1. OBSS Preamble Detection
May 2015
OBSS Preamble Detection
Evaluation
Date:
Authors:
Name
Affiliations
Address
Phone
Suhwook Kim
LG Electronics
19, Yangjea-daero 11gil, Seocho-gu, Seoul , Korea
Wookbong Lee
Hyeyoung Choi
Jeongki Kim
Kiseon Ryu
HanGyu Cho
Suhwook Kim, LG Electronics

2. May 2015
Abstract
This submission provides evaluation of OBSS preamble detection using PHY/MAC integrated simulator
We use preamble decoding procedure which is agreed within integrated simulator member
We consider frame type (Data/ACK) and link direction (DL/UL) to analyze OBSS preamble detection probability
Suhwook Kim, LG Electronics

3. Submissions on Preamble Detection
May 2015
Submissions on Preamble Detection
r1[1], r0[2]
Evaluate OBSS preamble detection using MAC simulator
OBSS preamble error probability is above 80%
Suhwook Kim, LG Electronics

4. Preamble Error Model May 2015 Signal Detect: At the start of preamble,
Preamble Error Detect
Preamble
PPDU
Signal Detect: At the start of preamble,
If the signal strength is above -82 dBm, receiver can start to detect the PPDU. [1]
The receiver should be in IDLE status to detect the preamble.
If the receiver is sending/receiving a frame or processing in inter-frame (SIFS), it cannot detect any preamble even though the signal strength is above -82 dBm
Preamble Error Detect: At the end of preamble,
In 1420r1, if minimum SINR ≤ 0 dB in preamble duration, then the preamble has errors. Otherwise, the preamble is correct. [1]
But in this submission, we use SINR-PER curve which is addressed from Box 0 calibration with channel model defined in SS document (980r10)
Preamble is modeled as 24 bits/symbol (BPSK 1/2) [3]
Preamble of Data frame: L-Part (5 symbols) + VHT-Part (5 symbols)
Preamble of Control frame: L-Part (5 symbols)
Suhwook Kim, LG Electronics

5. May 2015
Preamble Error Model
The receiver will be locked by the first-arrived packet, and later-arrived packets are considered as interference [3]
If preamble passes, the receiver continues to receive the rest part of the packet [3]
If successfully decoding of a MAC frame, defer for NAV;
Otherwise, set CCA to busy for the entire PPDU
If preamble fails, the receiver terminates current reception [3]
The entire PPDU fails
The receiver is unlocked again and then CCA-ED threshold is used to determine if the medium is busy
In this submission, CCA-ED=-62 dBm
Suhwook Kim, LG Electronics

6. Simulation Setup [2] May 2015 Simulator Type MAC simulator (in 367r0)
PHY/MAC Integrated simulator
Tx Power (AP/STA)
20/15dBm
Antenna Gain (AP/STA)
0/-2 dBi
Traffic Model
UL only full buffer (in 367r0)
DL only, UL only, mixed DL&UL full buffer
BSS Bandwidth
80MHz
Noise Figure
Noise Floor
-101dBm per 20MHz
Rate Control Algorithm
single MCS chosen per link to maximize goodput
(in 367r0)
Open Loop Link Adaption [4]
MSDU size (bytes)
1476
TXOP size
4 ms
Max Retx 10
Simulation Time (sec)
PER Curve
AWGN(in 367r0)
addressed from Box 0 calibration
Suhwook Kim, LG Electronics

7. Simulation Setup: modified Scenario 1 [2]
May 2015
Simulation Setup: modified Scenario 1 [2]
Same as r0[2]
3 channels
Chosen to maximize distance between two apartments one 1 channel.
5 STAs per AP
1 antenna per AP & STA
Suhwook Kim, LG Electronics

8. Throughput May 2015 5% 50% 90% Mean DL only 0.67 Mbps 10.15 Mbps
UL only
3.24 Mbps
7.69 Mbps
27.33 Mbps
11.80 Mbps
DL (in DL&UL)
1.08 Mbps
2.59 Mbps
4.65 Mbps
2.82 Mbps
UL (in DL&UL)
2.36 Mbps
5.74 Mbps
14.13 Mbps
7.65 Mbps
Suhwook Kim, LG Electronics

9. May 2015
Preamble detection
Nt: number of total OBSS preambles which has signal strength above -82 dBm
Nd: number of detected OBSS preambles
signal strength is over -82 dBm & arrived at IDLE status
Ns: number of success decoded OBSS preambles
Suhwook Kim, LG Electronics

