Submission

doc.: IEEE 11-14/0868r0July 2014

Johan Söder, Ericsson ABSlide 1

UL & DL DSC and TPC MAC simulationsDate: 2014-07-14

Name Affiliations Address Phone email Johan Söder Ericsson AB Färögatan 6, Stockholm,

Sweden +46 722449170 johan.soder

@ericsson.com Filip Mestanov Ericsson AB filip.mestanov

@ericsson.com Leif Wilhelmsson Ericsson AB leif.r.wilhelmsson

@ericsson.com Hakan Persson Ericsson AB hakan.z.persson

@ericsson.com Kåre Agardh Sony Mobile kare.agardh

@sonymobile.com

Bill Carney Sony USTSO William.Carney @am.sony.com

Kazuyuki Sakoda Sony ITDD KazuyukiA.Sakoda @jp.sony.com

Authors:

Submission

doc.: IEEE 11-14/0868r0July 2014

Johan Söder, Ericsson ABSlide 2

Abstract

In this presentation we share system simulations results obtained from the evaluation of a Dynamic Sensitivity

Control (DSC) mechanism (for both UL and DL) as well as results evaluating the potential of Transmission Power

Control (TPC)

Submission

doc.: IEEE 11-14/0868r0July 2014

Johan Söder, Ericsson ABSlide 3

Context

• DSC [1], [2] has been shown to provide performance improvements in UL

• However, the majority of the traffic is still in DL direction; hence DL optimization techniques need also be considered

• Transmit Power Control (TPC) is another proposed feature that shows promising results

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

Simulation scenario 2:Enterprise

Slide 4

July 2014

› “Enterprise Scenario” as defined in [3]• 8 offices, 64 cubicles per office, 2 STAs

per cubicle • (8 x 64 x 2) / 32 = 32 STA/AP

• 4 x 20MHz channels (8 APs on the same channel)

• 32 x 8 = 256 STAs on the same channel

• COST231 propagation model› Web-browsing and local file transfer

AP<->STA

› No P2P links included

BSS9-12 BSS13-16 BSS24-28 BSS29-32

BSS1-4 BSS5-8 BSS17-19 BSS20-23

20 m

20 m

STA1

STA2

STA3

2 m

2 m

STA4

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

Simulation assumptions

• MAC layer simulator

• 802.11n

• Tx Power AP = 20dBm

• Tx Power STA = 20dBm

• Antennas AP: 2Tx, 2Rx

• Antennas STA: 2Tx, 2Rx

• Reference CCAT = -82dBm

Slide 5

July 2014

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

Traffic assumptions

• Files arrive independently in the buffers of the STAs(UL) and the APs (DL, files labelled with a receiver STA)

• Arrival process is a Poisson process

• Arrival intensity of DL and UL files has ratio 80/20

• Different system loads are modelled by varying arrival intensity, the file size is kept constant

• Sample file size is 1MB

Slide 6

July 2014

Submission

doc.: IEEE 11-14/0868r0

Definitions

• Packet throughput = packet size / packet delay

• Packet delay = time from packet arrives in buffer until time the last ACK is received

• User throughput = average of packet throughputs for a user

• Served traffic = Sum of all successfully received packets / simulation time

• Served traffic ~ system arrival intensity * packet size

Slide 7 Johan Söder, Ericsson AB

July 2014

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

UL:Dynamic sensitivity control

• The DSC mechanism evaluated in this work consists of each STA autonomously setting their respective Rx sensitivity threshold as:

RxSensT= RSSI – MAR• RSSI is received signal strength from AP

• MAR is a parameter that controls how aggressive the algorithm is

• CCA threshold (CCAT) is set as:• CCAT = max(CCAT_default, RxSensT)

• In these evaluations MAR = 15dB

Slide 8

July 2014

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

• The AP per-link CCAT evaluated in this work consists of the AP setting an individual CCAT for each STA:

CCATA = max(CCATDefault, RSSIA – MARA )

