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21.发明申请
公开(公告)号：WO9810547A3
公开(公告)日：1998-05-07
申请号：PCT/SE9701452
申请日：1997-09-01
Applicant: TELIA AB , 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 AAKE , BENGTSSON DANIEL , HAAKANSSON SIWERT , WEN YE
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-AAKE , BENGTSSON DANIEL , HAAKANSSON SIWERT , WEN YE
CPC classification number: H04L27/2675 , H04L27/2656 , H04L27/2657
Abstract: In a multi-carrier 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. The present invention provides an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier.
Abstract translation: 在诸如DMT系统的多载波系统中，接收机必须能够恢复非常准确地与发射机采样时钟同步的采样时钟。 典型地，通过使用保留载波（导频载波）来实现同步，该导频载波以固定相位进行传输。 接收器采样时钟然后锁相到导频载波。 帧定时可以通过使用相关技术来恢复。 本发明提供了一种恢复采样时钟并将采样时钟锁相到导频载波的改进方法。
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公开(公告)号：NO20002139D0
公开(公告)日：2000-04-27
申请号：NO20002139
申请日：2000-04-27
Applicant: TELIA AB
Inventor： BAHLENBERG GUNNAR , BENGTSSON DANIEL , HOKANSSON SIWERT , ISAKSSON ANDERS , ISAKSSON LARS-KE , ISAKSSON MIKAEL , HANSSON MAGNUS , LAHTI MAURTIZ , LJUNGGREN LIS-MARIE , LUNDBERG HANS , NORDSTROEM TOMAS , OLSSON LENNART , OLOFSSON SVEN-RUNE , STEFANSSON TOMAS , IMAN HANS , IKVIST GOERAN , IDLING PER , DENTGEN PETRA , SJOEBERG FRANCK
Abstract: The hybrid circuit can be used to substantially reduce near echo signals. The circuit includes a balanced 2-wire to 4-wire hybrid for interconnecting a two wire receive path and a two wire transmit path to a two wire transmission line. The two wire receive path connects the balanced hybrid to an A/D converter and the two wire transmit path connects a D/A converter to the balanced hybrid. The two wire receive path contains a filter, dimensioned to remove signals transmitted from the D/A converter. The invention is particularly adapted for use with FDD and OFDD.
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公开(公告)号：SE9704009L
公开(公告)日：1999-05-04
申请号：SE9704009
申请日：1997-11-03
Applicant: TELIA AB
Inventor： OLSSON LENNART , BAHLENBERG K-G , BENGTSSON DANIEL , HAAKANSSON SIWERT , ISAKSSON ANDERS , ISAKSSON L-AA , ISAKSSON MIKAEL , JOHANSSON MAGNUS , LATHI MAURITZ , LJUNGGREN KARIN L-M , LUNDBERG HANS , NORDSTROEM TOMAS , OLOFSSON S-R , STEFANSSON TOMAS , OEHMAN HANS , OEKVIST S G , OEDLING PER , DENTGEN PETRA , SJOEBERG FRANK
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公开(公告)号：NO990767D0
公开(公告)日：1999-02-19
申请号：NO990767
申请日：1999-02-19
Applicant: TELIA AB
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY , OLSSON LENNART , STEFANSSON TOMAS , IHMAN HANS , BAHLENBERG GUNNAR , ISAKSSON ANDERS , IKVIST GOERAN , LJUNGGREN LIS-MARIE , NORDSTROEM TOMAS , ISAKSSON LARS-AAKE , BENGTSSON DANIEL , HOKANSSON SIWERT , WEN YE
Abstract: A multi-carrier transmission system has a plurality of transceivers, each having a receiver and a transmitter. Data is transmitted between the transceivers by modulating the data onto a multiplicity of carrier waves in the form of multi-bit symbols, wherein each carrier wave constitutes a channel, and wherein the number of bits per symbol (the bit loading), varies between channels and, within a channel, with time, so that each channel has associated therewith a bit loading parameter. In operation, the multi-carrier system is adapted to synchronously update, at the transceivers, the bit loading parameters associated with each channel by transmission of data over a control channel, in that the control channel is established, at system start-up, on a predetermined one of the multiplicity of carrier waves whose identity is known to the transceivers, and in that the control channel is, after start-up, changed from the predetermined channel to a further channel, selected by the first transceiver on the basis of channel characteristics.
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公开(公告)号：SE9703630L
公开(公告)日：1998-09-04
申请号：SE9703630
申请日：1997-10-06
Applicant: TELIA AB
Inventor： OLSSON LENNART , BENGTSSON DANIEL , HAAKANSSON SIWERT , ISAKSSON ANDERS , ISAKSSON LARS-AAKE , ISAKSSON MIKAEL , JOHANSSON MAGNUS , LATHI MAURITZ , LJUNGREN KARIN LIS-MARIE , LUNDBERG HANS , NORDSTROEM TOMAS , OLOFSSON SVEN-RUNE , STEFANSSON TOMAS , OEHMAN HANS , OEKVIST SVEN GOERAN , BAHLENBERG KJELL-GUNNAR
Abstract: A mechanism for achieving frame synchronization in the frequency domain. In order to synchronize a receiver with a transmitter, on signal acquisition, the interval in which orthogonality exists is determined. Once this has been achieved, an argument function is calculated from the received frame. This argument function can then be used to improve the synchronization. This system is particularly suitable for use in ADSL and VDSL modems which can be used to give broad band access over copper networks. It is also relevant to broad band transmission in mobile and semi-mobile systems for transmission over radio channels.
