Ling-Jyh Chen1, Chih-Wei Sung2,

1
Path Capacity Estimation in Time-Slotted Wireless
Networks

• Ling-Jyh Chen1, Chih-Wei Sung2,
• Hao-Hsiang Hung1, Tony Sun3, Cheng-Fu Chou2
• 1Academia Sinica
• 2National Taiwan University
• 3PacketMotion Inc.

2
Outline

• Introduction
• Overview of Bluetooth System
• Time-Slotted Path Capacity Estimation
• Comparison of Popular Capacity Estimation Tools
• Analysis
• TSProbe
• Proposed Approach
• Algorithm
• Evaluations
• Conclusion

3
Introduction

• Knowing the end-to-end path capacity is important
  for wireless applications
• Time-slotted wireless techniques are increasingly
  popular
• WiMAX (IEEE 802.16), Bluetooth (IEEE 802.15.1)
  and ZigBee (IEEE 802.15.4)
• An effective path capacity estimation tool in
  time-slotted wireless systems is still lacking

4
Introduction

• Multimedia stream adaptation
• Rate control
• Overlay design
• QoS applications, etc.

5
Overview of Bluetooth System
0
1
2
3
4
5
master
slave 1
slave 2
625 µ sec
1600 hops/sec
Data Packet
ACK Packet
DH1/DM1
DH3/DM3
DH5/DM5
1
2
4
3
5
6
time
6
Bluetooth ACL Mode

• DH Data High Mode
  ACL
  Asynchronous Connectionless Link
• DM Data Medium Mode
  FEC Forward
  Error Correction

Mode FEC Packet Packet SymmetricThroughput(Kbps) AsymmetricThroughput(Kbps) AsymmetricThroughput(Kbps)
Mode FEC Size (bytes) Length(slots) SymmetricThroughput(Kbps) AsymmetricThroughput(Kbps) AsymmetricThroughput(Kbps)
DM1 yes 17 1 108.8 108.8 108.8
DM3 yes 121 3 258.1 387.2 54.4
DM5 yes 227 5 286.7 477.8 36.3
DH1 no 27 1 172.8 172.8 172.8
DH3 no 183 3 390.4 585.6 86.4
DH5 no 339 5 433.9 723.2 57.6
7
Overview of Bluetooth System

• Sender
  Receiver
• BNEP Bluetooth Network Encapsulation Protocol
• L2CAP Link Layer Control and Adaptation Layer
  Protocol

8
Evaluation of Capacity Estimation Tools

• The setting of capacity estimation tools
• AdHoc Probe
• Probing packet size 1500 bytes
• 5 probes per second
• Pathrate and Iperf
• Default setting
• One-hop Bluetooth testbed
• Average of results of 10 experiment runs

9
Comparison Average Link Capacity Estimates
Tool Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type
Tool DH5 DH3 DH1 DM5 DM3 DM1
Theoretical 723.2 585.6 172.8 477.8 387.2 108.8
AdHoc Probe 643 541 138 459 370 84
Pathrate 608 537 137 432 360 84
Iperf - UDP 541 469 129 415 328 82
Iperf - TCP 539 462 126 397 321 80

• 
  Unit Kbps

10
Comparison Average Capacity Estimation Time

• 
  
  
• 
  
  Unitmmss

Tool Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type Bluetooth Packet Type
Tool DH5 DH3 DH1 DM5 DM3 DM1
AdHoc Probe 040 040 040 040 040 040
Pathrate 1833 1841 1838 1841 1843 034
Iperf - UDP 012 012 017 013 013 022
Iperf - TCP 011 012 016 012 012 020
11
Analysis
Maximum Data Throughput

• The effective link capacity is dependent on the
  employed packet size

Probing Packet Size
Baseband Packet Size
Capacity Estimation
Bluetooth Stack Header
12
Analysis AdHoc Probe Estimates

