread : Smaller with increasing load object Enough number of - Throughput : Closer ideal with increasing load object load is necessary Verification of testing mobile phone MIMO antennas - MIMO antenna property : Impact on throughput Good - OTA and conducted throughput difference : 6.1% (Average) Agreement - Validity of proposed OTA test system has been confirmed -