LitePoint Confidential

L i t e P o i n t C o n f i d e n t i a l © 2 0 1 2 L i t e P o i n t , A T e r a d y n e C o m p a n y . A l l r i g h t s r e s e r v e d .

產品經理 黃丕先生

Beamforming創造產品差異化 如何最佳化測試

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Beamforming

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•  A multi-antenna signal processing technology - Combine antenna elements to form a directional ‘beam’ - Direct the signal energy in a desired angular direction

•  Two types of beamforming - Explicit – both the Beamformer and Beamformee support BF - Implicit – only the Beamformer has to support BF

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Beamforming Experiment

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•  3x3 AP as the DUT - BF on and off

•  SISO client •  802.11ac 80MHz @ 5GHz •  IxChariot running on external PC for throughput measurement

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Beamforming Experiment Setup DUT

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Throughput With vs. Without Beamforming

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Site Beamformed? RSSI (dBm)

Average (Mbps)

Max (Mbps)

Min (Mbps)

1 Yes -79 18.28 30.77 1.26

1 No -82 10.75 14.55 0.45

2 Yes -56 210.21 280.91 110.67

2 No -58 209.98 281.23 108.19

3 Yes -49 265.12 320.82 180.12

3 No -50 264.19 316.87 171.12

4 Yes -62 120.73 200.01 60.9

4 No -65 105.99 201.11 58.23

5 Yes -62 130.83 220.01 69.9

5 No -63 120.83 209.83 64.31

•  When signal is strong (~-60dBm), IBF has little benefit •  When signal is weak (~-80dBm), IBF significantly improves the throughput

>50% improvement

No significant improvement

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Better User Experience: Coverage Improvement

Normal operation mode (no BF)

BF mode

MIMO zone CDD/ BF zone

WiFi Coverage Improvement

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Implicit Beamforming: how it works

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•  Beamformer (AP) does all the work! - Acquire the uplink channel information from a normal client transmission - Apply a special Beamformer matrix to convert the uplink to downlink channel - Use the downlink channel and beamform to the client direction

•  Pros - Transparent to Beamformee (client), hence support legacy client devices - No signaling overhead to setup beamforming

•  Cons - Not as accurate as explicit beamforming, hence the performance is limited

Start DL BF

… Repeat

Estimate UL channel

Beamformer Beamformee

Normal transmission

Convert to DL channel

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Implicit Beamforming: what need to be tested

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•  Test requirements - Calibration: special routine required to calibrate phase and gain difference

for each Beamforming chain (due to PA, switch, FEM difference in each chain). This needs to be done on every DUT as Beamforming is sensitive to shift in phase and gain that varies from DUT to DUT

- Verification: compare received power difference between BF and non-BF

•  Supported on the IQxel family through IQfact+

Special calibration required

3x3 chip

DUT

Rx

Rx

Rx

Tx

Tx

Tx

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Explicit Beamforming: how it works

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•  Both Beamformer and Beamformee need to support beamforming - Run a training sequence before beamforming - This sequence is carried out periodically as the channel is not static

•  Pros - Accurate DL channel information, hence the best BF performance

•  Cons - BF have to be supported by both Beamformer and beamformee, hence not

compatible with legacy devices - BF training overhead

BF Sounding packets Channel estimation [H]DL

Return BF report

Start DL BF …

Repeat

Periodic

Beamformer Beamformee

Apply [H]DL Generate BF report

Decode BF report

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Explicit Beamforming: what need to be tested

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•  Test requirements •  Calibration: no special requirement •  Verification: Beamformer, Beamformee or both (if supported by DUT)

need to be verified separately. The tester has the ability to emulate Beamformer and Beamformee, and can also manipulate the channel (V matrix)

•  Supported on the IQxel family

NDPA NDP

SIFS

Sounding Feedback SIFS

IQxel TX

DUT TX

NDPA NDP

SIFS

Sounding Feedback SIFS SIFS

BF packet … BF packet

IQxel TX

DUT TX

Beamformee test:

Beamformer test:

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LitePoint Solution

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IQxel-M8: High Volume Connectivity Test Solution

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•  High throughput enabled by advanced system architecture •  Packet Engine™ optimizes testing of packet-based technologies •  Build in multi-DUT test capability to minimize DUT control time •  Synchronous and/or asynchronous test flows

•  Comprehensive technology coverage •  WiFi a/b/g/n/p/ac •  BT v1 to 4.2 •  802.11ah, ZigBee, DECT

•  Manufacturing simplicity •  Fully calibrated, internal signal path routing – no external switches needed •  Per-port level control – compensates for DUT to DUT path loss variation •  Support factory efficiency features

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Flexible Figuration for SISO/MIMO/IBF Test

1 2 3 4

•  4 DUT 2x2 true MIMO/IBF

•  8 DUT SISO

1 2 3 4 5 6 7 8

•  8 DUT composite MIMO/IBF

1 2 3 4 5 6 7 8

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High Throughput through Multiple Methods

Advanced Test Methods through Standards Knowledge

Test multiple Devices in Parallel

. . .

Deep IC knowledge and partnerships drive new Test Methods

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Turn-key solution to optimize throughput, enable fast production

ramp and minimize software development effort

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Built for the Tough Factory Environment

Rugged design. Torque-tolerant N-type RF

connectors

Low power consumption and efficient cooling for operation in

hot factory environment.

Simple user interface. Minimizes operator training,

enhance reliability.

Factory efficiency features to simplify maintenance and

improve yield

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