1. OFDMA performance in 11ax
September 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
September 2016
Introduction
In contributions [1] – [9], we have addressed OFDMA performance based on PHY/MAC-integrated simulation
DL only, UL only
DL and UL mixed
Single BSS, OBSS(Residential)
MU-RTS/CTS
Full buffer traffic, low rate traffic
TCP traffic
The goal of this contribution is to verify that the target of 11ax PAR is met
i.e. four times throughput enhancement
Suhwook Kim, LG Electronics
John Doe, Some Company

3. Main update in the simulation
Month Year
doc.: IEEE yy/xxxxr0
September 2016
Main update in the simulation
RU size in OFDMA
242-tone RU has been considered in previous simulations
26-tone RU is considered in this simulation to exploit power gain of OFDMA based on small RU
Simulation scenario
We consider outdoor scenario which is more proper to verify UL OFDMA gain due to large coverage and bad channel condition
Suhwook Kim, LG Electronics
John Doe, Some Company

4. Simulation Parameters
September 2016
Simulation Parameters
Simulator Type
PHY/MAC Integrated simulator
Tx Power (AP/STA)
30/15 dBm (SS4 default value)
Antenna Gain (AP/STA)
0/-2 dBi
RX sensitivity
-92 dBm
Traffic Model
UDP UL only, Full buffer
BSS Bandwidth
80MHz
OFDMA parameter
37 RUs (26 tones), Random scheduler (1 RU for 1 STA)
EDCA parameter
Default AC_BE
MSDU size (bytes)
1000
Feedback
GENIE
RTS/CTS
OFDMA: OFF, Legacy: ON
Max Retx 10
Symbol length
4 usec (legacy), 16usec (OFDMA)
Metrics
Throughput
Queue Size
MAC Queue: AP: 2000 * # of associated STA, STA: 2000
Suhwook Kim, LG Electronics

5. Simulation Setup for Single BSS
Month Year
doc.: IEEE yy/xxxxr0
September 2016
Simulation Setup for Single BSS
Topology description
Number of STA: 37
STA location
15, 25, 35, 45, 55 meters from AP
Distribution of STA’s location: Next slide
Channel model
UMi, NLoS only
15 m
25 m
35 m
45 m
55 m
Suhwook Kim, LG Electronics
John Doe, Some Company

6. Simulation Cases for Single BSS
September 2016
Simulation Cases for Single BSS
Case 1: All STAs (37 STAs) are co-located
Case 1 – 1 : All STAs at 55 meters
Case 1 – 2 : All STAs at 45 meters
Case 1 – 3 : All STAs at 35 meters
Case 1 – 4 : All STAs at 25 meters
Case 1 – 5 : All STAs at 15 meters
Case 2: 37 STAs are equally distributed at most
7 / 7 / 7 / 8 / 8 (55m / 45m / 35m / 25m / 15m)
Suhwook Kim, LG Electronics

7. Simulation Setting: Best MCS and BW
Month Year
doc.: IEEE yy/xxxxr0
September 2016
Simulation Setting: Best MCS and BW
In each distance, the best combination of MCS and transmission BW was selected for legacy system through the simulation  
In OFDMA, best MCS was selected at each distance with fixed BW of 80MHz
55 meter
45 meter
35 meter
25 meter
15 meter
Legacy
Best set
20 MHz, MCS 0
40 MHz, MCS 0
80 MHz, MCS 0
80 MHz, MCS 1
80 MHz, MCS 3
Data rate
6.5 Mbps
13.5 Mbps
29.3 Mbps
58.5 Mbps
117 Mbps
OFDMA
MCS 3
MCS 4
MCS 6
MCS 8
130.6 Mbps
195.9 Mbps
293.8 Mbps
391.8 Mbps
Suhwook Kim, LG Electronics
John Doe, Some Company

8. Simulation Result for Single BSS: Case 1
September 2016
Simulation Result for Single BSS: Case 1
All STAs (37 STAs) are co-located
Note
OFDMA gain increases with distance between STA and AP
For distances larger than 15 meters, OFDMA gain is larger than four times
Case 1-1
(All STAs
at 55m)
Case 1-2
at 45m)
Case 1-3
at 35m)
Case 1-4
at 25m)
Case 1-5
at 15m)
Legacy
4.52 Mbps
7.94 Mbps
20.06 Mbps
48.33 Mbps
89.56 Mbps
OFDMA
69.68 Mbps
88.57 Mbps
Mbps
Mbps
Mbps
OFDMA gain
15.4
11.2
6.9
4.2
3.1
Suhwook Kim, LG Electronics

