doc.: IEEE 802.11-14/1443r0

Submission Esa Tuomaala

Adapting CCA and Receiver Sensitivity

Date: 2014-11-03

Authors:

Name Affiliations Address Phone email

Hossein-Ali Safavi-Naeini

Esa Tuomaala Olli Alanen

Sayantan Choudhury Enrico Rantala Jarkko Kneckt

Nokia

2075 Allston Way #200

Berkeley, CA 94704, USA

esa.tuomaala@nokia.com

Slide 1

November 2014

doc.: IEEE 802.11-14/1443r0

Submission

Background

• CCA/Receiver Sensitivity– Threshold governing packet reception (decode NAV and deferral)– More aggressive threshold governing pure energy detection

• Maximum threshold defined by the standard– Vendors are free to have more ‘sensitive’ receivers (e.g. -90dBm vs. -82

dBm)

• Modifying CCA has shown various levels of gain [1-6]– Uniform thresholds have shown mixed results

• Adaptive thresholds proposed in [7]

November 2014

Esa TuomaalaSlide 2

doc.: IEEE 802.11-14/1443r0

Submission

This Contribution

• Scenario 1 simulations shown with varying receiver sensitivities

• Demonstrating the unfairness in per-floor throughput• Impact of local adaptation of thresholds (per-floor basis)

November 2014

Esa TuomaalaSlide 3

doc.: IEEE 802.11-14/1443r0

Submission

Contention Domains

November 2014

Esa TuomaalaSlide 4

• Relative size of contention domains affects throughput– More contention for crowded areas– Less contention in certain spots (e.g. building edges)

• Easily observed in the 11ax scenarios (e.g. Scenario 1)

-82dBm

doc.: IEEE 802.11-14/1443r0

Submission

• In a dense deployment, not all STAs/APs experience the same conditions

• Multiple parameters could be adjusted to improve fairness– EDCA parameters: adjust contention window, TXOP duration,

etc…– CCA/Receiver Sensitivity/Color bit: shrink deferral radius

• The above parameters can be optimized to improve spatial reuse while maintaining fairness

November 2014

Esa TuomaalaSlide 5

Improving Fairness

doc.: IEEE 802.11-14/1443r0

Submission

• Centralized– Feasible in managed environments (e.g. corporate setting)– Can arrive at a better solution according to given metrics (e.g. 5%

throughput)

• Distributed– Using beacons or inter-AP communication to set per BSS

parameters– AP could assign parameters to all associated STAs (RAW concept)– Hybrid approach possible (centralized in-BSS, distributed inter-

BSS)

November 2014

Esa TuomaalaSlide 6

Adjusting Parameters

doc.: IEEE 802.11-14/1443r0

Submission

Scenario 1 (Residential) : Setup

• Assumptions:– 1 AP Per apartment– 2 STAs per AP – Uplink only traffic (full buffer AC2)– Fading OFF– 11ax Scenario 1 Pathloss formula– AP: 21dBm, STA: 15dBm

• Parameters:– Fixed MCS: 256QAM ¾– RTS/CTS OFF– 80 MHz Channel (single channel)– Max Number of AMPDUs: 64

November 2014

Esa TuomaalaSlide 7

Residential Scenario [8]

Floor layout

10 m

10 m

3 m

doc.: IEEE 802.11-14/1443r0

Submission

Scenario 1 (Residential) : Results

• Floor plots– Average throughput per apartment over a large number of drops– Each drop with random node positioning– Results displayed in Kbps

• CDFs:– Per floor throughput for all nodes in all drops– Clear symmetries in floors 1,5 and 2,4 as expected

November 2014

Esa TuomaalaSlide 8

doc.: IEEE 802.11-14/1443r0

Submission

• Receiver sensitivity: -90dBm• Floors 1,5 get much better

throughput than 2-4• Significant difference in floor

throughput (unfair)

November 2014

Esa TuomaalaSlide 9

Default (-90dBm)

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

90 d

Bm

) Mean: 32330.46, 5th: 3746.67, 50th: 26652.00, 90th: 66782.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

