Energy-Efficient Wireless Communication Lodewijk T. Smit
Composition of the Graduation Committee: Prof. Dr. Ir. Th. Dr. Ir. G.J.M. Ir. J.A. Prof. Dr.-Ing. J. Prof. Dr. Ir. C.H. Prof. Dr. G.J. Prof. Dr. Ir. B.R. Prof. Dr. S. Prof. Dr. H.
Krol (promoter) Smit (assistent-promoter) Huisken, Philips Natlab, Eindhoven Becker, Universit¨at Karlsruhe, Germany Slump, UT, department of Electrical Engineering W¨oginger, UT, department of Mathematical Sciences Haverkort, UT, department of Computer Science Vassiliadis, University of Delft Brinksma, UT, department of Computer Science, (chairman and secretary)
This research is conducted within the Chameleon project (TES.5004) supported by the PROGram for Research on Embedded Systems & Software (PROGRESS) of the Dutch organization for Scientific Research NWO, the Dutch Ministry of Economic Affairs and the technology foundation STW. Group of Computer Architecture, Design & Test for Embedded Systems. P.O. Box 217, 7500 AE Enschede, The Netherlands.
This thesis was edited with Vim and typeset with LATEX2e. Keywords:
energy-efficient, wireless communication, BER estimation, WCDMA, RAKE receiver, UMTS, HiperLAN/2, IEEE 802.11, control system.
c 2003 Lodewijk T. Smit, Enschede, The Netherlands. Copyright ° All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without the prior written permission of the author. Printed by Ipskamp PrintPartners, Enschede, The Netherlands. ISSN 1381-3617 (CTIT Ph.D.-thesis Series No. 60-03) ISBN 90-365-1986-1
ENERGY-EFFICIENT WIRELESS COMMUNICATION
DISSERTATION
to obtain the doctor’s degree at the University of Twente, on the authority of the rector magnificus, prof. dr. F.A. van Vught, on account of the decision of the graduation committee, to be publicly defended on Friday, January 23, 2004 at 15.00
by
Lodewijk Theodoor Smit
born on 2 April 1974, in Rijssen, The Netherlands
This dissertation is approved by: Prof. Dr. Ir. Th. Dr. Ir. G.J.M.
Krol (promoter) Smit (assistent-promoter)
and
Abstract Rapidly, the world is getting more and more connected. Internet plays a prominent role in this trend. Furthermore, people are becoming increasingly mobile. The combination of both trends results in a huge demand for wireless communication. This thesis addresses the problem of energy-efficient wireless communication with an adequate quality of service. The scarce energy resources of a mobile require an energy-efficient operation. The dynamic environment of a mobile causes large quality variation of the transport medium and requires a continuous monitoring of the quality of service of the wireless link. This thesis provides a general framework to build an energy-efficient wireless link. The central idea is to determine the exact amount of effort that is necessary to obtain the required quality given a current wireless medium. So the key is to be effective, only doing the work that is really necessary. Doing more work than necessary means waste of resources, doing less work means that the required quality of the link can not be achieved. The information about the required amount of effort for the current circumstances is used by a control system to adapt the receiver so that it will operate with minimal energy consumption. The framework is illustrated by an example of a UMTS link that is worked out in detail. A simulation environment for this example was built to illustrate the proper working of the proposed methods and to show that substantial savings can be achieved by applying these methods. A second example, which uses a completely different technology for the transmission, HiperLAN/2, is also presented. It is shown that the proposed methods can be applied to this example as well. Contributions are made on different areas: First, an algorithm is developed that provides a good indication of the quality of the medium (estimation of the BER) based on statistical analysis of the received symbols, without transmission of additional information or knowledge of the environment. Simulations show that the mean error of the v
estimation is below 2%, with only a small variance. Simulations performed at Ericsson Eurolab show the same results for a channel model that Ericsson calls a ’realistic’ channel model (so, not only an AWGN channel model is used). Second, forward error decoders are used in an unconventional way i.e. to improve a signal from bad to good, instead of the usual improvement from a good signal to a perfect signal. This may lead to a substantial reduction in the energy consumption of the receiver because a lower quality of the signal of the output at the RAKE receiver is sufficient. Third, the thesis shows how a global optimization (for QoS as well as energy consumption) can be achieved by using a cross-layer approach that ensures a seamless integration of the functionality that is usually separated in different OSI network protocol layers. Fourth, a UMTS simulation environment has been constructed, that was very useful for our experiments. Fifth, a control system has been build that uses the acquired information and proposed methods to make an adaptive system. This control system has been implemented in the UMTS simulation environment. Because of this implementation, we could verify the proper working and the benefits of using a control system. Sixth, the benefit of adaptation at run-time is shown by comparing an adaptive configuration to a commonly used static configuration that is optimized for worst case circumstances. Different scenarios have been simulated to show the differences with regard to QoS and energy consumption for different configurations (static as well as dynamic adapted configurations).
