September 2006
doc.: IEEE 802.11-06/1482r0
CA Document Update
Date: 2006-9-19
Authors:
Name
Company
Address
Eldad Perahia Intel
Phone
email
eldad.perahia
@intel.com
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Submission
Slide 1
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Abstract
• Review update to the CA document in 06/338r4
Submission
Slide 2
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Comment Summary
• 7846, 7855: Analysis treats BT like wideband interferer. Run
simulation with a PSD representative of BT
• 7846, 7855: 11n can operate in both 20 and 40MHz, run sims in
both 20 and 40 MHz
• 7853, 7855: Analysis of collision with BT packet causes complete
11n packet failure. Consider model in which collision only
corrupts a portion of the aggregate
• 7854: Add probability of collision plots, not just throughput
• 7870: No information provided for 802.15.4, please provide
Submission
Slide 3
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
BT interferer waveform simulated in PHY
sim
Submission
Slide 4
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
PER vs. SIR for 20MHz, channel model B
with P802.15.1 interference
SNR = 40dB
1
MCS
BW
(MH
z)
Data
Rate
Mb/s
Required
SNR (dB)
@
PER=1%
0
20
6.5
12
7
20
65
31
15
20
130
35.5
PER
0.1
MCS 0; 1x2
MCS 7; 1x2
MCS 15; 2x3
0.01
0.001
0
5
10
15
20
SIR (dB)
25
30
35
40
More degradation to interference than to noise
•Interference power concentrated in just a few tones
•Channel estimate and Decoder metrics are adversely effected by interference with basic
MMSE receiver
Submission
Slide 5
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
11n Link
• Link budget modified to
separate received SNR and
minimum allowable C/I
• Process to calculate
separation between STA and
interferer
– Set desired AP – STA
separation, which determines
the Received SNR
– Run PER vs SIR curve at
Received SNR
– Calculate Interferer – STA
separation based on minimum
allowable C/I
Submission
Slide 6
Tx Power
Tx antenna gain
pathloss
frequency
distance
breakpoint
shadow fading before
breakpoint
shadow fading after
breakpoint
free space
total loss
dBm
dBi
17
2
GHz
m
m
2.4
20
5
dB
dB
4
54.0
79.1
Rx antenna gain
RSSI
Noise Power
NF
BW
total
Received SNR
dBi
dBm
2
-58.1
dB
MHz
dBm
dB
6
20
-95.0
36.9
3
minimum allowable C/I
Allowable Receive
Interference power
dBm
-79.2
Interferer
Tx Power
Tx antenna gain
Pathloss
separation from STA
dBm
dBi
dB
m
0
2
83.2
26.2
21.1
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
40 MHz
Submission
Slide 7
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
PER curves for 40MHz, channel model B
1
0.1
PER
MCS 32; 1x2
MCS 0; 1x2
MCS 7; 1x2
MCS 15; 2x3
0.01
0.001
-5
Submission
0
5
10
15
20
SNR (dB)
Slide 8
25
30
35
40
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
PER vs. SIR for 40MHz, channel model B
with P802.15.1 interference
SNR = 40dB
1
0.1
PER
MCS 32; 1x2
MCS 0; 1x2
MCS 7; 1x2
MCS 15; 2x3
0.01
0.001
0
5
10
15
20
SIR (dB)
25
30
35
40
20 MHz and 40 MHz p802.11n receivers experience similar degradation
from a P802.15.1 interferer
Submission
Slide 9
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
40MHz spectral plot
40 MHz HT ( HT-LTF and HT-Data)
25
20
15
10
Power (dB)
5
0
-5
-10
-15
-20
-25
-30
-20
Submission
-15
-10
-5
0
Frequency (MHz)
Slide 10
5
10
15
20
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Partial Packet Failure
Submission
Slide 11
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Partial Packet Failure
• With A-MSDU aggregation, the entire aggregate is protected by a
single FCS
– Therefore bit errors anywhere in the aggregate will cause all subframes to
be lost and require retransmission.