• Analytical Results
  Simulation Results
• Unit
  Kbps
  Unit Kbps

Mode Probing Packet Size (bytes) Probing Packet Size (bytes) Probing Packet Size (bytes) Probing Packet Size (bytes)
Mode 1500 1300 1100 900
DH5 640.0 693.3 586.7 640.0
DH3 533.3 520.0 502.9 576.0
DH1 171.4 169.8 171.7 169.4
DM5 457.1 462.2 469.3 383.9
DM3 369.2 378.2 352.0 360.0
DM1 107.9 108.1 106.7 106.7
Mode Probing Packet Size (bytes) Probing Packet Size (bytes) Probing Packet Size (bytes) Probing Packet Size (bytes)
Mode 1500 1300 1100 900
DH5 640.0 693.3 586.7 640.0
DH3 533.3 520.0 502.9 576.0
DH1 171.4 169.8 171.7 169.4
DM5 457.1 462.2 469.3 383.9
DM3 369.2 378.2 352.0 360.0
DM1 107.9 108.1 106.7 106.7
13
Analytic AdHoc Probe Results
14
TSProbe Concept
k/3
k/5
k/4
k/2
k/1
R
P
L-H
2L-H
3L-H
4L-H
-H
0
5L-H
15
TSProbe Proposed Approach
P1
P0
16
Algorithm

17
Evaluations

• Simulations
• NS-2 v2.28
• UCBT v0.9.8.2
• Experiments
• Packet-pairs 100 samples, 4 packet-pairs per
  second
• 10 TSProbe runs on each link mode
• Initial Parameters
• MTU 1500 bytes
• p_start 1500 (bytes)
• Init_range 64 (bytes)

18
Evaluation Bluetooth Topologies
19
Simulation Results One-hop
Mode Peak0 Peak0 Peak0 Peak1 Peak1 Peak1 Results Results Results Theoretical C
Mode P0 E0 C0 P1 E1 C1 L H C Theoretical C
DH5 1349 719.0 722.8 1010 718.1 723.1 339 7 722.92 723.2
DH3 1457 583.8 585.6 1274 582.2 585.4 183 7 585.51 585.6
DH1 1478 171.5 172.3 1451 172.7 173.5 27 7 172.89 172.8
DM5 1337 476.0 478.5 1113 475.3 478.2 224 7 478.35 477.8
DM3 1445 385.8 387.7 1324 385.3 387.3 121 7 387.50 387.2
DM1 1489 108.7 109.2 1472 108.9 109.5 17 7 109.33 108.8
20
Simulation Results Multi-hop
Mode Piconet (Kbps) Piconet (Kbps) Scatternet (Kbps) Scatternet (Kbps) Scatternet (Kbps)
Mode 1 hop 2 hops 2 hops 3 hops 4 hops
DH5 722.92 361.46 351.13 361.46 361.46
DH3 585.51 292.76 266.08 292.75 292.75
DH1 172.89 86.45 83.79 86.44 86.44
DM5 478.35 239.18 244.76 239.18 239.18
DM3 387.50 193.75 180.56 193.75 193.75
DM1 109.33 54.67 51.70 54.66 54.66
21
Experiment Results Multi-hop
Mode Piconet (Kbps) Piconet (Kbps) Scatternet (Kbps) Scatternet (Kbps) Scatternet (Kbps)
Mode 1 hop 2 hops 2 hops 3 hops 4 hops
DH5 726.03 343.69 308.91 271.82 246.91
DH3 594.02 282.19 262.08 237.61 217.62
DH1 139.61 78.47 82.93 67.99 29.13
DM5 479.39 228.72 237.32 165.42 158.68
DM3 387.56 161.86 191.71 150.12 149.85
DM1 X X X X X
22
Internet Experiment Scenario
Bluetooth Connectivity
Internet
Laptop 2 Router (10.0.0.2)
Laptop 1 Router (218.161.124.93)(10.0.0.1)
Workstation Sender (linux1.cise.ntu.edu.tw)
23
Robustness Experiments

• Testbed Experiments
• 
  Internet Experiments

Mode DH5 DH3 DH1 DM5 DM3 DM1
Success Rate 100 100 80 100 100 -
Time Consumption 15 min. 12 min. 10 min. 14 min. 13 min. X
Minimum Steps 27 24 20 26 23 x
Mode DH5 DH3 DH1 DM5 DM3 DM1
Success Rate 100 80 10 90 80 -
Time Consumption 17 min. 14 min. 10 min. 18 min. 12 min. X
Minimum Steps 27 24 20 26 23 x
24
Conclusion

• An analytical model presents the relationship
  between the link capacity estimation and channel
  utilization
• TSProbe can adapt to the properties of link layer
  in time-slotted systems for estimating the
  end-to-end capacity
• TSProbe is an accurate, robust and reliable
  capacity estimation tool
• This study is also applicable to other
  time-slotted systems

25

• Thanks for your patience!
• http//www.iis.sinica.edu.tw/cclljj/
• http//nrl.iis.sinica.edu.tw/