DOCSLIB.ORG

Performance Analysis of Asymmetric Constellation in Concatenation with Trellis Coded

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Performance Analysis of Asymmetric Constellation in Concatenation with Trellis Coded A Thesis entitled Performance Analysis of Asymmetric Constellation in Concatenation with Trellis Coded Modulation for use in Intelligent Systems by Abbas Firoz Saboowala Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Electrical Engineering Dr. Kim Junghwan, Committee Chair Dr. Mohammed Niamat, Committee Member Dr. Kim Dong-Shik, Committee Member Dr. Patricia R. Komuniecki, Dean College of Graduate Studies The University of Toledo May 2011 An Abstract of Performance Analysis of Asymmetric Constellation in Concatenation with Trellis Coded Modulation for use in Intelligent Systems by Abbas F. Saboowala Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Electrical Engineering The University of Toledo May 2011 This thesis is on trellis coded modulation (TCM) schemes with asymmetrical constellation. This modulation technique can be easily adapted to the intelligent systems like Cognitive Radio and Software Defined Radio (SDR) with improved error performance. Different types of asymmetric constellation methods for QPSK, 8-PSK and 16-PSK are used, which result in better performance compared to the case of standard symmetrical constellation assignment. In a cognitive radio environment, the channel conditions change frequently. Thus it suggests the requirement for a non-linear adaptive modulation technique with variable parameters. This requirement can be met by using trellis coded modulation with asymmetrical constellation [15,16]. The approach to this thesis is to use digital modulation techniques namely M-ary Phase Shift Keying (MPSK), in combination with convolutional codes of specific code rate, and then combining these convolutional codes to a TCM mapper, and finally iii carrying out TCM encoding and decoding. Towards this, the following steps are performed; designing the convolutional encoder based on Ungerboeck‟s design scheme, using a signal mapper to map the modulation scheme, making use of Ungerboeck‟s set partitioning technique to obtain the maximum distance between signals [2], obtaining the trellis which maximizes the performance, and carrying out decoding using the Viterbi algorithm [18]. The method used in this thesis yields an improvement in error, minimum distance and coding gain as compared to those of conventional trellis coded modulation technique. iv Acknowledgements I would firstly like to thank the All Mighty God, for venturing me through thick and thin. Also, I would like to express my most sincere gratitude and gratefulness to His Holiness Dr. Syedna Mohammed Burhanuddin saheb, whose blessings and guidance have helped me at every stage of my life. I owe my deepest gratitude to my advisor, Dr. Junghwan Kim, who has helped and supported me throughout my research and academic program. I would also like to thank Dr. Niamat Mohammed and Dr. Dong-Shik Kim, for serving as members on my thesis defense committee. I am also very thankful to the Engineering Technology Department, Scott Park Library and Law School for having provided a wonderful ambience to work in. A special thanks to my wonderful friends Taher Kagalwala, Hozefa Jodiyawala, Mohammed Taskeen, Aliasgar Presswala, Widian Abi Saab, Alafiya Nasrulla, Javed Mapkar, Desikan Sundarajan, Shachi Mistry and Jessica Stewart for their constant support and help. An extended thanks to Taher Kagalwala and Wang Chong for helping me with my research. My deepest gratitude goes to my parents and family who have always been my strength and source of encouragement, especially my mother, Munira Saboowala and sister, Fatema Saboowala. Also, I express my sincere gratitude to Zainab Kothari and the entire Kothari family for always being by my side throughout my Master‟s program. v Table of Contents Abstract …... ...………………………………………………………………………….iii Acknowledgements …………………………………………………………………….v Table of Contents..............................................................................................................vi List of Figures ................................................................................................................viii 1 Introduction…………………………………………………………………………..….1 1.1 Digital Communication ..........................................................................................1 1.2 Cognitive Radio (CR) .............................................................................................2 1.2.1 Adaptive Modulation and Coding in Cognitive Radio ......................................5 1.3 Trellis Coded Modulation .......................................................................................7 1.3.1 TCM Concepts .................................................................................................9 1.4 Outline of Thesis .................................................................................................. 12 2 Modulation and Asymmetric TCM…………………………………………………….13 2. 1 Modulation Technique......................................................................................... 13 2.2 Asymmetric Constellation in TCM ....................................................................... 17 2.2.1 System design ................................................................................................ 19 2.2.2 TCM Encoder ................................................................................................ 21 2.2.3 Mapping ........................................................................................................ 