EP1593243A2 - Method for the continuous estimation of the equalizer coefficients for wire-bound transmission systems - Google Patents
Method for the continuous estimation of the equalizer coefficients for wire-bound transmission systemsInfo
- Publication number
- EP1593243A2 EP1593243A2 EP02791618A EP02791618A EP1593243A2 EP 1593243 A2 EP1593243 A2 EP 1593243A2 EP 02791618 A EP02791618 A EP 02791618A EP 02791618 A EP02791618 A EP 02791618A EP 1593243 A2 EP1593243 A2 EP 1593243A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- receiving
- transmitting
- receiving device
- equalizer
- signals
- 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- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/14—Two-way operation using the same type of signal, i.e. duplex
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
- H04L2025/03414—Multicarrier
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
- H04L2025/0342—QAM
Definitions
- the invention relates to a receiving or transmitting / receiving device according to the preamble of claim 1, a data communication system with such a receiving device, and a data reception method according to the preamble of claim 15. one or more transmitting or transmitting / receiving devices, from which transmission signals e.g. are transmitted via twisted pair lines to one or more receiving or transmitting / receiving devices, and vice versa.
- EWSD Electronic Dialing System Digital
- a subscriber line e.g. a twisted pair line is connected, via which the modulated transmission signals e.g. are transmitted to a modem provided on a subscriber end connection.
- Corresponding transmission signals are also sent out by the subscriber end connection modem (for example via a further twisted pair line) and received by the corresponding end exchange modem.
- the data communication between the modems can e.g. based on POTS (Piain Old Phone Service), ISDN (Integrated Services Digital Network), or xDSL (x Digital Subscriber Line) data transmission protocols, e.g. by means of ADSL data transmission or in accordance with the ITU G.992.1 (G.dmt) or ITU G.992.2 (G.Lite) standards.
- POTS Purain Old Phone Service
- ISDN Integrated Services Digital Network
- xDSL x Digital Subscriber Line
- a QAM data transmission method For the transmission of data via the xDSL frequency bands, e.g. a QAM data transmission method can be used.
- a cosine oscillation can be used in a certain frequency band, the frequency of which is e.g. lies in the middle of the corresponding frequency band.
- each bit is associated with (eg using a phase star) a cosine oscillation 'specific amplitude and phase.
- the respectively transmitted bit or the respectively transmitted bit sequence can then be determined in the receiving device from the amplitude and phase of the respectively received cosine oscillation.
- DSL data transmission methods in addition to the actual user data, e.g. also transmit synchronization data.
- Synchronization data is transmitted during a predetermined period of time defined in the DSL standard (i.e. during the so-called synchronization data frame or frames). In the period following the synchronization frame, which is divided into 68 subsections
- the synchronization data frame and the subsequent 68 user data frames together form a DSL super or meta frame comprising a total of 69 frames.
- a synchronization data bit sequence identical to the synchronization data bit sequence transmitted by the respective transmission / reception device is previously stored in the (further) transmission / reception device communicating with the respective transmission / reception device.
- the data bit sequence received in each case is compared with the previously stored synchronization data bit sequence.
- the bit sequence received in each case is to be assigned to a synchronization data frame or a user data frame. As a result, a temporal coordination of the DSL data transmission between the transmitting and the receiving transceiver can be achieved.
- DSL data transmission over a specific twisted pair line can lead to distortion of the originally transmitted signal for a variety of reasons.
- an (adjustable) equalizer device is provided on the respective receiving device, in which the received signal is equalized.
- training sequences are transmitted from the respective transmission device during the initialization phase. These are known in the respective receiving device and are compared there with the actually received (disturbed) training sequences. From this, the (current) channel distortions can be determined in a manner known per se.
- the above-mentioned equalizer device can then be set accordingly so that the received signals are equalized (as well as possible). Since the distortion properties of the respective transmission channel change continuously, the equalizer device is readjusted at regular intervals.
- statistical methods are used during the actual user data transmission to determine the (possibly changed) distortion properties of the transmission channel, e.g. statistical gradient algorithms, for example an LMS algorithm.
- the object of the invention is to provide a new type of receiving or transmitting / receiving device, a new type of data communication system with such a receiving or transmitting / receiving device, and a new type of data receiving method.
