audio streaming over bluetooth scatternet: using adaptive link layer

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Audio Streaming over Audio Streaming over Bluetooth Scatternet: Bluetooth Scatternet: using Adaptive Link using Adaptive Link LayerLayer

Team members: Sewook Jung, Jungsoo Lim, Soon Young Team members: Sewook Jung, Jungsoo Lim, Soon Young OhOh

Tutor: Ling-Jyh ChenTutor: Ling-Jyh Chen

Professor Mario GerlaProfessor Mario Gerla

CS218 – Fall 2003CS218 – Fall 2003

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OutlinesOutlines

BackgroundBackground Adaptive Automatic Retransmission Adaptive Automatic Retransmission

ReQuest (ARQ) Retransmission ReQuest (ARQ) Retransmission Timeout (RTO)Timeout (RTO)

Previous ResearchPrevious Research Related workRelated work ImplementationsImplementations SimulationsSimulations ConclusionConclusion Future WorkFuture Work

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BackgroundBackground

Multimedia contents are prosperous Multimedia contents are prosperous – Eg. MP3 audio Eg. MP3 audio

Wireless Personal Area Network (PAN) needs Wireless Personal Area Network (PAN) needs to support multimediato support multimedia

The varying nature of the wireless link can The varying nature of the wireless link can make streaming over wireless a challenging make streaming over wireless a challenging problemproblem

Packets are arrived to client with a consistent Packets are arrived to client with a consistent raterate

44

Background (cont’d)Background (cont’d)

ARQ mechanismARQ mechanism– Packets being dropped/delayed in bad linkPackets being dropped/delayed in bad link– Beneficial to non-real-time trafficBeneficial to non-real-time traffic– Need modifications for real-time/streaming trafficNeed modifications for real-time/streaming traffic

ARQ retransmission limitARQ retransmission limit– Too highToo high

Packets are severely delayedPackets are severely delayed Streaming audio/video quality is degradedStreaming audio/video quality is degraded

– Too lowToo low large number of packets are dropped at the link layerlarge number of packets are dropped at the link layer Also causes poor audio quality.Also causes poor audio quality.

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An Adaptive ARQ RTOAn Adaptive ARQ RTO

Original BluetoothOriginal Bluetooth– stop-and-wait ARQstop-and-wait ARQ scheme at link layer scheme at link layer

packet is retransmitted until receives ACK packet is retransmitted until receives ACK or retransmission timeout (RTO) is or retransmission timeout (RTO) is exceeded.exceeded.

– In most current Bluetooth chipsetsIn most current Bluetooth chipsets the default RTO is infinitethe default RTO is infinite To provide reliable link.To provide reliable link.

– Infinite RTO degrades real-time Infinite RTO degrades real-time streaming audio/video qualitystreaming audio/video quality

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Previous ResearchPrevious Research

Fixed ARQ RTOFixed ARQ RTO– Use a fixed finite RTOUse a fixed finite RTO– Impossible to accommodate all different link Impossible to accommodate all different link

qualities with one fixed value.qualities with one fixed value. Adaptive ARQ RTOAdaptive ARQ RTO

– Adjust RTO by measurement of previous RTTAdjust RTO by measurement of previous RTT– Improvement on average delay time and the Improvement on average delay time and the

packet success ratepacket success rate

RTT increase --RTT increase --decrease ARQ RTOdecrease ARQ RTO

RTT decrease --RTT decrease -- increase ARQ RTOincrease ARQ RTO

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Previous Research Previous Research (cont’d)(cont’d)

The RTO equationThe RTO equationSRTT’ = (1- SRTT’ = (1- ) X SRTT + ) X SRTT + X RTT X RTT (1)(1)

X RTO; if RTT < SRTTX RTO; if RTT < SRTT (2)(2)

RTO’ =RTO’ = X RTO; if RTT > SRTT X RTO; if RTT > SRTT

RTO; if previous packet is RTO; if previous packet is droppeddropped

SRTT = smooth RTT, SRTT = smooth RTT, = 1.1 = 1.1 ββ = 0.9 = 0.9 = 0.25 = 0.25

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Previous Research Previous Research (cont’d)(cont’d) Set the upper bound and lower Set the upper bound and lower

bound for ARQ RTObound for ARQ RTO RTORTOmin min = 2 X T= 2 X Tpackets packets (= 6*625ms in (= 6*625ms in

DH5)DH5) RTORTOmax max = T= Tpackets packets X Max(Available Buffer X Max(Available Buffer

X 75%, 2)X 75%, 2)TTpacketpacket = time interval between first packet = time interval between first packet fragments and last fragments’ ACKfragments and last fragments’ ACKAvailable buffer = (system maximum input Available buffer = (system maximum input buffer – buffer – used buffer)/packet size used buffer)/packet size

99

Previous Research Previous Research (cont’d)(cont’d) Adaptive ARQ RTO ResultsAdaptive ARQ RTO Results

– Enhance the streaming audio quality Enhance the streaming audio quality remarkablyremarkably

– Robust solution for Robust solution for real-time/streaming data over real-time/streaming data over wireless network.wireless network.

