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 ), Bluetooth (IEEE ) and ZigBee (IEEE )
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 System1 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 3 4 5 6
time

6. Symmetric Throughput (Kbps) Asymmetric Throughput (Kbps)
Bluetooth – ACL Mode
DH : Data High Mode ACL: Asynchronous Connectionless Link DM : Data Medium Mode FEC: Forward Error Correction
Mode
FEC
Packet
Symmetric Throughput (Kbps)
Asymmetric Throughput (Kbps)
Size (bytes)
Length (slots)
DM1
yes 17 1
108.8
DM3
121 3
258.1
387.2
54.4
DM5
227 5
286.7
477.8
36.3
DH1 no 27
172.8
DH3
183
390.4
585.6
86.4
DH5
339
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
Networking Applications
TCP/UDP IP
BNEP (3 bytes)
L2CAP (4 bytes)
Bluetooth Baseband
Bluetooth Radio
Networking Applications
TCP/UDP IP
BNEP (3 bytes)
L2CAP (4 bytes)
Bluetooth Baseband
Bluetooth Radio

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
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
Iperf - UDP
469
129
415
328 82
Iperf - TCP
539
462
126
397
321 80
Unit: Kbps

10. Comparison – Average Capacity Estimation Time
Unit:mm’ss
Tool
Bluetooth Packet Type
DH5
DH3
DH1
DM5
DM3
DM1
AdHoc Probe
0’40
Pathrate
18’33
18’41
18’38
18’43
0’34
Iperf - UDP
0’12
0’17
0’13
0’22
Iperf - TCP
0’11
0’16
0’20

11. Analysis Maximum Data Throughput Probing Packet Size
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)
1500
1300
1100
900
DH5
640.0
693.3
586.7
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
Mode
Probing Packet Size (bytes)
1500
1300
1100
900
DH5
640.0
693.3
586.7
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

13. Analytic AdHoc Probe Results

14. TSProbe: Concept R=
k/1
k/2
k/3
k/4
k/5 -H
L-H
2L-H
3L-H
4L-H P
5L-H

15. TSProbe: Proposed Approach

16. Algorithm

17. Evaluations Simulations Experiments Initial Parameters NS-2 v2.28
UCBT v
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
Peak[0]
Peak[1]
Results
Theoretical C
P[0]
E[0]
C[0]
P[1]
E[1]
C[1] L H
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
585.51
DH1
1478
171.5
172.3
1451
172.7
173.5 27
172.89
172.8
DM5
1337
476.0
478.5
1113
475.3
478.2
224
478.35
477.8
DM3
1445
385.8
387.7
1324
385.3
387.3
121
387.50
387.2
DM1
1489
108.7
109.2
1472
108.9
109.5 17
109.33
108.8

20. Simulation Results – Multi-hop
Mode
Piconet (Kbps)
Scatternet (Kbps)
1 hop
2 hops
3 hops
4 hops
DH5
722.92
361.46
351.13
DH3
585.51
292.76
266.08
292.75
DH1
172.89
86.45
83.79
86.44
DM5
478.35
239.18
244.76
DM3
387.50
193.75
180.56
DM1
109.33
54.67
51.70
54.66

21. Experiment Results – Multi-hop
Mode
Piconet (Kbps)
Scatternet (Kbps)
1 hop
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

22. Internet Experiment Scenario
Bluetooth Connectivity
Internet
Laptop 2
Router
( )
Laptop 1
Router
( )( )
Workstation
Sender
(linux1.cise.ntu.edu.tw)

23. Robustness Experiments
Testbed Experiments
Internet Experiments
Mode
DH5
DH3
DH1
DM5
DM3
DM1
Success Rate
100%
80% -
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% -
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!