- a receiving device or a transmitting / receiving device which is set up in such a way that it can receive transmission signals modulated via a transmission channel from a transmitting or a further transmitting / receiving device, synchronization data being transmitted with the aid of the transmission signals , which are used for synchronization of the receiving device, and wherein the receiving or transmitting / receiving device has an equalizing device for equalizing the received or derived signals, characterized in that the same transmission signals with which the synchronization data are transmitted which are also used in the receiving device for setting the equalizer device.
- the equalizer device can be set relatively quickly and with relatively high accuracy, in particular even when the initialization phase of the receiving device has already ended (i.e. during the actual useful data transmission).
- the good equalization of the received or derived signals leads to a reduced bit error rate compared to the prior art.
- the synchronization data advantageously contain a synchronization data bit sequence which is compared to synchronize the receiving or transmitting / receiving device with a bit sequence previously stored in a storage device of the receiving or transmitting / receiving device.
- the transmission signals which are used to synchronize the receiving or transmitting / receiving device and to set the equalizer device are transmitted during a synchronization frame, and the actual user data are transmitted during a (user) data frame.
- Figure la is a schematic representation of a phase star used for the transmission of useful and reference / synchronization data
- FIG. 1b shows a bit sequence assignment table used in the phase star shown in FIG.
- Figure lc is a schematic representation of a data communication system with transceivers according to the present invention
- Figure ld is a schematic representation of the frequency bands used by a transceiver according to the invention for POTS or ISDN and for DSL data transmission;
- FIG. 2 shows a useful and reference
- Synchronization data transmission uses cosine oscillation
- FIG. 3 shows a further cosine oscillation used for the transmission of user and reference / synchronization data
- FIG. 4 shows a third for use and reference
- FIG. 5 shows a schematic illustration of a useful and reference
- Figure 6 is a schematic representation of the structure and operation of the transceiver shown in Figure lc.
- FIG. 9 An example of a data communication system 9 according to the present invention is shown in FIG.
- the data communication system 9 has a terminal exchange 11 connected to a telephone network (here: the public telephone network 10) (here: an electronic digital dialing system). tal or EWSD).
- a telephone network here: the public telephone network 10) (here: an electronic digital dialing system). tal or EWSD).
- a plurality of transmission / reception devices 15 are provided, which are each connected to transmission / reception devices 14 via subscriber lines 12, for example twisted-pair lines, which are arranged in subscriber end connection devices 13.
- the twisted pair lines each consist of two wires 12a, 12b. Differential or symmetrical signals are used for data transmission via the respective wire pairs.
- the data communication between the transmitting / receiving devices 15 provided in the terminal exchange 11 and the transmitting / receiving devices 14 of the subscriber end connection devices 13 takes place by means of POTS (Piain Old Telephone Service) or ISDN (Integrated Services Digital)
- a plurality of frequency bands (bins) lying in a frequency range 16 are used in the xDSL data transmission.
- 16a, 16b, 16c, 16d, 16e used (here: M different frequency bands) that lie above a frequency fl.
- the frequency range 17 below the frequency fl is used for conventional POTS or ISDN voice data transmission.
- fl is approximately 25 kHz
- ISDN data transmission approximately 130 kHz.
- a QAM method for example, can be used for DSL data transmission between corresponding end-of-office transmitter / receiver devices 15 and subscriber transmitter / receiver devices 14 (and vice versa).
- cosine carrier vibrations are used, the frequencies of which can be in the middle of the corresponding frequency band 16a, 16b, 16c, 16d, 16e, for example.
- the phase star 1 shown in FIG. 1 a can be used, for example, to encode data (for example user data and also reference / synchronization data) in a cosine oscillation.
- the reference / synchronization data in the exemplary embodiment explained here serve to set an equalizer device 22 and to synchronize the useful data transmission.
- phase star 1 has three concentric circles, each of which is assigned an oscillation amplitude AI, A2, A3 of a certain height, as shown below.
- a total of 16 points a, b, c, d, f (or - in other words - 16 symbols a, b, c, d, f) lying in the complex number plane are arranged on these circles, each of which here one of 16 different ones Sequences of 4 bits is assigned.
