EP0974209A1 - Systeme et methode pour conferer une forme spectrale a des signaux de donnees transmis - Google Patents

Systeme et methode pour conferer une forme spectrale a des signaux de donnees transmis

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Publication number
EP0974209A1
EP0974209A1 EP98914478A EP98914478A EP0974209A1 EP 0974209 A1 EP0974209 A1 EP 0974209A1 EP 98914478 A EP98914478 A EP 98914478A EP 98914478 A EP98914478 A EP 98914478A EP 0974209 A1 EP0974209 A1 EP 0974209A1
Authority
EP
European Patent Office
Prior art keywords
sign
symbol
bits
encoded
information bits
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98914478A
Other languages
German (de)
English (en)
Inventor
M. Vedat Eyuboglu
Dae-Young Kim
Chien-Cheng Tung
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Motorola Solutions Inc
Original Assignee
Motorola Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motorola Inc filed Critical Motorola Inc
Publication of EP0974209A1 publication Critical patent/EP0974209A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
    • H04L25/40—Transmitting circuits; Receiving circuits
    • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
    • H04L25/4917—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes
    • H04L25/4927—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes using levels matched to the quantisation levels of the channel

Definitions

  • This invention relates to high-speed data communications and more particularly to a system and method for spectrally shaping transmitted data signals.
  • the public switched telephone network consists of a digital backbone network and analog local loops that connect end users to this backbone.
  • the analog signal sent by the local user is digitized at the local central office and converted into a 64 kbit/s bit stream which is carried across the digital backbone network and then converted back to analog at the remote central office for transmission to the end user over the remote local loop.
  • Dial-up modems e.g. V.34 modems, communicate over the PSTN by modulating the digital information into an analog signal for transmission.
  • the digital-to-analog conversion process at the entry point to the digital backbone introduces quantization noise which limits the data transmission speed to around 30 kbit s.
  • the encoded data is first mapped into octet ⁇ for transmission at a rate of 8000 octets per second. Then, in the end user's central office, the octets are converted into corresponding symbols in the D/A converter. The resulting ⁇ kHz sequence of symbols is passed through a low pass filter (LPF) and transmitted over the analog loop to the end user's analog PCM modem.
  • LPF low pass filter
  • the output of the D/A converter can be viewed as a sequence of impulses each having an amplitude corresponding to one of the D/A levels.
  • the analog PCM modem recovers the original information by first detecting which symbols were transmitted, and then inverse mapping these symbols to obtain an estimate of the original digital information.
  • PCM there is a need for a scheme that can shape the spectrum of the signal transmitted from the D/A converter. Further, there is a need for a spectral shaping scheme that is applicable to various types of transmission technologies in addition to PCM.
  • FIG. 1 is a simplified block diagram of a typical telephone company central office
  • FIG. 2 is plot of the frequency spectrum of the symbols, y. , output from the ⁇ -law to linear converter of FIG, 1 and the spectral shape of the low pass filter of FIG. 1;
  • FIG. 3 is a plot of a portion of two frequency spectrums each having a null at DC, wherein one spectrum falls off to zero very abruptly at DC and the other spectrum falls off more gradually;
  • FIG. 4 is schematic block diagram of a transmitter of a central site digital PCM modem configured according to this invention.
  • FIG. 5 is a schematic block diagram of a receiver of an end user analog PCM modem configured according to this invention.
  • FIG. 6 is a schematic block diagram of the sign bit encoder of the transmitter depicted in FIG. 4;
  • FIG. 7 is a schematic block diagram of the coset representative generator depicted in FIG. 6;
  • FIG. 8 is schematic block diagram of the symbol sign bit selector of FIG. 6;
  • FIG. 9 is a trellis diagram which represents a convolutional code
  • FIG. 10 is a flow diagram illustrating the generalized logic for the symbol sign bit selector as depicted in FIG. 8;
  • FIG. 11 is a schematic block diagram of the sign bit decoder depicted in FIG. 5; and
  • FIG. 1 is a schematic block diagram of the present invention utilized as a precoder in an upstream PCM transmitter.
  • the present invention involves a system and method for spectrally shaping transmitted data signals that is generally applicable to various data transmission technologies.
  • the invention is described herein with regard to a PCM transmission system.
