JP2012114712A - Communication device and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device and a communication system which require reduced work for installation, capable of responding changes of transmission characteristics after the installation.SOLUTION: In a communication device and a communication system, when starting to send a transmission block, a sending side communication device sends a training sequence for waveform equalization between an identification sequence and the above sent data sequence, over a wired transmission line. A receiving side communication device identifies a communication device of the other party with regard to the received transmission block, calculates a tap factor for digital waveform equalization using the received training sequence when the communication device of the other party sends the transmission block, and performs digital waveform equalization and so on using the calculated tap factor on the received transmission block.

Description

  The present invention relates to a communication apparatus and a communication system that perform wired communication between substrates, between apparatuses, between devices, and the like.

When communication devices communicate with each other via a wired transmission path, such as between boards, between devices, between devices, etc., as the communication speed increases, normal communication occurs due to waveform distortion caused by transmission path characteristics, etc. There is a problem that it is becoming difficult to do.
For example, when a plurality of communication devices are interconnected via a transmission line, in addition to the original signal being communicated, the communication device on the receiving side has a connection part between the transmission lines or a transmission line with another communication device. The signal reflected by the connecting portion of the terminal is also received.

This reflected signal causes different delays due to differences in communication paths between communication devices, that is, differences in the arrangement and connection distance of communication devices during communication. When digital data is transmitted at a high speed, for example, a reflected signal with a delay of several bits is received.
Waveform equalization that compensates for waveform distortion is used as a countermeasure when normal communication cannot be performed due to such signal waveform distortion. (See Patent Document 1.)

In the conventional waveform equalization method, first, equalization characteristics are adjusted in advance for each combination of communication devices when a wired network is constructed, and stored in each communication device.
At the time of communication, the communication device on the receiving side identifies the communication device on the transmission side (that is, the partner communication device) based on the identification signal arranged at the head of the block of transmission data to be received.
Then, based on the stored equalization characteristic information, an equalization characteristic corresponding to communication with the identified transmission-side communication device (destination communication device) is set in the waveform equalizer, and the received signal Waveform equalization is performed.

  In this way, for each communication partner, by pre-adjusting and storing the equalization characteristics necessary for waveform equalization at the time of installation, the processing burden of equalization characteristic calculation at the time of communication is reduced, and the waveform etc. To improve communication quality.

JP 2003-101444 A

  However, in Patent Document 1, for example, (1) when the installation position of the communication device changes, (2) when there is clock fluctuation due to clock deviation or aging of the communication device, (3) between the communication device and the transmission path When the required equalization characteristic changes from the pre-adjusted equalization characteristic, such as when the impedance changes between the two, the waveform equalization is performed by setting the non-optimal equalization characteristic. There is a problem of distortion.

For example, in a communication system (see FIG. 1) in which four communication devices are connected to a wired transmission path, when the number of communication apparatuses is changed from four to three (see FIG. 2), or as a transmission path. If the length of the cable is changed, the previously adjusted equalization characteristic cannot be used, and the equalization characteristic needs to be adjusted again.
Therefore, in a communication system in which the transmission characteristics change, there is a problem that the effort for adjusting the equalization characteristics is large.

  The present invention has been made to solve the above-described problems, and provides a communication device and a communication system that can reduce the setting effort during installation and can cope with changes in transmission characteristics after installation. Objective.

  A communication device according to the present invention includes a transmitter that transmits a transmission block in which a data sequence is arranged after an identification sequence for identifying a communication device to a wired transmission path, and transmits the transmission block to a predetermined counterpart communication device. When starting, a training sequence for waveform equalization is transmitted between the identification sequence of the transmission block to be transmitted first and the transmission data sequence.

  Further, another communication device according to the present invention is arranged such that a data sequence is arranged after an identification sequence for identifying a communication device, and the identification sequence and the data sequence are transmitted when transmitted from a predetermined counterpart communication device for the first time. A receiver that receives a transmission block in which a training sequence for waveform equalization is arranged from a wired transmission path is provided, and the receiver performs identification of a partner communication device related to the received transmission block based on the identification sequence. Monitoring whether or not transmission is started from a predetermined partner communication device, and when transmission is started, the tap coefficient for digital waveform equalization is calculated using the received training sequence, and the calculation result is It is used to perform digital waveform equalization.

