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 [email protected]
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
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