vi
Samenvatting In hoog tempo wordt de wereld met elkaar verbonden. Internet speelt een grote rol in deze ontwikkeling. Tevens worden mensen steeds mobieler. De combinatie van beide ontwikkelingen zorgt voor een grote vraag naar draadloze communicatie. Dit proefschrift richt zich op het probleem van energie effici¨ente draadloze communicatie met een adequate kwaliteitsgarantie. De beperkte middelen van een mobiel apparaat vereisen een effici¨ente werking. De dynamische omgeving van een mobiel apparaat veroorzaakt een grote wisseling in de kwaliteit van het transport medium en vereist dat de kwaliteit van de draadloze verbinding voortdurend wordt bewaakt. Dit proefschift levert een generiek raamwerk aan om een efficiente draadloze verbinding te construeren. Het kernidee is om de exacte hoeveelheid werk te bepalen die nodig is om een draadloze verbinding met de vereiste kwaliteit te verkrijgen bij een gegeven draadloos medium. Het punt is om effectief te handelen, om alleen datgene te doen wat werkelijk nodig is. Meer doen betekent verspilling van middelen, minder doen betekent dat de vereiste kwaliteit van de draadloze verbinding niet bereikt kan worden. Deze informatie over de vereiste hoeveelheid werk die nodig is voor de huidige omstandigheden wordt gebruikt door een regelsysteem om de ontvanger aan te passen zodat deze werkt met een minimaal energie verbruik. Het raamwerk wordt ge¨ıllustreerd aan de hand van een voorbeeld van een UMTS verbinding wat tot in detail is uitgewerkt. Voor dit voorbeeld is een simulatieomgeving gebouwd, die de goede werking van de voorgestelde methoden demonstreert en laat zien dat aanzienlijke besparingen kunnen worden bereikt door het toepassen van deze methoden. Een tweede voorbeeld, dat een compleet andere technologie gebruikt voor het oversturen van de data, HiperLAN/2, wordt ook uitgewerkt. Het is aangetoond dat de voorgestelde methoden ook op dit voorbeeld toegepast kunnen worden. Geleverde bijdrages op verschillende vakgebieden zijn: Ten eerste, er is een algoritme ontwikkeld dat een goede indicatie van de kwaliteit van het medium levert op basis van een statistische analyse van de vii
ontvangen symbolen, zonder het versturen van extra informatie of kennis van de omgeving. Simulaties laten zien dat de gemiddelde fout in de schatting beneden de twee procent ligt met slechts een kleine variantie. Simulaties die door Ericsson Eurolab zijn uitgevoerd laten dezelfde resultaten zijn met een model van een draadloos kanaal dat door Ericsson een ’realistisch’ kanaal model wordt genoemd (dus er is niet alleen een AWGN kanaal gebruikt). Ten tweede, fout corrigerende codes worden op onconventionele wijze toegepast om de kwaliteit van een slecht signaal te verbeteren naar een goed signaal, in plaats van de gebruikelijke verbetering van een goed signaal naar een perfect signaal. Dit kan leiden tot een substantiele verlaging van de energie consumptie van de receiver, omdat de receiver een signaal van lagere kwaliteit kan afleveren en daarom minder hoeft te rekenen. Ten derde, het proefschrift laat zien hoe een globale