25 2.2.4 Viterbi Decoding ........................................................................................... 28 3 Generalized System Performance Analysis ……………………………………………31 3.1 System Performance ............................................................................................. 31 3.2 Relation Between dfree and BER ........................................................................... 36 3.3 Relation Between Phase Jitter and Error Probability ............................................. 37 4 Performance Improvement for PSK Schemes…………………………………………40 4.1 Asymmetric 4-PSK, 2 State, Rate 1/2 ................................................................... 40 vi 4.2 Asymmetric 4-PSK, 4 State, Rate 1/2 ................................................................... 47 4.3 Asymmetric 4-PSK, 8 State, Rate 1/2 ................................................................... 51 4.4 Asymmetric 8-PSK, 4 State, Rate 2/3 ................................................................... 54 4.5 Asymmetric 8-PSK, 8 State, Rate 2/3 ................................................................... 57 4.6 Asymmetric 8-PSK, 16 State, Rate 2/3 ................................................................. 60 4.7 Asymmetric 16-PSK, 8 State, Rate 3/4 ................................................................. 63 5 Results and Discussions………………………………………………………………..67 5.1 Simulation Results ............................................................................................... 67 6 Conclusion and future work ……………………………………………………………83 6.1 Conclusion ........................................................................................................... 83 6.2 Future Work ......................................................................................................... 84 References………………………………………………………………………………..85 vii List of Figures Figure 1.1: Logical diagram contrasting traditional radio, software radio, and cognitive radio ...............................................................................................................3 Figure 1.2: Functional portions of a cognitive radio, representing reasoning and learning capabilities .....................................................................................................4 Figure 1.3: Block diagram for Adaptive Modulation based Cognitive Radio ....................6 Figure 1.4: 8 PSK constellation and squared Euclidean distances between symbols .........9 Figure 1.5: Euclidean and sequence Hamming distance ................................................. 10 Figure 2.1: Bit error rate (BER) of BPSK ...................................................................... 14 Figure 2.2: BER simulation of QPSK ............................................................................ 15 Figure 2.3: BER simulation of 8-PSK ............................................................................ 16 Figure 2.4: Symmetric 8PSK Constellation .................................................................... 18 Figure 2.5: ASYMMETRIC 8PSK Constellation ........................................................... 19 Figure 2.6: System block diagram for asymmetrical TCM ............................................. 19 Figure 2.7: A general trellis coded modulation ............................................................... 22 Figure 2.8: Constellation doubling in TCM showing a QPSK signal transmitted using a 8PSK constellation ....................................................................................... 23 Figure 2.9: Signal doubling that takes place in TCM represented with an example for BPSK, QPSK and 8-PSK.............................................................................. 24 viii Figure 2.10: Set Partitioning of Asymmetric 8PSK ........................................................ 27 Figure 2.11: Example of a Trellis Diagram .................................................................... 28 Figure 4.1: Set partitioning
Load more

Recommended publications
  • The Most Common Digital Modulation Techniques Are: Phase-Shift Keying
    Common Digital Modulation Techniques and Pulse Modulation Methods The most common digital modulation techniques are: Phase-shift keying (PSK): o Binary PSK (BPSK), using M=2 symbols o Quadrature PSK (QPSK), using M=4 symbols o 8PSK, using M=8 symbols o 16PSK, using M=16 symbols o Differential PSK (DPSK) o Differential QPSK (DQPSK) o Offset QPSK (OQPSK) o π/4–QPSK Frequency-shift keying (FSK): o Audio frequency-shift keying (AFSK) o Multi-frequency shift keying (M-ary FSK or MFSK) o Dual-tone multi-frequency (DTMF) o Continuous-phase frequency-shift keying (CPFSK) Amplitude-shift keying (ASK) On-off keying (OOK), the most common ASK form o M-ary vestigial sideband modulation, for example 8VSB Quadrature amplitude modulation (QAM) - a combination of PSK and ASK: o Polar modulation like QAM a combination of PSK and ASK.[citation needed] Continuous phase modulation (CPM) methods: o Minimum-shift keying (MSK) o Gaussian minimum-shift keying (GMSK) Orthogonal frequency-division multiplexing (OFDM) modulation: o discrete multitone (DMT) - including adaptive modulation and bit-loading. Wavelet modulation Trellis coded modulation (TCM), also known as trellis modulation Spread-spectrum techniques: o Direct-sequence spread spectrum (DSSS) o Chirp spread spectrum (CSS) according to IEEE 802.15.4a CSS uses pseudo-stochastic coding o Frequency-hopping spread spectrum (FHSS) applies a special scheme for channel release MSK and GMSK are particular cases of continuous phase modulation. Indeed, MSK is a particular case of the sub-family of CPM known as continuous-phase frequency-shift keying (CPFSK) which is defined by a rectangular frequency pulse (i.e.
