삶, 원두 커피 향기, 그리고 컴퓨터..

The Bluetooth radio chip uses GFSK Modulation. It is natural to assume that GFSK is quite like FSK Modulation, however the differences between the 2 are substantial in implementation and results (output)

Question 1
What are the physical Differences between an FSK & GFSK Modulator, and how do their results vary?
Answer 1
An FSK Modulator is much the same as a GFSK Modulator ,but GFSK uses a Gaussian filter as well. In a GFSK modulator everything is the same as a FSK modulator except that before the baseband pulses (-1, 1) go into the FSK modulator, it is passed through a gaussian filter to make the pulse smoother so to limit its spectral width.

Question 2
What is Gaussian Filtering?
Answer 2
Gaussian filtering is one of the very standard ways for reducing the spectral width, it is called Pulse Shaping. If we use -1 for fc-fd and 1 for fc+fd, once when we jump from -1 to 1 or 1 to -1, the modulated waveform changes rapidly, which introduces large out-of-band spectrum. If we change the pulse going from -1 to 1 as -1, -.98, -.93 ..... .96, .99, 1, and we use this smoother pulse to modulate the carrier, the out-of-band spectrum will be reduced.

Question 3
So, why is GFSK implemented in Bluetooth Radios , and not FSK , is it cheaper?
Answer 3
The spectral width for FSK is unlimited, comparatively, there is a limitation on GFSK. fc "climbs slowly" to fd in GFSK, However, in the case of FSK, fc "jumps sharply" to fd, which greatly decreases spectral efficiency.

GFSK is not implemented in the Bluetooth radio unit for cheaper chips (since you need to put an extra pulse-shaping filter in front of the modulator), but for spectral efficiency.

ps.
1. Gaussian filtering에 대해 자세히 알고 싶으면 아래 사이트를 참고할 것!
  http://homepages.inf.ed.ac.uk/rbf/HIPR2/gsmooth.htm
  http://www.fho-emden.de/~hoffmann/gauss25092001.pdf
2. FSK는 무선 랜에서 사용되는 변조 방식임.

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Bluetooth has been designed to operate in noisy radio frequency environments, and uses a fast acknowledgement and frequency-hopping scheme to make the link robust, communication-wise. Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet.
Compared with other systems operating in the same frequency band, the Bluetooth radio typically hops faster and uses shorter packets. This is because short packages and fast hopping limit the impact of microwave ovens and other sources of disturbances. Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links.

Considering the figure 1, one realizes that hopping out-and-into a continuous range of frequencies that are subject to noise gives the communications link a better chance to remedy transmission errors when out of the disturbed frequencies, than would have been the case if the transmission had stayed for several timeslots within the noisy frequency range. This argument does not hold true if the noise is spread over the whole frequency range in a random fashion, but sources of electro-magnetic noise usually give the pattern illustrated in figure 2.

Whenever a connection (a "piconet") is first established between 2 (or more) units, the Master-unit establishes a frequency-hopping scheme, which is communicated to the other units. This frequency selection scheme consists of two parts:

• selecting a sequence;
• mapping this sequence onto the hop frequencies.

The mapping from the input to a particular hop frequency is performed in the selection box. Basically, the input is the native clock and the current address. In the CONNECTION state, the native clock is modified by an offset to equal the master clock. Only the 27 MSBs of the clock are used. In the page and inquiry substates, all 28 bits of the clock are used. However, in the PAGE substate the native clock will be modified to the master estimate of the paged unit.

The frequency-hopping schemes

10 types of frequency-hopping sequences are defined ?5 for the 79-hop and 5 for the 23-hop system. These sequences are:

1. A page hopping sequence with 32 (16) unique wake-up frequencies, distributed equally over the 79 (23) MHz, with a period length of 32 (16).
2. A page response sequence covering 32 (16) unique response frequencies that are all in a one-to-one correspondence to the current hopping sequence. Master & Slave use different rules to obtain the same sequence.
3. An inquiry sequence with 32 (16) unique wake-up frequencies, distributed equally over the 79 (23) MHz, with a period length of 32 (16).
4. A inquiry response sequence covering 32 (16) unique response frequencies that are all in a one-to-one correspondence to the current inquiry hopping sequence.
5. A channel hopping sequence with very long period, which does not show repetitive patterns over a short time interval, but which distributes the hop frequencies equally.

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1. http://www.bluetooth.com
BT에 관한 포탈 사이트와 비슷하다. BT에 대한 간단한 개념과 참여업체, 적용 제품에 관하여 설명하고 있는 잡지성(?) 사이트라고 볼 수 있다.