  Since the communication apparatus of the present invention is configured to arrange a training sequence in a transmission block and transmit or receive the transmission block in a specific case, the adjustment time when installing the communication apparatus or constructing the communication system is reduced. Since the equalization characteristic is changed using a training sequence during communication, the communication quality can be improved with respect to the change in the transmission characteristic after installation.

It is a schematic diagram which shows one example of the communication system in Embodiment 1 of this invention. It is a schematic diagram which shows one example of a communication system when the connection conditions of the communication apparatus in Embodiment 1 of this invention change. It is a schematic diagram which shows the principal part of the internal structure of the communication apparatus in Embodiment 1 of this invention. It is a schematic diagram which shows the principal part of the internal structure of the receiver of a communication apparatus in Embodiment 1 of this invention. It is a figure which shows the format of the transmission block transmitted at the time of the communication start in Embodiment 1 of this invention. It is a figure which shows the 1st modification of the format of the transmission block transmitted at the time of the communication start in Embodiment 1 of this invention. It is a figure which shows the 2nd modification of the format of the transmission block transmitted at the time of the communication start in Embodiment 1 of this invention. It is a figure which shows the transmission block transmitted during communication in Embodiment 1 of this invention. It is a figure which shows the transmission block transmitted between the same communication apparatuses in communication in Embodiment 1 of this invention. It is a figure which shows the transmission block in the case of switching to communication with a different communication apparatus in Embodiment 1 of this invention. It is a figure which shows the 1st modification of the transmission block in the case of switching to communication with a different communication apparatus in Embodiment 1 of this invention. It is a figure which shows the 2nd modification of the transmission block in the case of switching to communication with a different communication apparatus in Embodiment 1 of this invention. It is a figure which shows the transmission block transmitted / received during communication with the same communication apparatus in Embodiment 1 of this invention. It is a figure which shows the 1st modification of the transmission block transmitted / received during communication with the same communication apparatus in Embodiment 1 of this invention. It is a figure which shows the 2nd modification of the transmission block transmitted / received during communication with the same communication apparatus in Embodiment 1 of this invention. It is a schematic diagram which shows the principal part of the internal structure of the communication apparatus in Embodiment 2 of this invention. It is a schematic diagram which shows the relationship between the transmission signal and sampling timing in Embodiment 2 of this invention.

Embodiment 1.

Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS.
In the following description and drawings in each embodiment, the same or similar components are denoted by the same or similar reference numerals. In addition, a part of the description of the detailed configuration and the prior art unnecessary for the description of the gist of the present invention is omitted.

  Each figure is for explaining the configuration, structure, function, and operation in an easy-to-understand manner. The implementation of the communication method, apparatus, or communication system of the present invention depends on the specific configuration and name described in the figure. do not do. Moreover, the arrangement relationship and the number of each part are not limited to the structure and division | segmentation range as described in a figure.

First, the configuration of the communication system will be described.
1 and 2 are conceptual diagrams showing communication systems with different installation states in Embodiment 1 of the present invention.

In the figure, 100 is a wired transmission line, and 101 to 104 are communication devices.
Here, the arrows in the figure indicate that each of the communication apparatuses 101 to 104 performs both transmission and reception with respect to the wired transmission path 100. That is, in the present embodiment, a case where each of the communication apparatuses 101 to 104 is a communication apparatus having a transmission / reception function will be described as an example. However, the communication apparatus may have either one of transmission or reception.

The communication apparatuses 101 to 104 are connected to each other via a wired transmission path 100.
Here, as a signal transmission method in the wired transmission line 100, various transmission methods such as single signal transmission and differential signal transmission are possible, and various structures such as a coaxial line structure, a strip line structure, and a flat cable structure are possible. Is possible.
In addition, as the connection form between the wired transmission path 100 and the communication devices 101 to 104, various forms such as a bus connection, a star connection, and a tree connection are possible.

  The communication devices 101 to 104 include, for example, (1) a function that executes various applications such as a personal computer, and (2) simply transfers information input from another processing device (not shown) to the partner communication device. Various device forms are possible, such as what to do.