    [Show full text]
  • Software Defined Acoustic Underwater Modem
    Software Defined Acoustic Underwater Modem Jakob Lindgren April 13, 2011 Abstract Today many types of communication are employed on seagoing vessels, such as radio, satellite and Wi-Fi but only one type of communication is practical for submerged vessels, the acoustic underwater modem. The ”off-the-shelf” modems are sometimes difficult to update and replace, especially on a large submarine. But by separating the hardware from the signal processing and making the software modular more versatility can be achieved. The questions that this thesis are asking are: is it possible to implement the signal processing in software? How small or large should the modules be? What kind of architecture should be used? This thesis shows that it is indeed possible to implement simple algorithms that can isolate a signal and read its content regardless of the hardware configuration. Calculations show that up to 13 kbps can be reached at a range of one kilometer. It is most practical to make the entire physical layer into one module and the size of the system could drastically change the type of architecture used. 1 Preface This Master's thesis from Jakob Lindgren is the final project for receiving the Master's degree in Robotics at M¨alardalenUniversity in V¨aster˚as,Sweden. It covers the basics of digital communication in the underwater channel as well as some simple algorithms for software defined communication. The purpose of this master thesis is to investigate how a software defined acoustic underwater communication can be implemented. This work was done at Saab Underwater Systems in Motala, Sweden, during the autumn term of 2010.
    [Show full text]
  • Etsi En 302 878-2 V1.1.1 (2011-11)
    ETSI EN 302 878-2 V1.1.1 (2011-11) European Standard Access, Terminals, Transmission and Multiplexing (ATTM); Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 2: Physical Layer; DOCSIS 3.0 2 ETSI EN 302 878-2 V1.1.1 (2011-11) Reference DEN/ATTM-003006-2 Keywords access, broadband, cable, data, IP, IPCable, modem ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission.
    [Show full text]
  • Download Article
    IJIRST –International Journal for Innovative Research in Science & Technology| Volume 1 | Issue 8 | January 2015 ISSN (online): 2349-6010 High Speed Low Power Veterbi Decoder For TCM Decoders Using Xilinx T.Mahesh Kumar P.Vijai Bhaskar M.Tech (VLSI) Head of the Department Department of Electronics & Communication Engineering, Department of Electronics & Communication Engineering, JNTUH JNTUH AVN Institute of Engineering & Technology Telangana, India AVN Institute of Engineering & Technology Telangana, India Abstract It is well known that the Viterbi decoder (VD) is the dominant module determining the overall power consumption of TCM decoders. High-speed, low-power design of Viterbi decoders for trellis coded modulation (TCM) systems is presented in this paper. We propose a pre-computation architecture incorporated with -algorithm for VD, which can effectively reduce the power consumption without degrading the decoding speed much. A general solution to derive the optimal pre-computation steps is also given in the paper. Implementation result of a VD for a rate-3/4 convolutional code used in a TCM system shows that compared with the full trellis VD, the precomputation architecture reduces the power consumption by as much as 70% without performance loss, while the degradation in clock speed is negligible. Keywords: Viterbi Decoder, VLSI, Trellis Coded Modulation (TCM). _______________________________________________________________________________________________________ I. INTRODUCTION In telecommunication, trellis modulation (also known as trellis coded modulation, or simply TCM) is a modulation scheme which allows highly efficient transmission of information over band-limited channels such as telephone lines. Trellis modulation was invented by Gottfried Ungerboeck working for IBM in the 1970s, and first described in a conference paper in 1976; but it went largely unnoticed until he published a new detailed exposition in 1982 which achieved sudden widespread recognition.
