LTE-U Technology and Coexistence - LTE-U Forum

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May 28, 2015 - spectrum as a Supplemental Downlink to LTE technology operation using ... ANY PARTICULAR PURPOSE, AND ALL
Qualcomm Technologies, Inc.

LTE-U Technology and Coexistence May 28th, 2015

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Disclaimer and Copyright Notification Copyright © 2015 LTE-U Forum Companies: Alcatel-Lucent, Ericsson, LG Electronics, Qualcomm Technologies Inc., Samsung Electronics, Verizon. All rights reserved. This document provides initial information related to Long Term Evolution (LTE) technology operation using unlicensed spectrum as a Supplemental Downlink to LTE technology operation using licensed spectrum. All information provided herein is subject to change without notice. The information provided herein was considered technically accurate by the LTE-U Forum Companies at the time the documents were initially published, but LTE-U Forum Companies disclaim and make no guaranty or warranty, express or implied, as to the accuracy or completeness of any information contained or referenced herein. LTE-U FORUM COMPANIES DISCLAIM ANY IMPLIED WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT, OR FITNESS FOR ANY PARTICULAR PURPOSE, AND ALL SUCH INFORMATION IS PROVIDED ON AN “AS-IS” BASIS. Other than as explicitly provided below, LTE-U Forum is not providing any licenses under any intellectual property of any kind owned by any person (whether an LTE-U Forum Company or otherwise) that may be necessary to access or utilize any of the information contained herein, including but not limited to any source materials referenced herein, and any patents required to implement or develop any technology described herein. It shall be the responsibility of the developer to obtain any such licenses, if necessary. LTE-U Forum disclaims liability for any damages or losses of any nature whatsoever whether direct, indirect, special or consequential resulting from the use of or reliance on any information contained or referenced herein. Permission is given to reproduce this document in its entirety solely for the review, analysis, and implementation of LTE-U. Use of this document for any other reason without the permission of LTE-U Forum Companies is explicitly prohibited. ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Outline • Overview of LTE-U coexistence algorithms design − Channel selection, CSAT and OSDL − How to coexist with Wi-Fi BSSs within and outside CCA-ED

• Lab & OTA results for coexistence above and below CCA-ED − Different traffic applications − Wi-Fi/Wi-Fi, Wi-Fi/LTE-U fairness study

• Demos − Stress room demo with three different Wi-Fi AP vendors − OTA on-campus demo with two different Wi-Fi AP vendors ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Introduction • Throughout the LTE-U design and testing, coexistence has been a main principle that has been studied thoroughly with different applications, devices, and deployment models • We couldn’t rely just on 802.11 spec due to divergence by many implementations − Wi-Fi benchmark based on testing of Wi-Fi AP and chip vendors with the highest market shares

• What is presented here is Qualcomm’s design in accordance with LTE-U Forum spec − The spec provides guidelines and testing scenarios to be passed but doesn't dictate specific implementations − This is obviously not the only way for implementation

• The design covers a larger set of scenarios than those mandated by spec

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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LTE-U Coexistence Solutions State Diagram Initialization & Configuration

Channel Selection (ChS) Triggered by channel switch condition

CSAT Enabled

LTE-U UE added (or high traffic load)

No LTE-U UE (or low traffic load)

OSDL (LTE-U Off) ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Channel Selection Wi-Fi AP UE3 Wi-Fi AP UE2 STA Co-located LTE-U SC/Wi-Fi AP

UE1

Wi-Fi AP

LTE-U and WiFi NL(Network Listening) assisted with UE reporting LTE & Wi-Fi measurements and CQI/BLER to detect hidden nodes

LTE-U SC

LTE-U SC

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Channel Penalty Function

δ1

Wi-Fi AP Beacon RSSI Measurements, and whether channel is primary or secondary

LTE-U UE WiFi Measurements over RRC

× δ2

× δ3

LTE-U NL Measurements

×

+

Total Channel Penalty

δ4 LTE-U UE RRM measurements

× δ5

LTE-U UE CQI/ BLER

×

• Different penalty weighting for different interference sources, e.g. WiFi primary channel has higher penalty compared to secondary channel • Quantized penalty for robustness to measurement errors and to reduce bias due to outliers • Measures % of coverage area with some desense due to other AP interference • Built in mechanisms to detect and mitigate frequent channel switching ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Channel Selection- Summary 1. 2. 3. 4.

