Showing papers on "Orthogonal frequency-division multiplexing published in 1992"
Patent•
31 Mar 1992TL;DR: In this article, a first frame of information is multiplexed over a number of wideband frequency bands at a first transceiver, and the information transmitted to a second transceiver.
Abstract: A method for allowing a number of wireless transceivers to exchange information (data, voice or video) with each other. A first frame of information is multiplexed over a number of wideband frequency bands at a first transceiver, and the information transmitted to a second transceiver. The information is received and processed at the second transceiver. The information is differentially encoded using phase shift keying. In addition, after a pre-selected time interval, the first transceiver may transmit again. During the preselected time interval, the second transceiver may exchange information with another transceiver in a time duplex fashion. The processing of the signal at the second transceiver may include estimating the phase differential of the transmitted signal and pre-distorting the transmitted signal. A transceiver includes an encoder for encoding information, a wideband frequency division multiplexer for multiplexing the information onto wideband frequency voice channels, and a local oscillator for upconverting the multiplexed information. The apparatus may include a processor for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission.
489 citations
Book•
01 Jan 1992
TL;DR: This book discusses components of a Digital Communication System, Signals, Systems, Modulation, and Noise, and Design Examples and System Tradeoffs, and some Commonly Used Modulation Schemes.
Abstract: (NOTE: Most chapters begin with an Introduction and conclude with Summary, References, and Problems.) 1. Introduction to Digital Data Transmission. Components of a Digital Communication System. Communications Channel Modeling. Communication Link Power Calculations. Driving Forces in Communications. Computer Use in Communication System Analysis and Design. Preview of the Book. 2. Signals, Systems, Modulation, and Noise: Overview. Review of Signal and Linear System Theory. Basic Analog Modulation Techniques. Complex Envelope Representation of Bandpass Signals and Systems. Signal Distortion and Filtering. Practical Filter Types and Characteristics. Sampling Theory. Random Processes. Computer Generation of Random Variables. 3. Basic Digital Communication Systems. The Binary Digital Communications Problem. Signaling through Bandlimited Channels. Equalization in Digital Data Transmission. A Digital Communication System Simulation Example. Noise Effects in Pulse Code Modulation. 4. Signal-Space Methods in Digital Data Transmission. Optimum Receiver Principals in Terms of Vector Spaces. Performance Analysis of Coherent Digital Signaling Schemes. Signaling Schemes Not Requiring Coherent References at the Receiver. Comparison of Digital Modulation Systems. Comparison of M-ary Digital Modulation Schemes on Power and Bandwidth-Equivalent Bases. Some Commonly Used Modulation Schemes. Design Examples and System Tradeoffs. Multi-h Continuous Phase Modulation. Orthogonal Frequency Division Multiplexing. 5. Channel Degradations in Digital Communications. Synchronization in Communication Systems. The Effects of Slow Signal Fading in Communicative Systems. Diagnostic Tools for Communication System Design. 6. Fundamentals of Information Theory and Block Coding. Basic Concepts of Information Theory. Fundamentals of Block Coding. Coding Performance in Slow Fading Channels. 7. Fundamentals of Convolutional Coding. Basic Concepts. The Viterbi Algorithm. Good Convolutional Codes and Their Performance. Other Topics. 8. Fundamentals of Repeat Request Systems. General Considerations. Three ARQ Strategies. Codes for Error Detection. 9. Spread-Spectrum Systems. Two Communication Problems. Types of Spread-Spectrum Systems. Complex-Envelope Representation of Spread Spectrum. Generation and Properties of Pseudorandom Sequences. Synchronization of Spread-Spectrum Systems. Performance of Spread-Spectrum Systems in Jamming Environments. Performance in Multiple User Environments. Multiuser Detection. Examples of Spread-Spectrum Systems. 10. Introduction to Cellular Radio Communications. Frequency Reuse. Channel Models. Mitigation Techniques for the Multipath Fading Channel. System Design and Performance Prediction. Advanced Mobile Phone Service. Global System for Mobile Communications. Code Division Multiple Access. Recommended Further Reading. 11. Satellite Communications. Allocation of a Satellite Transmission Resource. Link Power Budget Analysis. Examples of Link Power Budget Calculations. Low- and Medium-Earth Orbit Voice Messaging Satellite Systems. Appendix A. Probability and Random Variables, Probability Theory. Random Variables, Probability Density Functions, and Averages. Characteristic Function and Probability Generating Function. Transformations of Random Variables. Central Limit Theorem. Appendix B. Characterization of Internally Generated Noise. Appendix C. Attenuation of Radio-Wave Propagation by Atmospheric Gases and Rain. Appendix D. Generation of Coherent References. Description of Phase Noise and Its Properties. Phase-Lock Loop Models and Characteristics of Operation. Frequency Synthesis. Appendix E. Gaussian Probability Function. Appendix F. Mathematical Tables. The Sinc Function. Trigonometric Identities. Indefinite Integrals. Definite Integrals. Series Expansions. Fourier Transform Theorems. Fourier Transform Pairs. Index.
