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Balancing Uplink and Downlin Balancing Uplink and Downlin k Delay of VoIP Traffic in 8 k Delay of VoIP Traffic in 8 02.11 WLANs 02.11 WLANs Sangho Shin Henning Schulzrinne Columbia University Department of Computer Science

Balancing Uplink and Downlink Delay of VoIP Traffic in 802.11 WLANs

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Balancing Uplink and Downlink Delay of VoIP Traffic in 802.11 WLANs. Sangho Shin Henning Schulzrinne Columbia University Department of Computer Science. Motivation. VoIP in IEEE 802.11 WLANs. Distribution Network (DS). Access Point (AP). STAs. 1/30. Motivation. - PowerPoint PPT Presentation

Text of Balancing Uplink and Downlink Delay of VoIP Traffic in 802.11 WLANs

  • Balancing Uplink and Downlink Delay of VoIP Traffic in 802.11 WLANs

    Sangho ShinHenning SchulzrinneColumbia UniversityDepartment of Computer Science

  • MotivationVoIP in IEEE 802.11 WLANsDistribution Network (DS)1/30Access Point (AP)STAs

  • MotivationVoIP in IEEE 802.11 WLANs1/30Access Point (AP)STAsDistribution Network (DS)

  • MotivationVoIP in IEEE 802.11 WLANs1/30Access Point (AP)STAsDistribution Network (DS)

  • Motivation20 ms packetization interval (64kb/s)2/30DownlinkUplink

    Chart1

    1.97.61.45.3

    2.3141.56

    2.5401.617

    2.8691.719

    31801.8754

    2.962491.9116

    2.963812191

    3.34602.15330

    3.675042.3390.9

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet1

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)Fairness index

    261.97.61.45.30.97

    272.3141.560.97

    282.5401.6170.976

    292.8691.7190.975

    3031801.87540.975

    312.962491.91160.978

    322.9638121910.976

    333.34602.153300.974

    343.675042.3390.90.971

    Sheet1

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet2

    00000

    00000

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    00000

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    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Fairness index

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet3

  • MotivationWhen the channel is congested .3/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • MotivationWhen the channel is congested .3/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • MotivationWhen the channel is congested .3/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • MotivationWhen the channel is congested .3/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • MotivationWhen the channel is congested .3/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • MotivationSolutions?Give a higher priority to the AP than STAs4/30QueueQueueQueueQueueQueueDistribution Network (DS)

  • OutlineBackgroundAdaptive Priority Control (APC)Simulation resultsImplementation IssuesConclusionsFuture work

    5/30

  • BackgroundMedium Access in DCF (Distributed Coordination Function)Number of Backoff = (0, CWmin)6/30

  • BackgroundHow to control the priority of the AP?Inter-Frame Spacing (IFS)Contention Window (CW) Contention Free TransmissionBusy MediumDIFSDIFSFrameContention WindowBackoffDefer AccessSlot time7/30

  • Transmission ControlControl Contention Window (CW)

    DIFSDIFSBOSTAAPFrameBO1DIFSDefer AccessBO2DIFSBOFrameDefer AccessDIFSBODIFSBOBOBOFrameDefer Access8/30Remaining BO time

  • Transmission ControlControl Contention Window (CW)It is hard to control the priority accurately.Backoff time is randomly decided between (0, CWmin).Shorter CW Higher collision probabilityDecrease the capacity.

    9/30

  • Transmission ControlControl IFSSTA2APFrameDIFSDefer AccessBOBOFrameDefer AccessFrameIFSSTA1Defer AccessDIFS10/30

  • Transmission ControlContention Free Transmission (CFB)

    Control the number of frames (P)11/30

  • Transmission ControlContention Free Transmission (CFB)Precise priority control P PriorityTransmitting three frames contention free three times higher priority than other STAs.No overhead

    12/30

  • Adaptive Priority ControlOptimal priority of the AP to balance the uplink and downlink delay ?Number of active wireless STAs Semi-Adaptive Method13/30

  • Semi-Adaptive10 packetsP = 4

  • Semi-Adaptive6 packetsP = 4

  • Adaptive Priority ControlOptimal priority of the AP to balance the uplink and downlink delay ?Number of active wireless STAs Semi-Adaptive MethodSimpleAdaptive to the change of the number of active wireless STAs.Not adaptive to the change of the traffic volume of uplink and downlink.13/30

  • Semi-Adaptive

  • Adaptive Priority ControlOptimal priority of the AP to balance the uplink and downlink delay ?Uplink/Downlink delay Queuing delay

    The same packet processing time in Queue of the AP and STAs The same queuing delayAccess delayPropagation delay14/30

  • Adaptive Priority Control Optimal Priority = QAP/QSTA (QSTA>0)15/30

  • APC10 packetsP = 10 / 2 = 5

  • APC10 packetsP = 10 / 2 = 5

  • APCP = 5/1 = 55 packets

  • Adaptive Priority ControlOptimal Priority = QAP/QSTASimpleAdaptive to change of number of active STAsAdaptive to change of uplink/downlink traffic volumeResults in the same packet processing time between the AP and STAs same queuing delay in the AP and STAs same uplink and downlink delay15/30

