Analysis of European Patent Referencing to IEEE Papers, Conferences, and Standards 1997-2008 Report prepared for: IEEE 445 Hoes Lane Piscataway, NJ 08855 www.ieee.org Report prepared by: Anthony Breitzman, Ph.D. 1790 Analytics LLC 130 Haddon Avenue Haddonfield, NJ 08033 www.1790analytics.com July 27, 2009
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Analysis of European Patent Referencing to IEEE Papers, Conferences, and Standards 1997-2008
Report prepared for:
IEEE 445 Hoes Lane
Piscataway, NJ 08855 www.ieee.org
Report prepared by:
Anthony Breitzman, Ph.D. 1790 Analytics LLC 130 Haddon Avenue
Haddonfield, NJ 08033 www.1790analytics.com
July 27, 2009
Executive Summary IEEE engaged 1790 Analytics in this project to assess the impact of IEEE publications on technology developments in several areas of Information Technology (IT). This impact is measured by examining the extent to which patented inventions related to IT build upon papers from IEEE journals, IEEE-sponsored conferences, and IEEE standards. 1790 has conducted a number of similar studies in the past using references from US patents. In this study, we examined the set of references from published European Patents (EP) to see if the results were similar. This is an update of previous reports, and examines EP patents issued from January 1, 1997 through December 31, 2008. The main findings of this report are: Patented technology frequently builds upon scientific discoveries published in
scientific journals or presented at scientific conferences. A large portion of this science base comes from papers presented at IEEE sponsored conferences and published in IEEE journals. We analyzed the top 25 largest patenting firms and found that as a set, these leading firms referenced IEEE published articles more than 12,000 times in 12 years. Approximately one-third of all science references from these firms are to articles appearing in IEEE journals or IEEE conference papers.
In this study, we also went beyond the top 25 patenting companies and analyzed
all patents from the last 12 years in several technology categories of interest to IEEE members and customers. For example, approximately 38% of all scientific references from Computer Hardware patents go to IEEE publications. To put this in perspective, the second most referenced publisher is Reed/Elsevier with just over 13% of the referenced publications. In other Information Technology areas, such as Information Storage, Semiconductor Manufacturing, and Telecom, the results are similar.
These results are consistent with the US results of earlier studies. (See [2] for
these results.) This is important because although approximately 50% of all US patents are non-US invented, it is perceived that there is a US bias which would favor US publications to the detriment of European publishers such as Elsevier. Moreover, it is widely perceived that the European patent systems referencing method is superior to the US system. This study suggests that the earlier US patent studies do not favor IEEE because of any biases within the US patent system.
To take the above bullet point a bit further, consider Executive Summary Figure
1. The US portion of the Figure is taken from the aforementioned US studies, while the EP figure is from this analysis. In general, the share of IEEE references from EP patents is similar to the share of IEEE references to US patents.
ii
We see in the Executive Summary Figure that the IEEE is first in references in nearly every category. In the non-core areas like Medical Devices and Nuclear Technology where IEEE is not first, it actually is referenced more often in EP patents than in US patents.
In Telecommunications technology, IEEE is particularly important. The 17,000+
references to IEEE articles and conferences represent almost half of all science references from Telecommunications patents since 1997. Moreover, the 17,000+ references to IEEE dwarf the combined total of the next 15 publishing organizations in this technology.
IEEE is referenced a surprising amount in areas which are not central to its
mission.
− For example, approximately 14.5% of the science references from patents in medical devices go to IEEE publications. This ranks IEEE second behind Elsevier, which has more than 400 journal titles in the area.
− Optics is also somewhat surprising. IEEE publications receive the most
references from Optics patents, and IEEE is referenced significantly more than the two large Optics Societies: SPIE – The International Society of Optical Engineering, and OSA – The Optical Society of America.
− Another non-Information Technology Area in which IEEE does very well is
Clocks & Timepieces. Nearly one-third of all references from clock related patents reference articles from IEEE.
− In Measuring, Testing, and Control, IEEE is second to Elsevier in science
references. Again, Elsevier has many more journal titles related to this topic.
− In the Nuclear, X-Ray, and Radiant Energy category IEEE is referenced third most often behind Elsevier and The American Institute of Physics. This is not terribly surprising since a large number of patents in this space are related to Nuclear Medicine where Elsevier has journal titles but IEEE has none.
− In the Robotics and Intelligent Manufacturing category, almost 40% of the
patent references are to articles published in IEEE journals or in proceedings of IEEE sponsored conferences. Second place Elsevier receives only about 18% of references in the category.