244 citations
TL;DR: It is shown that OFDM/FM works well with switching diversity because OFDM can average out the transients created by switching between antennas and it is found that the independent error assumption can be used to predict the distribution of the number of errors in a word.
Abstract: For pt.I see ibid., vol.39, no.5, p.783-93 (1991). The performance of an orthogonal frequency-division multiplexing (OFDM)/frequency modulation (FM) system for data communication over Rayleigh-fading mobile radio channels was analyzed in pt.I. The effects of forward error correction, switching diversity, automatic gain control (AGC), and squelch are studied. It is shown that OFDM/FM works well with switching diversity because OFDM can average out the transients created by switching between antennas. It is also found that the independent error assumption can be used to predict the distribution of the number of errors in a word. The use of squelch produced a small (about 1 dB) performance improvement, whereas the use of AGC provided negligible improvement. >
53 citations
TL;DR: In this article, the Fabry-Perot etalon was used to provide multiple and evenly spaced absolute frequency references, which can be used for close spacing or coherent applications where channel separation and reproducibility is critical between transmitter and receiver.
Abstract: The frequency locking of a large number of lasers in OFDM applications requires an equally large number of stable references at predictable frequencies. The authors present a technique to lock a Fabry-Perot etalon on an atomic reference to provide multiple and evenly spaced absolute frequency references. Absolute etalon spacing is calibrated by matching two atomic references with two corresponding etalon modes. To maintain long-term stability in channel spacing, the etalon is locked to an atomic resonance using an electrical feedback loop to control mirror separation. This technique can be used for close spacing or coherent applications where channel separation and reproducibility is critical between transmitter and receiver. >
45 citations
Patent•
11 Feb 1992
TL;DR: In this article, a method of binary encoding the N points of a constellation corresponding to the discrete positions, in amplitude and in phase, associated with the encoding of binary words in the case of a multicarrier modulation of OFDM type (Orthogonal Frequency Division Multiplexing) of a digitized signal was proposed.
Abstract: The present invention relates to a method of binary encoding the N points of a constellation corresponding to the discrete positions, in amplitude and in phase, associated with the encoding of binary words in the case of a multicarrier modulation of OFDM type (Orthogonal Frequency Division Multiplexing) of a digitized signal. According to the method, two adjacent points of the constellation correspond to binary words which differ from one another by at most two bits. The present invention applies in particular to digital television.
34 citations
06 Dec 1992
TL;DR: The concept of the TCM-OFDM system for terrestrial digital TV broadcasting and a system configuration that needs no carrier recovery at the receiver and gives simulation results of the bit error rate performances under various receiving conditions are described.
Abstract: OFDM (orthogonal frequency division multiplexing) is regarded as an excellent digital modulation method for various future digital broadcasting systems, including digital audio broadcasting (DAB). The scope of applications of the OFDM can be further expanded by combining it with TCM (trellis coded modulation). This TCM-OFDM system can transmit a much larger number of data than conventional OFDM, causing almost no degradation of bit error rate performance within the same frequency bandwidth. The concept of the TCM-OFDM system for terrestrial digital TV broadcasting and a system configuration that needs no carrier recovery at the receiver and gives simulation results of the bit error rate performances under various receiving conditions are described. >
22 citations
Patent•
24 Nov 1992TL;DR: In this article, a frame oriented digital data transmission method is proposed, where data are transmitted in the zero symbol of the frame of the modulation method provided in the COFDM (Coded Orthogonal Frequency Division Multiplex) which is provided in digital radio.
