JP2001308819A - Communications equipment and method for eliminating interference in the communications equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide communications equipment, capable of eliminating mutual interference between a TCM-ISDN and an ADSL or between ADSLs, and its interference eliminating method. SOLUTION: All the mutual interference occurring between the TCM-ISDN and the ADSL, which use lines having the same characteristic and also use the same reference signal, and all the interferences occurring between the ADSLs are eliminated by delaying the TTR in a self-ATU-C as much as S1 and further adjusting the TTR to be transmitted to an ATU-R to be the opposite communication party, backward and forward as much as S2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
The present invention relates to a communication device that performs data communication by an MT (discrete multi tone) modulation / demodulation method.
(Time Compression Multiplexing)
Between ISDN and ADSL or ADSL and A
The present invention relates to a communication device for removing mutual interference between DSLs and a method for removing the interference.

[0002]

2. Description of the Related Art A conventional communication device will be described below. First, the operation of a transmission system in a conventional communication device that performs data communication using the DMT (Discrete Multi Tone) modulation / demodulation method will be briefly described. For example, when performing data communication by the DMT modulation / demodulation method using an existing transmission line such as a telephone line, the transmission system performs tone ordering processing, that is, S / N (signal-to-noise rati) of the transmission line.
o: A process of allocating transmission data of a number of bits that can be transmitted to each of a plurality of tones (multi-carriers) in a preset frequency band based on the signal-to-noise ratio (the transmission rate is determined by this process). Do). Specifically, for example, tone0 to tone of each frequency
X (X is an integer indicating the number of tones) is assigned transmission data of a bit number according to the S / N ratio.

[0003] A tone ordering process and an encoding process according to the S / N ratio are performed, so that 1
Transmission data is multiplexed for each frame. Further, the transmission system performs an inverse fast Fourier transform (IFFT) on the multiplexed transmission data, converts the parallel data after the inverse fast Fourier transform into serial data, and then performs D / D conversion.
The digital waveform is converted into an analog waveform through an A converter, and finally a low-pass filter is applied to transmit the transmission data over a telephone line.

Next, the operation of a receiving system in a conventional communication device for performing data communication according to the DMT modulation / demodulation method will be briefly described. Similarly to the above, when performing data communication by the DMT modulation / demodulation method using an existing transmission line such as a telephone line, the reception system applies a low-pass filter to the reception data (the transmission data described above), and then performs A / D conversion. An analog waveform is converted into a digital waveform through a D converter, and a time domain equalizer performs a time domain adaptive equalization process.

The data subjected to the time-domain adaptive equalization processing is converted from serial data to parallel data.
Performs a fast Fourier transform on the parallel data,
After that, the frequency domain equalizer performs a frequency domain adaptive equalization process.

[0006] The data subjected to the adaptive equalization processing in the frequency domain is converted into serial data by a composite processing (maximum likelihood composite method) and tone ordering processing, and thereafter, rate conversion processing and FEC (forward error) processing are performed.
correction: forward error correction), descrambling, C
Processing such as RC (cyclic redundancy check) is performed, and finally the transmission data is reproduced.

Using the DMT modulation and demodulation method as described above,
Wired digital communication systems for data communication include:
ADSL (Asymmetrical Digital Sub) that performs high-speed digital communication of several megabits / second using existing telephone lines
xDSL communication system such as a subscriber line communication system.
This method is standardized in ANSI T1.413 and the like. In this digital communication system, in particular, AD
The SL transmission line and the ISDN transmission line of the ISDN communication system of the half-duplex communication system are bundled by a set line in the middle and are adjacent to each other. It should be noted that the ISDN communication system referred to here is a system conventionally used in NTT, for example, a TCM-ISDN service, and this service is also commonly called a ping-pong system.

FIG. 9 shows a signal flow in a TCM-ISDN service conventionally provided by NTT. In this service, for example, FIG.
As shown in the figure, an OCU (Office Channel Unit: intra-office line terminating device), that is, an ISDN-DS
(Downstream) and DSU (Digital Service Un
it: digital line terminator), that is, the ISDN-DS is received on the receiving device side. Then, on the receiving device side, 7 UI (1 UI: 3.125) from the time of completion of reception.
μs), ISDN-US (Upstream) is transmitted, and the base station receives the ISDN-US.

More specifically, the DSU is an ISDN
In the service, for example, as shown in FIG.
There is a delay according to the distance to the CU. For example, OC
The distance between U and DSU is short (here, distance 0 is shown)
If there is no delay, the OCU transmits the ISDN-DS and the DSU receives the ISDN-DS at the same time.
Also, ISDN-US transmitted from DSU after 7 UI
Is also transmitted to the OCU without delay. On the other hand, if the distance between the OCU and the DSU is a long distance (here, a long-distance limit is indicated), when the OCU transmits the ISDN-DS, the DSU transmits the ISDN-DS after a predetermined delay time.
Receive the DN-DS. Similarly, the ISDN-US transmitted from the DSU after 7 UI is transmitted to the OCU after a predetermined delay time has elapsed. It should be noted that the illustrated T
TR (TCM-ISDN Timing Reference) is a signal serving as a reference for synchronization at the time of DS and US on a network. In TCM-ISDN, only the base station can know this timing. Also,
Here, one cycle of the TTR is, for example, 2.5 ms.