− Patents related to Power Systems and Transmission also reference IEEE
publications most frequently.
Table of Contents
Section Page I. Introduction 2 II. Methodology 2 III. Results 5 IV. Conclusions 10 V. References 11 Appendix A A-1 Appendix B B-1 Appendix C C-1
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I. Introduction In previous studies by 1790 Analytics, it was found that patents from information technology (IT) companies, and patents from several IT related technologies, tend to reference papers from IEEE journals much more often than papers from other journal publishers (see [2]). Because IEEE is a US publisher and Elsevier and others are European publishers, it has been suggested that the positive results for IEEE in past studies may be due to US inventor biases. Moreover, since European Patent Office (EPO) references are widely perceived as being more rigorous, it has been suggested that an EPO patent study might have very different results. The aim of this study was to determine whether referencing patterns from European IT patents are similar to their US counterparts. Although this report is an update of previous results, we have made our best efforts to make this report self-contained. The aim of this report, as in previous reports, is to analyze references from patents to journal articles, conferences and standards documents, in order to assess IEEE’s impact upon technological developments. This report covers 12 subcategories of Technology where IEEE members and readers are active. Many, but not all are related to Information Technology. The categories, with patent counts are shown below in Table 1. Table 1: Number of EP Patents for Each Category Covered in this Study Category # Patents 1997-2008 Clocks/Watches/Time Pieces 2159 Computer Hardware 64,868 Computer Software 28,792 Diagnosis/Surgery/Medical Instruments 72,049 Information Storage 22,508 Measuring, Testing and Control Devices 59,336 Nuclear/X-Ray/Radiant Energy 13,396 Optics/Photography/Electrophotography 33,686 Power Systems 24,023 Robotics and Intelligent Manufacturing 4,851 Semiconductors/Solid-State Devices/Electronics 32,696 Telecom and Other Communications 129,976
II. Methodology This study is based on referencing patterns from patents to prior art documents. In the European Patent (EP) system, when an inventor files a patent for a new invention, a search is undertaken by an EP searcher that will reference earlier documents to show how the new invention builds upon or differs from earlier inventions. This is done to delineate exactly what is new about the invention. So for example if someone invents a new mousetrap with an improved spring, the
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searcher will reference earlier mousetrap patents, and designs to show what has come previously. This way the inventor only gets monopoly rights to the new part of the invention (the improved spring) and does not get to claim rights to any and all mousetraps. The EP system differs from the US patent system in how references are compiled. In the US system it is primarily the job of the patent inventor and his/her lawyer to list all relevant prior art. The patent examiner will augment the list of prior art if he/she feels that additional references are needed. In the EP system the inventor does not add references. Instead, a searcher employed by the EPO and independent of the patent examiner adds all relevant references. This system is viewed as superior to the US system by many patent researchers. As an example, Figure 1 shows the front page of a Fujitsu EP patent. The prior art references on this patent come in two forms - references to earlier patents, and “other references”. These other references are often to scientific publications, such as those produced by IEEE. In this report we are primarily concerned with these other references, which are also sometimes called “Non-Patent References”. Those in yellow on Figure 1 are references that appear in IEEE journals or IEEE conferences. It has been suggested that patents with many non-patent references are likely to contain new leading-edge ideas, whereas patents that only reference earlier patents are likely to be incremental improvements on earlier patented technologies. For a comprehensive study on various hypotheses surrounding the motivations of inventors in citing other references, see [1]. It has been suggested that patents with many non-patent references are likely to contain new leading-edge ideas, whereas patents that only reference earlier patents are likely to be incremental improvements on earlier patented technologies. For a comprehensive study on various hypotheses surrounding the motivations of inventors and searchers in citing non-patent references, see [1]. A. Patent Sets This study is based on two patent sets. Our analysis is based on determining the number of references from these patent sets to publications from publishers such as IEEE, Elsevier, the American Institute of Physics, and others. The first set contains EP patents from the top 25 patenting companies in 2008. Analysis of this patent set provides an insight into how the top tier companies rely upon science from IEEE and other publishers. The second set contains all patents in twelve technology categories from all companies, universities, government agencies, and individuals. The twelve technology categories examined are shown in Table 1 above. Analysis of this patent set reveals the wider influence of IEEE science in these technologies.