optimalisatie bereikt kan worden (voor de kwaliteit als wel de energie consumptie) door het naadloos combineren van functies die normaal verdeeld zijn over verschillende lagen van de OSI netwerk protocol stack. Ten vierde, een UMTS simulatie omgeving is geconstrueerd, die erg nuttig was voor het uitvoeren van onze experimenten. Ten vijfde, een regelsysteem is gebouwd dat de verkregen informatie en voorgesteld methoden gebruikt om een adaptief systeem te bouwen. Dit regelsysteem is ge¨ımplementeerd in de UMTS simulatie omgeving. Door deze implementatie konden we de juiste werking verifi¨eren en het profijt aantonen van het gebruik van dit regelsysteem. Ten zesde, het voordeel van aanpassingen op run-time wordt aangegeven versus een statische configuratie zoals die meestal wordt gebruikt en die is geoptimaliseerd voor de meest slechte omstandigheden. Verschillende scenario’s zijn gesimuleerd om de verschillen met betrekking tot zowel de kwaliteit als de energie consumptie voor verschillende configuraties te laten zien (statisch alsmede dynamisch aangepaste configuraties).
viii
BIBLIOGRAPHY [34] F. Halsall. Data Communications, Computer Networks and Open Systems. Addison-Wesley, 1992. ISBN: 0-201-56506-4. [35] P. J. M. Havinga. Mobile Multimedia Systems. PhD thesis, University of Twente, Feb. 2000. [36] P. J. M. Havinga and G. J. M. Smit. Energy-efficient wireless networking for multimedia applications. Wireless Communications and Mobile Computing, 1(2):165–184, Mar. 2001. [37] P. M. Heysters, H. Bouma, J. Smit, G. J. M. Smit, and P. J. M. Havinga. A reconfigurable function array architecture for 3g and 4g wireless terminals. In Proc of 2002 International Conference on Third Generation Wireless and Beyond, pages 399–404, May 2002. [38] P. M. Heysters, J. Smit, G. J. M. Smit, and P. J. M. Havinga. Mapping of DSP algorithms on field programmable function arrays. In Proc. of FPL 2000 (Tenth International Workshop on Field Programmable Function Arrays), pages 400–411. Springer, Aug. 2000. ISBN: 3-54067899-9; ISSN: 0302-9743. [39] V. Jacobson. Congestion avoidance and control. ACM Computer Communication Review; Proceedings of the Sigcomm ’88 Symposium in Stanford, CA, August, 1988, 18, 4:314–329, 1988. [40] V. Jacobson. Compressing TCP/IP headers for low-speed serial links, Feb. 1990. RFC: 1144. [41] V. Jacobson and R. Braden. TCP extensions for long-delay paths, Nov. 1988. RFC: 1072. [42] C. Jones, K. Sivalingam, P. Agrawal, and J. Chen. A survey of energy efficient network protocols for wireless networks. ACM Journal of Wireless Networks (WINET), 7(4), July 2001. [43] G. Kahn. The semantics of a simple language for parallel programming. In Proceedings of the Information Processing Congress, pages 471–475, Aug. 1974. [44] G. Kahn and D. MacQueen. Coroutines and networks of parallel processes. In Proceedings of the Information Processing Congress, pages 993–998, Aug. 1977. [45] P. Karn. simd-viterbi-2.0.3.tar.gz. http://www.ka9q.net/code/fec. 188