2. http://www.bluetooth.org
공식 멤버쉽 사이트로 기술적이 내용이 주를 이루고 있다. 스펙과 같은 개발에 관련된 문서를 구하려면 방문할 것!

3. http://www.csr.com
BT 솔루션 판매 업체로 정확하게 잘 모르겠지만 애플에서 이곳 칩셋과 API를 이용하는 것 같다. 외국에서 가장 많이 사용하는 칩셋으로 생각된다.

4. http://www.palowireless.com/bluetooth/
Bluetooth Resource Center라는 제목에 걸맞게 BT 입문자, 개발자, 마케팅 담당자, 온라인 상점 등 여러 분야에서 필요한 리소스의 링크를 가지고 있다.

5. http://www.bluez.org
리눅스에서 BT 프로토콜 스택을 구현하는 프로젝트인 BlueZ의 공식 사이트이다. 공개된 소스코드를 여기서 구할 수 있다.

6. http://www.holtmann.org/linux/bluetooth/
BT HOWTO 문서를 정리해 놓은 사이트로 특히 리눅스와 관련된 문서가 많다.

7. http://www.thewirelessreport.com/category/bluetooth/
BT에 관한 블로그로 잡지성 기사가 많다.

8. http://kde-bluetooth.sourceforge.net/
KDE에 BuleZ를 사용하여 BT 프레임워크를 만들기 위한 프로젝트

9. http://www.eng.tau.ac.il/~yash/shaked-wool-mobisys05/
BT PIN을 이용한 공격을 구현한 논문으로 보안 이슈를 중점적으로 다루고 있다. 참고문헌에 BT 보안에 관련된 링크가 많다.

10. http://www.korwin.co.kr/kor/
BT와 ZigBee 라이브러리를 개발하는 우리나라 업체로 한번 살펴볼만 하다.

11. http://www.sds.samsung.co.kr/support/epartner/itreview/data/epci001t/bluetooth1.pdf
삼성 SDS에서 만든 간단한 한글 보고서로 BT에 대해 쉽게 정리되어 있다.

검색 결과 아직까지 국내에서는 전문적인 자료를 구하기 힘들다는 느낌이 듭니다.

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출처: 진주대학, 동국대학

색인과 검색
string match

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introduction to PDA
CFG and PDA
PDA

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download pdf

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출처: A. Silberschatz, H. F. Korth, and S. Sudarshan. Database System Concepts 4th Edition. McGraw-Hill. 2002.

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출처: From James Power (James.Power@May.ie)
Department of Computer Science, National University of Ireland, Maynooth, Maynooth, Co. Kildare, Ireland.

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I have various lumps of information about computer languages, parsing, grammars, and compilers. This is an ongoing (and thus, as yet, incomplete) attempt to make this information more accessible and more useful.

Complete and integrated:

• The Tower of Babel - Computer Languages
  
• BNF, Syntax Diagrams & EBNF
  
• Bending grammars to your will

Complete, but not integrated (old lecture notes, no longer being maintained):

• A book: Compiler Engineering Using Pascal
  
• A brief introduction to Programming Language Paradigms
  
• A brief introduction to Assemblers and Compilers
  
• CS2121: Implementation and Power of Programming Languages
  
• The compilers half of CS5031: System Software, given in autumn 1998 and autumn 1999
  
• CS2111: Design and Implementation of Programming Languages

In progress:

• lex and yacc
  
• programming languages, design, and implementation (compilers)
  
• L, a teaching language
  
• faq
  
• java
  
• 3rd year and msc projects

Useful (?) links:

• Upcoming Compiler and Parallel Computing Conferences
  
• Unified Computer Science TR Index Simple Index Keyword Search
  
• C FAQ index
  
• Comparisons of ICE Tcl with other Systems
  
• Linkers and Loaders
  
• Online books and tutorials about compiling:
  
  
  
  • COMPILERS AND COMPILER GENERATORS an introduction with C++ by P.D. Terry
    
  • Parsing Techniques - A Practical Guide by Dick Grune and Ceriel J.H. Jacobs
    
  • Let's Build a Compiler by Jack Crenshaw
  
  
• Compiler software etc.
  