  • Simulation Results2/30

    - DCF

  • Simulation Results20 ms packetization interval (64kb/s)16/30

    Semi-Adaptive Method

    Chart2

    4.72.62.819671.40139

    12.54842.774193.900111.96083

    9.6259.3754.180762.55917

    15.909117.121210.09166.00173

    31.794127.411818.815510.7216

    55.542977.542920.620925.3382

    141.528176.41740.256258.0439

    222.243325.86585.682112.767

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.72.62.819671.40139

    3112.54842.774193.900111.96083

    329.6259.3754.180762.55917

    3315.909117.121210.09166.00173

    3431.794127.411818.815510.7216

    3555.542977.542920.620925.3382

    36141.528176.41740.256258.0439

    37222.243325.86585.682112.767

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results - APC20 ms packetization interval (64kb/s)17/30

    Chart1

    4.766672.72.822571.4251

    6.322582.677424.055881.97628

    9.87511.28124.030442.73165

    15.606119.484810.15766.4575

    28.705927.558817.283112.0796

    54.828662.142921.732219.8677

    168.444153.11152.214753.5176

    404.324351.649115.236125.452

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.766672.72.822571.4251

    316.322582.677424.055881.97628

    329.87511.28124.030442.73165

    3315.606119.484810.15766.4575

    3428.705927.558817.283112.0796

    3554.828662.142921.732219.8677

    36168.444153.11152.214753.5176

    37404.324351.649115.236125.452

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results APC vs Semi-Adaptive20 ms packetization interval (64kb/s)Semi-AdaptiveAPC18/30

    Chart2

    4.72.62.819671.40139

    12.54842.774193.900111.96083

    9.6259.3754.180762.55917

    15.909117.121210.09166.00173

    31.794127.411818.815510.7216

    55.542977.542920.620925.3382

    141.528176.41740.256258.0439

    222.243325.86585.682112.767

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.72.62.819671.40139

    3112.54842.774193.900111.96083

    329.6259.3754.180762.55917

    3315.909117.121210.09166.00173

    3431.794127.411818.815510.7216

    3555.542977.542920.620925.3382

    36141.528176.41740.256258.0439

    37222.243325.86585.682112.767

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Chart1

    4.766672.72.822571.4251

    6.322582.677424.055881.97628

    9.87511.28124.030442.73165

    15.606119.484810.15766.4575

    28.705927.558817.283112.0796

    54.828662.142921.732219.8677

    168.444153.11152.214753.5176

    404.324351.649115.236125.452

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.766672.72.822571.4251

    316.322582.677424.055881.97628

    329.87511.28124.030442.73165

    3315.606119.484810.15766.4575

    3428.705927.558817.283112.0796

    3554.828662.142921.732219.8677

    36168.444153.11152.214753.5176

    37404.324351.649115.236125.452

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results DCF vs APC20 ms packetization interval (64kb/s)Capacity = 28Capacity = 35DCFAPC19/30

    Chart1

    4.766672.72.822571.4251

    6.322582.677424.055881.97628

    9.87511.28124.030442.73165

    15.606119.484810.15766.4575

    28.705927.558817.283112.0796

    54.828662.142921.732219.8677

    168.444153.11152.214753.5176

    404.324351.649115.236125.452

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.766672.72.822571.4251

    316.322582.677424.055881.97628

    329.87511.28124.030442.73165

    3315.606119.484810.15766.4575

    3428.705927.558817.283112.0796

    3554.828662.142921.732219.8677

    36168.444153.11152.214753.5176

    37404.324351.649115.236125.452

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Chart1

    1.97.61.45.3

    2.3141.56

    2.5401.617

    2.8691.719

    31801.8754

    2.962491.9116

    2.963812191

    3.34602.15330

    3.675042.3390.9

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet1

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)Fairness index

    261.97.61.45.30.97

    272.3141.560.97

    282.5401.6170.976

    292.8691.7190.975

    3031801.87540.975

    312.962491.91160.978

    322.9638121910.976

    333.34602.153300.974

    343.675042.3390.90.971

    Sheet1

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet2

    00000

    00000

    00000

    00000

    00000

    00000

    00000

    00000

    00000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Fairness index

    Number of VoIP sources

    End-to-end delay (ms)

    Sheet3

  • Simulation Results - APC20/30

  • Simulation Results Semi-Adaptive Method10ms + 20 ms packetization interval (64kb/s)21/30

    Chart6

    3.321.915311.1459

    5.142864.142863.052232.23253

    64.954553.544752.91741

    13.347822.34787.229376.7322

    4795.291716.205828.4912

    140.6319.5645.3439143.37

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    203.321.915311.1459

    215.142864.142863.052232.23253

    2264.954553.544752.91741

    2313.347822.34787.229376.7322

    244795.291716.205828.4912

    25140.6319.5645.3439143.37

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results - APC10ms + 20 ms packetization interval (64kb/s)22/30