10. OBSS Preamble detection
May 2015
OBSS Preamble detection
Nd / Nt
Ns / Nd
Ns / Nt
DL only
DL Data
90.51%
46.17%
41.79%
UL ACK
92.50%
71.73%
66.35%
UL only
UL Data
63.07%
63.08%
39.78%
DL ACK
65.35%
99.14%
64.79%
DL & UL
61.09%
27.11%
16.56%
63.42%
51.83%
32.87%
57.93%
50.40%
29.20%
63.28%
99.21%
62.78%
Suhwook Kim, LG Electronics

11. OBSS Preamble detection per BSS
May 2015
OBSS Preamble detection per BSS
Suhwook Kim, LG Electronics

12. RSSI of detected OBSS preambles
May 2015
RSSI of detected OBSS preambles
Data Frame
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

13. RSSI of detected OBSS preambles
May 2015
RSSI of detected OBSS preambles
ACK Frame
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

14. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
Data Frame – Success
Maximum SINR of BPSK ½ in MMIB = 9.1 dB
Preamble sent by AP
Preamble sent by STA
Suhwook Kim, LG Electronics

15. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
Data Frame – Failed
Preamble sent by AP
Preamble sent by STA
Suhwook Kim, LG Electronics

16. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
ACK Frame – Success
Maximum SINR of BPSK ½ in MMIB = 9.1 dB
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

17. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
ACK Frame – Failed
Preamble sent by AP
Preamble sent by STA
Suhwook Kim, LG Electronics

18. Simulation Setup: Scenario 3
May 2015
Simulation Setup: Scenario 3
1 channel
19 APs operate in one same channel
30 STAs per AP
1 antenna per AP & STA
ICD = 30 meter 2 1 3 4 5 6 16 15 9 10 7 14 11 12 17 8 18 13
Suhwook Kim, LG Electronics

19. Throughput May 2015 5% 50% 90% Mean DL only 0.0 Mbps 0.50 Mbps
UL only
0.75 Mbps
2.32 Mbps
1.02 Mbps
DL (in DL&UL)
0.32 Mbps
0.08 Mbps
UL (in DL&UL)
0.73 Mbps
2.20 Mbps
0.98 Mbps
Suhwook Kim, LG Electronics

20. OBSS Preamble detection
May 2015
OBSS Preamble detection
Nd / Nt
Ns / Nd
Ns / Nt
DL only
DL Data
93.22%
31.49%
29.35%
UL ACK
97.53%
52.41%
51.11%
UL only
UL Data
73.24%
35.53%
26.02%
DL ACK
84.28%
99.05%
83.48%
DL & UL
78.84%
15.31%
12.07%
83.62%
17.85%
14.92%
72.65%
34.47%
25.04%
84.23%
99.01%
83.39%
Suhwook Kim, LG Electronics

21. OBSS Preamble detection per BSS
May 2015
OBSS Preamble detection per BSS
Suhwook Kim, LG Electronics

22. RSSI of detected OBSS preambles
May 2015
RSSI of detected OBSS preambles
Data Frame
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

23. RSSI of detected OBSS preambles
May 2015
RSSI of detected OBSS preambles
ACK Frame
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

24. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
Data Frame – Success
Maximum SINR of BPSK ½ in MMIB = 9.1 dB
Preamble sent by AP
Preamble sent by STA
Suhwook Kim, LG Electronics

25. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
Data Frame – Failed
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

26. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
ACK Frame – Success
Maximum SINR of BPSK ½ in MMIB = 9.1 dB
Preamble sent by STA
Preamble sent by AP
Suhwook Kim, LG Electronics

27. Effective SINR of detected OBSS preambles
May 2015
Effective SINR of detected OBSS preambles
ACK Frame – Failed
Preamble sent by AP
Preamble sent by STA
Suhwook Kim, LG Electronics

28. May 2015
Conclusion
In this submission, we evaluate OBSS preamble detection using PHY/MAC integrated simulator
We ran the simulations in modified residential scenario and indoor small BSS scenario
We observed following trends
Preamble error prob. of Data frame is HIGHER than ACK frame
Preamble error prob. of DL Data frame is HIGHER than UL Data frame
On the other hand, preamble error prob. of DL ACK frame is LOWER than UL ACK frame
Preamble error prob. is generally higher in mixed DL&UL traffic model
Preamble of DL ACK is almost decoded successfully (~99%)
Suhwook Kim, LG Electronics

29. May 2015
Reference
[1] 11-14/1420r1 The Impact of Preamble Error on MAC System Performance
[2] 11-15/0367r0 OBSS Preamble Detection
[3] 11-14/1523r5 Offline Discussion Minutes of SLS Calibration
[4] 11-14/620r0 link adaptation for PHY SLS calibration
Suhwook Kim, LG Electronics