1. OFDMA performance in 11ax
January 2016
OFDMA performance in 11ax
Date:
Authors:
Name
Affiliations
Address
Phone
Suhwook Kim
LG Electronics
19, Yangjea-daero 11gil, Seocho-gu, Seoul , Korea
Hyunhee Park
Jeongki Kim
Kiseon Ryu
HanGyu Cho
Suhwook Kim, LG Electronics

2. Month Year
doc.: IEEE yy/xxxxr0
January 2016
Introduction
From September meeting, we have addressed OFDMA performance using PHY/MAC integrated simulator
OFDMA shows better performance in throughput and latency in DL & UL mixed traffic
This presentation provides update on it
Suhwook Kim, LG Electronics
John Doe, Some Company

3. Update on Simulation MU-RTS/CTS CCA in UL-OFDMA
January 2016
Update on Simulation
MU-RTS/CTS
We evaluate MU-RTS/CTS on OFDMA
CCA in UL-OFDMA
STAs perform CCA after Trigger frame reception
Suhwook Kim, LG Electronics

4. Simulation Setup: Scheduler
January 2016
Simulation Setup: Scheduler
Scheduling resource
Maximum allocation per one station is 1 RU
1 RU: 242-tone (total 4 RUs in 80 MHz)
Scheduling policy
Random: AP selects STAs randomly
In DL case,
primary destination is fixed (Head of AP’s queue)
frame length is determined by A-MPDU length to primary destination (legacy spec rule)
Suhwook Kim, LG Electronics

5. CCA in UL-OFDMA CCA in UL-OFDMA
January 2016
CCA in UL-OFDMA
CCA in UL-OFDMA
STAs perform CCA after Trigger frame reception
Suhwook Kim, LG Electronics

6. MU-RTS/CTS in DL-OFDMA
January 2016
MU-RTS/CTS in DL-OFDMA
MU-RTS/CTS
Suhwook Kim, LG Electronics

7. MU-RTS/CTS in DL-OFDMA
January 2016
MU-RTS/CTS in DL-OFDMA
Detail operation
We evaluate simple MU-RTS/CTS scheme because of simulator issue
Resource for RTS/CTS is aligned with Data/ACK transmission
Only one resource unit can be allocated for RTS/CTS/DATA/ACK
Preamble detection thresholds are -82 dBm for primary channel and -72 dBm for secondary channels
STAs perform CCA after RTS frame reception
If a channel which is allocated for data is sensed as busy, the STA will not transmit CTS frame
Suhwook Kim, LG Electronics

8. Simulation Setup: Parameters
January 2016
Simulation Setup: Parameters
Simulator Type
PHY/MAC Integrated simulator
Tx Power (AP/STA)
20/15 dBm (Topology 3)
Antenna Gain (AP/STA)
0/-2 dBi
Traffic Model
DL and UL mixed (CBR)
BSS Bandwidth
80MHz
Noise Figure
Noise Floor
-101dBm per 20MHz
Rate Control Algorithm
Open Loop Link Adaption [3]
MSDU size (bytes)
1472
Feedback
GENIE
Max Retx 10
Symbol length
4 usec (legacy), 16usec (OFDMA)
Metrics
Throughput
Queue Size
AP: 1000 * # of associated STA, STA: 1000
Suhwook Kim, LG Electronics

9. Topology Topology description Simulation setting
January 2016
Topology
Topology description
20 APs (Fixed location: center of room)
4 or 10 or 20 STAs per one AP (Random location)
Primary/secondary channels of every AP are same
Simulation setting
Open Loop Link Adaption [3]
Channelization: Fixed channelization
Trigger frame is generated every 10 msec period and trigger frame has priority over data frame
CH1
CH2
CH3
Suhwook Kim, LG Electronics

10. Simulation cases Case 1: Throughput vs. # of STAs (DL/UL 4 Mbps)
January 2016
Simulation cases
Case 1: Throughput vs. # of STAs (DL/UL 4 Mbps)
4 STAs
10 STAs
20 STAs
Case 2: Throughput vs. Traffic load (4 STAs)
DL/UL 4 Mbps
DL/UL 50 Mbps
Suhwook Kim, LG Electronics