• • • • •

Has to be both during initial boot up as well as dynamically during operation Choose the cleanest channel in general If possible avoid primary channels of WiFi If possible avoid channels occupied by other LTE-U operators and choose channel occupied by the same LTE-U operator (Forum coexistence spec 6.1.2) Channel selection is aided by Small Cell NL(Network Listening) and/or UE measurements Can be done through passive or active scan- our design uses active Scanning typically happens every few seconds Channel selection can happen at any time, but typically within 10s seconds Channel selection is conservative in that it considers any found beacon to be active − Taking channel loading in consideration is for further optimization ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Carrier Sense Adaptive Transmission (CSAT) • A TDM transmission pattern on the LTE-U SCell with TCSAT cycle

− This pattern leverages existing LTE carrier aggregation MAC signaling ( MAC control element for activating and deactivating an SCell) − This pattern is triggered based on transmissions measured from Wi-Fi APs

• Wi-Fi medium utilization measurement is performed during LTE-U SCell OFF time, to adjust ON/OFF duty cycle − Adaptive trade-off between LTE-U and other systems (e.g. Wi-Fi) performance.

Gating Cycle (TCSAT) LTE-U ON

LTE-U OFF

Ton /Toff adaptive

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Wi-Fi Medium Utilization (MU) Estimation Input to CSAT loop • Wi-Fi MU monitoring is done where all LTE-U small cells are required to turn 5GHz RF transmission OFF in this period − guarantees overlapping OFF time across neighbor LTE-U small cells for sensing Wi-Fi

• Sensing time is selected sufficiently large to allow the co-located Wi-Fi NL module for reliable MU monitoring of the operating channel. MU is also averaged across multiple observations • Wi-Fi NL decodes the preamble of any WiFi packet detected during this time and records its corresponding received signal strength indicator (RSSI), duration in μs (or NAV), modulation, coding scheme (MCS) and source/destination address

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Wi-Fi MU Estimation Averaged weighted observed activity over a monitoring window • The algorithm divides packets into different categories based on their attributes and each category is assigned a weight • If the packet is found to be an ACK, or CTS, and the preceding data packet is not detected, the packet is classified as generated from a hidden node and count the packet as full duration (nominal value of around 4msec) • Let Wi and Di denote the weight and duration of i-th detected packet during MU monitoring time, assume that K packets were detected during the monitoring time. The instantaneous MU is computed as 𝐾𝐾

1 � 𝑊𝑊𝑖𝑖 × 𝐷𝐷𝑖𝑖 𝑀𝑀𝑀𝑀(𝑛𝑛) = 𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀

• WiFi medium utilization is filtered as follows:

𝑖𝑖=1

𝑀𝑀𝑀𝑀 𝑛𝑛 = 𝛼𝛼𝑀𝑀𝑀𝑀 𝑀𝑀𝑀𝑀 𝑛𝑛 + 1 − 𝛼𝛼𝑀𝑀𝑀𝑀 𝑀𝑀𝑀𝑀 𝑛𝑛 − 1 where filter coefficient 𝛼𝛼𝑀𝑀𝑀𝑀 could be set small for smaller monitoring time to allow more averaging

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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CSAT Adaptation Outer loop to decide on Ton in a given CSAT cycle • CSAT algorithm will increase/decrease 𝑇𝑇𝑂𝑂𝑂𝑂 if MU is below/above a certain threshold

• CSAT adaptation is done as follows:

𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 + 1 = m𝑖𝑖𝑖𝑖 𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 + ∆𝑇𝑇𝑈𝑈𝑈𝑈 , 𝑇𝑇𝑂𝑂𝑂𝑂,𝑚𝑚𝑚𝑚𝑚𝑚

where

𝑖𝑖𝑖𝑖 𝑀𝑀𝑀𝑀 𝑛𝑛 < 𝑀𝑀𝑀𝑀_𝑇𝑇𝑇𝑇𝑇1

𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 + 1 = 𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 𝑖𝑖𝑖𝑖 𝑀𝑀𝑀𝑀_𝑇𝑇𝑇𝑇𝑇1 ≤ 𝑀𝑀𝑀𝑀(𝑛𝑛) ≤ 𝑀𝑀𝑀𝑀_𝑇𝑇𝑇𝑇𝑇2 𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 + 1 = m𝑎𝑎𝑎𝑎 𝑇𝑇𝑂𝑂𝑂𝑂 𝑛𝑛 − ∆𝑇𝑇𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 , 𝑇𝑇𝑂𝑂𝑂𝑂,𝑚𝑚𝑚𝑚𝑚𝑚 𝑖𝑖𝑖𝑖 𝑀𝑀𝑀𝑀 𝑛𝑛 > 𝑀𝑀𝑀𝑀_𝑇𝑇𝑇𝑇𝑇2

− 𝑇𝑇𝑂𝑂𝑂𝑂,𝑚𝑚𝑚𝑚𝑚𝑚 bounds LTE-U ON interval to ensure LTE-U receives a fair share of the medium − 𝑇𝑇𝑂𝑂𝑂𝑂,𝑚𝑚𝑚𝑚𝑚𝑚 bounds LTE-U OFF interval to allow time to sense Wi-Fi activity − ∆𝑇𝑇𝑈𝑈𝑈𝑈 and ∆𝑇𝑇𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 determine the convergence speed of CSAT adaptation

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Adjust TON,min for Fairness Selecting TON,min independent of the number of neighbor Wi-Fi APs and LTE-U SCs might result in unfair resource sharing. To mitigate this issue, TON,min is selected as below after every AP scan: 𝑇𝑇𝑂𝑂𝑂𝑂,𝑚𝑚𝑚𝑚𝑚𝑚 where − − − −

𝑁𝑁 + 1 × 𝑇𝑇𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 = 𝑚𝑚𝑚𝑚𝑚𝑚 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇, 𝑁𝑁 + 1 + 𝑀𝑀 + 𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁

𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 is a configurable parameter controlling minimum duty cycle below ED N is the number of LTE-U SCs with the same PLMN ID measured by the specific LTE-U SC M is the number of LTE-U SCs with different PLMN ID Number of Wi-Fi Devices (how to weigh in STA activity (visible to the algorithm) is still being optimized) − Always go 1/num_of_Tx vs 1/num_APs vs a mix

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Protecting Latency Sensitive WiFi Applications - Subframe Puncturing Gaps inside Ton • Subframe puncturing introduces frequent gaps in the LTE-U ON duration to help Wi-Fi flush delay-sensitive data and management packets that may be queued at the AP because of LTE-U transmissions • In the specified punctured pattern, the subframes which are punctured are not used for scheduling any data • Typically few msec every few 10s of msec (2/20msec is typical) eNB Tx Power

Few ms SF puncturing every 20ms

TON 80ms

Example: Punctured CSAT Waveform TOFF 80ms 20ms

Tim e

• Another way to accommodate latency sensitive applications is to run short CSAT cycles − Recent design allows LTE-U to go to as low as 20msec of Ton ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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CSAT Cycles • Typical CSAT cycles − 80msec total ON/OFF duration (i.e. like 40/40) & 160msec (i.e. like 80/80msec)

• CSAT cycles on primary WiFi channel are typically shorter to enable beacon transmissions and connection setup activities • In general CSAT cycles are constant but can change in scenarios where LTE-U share is too small − i.e. 10% LTE-U share may be 40msec/360msec as opposed to 10msec out of 100msec

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Benefit of WiFi NL Not fundamental

• Most coexistence functionalities can be achieved without NL albeit more complexity and less optimal trade-offs • Examples: − NL can help though reacting to some less common scenarios like hidden nodes − NL may allow better tradeoff of coexistence since it allows distinction between one node vs multiple nodes when both scenarios show same medium activity − NL allows distinction between LTE-U and WiFi nodes allowing the ability to run reuse 1 if need be on the former ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Lab and OTA Testing