  • PCM PCM transmission system
  • FIGS. 1 and 2 illustrate the presence of energy near DC in the signals transmitted to an end user's analog PCM modem over an analog loop
  • FIG. 1 a portion of a typical telephone central office 10 on a PSTN which receives at input 12 ⁇ -law octets transmitted from a central site digital PCM modem (not shown) directly attached to the digital portion of the telephone system.
  • the octets are converted by a D/A converter, also known as a ⁇ -law to linear converter 1 , to a sequence of symbols, y k . Each of the symbols corresponds to one of 255 ⁇ -law levels.
  • the symbols are output over line 16 to a low pass filter (LPF) 18 which outputs over analog loop 20 to the end user analog PCM mode 's receiver a filtered analog signal s(t).
  • LPF low pass filter
  • the analog signal is demodulated and decoded by the receiving modem, which outputs a digital bit stream.
  • the digital bit stream is an estimate of the originally transmitted data.
  • the sequence of symbols, y ⁇ , on line 16 from ⁇ -law to linear converter 14 has a flat frequency response 22, FIG.2.
  • DC null 28 is depicted in FIG. 3.
  • the running digital sum (RDS) of the transmitted symbols, y ⁇ (namely, the algebraic sum of all previously transmitted levels) must be maintained near zero.
  • the shape of the spectrum around DC null 28 can vary from a relatively shallow sloped spectrum 30 to a spectrum 32 which falls off very abruptly at DC. The sharpness of the null depends on how tightly the RDS is controlled.
  • the present invention encodes the digital data being transmitted in a manner that maintains the RDS near zero. This creates a spectral null at DC thereby reducing the non-linear distortion caused by transformer saturation. More generally, the invention may also be used to encode digital data being transmitted to shape the spectrum of the transmitted signal, as desired.
  • Transmitter 40 in a digital PCM modem receives a serial digital bit stream 42 from data terminal equipment (not shown), such as a personal computer, and encodes the received bits into octets 44 for transmission over digital network 46.
  • Serial bit stream 42 is converted to parallel format by serial to parallel converter 48.
  • the transmitting/encoding scheme of this invention is based on an o-symbol data frame, where k represents the data frame (time) index. For example, there may be 2, 3, 4. 5 or 6 symbols transmitted per data frame. The symbols transmitted correspond to ⁇ -law constellation points selected to represent the information bits.
  • serial to parallel converter 48 outputs (n-r)+m information bits, where ris the number of redundancy bits.
  • the number of redundancy bits as specified in the V.90 standard may be 0, 1, 2 or 3. It should be noted that for the remainder of the description lowercase variables denote scalar quantities, while uppercase variables denote matrices. Also, row vectors are represented by a bold lowercase variables and all indices start from 0, e.g., x. - ( w , x ,).
  • n-rb ' its, labeled bits v ⁇ represent the information carried through sign bits (the sign information bits) and the m bits, labeled bits u. , represent the information carried through the magnitudes (the magnitude information bits).
  • the number of bits, m can be determined by choosing m to satisfy the following:
  • M is the number of positive constellation points for the i-th symbol in a data frame. This process is more fully described in the V.90 standard.
  • the m magnitude information bits, u. are provided to magnitude mapper 50 which maps the m bits to n symbol magnitudes, g v by a mapping scheme such as a shell mapping, as described in the ITU V.34 standard, or by a modulus conversion, described in the ITU V.90 standard.
  • the magnitudes to which the magnitude information bits are mapped are the magnitudes of the ⁇ -law points used as constellation points in transmitting the information bits.
  • the remaining information bits in the data frame, the sign information bits v ., are provided to sign bit encoder 52 which generates ⁇ sign bits, s k , (encoded symbol sign bits) as described in detail below.
  • the n symbol magnitudes, g k , and the n sign bits, «be, are provided to signal point selector 54 and are combined to form n signed symbols .
  • the ⁇ signed symbols y. are then provided to octet converter 56 which selects an octet corresponding to each of the signed symbols and transmits the octets to digital network 46.
  • the octet converter which converts the signed symbols to a form compatible with the digital portion of the PSTN, may not be used and the signal point selector would output the signed symbols directly to the network.
  • the octets 44' exiting digital network 46 (possibly modified by digital impairments in the network) are received by central office (CO) 60.