On the other hand, the ADSL transmission line is bundled with and adjacent to the above-mentioned TCM-ISDN transmission line of the half-duplex communication method by a collective line on the way. Therefore, ADSL and TC
If timing adjustment is not performed between the M-ISDNs, the TCM-ISDN signal becomes an interference signal, and the ADS
The communication characteristics in L will be degraded. That is,
As shown in FIG. 10, NEXT (Near End Cross Tal
k) Communication characteristics in ADSL deteriorate due to generation of noise and FEXT (Far End Cross Talk) noise.

Therefore, in the ADSL service, as shown in FIGS. 11 and 12, a boundary (shown by a dotted line) taking delay into account is provided, and a DCM is set for DS in TCM-ISDN.
S and US when TCM-ISDN is US. FIGS. 11 and 12 show the symbol format of a hyperframe in ADSL.
One hyperframe is composed of 345 symbols. Here, one hyperframe is set to 85 ms, and this value is a multiple of the TTR (2.5 ms) described above.
Although FIGS. 11 and 12 show an example of a hyperframe including a cyclic prefix, the same operation is performed in a hyperframe not including a cyclic prefix. However, in this case, 1
A hyperframe (345 symbols) is 80 ms.

The shaded portion in FIG.
T _R data symbols (when the receiving apparatus side of the FEXT period, means) and call, and other data NEXT _R
This is referred to as a data symbol (meaning when the receiving apparatus is in the NEXT period). The shaded portion in FIG. 12 is called a FEXT _C data symbol (meaning that the base station side is in the FEXT period), and the other data is NEXT.
_{This is referred to as a C} data symbol (which means when the base station is in the NEXT period).

[0013] More specifically, the ISDN-
At the time of DS transmission, FEXT-DS transmission is performed at ATU-C, and at the time of ISDN-US transmission by DSU, ATU-R
Performs FEXT-US transmission.

As a result, the conventional ADSL communication apparatus is not affected by the interference of DS and US in TCM-ISDN, and the communication characteristics are not degraded due to TCM-ISDN.

[0015]

SUMMARY OF THE INVENTION However,
In the conventional communication device, the influence of the ADSL on the TCM-ISDN and the influence of the ADSL interference are not considered.

First, the interference that ADSL gives to the TCM-ISDN will be specifically described. For example, as shown in FIG. 9, when the distance between the OCU and the DSU is “0”,
Since there is no delay, the transmission and reception timing of ISDN-DS,
And the transmission / reception timing of ISDN-US coincide with each other at a point and a point, respectively. However, OCU
ISDN if the distance between DSU and DSU is "long distance limit"
DS is received with a delay of 16 UI (50 μs: between FIG. 1), and ISDN-US also receives
Arriving late (between "-" in FIG. 1), a total delay of 32 UI occurs. At this time, I in the OCU
SDN-US reception will cross the boundary of the NEXT period.

As a result, A surrounded by a circle shown in FIG.
FEXT _R data symbols from the TU-C (eg,
(Symbol numbers 10, 81, 142, 213, 284)
Is the interference component to the OCM of TCM-ISDN (NE
XT noise), and the communication characteristics in the ISDN service deteriorate. That is, the reception of the OCU corresponds to the ATU-C
However, there is a problem that the FEXT-DS transmission may receive interference.

Next, interference between ADSLs will be specifically described. For example, in ADSL, ATU
-C is TT for ATU-R as shown in FIG.
R is being transmitted. Therefore, the TTR of ATU-R
Is a maximum of 20 UI (TCM-IS
Considering the margin for 16 UI maximum delay time of DN, it is 20 UI, but TCM-ISDN and ADS
L uses substantially the same transmission path, so the actual maximum delay time is 16 UI).
In this case, if the TTR of the ATU-R has a delay of 20 UI, the FTR from the ATU-R operating synchronously
EXT-US reception will have a delay of up to 40 UI.

At this time, in the other ATU-C and the own ATU-C that are synchronized with the hyperframe, for example, even if the symbol number 81 shown in FIG. 11 is used, as shown in FIG. Since FEXT-US transmission is performed up to the point, no interference occurs even when the FEXT-US transmission is delayed by a maximum of 40 UI. However, in another ATU-C that is not synchronized with the hyperframe, the FEXT-DS transmission of the symbol number 81 shown in FIG. 11 may cause interference with the FEXT-US reception at a marginal boundary such as the symbol number 39, for example. Become. That is, FEXT-DS of ATU-C
There is a problem that transmission becomes NEXT noise with respect to FEXT-US reception of another ATU-C.

The present invention has been made in view of the above, and has been made between TCM-ISDN and ADSL, or AD
An object of the present invention is to provide a communication device capable of removing interference between SL and ADSL and a method of removing the interference.

[0021]

Means for Solving the Problems To solve the above-mentioned problems,
In order to achieve the object, a communication device according to the present invention has a reference signal for synchronization with respect to a downstream and an upstream, and transmits the reference signal to a communication partner device, thereby enabling mutual communication. The data communication by ADSL is performed by establishing the synchronization of, and the reference signal in the own communication device is delayed by a first predetermined time.
Another communication system that uses a line having the same characteristics and performs communication using the same reference signal by adjusting the reference signal transmitted to the communication partner device back and forth by a second predetermined time. , And the ADSL, and all the mutual interference occurring between the ADSLs are eliminated.

According to the present invention, for example, the own communication device (ATU-C) can transmit the TTR (reference signal) in the own ATU-C.
Is shifted by S ₁ (first predetermined time), and the ATU-C F
EXT-DS is an ISDN (other communication system) IS
Do not start DN-US reception. Also, ATU
In -C, in the interior of the TTR which is delayed previously only S _1, AT
The TTR is transmitted to the ATU-R (communication partner device) with a variable delay S ₂ (second predetermined time) according to the distance from the U-R. That is, the AEXT-C FEXT-DS transmission is synchronized (hyperframe synchronization).
Not achieved in so as not to interference with FEXT-US reception of other ATU-C, to adjust the S _2. This allows mutual interference between ADSL and ISDN, and A
All interference between DSLs can be eliminated.

