1(48) An Analysis of the Throughput of Packet Radio Networks André Stranne Licentiate thesis presentation Lund, 16/5 – 2003 André Stranne Licentiate thesis presentation Lund, 16/5 – 2003

2(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

3(48) Introduction and background An Analysis of the Throughput of Packet Radio Networks

4(48) An Analysis of the Throughput of Packet Radio Networks Data communications Wireline Wireless Radio Fixed phone ADSL Ethernet Fixed phone ADSL Ethernet GSM Bluetooth 3G GSM Bluetooth 3G Internet IR Sound

5(48) An Analysis of the Throughput of Packet Radio Networks Radio networks Circuit switched Packet switched Phone calls GSM (3G) GSM (3G) Internet data Bluetooth GPRS (3G) Bluetooth GPRS (3G)

6(48) An Analysis of the Throughput of Packet Radio Networks ? OK Throughput

7(48) An Analysis of the Throughput of Packet Radio Networks - What data rates can be expected in packet radio networks?

8(48) Analysis: How to do it? Analyze real packet radio networks –Realistic but not very convenient Create mathematical models of packet radio networks Analyze real packet radio networks –Realistic but not very convenient Create mathematical models of packet radio networks

9(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

10(48) Main features Networks, units Packet transmissions Packet-based slow frequency hopping Different packet lengths Networks, units Packet transmissions Packet-based slow frequency hopping Different packet lengths

11(48) System model System Networks Units System Networks Units Interference

12(48) Packet transmissions Frequency channels Packet-based frequency hopping Frequency channels Packet-based frequency hopping

13(48) Performance measure Throughput = achieved data rate Network Transmitted data Lost data Throughput

14(48) Packet reception models What is the cause of packet losses in the networks? –Packet collision analysis: –Interfering energy analysis: What is the cause of packet losses in the networks? –Packet collision analysis: –Interfering energy analysis: Collisions Interfering energy Interfering energy

15(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

16(48) Collision analysis Packet reception model –Packet losses from packet collisions Packet reception model –Packet losses from packet collisions ?

17(48) Collision analysis Packet reception model –Packet losses from packet collisions Packet reception model –Packet losses from packet collisions

18(48) Collision analysis Probability of collision? Probability of successful packet reception? Throughput? Probability of collision? Probability of successful packet reception? Throughput?

19(48) Calculation outline Calculate how probable n collisions are with packets transmitted from a single interferer j, Hard to find that expression Details in the thesis Hard to find that expression Details in the thesis

20(48) Calculation outline Calculate how probable n collisions are with packets transmitted by all interferers Assumption: independent packet transmissions Convolutions of PDFs (probability distribution functions)

21(48) Calculation outline Sum the probabilities for the number of collisions that can be tolerated for successful packet reception If no collisions can be tolerated: Sum the probabilities for the number of collisions that can be tolerated for successful packet reception If no collisions can be tolerated:

22(48) Bluetooth example System of Bluetooth ”piconets” 79 frequency channels System of Bluetooth ”piconets” 79 frequency channels 625 μs

23(48) Bluetooth example Single interferer! 79 channels Low collision probability! No collisions 2 collisions1 collision Prob. of number of collisions from single interferer

24(48) Bluetooth example Medium size packet type 20 interferers40 interferers60 interferers 80 interferers 100 interferers All interferers! Prob. of total number of collisions

25(48) Bluetooth example More interferers More collisions More lost packets Reduced data rate No interferers 26 Network throughput 50 %

26(48) Bluetooth example Increasing system throughput Decreasing system throughput Maximum system throughput Total throughput for all piconets in the system System throughput

27(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

28(48) Energy analysis Collision-based packet reception model no collision collision

29(48) Energy analysis New packet reception model –More detailed –The collision analysis does not account for the duration of the packet overlaps in the collisions the strength of the received interfering signals –Interfering energy New packet reception model –More detailed –The collision analysis does not account for the duration of the packet overlaps in the collisions the strength of the received interfering signals –Interfering energy

30(48) Energy analysis Interfering energy Time Single frequency channel

31(48) Energy analysis Interfering energy Time 1 Length of overlap Signal strength

32(48) Energy analysis Interfering energy Time 1 2

33(48) Energy analysis Interfering energy Time 1 2 3

34(48) Energy analysis Interfering energy

35(48) Calculation outline Basically the same as for the collision analysis Variables for number of collisions Variables for number of collisions Variables for amount of interfering energy Variables for amount of interfering energy

36(48) Bluetooth example Link budget

37(48) Bluetooth example Distance between interferers and reference nodes Increasing interference Network throughput

38(48) Bluetooth example System throughput

39(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

40(48) Complexity issues Exact expressions complicated Simple approximations needed –For the collision-based analysis, we have such an approximation –Approximation of energy-based analysis is beyond the scope of this thesis Exact expressions complicated Simple approximations needed –For the collision-based analysis, we have such an approximation –Approximation of energy-based analysis is beyond the scope of this thesis

41(48) Full expression / approximation Approximation Accurate enough?

42(48) Approximation error (Bluetooth example) Bluetooth 79 channels 10 channels30 channels

43(48) Outline Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary Introduction and background System model Packet collision analysis Interfering energy analysis Approximations Summary

44(48) Contributions Probabilistic framework for analysis of PRNs that transmit packets of different lengths Exact expressions for the throughput Approximate expression which can be used for strongly interfering networks Probabilistic framework for analysis of PRNs that transmit packets of different lengths Exact expressions for the throughput Approximate expression which can be used for strongly interfering networks

45(48) Publications F. Florén, A. Stranne and O. Edfors, Analysis of Slow Frequency Hopping Networks, NRS 01, Sweden, 2001 F. Florén, A. Stranne, O. Edfors and B.-A. Molin, Throughput Analysis of Strongly Interfering Slow Frequency-Hopping Wireless Networks, VTC Spring 2001, Greece, 2001 A. Stranne, F. Florén and O. Edfors, Evaluating a Performance Analysis of Slow FH Systems by Simulations, RVK 02, Sweden, 2002 A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Throughput of IEEE FHSS Networks in the Presence of Strongly Interfering Bluetooth Networks, PIMRC 2002, Portugal, 2002 F. Florén, A. Stranne and O. Edfors, Analysis of Slow Frequency Hopping Networks, NRS 01, Sweden, 2001 F. Florén, A. Stranne, O. Edfors and B.-A. Molin, Throughput Analysis of Strongly Interfering Slow Frequency-Hopping Wireless Networks, VTC Spring 2001, Greece, 2001 A. Stranne, F. Florén and O. Edfors, Evaluating a Performance Analysis of Slow FH Systems by Simulations, RVK 02, Sweden, 2002 A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Throughput of IEEE FHSS Networks in the Presence of Strongly Interfering Bluetooth Networks, PIMRC 2002, Portugal, 2002

46(48) Publications A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Throughput of Strongly Interfering Slow Frequency-Hopping Networks, submitted to IEEE Transactions on Communications, 2003 A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Analysis of Strongly Interfering Slow Frequency-Hopping Systems, Technical Report, Department of Electroscience, Lund University, 2003 A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Throughput of Strongly Interfering Slow Frequency-Hopping Networks, submitted to IEEE Transactions on Communications, 2003 A. Stranne, F. Florén, O. Edfors and B.-A. Molin, Analysis of Strongly Interfering Slow Frequency-Hopping Systems, Technical Report, Department of Electroscience, Lund University, 2003

47(48) Future work Approximations Development of system model Applications of the results Approximations Development of system model Applications of the results

48(48) Special thanks to