CCATB = max(CCATDefault, RSSIB – MARB )

• RSSIA, B are the received signal strength for

STAs A and B respectively

• MARA, B are parameters that controls

how aggressive the algorithm is

• In these evaluations MARA = MARA = 15dB

DL:AP per-link CCAT adaptation

July 2014

Slide 9

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

0 5 10 15 20 250

20

40

60

80

100

120

140

Served traffic per AP (DL+UL) [Mbps]

Fif

th P

erc

en

tile

Us

er

Th

rou

gh

pu

t [M

bp

s]

Ref [DL]Ref [UL]DSC [DL]DSC [UL]DSC+AP Per-Link CCAT [DL]DSC+AP Per-Link CCAT [UL]

0 5 10 15 20 250

20

40

60

80

100

120

140

Served traffic per AP (DL+UL) [Mbps]

Fif

th P

erc

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tile

Us

er

Th

rou

gh

pu

t [M

bp

s]

Ref

DSCDSC+AP Per-Link CCAT [DL]

Enterprise scenario:Sensitivity control

Some gains from DSC in user throughput for all links (left figure), mainly impacts the UL (right figure)

DSC in combination with AP per-link CCAT shows great potential, improves both DL & UL user throughput

July 2014

Slide 10

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

0 5 10 15 20 250

10

20

30

40

50

60

Served traffic per AP (DL+UL) [Mbps]

DL

SIN

R (

Me

an

an

d 5

th p

erc

) [d

B]

RefDSCDSC+AP Per-Link CCAT [DL]

2 4 6 8 10 12 140

1

2

3

4

5

6x 10

-5

Served traffic per AP (DL+UL) [Mbps]

De

lay

[s

]

Queuing

Contention

Collision

SINR and Delay time

DL SINR is reduced but still very high

Queuing time is reduced

Slide 11

July 2014

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

Enterprise scenario:Combined results

Capacity for 20Mbps user throughput requirement (95%)

Slide 12

July 2014

Ref UL DSC DL+UL DSC 0

5

10

15

20

25

System capacity [Mbps/AP]

30%

90%

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

Transmit power control (TPC)

• DL power reduction: DL power is set to reach a target SNR at the potential STA location with highest pathloss• Time-varying DL TPC where the associated STA with highest

pathloss is used to set the power could also be investigated.

• Link-dependent DL TPC could also be investigated

• UL power control: UL power is set to reach a target SNR at the AP

• Target SNR DL & UL is 30dB

Slide 13

July 2014

Submission

doc.: IEEE 11-14/0868r0

Johan Söder, Ericsson AB

0 5 10 15 20 250

20

40

60

80

100

120

140

Served traffic per AP [Mbps]

Fif

th P

erc

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tile

Ob

jec

t D

ata

Ra

te [

Mb

ps

]

RefDL pwr, 30dBDL pwr+UL PC, 30dB

Enterprise scenario:Power control

Ref: DL: 20dBm, UL: 20dBm

DL Pwr: Adjust AP DL power to get target SNR at STA with highest pathloss

UL PC: Adjust STA UL power to get target SNR at AP

July 2014

Slide 14

Ref DL TPC DL+UL TPC05

10152025

System capacity [Mbps/AP]

30%77%

Submission

doc.: IEEE 11-14/0868r0July 2014

Johan Söder, Ericsson ABSlide 15

Conclusion

• DSC improves performance in UL

• Setting the CCAT at AP (for transmission in DL) gives improvements in DL

• Combining DSC and DL CCAT setting gives a well balanced UL & DL performance.

• TPC gives system capacity gains

Submission

doc.: IEEE 11-14/0868r0July 2014

Johan Söder, Ericsson ABSlide 16

References

[1] 11-14-0779-00-00ax-dsc-practical-usage

[2] 11-14-0523-00-00ax-mac-simulation-results-for-dsc-and-tpc

[3] 11-14-0621-04-00ax-simulation-scenarios