    [Show full text]
  • DOCSIS 3.0 Physical Layer Specification
    Data-Over-Cable Service Interface Specifications DOCSIS® 3.0 Physical Layer Specification CM-SP-PHYv3.0-C01-171207 CLOSED Notice This DOCSIS specification is the result of a cooperative effort undertaken at the direction of Cable Television Laboratories, Inc. for the benefit of the cable industry and its customers. You may download, copy, distribute, and reference the documents herein only for the purpose of developing products or services in accordance with such documents, and educational use. Except as granted by CableLabs® in a separate written license agreement, no license is granted to modify the documents herein (except via the Engineering Change process), or to use, copy, modify or distribute the documents for any other purpose. This document may contain references to other documents not owned or controlled by CableLabs. Use and understanding of this document may require access to such other documents. Designing, manufacturing, distributing, using, selling, or servicing products, or providing services, based on this document may require intellectual property licenses from third parties for technology referenced in this document. To the extent this document contains or refers to documents of third parties, you agree to abide by the terms of any licenses associated with such third-party documents, including open source licenses, if any. © Cable Television Laboratories, Inc., 2006 - 2017 CM-SP-PHYv3.0-C01-171207 Data-Over-Cable Service Interface Specifications DISCLAIMER This document is furnished on an "AS IS" basis and neither CableLabs nor its members provides any representation or warranty, express or implied, regarding the accuracy, completeness, noninfringement, or fitness for a particular purpose of this document, or any document referenced herein.
    [Show full text]
  • Chapter 1: Modulation Systems
    SYLLABUS: 141304 – ANALOG AND DIGITAL COMMUNICATION L T P C 3 1 0 4 UNIT I FUNDAMENTALS OF ANALOG COMMUNICATION 9 Principles of Amplitude Modulation – AM Envelope – Frequency Spectrum and Bandwidth – Modulation Index and Percent Modulation – AM Voltage Distribution – AM Power Distribution – Angle Modulation – FM and PM Waveforms – Phase Deviation and Modulation Index – Frequency Deviation and Percent Modulation – Frequency Analysis of Angle Modulated Waves – Bandwidth Requirements for Angle Modulated Waves. UNIT II DIGITAL COMMUNICATION 9 Basics – Shannon Limit for Information Capacity – Digital Amplitude Modulation – Frequency Shift Keying – FSK Bit Rate and Baud – FSK Transmitter – BW Consideration of FSK – FSK Receiver – Phase Shift Keying – Binary Phase Shift Keying – QPSK – Quadrature Amplitude Modulation – Bandwidth Efficiency – Carrier Recovery – Squaring Loop – Costas Loop – DPSK. UNIT III DIGITAL TRANSMISSION 9 Basics – Pulse Modulation – PCM – PCM Sampling – Sampling Rate – Signal to Quantization Noise Rate – Companding – Analog and Digital – Percentage Error – Delta Modulation – Adaptive Delta Modulation – Differential Pulse Code Modulation – Pulse Transmission – Intersymbol Interference – Eye Patterns. UNIT IV DATA COMMUNICATIONS 9 Basics – History of Data Communications – Standards Organizations for Data Communication – Data Communication Circuits – Data Communication Codes – Error Control – Error Detection – Error Correction – Data Communication Hardware – Serial and Parallel Interfaces – Data Modems – Asynchronous Modem – Synchronous Modem – Low-Speed Modem – Medium and High Speed Modem – Modem Control. UNIT V SPREAD SPECTRUM AND MULTIPLE ACCESS TECHNIQUES 9 Basics – Pseudo-Noise Sequence – DS Spread Spectrum with Coherent Binary PSK – Processing Gain – FH Spread Spectrum – Multiple Access Techniques – Wireless Communication – TDMA and CDMA in Wireless Communication Systems – Source Coding of Speech for Wireless Communications. L: 45 T: 15 Total: 60 TEXT BOOKS 1.
    [Show full text]
  • Report and Opinion, 2012;4:(1) 62
    Report and Opinion, 2012;4:(1) http://www.sciencepub.net/report Digital Modulation Techniques Evaluation in Distribution Line Carrier system Sh. Javadi 1, M. Hosseini Aliabadi 2 1Department of electrical engineering-Islamic Azad University -Central Tehran Branch [email protected] Abstract- In this paper, different methods of modulation technique applicable in data transferring system over distribution line carries (DLC) system is investigated. Two type of modulation –analogue and digital – is evaluated completely. Different digital techniques such as direct-sequence spread spectrum (DSSS), Frequency-hopping spread spectrum (FHSS), time-hopping spread spectrum (THSS), and chirp spread spectrum (CSS) have been analyzed. The results shows that because of electrical network nature, digital modulation techniques are more useful than analog modulation techniques such as Amplitude modulation (AM) and Angle modulation . [Sh. Javadi, M. Hosseini Aliabadi. Digital Modulation Techniques Evaluation in Distribution Line Carrier system. Report and Opinion 2012; 4(1):62-69]. (ISSN: 1553-9873). http://www.sciencepub.net/report. 11 KEYWORDS- POWER DISTRIBUTION NETWORKS, POWER LINE CARRIER, COMMUNICATION, MODULATION TECHNIQUE Introduction During the last decades, the usage of telecommunications systems has increased rapidly. Because of a permanent necessity for new telecommunications services and additional transmission capacities, there is also a need for the development of new telecommunications networks and transmission technologies. From the economic point of view, telecommunications promise big revenues, motivating large investments in this area. Therefore, there are a large number of communications enterprises that are building up high-speed networks, ensuring the realization of various telecommunications services that can be used worldwide. The direct connection of the customers/subscribers is realized over the access networks, realizing access of a number of subscribers situated within a radius of several hundreds of meters.
