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Latency investigation

-including Speedtest.net

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Agenda

Objective

Test Cases

Performance Results & Analysis Prescheduling

Initial UL Buffer Size

SR Periodicity

Moving Forward

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Objective

Ericsson has been asked by customer to

investigate the latency time by parameter

changes due to observing poor latency via

Speedtest.net

Areas of testing are:

Prescheduling

Initial UL buffer size

SR periodicity

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Test cases

The below test cases were executed while recording TEMs, using a Samsung Galaxy S3LTE I9305 UE

Parameter Value Comments

TCBaseline Prescheduling Disabled default

SR Prediocity 10 default

Initial Buffer Size 86 default

TC1 Prescheduling Enabled

Initial Buffer Size 86 default

TC2 Prescheduling Enabled

Initial Buffer Size 300

TC3 Prescheduling Disabled default

SR Pediocity 10 default

Initial Buffer Size 300

TC4 Prescheduling Disabled default

SR Prediocity 5

Initial Buffer Size 86 default

Test are performed on good LTE radio

condition where:

RSRP > -80dBm

RSRQ > -7dB

SINR < 20dB

Basic 32B, 1000B, idle to connected 32B

Optional Speedtest

Connected Mode 100 ping samples 1 second between pings

Idle Mode 20 samples Reduce inactivity timer to 10 seconds for purpose for testing

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Comparison

Prescheduling ON and Disabled

Baseline vs TC1

Initial UL buffer size Default vs 300B Baseline vs TC3, TC1 & TC2

SR periodicity 10 ms vs 5 ms

Baseline vs TC4

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Performance Results

Summary- prescheduler = Disabled

- prescheduler = Enabled

- prescheduler = Enabled, initial buffer size = 300

- prescheduer = Disabled, initial buffer size = 300

- prescheduler = Disabled, SR periodicity = 5

Below is the Average Results of performance

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Performance Results

Summary

32B Connected Delta 1000BConnected

Delta

Idle to

Connected

(32B)

Delta SpeedTest Delta

TCBaseline (TCB)

Prescheduling = Disabled (Default)

SR Periodicity = 10 (Default)

Initial Buffer Size = 86 (Default)

29.53 38.07 248.89 36.50

TC1

Prescheduling = Enabled

SR Periodicity = 10 (Default)

Initial Buffer Size = 86 (Default)

15.6013.93

(47.18%)22.94

15.13

(39.74%)222.33

26.56

(10.67%)23.20

13.30

(36.44%)

TC2

Prescheduling = Enabled

SR Periodicity = 10 (Default)

InitialBufferSize = 300

15.6113.92

(47.13%)18.98

19.09

(50.15%)225.44

23.45

(9.42%)18.10

18.40

(50.41%)

TC3

Prescheduling = Disabled (Default

SR Periodicity = 10 (Default)

Initial Buffer Size = 300

28.131.40

(4.72%)37.46

0.61

(1.61%)248.28

0.61

(0.25%)28.70

7.80

(21.37%)

TC4

Prescheduling = Disabled (Default)

SR Periodicity = 5

Initial Buffer Size = 86 (Default)

26.473.06

(10.36%)34.06

4.01

(10.54%)241.89

7.00

(2.81%)33.00

3.50

(9.59%)

Parameter

Average Latency (ms)

Delta comparison is based on the individual Test Cases (TC) vs Baseline (TCB).

Highest latency improvements observed with preschedulingON (TC1 & TC2).

Higher initial UL buffer sizeimproves latency for bigger ping sizes, where whole data can be

sent without data fragmentation.

Average of 3ms latency improvement is observed with a lower SR periodicitysetting.

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PRescheduling

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What is causing delays?

Current behaviour for small ping