1. http://www.ifn.et.tu-dresden.de/tk/ 1 The Simulative Investigation of Zigbee/IEEE 802.15.4 By, Vaddina Prakash Rao Under the Guidance of, Dipl.-Ing. Dimitri Marandin (TUD) Dipl.-Ing. Falk Hofmann (ZMD AG) 13th December 2005 Thesis Defense on

2. http://www.ifn.et.tu-dresden.de/tk/ 2 1.Introduction to Zigbee 2.Simulation Environment 3.Performance Metrics 4.Performance Analysis 5.Adaptive Backoff Exponent (ABE) 6.Performance Analysis of ABE 7.Conclusions and Future Work Contents

3. http://www.ifn.et.tu-dresden.de/tk/ 3 Address Low Data Rate Applications Very Simple  Just about 14 PHY and 35 MAC Primitives Low Data Rate  868MHz – 20Kbps (Europe)  914MHz – 40Kbps (USA)  2.4GHz – 250Kbps (World Wide) Very Low Power Consumption  6 months – 2 years of battery use Low Cost  Avg. Module Cost: 5 – 6 Euro 1. Introduction to Zigbee

4. http://www.ifn.et.tu-dresden.de/tk/ 4 Device Classes  Full Function Device (FFD)  Reduced Function Device (RFD) Supported Modes  Beacon Enabled  Non beacon Network Topologies  Star  Peer-to-Peer 1.1 Zigbee Basics

5. http://www.ifn.et.tu-dresden.de/tk/ 5 FFD PAN-Coord (FFD) RFD Star Topology

6. http://www.ifn.et.tu-dresden.de/tk/ 6 FFD PAN-Coord (FFD) RFD Peer-to-Peer Topology

7. http://www.ifn.et.tu-dresden.de/tk/ 7 Beacon INACTIVE CAPCFP SD = aBaseSuperFrameDuration x 2 SO BI = aBaseSuperFrameDuration x 2 BO (GTS) BO/SO – Beacon/Superframe Order BI – Beacon Interval SD – Superframe Duration CAP – Contension Access Period CFP – Contension Free Period GTS – Guaranteed Time Slots 1.2 Superframe Structure

8. http://www.ifn.et.tu-dresden.de/tk/ 8 Network Device  Coordinator 01 PAN coordNode 1. Coord: Beacon Transmission 2. Node: Synchronizes to the Super frame structure 3. Node: Waits for its turn of transmission using CSMA-CA 4. Node: On its turn, transmits data FFD PAN-Coord (FFD) Legend DATA ACK 5. Coord: (Optional) Acknowledges the data reception 1.3 Data Transmission

9. http://www.ifn.et.tu-dresden.de/tk/ 9 SimulatorNS-2 Zigbee Parameters Frequency Band 868Mhz Scan Channels 0, 1 and 2 Transmitting Power (Pt_)1mW RXThresh_ -97dBm (1.9952e -13 W) CSThresh_ -97dBm (1.9952e -13 W) CPThresh_ 10 Antenna Height0.0864m Physical Parameters Propagation ModelTwoRay Ground Antenna TypeOmni Antenna 2. Simulation Environment

10. http://www.ifn.et.tu-dresden.de/tk/ 10 Traffic Parameters Traffic Type CBR (Constant Bit Rate) Number of Flows 8 Packet Size70 Bytes Traffic Directionnode  Coordinator Queue Parameters Queue TypeDrop Tail Queue Length150 packets General Simulation Time 1000 Secs Initial Energy13000 Joules Number of Nodes15 Confidence Intervals95%

11. http://www.ifn.et.tu-dresden.de/tk/ 11 Throughput Total data bits received by all the nodes per second. Average Delay Flight time of a data packet to reach the destination. Delivery Ratio Percentage of successfully received packets. Energy Consumed Energy consumed to achieve throughput. 3. Performance Metrics

12. http://www.ifn.et.tu-dresden.de/tk/ 12 4. Performance Analysis 4.1 Throughput Analysis

13. http://www.ifn.et.tu-dresden.de/tk/ 13 4.2 Delivery Ratio

14. http://www.ifn.et.tu-dresden.de/tk/ 14 4.3 Energy Consumption

15. http://www.ifn.et.tu-dresden.de/tk/ 15 4.4 Packet Drops - Link Quality Indication

16. http://www.ifn.et.tu-dresden.de/tk/ 16 4.5. Backoff Exponent Management Backoff Exponent (BE): Determines number of backoff periods (= 2 BE -1) the device waits before checking the channel The Problem !! To conserve energy Zigbee uses very small BEs. => devices tend to choose identical backoff exponents (identical backoff) periods. => frequent collisions

17. http://www.ifn.et.tu-dresden.de/tk/ 17 5. Adaptive Backoff Exponent (ABE) Coord calculates contribution by each node 0 1 7 6 5 4 3 2 8 5, 6, 7 and 8 transmit to Coordinator Beacon enabled PAN End of Analyzing Cycle !! 27 31 35 39 28 32 36 40 29 33 37 41 30 34 38 42 31 35 39 43 32 36 40 44 33 37 41 45 68576857 node Pkts Recv Start of Analyzing Cycle 34 38 42 46

18. http://www.ifn.et.tu-dresden.de/tk/ 18 6 46 Coordinator has Information about each nodes contribution to network traffic At the coordinator Node Contribution to n/w traffic (num of pkts) 57 38 34 Arranging their contribution in ascending order Arranging into Groups 8 42 5 38 6 46 Group-1Group-2 Check if it is time to implement ABE - ≥ PKT_DIFFERENCE 8 42 7 34 5 38 6 4246 8 7 34 PKT_DIFFERENCE = 7

19. http://www.ifn.et.tu-dresden.de/tk/ 19 Beacon Construction Coordinator decides Decrement BE of 5, 7 Increment BE of 6, 8 5 8 During the beacon construction... Inserting the number of increments and decrements Inserting the addresses 76 At the coordinator 5 8 7 6

20. http://www.ifn.et.tu-dresden.de/tk/ 20 At the Nodes 58 Receive the beaconRead the ABE fields If their address listed, change BE macMinBE --macMinBE ++ 76

21. http://www.ifn.et.tu-dresden.de/tk/ 21 6. Performance Analysis of ABE

22. http://www.ifn.et.tu-dresden.de/tk/ 22 Applicability of Zigbee as an ideal automation technology for low data rate applications is investigated General Performance Analysis Maximum achievable data bandwidth = 5.3Kbps Achievable Data Bandwidth @ 99% delivery ratio = 5.25kbps A device transmitting @ 10.07 Kbytes/day = 4 months Performance Analysis with ABE Maximum achievable data bandwidth = 6.73kbps 27% Improvement of maximum throughput Achievable Data Bandwidth @ 99% delivery ratio = 6.554kbps 25% Improvement of maximum throughput @ 99% delivery ratio 7. Conclusions

23. http://www.ifn.et.tu-dresden.de/tk/ 23 Future Work Development of the software modules for the GTS implementation to investigate topics like  efficient bandwidth utilization with GTS and CAP,  reliable data transfer under these conditions Development of software modules for accurate energy consumption analysis Routing in complex mesh topologies Applying the Adaptive backoff exponent algorithm  At congestion situations for 2.4Ghz.  For mixed traffic scenarios

24. http://www.ifn.et.tu-dresden.de/tk/ 24 Thank you !!