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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LTE-U / Wi-Fi Coexistence Setup • Extensive lab test on LTE-U coex − Wi-Fi: Multiple AP and STA brands − LTE-U: Test eNB and UE MTP

• Current focus: Non-LBT/CSAT design

CSAT Wi-Fi Testing Logical Setup Diagram

TBS eNB

− LBT-based test depend on 3GPP progress − Key Non-LBT coex feature is CSAT − CSAT has dynamic duty cycle, max 100-ms ON time, and long + shortPL OFF gaps PCell − Note LTE-U coexistence in reality would be better with proper channel selection

APUT

FC PLeNB,APUT PLeNB,UE

eNB,UE

• Cabled-up test in controlled environment − 80 MHz max bandwidth assumed for Wi-Fi − LTE-U on one of secondary channels of Wi-Fi

AP

PLAPUT,AP

PLeNB,STAUT

PLAPUT,STAUT

SCell

PLAPUT,STA

PLAP,STA

PLAP,STAUT PLSTAUT,STA

FC

LTE-U UE

STAUT

STA

1x1 AWGN Cabled Up, 802.11ac, 80 MHz

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Full Buffer TCP Throughput Results (Below ED) Below ED AP ID

CINR

TCP Throughput

1

0 dB

0.9x

1

5 dB

1.1x

1

15 dB

1.8x

2

0 dB

0.9x

2

5 dB

0.95x

2

15 dB

1.85x

Baseline throughput = x (50% of isolated Wi-Fi throughput – optimistic assumption) CINR = Wi-Fi signal energy / LTE signal energy at Wi-Fi STA

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Wi-Fi YouTube Streaming Results – Wi-Fi/Wi-Fi vs. Wi-Fi/LTE-U Below ED AP 1 Metrics

Baseline (w/ Wi-Fi)

AP 2

w/ LTE-U

Baseline (w/ Wi-Fi)

w/ LTE-U

No. of video stalls

6.00

1.67

12.33

2.67

Playback interrupt time (s)

7.94

7.40

4.77

2.00

Initial Buffer Time (s)

0.67

1.33

0.33

0.33

Avg. Thpt (Mbps)

3.49

4.49

3.17

5.89

Avg. PHY Rate (Mbps)

19.81

39.88

65.65

83.55

LTE-U hit is an erasure LTE-U with CSAT is a better neighbor than Wi-Fi ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Overview of OTA Campus Network OTA Campus Network

WB LTE-U eNB

WC Wi-Fi AP1 (Above CCA-ED)

Wi-Fi AP2 (Below CCA-ED)

Inset Video Footage

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Carrier Wi-Fi VoIP: Primary CH, Above ED, 160msec CSAT, 2/20 Puncturing

AP backs off for energy during the LTE-U ON period except for gaps in the waveform provided by MBSFN when packets are flushed.

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Carrier Wi-Fi VoIP: Primary CH, Below ED, 160ms CSAT, 2/20 Puncturing Sequence Number Time Trace

2645

Sequence Number

2640

2635

VoIP packets sent during gaps in the CSAT ON duration

2630

2625

CSAT OFF duration 2620

2615 13.3

13.4

13.5 Time (s)

13.6

13.7

13.8 ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Carrier Wi-Fi VoIP: Primary CH, 160ms CSAT, 2/20 MBSFN • Wi-Fi VoIP Calling Statistics† Scenario

|Jitter| > 50ms

Packet Loss

> 3 Consec. Packet Loss

Above ED

6.6%

1.1%

0.1%

Below ED

1.0%

0.7%

0.0%

DL VoIP Packet-to-Packet Jitter CDF

DL VoIP Cycle-to-Cycle Jitter CDF

1 0.9

1 Primary CH, Below ED Primary CH, Above ED

0.9

0.8

0.8

0.7

0.7 0.6

0.5

CDF

CDF

0.6

0.4

0.5 0.4

0.3

0.3

0.2

0.2

0.1 0 -60

Primary CH, Below ED Primary CH, Above ED

0.1 -40

-20 0 20 DL VoIP Packet-to-Packet Jitter (in ms)

40

60

0 -60

†Calculated per WFA-VE guidelines; Packet arrival one approx. every 20ms

-40

-20 0 20 DL VoIP Cycle-to-Cycle Jitter (in ms)

40

60

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Carrier WiFi VOIP: Secondary CH, Below ED, 640ms CSAT, 2/20 MBSFN DL Data Rate Time Trace 30

Smart BW mgmt. forces VoIP to go on the clean primary channel for PER. No degradation in voice quality.