  As a communication method between communication apparatuses, various methods such as one-way communication, half-duplex communication, full-duplex communication, one-to-one communication, and one-to-many communication can be applied.

FIG. 3 shows a main part of the internal configuration of the communication apparatuses 101 to 104 connected to the wired transmission path 100.
Reference numeral 301 denotes a three-state buffer (also referred to as tri-state buffer), 302 denotes a transmitter, and 303 denotes a receiver.

  The three-state buffer 301 performs signal input / output control, and switches between three states: a state in which a signal is transmitted from the transmitter 302 (transmission mode), a state in which a signal is received by the receiver 303 (reception mode), and a high impedance state. Play a role.

The communication devices 101 to 104 set the state of the three-state buffer to the transmission mode or the reception mode at the start of communication or prior to the communication, so that transmission or reception is possible.
Instead of using the three-state buffer 301, other switching means such as providing a similar control function for the transmitter 302 and the receiver 302 itself may be used.

The transmitter 302 transmits, as a signal, a transmission block in which various series, which will be described later, are arranged, to another communication device (hereinafter, a partner communication device) that is a communication partner. Details of various sequences and transmission blocks will be described later.
In addition, when the term series is used in the following description, in addition to the case of indicating various information transmitted / received by a signal, a bit string, a numerical string, etc., a signal or signal portion corresponding to the various information, a bit string, a numerical string, etc. May show. In addition, when the term “signal” is used, it may indicate a signal waveform, sampled signal data, or the like in addition to the case where the signal itself is transmitted and received.

  The receiver 303 receives the signal transmitted from the transmitter 302 of the counterpart communication device from the wired transmission path 100, identifies the counterpart communication device, and performs waveform equalization on the received signal.

FIG. 4 shows a main part of the internal configuration of the receiver 303.
401 is an identification circuit, 402 is a delay circuit, 403 is a tap coefficient calculation circuit, and 404 is an equalization circuit.

  The identification circuit 401 receives the signal received from the wired transmission path 100 by the receiver 303 and identifies the counterpart communication device related to the transmission block in the signal. Further, the identification circuit 401 outputs the identification result and tap coefficient calculation control information to the tap coefficient calculation circuit 403 when communication with the counterpart communication device is started.

  The tap coefficient calculation control information includes (1) an instruction to start tap coefficient calculation, (2) a result of detection of a transmission block transmitted first from a predetermined counterpart communication device, and the like.

The delay circuit 402 receives the signal received by the receiver 303 from the wired transmission line 100 and outputs the delayed signal to the tap coefficient calculation circuit 403 and the equalization circuit 404.
The delay circuit 402 delays the signal at least until the identification circuit 401 completes identification of the communication device.

A tap coefficient calculation circuit 403 receives the identification result from the identification circuit 401 and tap coefficient calculation control information, and calculates a tap coefficient for digital waveform equalization based on the signal received from the wired transmission line 100. Further, the tap coefficient calculation circuit 403 outputs the calculated tap coefficient to the equalization circuit 404.
Examples of the algorithm for calculating the tap coefficient include an LMS algorithm, an NLMS algorithm, and an RLS algorithm. Moreover, it is also possible to calculate by the SMI algorithm, its approximation process, or the combined process with the previous algorithm.
The identification sequence may also be used for calculating the tap coefficient.

The equivalent circuit 404 receives the calculated tap coefficient information from the tap coefficient calculation circuit 403, performs a digital waveform equalization process on the delay signal output from the delay circuit 402, and outputs the result.
Examples of the technique of the equalization circuit 404 include linear equalization, decision feedback equalization, maximum likelihood sequence estimation, turbo equalization, and the like. However, the tap coefficient calculation algorithm of the tap coefficient calculation circuit and the equalization method of the equalization circuit 404 may use other than those listed here, and do not limit the present invention.

  The transmission / reception operation of the transmission block in communication between specific communication apparatuses will be described below.

  In this embodiment, in order to explain the invention in an easy-to-understand manner, a case of one-to-one communication in which a transmission block is transmitted from the communication apparatus 101 and received by the communication apparatus 104 will be described as an example.

First, the case where communication is started between communication devices will be described.
The communication apparatus 101 that is the communication apparatus on the transmission side sets the three-state buffer 301 to the transmission mode, and then transmits the transmission block to the wired transmission path 100.