In the communication device according to the next invention,
Based on a relational expression between the communication device on the transmitting side and the communication device on the receiving side where interference is most likely to occur, an allowable range for the first predetermined time is calculated, and a value that maximizes the margin of the allowable range is set to the first value. It is characterized in that the predetermined time is fixed.

According to the present invention, the first predetermined time is calculated using the relational expression at the point where interference is most likely to occur under the condition of the maximum transmission path delay, that is, the point having the least margin in the relational expression. I do. As a result, other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated.

In the communication device according to the next invention,
From the relational expressions of all transmission-side communication devices and reception-side communication devices in which interference may occur, and the first predetermined time, a second expression corresponding to the range of the transmission path delay to be compensated is obtained. It is characterized in that an allowable range of a predetermined time is calculated, a value that always maximizes a margin is calculated in response to the fluctuation of the transmission path delay, and the calculated value is set as a second predetermined time.

According to the present invention, S ₁ uniquely calculated from (first predetermined time) and S ₂ (second predetermined time) one relational expressions corresponding respectively, in ADSL is calculated here only S ₁ and S ₂ were shifts the TTR (reference signal). As a result, ADSL and IS
All interference between DNs and between ADSLs can be eliminated.

In the communication device according to the next invention,
From the relational expressions of all transmission-side communication devices and reception-side communication devices in which interference may occur, and the first predetermined time, a second expression corresponding to the range of the transmission path delay to be compensated is obtained. An allowable range of the predetermined time is calculated, and the second predetermined time is fixed within the allowable range of the second predetermined time even if the transmission path delay fluctuates.

According to the present invention, S ₂ (second predetermined time) is fixed to a value satisfying the allowable range in advance. This allows ADSL interference to ISDN, and A
DSL interference can be eliminated,
Further, S ₂ can be fixed to a plurality of values, and it is not necessary to calculate S ₂ by calculating a relational expression. Therefore, the amount of calculation is reduced, and the processing is accelerated. In the communication, by the S ₂ to be relatively rare case (a value close to the maximum value and the minimum value of the allowable range) as an optional feature, can be fixed to S ₂ to one, further, the calculation amount is reduced In addition, speeding up of processing is further promoted.

In the communication device according to the next invention,
Before establishing communication between the devices in the ADSL, measurement of a transmission path delay between the devices and calculation of the first predetermined time and the second predetermined time are performed to establish communication without interference. It is characterized by.

According to the present invention, ATU-C and AT
Before the U-R establishes hyperframe synchronization, the ATU
-C calculates the transmission path delay. Thereby, S ₁ (first predetermined time) and S ₂ (second predetermined time) for delaying TTR (reference signal) can be easily obtained,
Communication can be established without interference.

In the communication apparatus according to the next invention, the transmission path delay is calculated based on a round trip time of a specific signal between the apparatuses.

According to the present invention, since the RTD (round-trip time of a specific signal) is measured, the calculation is very easy, and the processing time by the ATU-R is short. Also, for example, by performing communication at twice the frequency of the return path, since the frequency does not overlap between the uplink and the downlink, the ATU-
C can easily recognize the signal from the ATU-R.

In the interference elimination method according to the next invention, the reference signal in the own communication device is delayed by a first predetermined time, and the reference signal to be transmitted to the communication partner device is further delayed for a second predetermined time. , The mutual interference between the ADSL and another communication system using a line having the same characteristics and performing communication using the same reference signal, and ADSL. It is characterized in that all mutual interference occurring between them is eliminated.

According to the present invention, for example, the own communication device (ATU-C) can transmit the TTR (reference signal) in the own ATU-C.
Is shifted by S ₁ (first predetermined time), and the ATU-C F
EXT-DS is an ISDN (other communication system) IS
Do not start DN-US reception. Also, ATU
In -C, in the interior of the TTR which is delayed previously only S _1, AT
The TTR is transmitted to the ATU-R (communication partner device) with a variable delay S ₂ (second predetermined time) according to the distance from the U-R. That is, the AEXT-C FEXT-DS transmission is synchronized (hyperframe synchronization).
Not achieved in so as not to interference with FEXT-US reception of other ATU-C, to adjust the S _2. This allows mutual interference between ADSL and ISDN, and A
All interference between DSLs can be eliminated.

In the interference elimination method according to the next invention, the allowable range of the first predetermined time is calculated based on the relational expression between the transmitting-side communication device and the receiving-side communication device where interference is most likely to occur. The value that maximizes the margin of the allowable range is fixed as the first predetermined time.

According to the present invention, the first predetermined time is calculated using the relational expression of the point where interference is most likely to occur under the condition of the maximum transmission path delay, that is, the least margin in the relational expression. I do. As a result, other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated.

In the interference elimination method according to the next invention, the relational expression between all the communication apparatuses on the transmitting side and the communication apparatuses on the receiving side, which may cause interference, the first predetermined time and From the second, according to the range of the transmission path delay to be compensated
Is calculated, and a value that maximizes the margin is always calculated in response to the fluctuation of the transmission path delay, and the calculated value is set as a second predetermined time.