    Chart3

    3.321.915311.1459

    5.333334.380953.245322.37437

    5.863644.681823.585592.67533

    13.695723.52176.997776.76429

    55.37577.041718.215323.4618

    177.24197.5262.076286.7934

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    203.321.915311.1459

    215.333334.380953.245322.37437

    225.863644.681823.585592.67533

    2313.695723.52176.997776.76429

    2455.37577.041718.215323.4618

    25177.24197.5262.076286.7934

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results APC vs Semi-Adaptive Method10ms + 20 ms packetization interval (64kb/s)Semi-AdaptiveAPC23/30

    Chart3

    3.321.915311.1459

    5.333334.380953.245322.37437

    5.863644.681823.585592.67533

    13.695723.52176.997776.76429

    55.37577.041718.215323.4618

    177.24197.5262.076286.7934

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    203.321.915311.1459

    215.333334.380953.245322.37437

    225.863644.681823.585592.67533

    2313.695723.52176.997776.76429

    2455.37577.041718.215323.4618

    25177.24197.5262.076286.7934

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    Chart6

    3.321.915311.1459

    5.142864.142863.052232.23253

    64.954553.544752.91741

    13.347822.34787.229376.7322

    4795.291716.205828.4912

    140.6319.5645.3439143.37

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    203.321.915311.1459

    215.142864.142863.052232.23253

    2264.954553.544752.91741

    2313.347822.34787.229376.7322

    244795.291716.205828.4912

    25140.6319.5645.3439143.37

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results - APC40 ms packetization interval (64kb/s)24/30

    Chart5

    9.309093.418185.520951.90026

    10.66073.8756.303242.05865

    13.26325.56147.749343.21104

    24.517213.017215.42195.96477

    40.508537.711924.535513.1698

    160.667136.1561.565741.6489

    421.852233.607138.598105.214

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    559.309093.418185.520951.90026

    5610.66073.8756.303242.05865

    5713.26325.56147.749343.21104

    5824.517213.017215.42195.96477

    5940.508537.711924.535513.1698

    60160.667136.1561.565741.6489

    61421.852233.607138.598105.214

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Simulation Results - APC20 ms + 40 ms packetization interval (64kb/s)25/30

    Chart4

    5.263162.368422.851681.36749

    6.102562.717953.719091.63937

    6.853.253.840731.72465

    11.39025.536596.91633.36206

    15.452410.071410.53945.7227

    23.18614.790710.73775.45753

    43.636450.977323.654316.4241

    119.511118.17844.640340.9274

    207.69614972.169669.1486

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    385.263162.368422.851681.36749

    396.102562.717953.719091.63937

    406.853.253.840731.72465

    4111.39025.536596.91633.36206

    4215.452410.071410.53945.7227

    4323.18614.790710.73775.45753

    4443.636450.977323.654316.4241

    45119.511118.17844.640340.9274

    46207.69614972.169669.1486

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Implementation IssuesHow can the AP know the queue size of nodes?Add the queue size of each node to VoIP packets.It requires the changes in clientsEstimate the average queue size of nodesQueue size = Number of packets generated at APP layer Number of packets transmittedNumber of packets transmitted Number of packets receivedNumber of packets generated at APP layer Number of active nodes x packetization interval

    26/30

  • Implementation Issues APC with estimated Queue size27/30

    Chart1

    4.72.733332.763391.51311

    5.967743.096773.728382.20353

    9.687513.06253.962722.80549

    13.969720.060610.25716.30142

    27.852926.588215.1910.9343

    5858.657121.867920.9586

    137.472159.19447.116849.5646

    374.622302.703114.66103.368

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

    AQ

    Uplink (90th%tile)Downlink (90th%tile)Uplink (AVG)Downlink (AVG)

    304.72.733332.763391.51311

    315.967743.096773.728382.20353

    329.687513.06253.962722.80549

    3313.969720.060610.25716.30142

    3427.852926.588215.1910.9343

    355858.657121.867920.9586

    36137.472159.19447.116849.5646

    37374.622302.703114.66103.368

    AQ

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    0000

    Uplink (90th%tile)

    Downlink (90th%tile)

    Uplink (AVG)

    Downlink (AVG)

    Number of VoIP sources

    End-to-end delay (ms)

  • Implementation IssuesHow to implement Contention Free Transmission?IEEE 802.11e : Contention Free Bursty (CFB)Change the CFB duration.Wireless Media Extension (WME)A subset of IEEE 802.11eImplemented in many chipsetsAllows change of IFS, CFB duration28/30

  • ConclusionsUplink and downlink delay VoIP traffic in DCF are significantly unbalanced.APC, in which AP transmits QAP/QNodes packets, balances the uplink and downlink delay.APC improves the capacity for VoIP traffic from 28 calls to 35 calls, by 25%.29/30

  • Future WorkIntegrate APC to IEEE 802.11e.Measure the performance of APC with background traffic.Measure the performance of APC with actual wireless nodes in ORBIT test-bed.

    30/30

  • Thank you

    Questions?

  • MotivationVoIP in IEEE 802.11 WLANsDistributed Network (DS)

  • SimulationsVoIP traffic modelITU-T P59

    Our Model

    Duration (s)Rate (%)0.937.51.562.5000.325.0