  • the octets 44* are converted into symbols by a D/A converter in CO 60 and transmitted as an ⁇ kHz sequence of levels over the analog loop 62 to receiver 64 of an end user analog PCM modem.
  • the analog levels are received by receiver front end 66, which digitizes the analog levels, performs timing recovery, equalization and symbol decision.
  • Receiver front end 66 outputs received symbols, y k , in serial format to serial to parallel converter 68 which converts the serial symbols into frames of n parallel signed symbols y k .
  • the n parallel signed symbols y. are provided to magnitude and sign extractor 70 which extracts symbol magnitudes g. and sign bits s. from y k .
  • Symbol magnitudes g. are provided to magnitude demapper 72, e.g. a modulus conversion demapper, to recover the magnitude information bits u k . Since the demapping process is understood by persons skilled in the art, it will not be explained herein.
  • the sign bits ⁇ . . are provided to sign bit decoder 74 to recover the sign information bits v., as described below.
  • the decoded information bits may then be further processed and provided to data terminal equipment, such as a personal computer.
  • Sign bit encoder 52 is depicted in more detail in FIG. 6.
  • the sign information bits v k are provided to coset representative generator 80 which generates for each frame n coset representative sign bits t k and provides them to symbol sign bit selector 82.
  • the n coset representative sign bits t k during each frame define a coset representative element tor a defined convolut ' tonal code, G(D), used by symbol sign bit selector 82 and the entire sequence of co ⁇ et representative sign bits t(D) collectively define a coset representative for the convolutional code.
  • the n coset representative sign bits f also identify a coset of the convolutional code which contains candidates of encoded symbol sign bits, as described in more detail below.
  • symbol sign bit selector 62 modifies coset representative sign bits ⁇ by EXCLUSIVE OR'ing the bits with valid convolutional code sequences defined by a trellis diagram, such as the trellis diagram depicted in FIG. 9 and described below, to fomn the candidates of encoded symbol sign bits. These candidates are elements of the coset Identified by the coset representative sign bits. With the symbol magnitudes, symbol sign bit selector 82 selects for each frame the candidate of encoded symbol sign b * ⁇ ts. ⁇ fc , from the candidates of encoded symbol sign bits that produces the desired spectral shape and provides those sign bits to signal point selector 54, FIG. 4.
  • Coset representative generator 80 is depleted in more detail in FIG. 7 to include differential encoder 84 and matrix block 86. Noise on the data channel might cause a polarity Inversion by affecting the transmitted sign bits.
  • differential decoder 132 FIG. 11
  • D is the frame delay, which is the delay based on the frame (time) index k.
  • symbol sign bit selector 82 includes selection controller 88 which receives the n coset representative sign bits t_ each frame from coset representative generator 80 and n symbol magnitudes from magnitude mapper 50, FIG. 4 and outputs encoded symbol sign brts t s h , for each frame.
  • Selection controller 88 combines the candidates of encoded symbol sign bits with the magnitudes to form encoded signed symbol candidates, which are provided to filter 90.
  • Filter 90 calculates a metric referred to herein as a running filter sum (RFS), described below, for each candidate and provides them to selection controller 88 which selects the encoded symbol sign bits associated with the encoded signed symbol candidate that minimizes RFS.
  • RFS running filter sum
  • Selection controller 88 modifies the ⁇ coset representative sign bits t k per frame by EXCLUSIVE-ORing the coset representative sign bits with valid code sequences of the convolutional code.
  • the convolutional code is the set of possible sequences defined by a trellis diagram and the valid code sequences are the sequences that do not violate the constraints of the trellis diagram.
  • selection controller 88 modifies the ⁇ coset representative sign bits t k by EXCLUSIVE-OR'ing them with certain convolutional code sequences according to the constraints of trellis diagram 100.
  • the convolutional code sequences in this example are as follows:
  • Each of the candidates is also an element of a coset of the convolutional code identified by the coset representative sign bits (or the element of the coset representative). Then, each candidate is combined with the symbol magnitudes to form encoded signed symbol candidates which are provided to fitter 90, FIG. 8, where the RFS for each is calculated and returned to selection controller 88. Selection controller 88 outputs the encoded symbol sign bits for frame j that minimize the RFS.
