doc.: IEEE 802.11-14/0045r1

Submission

Jan 2014

E-Education AnalysisHEW SG

Date: 2014-01

Authors:

Name Company Address Phone email Graham Smith DSP Group 1037 Suncast

Lane, Ste 112, El Dorado Hills, CA95762

916 358 8725 Graham.smith@dspg.com

Graham

Smith, DSP

Group

Slide 1

doc.: IEEE 802.11-14/0045r1

Submission

Background• This presentation looks at the E-Education HEW Use Case.

See also:• Use Case Dense Apartments 13/1487r2

– “Single” apartment complex 2.4 to 2.96 improvement in throughput per apartment (using DSC and Channel; Selection)

– “Double” apartment complex 3.3 to 4.12 improvement in throughput per apartment (using DSC and Channel; Selection)

• Airport Capacity 13/1489r4– Can be satisfied by existing technology

• E-Education 14/0045– Improvement of 2.28 in throughput per classroom using DSC

• Pico Cell 14/0048• Improvement of 7.58 in in capacity using DSC in cell cluster pattern (see 13/1290)• “Street” Pico cell can be satisfied with existing technology

• DSC is explained in 13/1012 and 13/1290

Jan 2014

Graham

Smith, DSP

Group

Slide 2

doc.: IEEE 802.11-14/0045r1

Submission

• To look at the prime HEW Use Cases and see what is theoretically possible using known techniques.

• Then to determine if there is a “gap” that can lead to a requirement for HEW.

Objective

Jan 2014

Graham

Smith, DSP

Group

Slide 3

doc.: IEEE 802.11-14/0045r1

Submission

July 2013

1e e-Education• Scenario Characteristics:

– Dense STAs (40~60 STAs) in one classroom with one AP– 20~30 classrooms in one typical school building (3~6 floors)– Thus, nearby 1,000 STAs with 20~30 APs within a building

space.

• Typical education applications:– Video streaming among teacher and students;– Teachers/Students demonstrate theirs desktop to others;– File transfer and sharing;– 4+ subgroup in one classroom with multicasting traffic for screen sharing or video;

Throughput assumption: longtime/stable throughput in one classroom >= 20 Mbps

• Challenges and Issues: – Fast Connection: Very long STAs registering time (1~5 minutes) delay the start of a class;– Interference Control and Delay Optimization:

• Annoying lag in screen sharing, video streaming and command response (sometimes it is longer than 20 seconds)

• Very low bandwidth for e-homework submission in the same period.

Slide 4 Laurent Cariou (Orange)

doc.: IEEE 802.11-14/0045r1

Submission

July 2013

1e e-Education

Pre-ConditionsWLAN is deployed in a each classroom of a campus in order to provide communication tools for e-Education.

Environment Dense STAs (40~60 STAs) in one classroom with one AP. 20~30 classrooms in one typical school building (3~6 floors).

Nearby 1,000 STAs with 20~30 APs within a building space.

ApplicationsVideo streaming among teacher and students;

Teachers/Students demonstrate theirs desktop to others;

File transfer and sharing;

4+ subgroup in one classroom with multicasting traffic for screen sharing or video;

Throughput assumption: longtime/stable throughput in one classroom >= 20 Mbps

Traffic ConditionsInterference between APs in different classrooms belonging to the same managed ESS due to high density deployment.

interference with peer-to-peer networks within each classroom.

Use Casee-Education starts in multiple classrooms simultaneously.Teacher/students demonstrated their desktop to others, video or screens are shared.

Slide 5 Laurent Cariou (Orange)

doc.: IEEE 802.11-14/0045r1

Submission

Classroom

Jan 2014

Graham

Smith, DSP

Group

Slide 6

AP

Say 30 x 30ft

40 desks

doc.: IEEE 802.11-14/0045r1

Submission

Channels

Jan 2014

Graham

Smith, DSP

Group

Slide 7

140

136

132

128

124

120

116

112

108

104

100

165

161

157

153

149

6460565248444036IEEE channel #

20 MHz

40 MHz

80 MHz

5170MHz

5330MHz

5490MHz

5710MHz

5735MHz

5835MHz

160 MHz

144

USA Eu Japan China Korea25 20MHz Channels 21 19 23 13 2112 40MHz Channels 10 9 10 6 10 6 80MHz Channels 4 4 5 3 5 2 160MHz Channels 1 2 2 1 2