According to the present invention, S ₁ (first predetermined time) and S ₂ (second predetermined time) can be uniquely calculated from one corresponding relational expression. only S ₁ and S ₂ were shifts the TTR (reference signal). As a result, ADSL and IS
All interference between DNs and between ADSLs can be eliminated.

In the interference elimination method according to the next invention, the relational expression between all the communication devices on the transmitting side and the communication device on the receiving side that may cause interference, the first predetermined time, From the second, according to the range of the transmission path delay to be compensated
Is calculated within the allowable range of the second predetermined time even if the transmission path delay fluctuates.
Is fixed for a predetermined time.

According to the present invention, S ₂ (second predetermined time) is fixed to a value satisfying the allowable range in advance. This allows ADSL interference to ISDN, and A
DSL interference can be eliminated,
Further, S ₂ can be fixed to a plurality of values, and it is not necessary to calculate S ₂ by calculating a relational expression. Therefore, the amount of calculation is reduced, and the processing is accelerated. In the communication, by the S ₂ to be relatively rare case (a value close to the maximum value and the minimum value of the allowable range) as an optional feature, can be fixed to S ₂ to one, further, the calculation amount is reduced In addition, speeding up of processing is further promoted.

In the interference elimination method according to the next invention, before establishing communication between the devices in the ADSL, measurement of a transmission path delay between the devices, and the first predetermined time and the second predetermined time are performed. It is characterized in that time is calculated and communication is established without interference.

According to the present invention, ATU-C and AT
Before the U-R establishes hyperframe synchronization, the ATU
-C calculates the transmission path delay. Thereby, S ₁ (first predetermined time) and S ₂ (second predetermined time) for delaying TTR (reference signal) can be easily obtained,
Communication can be established without interference.

In the interference elimination method according to the next invention, the transmission line delay is calculated based on a round trip time of a specific signal between the devices.

According to the present invention, since the RTD (round trip time of a specific signal) is measured, the calculation is very easy, and the processing time by the ATU-R is short. Also, for example, by performing communication at twice the frequency of the return path, since the frequency does not overlap between the uplink and the downlink, the ATU-
C can easily recognize the signal from the ATU-R.

In the interference elimination method according to the next invention, the permissible range of the first predetermined time is calculated based on the relational expression between the communication device on the transmitting side and the communication device on the receiving side where interference is most likely to occur. Then, a value that maximizes the margin of the permissible range is fixed as a first predetermined time, and the fixed first predetermined time is substituted into all the relational expressions. Based on the relational expression between the communication device on the transmitting side and the communication device on the receiving side, the allowable range of the second predetermined time is calculated, and the value that maximizes the margin of the allowable range is fixed as the second predetermined time. It is characterized by doing.

According to the present invention, the first and second predetermined times are determined by the relational expression of the point where interference is most likely to occur, that is, the point having the smallest margin among the relational expressions, regardless of the condition of the transmission line delay. Calculated using As a result, other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated. Further, since the first and second predetermined times are fixed values, it is not necessary to change the value each time depending on conditions such as a transmission line delay, so that the calculation amount of each device can be reduced.

In the interference elimination method according to the next invention, the allowable range of the first predetermined time is calculated based on the relational expression between the communication device on the transmitting side and the communication device on the receiving side where interference is most likely to occur. Then, a value that maximizes the margin of the permissible range is fixed as a first predetermined time, and the fixed first predetermined time is substituted into all the relational expressions. Based on the relational expression between the communication device on the transmitting side and the communication device on the receiving side, the allowable range of the second predetermined time is calculated, and the value that maximizes the margin of the allowable range is fixed as the second predetermined time. It is characterized by doing.

According to the present invention, the first and second predetermined times are determined by the relational expression of the point where interference is most likely to occur, that is, the point having the least margin among the relational expressions, regardless of the condition of the transmission line delay. Calculated using As a result, other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated. Further, since the first and second predetermined times are fixed values, it is not necessary to change the value each time depending on conditions such as a transmission line delay, so that the calculation amount of each device can be reduced.

In the communication device according to the next invention,
In the relational expression, a delay caused by internal processing in the communication device on the transmission side and the reception side, and a predetermined condition for more strictly protecting the other communication system from interference, are newly added. The first predetermined time and the second predetermined time are calculated based on a relational expression reflecting the above.

According to the present invention, in the communication apparatus, for example, a loop timing margin, a system margin, a guard interval in ISDN, a TTR
The first predetermined time and the second predetermined time are calculated by adding a new condition such as a condition for prohibiting transmission and reception over a cycle. As a result, the first predetermined time and the second scheduled time with higher accuracy can be calculated, and accordingly, the interference between the devices can be more accurately removed.

In the interference elimination method according to the next invention, the relational expression satisfies the delay caused by internal processing in the communication device on the transmission side and the reception side, and more strictly protects the other communication system from interference. Predetermined conditions for
Are newly added, and the first predetermined time and the second predetermined time are calculated based on a relational expression reflecting those conditions.

According to the present invention, the first predetermined time and the second predetermined time are, for example, a new value such as a loop timing margin, a system margin, a guard interval in ISDN, a condition for prohibiting transmission / reception over the TTR cycle, and the like. It is calculated based on a relational expression to which a simple condition is added. Thereby, the first predetermined time with higher accuracy,
And the second scheduled time can be calculated, so that the interference between the devices can be more accurately removed.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a communication apparatus and an interference removing method according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited by the embodiment.