    [Show full text]
  • Implementation of Various Digital Modulation Techniques Using Low Cost Components
    IMPLEMENTATION OF VARIOUS DIGITAL MODULATION TECHNIQUES USING LOW COST COMPONENTS Submitted in partial fulfillment of the Degree of Bachelor of Technology May – 2014 Under the Supervision of Mr. Tapan Jain By Abhishek Rustagi (101040) Dhruv Srow (101115) Vivek Raj Singh (101138) DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING JAYPEE UNIVERSITY OF INFORMATION TECHNOLOGY, WAKNAGHAT JAYPEE UNIVERSITY OF INFORMATION TECHNOLOGY (Established under the Act 14 of Legislative Assembly of Himachal Pradesh) Waknaghat, P.O. DomeharBani. Teh. Kandaghat, Distt. Solan- 173234(H.P) Phone: 01792-245367, 245368,245369 Fax-01792-245362 DECLARATION We hereby declare that the work reported in the B. Tech thesis entitled “Implementation of various digital modulation techniques using low cost components” submitted by “Mr. Abhishek Rustagi , Mr. Dhruv Srow and Mr. Vivek Raj Singh” at Jaypee University Of Information Technology, Waknaghat is an authentic record of our work carried out under the supervision of Mr. Tapan Jain. This work has not been submitted partially or wholly to any other university or institution for the award of this or any other degree or diploma. Mr. Abhishek Rustagi Mr. Dhruv Srow Mr. Vivek Raj Singh Department of Electronics and Communication Engineering Jaypee University of Information Technology (JUIT) Waknaghat, Solan – 173234, India II JAYPEE UNIVERSITY OF INFORMATION TECHNOLOGY (Established under the Act 14 of Legislative Assembly of Himachal Pradesh) Waknaghat, P.O. DomeharBani. Teh. Kandaghat, Distt. Solan- 173234(H.P) Phone: 01792-245367, 245368,245369 Fax-01792-245362 CERTIFICATE This is to certify that the work titled “Implementation of various digital modulation techniques using low cost components” submitted by “Mr. Abhishek Rustagi , Mr.
    [Show full text]
  • Performance of High Rate Space-Time Trellis Coded Modulation in Fading Channels
    PERFORMANCE OF HIGH RATE SPACE-TIME TRELLIS CODED MODULATION IN FADING CHANNELS by Sokoya Oludare Ayodeji University ofKwazulu-Natal 2005 Submitted in fulfil/ment ofthe academic requirementfor the degree ofMScEng in the School ofElectrical, Electronic and Computer Engineering, University ofKwaZulu­ Natal,2005 ABSTRACf Future wireless communication systems promise to offer a variety ofmultimedia services which require reliable transmission at high data rates over wireless links. Multiple input multiple output (MIMO) systems have received a great deal of attention because they provide very high data rates for such links. Theoretical studies have shown that the quality provided by MIMO systems can be increased by using space-time codes. Space-time codes combine both space (antenna) and time diversity in the transmitter to increase the efficiency of MIMO system. The three primary approaches, layered space­ time architecture, space-time trellis coding (STTC) and space-time block coding (STBC) represent a way to investigate transmitter-based signal processing for diversity exploitation and interference suppression. The advantages of STBC (i.e. low decoding complexity) and STTC (i.e. TCM encoder structure) can be used to design a high rate space-time trellis coded modulation (HR-STTCM). Most space-time codes designs are based on the assumption of perfect channel state information at the receiver so as to make coherent decoding possible. However, accurate channel estimation requires a long training sequence that lowers spectral efficiency. Part of this dissertation focuses on the performance of HR-STTCM under non-coherent detection where there is imperfect channel state information and also in environment where the channel experiences rapid fading.