Ref:Wikipedia

doc.: IEEE 802.11-14/0045r1

Submission

Building Complex example – one side

Jan 2014

Graham

Smith, DSP

Group

Slide 8

Classroom

-45dBm -42dBm

-42dBm -30dBm

Assumed 3dB wall loss10dB Floor loss

AP A1 B1 -47dBm C1 -57dBm D1 -78dBmA2 -47dBm B2 -57dBm C2 -70dBmA3 -60dBm B3 -68dBm C3 -77dBmA4 -70dBm

30ft

30ft10ft

6

CBA

5

4

3

2

1

USING DSC Limit -30dBm, Margin 20dB “Overlapping” Rooms with DSCAP set for -55dBm

Use of directivity on antennas could assist

doc.: IEEE 802.11-14/0045r1

Submission

Building Complex Example – Other side

Jan 2014

Graham

Smith, DSP

Group

Slide 9

-45dBm -42dBm

-42dBm -30dBm

30ft

10ft

8ft

-51dBm -58dBm -60dBm

-64dBm -65dBm -79dBm

-75dBm -76dBm

30ft

USING DSC Limit -30dBm, Margin 20dB AP set for -55dBm

“Overlapping” Rooms with DSC

Note: Without DSC blocked rooms doubles.

doc.: IEEE 802.11-14/0045r1

Submission

Channel Selection

Jan 2014

Graham

Smith, DSP

Group

Slide 10

As situation is controlled, AP channels can be presetExample is extreme for 36 classrooms, worse case layout

doc.: IEEE 802.11-14/0045r1

Submission

• Assuming 2SS for the STA, and using SU MIMO• With DSC 10 Channels (40MHz)• Without DSC 20 Channels (20MHz)• Signal strength within each class is >-45dBm hence can

use 256 QAM 5/6– 11ac PHY Rate for 40MHz, 2SS is 400Mbps (10 Channels)

• Max Throughput 344Mbps (131k agg)• Say 240Mbps throughput*

– 11ac PHY Rate for 20MHz, 2SS is 173Mbps (3/4 rate, 5/6 is excluded)

• Max Throughput 150Mbps (65k agg – 131k exceeds length)• Say 105Mbps throughput*

• Improvement is 2.28 Downlink could use MU-MIMO?

*Assuming EDCA Overhead.

11ac Rates

Jan 2014

Graham

Smith, DSP

Group

Slide 11

doc.: IEEE 802.11-14/0045r1

Submission

• Unclear what the Use Case requirement is.– 20 Mbps?

• Downlink would be multicast?

• With DSC ~240Mbps per class (6Mbps per pupil)• Without DSC ~ 105Mbps per class (2.6Mbps per pupil)

Not sure what the ‘gap’ is, but hopefully this quick analysis will help determine it.

What is Use Case Requirement?

Jan 2014

Graham

Smith, DSP

Group

Slide 12

doc.: IEEE 802.11-14/0045r1

Submission

• Isolation between classrooms could be improved by antenna directivity

• With 11ac SU-MIMO, DSC provides 240Mbps per classroom throughput

• Without DSC SU-MIMO provides ~105Mbps per classroom throughput

Improvement of x2.28 per classroom.• “Fast” connection – is this satisfied with 11ai?• Interference/OBSS greatly improved by DSC and also

by antenna positioning.

Discussion

Jan 2014

Graham

Smith, DSP

Group

Slide 13

doc.: IEEE 802.11-14/0045r1

Submission

• My personal opinion is that 11ac provides sufficient data throughput and efficiency and not easy to see any need for improvement.

• The basic need is for higher channel re-use so that the higher BWs can be used.

• Channel re-use can be improved with DSC but also by not using omni-directional antennas. – Corner antennas, such as used in cellular for example.– Easy to do if a ‘managed’ network.

Conclusions

Jan 2014

Graham

Smith, DSP

Group

Slide 14