- FIG. 1 a In a corresponding manner, according to FIG. 1 a, four further points c are located on the outermost circle assigned to the third amplitude A3 at corresponding angles ⁇ l, ⁇ 2, ⁇ 3 and ⁇ 4 of 45 °, 135 °, 225 ° and 315 °, f (or symbols c, f) according to the assignment table 2 shown in FIG. 1b each assigned the bit sequence "1100", "1111", "0000" or "0011".
- the remaining bit sequences (1101”, “1110”, “1000”, “1011”, “0100”, “Olli”, “0001”, “0010”) are assigned to 8 points (or symbols), which are on the middle , the second amplitude A2 associated circle, in each case at angles ⁇ 5, ⁇ 6, ⁇ 7, ⁇ 8, ⁇ 9, ⁇ lO, ⁇ ll or ⁇ l2 of approx. 20 °, 70 °, 110 °, 160 °, 200 °, 250 °, 290 ° or 340 °.
- All cosine vibrations 3, 4, 5 have - depending on the frequency band used in each case - a specific, constant frequency, as explained above, each lying in the middle of the corresponding frequency band 16a, 16b, 16c, 16d, 16e.
- Each cosine vibration 3, 4, 5 identifies a certain one of the above.
- Bit sequences specifically via the level of the oscillation amplitude AI, A2, A3, and via the phase shift ⁇ of the respective oscillation 3, 4, 5 with respect to a basic clock running synchronously in the respective transmitting / receiving devices 14, 15 or with respect to one of the respective ones Transceiver 15 emitted pilot tone oscillation.
- the amplitude AI, A2, A3 used in each case corresponds to the amplitude which is assigned to the circle of the phase star 1 shown in FIG. 1 a on which the point or the symbol a, b, c, d, e, f lies, to which the is assigned to each bit sequence to be transmitted.
- phase shift ⁇ of the respective cosine oscillation 3, 4, 5 is selected such that it corresponds to the above-mentioned angle ⁇ l, ⁇ 2, ⁇ 3, ⁇ 4, ⁇ 5, ⁇ 6, ⁇ 7, ⁇ 8, ⁇ 9, ⁇ lO, ⁇ ll or ⁇ l2 of the respective assigned to the bit sequence to be transmitted th point or symbol a, b, c, d, e, f in phase star 1 corresponds.
- each frequency band 16a, 16b, 16c, 16d, 16d the data transmission takes place at predetermined time periods, i.e. within certain frames.
- a plurality (here: 69) of different frames la, 2a, 3a, ..., 69a, each lasting a predetermined period of time are combined to form a meta or superframe 6 (of which a large one) - rer, according to how the meta-frame 6 follows the meta-frame, etc.).
- the meta frames 6 can e.g. each have a duration of 10-25 ms, in particular approximately 17 ms.
- the first frame la of the meta frame 6 represents a so-called synchronization frame, followed by several (here: 68) data frames 2a, 3a, ..., 69a.
- the data frames 2a, 3a,... 69a serve to transmit useful data and (during an initialization phase - ie before the actual (useful) data transmission begins) reference data.
- the reference data transmitted during the initialization phase are used to set the equalizer 22.
- the synchronization frame or the first frame la serves for the transmission of synchronization data.
- these are also used as reference data, in particular for setting, e.g. for readjustment, the equalizer 22.
- FIG. 6 shows a - schematic - illustration of the structure and the mode of operation of the transmitting / receiving device 14 shown in FIG. 1c.
- the transmitting / receiving device 15 arranged in the terminal exchange 11 is constructed accordingly and has corresponding functionalities, such as the transmitting / receiving device 14 on the subscriber line side shown in FIG. 6.
- the analog signals received via the subscriber line 12 from the terminal exchange 11 are converted in a (not shown) analog-digital conversion device into (serial) digital signals which are output on a line 7.
- Conversion device 8 supplied, and there converted into corresponding parallel, digital signals.
- the parallel digital signals are fed via a line bundle 18 to a Fourier transformation device 19.
- DFT discrete Fourier transform
- the amplitudes A k and phases ⁇ k (or the M (complex) symbol values Y k ) are transmitted to an equalization device 22 via a line bundle 20 consisting of several different lines, and the equalized signals (represented here by M ( Complex) symbol values Y'k, vector Y ') for further signal processing are then fed via a line bundle 27 consisting of several further lines to an evaluation device (not shown).