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Identifying Relevant Non-Patent References Non-patent references can be to any published document, from comic strips, to brochures, to scientific articles and standards documents. The main difficulty in identifying relevant non-patent references for a study such as this is that the references are not all listed consistently. As an example, below are eight different variants for the IEEE Global Telecom Conference. Some instances use the GLOBECOM shorthand, while others list the entire name. Sometimes IEEE is mentioned and sometimes it is not. When abbreviation variations are included such as Telecom, Tele, Tcom, Proc., Proceed., the number of variants increases further. The same issue exists for variants in journal names and standards documents. Table 2 – Variants for IEEE Global Telecom Conference Proceedings of Globecom '96 IEEE Global Telecommunications Conference GLOBECOM '90:IEEE Proceedings of IEEE Globecom '94 Globecom '97 IEEE Globecom, Global Telecommunications Conference and Exhibiton Proc of the Global Tele Conf, U.S. New York, IEEE
1. Conference Identification To identify conference proceedings among the non-patent references, we first identified references containing keywords such as meeting, symposia, conference, etc. We then used software to identify 2-word and 3-word phrases that appear frequently in this set of papers. The full string was identified for these string sub-sequences in order to identify frequently cited conferences. In this way, we identified the top 400 conferences referenced in the patent sets, and standardized the names of these conferences (i.e. all of the different variants of a conference were collected under a single name). As an example, all of the variants shown in Table 2 are assigned to the name ‘<conf> IEEE Global Telecommunications Conference (GLOBECOM).’ We then looked up each of these conferences on the web to determine who is listed as their primary sponsor. For example, many of the conferences are sponsored by organizations such as IEEE, ACM (Association for Computer Machinery) and ASME (American Society of Mechanical Engineers).
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2. Standards Identification There are relatively few standards referenced (although more than in the US studies and particularly in the telecommunications sector), and in general they are easy to identify by looking for strings such as ‘standard’ or ‘std’. Once the records containing the standards were located, it was relatively easy to identify the organization that produced each standard (ETSI, ISOC, IEEE, ISO, JEDEC, ANSI, etc.).
3. Journal Identification Identifying and standardizing journal names is a very difficult process because there are so many different journals, and their names can be abbreviated in many different ways. To make the problem more manageable, we restricted our analysis to the 14,000+ journals covered by the ISI/Thomson Scientific Database. This is not a severe limitation, since these 14,000+ journals include more than 100 IEEE journals, 1400+ Elsevier journals, and 350+ Wiley journals. In addition, we also identify some non-ISI journals if they appear very frequently in the patent references, but do not appear in the ISI database. Once restricted to these 14,000 journals, we used software that transforms journal names into common abbreviations and then implements string matching. Care must be taken with string matching because, for example, searching for “Urology Journal” will also accidentally identify “Neurology Journal”. Similarly, a search for the journal “Science” would accidentally pick up any reference with ‘science’ in the paper title as well as any of the 800+ journals with science in their titles such as “Game and Wildlife Science”. Our proprietary software for journal identification deals with all of these problems, so that we generate an accurate match between the patent references and 14,000+ journals. After identifying all of the relevant journals, we then used the ISI database and web research to identify the publisher of each journal. III. Results References from Top 25 Patenting Organizations Table 3 shows the 25 firms that were granted the largest number of US patents in 2008. It should be noted that many of these firms consist of multiple subsidiaries, and these firms patent under many names. We identified all of the subsidiary names for each company to ensure that our patent counts are accurate. We identified the top 25 patenting firms because we want to understand the extent to which the current technology leaders use IEEE science. Figure 2 shows the 20 publishers of science whose publications are referenced most frequently by the 25 firms shown in Table 3. This figure shows that patents issued to the top 25 firms between 1997 and 2008 reference IEEE papers, conferences, and standards more than 12,000 times. This is more than 1.5 times as many references as the second placed publisher (Reed/Elsevier) and almost 5 times as many as third place American Chemical Society.
