presentation of bluetooth activities of aalborg university at blip systems

Slide 1 of 21

Presentation of Bluetooth Activities of Aalborg University at BLIP Systems

Slide 2 of 21

BLIP Meeting - Agenda

• Agenda:– Preliminary Results of TCP Performance over

Bluetooth (Dennis Dungs, ca. 30 min)

– Location Information in Bluetooth (Joao Figueiras, ca. 30 min)

– Scatternet Formation (Istvan Kovacs, ca. 30 min)

– Set-up of experimental Bluetooth network at Aalborg University(who??, 10 min)

– Bluetooth simulation tools (who??, 10 min)

Slide 3 of 21

Implementation and Evaluation of a Performance Enhancing Proxy for Wireless

TCP

Master Thesis Project (Sep 03 – April 04)

Dennis DungsTechnical University Munich, Germany

Aalborg University, Denmark

March 2004

Supervised byHans-Peter Schwefel

Aalborg University, Denmark

Slide 4 of 21

Agenda

• Goal and steps of this project

• Considered Scenarios in the project

• Short Reminder: TCP

• Evaluation of Bluetooth Performance– UDP in Single MN AP Scenario– TCP in Single MN AP Scenario

• Conclusions

Slide 5 of 21

Goal of this project

• Goal:– Identify TCP performance lacks in wireless scenarios– Evaluate performance capabilites of a TCP Proxy

• Steps– Getting familiar with concepts of TCP– Research about common TCP implementations– Describing wireless scenarios– Analyzing TCP performance and Identifying TCP

performance lacks in wireless scenarios– Designing and Implementing a TCP Proxy– Evaluation of Scenarios using the TCP Proxy

Slide 6 of 21

Considered Scenarios

• Definition:„A Scenario consists of a description of the network infrastructure, mobility model and traffic model.“

Proxy

Server

Wired Network

MobileHost

Wirelesssupporting Network

• Network Infrastructure:– Access Technology– Proxy Location– Sender / Receiver Location– Network configuration

• Mobility Model– Fixed position– Handover to same/different subnet– Handover to new access technology

• Traffic Model– Size of transmitted data– Used bandwith– Single-/Multi-User– Cross-traffic– Constant / Burst Traffic

Slide 7 of 21

Short Reminder - TCP• Goals of TCP:

– Connection oriented, full duplex protocol– Multiplexing of IP-datagram service (Ports)– In-order data transfer (Sequence Numbers)– Reliable data transfer (Acknowledgements)– Prevent Receiver from flooding (Receiver Advertised Window)– Prevent intermediate systems from flooding (Congestion Control

Algorithm)

• Congestion Control– Congestion Window: Number of bytes, that can be send in one

RTT without congestion– Dynamically adjusted until congestion indicated via DUPACKs or

timeouts– Exponential increase per RTT to reach maximum throughput

(slow-start)– Continuous probing of maximum available bandwith via linear

increase/ multiplicative decrease per RTT

Slide 8 of 21

Evaluation

Slide 9 of 21

Evaluation – Measurement Procedure

• IPerf – Setup a UDP/TCP connection from sender to receiver– Send data from sender to receiver at maximum bandwidth (TCP)

or given bandwidth (UDP)

• Ethereal – Trace Ethernet packets at sender and receiver in real-time into a

file– Traces arrival times of packets t(n) and contents of Ethernet

packets

• TCPTrace– Generate TCP Statistics offline

• Matlab– Generating UDP Statistics offline– Calculating statistical parameters

• GNUPlot– Visualizing TCP Statistics (RTT Graphs, Throughput Graphs)

Slide 10 of 21

Evaluation - Metrics

• Instantaneous Throughput

• Instantaneous Averaged Throughput

• Transmission Throughput

• Round-Trip-Times (RTT)

const.k 1),-(i*k n ,)( 1,

nkn

kn

nll

AvgInst tt

epayloadsizi

1

1)(tt

epayloadsizn

n

n

ii

ontransmissi

1

)(

nn

nInst tt

epayloadsizn

Slide 11 of 21

Single Connection over Bluetooth - Scenario

10.10.1.X

Tokyo DelftAalborg

China

Mobile Node

Toronto

Server

10.10.3.254

8 MBit/s 8 MBit/s

100 MBit/s

100 MBit/s100 MBit/s

Shanghai

100 MBit/s

Fixed Host Mobile HostRouter Switch BT AP

Legend:

Network Setup: • Scenario Parameters:– MN: 2.6 GHz-P4 512MB

RAM, WinXP, Belkin Class2 BT USB Adapter

– AP: BlipNet BlipNode L1– Supposed Master: AP– Supposed Slave: Mobile Node– Application Profile: PAN– Distance AP->MN: 1m– Server: PPro 166Mhz, 32MB

RAM, running Redhat 7.3– Sending duration: 30sec– UDP payloadsize: 1470 bytes– UDP Bandwith: 700kBit/s

(Application Layer Bandwith)– TCP receiver buffer: 8 kBytes

Downstream

Slide 12 of 21

Single UDP Connection over Bluetooth

Slide 13 of 21

Single UDP Connection over Bluetooth

Slide 14 of 21

Single TCP Connection over Bluetooth

Slide 15 of 21

Single TCP Connection over Bluetooth

Slide 16 of 21

Single TCP Connection over Bluetooth

• Possible Reasons for throughput jumps– Traffic in low-bandwidth direction (Routers)

