2. WCNC 2008 March 31 - April 3 Las Vegas Department of Information Engineering University of Padova, ITALY Throughput and Energy Efficiency of Bluetooth v2 + EDR in Fading Channels A note on the use of these ppt slides: We’re making these slides freely available to all, hoping they might be of use for researchers and/or students. They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. In return for use, we only ask the following: If you use these slides (e.g., in a class, presentations, talks and so on) in substantially unaltered form, that you mention their source. If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and put a link to the authors webpage: www.dei.unipd.it/~zanella Thanks and enjoy! A note on the use of these ppt slides: We’re making these slides freely available to all, hoping they might be of use for researchers and/or students. They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. In return for use, we only ask the following: If you use these slides (e.g., in a class, presentations, talks and so on) in substantially unaltered form, that you mention their source. If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and put a link to the authors webpage: www.dei.unipd.it/~zanella Thanks and enjoy!

3. WCNC 2008 March 31 - April 3 Las Vegas Department of Information Engineering University of Padova, ITALY Throughput and Energy Efficiency of Bluetooth v2 + EDR in Fading Channels {andrea.zanella, michele.zorzi}@dei.unipd.it Andrea Zanella, Michele Zorzi WCNC 2008 Special Interest Group on NEtworking & Telecommunications Speaker: Marco Miozzo

4. WCNC 2008 March 31 - April 3 Las Vegas Motivations  Bluetooth was designed to be integrated in portable battery driven electronic devices  Energy Saving is a key issue!  Units periodically scan radio channel for valid packets  Scanning takes just the time for a valid packet to be recognized  Units that are not addressed by any valid packet are active for less than 10% of the time  WPAN market is expanding and it aims at becoming the standard the facto for short range communications  High Throughput is very welcome!  Bluetooth v2.0 + EDR (Enhanced Data Rate) promise bit rates up to 3 Mbps and faster node connections

5. WCNC 2008 March 31 - April 3 Las Vegas Aims of the work  Questions:  Are the Bluetooth promises maintained?  What’s the energy efficiency & throughput achieved by EDR frame formats in realistic channels?  Which units shall be the Master in point-to-point connections?  Answer  Well, in most cases, we cannot provide univocal answers… …but we can offer a mathematical model to decide case by case!

6. WCNC 2008 March 31 - April 3 Las Vegas Basic ingredients  Define realistic radio channel model  Flat Rice-modelled fading channel  BER curves for different modulations taken from the literature  Capture system dynamic by means of a Finite State Markov Chain (FSMC)  State transitions driven by packet reception events  Define appropriate reward functions  Data, Energy, Time  Apply renewal reward theorem to get system performance  Throughput, energy efficiency, energy balancing, …

7. WCNC 2008 March 31 - April 3 Las Vegas What standard says… Bluetooth reception mechanism

8. WCNC 2008 March 31 - April 3 Las Vegas Physical layer  Basic Rate: 1Mbps  GFSK [13]  EDR2: 2Mbps   /4-DQPSK [14]  EDR3  8DPSK [15] [13] J. S. Roh, “Performance analysis and evaluation of Bluetooth networks in wireless channel environment,” ICSNC’06 [14] L. E. MillerandJ. S. Lee, “BER Expressions for Differentially Detected π/4 DQPSK Modulation,” IEEE TRANSACTIONS ON COMMUNICATIONS, vol. 46, no. 1, pp. 71–81, January1998. [15] N. Benvenuto and C. Giovanni, Algorithms for Communications Systems and their Applications. Wiley, 2002.

9. WCNC 2008 March 31 - April 3 Las Vegas 0.22 ms T slot =0.625 ms T Dxn =nT slot ACHEAD PAYL GFSK 0.22 ms T slot =0.625 ms T jDxn = nT slot ACHEAD PAYL GFSK GUARDSYNC EDR Trailer DPSK Baseband frame formats BR EDR

10. WCNC 2008 March 31 - April 3 Las Vegas Retransmissions MASTER SLAVE ABBBB GFH NAK ACK  Automatic Retransmission Query (ARQ):  Each data packet is transmitted and retransmitted until positive acknowledge is returned by the destination  Negative acknowledgement is implicitly assumed! Errors on return packet determine transmission of duplicate packets (DUPCK) Slave filters out DUPCKs by checking their sequence number never  Slave does never transmit DUPCKs! Slave can transmit when it receives a Master packet Master packet piggy-backs the ACK/NACK for previous Slave transmission Slave retransmits only when needed! H B A X BX DPCK