1010

Related workRelated work

TCP-Friendly Rate Control (TFRC): TCP-Friendly Rate Control (TFRC): equation based TCP rate controlequation based TCP rate control

Video Transport Protocol (VTP): sender Video Transport Protocol (VTP): sender adjust the sending rate based on adjust the sending rate based on estimated eligible rateestimated eligible rate

RAP: End-to-end Rate Based Control: RAP: End-to-end Rate Based Control: mimics TCP’s AIMD behaviormimics TCP’s AIMD behavior

RCS: A Rate Control Scheme: source RCS: A Rate Control Scheme: source probes the connection with dummy probes the connection with dummy packets, and adjust sending ratepackets, and adjust sending rate

1111

ImplementationsImplementations

Blueware: Blueware: – Developed by MITDeveloped by MIT– Bluetooth simulator as an extension Bluetooth simulator as an extension

to NSto NS– Various Scatternet formation and Various Scatternet formation and

link scheduling schemes.link scheduling schemes.

1212

Implementations Implementations (cont’d) (cont’d)

Applications

L2CAP

Bluetooth Radio

Host Controller Interface

Bluetooth Baseband

LMP

Bluetooth Stack

1313

Implementations Implementations (cont’d) (cont’d)

Topology formationTopology formation Manipulate the topology formationManipulate the topology formation

– Set position of nodes manuallySet position of nodes manually– Original Blueware has only random topology formationOriginal Blueware has only random topology formation

The examples of topology formations:The examples of topology formations:

1 hop 2 hops 3 hops

2 flows 3 flows

1414

Implementations Implementations (cont’d)(cont’d)Original MethodOriginal MethodApplication L2CAPApplication L2CAP L2CAP HCI/LCL2CAP HCI/LC Receiver Receiver

LayerLayer Queue Queue Layer LayerLayer Layer

RTT < RTO

RTT

Partial RTT

1515

Implementations Implementations (cont’d)(cont’d)Original MethodOriginal MethodApplication L2CAPApplication L2CAP L2CAP HCI/LCL2CAP HCI/LC Receiver Receiver


Partial RTT > RTO

RTT

Partial RTT HCI_FLUSH

1616

Implementations Implementations (cont’d)(cont’d) Next Packet Drop Next Packet DropApplication L2CAPApplication L2CAP HCI/LCHCI/LC ReceiverReceiver

LayerLayer Layer Layer LayerLayer

RTT1 < RTO

RTT1

RTT2

1717

Implementations Implementations (cont’d)(cont’d) Next Packet Drop Next Packet DropApplication L2CAPApplication L2CAP HCI/LCHCI/LC ReceiverReceiver

LayerLayer Layer Layer LayerLayer

RTT1 > RTO

RTT2 < RTO

RTT1

RTT2

1818

Implementations Implementations (cont’d)(cont’d)Flow ControlFlow ControlApplication L2CAPApplication L2CAP L2CAP HCI/LCL2CAP HCI/LC Receiver Receiver


RTT < RTO

RTT

1919



RTT > RTO

RTT

2020



RTT < RTODrop Queue size = 5

RTT

2121

Implementations Implementations (cont’d)(cont’d) Generating Packet ErrorGenerating Packet Error

– Blueware supports packet error rate Blueware supports packet error rate (PER) instead of bit error rate (BER)(PER) instead of bit error rate (BER)

– DH5 mode is used for all RTP packets DH5 mode is used for all RTP packets where packet size is 2712 bits and a where packet size is 2712 bits and a packet length is five Bluetooth slotspacket length is five Bluetooth slots

– PERPER is defined as is defined asP = 1 – (1 – b)P = 1 – (1 – b)ss

b = bit error rate, s = packet size b = bit error rate, s = packet size

2222

Implementations Implementations (cont’d)(cont’d) Generating Packet Error (Cont’d)Generating Packet Error (Cont’d) Burst ErrorsBurst Errors

– once the error starts, the probability of once the error starts, the probability of having an error in the next bit is having an error in the next bit is extraordinarily high such as 90%. extraordinarily high such as 90%.

– If the burst error occurs in the middle of If the burst error occurs in the middle of the packet, it may not affect the next the packet, it may not affect the next packet.packet.

