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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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公开(公告)号：DE69904026D1
公开(公告)日：2003-01-02
申请号：DE69904026
申请日：1999-01-28
Applicant: ST MICROELECTRONICS NV
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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：DE69807486D1
公开(公告)日：2002-10-02
申请号：DE69807486
申请日：1998-06-10
Applicant: ST MICROELECTRONICS NV
Inventor： OLOFSSON SVEN-RUNE , JOHANSSON JOACHIM , ISAKSSON MIKAEL , OEHMAN HANS , BENGTSSON DANIEL , OLSSON LENNART , ISAKSSON ANDERS , OEKVIST GOERAN , LJUNGGREN LIS-MARI , LUNDBERG HANS , STEFANSSON TOMAS , BAHLENBERG GUNNAR , HAKANSSON SIVERT , JOHANSSON MAGNUS
Abstract: An arrangement for synchronization of nodes in VDSL-systems, or more exactly, synchronization of optical VDSL-nodes which share a common part of a cable in the access network between subscribers and a local station. A time synchronization is provided towards an external system, for instance GPS, which gives a time reference by which the different nodes can be synchronized. The synchronization reduces the near end cross-talk between the VDSL-systems in the different nodes. Preferably, each respective node includes a receiver for a synchronization signal and an internal oscillator with high stability to deliver a stable clock signal.
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Patent Agency Ranking
公开(公告)号：DE69717122T2
公开(公告)日：2003-08-21
申请号：DE69717122
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 , OEDLING PER
Abstract: A multi-carrier transmission system such as a DMT system. Channel information is transmitted between two transceivers using a plurality of sub-carriers modulated with symbols, each of which represents a multiplicity of bits. Each of the transceivers includes a receiver and a transmitter in which a fixed maximum value was determined for the number of bits for each symbol and in which the system is adapted to determine the bit capacity per symbol of each of the plurality of sub-carriers and to increase the number of bits represented by a symbol transmitted over those sub-carriers having a capacity less than a fixed maximum value to the maximum value by the addition of channel coding bits. The fixed maximum value for the number of bits for each symbol may be determined on the basis of the bit capacity of that one of the sub-carriers having the highest theoretical bit capacity may be at least as large as the theoretical bit capacity.
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公开(公告)号：DE69904026T2
公开(公告)日：2003-07-17
申请号：DE69904026
申请日：1999-01-28
Applicant: ST MICROELECTRONICS NV
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公开(公告)号：AT232034T
公开(公告)日：2003-02-15
申请号：AT97939276
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：DE69717121D1
公开(公告)日：2002-12-19
申请号：DE69717121
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: PCT No. PCT/SE97/01461 Sec. 371 Date Jun. 14, 1999 Sec. 102(e) Date Jun. 14, 1999 PCT Filed Sep. 1, 1997 PCT Pub. No. WO98/10556 PCT Pub. Date Mar. 12, 1998A multi-carrier transmission system, particularly a discrete multi-tone (DMT) system. Data is transmitted between two transceivers using a plurality of carriers. The frequency bandwidth of the system is divided between the plurality of carriers. The transmission system is adapted for operation in a heterogeneous network including a number of subscriber equipments having different channel characteristics and coexisting on the same cable. The length of cable for each subscriber terminal varies in relation to its respective location. The transmission system includes an allocation device for allocating the traffic of subscriber equipments having a shorter length of cable to tones starting from a higher frequency band of the system bandwidth.
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公开(公告)号：AT228286T
公开(公告)日：2002-12-15
申请号：AT97939279
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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