Embodiment 1 FIG. 1 is a diagram showing an outline of an interference removal method according to the present invention. Here, first, the basic operation of the communication device that executes the interference cancellation method of the present invention will be described with reference to the drawings. DMT (Discrete Multi Tone)
As a wired digital communication system for performing data communication using the modulation and demodulation system, an ADSL (Asym) that performs high-speed digital communication of several megabits / second using an existing telephone line is used.
metrical Digital Subscriber Line (HDSL) communication system and HDSL (high-bit-rate Digital Subscriber Line)
There is an xDSL communication method such as a communication method. This method uses A
It is standardized in T1.413 of NSI and the like. In these digital communication systems, in particular, the ADSL transmission line and the ISDN transmission line of the TCM-ISDN communication system of the half-duplex communication system are bundled by a middle line and are adjacent to each other. Therefore, ASDL and TCM-ISDN
In at least one of the above, it is necessary to provide a countermeasure for removing interference by an adjacent transmission path.

FIG. 2 shows a configuration of a transmission system of the communication apparatus according to the present invention, for example, shows a configuration of an ATU-C transmission system. The configuration of the transmission system of the ATU-R is the same. In FIG. 2, ATU-C
In the transmission system, the transmission data is multiplexed by a multiplex / sync control (corresponding to the illustrated MUX / SYNC CONTROL) 41, and a cyclic redundancy check (CRC: Cyclic redundancy) is performed on the multiplexed transmission data.
check) 42 and 43 add error detection code, and furthermore, forward error correction (SCRAM & FE
(Corresponding to C) 44 and 45, the addition of the FEC code and the scrambling process are performed.

There are two paths from the multiplex / sync control 41 to the tone ordering 49, one of which is interleave (INTERLEAV).
E) 46 containing an interleaved data buffer (I
nterleaved Data Buffer path, and the other is a fast data buffer (Fast Dat
a buffer) path, and the delay of the interleaved data buffer path for performing the interleave processing becomes larger.

Thereafter, the transmission data is subjected to rate conversion processing by rate converters (equivalent to RATE-CONVERTOR) 47 and 48, and tone ordering (TONE ORDERIN) is performed.
G) At 49, tone ordering processing is performed. And
Constellation encoder gain scaling (CONS) based on the tone-ordered transmission data
The constellation data is created in 50 by TELLATION AND GAIN SCALLING, and the inverse fast Fourier transform unit (IFFT: Inverse Fast Fourier transform) 51
Performs an inverse fast Fourier transform.

Finally, an input parallel / serial buffer (corresponding to INPUT PARALLEL / SERIAL BUFFER) 5
2. The parallel data after the Fourier transform is converted into serial data in 2, and the analog processing and DA
D / A at C (equivalent to ANALOG PROCESSING ANDDAC) 53
The digital waveform is converted to an analog waveform through a converter, and then the data is transmitted through a low-pass filter to a telephone line.

FIG. 3 shows a configuration of a receiving system of the communication apparatus according to the present invention, for example, shows a configuration of an ATU-R receiving system. The configuration of the receiving system of ATU-C is the same. In FIG. 3, ATU-R
The receiving system of, for the received data (transmitted data described above),
Analog Processing and ADC (AN shown)
ALOG PROCESSING AND ADC) Low-pass filter at 141, then convert analog waveform to digital waveform through A / D converter, and time domain equalizer (equivalent to TEQ) 142 for adaptive equalization in time domain Do.

The data subjected to the adaptive equalization processing in the time domain is supplied to an input serial / parallel buffer (IN
PUT SERIAL / PARALLEL BUFFER) 143 converts the serial data into parallel data and converts the parallel data into a fast Fourier transform unit (FFT).
Fast Fourier transform is performed in an ier transform (144), and then adaptive equalization processing in the frequency domain is performed in a frequency domain equalizer (equivalent to FEQ) 145.

Then, the data subjected to the adaptive equalization processing in the frequency domain is provided with a constellation encoder / gain scaling (corresponding to CONSTELLATION AND GAIN SCALLING) 146 and tone ordering (TONE ORDERIN).
G) The data is converted into serial data by the composite processing (maximum likelihood composite method) and tone ordering processing performed in 147, and thereafter, rate conversion processing by rate converters (equivalent to RATE-CONVERTOR) 148 and 149, deinterleaving (DEINTERLEAVE) Deinterleave processing by 150, DESCRAM & FEC 151,
152, FEC (forward error correction) and descrambling, cyclic redundancy check (CRC)
(corresponding to k) CRC (cyclic redundance) by 153, 154
ancy check: cyclic redundancy check), etc., and finally multiplex / sync control (MUX / S shown in the figure)
The received data is reproduced from 155 (equivalent to YNC CONTROL).

In the communication device of the ADSL communication system configured as described above, the ADSL transmission line and the TCM-IS
Mutual interference due to the fact that the DN transmission lines are bundled and adjacent to each other by a collective line on the way is eliminated. Hereinafter, the conventional AD
ADSL interference to TCM-ISDN and ADSL interference that were not considered in the communication device of SL, that is, other ATU-C by ATU-C.
C interference and other ATU-Rs due to ATU-R
A method for removing interference with respect to is described in detail.

First, an outline of the above-described interference removal method will be described with reference to FIG. For example, in the interference cancellation method of the present invention, the ATU-C sets the TTR in its own ATU-C to ISDN
Shifting against TTR only S _1, FEX of the ATU-C
Ensure that T-DS transmissions do not involve ISDN ISDN-US reception. Specifically, TCM-ISDN
In the OCU of ISDN-US, the ISDN-US reception must be performed using the ISDN TTR for the next ISDN-DS transmission.
Ends at a point 7 UI before the rise of.
Therefore, inside the ATU-C, the start of the FEXT-DS transmission, so that after that point, determines the S _1. As a result, the OCU's ISDN-US reception
The interference of the U-C FEXT-DS transmission is eliminated.