– However, if it occurs at the end of the However, if it occurs at the end of the packet, there is a great probability of packet, there is a great probability of affecting the next packet. affecting the next packet.

2323

Implementations Implementations (cont’d)(cont’d)

Good

Bad

Pbg

Pgb

PbbPgg

Burst Error transition diagramBurst Error transition diagram

Bit error rate: Bit error rate: Pgg: 1-BER Pgb: BER Pgg: 1-BER Pgb: BER

Pbb: 0.9 Pbg: 0.1Pbb: 0.9 Pbg: 0.1

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Experiment ResultsExperiment Results

Adaptive RTOAdaptive RTO2 Nodes (BER 10e-6)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

1 51 101 151 201

Number of Packets

Dela

y

0

0.05

0.1

0.15

0.2

0.25

RTT

SRTT

RTO

2525

Experiment Results Experiment Results (cont’d)(cont’d)

Next Packet Drop Thro.

0.00E+00

2.00E+04

4.00E+04

6.00E+04

8.00E+04

1.00E+05

1.20E+05

1.40E+05

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

next160

next400

next1200

fix160

fix400

fix1200

noRTO

Throughput of Next packet drop (2nodes)Throughput of Next packet drop (2nodes)

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Next Packet Drop Delay

0.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.0001 0.00001 0.000001 0.0000001 0.00000001

next160

next400

next1200

fix160

fix400

fix1200

noRTO

Delay of Next packet drop (2nodes)Delay of Next packet drop (2nodes)

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Throughput

0.00E+00

2.00E+04

4.00E+04

6.00E+04

8.00E+04

1.00E+05

1.20E+05

1.40E+05

1.60E+05

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

Bit Error Rate

Pack

et T

hrou

ghpu

t

adap160

adap400

adap1200

fix160

fix400

fix1200

noRTO

Throughput of Flow control (2nodes)Throughput of Flow control (2nodes)

2828


Packet Delay

0.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.0001 0.00001 0.000001 0.0000001 0.00000001

Bit Error Rate

Ave

rage

Del

ay T

ime

adap160

adap400

adap1200

fix160

fix400

fix1200

noRTO

Delay of Flow control (2nodes)Delay of Flow control (2nodes)

2929

Experiment Results Experiment Results (cont’d)(cont’d) Packet Success Rate with 2 NodesPacket Success Rate with 2 Nodes

2 Nodes

0.00

20.00

40.00

60.00

80.00

100.00

120.00

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

Bit Error Rate

Packet

Su

ccess R

ate

Fixed /160

Fixed /400

Fixed /1200

Adaptive /225

3030


3 Nodes

0.00

20.00

40.00

60.00

80.00

100.00

120.00

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

Bit Error Rate

Packet

Su

ccess R

ate

Fixed /160

Fixed /400

Fixed /1200

Adaptive /225

3131


5 Nodes

0.00

20.00

40.00

60.00

80.00

100.00

120.00

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

Bit Error Rate

Packet

Su

ccess R

ate

Fixed /160

Fixed /400

Fixed /1200

Adaptive /225

3232

Experiment Results (cont’d)Experiment Results (cont’d)

FairnessFairness– TopologyTopology

– Fairness in 2 flows topologyFairness in 2 flows topology– Unfairness in 3 flows topologyUnfairness in 3 flows topology

2 flows 3 flows

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0.00E+00

5.00E+04

1.00E+05

1.50E+05

2.00E+05

2.50E+05

3.00E+05

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

0->4

1->5

Total

Experiment Results (cont’d)Experiment Results (cont’d)2 Flows (Adaptive RTO : Next packet 2 Flows (Adaptive RTO : Next packet

drop)drop)

3434

Experiment Results (cont’d)Experiment Results (cont’d)3 Flows (Adaptive RTO : Next packet 3 Flows (Adaptive RTO : Next packet

drop)drop)

0.00E+00

5.00E+04

1.00E+05

1.50E+05

2.00E+05

2.50E+05

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 no error

0->5

1->6

2->7

Total

3535

Experiment Results (cont’d)Experiment Results (cont’d)3 Flows (No RTO)3 Flows (No RTO)

0.00E+00

5.00E+04

1.00E+05

1.50E+05

2.00E+05

2.50E+05

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 no Error

0->5

1->6

2->7

Total

3636

Experiment Results (cont’d)Experiment Results (cont’d)Success Rate of Random Error vs. Burst ErrorSuccess Rate of Random Error vs. Burst Error

Random Error vs. Burst Error

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08

bit error rate

Su

cces

s R

ate

(%)

Random Error

Burst Error

3737

ConclusionConclusion Success rates were about the same among Success rates were about the same among

next packet drop, flow control, and fixed next packet drop, flow control, and fixed RTO approachRTO approach