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Table 3 – Top Patenting Firms in 2008
Assignee 2008 US Patent
Count 1997-2008 US Patent
Count Samsung Electronics Co Ltd 2129 11247 Siemens Aktiengesellschaft 1983 23379 Koninklijke Philips Electronics N.V. 1815 20495 Bosch (Robert) GmbH 1393 13888 Panasonic Corporation 1060 14601 BASF SE 1043 10792 Qualcomm Inc 984 4152 LG Electronics Inc. 980 5618 Fujitsu Limited 922 6823 Toyota Motor Company 902 6171 General Electric Company 893 8533 Hitachi Ltd 865 7728 Johnson & Johnson 831 7517 Honeywell International Inc. 816 4914 Sony Corp 783 11121 Nokia Corp 759 7408 Bayer AG 676 8154 Fuji Film Holdings Corp 673 5307 United Technologies Corp 640 3702 Microsoft Corporation 634 3740 Roche HoldingLtd. 629 4948 Alcatel-Lucent 618 11308 3M 612 6506 Research in Motion Ltd. 609 2169 Procter & Gamble Co. 600 8647
Table 4 illustrates the reference distribution of Samsung, one of the top 25 firms. This reference distribution is fairly typical of the top 25 firms. The references from Samsung to IEEE are actually to a number of different IEEE journals and conferences. In this table, IEEE journals are highlighted in yellow, IEEE conferences are highlighted in orange, and IEEE standards are highlighted in green. As a telecom firm, Samsung tends to reference a lot of standards. However among the 10 journals most referenced by Samsung, seven are IEEE journals. A full 24 of the 50 entries in Table 4 represent references to IEEE articles, standards, and conference titles. This compares favorably with second ranked Elsevier, whose journals are in the table only 8 times. The reader may notice the large number of references to ‘IEEE Unseparated’. These are articles that reference IEEE, but the inventor has not given name specific enough to identify the proper journal or conference. For example consider: IEEE, 14 November 1994, Kitamura, "Design of the ISDN PC Card", pp. 1169, 1170, 1171. This reference is to an IEEE journal, but the inventor has not provided enough information to name the journal title.
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Table 4 – Reference Distribution from Samsung EP Patents 1997-2008 # References journal/conference/standard
118 IEEE Unseparated 93 <std> IETF Std 82 <std> GPP General Partnership Project Tech Spec 55 <conf> IEEE Misc Conf 52 Proc SPIE 50 <std> European Telecom Standards Institute (ETSI) 48 ELECTRONICS LETTERS 44 IEEE tr CONSUMER ELECTRONICS 36 <std> TSG RAN Working Group 34 <std> ISO/IEC/JTC Std 32 IEEE tr COMMUNICATIONS 31 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 31 JAPANESE JOURNAL OF APPLIED PHYSICS 31 IEEE tr Circuits and sys for Video tech 27 IEEE COMMUNICATIONS MAGAZINE 27 IEEE PHOTONICS TECHNOLOGY LETTERS 26 <std> ISO Std 23 <conf> IEEE Global Telecommunications Conference (GLOBECOM) 20 Elsevier Misc 20 SIGNAL PROCESSING-IMAGE COMMUNICATION 19 <std> ITU Telecom Standard 18 <conf> IEEE Int Conf Acous, Speech, and Sig Proc (ICASSP) 17 Misc IEEE 17 <std> IEEE Std 17 IEEE tr INFORMATION THEORY 17 IEEE Proceedings 15 <conf> IEEE Vehicular Tech Conf 15 APPLIED PHYSICS LETTERS 14 SENSORS AND ACTUATORS 14 <conf> IEEE int conf on comm (ICC) 14 PATTERN RECOGNITION 12 <std> ECMA Std 12 ACS-Amer Chem Soc (Misc)
11 <conf> IEEE Wireless and Communications and Networking Conference (WCNC)
11 IEEE tr PATTERN ANALYSIS AND MACHINE INTELLIGENCE 11 PATTERN RECOGNITION LETTERS 10 <conf> IEEE int conf on imag proc 9 COMPUTERS & GRAPHICS 9 IEEE COMMUNICATIONS LETTERS 9 IEICE TRANSACTIONS ON COMMUNICATIONS 9 IEEE Personal comm 9 IEEE JOURNAL OF SOLID-STATE CIRCUITS 9 <conf> IEEE Int Electron Devices Meeting (IEDM) 8 NATURE 8 ADVANCED MATERIALS 7 COMMUNICATIONS OF THE ACM 7 JOURNAL OF APPLIED PHYSICS 7 JOURNAL OF ORGANOMETALLIC CHEMISTRY 7 COMPUTER NETWORKS AND ISDN SYSTEMS 7 IEEE MICRO
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References from Companies in Twelve Technology Categories In the previous section, we analyzed the use of IEEE science by the top patenting organizations. Out of all science publishers, IEEE was cited most often by these organizations by a wide margin. However, looking only at the top companies tells an incomplete story. IEEE publishes journals and runs conferences mainly in information technology, electronic and other areas. It is therefore useful to examine the extent to which IEEE science is referenced by all organizations that patent in specific technologies and not just the leading companies. As mentioned in the methodology section, we identified all patents in the twelve technology categories shown above in Table 1. 1790 Analytics has developed a classification scheme that categorizes all patents into 50 broad technology areas. This categorization scheme as well as specific International Patent Classes, were used to identify all relevant patents for this part of the analysis. We examined each of the twelve technology areas separately, and the results are summarized in Figures 3-14. The first category shown (in Figure 3) is Clocks, Watches, and Timepieces. We identified all non-patent references on patents related to this technology issued between 1997 and 2008. We then determined the science publishers responsible for the largest number of these non-patent references. Figure 3 shows the result of this analysis, namely that IEEE science is referenced far more by clock and watch related patents than science from any other