  
  
  • Catalog of Compiler Construction Tools
    
  • Catalog of Free Compilers and Interpreters
    
  • Catalog of Compiler Construction Products
    
  • FAQ for news:comp.compilers

Several lists of links that need tidying (i.e. probably deleting!):

• *
  
• *
  
• *
  
• *
  
• *
  
• *
  
• html/*

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This page is maintained by and copyright © Pete Jinks [last modified 25/Mar/2004] suggestions, corrections etc. welcome You are welcome to make educational, not-for-profit use (else what would be the point!) but please give due credit.

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Papers on XPath/XQuery Evaluation

"Efficient Filtering of XML Documents for Selective Dissemination of Information"
Mehmet Altinel, Michael J. Franklin (pdf)

"Path Sharing and Predicate Evaluation for High-Performance XML Filtering"
Yanlei Diao, Mehmet Altinel, Michael J.Franklin, Hao Zhang, Peter Fischer (pdf)

"Processing XML Streams with Deterministic Automata"
Todd J. Green, Gerome Miklau, Makoto Onizuka, Dan Suciu (ps)

"Stream Processing of XPath Queries with Predicates"
Ashish Kumar Gupta, Dan Suciu (pdf)

"TIMBER: A Native XML Database."
H. V. Jagadish, Shurug Al-Khalifa, Adriane Chapman, Laks V.S. Lakshmanan,
Andrew Nierman, Stelios Paparizos, Jignesh M. Patel, Divesh Srivastava, Nuwee
Wiwatwattana, Yuqing Wu and Cong Yu. (pdf)

"Using Histograms to Estimate Answer Size for XML Queries"
Yuqing Wu, Jignesh Patel, H. V. Jagadish. (pdf)

"Structural Join Order Selection for XML Query Optimization"
Yuqing Wu, Jignesh Patel and H.V. Jagadish (pdf)

"Querying structured text in an XML database"
Shurug Al-Khalifa, Cong Yu and H.V. Jagadish. (pdf)

"From Tree Patterns to Generalized Tree Patterns: On Efficient Evaluation of XQuery"
Zhimin Chen, H.V. Jagadish, Laks V.S. Lakshmanan and Stelios Paparizos (pdf)

"Holistic Twig Joins: Optimal XML Pattern Matching"
Nicolas Bruno, Nick Koudas, Divesh Srivastava (pdf)

"Path Queries on Compressed XML"
Peter Buneman, Martin Grohe, Christoph Koch (pdf)

"Efficient Algorithms for Processing XPath Queries"
Georg Gottlob, Christoph Koch, Reinhard Pichler (pdf)

"Efficient Filtering of XML documents with XPath expressions"
Chee-Yong Chan, Pascal Felber, Minos Garofalakis, Rajeev Rastogi (pdf)

"Streaming XPath Processing with Forward and Backward Axes"
Charles Barton, Philippe Charles, Marcus Fontoura, Vanja Josifovski, Deepak Goyal,
Mukund Raghavachari (pdf)

"Navigation vs. Index-Based XML Multi-Query Processing"
Nicolas Bruno, Luis Gravano, Nick Koudas, Divesh Srivastava (pdf)

"XPath Queries on Streaming Data"Feng Peng, Sudarshan S. Chawathe(ps)

Papers on Data Broadcast

"Dissemination-Based Data Delivery Using Broadcast Disks"
Swarup Acharya, Michael Franklin, and Stanley Zdonik (pdf)

"Adaptive Data Broadcasting Using Air-Cache"
Konstantinos Stathatos, Nick Roussopoulus and John S. Baras (ps)

"Data Staging for On-Demand Broadcast"
Demet Aksoy and Michael J.Franklin, Stan Zdonik (pdf)

Papers on Push vs. Pull

"Data in your Face: Push Technology in Perspective"
Michael Franklin and Stan Zdonik (pdf)

"Balancing Push and Pull for Data Broadcast"
Michael Franklin and Stan Zdonik and Swarup Acharya. (pdf)

"Broadcast Scheduling for Information Distribution"
Chi-Jiun Su and Leandros Tassiulas (pdf)

"Adaptive Push-Pull: Disseminating Dynamic Web Data"
Manish Bhide, Pavan Deolasee, Amol Katkar, Ankur Panchbudhe,
Krithi Ramamritham, Prashant Shenoy (pdf)
 

Related Projects

Niagara at University of Wisconsin, Madison

Telegraph at University of California, Berkeley

XSM Project at University of California, San Diego

XSQ Project at University of Maryland

Timber at University of Michigan

Tukwila Data Integration System at University of Washington, Seattle

Lore at Stanford

STREAM at Stanford

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