FIG. 5 shows an example of the format of a transmission block to be transmitted.
In the figure, transmission blocks are transmitted and received sequentially from the left side.
In the transmission block, an identification sequence 501, a training sequence 502, and a data sequence 504 are arranged and configured in this order. In other words, the training sequence 502 is arranged between the identification sequence 501 and the data sequence 504.

The identification sequence 501 is used to identify each communication device. In the identification series 501, the device identification number assigned when the communication device is manufactured, when the communication device is installed in the communication system, or prior to communication is used as it is, or other information corresponding to the identification number is used. May be used.
The identification sequence 501 in the transmission block provides information on the communication device that transmits the transmission block to the counterpart communication device that is the receiving side.

Specifically, for example, the identification sequence 501 is assigned to each communication device as an identification sequence from among a plurality of sequences or combinations of codes having a small correlation between sequences, thereby increasing the identification accuracy of the transmitting device. Can do.
Furthermore, in order to suppress the influence of the reflected signal, the influence of the reflected signal can be suppressed by using a sequence having a small correlation when the reception time is shifted. Examples of such sequences include orthogonal codes, but are not limited to orthogonal codes.

  The training sequence 502 is used by the tap coefficient calculation circuit 403 of the communication device on the receiving side, here the communication device 104, to calculate tap coefficients for digital equalization processing.

  Although the identification sequence and the training sequence in the transmission block are handled as different ones, for example, a common sequence may be used, such as using a repetition of the identification sequence as a training sequence. In this case, identification and tap coefficient calculation can be performed efficiently by using both the identification sequence and the training sequence.

  The data series 504 is used for transmitting and receiving information such as user data, application data, and higher-level protocol data and a bit string that are actually transmitted and received between communication apparatuses.

6 and 7 show a modification of the format shown in FIG.
6 and 7, an identification sequence is further arranged separately between the training sequence and the data sequence, and a plurality of identification sequences are used in one transmission block.
Further, in FIG. 7, different identification sequences are assigned to a plurality of identification sequences. As a result, when the first identification sequence 601 and the training sequence 602 cannot be received and only the second identification sequence 603 is received, the receiver 303 determines whether to receive the training sequence or the data sequence next. It becomes possible.

On the other hand, the communication device 104 which is a communication device on the receiving side sets the three-state buffer 301 to the reception mode.
The identification circuit 501 of the receiver 303 calculates the correlation between the received identification sequence and the identification sequence corresponding to the partner communication device or the partner communication device candidate, and the calculation result is maximized, that is, the correlation is The maximum identification sequence is obtained, and it is determined that the received transmission block is transmitted from the communication apparatus to which the sequence is assigned.

  The identification circuit 401 monitors whether the received transmission block is the first transmission block after the start of communication with the communication apparatus 101, and if it is determined from the identification result that it is the first transmission block, the tap coefficient calculation circuit Tap coefficient calculation control information is output to 403 so that the tap coefficient is calculated.

  The tap coefficient calculation circuit 403 receives the tap coefficient calculation control information, calculates the tap coefficient based on the received training sequence, initializes or updates the tap coefficient, and equalizes the calculated tap coefficient information. The data is output to 404.

  The equalization circuit 404 changes the equalization characteristic based on the new tap coefficient.

Here, as a method of monitoring whether the received transmission block is the first transmission block after the start of communication, (1) a method monitored by the identification circuit 401, (2) training in an identification sequence as shown in FIG. Various methods such as a method of monitoring by including information for identifying presence / absence of a series and detecting the presence / absence in the identification circuit 401, (3) a method of combining the above (1) and (2) are possible.
In the case of (2) above, it is not monitored whether the received transmission block is the first transmission block after the start of communication, but only the presence / absence of a training sequence is monitored, and tap coefficient calculation and waveform are performed according to the result. You may make it equalize.

Next, a case where data is continuously transmitted / received between the communication device 101 and the communication device 104 after the start of communication will be described.
In this case, continuous data can be collectively transmitted and received as a data sequence in one transmission block, or can be continuously transmitted and received in a transmission block in which no training sequence is arranged as shown in FIG.