publisher. More than one-third of all science references from these patents go to IEEE journal papers or IEEE sponsored conference papers (the graphs also include standards documents, but the vast majority of the references are to journal or conference papers). Figures 4 and 5 are analogous to Figure 3 except they show referencing patterns from Computer Hardware and Software patents. Here IEEE once again receives far more references than the other publishers. In both cases, Elsevier is the second most referenced publisher, but it receives less than half of the references that IEEE does. Figure 6 examines the top referenced publishers in the Medical Device field, which covers devices as well as diagnostic tools and surgical instruments. Here, IEEE is a surprisingly respectable second in an area that is somewhat outside its core competency. Elsevier has more than 400 journals in the medical field, including Annals of Thoracic Surgery, and the Journal of the American College of Cardiology. Lippincott Williams and Wilkins, which publishes more than 100 health and diagnostic related journals, including Circulation, Neurosurgery, Investigative Radiology, Anesthesiology, and Annals of Surgery is ranked fourth. IEEE has relatively few medical journals but has many patent references to articles appearing in IEEE Transactions on Biomedical Engineering and IEEE Transactions on Medical Imaging. Figure 7 shows the results for the information storage category. In this area, IEEE is particularly dominant. A full 42% of all of the science references from patents in information storage are to papers in IEEE journals or conferences. IEEE’s 1,356 references in this category are more than 4 times as many as second place Elsevier.
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Figure 8 shows the results of patents covering Measuring, Testing, and Control technology. Patents in this category are related to measuring or testing, force, pressure, weight, etc. as well as chemically measuring substances (e.g. measuring CO2 levels). The category also contains control devices since these technologies are often combined. For example a patent might be related to a valve that adjusts at a certain pressure or at a certain pollution level. Since this type of measuring can be done both mechanically, magnetically, electrically, or chemically, it is not too surprising to see both IEEE and Elsevier and the American Chemical Society all near the top of Figure 8. Elsevier receives the most references, but IEEE is a fairly close second. Figure 9 contains reference counts for Nuclear and X-Ray technology patents. Much of the patenting in this category is related to Nuclear Medicine so it is not surprising that the top referenced publisher is Elsevier. IEEE is third in referencing in this category behind Elsevier and the American Institute of Physics. The results for the Optics category can be found in Figure 10. This is another area that is slightly outside the IEEE core. IEEE still has a substantial lead over the second and third place publishers - the International Society of Optical Engineering (SPIE) and the Optical Society of America (OSA). Since these latter two societies are Optical societies, it would be reasonable to assume that one of these societies would lead in the category, but IEEE strong journals and conferences in the area receive more references. Figure 11 shows reference counts for the patents related to power generation and transmission. Although this is a non-information technology category, IEEE leads in references in this category as well. About 38% of science references from patents in this category go to IEEE publications. Intelligent Manufacturing and Robotics contains patents related to robotics, and robotics and control systems related to manufacturing. According to Fortune Magazine [3] the Robotics industry is a $5 billion global industry that is expected to triple in size within the next 5 years as a result of a population explosion in “service robots” that mow lawns, vacuum floors, and manufacture things. As this industry grows, new innovations will be patented, and from Figure 12 it looks like those innovations will build upon ideas published in IEEE journal articles or presented at IEEE conferences. We see in Figure 12 that nearly 39% all science references from patents in this space refer to IEEE published articles. Elsevier is the second ranked publisher, but it has fewer than half as many references as IEEE. In this category, IEEE has more references then the next 8 publishers combined. Figure 13 shows that IEEE is also very strong in the Semiconductor category. Here, the inclusion of conferences gives IEEE a substantial boost. A little less than one-third of the references to IEEE are to conference papers. With conferences excluded, IEEE would be about even with the American Institute of Physics in terms of science references from semiconductor patents. In the Telecommunications category, IEEE receives more than nine times as many references as the second place publisher (IEE). Standards are referenced more frequently in