DL Data Rate (Mbps)

25

DL Packet BW CDF 1

20

15

0.9

10 0.8 0.7

5 0

0.6

1

2

3

4

5 Time (s)

6

7

8

9

10

0.5

93.1% of the time packets are sent on the primary 20MHz channel.

0.4 0.3 0.2 0.1 0 0

5

10

15

20 DL Packet BW

25

30

35

40

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Fast CSAT: Low latency MAC Activation/Deactivation • MAC CE for activation is sent xms before start of on time • If deactivation time (Toff) is < Thr, UE is expected to be ready to decode PDCCH in 1-2ms (short cDRX behavior)-no minimum 8ms for activation as in spec • MAC CE for deactivation is sent before end of Ton • Error events of losing or misinterpreting activation/deactivation have to happen ith low probability by design (to the level the can be handled and absorbed by UE tracking loops) CRS ON or Ton

CRS OFF or Toff δ

MAC CE Activation

MAC CE Deactivation

MAC CE Activation

Ton

Activation Overhead

MAC CE Deactivation

Time UE is ready fro grants

• To be accompanied with sending CTS2S with MAC activation after contention − To protect against BI − To protect WiFi rate control ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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Stress Room Testing

27

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Stress Test Chamber

28

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Stress Test Chamber Setup AP is inside RF shielded box

1 WiFi AP and 1 LTE-U node under test

AP1

AP2

AP3

AP4

STA1

STA2

STA3

STA4

− The WiFi AP-UT is inside an RF shielded box

8 Reference WiFi nodes − 4 APs inside RF box to allow below ED scenarios

3 Enterprise grade WiFi APs + Controller − Referred to as Vendor A, B, and C

AP under test

Gigabit Ethernet switch

STA under test

STA8

STA7

STA6

STA5

AP8

AP7

AP6

AP5

Results presented in these slides − All links above CCA-ED − 8WiFi+WiFi vs. 8WiFi+LTE-U − LTE-U duty cycle = 1/9

29

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Summary (Vendor A) LTE-U outperforms Wi-Fi 6.7 5.8

Wi-Fi

Baseline

LTE-U maintains Wi-Fi performance 6.6

6.8

Wi-Fi

Wi-Fi

Baseline

CSAT

LTE-U LTE-U

CSAT

Unit Under Test Unlicensed throughput

Average Wi-Fi throughput 30

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Summary (Vendor B- more aggressive in winning medium) LTE-U outperforms Wi-Fi

LTE-U maintains/improves Wi-Fi performance

6.6 4.8

Wi-Fi

Baseline

LTE-U

4.9 3.9

LTE-U

CSAT

Unit Under Test Unlicensed throughput

Wi-Fi

Wi-Fi

Baseline

CSAT

Average Wi-Fi throughput

31

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Screenshot (Mixture of Vendor A and B)

Stress Test: 8 Wi-Fi + LTE-U

Baseline: 8 Wi-Fi + Wi-Fi

Vendor B

Vendor A

32

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Summary (Mixture of Vendor A and B) LTE-U outperforms Wi-Fi 6.7 LTE-U 1.9 Wi-Fi Baseline (A)

LTE-U

CSAT

Unit Under Test Unlicensed throughput

LTE-U maintains Wi-Fi performance 5.8

5.8

Wi-Fi

Wi-Fi

Baseline

CSAT

Average Wi-Fi throughput

33

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Screenshot (Mixture of Vendor A and C)