– As such, A-MSDU aggregation follows the previously provided
derivation
• With A-MPDU aggregation, each MPDU contains its own FCS. In
addition, each MPDU is preceded by a delimiter. Therefore
portions of the transmission can be corrupted without loosing all
MPDUs
– However, if the PHY preamble and header are corrupted by a collision
with a P802.15.1 packet, the entire aggregate will still be lost
– New analysis provided such that only MPDUs which collided with
P802.15.1 packets were considered lost. If a P802.15.1 packet collided
with the PHY preamble, the entire aggregate was considered lost
Submission
Slide 12
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on p802.11n throughput for 130Mb/s,
20MHz mode with A-MPDU model
PHY Data Rate = 130.0 Mb/s; BW = 20 MHz; sub-packet length = 1500B
120
• Performance with A-MPDU
model substantially improved
over A-MSDU model with
high BT occupancy
11n Throughput (Mb/s)
100
80
BT Occup = 0%
10%
50%
100%
60
40
20
0
Submission
0
5
Slide 13
10
15
20
25
30
Aggregate Packet Length(kBytes)
35
40
Eldad Perahia (Intel)
45
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on p802.11n throughput for 270Mb/s,
40MHz mode with A-MPDU model
PHY Data Rate = 270 Mb/s; BW = 40 MHz; sub-packet length = 1500B
250
11n Throughput (Mb/s)
200
150
100
BT Occup = 0%
10%
50%
100%
50
0
Submission
0
10
20
30
40
50
60
Aggregate Packet Length(kBytes)
Slide 14
70
80
90
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
p802.11n throughput with A-MPDU
aggregation
C/N = 40dB
110
100
90
11n Throughput (Mbps)
• In terms of throughput vs
STA-Interferer separation, AMPDU is a little better than
A-MSDU at smaller
separation, but results
converge at larger separations
80
MCS 0, 1x2
MCS 7, 1x2
MCS 15, 2x3
70
60
50
40
30
20
10
0
0
10
20
30
40
50
60
70
80
90 100 110 120
STA - Interferer Separation (m)
Submission
Slide 15
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Probability of Collision Plots
Submission
Slide 16
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on probability of collision for 130Mb/s,
20MHz mode
PHY Data Rate = 130.0 Mb/s; BW = 20 MHz
0.8
0.7
Probability of Collision
0.6
BT occup = 0%
10%
50%
100%
0.5
0.4
0.3
0.2
0.1
0
Submission
0
5
10
15
20
25
30
Aggregate Packet Length (kBytes)
Slide 17
35
40
45
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on probability of collision for 6.5Mb/s,
20MHz mode
PHY Data Rate = 6.5 Mb/s; BW = 20 MHz
0.8
0.7
Probability of Collision
0.6
BT occup = 0%
10%
50%
100%
0.5
0.4
0.3
0.2
0.1
0
Submission
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
Aggregate Packet Length (kBytes)
Slide 18
1.8
1.9
2
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on probability of collision for 270Mb/s,
40MHz mode
PHY Data Rate = 270.0 Mb/s; BW = 40 MHz
1
0.9
Probability of Collision
0.8
BT occup = 0%
10%
50%
100%
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Submission
0
10
20
30
40
50
60
Aggregate Packet Length (kBytes)
Slide 19
70
80
90
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Impact of aggregate packet length and P802.15.1
utilization on probability of collision for
13.5Mb/s, 40MHz mode
PHY Data Rate = 13.5 Mb/s; BW = 40 MHz
1
0.9
Probability of Collision
0.8
BT occup = 0%
10%
50%