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Patent Agency Ranking
公开(公告)号：SE506689C2
公开(公告)日：1998-02-02
申请号：SE9603198
申请日：1996-09-02
Applicant: TELIA AB
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY ERLAND , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG KJELL GUNNAR , ISAKSSON ANDERS IMANUEL , OEKVIST SVEN GOERAN , LJUNGGREN KARIN LIS-MARI , NORDSTROEM TOMAS , ISAKSSON LARS-AAKE , BENGTSSON DANIEL , YE WEN , HAAKANSSON SIWERT
IPC: H04L20060101 , H04L5/06 , H04L27/26
Abstract: The system includes an allocating unit which allocates the traffic of subscriber equipments having a shorter length of cable to tones starting from a higher frequency band. Interference in a lower frequency band are reduced and a better signal to noise ratio is achieved on tones above a system noise level to subscriber equipments with relatively longer lengths of cable. Preferably, the usable frequency band of the system bandwidth for subscriber equipments having relatively longer lengths of cable is determined by the noise level of the system. The allocation unit operates in accordance with a tone allocation algorithm.
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公开(公告)号：SE506638C2
公开(公告)日：1998-01-26
申请号：SE9603191
申请日：1996-09-02
Applicant: TELIA AB
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY ERLAND , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG KJELL GUNNAR , ISAKSSON ANDERS IMANUEL , OEKVIST SVEN GOERAN , LJUNGGREN KARIN LIS-MARI , NORDSTROEM TOMAS , ISAKSSON LARS-AAKE , BENGTSSON DANIEL , YE WEN , HAAKANSSON SIWERT
IPC: H04L20060101 , H04L5/06 , H04L27/26
Abstract: The receiver has a receiver sampling clock synchronised with a transmitter sampling clock by extracting timing data from a pilot carrier on which a known sequence of symbols is transmitted. The receiver has a control channel mechanism receiving a control channel over which data relating to changes in dynamic transmission parameters are transmitted. A correlation mechanism extracts timing data from the pilot carrier and uniquely identifies a symbol at which the change in dynamic transmission parameters is effected. The multicarrier transmission system is a discrete multitone (DMT) transmission system and a based VDSL system.
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公开(公告)号：SE506635C2
公开(公告)日：1998-01-26
申请号：SE9603188
申请日：1996-09-02
Applicant: TELIA AB
Inventor： ISAKSSON MIKAEL , JOHANSSON MAGNUS , TONVALL HARRY E , OLSSON LENNART , STEFANSSON TOMAS , OEHMAN HANS , BAHLENBERG KJELL GUNNAR , ISAKSSON ANDERS I , OEKVIST SVEN GOERAN , LJUNGGREN KARIN L-M , NORDSTROEM TOMAS , ISAKSSON LARS-AAKE , BENGTSSON DANIEL , YE WEN , HAAKANSSON SIWERT
IPC: H04L20060101 , H04L5/06 , H04L27/26
Abstract: The receiver includes a back-coupling coil which controls an oscillator device. The back coupling coil uses a back coupling signal which represents an argument value of the pilot carrier wave. The back coupling signal is obtained from an approximation of an argument for a complex number which represents the pilot carrier wave. The approximation maintains a full resolution of the complex number and the back-coupling coil controls the oscillator device so that the pilot argument tends to approach zero. The back-coupling coil compensates for channel effects. The oscillator device is a voltage controlled crystal oscillator and the multi-carrier wave transmission system is of the discrete multiple tone (MT) type or a MT-based very high bit rate digital subscriber line system.
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公开(公告)号：SE9704497D0
公开(公告)日：1997-12-03
申请号：SE9704497
申请日：1997-12-03
Applicant: TELIA AB
Inventor： OLSSON LENNART , BAHLENBERG KJELL-GUNNAR , BENGTSSON DANIEL , HAAKANSSOON SIWERT , ISAKSSON ANDERS , ISAKSSON MIKAEL , JOHANSSON MAGNUS , LJUNGGREN KARIN L-M , LUNDBERG HANS , NORDSTROEM TOMAS , OLOFSSON SVEN-RUNE , STEFANSSON TOMAS , OEHMAN HANS , OEKVIST SVEN GOERAN
Abstract: The present invention simplifies known data scramblers by making use of the synchronisation frames, normally used for measuring channel characteristics, as a source of pseudo-random data which can be combined with incoming user data. The present invention has particular application to multi-carrier transmission systems which employ DMT, or OFDM. Many of these transmission systems send known data, usually referred to as synchronisation frames, to measure channel characteristics such as signal to noise ratio. The known data contained in a synchronisation frame is selected to have a suitable statistical distribution, e.g. pseudo-random. In the data scrambler of the present invention, user data bits are combined with the known synchronisation frame data using an exclusive-OR function. This results in a statistically and computationally efficient scrambling of the user data.
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公开(公告)号：SE9703629D0
公开(公告)日：1997-10-06
申请号：SE9703629
申请日：1997-10-06
Applicant: TELIA AB
Inventor： OLSSON LENART , BAHLENBERG KJELL-GUNNAR , BENGTSSON DANIEL , HAAKANSSON SIWERT , ISAKSSON ANDERS , ISAKSSON LARS-AAKE , ISAKSSON MIKAEL , JOHANSSON MAGNUS , LATHI MAURITZ , LJUNGREN KARIN LIS-MARIE , LUNDBERG HANS , NORDSTROEM TOMAS , OLOFSSON SVEN-RUNE , STEFANSSON TOMAS , OEHMAN HANS , OEKVIST SVEN 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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