9. Simulation Result for Single BSS: Case 2
September 2016
Simulation Result for Single BSS: Case 2
37 STAs are equally distributed at most
Note
The gain of OFDMA is still large, but smaller than in case 1
It is because near STAs get more TXOP and dominantly affect the overall performance
55 meter
45 meter
35 meter
25 meter
15 meter
Number of STA 7 8
Legacy
SUM
56.62 Mbps
a STA
0.05
0.11
0.36
1.50
5.12
OFDMA
Mbps
1.40
1.76
3.63
5.30
7.50
OFDMA gain
2.7
Suhwook Kim, LG Electronics

10. Simulation Setup for OBSS
Month Year
doc.: IEEE yy/xxxxr0
September 2016
Simulation Setup for OBSS
Topology description
Number of STA per BSS: 37
Distance between AP: 130 meters (same distance with SS4 Outdoor Large BSS)
STA location: 15, 25, 35, 45, 55 meters from each home AP
Channel model: UMi, NLoS only
MCS and BW setting: Same as the single BSS case (as shown in slide 7)
55 m
55 m
130 m
Suhwook Kim, LG Electronics
John Doe, Some Company

11. Simulation Cases for OBSS
September 2016
Simulation Cases for OBSS
Case 3: All STAs (37 STAs per BSS) are co-located per BSS
Case 3 – 1 : All STAs at 55 meters from each home AP
Case 3 – 2 : All STAs at 45 meters from each home AP
Case 3 – 3 : All STAs at 35 meters from each home AP
Case 3 – 4 : All STAs at 25 meters from each home AP
Case 3 – 5 : All STAs at 15 meters from each home AP
Case 4: All STAs (37 STAs per BSS) are equally distributed at most
Each BSS uses the setting of Case 2 in Single BSS
7 / 7 / 7 / 8 / 8 (55m / 45m / 35m / 25m / 15m)
Suhwook Kim, LG Electronics

12. Simulation Result for OBSS: Case 3
September 2016
Simulation Result for OBSS: Case 3
Note
OBSS shows the similar trend as single BSS case
OFDMA gain increases with distance between STA and AP
For distances larger than 15 meters, OFDMA gain is larger than four times in single BSS and OBSS
Case 3-1
(All STAs
at 55m)
Case 3-2
at 45m)
Case 3-3
at 35m)
Case 3-4
at 25m)
Case 3-5
at 15m)
Legacy
3.0 Mbps
6.8 Mbps
17.4 Mbps
36.5 Mbps
72.8 Mbps
OFDMA
33.6 Mbps
46.1 Mbps
102.3 Mbps
166.1 Mbps
259.4 Mbps
OFDMA gain
11.2
6.8
5.9
4.6
3.6
Suhwook Kim, LG Electronics

13. Simulation Result for OBSS: Case 4
September 2016
Simulation Result for OBSS: Case 4
55 meter
45 meter
35 meter
25 meter
15 meter
Number of STA 7 8
Legacy
SUM
53.48 Mbps
a STA
0.03
0.09
0.29
1.38
4.94
OFDMA
Mbps
0.65
1.04
2.37
4.77
7.09
OFDMA gain
2.3
Note
OBSS shows the similar trend as single BSS case
Regarding far STAs (e.g. 55m), gains of OFDMA is quite large (larger than 20 times)
Regarding near STAs (e.g. 15m), gains of OFDMA decreases (around 50%)
Suhwook Kim, LG Electronics

14. September 2016
Conclusion
We verified that OFDMA can provide four times throughput enhancement in outdoor environment
Far STAs provide gains of more than four times due to power gain in UL by using a smaller RU (e.g. 26-tone RU)
But, near STAs provide smaller gains than four times
More gain in OFDMA can be obtained e.g., by adopting a better scheduler than a random scheduler
Suhwook Kim, LG Electronics

15. September 2016
Reference
[1] ~ [9] 11-15/1095r0 ~ r9
[10] 11-14/0980r14 Simulation Scenarios
Suhwook Kim, LG Electronics