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telecommunications, but still not nearly as often as journal and conference papers. About 60% of the science references to all publishers are to journal articles; 26% of the references are to conference papers, and about 14% are to standards documents. In terms of standards documents, the Internet Engineering Task Force (IETF) and European Telecom Standards Institute (ETSI) received the most references in the category with 2,088 and 944 references respectively. Figures 3-14 show aggregate counts of references from all patents in each technology category. Readers who wish to see the firms that reference IEEE publications in each category can consult Appendix B. This appendix contains the 100 organizations that reference IEEE most frequently in each category. Appendix C is similar, except that it contains the organizations that reference IEEE most frequently in the twelve technology categories combined. IV. Conclusions When a patent is filed, it must reference the prior art upon which it builds, as well as any prior art that limits the claims of the new invention. This study and prior studies show that science published by IEEE forms a significant portion of this prior art for new patents. In this study, we examined two separate patent sets. The first patent set consisted of patents granted between 1997 and 2008 to the 25 organizations with the largest number of EP patents granted in 2008. The second patent set consisted of all EP patents granted between 1997 and 2008 patents in twelve key technologies: clocks, computer hardware, software, nuclear/x-ray, robotics, semiconductors, measuring and testing, medical devices, telecommunications, optics, power systems, and information storage. In both of these patent sets, IEEE is the dominant source of non-patent prior art. In other words, IEEE journals and conferences are key outlets for scientific discoveries relevant to cutting edge technology. We have conducted a number of similar analyses for US patents and found similar results. By repeating the analysis and getting similar results for European patented technology, we have achieved the following:
1. We showed that respect for and use of IEEE published science is not restricted to US inventors and scientists.
2. We showed that high referencing to IEEE published science in US patents is not due to
any biases in the way that the US citations are gathered. The EP patent system with its independent search system is viewed as superior to the US system, where patent references are compiled by the inventor, inventor’s attorney, and patent examiner. However we have shown that the referencing patterns to science are similar in both systems, and that the IEEE is an important outlet for science that is built upon by leading edge technology.
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V. References [1] Branstetter, Lee. “Is Academic Science Driving a Surge in Industrial Innovation? Evidence from Patent Citations,” Columbia Business School, Discussion Paper #28. [2] Breitzman, Anthony. "IEEE and Patents: An Analysis of Patent Referencing to IEEE Papers, Conferences and Standards", 1790 Analytics, LLC, March 2009. [3] Fortune Magazine, “Ten Tech Trends,” January 10, 2005.
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Figure 1: Front Page of Patent #EP1063776
Turbo DecoderPublication number: EP1063776 (A3)
Publication date: 2003-11-26
Inventor(s): YANO TETSUYA [JP]; OBUCHI KAZUHISA [JP]; KAWABATA KAZUO [JP]
Applicant(s): FUJITSU LTD [JP]
Classification:
- international: H03M13/13; H03M13/29; H03M13/39; H03M13/00; (IPC1-7):H03M13/29
- European: H03M13/29T4L; H03M13/29; H03M13/29T
Application number: EP20000110944 20000525
Priority number(s): JP19990176617 19990623
AbstractA turbo decoder is provided in which a distribution of likelihood values that are obtained during the course of turbo-decoding
is watched and scaling of an operation object to be subjected to subsequent likelihood computation of the turbo-decoding is
performed in accordance with the distribution. This turbo decoder can reduce the cost, size, and power consumption of a
transmission system and equipment, increase their reliability, and improve the transmission quality and performance.
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XP000782280 (A) XP000768532 (A) XP010303741 (A) XP010062790 (A) XP010226998 (A)
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pages 102-106.
GIBONG JEONG ET AL. Optimal quantization for soft-decision turbo decoder, PROC. OF VEHICULAR TECHNOLOGY
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OF GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM), vol. 1, 6 December 1992, pages 1255-1259.
LANG LIN ET AL. Improvements in SOVA-based decoding for turbo codes, PROC. OF IEEE INTERNATIONAL
CONFERENCE ON COMMUNICATIONS, 8 June 1997, pages 1473-1478.
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125
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116
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77
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70
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63
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)
52
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48
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)
47
(1.0
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40
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NO
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108
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136
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120
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102
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