• Packet Scheduler has to send more data• Adjusting to „more symmetric“ bandwidth• Flow Control on Baseband

– Interference• Channel quality driven data rate change (CQDDR)

Slide 17 of 21

Additional Results

• Upstream (Slave->Master) gains always higher throughput than downstream

• Adhoc – Scenario:– Same throughput jumps (UDP & TCP) as in

AP-scenario, but less likely– Higher average throughput

• No significant differences between WinXP (WidComm-Stack) and Linux (BlueZ-Stack)

Slide 18 of 21

Conclusions - Questions

• Conclusion:– Many factors could cause the throughput-

dropdown– Difficult to analyze TCP performance lacks, if

underlying behaviour unclear– To get deeper understandings, packet trace

tool for Baseband is needed

Slide 19 of 21

References

• Project WebSite: http://kom.aau.dk/~dennis/

• IPLab WebSite: http://kom.aau.dk/iplab/

• RFCs : RFC791 (IP), RFC793 (TCP), a.o.http://www.ietf.org/

• Bluetooth Specificationhttp://www.bluetooth.org/

• eMail: dennis@kom.aau.dk

Slide 20 of 21

Thanks for listening!

Any Questions?

Yes, i have some...

Slide 21 of 21

Questions

• How to figure out, which Bluetooth device is master, which is slave (role switching)?

• How to figure out, which packet types are used (DM, DF, AUX) ?

• How to figure out, if master/slave uses „Channel quality driven data rate change” and when it affects the channel

• How to figure out, how “Flow Control” on baseband level is influencing the throughput?

=> Is it possible to trace packets at Baseband level?

Slide 22 of 21

Backup

Slide 23 of 21

Adhoc UDP Connection over Bluetooth

• Scenario Parameters– MN 1: 2.6 GHz-P4 512MB

RAM, WinXP, Belkin Class2 BT USB Adapter

– MN 2: 266MHz-P 64MB RAM, WinXP, Belkin Class2 BT USB Adapter

– Supposed Master: MN 1– Supposed Slave: MN 2– Application Profile: PAN– Distance MN1->MN2: 1m– Sending duration: 10sec– UDP payload-size: 1470 bytes– UDP Bandwith: 700kBit/s

(Application Layer Bandwith)

Mobile Node 1(supposed Master)

Mobile Node 2(supposed Slave)

UDP Downstream

UDP Upstream

Slide 24 of 21

Adhoc UDP Connection over Bluetooth - Downstream

Slide 25 of 21

Adhoc UDP Connection over Bluetooth - Upstream

Slide 26 of 21

Adhoc UDP Connection over Bluetooth - Comparison

Slide 27 of 21

Adhoc TCP Connection over Bluetooth

• Scenario Parameters– MN 1: 2.6 GHz-P4 512MB

RAM, WinXP, Belkin Class2 BT USB Adapter

– MN 2: 266MHz-P 64MB RAM, WinXP, Belkin Class2 BT USB Adapter

– Supposed Master: MN 1– Supposed Slave: MN 2– Application Profile: PAN– Distance MN1->MN2: 1m– Sending duration: 10sec– Standard WinXP TCP

Implementation– TCP Window Size: 8kByte

Mobile Node 1(supposed Master)

Mobile Node 2(supposed Slave)

TCP Downstream

TCP Upstream

Slide 28 of 21

Adhoc TCP Connection over Bluetooth – Comparison US/DS

Slide 29 of 21

Adhoc TCP Connection over Bluetooth

Slide 30 of 21

Current IPLab network architectureIP LAB: Current Architecture

Delft

Internet

Toronto

Frankfurt

Shanghai

Sydney Dhaka

Tokyo

San Francisco 130.225.51.6

10.10.1.210.10.2.2

10.10.2.1 10.10.1.1

Aalborg

10.10.2.254

Istanbul10.10.4.2

10.10.1.254

Shanghai

10.10.3.254

10.10.254.254

Toronto10.10.3.1

GPRS Network

Slide 31 of 21

Single TCP Connection over Bluetooth - Scenario

10.10.1.X

Tokyo DelftAalborg

China

Mobile Node

Toronto

Server

10.10.3.254

8 MBit/s 8 MBit/s

100 MBit/s

100 MBit/s100 MBit/s

Shanghai

100 MBit/s

Fixed Host Mobile HostRouter Switch BT AP

Legend:

Network Setup: • Scenario Parameters:– MN: 2.6 GHz-P4 512MB

RAM, SuSE Linux 9.0 (Kernel 2.4.21-166), BlueZ Stack (Lib 2.5, SDP 1.5, PAN 1.1)

– AP: BlipNet BlipNode L1– Master: AP– Slave: Mobile Node– Application Profile: PAN– Distance AP->MN: 1m– Server: PPro 166Mhz, 32MB

RAM, running Redhat 7.3– Sending duration: 30sec– Standard TCP

Implementations– TCP Window Size: 8kByte

Slide 32 of 21

Single TCP Connection over Bluetooth (Linux)