In ATU-C, ISDN T
Inside of the TTR was delayed by S ₁ to the TR, ATU
−R with a variable delay S ₂ according to the distance to R
The TTR is transmitted to the U-R. That is, AT
The U-C FEXT-DS transmission conforms to the ISDN ISDN-
In order not to interfere with US reception, ATU
-R FEXT-US transmission is ISDN ISDN-DS
So as not to interference with the reception, to adjust the S ₂ in consideration of the transmission path delay D _1. As a result, the ATU-C F
EXT-DS transmission is performed by another ATU-C FEXT-US
It does not become NEXT noise for reception.

Next, the interference removal method will be described in detail with reference to the drawings. FIG. 4 is a timing chart for explaining in detail the interference elimination method according to the present invention.
In FIG. 4, 1 is ISDN-DS transmission from OCN, 2a and 2b are ISDN-US reception to OCU at distance “0” or long distance limit, respectively.
3 and 5 are ISDN-DS receptions to the DSU at distance "0" or the long distance limit, respectively, and 4 and 6
Is the DSU at the distance “0” or the long distance limit, respectively.
7 is FEXT-DS transmission from ATU-C, and 8 is NEXT transmission from ATU-C.
EXT-DS transmission, 9 is NEXT to ATU-C
-US reception, 10 is FEXT-U to ATU-C
S is reception, 11 is NEXT-US from ATU-R
This is transmission, 12 is FEXT-US transmission from ATU-R, 13 is FEXT-DS reception to ATU-R, and 14 is NEXT-DS reception to ATU-R. Note that the above-mentioned distance “0” is defined as OCU and DSU
The distance between the OCU and the DSU indicates that the distance between the OCU and the DSU is longest.

Hereinafter, the delays S ₁ and S ₂ will be derived from the relational expression between the respective communication services obtained from FIG. First, one cycle of TTR: T (2.5 ms = 276
0 sample = 800 UI), based on the ISDN-DS
Expression (A) is established from the transmission start point: (A) and the FEXT-US reception end point: (A). P _NU + P _FU + S ₁ + S ₂ + 2D _A ≦ T (A) where P _NU is NEXT-US transmission or NEXT-
It indicates the time of US reception (1320 samples), and P _FU is FEXT-US transmission or FEXT-US
It shows the reception time (1288 samples). D _A is a transmission path delay according to the distance, and is 0 to 1
Takes a value of 6UI.

Next, the end point of the ISDN-DS transmission:
From (B) and the start point of FEXT-US reception: (B), equation (B) is established. P _i ≦ P _NU + S ₁ + S ₂ + 2D _A (B) where P _i is the ISDN transmission or reception time (37
7UI).

Next, the end point of the FEXT-DS transmission:
From (C) and the starting point of ISDN-US reception: (C), equation (C) holds. P _FD + S ₁ ≦ P _i + G Equation (C) where P _FD is FEXT-DS transmission or FEXT-
This indicates the DS reception time (1240 samples), and G is 7 UI.

Next, the starting point of FEXT-DS transmission:
From (D) and the end point of ISDN-US reception: (D), equation (D) holds. 2P _i + 2D _i + G ≦ P _FD + P _ND + S ₁ (D) where P _ND is NEXT-DS transmission or NEXT-
Is indicative DS reception time (1472 samples), D _i shows a transmission path delay 16UI long distance limit.

Next, the end point of the FEXT-US transmission:
From (E) and the starting point of ISDN-DS reception: (E), equation (E) holds. P _NU + P _FU + S ₁ + S ₂ + D _A ≦ T (E)

Next, the starting point of the FEXT-US transmission:
From (F) and the end point of ISDN-DS reception: (F), equation (F) is established. _{P i + D i ≦ P NU} + S 1 + S 2 + D A (F) Formula

Next, the starting point of ISDN-US transmission:
From (G) and the end point of FEXT-DS reception: (G), equation (G) is established. P _FD + S ₁ + D _A ≤P _i + G (G)

Next, the end point of the ISDN-US transmission:
From (H) and the start point of FEXT-DS reception: (H), the equation (H) holds. _{2P i + D i + G ≦} P FD + P ND + S 1 + D A (H) formula

Next, the end point of the FEXT-DS transmission:
From (I) and the start point of FEXT-US reception: (I), equation (I) is established. P _FD + S ₁ ≤P _NU + S ₁ + S ₂ + 2D _A Equation (I)

Next, the starting point of FEXT-DS transmission:
From (J) and the end point of FEXT-US reception: (J), equation (J) holds. P _NU + P _FU + S ₁ + S ₂ + 2D _A ≦ P _FD + P _ND + S ₁ (J)

Next, the starting point of FEXT-US transmission:
From (K) and the end point of FEXT-DS reception: (K), equation (K) is established. P _FD + S ₁ + D _A ≤P _NU + S ₁ + S ₂ + D _A (K) formula

Finally, the end point of the FEXT-US transmission:
From (L) and the start point of FEXT-DS reception: (L), equation (L) is established. _{P NU + P FU + S 1} + S 2 + D A ≦ P FD + P ND + S 1 + D A (L) formula