BIBLIOGRAPHY [46] J. Khun-Jush, P. Schramm, G. Malmgren, and J. Torsner. HiperLAN2: Broadband wireless communications at 5 GHz. IEEE Communications Magazine, pages 130–136, June 2002. [47] P. Lettieri, C. Fragouli, and M. B. Srivastava. Low power error control for wireless links. In Proceedings of the third annual ACM/IEEE international conference on Mobile computing and networking, pages 139–150. ACM Press, 1997. [48] O. Y.-H. Leung, C.-W. Yue, C. ying Tsui, and R. S. Cheng. Reducing power consumption of turbo code decoder using adaptive iteration with variable supply voltage. In Proceedings 1999 International Symposium on Low Power Electronics and Design, pages 36–41. ACM Press, 1999. [49] T. F. M. Bossert. Interference cancellation in the synchronous downlink of CDMA-Systems. In ITG-Fachtaging: Mobile Kommunication, pages 331–338, Sept. 1995. [50] B. Mangione-Smith. Low power communication protocols: Paging and beyond. In Proc. of Low power symposium, pages 8–11, 1995. [51] M. Mathis, J. Mahdavi, S. Floyd, and A. Romanow. TCP selective acknowledgement options, Oct. 1996. RFC: 2018. [52] R. K. Morrow. Accurate CDMA BER calculations with low computational complexity. IEEE Transactions on Communications, pages 1413– 1417, Nov. 1998. [53] B. D. Noble. Mobile Data Access. PhD thesis, Carnegie Mellon University, May 1998. [54] P. Pirinen. Impact of closed-loop power control to received WCDMA uplink signal statistics. In Proceedings of the first Finnish Wireless Communications Workshop (FWCW’00), pages 32–37, May 2000. [55] P. Pirinen. Impact of mobility and closed-loop power control to received signal statistics in Rayleigh fading channels. In Proceedings of IEEE Vehicular Technology Conference 2001 Spring, pages 2859–2863, May 2001. [56] J. Postel. Transport control protocol, Darpa internet program, protocol specification, Sept. 1981. RFC: 793. 189
BIBLIOGRAPHY [57] J. Pouwelse, K. Langendoen, and H. Sips. Dynamic voltage scaling on a low-power microprocessor. In 7th ACM Int. Conf. on Mobile Computing and Networking (Mobicom), pages 251–259, Rome, Italy, July 2001. [58] R. Price and P. E. Green. A communication technique for multipath channels. In Proceedings of the IRE, volume 46, pages 555–570, Mar. 1958. [59] P. Robertson, E. Villebrun, and P. Hoeher. A comparison of optimal and sub-optimal map decoding algorithms operating in the log domain. In Proc. International Conference on Communications (ICC), pages 1009– 1013, June 1995. [60] M. A. J. Rosien, Y. Guo, G. J. M. Smit, and T. Krol. Mapping applications to an FPFA tile. In Proceedings of DATE 2003, pages 1124–1125, Mar. 2003. [61] J. M. Rulnick and N. Bambos. Mobile power management for wireless communication networks. Wireless Networks, 3(1):3–14, 1997. [62] A. Said and W. A. Pearlsman. A new fast and efficient image codec based on set partitioning in hierarchical trees. IEEE Transactions on Circuit and Systems for Video Technology, 6:243–250, June 1996. [63] R. Schiphorst, F. W. Hoeksema, and C. H. Slump. The front end of software-defined radio: Possibilities and challenges. In proc. of 7th Annual CTIT Workshop on Mobile Communications in Perspective, pages 97–100, Feb. 2001. [64] R. Y. Shao, S. Lin, and M. P. C. Fossorier. Two simple stopping criteria for turbo decoding. IEEE Transactions on Communications, 47(8):1117–1120, Aug. 1999. [65] K. M. Sivalingam, J.