11. Simulation Result – Case 1
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 1
OFDMA
Suhwook Kim, LG Electronics
John Doe, Some Company

12. Simulation Result – Case 1
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 1
Legacy
Suhwook Kim, LG Electronics
John Doe, Some Company

13. Simulation Result – Case 1
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 1
Legacy vs. OFDMA
Observation
RTS/CTS is more powerful in many STAs case
Throughput gain of RTS/CTS is more larger in legacy case
Nevertheless, OFDMA shows better throughput in dense cases
Throughput
[Mbps]　
4 STAs
10 STAs
20 STAs
RTS
no RTS
Legacy DL
16.00
40.02
7.95
55.59
2.06 UL
40.01
27.30
71.76
28.82
SUM
32.00
80.03
35.25
127.35
30.88
OFDMA
15.65
15.78
37.68
38.62
67.28
58.71
15.91
39.80
79.21
77.81
31.29
31.69
77.48
78.41
146.50
136.52
Suhwook Kim, LG Electronics
John Doe, Some Company

14. Simulation Result – Case 2
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 2
OFDMA
Suhwook Kim, LG Electronics
John Doe, Some Company

15. Simulation Result – Case 2
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 2
Legacy
Suhwook Kim, LG Electronics
John Doe, Some Company

16. Simulation Result – Case 2
Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result – Case 2
Legacy vs. OFDMA
Observation
Throughput gain of RTS/CTS is more larger in legacy case
In 4-STA-OFDMA case, throughput gain of RTS/CTS is limited even though traffic level increases
Nevertheless, OFDMA shows better throughput in most cases
Throughput
[Mbps]
4 Mbps
50 Mbps
RTS
no RTS
Legacy DL
16.00
44.17
7.95 UL
129.01
27.3
SUM
32.00
173.19
35.25
OFDMA
15.65
15.78
82.63
79.39
15.91
128.13
129.87
31.29
31.69
210.76
209.26
Suhwook Kim, LG Electronics
John Doe, Some Company

17. Next Step Following items will be added to OFDMA simulation
January 2016
Next Step
Following items will be added to OFDMA simulation
Advanced MU-RTS/CTS
Feedback modeling
Sophisticated schedulers
Different scenarios/traffic model
Suhwook Kim, LG Electronics

18. January 2016
Conclusion
We addressed OFDMA performance when we use simple MU-RTS/CTS and CCA after trigger frame
RTS/CTS is more powerful in many STAs case and legacy cases
Nevertheless, OFDMA shows better throughput
Suhwook Kim, LG Electronics

19. Reference [1] 11-15/0132r7 Spec Framework
January 2016
Reference
[1] 11-15/0132r7 Spec Framework
[2] 11-14/0980r14 Simulation Scenarios
[3] 11-14/620r0 link adaptation for PHY SLS calibration
[4] 11-14/0571r10 11ax Evaluation Methodology
Suhwook Kim, LG Electronics

20. January 2016
Backup Slide - PER
Suhwook Kim, LG Electronics

21. Simulation Result Legacy vs. OFDMA January 2016 Month Year
doc.: IEEE yy/xxxxr0
January 2016
Simulation Result
Legacy vs. OFDMA
PER
[%]　
4 STAs
10 STAs
20 STAs
RTS
no RTS
Legacy DL
0.5
9.1
0.6
12.7
0.7
17.4 UL
0.0
20.7
40.7
63.2
OFDMA
7.2
12.8
13.5
16.7
16.9
17.1
3.0
3.5
4.9
5.3
6.4
6.6
PER
[%]　
4 Mbps
50 Mbps
RTS
no RTS
Legacy DL
0.5
9.1
27.3 UL
0.0
20.7
49.4
OFDMA
7.2
12.8
11.5
12.5
3.0
3.5
4.7
Suhwook Kim, LG Electronics
John Doe, Some Company