    [Show full text]
  • Ep 1130919 A2
    Europäisches Patentamt *EP001130919A2* (19) European Patent Office Office européen des brevets (11) EP 1 130 919 A2 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.7: H04N 7/173, H04L 12/28, 05.09.2001 Bulletin 2001/36 H04J 11/00, H04J 13/02, H04J 3/06, H04B 1/707, (21) Application number: 01104541.6 H04L 5/02, H04L 27/38 (22) Date of filing: 25.07.1996 (84) Designated Contracting States: (72) Inventors: AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC • Rakib, Selim Shlomo, Dr. NL PT SE Cupertino, California 95014 (US) • Azenkot, Yehuda (30) Priority: 25.08.1995 US 519630 San Jose, California 95129 (US) 19.01.1996 US 588650 19.07.1996 US 684243 (74) Representative: Brax, Matti Juhani Berggren Oy Ab, (62) Document number(s) of the earlier application(s) in P.O. Box 16 accordance with Art. 76 EPC: 00101 Helsinki (FI) 96927270.7 / 0 858 695 Remarks: (71) Applicant: Terayon Communication Systems, Inc. This application was filed on 05 - 03 - 2001 as a Santa Clara, CA 95054 (US) divisional application to the application mentioned under INID code 62. (54) Apparatus and method for digital data transmission (57) A method and apparatus for carrying out syn- energy of each channel data over a frame of data trans- chronous co-division multiple access (SCDMA) commu- mitted in a code domain. Frames are synchronized as nication of multiple channels of digital data over a between remote (1164) and central units (1160) using a shared transmission media (1162).
    [Show full text]
  • Chapter 3 Digital Transmission Fundamentals
    Chapter 3 Digital Transmission Fundamentals Digital Representation of Information Why Digital Communications? Digital Representation of Analog Signals Characterization of Communication Channels Fundamental Limits in Digital Transmission Line Coding Modems and Digital Modulation Properties of Media and Digital Transmission Systems Error Detection and Correction Digital Networks z Digital transmission enables networks to support many services TV E-mail Telephone Questions of Interest z How long will it take to transmit a message? z How many bits are in the message (text, image)? z How fast does the network/system transfer information? z Can a network/system handle a voice (video) call? z How many bits/second does voice/video require? At what quality? z How long will it take to transmit a message without errors? z How are errors introduced? z How are errors detected and corrected? z What transmission speed is possible over radio, copper cables, fiber, infrared, …? Chapter 3 Digital Transmission Fundamentals Digital Representation of Information Bits, numbers, information z Bit: number with value 0 or 1 z n bits: digital representation for 0, 1, … , 2n z Byte or Octet, n = 8 z Computer word, n = 16, 32, or 64 z n bits allows enumeration of 2n possibilities z n-bit field in a header z n-bit representation of a voice sample z Message consisting of n bits z The number of bits required to represent a message is a measure of its information content z More bits → More content Block vs. Stream Information Block Stream z Information that occurs z
    [Show full text]
  • Modulation of Signals
    International Journal of Research (IJR) e-ISSN: 2348-6848, p- ISSN: 2348-795X Volume 2, Issue 4, April 2015 Available at http://internationaljournalofresearch.org Modulation of Signals Akshay dutt (16195); Anosh Justin (16199) & Gautam saini (16211) Department of ECE Dronacharya College of Engineering Khentawas, Farrukh Nagar-123506 Gurgaon, Haryana Email- [email protected] ABSTRACT This paper addresses the technique of rapidly A modem (from modulator–demodulator) can updating the weights of an adaptive filter to perform both operations. cancel non-stationary interference. This method The aim of digital modulation is to transfer is used, for example, in radar systems that a digital bit stream over an receive coherent multipath interference, known analog bandpass channel, for example over as "hot clutter" or "terrain scattered jamming". the public switched telephone network (where We develop a framework for understanding how a bandpass filter limits the frequency range to this rapid weight updating (inadvertently) 300–3400 Hz), or over a limited radio frequency modulates signals. Two principal types band. of modulation are studied: random modulations induced by finite-length The aim of analog modulation is to transfer training sets and non- an analog baseband (or lowpass) signal, for randommodulations induced by the coherence of example an audio signal or TV signal, over an the interference. Our framework is then used to analog bandpass channel at a different frequency, assess the impact of these modulations on the for example over a limited radio frequency band overall performance of various well-known or a cable TV network channel. jammer multipath mitigation algorithms. Several Analog and digital modulation techniques for controlling this modulation are facilitate frequency division multiplexing (FDM), proposed.
    [Show full text]