  • the current state Q ⁇ together with the convolutional code sequence of the encoded symbol sign bits selected for frame k are used to determine the next state by following the constraints of trellis diagram 100. For example, if candidate l, ⁇ B was selected for frame k, the state of selection controller 88 at the beginning of frame is 1.
  • symbol sign bit selector 82 may use the symbol magnitudes produced by the magnitude mapper 50, FIG. 4, and the coset representative sign bits for the current frame and for future frames to decide which encoded symbol sign bits achieve the best spectral shaping.
  • the V.90 standard specifies that up to three frames in the future may be used depending on the amount of look-ahead delay negotiated during startup.
  • the spectral shaping metric RFS based on a filter transfer function h(D), is computed for all possible paths (or candidate sequences) through the trellis diagram up to the look-ahead delay or depth ⁇ by filter 90, and the selection controller selects the encoded symbol sign bits associated with the candidate sequence for frame k that produces the smallest RFS.
  • the coset representative sign bits are EXCLUSIVE-OR'ed with each of the valid coda sequences to form candidates of encoded symbol sign bits.
  • the coset representative sign bits for each frame k and k+1 are EXCLUSIVE-OR'ed with the valid code sequences in each path of the trellis diagram thereby forming candidate sequences.
  • the candidate sequences in this example are the following four sequences: ⁇ 1) ( f, ⁇ A, t kt , ® A); 2) ( J, ® A, *,., ⁇ B); 3) ( t k ⁇ B, f trip t , ⁇ C); and 4) ( t k ⁇ B, t M ⁇ D) ⁇ .
  • T e RFS for each sequence is determined and the candidate encoded symbol sign bits for frame k in the determined sequence is chosen.
  • step 120 describes the operation of symbol sign bit selector 82.
  • selection controller 88 generates the candidates (or candidate sequences in the case of look-ahead) of encoded symbol sign bits by modifying the coset representative sign bits according to the trellis diagram. Then, in step 124 selection controller combines the symbol magnitudes and the candidates of encoded symbol sign bits to form encoded signed symbol candidates (or candidate sequences) and provides them to filter 90.
  • filter 90 determines the RFS for each candidate (or candidate sequence) and provides the RFS for each candidate (or candidate sequence) to selection controller 88.
  • step 12B selection controller 88 chooses the candidate of encoded symbol sign bits (or candidate sequence) that minimizes RFS and sends the encoded symbol sign bits.
  • this invention may utilize various convolutional codes, G(D), which are represented by different trellis diagrams and different convolutional code sequences.
  • G(D) convolutional codes
  • the extension to various convolutional codes and code sequences in light of the description herein will be straightforward to persons of ordinary skill in the art.
  • the spectral shaping scheme shapes the spectrum of the analog signal transmitted from the D/A converter in CO 60, FIG. 5, by setting the response of filter 90, FIG. 8, to achieve a desired spectral shape and by minimizing the RFS.
  • the response, h(d), of filter 90, which defines the desired spectral shape may be expressed as follows:
  • RFS on a symbol-by-symbol basis may be calculated as follows: RFS ⁇ ⁇ b ⁇ - ⁇ RFS, ⁇ (4)
  • the RFS is the running digital sum (RDS) and the response, h(D), of filter 90 is expressed as follows:
  • filter 90 calculates the RDS of transmitted signed symbols y. at symbol time . as follows:
  • the RDS is calculated as follows:
  • Sign bit decoder 74 in receiver 64, FIG. 5. is shown in FIG 11 to include a matrix block 110.
  • matrix block 110 the sign bits ⁇ . are multiplied (in modulo 2) (i.e., filtered) by matrix H ⁇ tolM to recover the differentially encoded sign information bits v k '.
  • the matrix H ⁇ is designed so that the decision error in v. due to error in the received sign signal a, will not propagate more than one frame, This is because H ⁇ is a finite impulse response (FIR) type of matrix and there is only a single delay.
  • FIR finite impulse response
  • / ⁇ although., represents the states, Q ⁇ , of the trellis diagram and ⁇ represents the branches or paths taken through the trellis diagram.
  • the four convolutional code sequences A-D can be mapped to the r consult.,, r t representation as follows:
  • each set of ⁇ sign bits generated by the different valid code sequences may be used to produce the same decoded information.
  • the set of ⁇ sign bits that minimize the RFS/RDS can be selected to perform spectral shaping as desired.