Here, when the variables of the above equation are shifted to the right side in order to find the relationship between S ₂ and D _A and S ₁ , equations (A) to (L) are as follows. _{S 2 + 2D A ≦ T-} P NU -P FU -S 1 (A) formula _{S 2 + 2D A ≧ P i} -P NU -S 1 (B) formula _{S 1 ≦ P i -P FD +} G (C) formula S ₁ ≧ 2P _i −P _FD −P _ND + 2D _i + G (D) Equation S ₂ + D _A ≦ _TP N −P _FU −S ₁ (E) Equation S ₂ + D _A ≧ P _i −P _NU −S ₁ + D _i (F) formula _{D A ≦ P i -P FD -S} 1 + G (G) formula _{D A ≧ 2P i -P FD -P} ND -S 1 + D i + G (H) formula _{S 2 + 2D A ≧ P FD} - P _NU (I) Equation S ₂ + 2D _A ≦ P _FD + P _ND −P _NU −P _FU (J) Equation S ₂ ≧ P _FD −P _NU (K) Equation S ₂ ≦ P _FD + P _ND −P _NU −P _FU (L) expression

In the above equations (A) to (L), when a predetermined value is substituted for a variable, the following equation is obtained. S ₂ + 2D _A ≦ 152 samples−S ₁ (A) expression S ₂ + 2D _A ≧ 377UI-1320 samples −S ₁ (B) expression S ₁ ≦ 384UI-1240 samples (C) expression S ₁ ≧ 793UI−2712 samples (D ) equation S ₂ + D _A ≦ 152 samples -S ₁ (E) where _{S 2 + D A ≧ 393UI-} 1320 samples -S ₁ (F) formula D _A ≦ 384UI-1240 samples -S ₁ (G) where D _A ≧ 777UI −2712 samples −S ₁ (H) formula S ₂ + 2D _A ≦ −80 samples (I) formula S ₂ + 2D _A ≦ 104 samples (J) formula S ₂ ≧ −80 samples (K) formula S ₂ ≦ 104 samples (L )formula

Further, when the variables in the above equations (A) to (L) are converted to μs units, as a result, S ₂ and D
And _A, the following equation is the relationship S ₁ is obtained. S ₂ + 2D _A ≦ 137.68111594 μs-S ₁ (A) Equation S ₂ + 2D _A ≦ −17.527391 μs-S ₁ (B) Equation S ₁ ≦ 76.8115942 μs (C) Equation S ₁ ≦ 21.66038787 μs (D) wherein _{S 2 + D A ≦ 137.6811594μs-} S 1 (E) equation _{S 2 + D A ≦ 32.47282609μs-} S 1 (F) formula _{D A ≦ 76.8115942μs-S 1 (} G) formula D _A ≦ -28. 396791313 μs−S ₁ (H) expression S ₂ + 2D _A ≦ −72.46376812 μs (I) expression S ₂ + 2D _A ≦ 94.20289855 μs (J) expression S ₂ ≦ −72.46768812 μs (K) expression S ₂ ≦ 94.209289855 μs Expression (L) Since the ADSL transmission line delay is always positive, the following conditional expression can be obtained in addition to the above expressions (A) to (L). It can also be. D _A ≧ 0 (M)

Next, S ₁ and S ₂ are determined based on the conditions of the above equations (A) to (M). In the following, two methods for determining the values of S ₁ and S ₂ will be described in detail. First, in the first method, S ₁ is D _A = 16UI
Under the condition of, the point with the least margin among the points: (A) to (M): using (D) and (G),
calculate. By using the equations (D) and (G) having the least margins, it is possible to easily compensate for the conditions of other calculation equations.

For example, assuming that the margin at the point (D) is M _D , M _D can be obtained by the following equation. _{M D = (P FD + P} ND + S 1) - (2P i + 2D i + G) = 2712 samples + S ₁ -793UI ₍₁₎ Formula One, Point: margin When M _G in (G),
M _G may be calculated by the following equation. _{M G = (P i + G} ) - (P FD + S 1 + D A) = 368UI-1240 samples -S ₁ (2) formula

Here, from equations (1) and (2), 2
The sum of two margins. M _D + M _G = 1472 samples-425 UI Expression (3) By performing this processing, S ₁ is erased, and M _D + M _G
There is a constant that does not vary by S _1. this is,
This shows that equalizing the two margins, that is, providing a stable margin for both. Conversely, when one of the margins is increased, the other margin is decreased. Therefore, from this condition, when seek M _D and M _G, the following equation is obtained. _{M D = M G = (M} D + M G) / 2 = (1472 samples -425UI) / 2 (4) equation Here, the point: the (D), point: was equal margin at (G) If the timing setting accuracy is sufficiently high and it is not necessary to secure a large margin, the margin at one of the points may be smaller than the other margin.

[0084] When the obtained equation (4) is substituted for M _G in (2), it is possible to (5) as equation to obtain S _1. Incidentally, the same S ₁ is obtained even by substituting M _D in equation (1). S ₁ = −M _G + 368UI-1240 samples = 24.2743 (μs) Equation (5)

As a result, S ₁ can be fixed.
Accordingly, the conditional expressions (A) to (M) are satisfied,
In addition, if the transmission line delay D _A is 0～16UI,
Thereby obtaining the permissible range of S _2. FIG. 5 shows that D _A is zero.
Is a diagram showing an allowable range of S ₂ when in the range of ～16UI. Note that, as shown in FIG. 5, in the present embodiment, equations (F), (G), (J), and (M)
If the expression is satisfied, all the conditional expressions will be satisfied. That is, (F), (G), (J), and (M)
Portion surrounded by the formula is in a range which can be taken of S _2.