- DSL data transmission over the twisted-pair line 12 can lead to distortions of the originally transmitted signals for a variety of reasons.
- the (adjustable) equalizer device 22 serves to compensate for the distortions.
- the equalizer 22 can have, for example, a plurality of digital filter devices, each with one (or more, for example cascaded) digital filters.
- the filter coefficients of the digital filters can be set externally, for example by applying corresponding control signals to corresponding control lines in a line bundle 28.
- the above-mentioned equalizer 22 in particular the filter coefficients of the digital filters contained therein, are set so that the received signals are equalized (as well as possible), in particular in such a way that for each of the above-mentioned (complex) symbol values output by the equalizer 22 Y ' k - viewed in the frequency domain - the following formula applies:
- FEQ k or H _1 k is the inverse of the estimated (channel or channel frequency) for the kth channel or the kth frequency band 16a, 16b, 16c, 16d, 16e (the total of M channels or M frequency bands). ) Transfer function H k .
- the equalizer 22 or the filter coefficients are e.g. in a manner known per se on the basis of the reference data transmitted during the data frames 2a, 3a, ..., 69a.
- the equalization device 22 Since the distortion properties of the respective transmission channel change continuously, the equalization device 22 is readjusted at regular intervals after the initialization phase. The adjustment or readjustment of the equalizer device 22 or the filter coefficients is carried out, as will be explained in detail below, on the basis of the reference / synchronization data transmitted during the synchronization frame 1 a.
- the reference / synchronization data transmitted during the synchronization frame 1 a can also be used during the initialization phase for setting the equalizer device 22 or the filter coefficients.
- the (equalized) signals (ie the above-mentioned M (complex) symbol values Y ' k , vector Y') are fed from the equalizer device 22 via the line bundle 27 to the evaluation device (not shown).
- the evaluation device (not shown).
- bit sequences determined are compared with reference / synchronization data bit sequences stored in a (not shown) storage device of the transceiver 14.
- the respectively received bit sequences can be assigned to a synchronization frame la or a data frame la, 2a, 3a (cf. FIG. 5).
- a synchronization frame la or a data frame la, 2a, 3a (cf. FIG. 5).
- the fact that during the synchronization frame la the above.
- Synchronization data bit sequences are transmitted, so a temporal coordination of the DSL data transmission between of the transmitting and the respectively receiving transceiver 14, 15 can be reached.
- the M (complex) symbol values Y k assigned to the M cosine carrier vibrations 3, 4, 5 are fed to an equalizer coefficient estimating means 25 via a line bundle 21 consisting of several different lines.
- the reference / synchronization data bit sequences transmitted during a synchronization frame 1 a are known in the transmitting / receiving device 14, and thus also the (complex) symbol values S k assigned to them in a phase star corresponding to the phase star shown in FIG. 1 ,
- the (complex) symbol values S k are read from the above-mentioned memory device (not shown here) of the transmitting / receiving device 14 and, according to FIG. 6, are supplied to the equalizer coefficient estimating means 25 via a line bundle 23 consisting of several different lines.
- the equalizer coefficient estimation means 25 - for each of the M channels or M frequency bands 16a, 16b, 16c, 16d, 16e, is separate -
- the expected value of the quotient S / Y k is determined, for example by averaging (for example using 10, 100 or 1000 consecutive, corresponding symbol values Y k or S k . These can be assigned, for example, to one and the same synchronization frame la, or, for example, also to several successive synchronization frames).
- the equalizer coefficient estimating means 25 determines the inverses H _1 k of the transfer function H k of the kth of the total M carriers:
- H _1 k E ⁇ S k / Y k ⁇ (formula (3))
- crosstalk interference can occur, which is caused by neighboring twisted-pair lines - particularly when DSL data transmission is currently being carried out via one (or more) neighboring twisted-pair line.
- the corresponding interferences are generally not correlated with the useful signal, so that the respective interfering signals are averaged out approximately when the above-mentioned formation of expected values or mean values (when considering a sufficiently large number of symbols Y k or S k ).
- the equalizer coefficient estimation means 25 is informed of the settings or filter coefficients last used in the equalizer device 22, in particular the above-mentioned FEQ k values (vector FEQ) (see formula (1)) ,
- FEQ k , N The most recently used FEQ k values (ie the M values of the vector FEQ) are hereinafter referred to as “FEQ k , N ” (and together form the vector FEQ H ), and the updated ones FEQ k values with "FEQ k , N + ⁇ " (these together form the vector FEQ N + ⁇ ).
