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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)
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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: [email protected]
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)