11. WCNC 2008 March 31 - April 3 Las Vegas Mathematical Analysis System Model

12. WCNC 2008 March 31 - April 3 Las Vegas Mathematical Model  Normal State (N)  Master transmits packets that have never been correctly received by the slave  Duplicate State (D)  Master transmits duplicate packets (DUPCKs)  The steady-state probabilities are, then,  State transition probabilities depend on the reception events…

13. WCNC 2008 March 31 - April 3 Las Vegas Reception Event Index Slaves tx Master tx Reception events  Reception events  Ds = Data successful AC ok, HEAD ok, CRC ok  Df = Data failure AC ok, HEAD ok, CRC error  Hf = HEAD failure AC ok, HEAD error  Af = AC failure AC error  MC state transitions  N = enter Normal State Master tx non-duplicate packets  D = enter Duplicate State Master tx DUPCKs  X = loop step Return in the same state

14. WCNC 2008 March 31 - April 3 Las Vegas Reward Functions  For each state j we define the following reward functions  T j = Average amount of time spent in state j  D j (x) = Average amount of data delivered by unit x  {M,S}  W j (x) = Average amount of energy consumed by unit x  {M,S}  The average amount of reward earned in state j is given by  Performance indexes  Energy Efficiency:   Goodput: G

15. WCNC 2008 March 31 - April 3 Las Vegas Time reward ( T ) Master Frame Slave Frame n+m n+1 Empty slot

16. WCNC 2008 March 31 - April 3 Las Vegas Data reward ( D ) Master’s DataSlave’s Data D xn   D ym D xn   --- No Useful Data --- D ym

17. WCNC 2008 March 31 - April 3 Las Vegas Master energy reward ( W (M) ) Tx powerRx PowerSx power

18. WCNC 2008 March 31 - April 3 Las Vegas Slave energy reward ( W )  Slave’ energy reward resembles mater’ one except that, in D state, Slave does not listen for the PAYL field of recognized downlink packet since it has been already correctly received!

19. WCNC 2008 March 31 - April 3 Las Vegas Performance Analysis Results

20. WCNC 2008 March 31 - April 3 Las Vegas AWGN

21. WCNC 2008 March 31 - April 3 Las Vegas Rayleigh

22. WCNC 2008 March 31 - April 3 Las Vegas Conclusions  Main Contribution  mathematical framework for performance evaluation of Bluetooth EDR links  Results  3DHn yield better performance for SNR>20 dB  2DHn perform better in the low SNR region  1DHn always show poor performance  Results refer to a specific case study, but the analytical model is general

23. WCNC 2008 March 31 - April 3 Las Vegas Department of Information Engineering University of Padova, ITALY Mathematical Analysis of Bluetooth Energy Efficiency Andrea Zanella, Daniele Miorandi, Silvano Pupolin WPMC 2003, 21-22 October 2003 Questions?

24. WCNC 2008 March 31 - April 3 Las Vegas Extra Slides… Spare slides…

25. WCNC 2008 March 31 - April 3 Las Vegas Conditioned probabilities ACHEAD PAYLOAD 72 bits 54 bits h=220  2745 bits CRC Receiver- Correlator Margin (S) 2-time bit rep. ( 1/3 FEC) DHn: Unprotected DMn: (15,10) Hamming FEC  0 : BER

26. WCNC 2008 March 31 - April 3 Las Vegas Hypothesis  Single slave piconet  Saturated links  Master and slave have always packets waiting for transmission  Unlimited retransmission attempts  Packets are transmitted over and over again until positive acknowledgement  Static Segmentation & Reassembly policy  Unique packet type per connection  Sensing capability  Nodes can to sense the channel to identify the end of ongoing transmissions  Nodes always wait for idle channel before attempting new transmissions

27. WCNC 2008 March 31 - April 3 Las Vegas Packet error probabilities  Let us define the following basic packet reception events  A fr : AC does not check Packet is not recognized  H f : AC does check & HEAD does not Packet is not recognized  D f : AC & HEAD do check, PAYL does not Packet is recognized but PAYL contains unrecoverable errors  D s : AC & HEAD & PAYL do check Packet is successfully received  Packets experiment independent error events because of the frequency hopping mechanism

28. WCNC 2008 March 31 - April 3 Las Vegas Swapping Master and Slave* *Results not reported in the WCNC paper