Stress Test: 8 Wi-Fi + LTE-U

Baseline: 8 Wi-Fi + Wi-Fi

Vendor A

Vendor C

34

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Demo GUI Summary (Mixture of Vendor A and C) LTE-U outperforms Wi-Fi 7.1 4.5 Wi-Fi

Baseline

LTE-U maintains Wi-Fi performance 6.6

6.7

Wi-Fi

Wi-Fi

LTE-U LTE-U

CSAT

Unit Under Test Unlicensed throughput

Baseline

CSAT

Average Wi-Fi throughput

35

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Summary of Stress Room Testing Main Observations

In general LTE-U preserves or enhances Wi-Fi user experience If Wi-Fi nodes are fair in medium sharing, LTE-U gains are lower, as its link level gains are not exposed by this dense setup If Wi-Fi nodes are aggressive in medium occupancy, frequent collisions occur and LTE-U provides better user experience for WiFi nodes by deterministically clearing the medium after its fair share decreasing relative number of collisions − LTE-U gains over Wi-Fi are more pronounced in this case and mostly due to MAC 36

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Fairness Testing

37

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Introduction to fairness study We studied how different Wi-Fi APs coexist with each other − Later compared to coexistence with LTE-U as well

Conducted measurements using commercially available Wi-Fi Certified WLAN devices − 5 top-selling retail APs (11ac) based on ‘best-seller lists’ determined from top industry magazines and online-retailers − Product diversity of 5 OEMs and 3 chipset-vendors − Labelled – A thru E

− STA (11ac, 1x1) – a top-selling mobile-device − Same brand of STA device used with all APs to limit combinations 38

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Test Setup Four Networks with 1 AP having 1 STAs each − All APs set to VHT20 in Ch#153 − All combinations of APs from set of 5 considered

Both APs are doing fullbuffer downlink traffic (iperf) to the STAs Average throughput determined over a 90sec period

RF Screen Room STA1

Traffic Source

AP1

STA2

AP2

Traffic Source

STA3

Traffic Source

AP3

STA4

AP4

Traffic Source

39

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Test Results

Different APs achieve different levels of throughput share Wide variation in channel aggregate throughput of different devices despite similar link conditions (high SNR regime)

40

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Fairness between Wi-Fi/Wi-Fi and Wi-Fi/LTE-U Test Setup AP1

STA1

STA under test

AP under test

Gigabit Ethernet switch

Tests are performed using two Wi-Fi connection pairs across different AP models, and one LTE-U link with one Wi-Fi AP link across different AP models 41

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Consumer grade Fairness with and without LTE-U (Air time) Testing pair-wise airtime sharing across 4 Wi-Fi AP models and between Wi-Fi/LTE-U

Duty Cycle Cycle CDF Duty

1 0.9 0.8

W in 1W+1W W in 1W+1L L in 1W+1L

0.7

CDF

0.6 0.5 0.4

• Points corresponding to coexistence with AP model A • AP model A does not obey CCA-ED rule and does not backoff to LTE-U Points corresponding to all 4 Wi-Fi AP models

0.3 0.2 0.1 0 0

10

20

30

40 50 Percentage

60

70

80

90

42

©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

Thank you Follow us on: For more information, visit us at: www.qualcomm.com & www.qualcomm.com/blog ©2013-2015 Qualcomm Technologies, Inc. and/or its affiliated companies. All Rights Reserved. Qualcomm is a trademark of Qualcomm Incorporated, registered in the United States and other countries. All trademarks of Qualcomm Incorporated are used with permission. Other products and brand names may be trademarks or registered trademarks of their respective owners. References in this presentation to “Qualcomm” may mean Qualcomm Incorporated, Qualcomm Technologies, Inc., and/or other subsidiaries or business units within the Qualcomm corporate structure, as appli . Qualcomm Incorporated includes Qualcomm’s licensing business, QTL, and the vast majority of its patent portfolio. Qualcomm Technologies, Inc., a wholly-owned subsidiary of Qualcomm Incorporated, operates, along with its subsidiaries, substantially all of Qualcomm’s engineering, research and development functions, and substantially all of its product and services businesses, including its semiconductor business. ©2013-2015 Qualcomm Technologies, Inc. All Rights Reserved.

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