-C. Chen, P. Agrawal, and M. B. Srivastava. Design and analysis of low-power access protocols for wireless and mobile ATM networks. Wireless Networks, 6(1):73–87, 2000. [66] G. J. M. Smit and P. J. M. Havinga. Lessons learned from the design of a mobile multimedia system in the moby dick project. In Proc. of Handheld and Ubiquitous Computing, Second Intermational Symposium 2000, volume 1927 of Lecture Notes in Computer Science, pages 85–99. Springer, Sept. 2000. 190
BIBLIOGRAPHY [67] L. T. Smit, G. J. M. Smit, P. J. M. Havinga, J. L. Hurink, and H. J. Broersma. Influences of rake receiver/turbo decoder parameters on energy consumption and quality. In Proc. of 2002 International Conference On Third Generation Wireless and Beyond, pages 227–235, May 2002. [68] L. T. Smit, G. J. M. Smit, and J. L. Hurink. Energy-efficient wireless communication for mobile multimedia terminals. In Proceedings of The International Conference On Advances in Mobile Multimedia, pages 115–124, Sept. 2003. ISBN: 3-85403-171-8. [69] L. T. Smit, G. J. M. Smit, J. L. Hurink, and A. B. J. Kokkeler. Soft output bit error rate estimation for WCDMA. In Proceedings of Personal Wireless Conference 2003, pages 115–124, Sept. 2003. ISBN: 3-54020123-8; ISSN: 0302-9743. [70] W. Y. Tan and W. C. Chang. Some comparisions of the method of moments and the maximum likelihood in estimating parameters of a mixture of two normal densities. Journal of the American Statistical Association, 67(33):702–708, Sept. 1972. [71] C. Teuscher, S. Sheng, I. O’Donnell, K. Stone, and R. Brodersen. Design and implementation issues for a wideband, indoor, DS-CDMA system providing multimedia access, 1996. http://bwrc.eecs.berkeley.edu/Publications/1996/. [72] G. L. Turin, F. D. Clapp, T. L. Johnston, S. B. Fine, and D. Lavry. Performance of selection diversity for a DS CDMA system with synchronization errors. Proceedings of IEEE ICUPC’95, pages 431–435, Nov. 1995. [73] M. C. Valenti. Iterative Detection and Decoding for Wireless Communications. PhD thesis, Virginia Polytechnic Institute and State University, July 1999. [74] L. F. W. van Hoesel. Design and implementation of a software defined HiperLAN/2 physical layer model for simulation purposes. Master’s thesis, University of Twente, Aug. 2002. [75] A. Worm, H. Michel, F. Gilbert, G. Kreiselmaier, M. Thul, and N. Wehn. Advanced implementation issues of turbo-decoders. In Proc. 2nd International Symposium on Turbo-Codes and Related Topics, Sept. 2000. [76] A. Xotta, D. Vogrig, A. Gerosa, A. Neviani, A. G. i Amat, G. Montorsi, M. Bruccoleri, and G. Betti. An all-analog CMOS implementation of 191
BIBLIOGRAPHY a turbo decoder for hard-disk drive read channels. In Proc. IEEE, Int. Symp. Circ. and Syst., volume 5, pages 69–72, May 2002. [77] D. Yee, C. Doan, D. Sobel, B. Limketkai, S. Alalusi, and R. Brodersen. A 2-Ghz low-power single-chip CMOS receiver for WCDMA applications. In Proc. of ESCARP, 2000.