Next packet drop method improved Next packet drop method improved average delay, but throughput sufferedaverage delay, but throughput suffered

Flow control method did not improve Flow control method did not improve throughput nor delaythroughput nor delay

Unfairness detected in 3 flow topologyUnfairness detected in 3 flow topology Negligible difference in experiment results Negligible difference in experiment results

between the bit error model and the burst between the bit error model and the burst error modelerror model

3838

Future WorkFuture Work Intelligent HCI_FLUSH Intelligent HCI_FLUSH

– Previous HCI_FLUSH deletes packets based on Previous HCI_FLUSH deletes packets based on connection_handleconnection_handle

– All packets contain All packets contain connection_handle informationconnection_handle information

– HCI packet header or baseband headerHCI packet header or baseband header cid informationcid information

– L2CAP headerL2CAP header

– Remove packets which have specific connection_handle Remove packets which have specific connection_handle or cid or cid

Intelligent RTO Intelligent RTO – Adjust RTO based on jitterAdjust RTO based on jitter– New RTO equation:New RTO equation:

jitter = RTT – Tjitter = RTT – Tpacketspackets ( = 6 *625ms in DH5) ( = 6 *625ms in DH5) RTO = RTO - jitterRTO = RTO - jitter

– RTT > TRTT > Tpackets packets RTO decrease RTO decrease – RTT < TRTT < Tpackets packets RTO increaseRTO increase

3939

Future Work (cont’d)Future Work (cont’d)

Combination of Adaptive Packet Type Combination of Adaptive Packet Type (APT) and Adaptive RTO(APT) and Adaptive RTO– Combine adaptive RTO scheme with adaptive Combine adaptive RTO scheme with adaptive

packet type (i.e. DH5, DH3, DH1, DM5, DM3, packet type (i.e. DH5, DH3, DH1, DM5, DM3, DM1)DM1)

– Choose the best packet type for different BER Choose the best packet type for different BER rangesranges

– Implement the functionality to the Bluetooth Implement the functionality to the Bluetooth LC layerLC layer

– Optimal packet type can be selected Optimal packet type can be selected dynamicallydynamically

4040

ReferencesReferences

J.C. Haartsen, " J.C. Haartsen, " The The BluetoothBluetooth Radio System Radio System," IEEE Personal ," IEEE Personal Communications Magazine, Feb. 2000.Communications Magazine, Feb. 2000.

NS2 Simulator: NS2 Simulator: http://www.http://www.isiisi..eduedu//nsnamnsnam/ns//ns/ L.-J. Chen, R. Kapoor, K. Lee, M. Y. Sanadidi, M. Gerla, " L.-J. Chen, R. Kapoor, K. Lee, M. Y. Sanadidi, M. Gerla, "

Audio Streaming over Audio Streaming over BluetoothBluetooth: An Adaptive ARQ Timeout Approach: An Adaptive ARQ Timeout Approach,","

Reza Rejaie, Mark Handley, Deborah Estrin, "Reza Rejaie, Mark Handley, Deborah Estrin, " RAP: An End-to-end Rate-based Congestion Control Mechanism for RAP: An End-to-end Rate-based Congestion Control Mechanism for RealtimeRealtime Streams in the Internet Streams in the Internet," In Proceedings of IEEE INFOCOM ," In Proceedings of IEEE INFOCOM 1999. 1999.

G. Holland, and N. Vaidya,"G. Holland, and N. Vaidya," Analysis of TCP performance over mobile ad hoc networks Analysis of TCP performance over mobile ad hoc networks ," In ," In Proceedings of ACM Mobicom'99, Seattle, Washington, 1999. Proceedings of ACM Mobicom'99, Seattle, Washington, 1999.

Balk, D. Maggiorini, M. Gerla, and M. Y. Sanadidi, " Balk, D. Maggiorini, M. Gerla, and M. Y. Sanadidi, " Adaptive MPEG-4 Video Streaming with Bandwidth EstimationAdaptive MPEG-4 Video Streaming with Bandwidth Estimation, ", , ", UCLA. UCLA.

J. Tang, G. Morabito, I. F. Akyildiz, and M. Johnson, "J. Tang, G. Morabito, I. F. Akyildiz, and M. Johnson, "RCS: A Rate Control Scheme for Real-Time Traffic in Networks with HRCS: A Rate Control Scheme for Real-Time Traffic in Networks with High Bandwidth-Delay Products and High Bit Error Ratesigh Bandwidth-Delay Products and High Bit Error Rates," In Proceedings of Infocom 2001, Anchorage, AK, 2001. ," In Proceedings of Infocom 2001, Anchorage, AK, 2001.

audio streaming over bluetooth scatternet: using adaptive link layer

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