  • the spectral shaping scheme according to this invention can also be used in an equalization context as in the transmitter of an analog PCM modem used for upstream PCM transmission to perform precodlng.
  • the response h(D) represents the channel response between the transmitting modem and the analog-to-digital (A/D) converter in the central office (CO) line card, and typically includes the effects of filtering in the transmitting modem front-end, the analog local loop and the CO line card.
  • a channel output sequence x(n) (z(n) with prefiltering) can be generated that produces a sequence y(D) at the A D converter input whose signal points mimic the A/D quantization levels.
  • the channel response h(D) will be determined either by the receiving modem or jointly by the transmitting and receiving modems based on channel measurements made during modem start-up, and then during data transmission the transmitting mode will map the incoming bits into the transmission sequence x(D), which after passing through the channel are converted to the channel output sequence y(D).
  • the channel response h(D) is usually chosen to be minimum phase, which is easily accomplished, for example through additional filtering in the transmitter.
  • Transmitter 40' is a transmitter in an analog PCM modem which is capable of upstream PCM transmission.
  • Transmitter 40' uses the spectral shaping scheme of this invention to precede, using precoder 140, the incoming data bit stream 42'.
  • One type of PCM upstream precodi ⁇ g (referred to as one-dimensional precoding which precodes on a per symbol basis) is described in detail in US Patent App,, Attorney Docket No. CX0 ⁇ 6044P02, entitled Device and Method for Precoding Data Signals, filed December 29, 1997, having inventors M. Vedat Eyuboglu, Pierre A. Humblet; and Daeyoung Kim.
  • Precoder 140 performs multi-dimensional precoding, i.e. it precodes symbols on a per frame basis.
  • the present implementation differs from one- dimensional precoding, but the concept Is analogous to the one-dimensional case and reference may be made to the above co-pending application for further detail.
  • Precoder 140 includes a serial to parallel converter 48', magnitude mapper 50', sign bit encoder 52' and a signal point selector 54'. These components are configured and operate as do the components with like numbers in FIG. 4 with minor modifications. For example, the operation of the sign bit encoder is modified to perform precoding, as described below, and the signal point selector outputs n precoded levels, xicide per frame corresponding to the signed symbols, y kt instead of the signed symbols themselves. The n preceded levels, x, are provided to parallel to serial converter 142 which outputs the precoded levels in serial form to prefilter 1 4. Prefilter 144 filters the levels and outputs the filtered levels to digital to analog converter 146 which in turn transmits precoded analog levels over analog channel 148.
  • the channel modifies the preceded levels , x k , and ideally produces levels corresponding to the signed symbols, whatsoever at the quantizer in central office (CO) 150.
  • the precoder selects precoded levels, x v that produce levels corresponding to the desired signed symbols, y admir, at the quantizer by accounting for the response of analog channel 148, or more precisely a target channel response, h(n).
  • the target channel response, h(n) is equal to g(n), the response of prefilter 144, convolved with c(n), the response of analog channel 148, where n is the symbol time index and h(0)-1 . That relationship can be expressed as follows:
  • equation (15) can be simplified as follows:
  • a timing interpolation filter which ensures that the symbols are transmitted in synchronism with the network clock.
  • This timing interpolation filter will typically be driven by the clock recovery circuit used in the downstream receiver.
  • the transmitter may also include a linear filter which is primarily responsible for iimiting the transmission bandwidth to about 4 kHz and to provide the necessary prefiftering which would make the overall channel response h(D) minimum phase.
  • trellis coding to increase noise immunity.
  • the trellis coding techniques described in the application referred to above, entitled System and Device for, and Method of, Communicating According to a Trellis Code of Baseband Signals Chosen from a Fixed Set of Baseband Signal Points, filed November 14. 1996, US Apl. Ser. No, 08/749040 (Attorney Docket No CX096050) can be used. That application is incorporated herein in its entirety by reference. The operation of the system is essentially unaffected by trellis coding.
  • this invention may be embodied in software and/or firmware, which may be stored on a computer useable medium, such as a computer disk or memory chip.