  In the case of FIG. 8, (1) a method in which continuous data is divided and arranged into a plurality of data series and an identification series is arranged before each data series, and (2) an identification series is additionally added in one transmission block. It can be seen that any of the arrangement methods results in a similar format.

  In the case of FIG. 8, communication can be performed while constantly confirming the partner communication device during communication.

Next, a case will be described in which transmission / reception of a transmission block between the same communication apparatuses is interrupted for a short time, and then transmission is resumed.
In this case, since it can be considered that the transmission characteristics do not change greatly, as shown in FIG. 9, it is also possible to transmit without arranging the training sequence in the transmission block after restart. In this case, the communication device 104 on the receiving side operates the equalization circuit 404 using the tap coefficient used before the interruption.
Note that the tap coefficient may be calculated by using the identification sequence, and the tap coefficient may be updated in the tap coefficient calculation circuit 403 or the equalization circuit 404 so as to compensate for a variation in time when there is no communication.

Next, as another case of starting communication between predetermined communication devices, when the communication device on the transmission side is switched from the communication device 104 to another communication device without changing the communication device 104 on the reception side, that is, the transmission block is changed. A case where the transmission side communication apparatus is switched will be described.
FIG. 10 shows a state of transmission of the transmission block when switching to communication with a different communication device.
In the figure, a transmission block in which an identification sequence A 901 and a data sequence 902 are arranged is transmitted from the counterpart communication device 101 before switching, and then transmission in which a training sequence 1002 is arranged from the counterpart communication device after switching. You can see that the block was sent first.

  When the identification circuit 401 of the communication device 104 on the receiving side detects that the received transmission block is the first transmission block from the communication device after switching, the tap coefficient information is updated, and after switching Waveform equalization is performed with respect to the transmission block received from the counterpart communication device.

11 and 12 show a modification of FIG.
Since the transmission block that is first transmitted from the partner communication device after switching is the same as the modification of FIG. 5 shown in FIGS. 6 and 7, detailed description thereof is omitted.

  Similar to the case shown in FIGS. 5 to 7, the receiving communication apparatus 104 can use the identification sequence in addition to the training sequence to calculate the tap coefficient.

  Next, in the present embodiment, a case will be described in which transmission from the same counterpart communication apparatus is resumed after transmission of a transmission block is interrupted for a long time during communication.

  As shown in FIG. 13, when the interrupted period X is equal to or longer than a predetermined time (preset time), a transmission block in which the training sequence 1302 is arranged is transmitted even for communication between the same communication apparatuses. To do. The period X includes (1) prescribed in the communication system, (2) information exchange between the communication devices separately before communication or transmission / reception, (3) notification from the transmission side communication device to the reception side communication device, and the like. A method is possible.

  14 and 15 show a modification of FIG.

  The transmission block that is first transmitted after the transmission is resumed is the same as the modification shown in FIG. 6 and FIG. 7 or FIG. 11 and FIG.

As described above, the communication device according to the present embodiment, when transmission of a transmission block is started, or when transmission / reception is interrupted for a predetermined time during communication between the same communication devices and then resumed, The arranged transmission block is transmitted, and the tap coefficient calculation is updated or initialized by the transmission block in which the training sequence is arranged to perform digital waveform equalization processing.
As a result, it is possible to reduce the trouble of adjustment at the time of installing the communication device, and since the training sequence is transmitted and received in a specific case as described above, the overhead during communication is not greatly increased. Good communication can be realized while suppressing an increase in system redundancy.

  In this embodiment, the case where the receiver 303 includes the delay circuit 402 has been described. However, even if the delay circuit 402 is not provided, the tap coefficient is calculated by the training sequence after receiving the identification sequence. Therefore, a configuration without a delay circuit may be used.

  In this embodiment, the identification sequence is used to identify the transmission-side communication device in the reception-side communication device. However, information for identifying the reception-side communication device is added to the identification sequence. May be. As a result, the communication device on the receiving side can be prevented from processing a transmission block that does not require reception, so that energy consumption can be reduced.

In this embodiment, the coefficient is not changed after the tap coefficient calculation circuit 404 sets the tap coefficient. However, after the tap coefficient calculation circuit 404 sets the tap coefficient in the equalization circuit, the tap coefficient is finely adjusted. It may be performed continuously.
Further, the tap coefficient calculation circuit 403 may calculate the tap coefficient for equalization using the identification series 601 in addition to the training series 602 and set it in the equalization circuit 404.

