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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!
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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
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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
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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!
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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, …
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WCNC 2008 March 31 - April 3 Las Vegas What standard says… Bluetooth reception mechanism
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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.
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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
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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
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WCNC 2008 March 31 - April 3 Las Vegas Mathematical Analysis System Model
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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…
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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
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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
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WCNC 2008 March 31 - April 3 Las Vegas Time reward ( T ) Master Frame Slave Frame n+m n+1 Empty slot
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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
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WCNC 2008 March 31 - April 3 Las Vegas Master energy reward ( W (M) ) Tx powerRx PowerSx power
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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!
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WCNC 2008 March 31 - April 3 Las Vegas Performance Analysis Results
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WCNC 2008 March 31 - April 3 Las Vegas AWGN
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WCNC 2008 March 31 - April 3 Las Vegas Rayleigh
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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
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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?
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WCNC 2008 March 31 - April 3 Las Vegas Extra Slides… Spare slides…
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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
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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
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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
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WCNC 2008 March 31 - April 3 Las Vegas Swapping Master and Slave* *Results not reported in the WCNC paper
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