90 d

Bm

) Mean: 23445.57, 5th: 2960.00, 50th: 18741.33, 90th: 48629.33

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

90 d

Bm

)

Mean: 24836.46, 5th: 3408.00, 50th: 21014.67, 90th: 50174.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

90 d

Bm

)

Mean: 23914.38, 5th: 3032.00, 50th: 19268.00, 90th: 49141.33

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

90 d

Bm

)

Mean: 31728.41, 5th: 3665.33, 50th: 25937.33, 90th: 66589.33

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-90 dBm)Floor 2 (-90 dBm)Floor 3 (-90 dBm)Floor 4 (-90 dBm)Floor 5 (-90 dBm)

floo

rs 2

-4 w

ith

wor

se th

roug

hput

better throughput at edge

doc.: IEEE 802.11-14/1443r0

Submission

• Receiver sensitivity: -82dBm• Overall throughput is improved• Floors 2-4 still receive poor

throughput compared to 1,5

November 2014

Esa TuomaalaSlide 10

-82 dBm

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

82 d

Bm

) Mean: 33310.54, 5th: 2816.00, 50th: 25986.67, 90th: 72296.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

82 d

Bm

) Mean: 24994.66, 5th: 2353.33, 50th: 18478.67, 90th: 55752.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

82 d

Bm

)

Mean: 25774.92, 5th: 2686.67, 50th: 20080.00, 90th: 55014.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

82 d

Bm

)

Mean: 24759.61, 5th: 2244.00, 50th: 18669.33, 90th: 54540.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

82 d

Bm

)

Mean: 33830.90, 5th: 2985.33, 50th: 27025.33, 90th: 72049.33

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-82 dBm)Floor 2 (-82 dBm)Floor 3 (-82 dBm)Floor 4 (-82 dBm)Floor 5 (-82 dBm)

wor

se th

roug

hput

better throughput at edge

doc.: IEEE 802.11-14/1443r0

Submission

• Receiver sensitivity: -72dBm• General picture improves

November 2014

Esa TuomaalaSlide 11

-72 dBm

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

72 d

Bm

) Mean: 36027.55, 5th: 2504.00, 50th: 26908.00, 90th: 80460.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

72 d

Bm

) Mean: 28525.87, 5th: 2049.33, 50th: 21029.33, 90th: 64773.33

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

72 d

Bm

)

Mean: 31850.44, 5th: 2766.67, 50th: 24538.67, 90th: 69408.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

72 d

Bm

)

Mean: 28801.55, 5th: 2072.00, 50th: 21405.33, 90th: 64348.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

72 d

Bm

)

Mean: 36195.57, 5th: 2158.67, 50th: 26914.67, 90th: 80753.33

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-72 dBm)Floor 2 (-72 dBm)Floor 3 (-72 dBm)Floor 4 (-72 dBm)Floor 5 (-72 dBm)

doc.: IEEE 802.11-14/1443r0

Submission

• More ‘fair’ by using per-floor thresholds

• No optimization done for best thresholds

• 5th percentile suffers on some floors

November 2014

Esa TuomaalaSlide 12

-86,-65,-62,-65,-86 dBm

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

86 d

Bm

) Mean: 31785.19, 5th: 3320.00, 50th: 25334.67, 90th: 67128.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

65 d

Bm

) Mean: 30276.23, 5th: 1798.67, 50th: 21404.00, 90th: 70165.33

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

62 d

Bm

)

Mean: 31525.27, 5th: 1797.33, 50th: 23024.00, 90th: 73062.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

65 d

Bm

)

Mean: 31179.42, 5th: 1824.00, 50th: 21854.67, 90th: 72512.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

86 d

Bm

)

Mean: 31336.08, 5th: 3205.33, 50th: 24948.00, 90th: 67998.67

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-86 dBm)Floor 2 (-65 dBm)Floor 3 (-62 dBm)Floor 4 (-65 dBm)Floor 5 (-86 dBm)

alm

ost u

nifo

rm th

roug

hput

per

flo

or (

fair

)

better throughput persists

doc.: IEEE 802.11-14/1443r0

Submission

Scenario 1 (Alternate Pathloss)

• Same as previous setup, only pathloss is modified:– Floor penetration loss is 10dB per floor, wall loss remains at 5dB

• How scenario dependent are the thresholds?– How adaptive should they be?