Embodiment 2.

The second embodiment of the present invention will be described below with reference to FIGS.
In the following description, differences from the first embodiment will be mainly described.

  FIG. 16 is a schematic diagram showing the main part of the internal configuration of the receiver of the communication apparatus according to Embodiment 2 of the present invention.

  In this embodiment, the identification circuit 1601 and the delay circuit 1602 in Embodiment 1 are connected.

  The identification circuit 1601 samples the received signal, identifies the communication device that transmitted the transmission block based on the sampling result, and outputs information for instructing the delay circuit 1602 to change the delay time. .

  The delay circuit 1602 receives an instruction from the identification circuit 1601 and changes the delay time.

FIG. 17 is a schematic diagram showing the relationship between the transmitted signal and the sampling timing in the identification circuit 401 in the second embodiment of the present invention.
In the figure, (A), (B), and (C) indicate sampling timings.

The identification circuit 1601 samples the signal of the received transmission block at a sampling timing shorter than the time of 1 bit, calculates the correlation between the sampling result at each timing and the identification sequence or the identification sequence candidate. Select a large timing as the optimal timing.
The identification circuit 1601 instructs the delay circuit 1602 to change the delay time so that the received signal is input to the tap coefficient calculation circuit 403 and the equalization circuit 404 with reference to the selected timing.

  As described above, in the communication device and the communication system according to the present embodiment, equalization can be performed by adjusting the timing of a signal for performing waveform equalization, and therefore communication is performed between communication devices operating asynchronously. Even in this case, good communication can be performed.

  In each of the above embodiments, the communication operation between communication devices and the transmission (reception) operation of the transmission block are described separately. (1) Information for separately setting a communication partner at the start of communication It is configured to perform exchange, and thereafter, configured to perform transmission / reception of the transmission block described in each of the above embodiments. (2) Communication start between communication devices by transmission start of the transmission block described in each of the above embodiments An apparatus or the like may be configured so as to be considered.

  At that time, in addition to the transmission block for data transmission described in each of the above embodiments, a transmission block for communication control is defined, and a series or transmission block similar to that described in each of the above embodiments is defined. May be.

  Further, in each of the above embodiments, a specific mounting method is not described, but (1) hardware is configured and operated, (2) software is operated by a program and a processing device, and (3) hardware Various implementations such as mixing software and software are possible.

  In each of the above embodiments, the training sequence is arranged only for the transmission block that is transmitted first at the start of communication, after the transmission is interrupted for a predetermined period or more, and at the time of switching the partner communication device. Training sequences may be arranged in a predetermined number of blocks. The predetermined number of values may be exchanged between communication devices prior to communication, or may be defined in advance when designing the communication system.

  Further, in each of the above embodiments, when a plurality of identification sequences are arranged and transmitted in a transmission block, different identification sequences indicating the same communication device are arranged, but the order is changed from that shown in the figure. The order is not limited.

  Also, the format of a plurality of transmission blocks is shown for each operation at the start of communication, after interruption of transmission for a predetermined period or more, and at the time of switching the partner communication device. (1) The same format at each operation Various usage methods such as using (2) using different formats can be applied.

  In each of the above embodiments, each series is arranged adjacent to each other in the transmission block. However, a fixed pattern defined in advance, for example, one bit of a fixed value is arranged before or between series. Also good.

  Further, each of the above embodiments is an exemplification, and the arrangement and position of each part within a range that does not depart from the technical idea of the present invention by a person having ordinary knowledge in the technical field, including combinations of the above embodiments. Various modifications such as relationships and operating conditions are possible.

