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.
Outline Introduction Overview of Bluetooth System Time-Slotted Path Capacity Estimation Comparison of Popular Capacity Estimation Tools Analysis TSProbe Proposed Approach Algorithm Evaluations Conclusion
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
Introduction Multimedia stream adaptation Rate control Overlay design QoS applications, etc.
Overview of Bluetooth System 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 3 4 5 6 time
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
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
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
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
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
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
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
Analytic AdHoc Probe Results
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
TSProbe: Proposed Approach
Algorithm
Evaluations Simulations Experiments Initial Parameters 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)
Evaluation – Bluetooth Topologies
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
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
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
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)
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
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
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