Abstract: A frame oriented, digital data transmission method wherein data are transmitted in the zero symbol of the frame of the modulation method provided in the COFDM (Coded Orthogonal Frequency Division Multiplex) which is provided in digital radio. This allows for further digital data to be independently transmitted outside of the actual digital multiplex signal. The method can also be used, among other things, for transmitter identification in common frequency networks.
9 citations
Patent•
01 Dec 1992
TL;DR: In this paper, a multicarrier modulation of the orthogonal frequency division multiplexing (OFDM) type using N orthogonality channels is described, where the channels are divided into two, N/2 channels corresponding to a first frequency band and a second frequency band.
Abstract: Process for the emission of a signal digitized according to a multicarrier modulation of the orthogonal frequency division multiplexing (OFDM) type using N orthogonal channels. According to the invention, the channels are divided into two, N/2 channels corresponding to a first frequency band being transmitted by a first emission path (3A, 4A, 5A, 6A, 7A) according to a first polarization while the remaining N/2 channels are brought to the first frequency band and transmitted by a second emission path (3B, 4B, 5B, 6B, 7B) according to a second polarization crossed in relation to the first. Application especially in digital high definition television.
7 citations
Patent•
24 Nov 1992
TL;DR: In this article, a frame-oriented, digital data transmission process is disclosed, where data are transmitted in the null symbol of the frame of a digital radio broadcasting COFDM modulation process, thus allowing further digital data to be independently transmitted in addition to the actual digital multiplex signal.
Abstract: A frame-oriented, digital data transmission process is disclosed. Data are transmitted in the null symbol of the frame of a digital radio broadcasting COFDM (coded orthogonal frequency division multiplex) modulation process, thus allowing further digital data to be independently transmitted in addition to the actual digital multiplex signal. This is useful, among others, to identify the transmitters in a common frequency broadcasting network.
7 citations
Patent•
31 Jan 1992
TL;DR: In this article, the effective transmitted data are interleaved by an interleaving matrix and inputted to a serial/parallel converting circuit while switched with the amplitude and phase reference data stored in a fixed reference data memory under the control of a switching control signal.
Abstract: PURPOSE:To receive data on a reception side without regenerating carriers by periodically sending out amplitude and phase reference data of the respective carriers at a determined position in a frame consisting of plural transmitted symbols. CONSTITUTION:The effective transmitted data are interleaved by an interleaving matrix 101 and inputted to a serial/parallel converting circuit 103 while switched with the amplitude and phase reference data stored in a fixed reference data memory 102 under the control of a switching control signal. The serial-parallel converting circuit 103 converts the data consisting of bits, sent with one transmitted symbol, into parallel data, which are inputted to an orthogonal frequency division multiplexed digital signal(OFDM) modulator 104. The OFDM modulator 104 generates the time base waveform of the base band by inverse discrete Fourier transformation and inputs it to a parallel-serial converting circuit 105, and the data are converted into serial data, which is further converted into an OFDM signal of radio frequency through a D/A converting circuit 106, a low-pass filter, and a frequency converting circuit 108.
7 citations
TL;DR: In this article, a solution which only requires nearest-neighbor interconnections in the frequency domain is proposed and discussed for OFDM systems based on multistage interconnection networks with space-frequency interstage patterns.
Abstract: For OFDM systems based on multistage interconnection networks with space-frequency interstage patterns the number of crossed channels and the interconnection length in the frequency domain is aimed to be a minimum. A solution which only requires nearest-neighbor interconnections in the frequency domain is proposed and discussed.
Patent•
11 Feb 1992
TL;DR: In this paper, a method for the binary coding of N points of a constellation corresponding to the discrete positions in amplitude and phase associated to the coding of binary words in the case of a multicarrier modulation of the OFDM type (Orthogonal Frequency Division Multiplexing) of a digitalized signal was proposed.
Abstract: The present invention relates to a method for the binary coding of N points of a constellation corresponding to the discrete positions in amplitude and phase associated to the coding of binary words in the case of a multicarrier modulation of the OFDM type (Orthogonal Frequency Division Multiplexing) of a digitalized signal. According to the method, two adjacent points of the constellation correspond to binary words which differ from each other by two bits at the most. The present invention applies particularly to digital television.