100%
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Submission
1
1.5
2
2.5
3
Aggregate Packet Length (kBytes)
Slide 20
3.5
4
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
P802.15.4 Interferer
Submission
Slide 21
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Pertinent Parameters
•
•
•
The scope and purpose of P802.15.4 is to provide specification for low data rate
connectivity and ultra-low power consumption for use in the personal operating
space of 10 m. The applications range from interactive toys to sensor and
automation
Low Data Rate: 250 kbps
Tx Power [P802.15.4, Annex E.2.5]
–
–
•
Low Duty Cycle [ P802.15.4, Annex E.2.4]
–
•
1%
Dynamic Channel Selection [ P802.15.4, Annex E.2.6]
–
–
•
ranging from -3 dBm to 10 dBm
0 dBm typical
Channel center frequency Fc = 2405+(k - 11)*5 in MHz, for k = 11, 12,…, 26
Channels 15, 20, 25, and 26 do not overlap with 802.11, 2.4 GHz, channels 1, 6, and 11 with 20
MHz channel
Average Packet Length [P802.15.4, Annex E.3.1.9]
–
–
Submission
22 bytes
with overhead, typical P802.15.4 packet length is ~900 μsec, on the order of a p802.11n TXOP
Slide 22
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
Channel Selection
40 MHz
20 MHz
2462
2437
2412
2400
MHz
2483.5
MHz
a) Example p802.11n channel selection
2 MHz
b) P802.15.4 channel selection (2400 MHz PHY)
Slide 23
2480
2475
2470
2465
2460
2455
2450
2445
2440
2435
2430
2425
2420
2415
Submission
2410
2405
2400
MHz
2483.5
MHz
Eldad Perahia (Intel)
September 2006
doc.: IEEE 802.11-06/1482r0
PER vs. SIR for 20 MHz, channel model B
with P802.15.4 interference
• P802.15.4 waveform
incorporated into the
simulation as
interference source
• Curves run for various
channel offsets
MCS 0; 1x2; offset=-2 MHz
MCS 0; 1x2; offset=3 MHz
MCS 0; 1x2; offset=-7 MHz
MCS 0; 1x2; offset=8 MHz
MCS 7; 1x2; offset=-2 MHz
MCS 7; 1x2; offset=3 MHz
MCS 7; 1x2; offset=-7 MHz
MCS 7; 1x2; offset=8 MHz
MCS 15; 2x3; offset=-2 MHz
MCS 15; 2x3; offset=3 MHz
MCS 15; 2x3; offset=-7 MHz
MCS 15; 2x3; offset=8 MHz
SNR = 40dB
1
PER
0.1
0.01
0.001
0
5
10
15
20
25
30
35
40
45
SIR (dB)
Submission
Slide 24
Eldad Perahia (Intel)
50
September 2006
doc.: IEEE 802.11-06/1482r0
PER vs. SIR for 40 MHz, channel model B
with P802.15.4 interference
SNR = 40dB
1
MCS 15
PER
0.1
0.01
MCS 0
MCS 32
MCS 7
0.001
-5
Submission
0
5 10 15 20 25 30 35 40 45 50
SIR (dB)
Slide 25
MCS 32; 1x2; offset=-2 MHz
MCS 32; 1x2; offset=3 MHz
MCS 32; 1x2; offset=-7 MHz
MCS 32; 1x2; offset=8 MHz
MCS 32; 1x2; offset=-12 MHz
MCS 32; 1x2; offset=13 MHz
MCS 32; 1x2; offset=-17 MHz
MCS 32; 1x2; offset=18 MHz
MCS 0; 1x2; offset=-2 MHz
MCS 0; 1x2; offset=3 MHz
MCS 0; 1x2; offset=-7 MHz
MCS 0; 1x2; offset=8 MHz
MCS 0; 1x2; offset=-12 MHz
MCS 0; 1x2; offset=13 MHz
MCS 0; 1x2; offset=-17 MHz
MCS 0; 1x2; offset=18 MHz
MCS 7; 1x2; offset=-2 MHz
MCS 7; 1x2; offset=3 MHz
MCS 7; 1x2; offset=-7 MHz
MCS 7; 1x2; offset=8 MHz
MCS 7; 1x2; offset=-12 MHz
MCS 7; 1x2; offset=13 MHz
MCS 7; 1x2; offset=-17 MHz
MCS 7; 1x2; offset=18 MHz
MCS 15; 2x3; offset=-2 MHz
MCS 15; 2x3; offset=3 MHz
MCS 15; 2x3; offset=-7 MHz
MCS 15; 2x3; offset=8 MHz
MCS 15; 2x3; offset=-12 MHz
MCS 15; 2x3; offset=13 MHz
MCS 15; 2x3; offset=-17 MHz
MCS 15; 2x3; offset=18 MHz
Eldad Perahia (Intel)