  • the invention may also take the form of a computer data signal embodied in a carrier wave, such as when the invention is embodied in software/firmware, which is electrically transmitted, for example, over the Internet.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Probability & Statistics with Applications (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
  • Error Detection And Correction (AREA)
  • Dc Digital Transmission (AREA)
  • Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)

Abstract

On décrit un système qui, dans un réseau (46), transmet d'un émetteur (40) vers un récepteur des bits d'information numérique codés en un nombre prédéfini de symboles signés par trame ayant une forme spectrale voulue. Les bits d'information numérique sont divisés en un premier nombre préétabli de bits d'information d'amplitude et en un deuxième nombre préétabli de bits d'information de signe par trame. L'émetteur comprend un dispositif de topographie mémoire d'amplitude (50) pour configurer les bits d'information d'amplitude relativement au nombre prédéfini d'amplitudes de symboles, un codeur de bit de signe (52) pour coder les bits d'information de signe dans le nombre préétabli de bits de signe de symbole codés par trame, et un sélecteur de point de signal (54) qui réagit au dispositif de topographie mémoire d'amplitude et au codeur de bits de signe en combinant les amplitudes de symboles et les bits de signe de symbole pour former le nombre prédéfini de symboles signés transmis par trame.
EP98914478A 1997-04-08 1998-04-03 Systeme et methode pour conferer une forme spectrale a des signaux de donnees transmis Withdrawn EP0974209A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US4282697P 1997-04-08 1997-04-08
US42826P 1997-04-08
US5231998A 1998-03-31 1998-03-31
US52319 1998-03-31
PCT/US1998/006650 WO1998045970A1 (fr) 1997-04-08 1998-04-03 Systeme et methode pour conferer une forme spectrale a des signaux de donnees transmis

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EP0974209A1 true EP0974209A1 (fr) 2000-01-26

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EP (1) EP0974209A1 (fr)
JP (1) JP2002501693A (fr)
KR (1) KR20010006101A (fr)
CN (1) CN1252195A (fr)
AU (1) AU6882498A (fr)
BR (1) BR9815183A (fr)
CA (1) CA2285073A1 (fr)
EA (1) EA001872B1 (fr)
IL (1) IL131921A0 (fr)
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US5999109A (en) 1997-06-09 1999-12-07 3Com Corporation Frame-based spectral shaping method and apparatus
EP1129554B1 (fr) * 1998-11-14 2004-02-04 STMicroelectronics Asia Pacific Pte Ltd. Procedes de mise en oeuvre efficace de la mise en forme spectrale sur la base du treillis avec anticipation
US6778611B1 (en) 1999-08-31 2004-08-17 Broadcom Corporation Subdimensional single-carrier modulation
EP1219085B1 (fr) * 1999-08-31 2010-02-10 Broadcom Corporation Modulation par porteuse unique sous-dimensionnelle
US6418170B1 (en) * 2000-02-07 2002-07-09 Motorola, Inc. Method and apparatus for achieving 180° phase invariant transmission in a PCM modem system
WO2001059946A1 (fr) 2000-02-10 2001-08-16 Telogy Networks, Inc. Precodeur generalise pour le canal amont d'un modem en bande telephonique
US6973579B2 (en) 2002-05-07 2005-12-06 Interdigital Technology Corporation Generation of user equipment identification specific scrambling code for the high speed shared control channel
TWI411298B (zh) * 2009-03-05 2013-10-01 Realtek Semiconductor Corp Frequency conversion device and conversion method and filter thereof
US11418220B2 (en) 2020-03-20 2022-08-16 Huawei Technologies Co., Ltd. Method, system, and apparatus for a segmented polarization-adjusted convolutional (PAC) code

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US5040191A (en) * 1987-02-24 1991-08-13 Codex Corporation Partial response channel signaling systems
US5150381A (en) * 1989-02-16 1992-09-22 Codex Corporation Trellis shaping for modulation systems
US5548615A (en) * 1993-05-03 1996-08-20 At&T Corp. Methods and apparatus for rotationally invariant multilevel coding
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IL131921A0 (en) 2001-03-19
KR20010006101A (ko) 2001-01-26
TW445733B (en) 2001-07-11
EA001872B1 (ru) 2001-10-22
CN1252195A (zh) 2000-05-03
EA199900807A1 (ru) 2000-06-26
AU6882498A (en) 1998-10-30
WO1998045970A1 (fr) 1998-10-15
JP2002501693A (ja) 2002-01-15
CA2285073A1 (fr) 1998-10-15
BR9815183A (pt) 2000-10-10

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