November 2014

Esa TuomaalaSlide 13

doc.: IEEE 802.11-14/1443r0

Submission

• Receiver sensitivity: -82dBm• Floor 3 has better throughput

because floors 2,4 rarely transmit• Very different results compared to

prior pathloss model

November 2014

Esa TuomaalaSlide 14

-82 dBm (alternate PL)

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

82 d

Bm

) Mean: 33881.01, 5th: 3845.33, 50th: 29986.67, 90th: 66132.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

82 d

Bm

) Mean: 18835.16, 5th: 3785.33, 50th: 17648.00, 90th: 32284.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

82 d

Bm

)

Mean: 24515.80, 5th: 2314.67, 50th: 22626.67, 90th: 45954.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

82 d

Bm

)

Mean: 18804.87, 5th: 3770.67, 50th: 18065.33, 90th: 31846.67

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

82 d

Bm

)

Mean: 34295.15, 5th: 4025.33, 50th: 30424.00, 90th: 66870.67

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-82 dBm)Floor 2 (-82 dBm)Floor 3 (-82 dBm)Floor 4 (-82 dBm)Floor 5 (-82 dBm)

doc.: IEEE 802.11-14/1443r0

Submission

• Receiver sensitivity: -72dBm• Some improvements, but floors 2 &

4 continue to do poorly

November 2014

Esa TuomaalaSlide 15

-72 dBm (alternate PL)

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

1 (-

72 d

Bm

) Mean: 35679.37, 5th: 3150.67, 50th: 30785.33, 90th: 72736.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

2 (-

72 d

Bm

) Mean: 20253.89, 5th: 2930.67, 50th: 18284.00, 90th: 37412.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

3 (-

72 d

Bm

)

Mean: 27837.03, 5th: 1778.67, 50th: 24621.33, 90th: 56140.00

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

4 (-

72 d

Bm

)

Mean: 20422.10, 5th: 3109.33, 50th: 18698.67, 90th: 37361.33

Kbp

s

2

4

6x 10

4

0 10 20 30 40 50 60 70 80 90 1000

10

20

Flo

or

5 (-

72 d

Bm

)

Mean: 35979.57, 5th: 2930.67, 50th: 30817.33, 90th: 74036.00

Kbp

s

2

4

6x 10

4

0 1 2 3 4 5 6 7 8 9 10 11

x 104

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Kbps

F(x

)

Empirical CDF

Floor 1 (-72 dBm)Floor 2 (-72 dBm)Floor 3 (-72 dBm)Floor 4 (-72 dBm)Floor 5 (-72 dBm)

doc.: IEEE 802.11-14/1443r0

Submission

Conclusion

• Fundamental Unfairness– With fixed thresholds, we show that there is unfairness (based on location,

interference, etc.)– The unfairness can be mitigated by intelligent selection of thresholds

• Results are scenario dependent– Results are sensitive to path loss parameters and scenario setup

• We show that adaptive configuration of CCA threshold or receiver sensitivity can help improve spatial reuse while maintaining fairness

November 2014

Esa TuomaalaSlide 16

doc.: IEEE 802.11-14/1443r0

Submission

References[1] IEEE 802.11-14/0082r0 – Improved Spatial Reuse Feasibility – Part I

[2] IEEE 802.11-14/0083r0 – Improved Spatial Reuse Feasibility – Part II

[3] IEEE 802.11-14/0372r2 – System Level Simulations on Increased Spatial Reuse

[4] IEEE 802.11-14/846r1 – Changing CCA in the Residential Environment

[5] IEEE 802.11-14/861r0 – Impact of CCA adaptation on spatial reuse in dense residential scenario

[6] IEEE 802.11-14/0578r0 - Residential Scenario CCA/TPC Simulation Discussion

[7] IEEE 802.11-14/1233r2 – Adaptive CCA for 11ax

[8] IEEE 802.11-14/0621r4 – TGax Simulation Scenarios

November 2014

Esa TuomaalaSlide 17