- FEQ k , N + 1 ⁇ E ⁇ S k / Y k ⁇ + (1 - ⁇ ) FEQ k , N (formula (4))
- the functions of the equalizer coefficient estimating means 25, the Fourier transform device 19, the equalizer device 22, etc. explained above can be e.g. be fulfilled by several microprocessors communicating with each other in a suitable manner, or e.g. also from the same microprocessor.
- the equalizer device 22 can be set relatively quickly and with relatively high accuracy.
- the good signal equalization leads to a reduced bit error rate compared to the prior art.
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10160733 | 2001-12-11 | ||
DE10160733A DE10160733A1 (en) | 2001-12-11 | 2001-12-11 | Method for the continuous estimation of the equalization coefficients for wired transmission systems |
PCT/DE2002/004518 WO2003055117A2 (en) | 2001-12-11 | 2002-12-09 | Method for the continuous estimation of the equalizer coefficients for wire-bound transmission systems |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1593243A2 true EP1593243A2 (en) | 2005-11-09 |
Family
ID=7708750
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP02791618A Withdrawn EP1593243A2 (en) | 2001-12-11 | 2002-12-09 | Method for the continuous estimation of the equalizer coefficients for wire-bound transmission systems |
Country Status (5)
Country | Link |
---|---|
US (1) | US20050063499A1 (en) |
EP (1) | EP1593243A2 (en) |
CN (1) | CN1636348A (en) |
DE (1) | DE10160733A1 (en) |
WO (1) | WO2003055117A2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5500679B2 (en) * | 2010-03-19 | 2014-05-21 | シリコンライブラリ株式会社 | Radio transmission system and radio transmitter, radio receiver, radio transmission method, radio reception method, and radio communication method used therefor |
KR20140068563A (en) * | 2012-11-28 | 2014-06-09 | 한국전자통신연구원 | Apparatus and method for receiving satellite broadcasting |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5297169A (en) * | 1991-06-28 | 1994-03-22 | Telefonaktiebolaget L M Ericsson | Equalizer training in a radiotelephone system |
JP3145003B2 (en) * | 1995-03-23 | 2001-03-12 | 株式会社東芝 | Orthogonal frequency division multiplexing transmission system and transmitter and receiver thereof |
US6185251B1 (en) * | 1998-03-27 | 2001-02-06 | Telefonaktiebolaget Lm Ericsson | Equalizer for use in multi-carrier modulation systems |
JP3191767B2 (en) * | 1998-04-10 | 2001-07-23 | 三菱電機株式会社 | Digital communication device |
US7023938B1 (en) * | 1999-04-08 | 2006-04-04 | Nec Usa, Inc. | Receiver for discrete multitone modulated signals having window function |
US6252902B1 (en) * | 1999-09-13 | 2001-06-26 | Virata Corporation | xDSL modem having DMT symbol boundary detection |
US6856648B1 (en) * | 2000-07-17 | 2005-02-15 | Telefonaktiebolaget Lm Ericsson | Method and apparatus for equalizer updating and sampling rate control |
US6952445B2 (en) * | 2001-08-14 | 2005-10-04 | Murphy Charles D | Symbol constellations having second-order statistics with cyclostationary phase |
-
2001
- 2001-12-11 DE DE10160733A patent/DE10160733A1/en not_active Withdrawn
-
2002
- 2002-12-09 WO PCT/DE2002/004518 patent/WO2003055117A2/en active Application Filing
- 2002-12-09 CN CNA028280245A patent/CN1636348A/en active Pending
- 2002-12-09 US US10/498,080 patent/US20050063499A1/en not_active Abandoned
- 2002-12-09 EP EP02791618A patent/EP1593243A2/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO03055117A2 * |
Also Published As
Publication number | Publication date |
---|---|
WO2003055117A2 (en) | 2003-07-03 |
CN1636348A (en) | 2005-07-06 |
US20050063499A1 (en) | 2005-03-24 |
WO2003055117A3 (en) | 2005-09-01 |
DE10160733A1 (en) | 2003-08-28 |
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