100 Transmission path 101, 102, 103, 104 Communication device 301 Three-state buffer 302 Transmitter 303 Receiver 401, 1601 Identification circuit 402, 1602 Delay circuit 403 Tap coefficient calculation circuit 404 Equalization circuit 1701 Signal waveform 1702-1704 Sampling timing

Claims (11)

A transmitter for transmitting a transmission block in which a data sequence is arranged after a first identification sequence for identifying a communication device to a wired transmission path;
The transmitter is
When starting transmission of the transmission block to a predetermined counterpart communication device,
A communication apparatus which transmits a training sequence for waveform equalization between the identification sequence of the transmission block to be transmitted first and the transmission data sequence. The transmitter is
When the transmission of the transmission block to the predetermined counterpart communication device is interrupted for a predetermined time and then restarted,
The communication apparatus according to claim 1, wherein a training sequence for waveform equalization is transmitted between the identification sequence of the transmission block to be transmitted first and the transmission data sequence. The transmitter is
The communication apparatus according to claim 1, wherein a second identification series for identifying the communication apparatus is transmitted between the training series and the data series.   The communication apparatus according to claim 1, wherein the identification sequence includes identification information assigned to each of the communication apparatuses that perform the transmission.   The communication apparatus according to claim 1, wherein the identification sequence further includes information indicating presence / absence of the training sequence in the transmission block. A data sequence is arranged after an identification sequence for identifying a communication device, and a training sequence for waveform equalization is provided between the identification sequence and the data sequence when transmitted first from a predetermined counterpart communication device. The transmission block to be arranged
It has a receiver that receives from a wired transmission line,
The receiver is
The identification of the counterpart communication device related to the received transmission block is performed based on the identification series, and monitoring whether transmission is started from the predetermined counterpart communication device,
When transmission from the predetermined counterpart communication device is started,
A communication apparatus, wherein a tap coefficient for digital waveform equalization is calculated using the received training sequence, and digital waveform equalization is performed on the received transmission block using a result of the calculation. A data sequence is arranged after an identification sequence for identifying a communication device, and a training sequence for waveform equalization is provided between the identification sequence and the data sequence when transmitted first from a predetermined counterpart communication device. The transmission block to be arranged
It has a receiver that receives from a wired transmission line,
The receiver is
While performing identification of the counterpart communication device related to the received transmission block based on the identification series,
Monitoring the presence of the training sequence of the received transmission block;
If there is the training series,
A communication apparatus, wherein a tap coefficient for digital waveform equalization is calculated using the received training sequence, and digital waveform equalization is performed on the received transmission block using a result of the calculation. The receiver is
When transmission from the predetermined partner communication device is interrupted for a predetermined time and then restarted,
The tap coefficient for digital waveform equalization is calculated using the received training sequence of the transmission block, and the digital waveform equalization is further performed on the received transmission block using the calculation result. The communication device according to claim 6 or 7. The receiver is
A sampling timing with the highest correlation between the identification sequence of the received transmission block sampled at intervals shorter than the time length of 1 bit and the identification sequence candidate is selected, and the correlation is the highest 9. The communication apparatus according to claim 6, wherein the tap coefficient is calculated and the digital waveform is equalized at a sampling timing. A transmission block in which a data sequence is arranged after an identification sequence for identifying a communication device includes a transmitter that transmits the transmission block to a wired transmission path, and a receiver that receives the transmission block from the wired transmission path,
The transmitter is
When starting transmission of the transmission block to a predetermined counterpart communication device, a training sequence for waveform equalization is transmitted between the identification sequence of the transmission block to be transmitted first and the transmission data sequence. ,
The receiver is
The identification of the counterpart communication device related to the received transmission block is performed based on the identification series, and monitoring whether transmission is started from the predetermined counterpart communication device,
When transmission from the predetermined counterpart communication device is started,
A tapping coefficient for digital waveform equalization is calculated using a training sequence of the received transmission block, and digital waveform equalization is performed on the received transmission block using a result of the calculation. system. A transmission block in which a data sequence is arranged after an identification sequence for identifying a communication device includes a transmitter that transmits the transmission block to a wired transmission path, and a receiver that receives the transmission block from the wired transmission path,
The transmitter is
When starting transmission of the transmission block to a predetermined counterpart communication device, a training sequence for waveform equalization is transmitted between the identification sequence of the transmission block to be transmitted first and the transmission data sequence. ,
The receiver is
While performing identification of the counterpart communication device related to the received transmission block based on the identification series,
Monitoring the presence of the training sequence of the received transmission block;
If there is the training series,
A tapping coefficient for digital waveform equalization is calculated using a training sequence of the received transmission block, and digital waveform equalization is performed on the received transmission block using a result of the calculation. system

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