192
Publications [1] L. Donckers, P. J. M. Havinga, G. J. M. Smit, and L. T. Smit. Energy efficient TCP. In Proceedings of the 2nd Asian International Mobile Computing Conference (AMOC 2002), pages 18–28, May 2002. ISBN:98340633-1-8. [2] L. Donckers, P. J. M. Havinga, G. J. M. Smit, and L. T. Smit. Enhancing energy efficient TCP by partial reliability. In Proc. of 13th IEEE International Symposium on Personal, indoor and mobile radio communications (PIMRC’2002), Sept. 2002. ISBN: 0-7803-7589-0. [3] P. J. M. Havinga, L. T. Smit, G. J. M. Smit, M. Bos, and P. M. Heysters. Energy management for dynamically reconfigurable heterogenous mobile systems. In Proceedings of the Heterogeneous Computing Workshop (in conjunction with IPDPS 2001), Apr. 2001. cdrom only, ISBN:0-76950990-8. [4] G. J. M. Smit, P. J. M. Havinga, M. Bos, L. T. Smit, and P. M. Heysters. Reconfiguration in mobile multimedia systems. In Proc. of PROGRESS workshop 2000, pages 95–105, Oct. 2000. ISBN 90-73461-22-7. [5] G. J. M. Smit, P. J. M. Havinga, L. T. Smit, P. M. Heysters, and M. A. J. Rosien. Dynamic reconfiguration in mobile systems. In FieldProgrammable Logic and Applications, pages 171–181, Sept. 2002. ISBN: 3-540-44108-5. [6] G. J. M. Smit, P. M. Heysters, P. J. M. Havinga, L. T. Smit, J. Smit, and J. Dilessen. Mapping the SISO module of the turbo decoder to a FPFA. In Proceedings of Second international symposium on Mobile Multimedia Systems & Applications (MMSA2000), pages 165–172, Nov. 2000. ISBN 90-9014360-2. [7] L. T. Smit and G. J. M. Smit. Efficient UMTS. I/O Vivat, 18(4):28–32, June 2003. ISSN: 1389-0468. 193
PUBLICATIONS [8] L. T. Smit, G. J. M. Smit, and P. J. M. Havinga. Run-time energy management for mobiles. In proceedings PROGRESS 2000 workshop, pages 107–112, Oct. 2000. ISBN 90-73461-22-7. [9] L. T. Smit, G. J. M. Smit, and P. J. M. Havinga. Parameter selection at run-time to optimize energy efficiency. In proceedings PROGRESS 2001 workshop, pages 227–235, Oct. 2001. ISBN 90-73461-27-X. [10] L. T. Smit, G. J. M. Smit, P. J. M. Havinga, J. A. Huisken, K. G. W. Goossens, and J. T. M. H. Dielissen. Towards a model for making a trade-off between QoS and costs. In Proceedings 7th annual CTIT workshop ’Mobile Communications in Perspective’, pages 105–109, Feb. 2001. ISBN 90-3651-5467. [11] L. T. Smit, G. J. M. Smit, P. J. M. Havinga, J. L. Hurink, and H. J. Broersma. Influences of RAKE receiver/turbo decoder parameters on energy consumption and quality. In 2002 International Conference On Third Generation Wireless and Beyond, pages 227–235. Delson, May 2002. ISSN: 1529-2592. [12] L. T. Smit, G. J. M. Smit, P. J. M. Havinga, J. L. Hurink, and H. J. Broersma. Run-time control for software defined radio. In Proceedings of the 3rd PROGRESS workshop on embedded systems, pages 218–223, Oct. 2002. ISBN: 90-73461-34-0. [13] L. T. Smit, G. J. M. Smit, and J. L. Hurink. BER estimation for wireless links using BPSK/QPSK modulation. In Proceedings of the 4rd PROGRESS workshop on embedded systems, pages 212–219, Oct. 2003. ISBN: 90-73461-37-5. [14] L. T. Smit, G. J. M. Smit, and J. L. Hurink. Energy-efficient wireless communication for mobile multimedia terminals. In Proceedings of The International Conference On Advances in Mobile Multimedia (MoMM2003), pages 115–124, Sept. 2003. ISBN: 3-85403-171-8. [15] L. T. Smit, G. J. M. Smit, J. L. Hurink, and A. B. J. Kokkeler. Soft output bit error rate estimation for WCDMA. In Proceeding of Personal Wireless Communication 2003 conference, pages 448–457, Sept. 2003. ISBN: 3-540-20123-8; ISSN: 0302-9743.
194
