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公开(公告)号：DE69719336D1
公开(公告)日：2003-04-03
申请号：DE69719336
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
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公开(公告)号：AT233452T
公开(公告)日：2003-03-15
申请号：AT97939278
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
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公开(公告)号：AT233451T
公开(公告)日：2003-03-15
申请号：AT97937935
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. Such systems place high demands on the synchronization of the receiver with the transmitter. The maximum permitted deviation from exact synchronization is usually a small fraction of a sampling interval. A reserve carrier, the pilot carrier, which is given a fixed phase, is usually used as the reference to achieve this high accuracy. The receiver sampling clock oscillator is phase locked to the pilot carrier. It is therefore necessary to estimate the phase of the pilot carrier. Using a bandpass filter to recover the pilot carrier, regardless of the frame structure of the DMT signal, does not eliminate the influence of neighboring carriers on the pilot carrier.
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公开(公告)号：DE69718799D1
公开(公告)日：2003-03-06
申请号：DE69718799
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system, such as a DMT system. A receiver must be able to recover a sampling clock that is very accurately synchronized to a transmitter sampling clock. Typically, synchronization is achieved by using a reserved carrier, the pilot carrier, which is transmitted with a fixed phase. The receiver sampling clock is then phase locked to the pilot carrier. Frame timing can be recovered by using a correlation technique. Thus an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier is provided.
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公开(公告)号：DE69810251D1
公开(公告)日：2003-01-30
申请号：DE69810251
申请日：1998-02-27
Applicant: ST MICROELECTRONICS NV
Inventor： OLSSON LENNART , BAHLENBERG GUNNAR , BENGTSSON DANIEL , HAKANSSON SIWERT , ISAKSSON ANDERS , ISAKSSON LARS-AKE , ISAKSSON MIKAEL , JOHANSSON MAGNUS , LAHTI MAURITZ , LJUNGGREN LIS-MARIE , LUNDBERG HANS , NORDSTROEM TOMAS , OLOFSSON SVEN-RUNE , STEFANSSON TOMAS , OEMAN HANS , OEKVIST GOERAN
Abstract: With OFDM systems the frequency domain data is the Fourier transform of the received time domain OFDM frames. The time domain frames must be sampled, at the receiver, in synchronism with the transmitter, so that each received frame contains data from only a single transmitted frame. It is vital for this synchronism to be maintained in order to maintain the orthogonality of the frames. A typical multi-carrier system, of the OFDM type, which uses a cyclic prefix permits orthogonality to be maintained when there is a small deviation from exact frame synchronisation. Because the signalling interval includes both an entire frame and the cyclic prefix, which is a repetition of part of the frame, a frame sampled within the signalling interval will contain data from only one frame. Since the signalling interval is greater than the frame period, this gives some leeway in frame alignment. In a multi-carrier system of the OFDM type, an adaptive channel equalizer, operating in the frequency domain, is often used. The internal parameters in such an equalizer contain, in addition to information about the characteristics of the channel, information which can be interpreted as the time deviation between the sampling clocks of the transmitter and the receiver. The present invention utilizes this information to control the sampling clock of the receiver in a more robust way than has previously been possible with known techniques. The present invention is particularly suitable for use in ADSL and VDSL modems which can be used to give broadband access over copper networks. The invention is also of relevance to broadband transmission in mobile and semi-mobile systems for transmission over the radio channels.
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Patent Agency Ranking
公开(公告)号：DE69717285D1
公开(公告)日：2003-01-02
申请号：DE69717285
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system such as a DMT based VDSL system. The system uses orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. This estimate includes digital receiver and transmitter units with the receiver unit including a symbol detection unit. This system is adapted to determine a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point. It compares the parameter with an upper lower limit and if the parameter is outside the limits, changes the constellation used to modulate the carrier to a neighboring constellation. The symbol detection unit may be used to determine a parameter such as the ratio d2/sigma2, where d is the shortest distance between neighboring constellations, sigma is a standard deviation and sigma2 is the variance of the deviations of the input and output signal values of the symbol detection unit.
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公开(公告)号：AT227912T
公开(公告)日：2002-11-15
申请号：AT97937936
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAEKANSSON SIWERT , WEN YE
Abstract: A two-way multi-carrier transmission system, such as a DMT system. If there are dynamic changes in the transmission parameters, synchronization must be maintained between the transmitter and the receiver when the transmission parameters changed. The first stage of such a process requires that the changes of parameter be notified by one transceiver to others involved in an active communication process over a slow transmission channel such as the control channel. Subsequently, the synchronization transceiver is adjusted simultaneously, i.e., from a predetermined DMT symbol. Such adjustments in time synchronization must be achieved with a minimum of overhead.
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公开(公告)号：DE69723563D1
公开(公告)日：2003-08-21
申请号：DE69723563
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of a plurality of bits per carrier and symbol. The system uses some method for the determination of an inverse channel model to be used in the equalization process. In the frequency domain, this is normally based on an estimate of the channel attenuation and phase for each carrier. A simplified method of equalization is provided which uses data at the symbol carrier input and output to adaptively estimate an inverse channel model.
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公开(公告)号：AT245324T
公开(公告)日：2003-08-15
申请号：AT97939280
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of a plurality of bits per carrier and symbol. The system uses some method for the determination of an inverse channel model to be used in the equalization process. In the frequency domain, this is normally based on an estimate of the channel attenuation and phase for each carrier. A simplified method of equalization is provided which uses data at the symbol carrier input and output to adaptively estimate an inverse channel model.
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公开(公告)号：DE69722415D1
公开(公告)日：2003-07-03
申请号：DE69722415
申请日：1997-09-01
Applicant: ST MICROELECTRONICS NV
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AKE , BENGTSSON DANIEL , HAKANSSON SIWERT , WEN YE
Abstract: In certain types ol transmission system using nQ,1M it may be desirable to use a control applications in muIticarrier snrstems with variable bitloading it is particularly desirible that the control channel data be separable from user data when the value of n. i.e the bitloading. or constellation identifier are unknown. Binary data is transmitted using nQAM modulation. The binary data comprises both user data and cointro,l clata. This means that a control channel is superimposed on a user data channel within the same nQAM constellation. Separation of said control data is lacilitated by arranging control data points to have either unique phase, or unique amplitude, values. These unique values are not employed for user data points.
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