Next, in the first method, S ₂ can be derived from equations (F) and (J) as shown in FIG. Incidentally, S ₂ to obtain here, as shown, the optimum value by the transmission line delay D _A (i.e., (F)
(The margins for equation (J) and equation (J) should be the same.) For example, S ₂ obtained from equation (F) is calculated as follows. S ₂ = P _i + D _i −P _NU −S ₁ −D _A = −D _A +656 samples−187.5 UI Expression (6) On the other hand, S ₂ obtained from Expression (J) is calculated as follows. . _{S 2 = P FD + P ND} + S 1 -P NU -P FU -S 1 -2D A = -D A +104 sample (7)

Therefore, the optimum value of S ₂ indicated by the dotted line (that is, the dotted line in the drawing) can be obtained as shown in equation (8). S ₂ = -1.5D _A + (104 samples Tasu1656 sample _{-187.5UI) / 2 = -1.5D A +51.23415} (μs) (8) Equation

As a result, S ₁ and S ₂ can be calculated from one corresponding equation, ie, equations (5) and (8). In ADSL, S ₁ calculated here is used.
And by shifting the TTR by S ₂ ,
Interference between SL and TCM-ISDN, and AD
All interference between SLs can be eliminated.

Next, a second method for determining the values of S ₁ and S ₂ will be described. Incidentally, S ₁ obtained by the second method is omitted since it is determined by the first method similar to that described above, the description for simplicity.

In the second method, S ₂ is, for example,
As shown in FIG. 6, there are three values of and. This makes it possible to eliminate the interference of the ADSL with the TCM-ISDN and the interference between the ADSLs, and further, it is possible to fix S ₂ to three values, and accordingly, as in the first method, it is not necessary to obtain the S ₂ by calculation of the formula, the calculation amount is reduced, high-speed processing is facilitated. In communication,
By making the relatively rare case and an optional function, S ₂ can be set to 0 μs, that is, S ₂ can be eliminated (fixed to one value), and more efficient communication can be performed.

[0091] However, in order to realize the above-mentioned interference cancellation method is the premise that it is possible to measure the transmission line delay D _A. That is, if D _A cannot be determined, S ₁
And it is impossible to determine the S _2. Therefore, in the interference elimination method of the present invention, this measure is taken without measuring the ISDN distance by measuring the delay between the ATU-C and the ATU-R. That is, in the interference cancellation method of the present invention, by measuring the delay between ATU-C and ATU-R, wherein the can measure the transmission path delay D _A.

For example, in the ADSL communication system, A
In the TU-C, according to the initialization sequence shown in FIG.
First, a pilot signal (C-PILOT1) for synchronization is first transmitted to the ATU-R. In addition, TTR is also included in this. And ATU-C
Then, reverb (C-REVERB1), C-PILO
Signals are transmitted to the ATU-R one after another in the order of T2,.

In order to perform the above sequence,
ATU-C and ATU-R correspond to the “Beginning of Hyp
at a point er frame ", it is necessary to hyperframe synchronization is established. Therefore, the ATU-C, prior to that point in advance to calculate the S ₁ and S _2, a predetermined time TTR, i.e., It must be shifted by S ₁ and S ₂ .

Therefore, in ATU-C, the illustrated C-QUA
In the section of IET2, a specific signal for measuring the round trip time (hereinafter referred to as an RTD signal) is transmitted, a response from the ATU-R to the transmission signal is waited, and the delay time, that is, the RTD (Round) Measure Trip Delay). Specifically, as shown in FIG. 8B, the ATU-C
However, for example, the ATU-R transmits a signal inverted for each symbol on the carrier of the tone 16, and in response, the ATU-R responds to the signal inverted for each symbol on the carrier of the tone 32 which is twice the frequency. Reply. And
For example, by detecting a change in the phase of the returned signal, that is, by detecting a point where the phase changes by 180 degrees, the edge of the response signal is recognized, and the RTD is measured.

Note that the tone 16 and the tone 32 shown in FIG.
Is a sine wave having a low frequency for convenience of explanation, but this signal is actually a signal having a higher frequency. The tone to be used is not limited to this, and any tone may be used as long as the frequency is different between the forward path and the return path. Further, the RTD may be measured by a method other than the phase detection.

The above method has two advantages in measuring the RTD. First, since the calculation by this method is very easy, the processing time by the ATU-R is short. Also,
Second, by performing communication at twice the frequency, the frequency does not overlap between uplink and downlink, so that the ATU-C can easily recognize the signal from the ATU-R.

Therefore, in ATU-C, the pre-delay time from the transmission of the RTD signal to the response is DL (1), and A
Assuming that the operation delay time in the TU-R is DL (2) (FIG. 8)
(A) refer), the transmission path delay D _A one-way of obtaining, (DL
(1) -DL (2)) / 2 can be easily obtained.

Thus, ATU-C and ATU-R
There before starting synchronization hyperframe, the ATU-C, it is possible to obtain the transmission path delay D _A, accompanied, TT
S ₁ and S ₂ for delaying R can be easily obtained.

Embodiment 2 Above, in the description up to this point, based on the value of the transmission path delay D _A, it has been to calculate the S ₁ and S ₂ for delaying the TTR, thereafter, regardless of the transmission path delay D _A, S ₁ And how to calculate S ₂ will be described.

First, the condition of the above equation (D) is changed to the following equation (D) ′. T (indicating one cycle of TTR) ≦ P _FD + P _ND + S ₁ (D) ′ Equation By changing the equation (D), the point:
The interference in (D) can be completely removed. Therefore,
When calculating the condition of S ₁ on the basis of (D) 'equation can be expressed as the following equation. _{S 1 ≧ T-P FD -P} ND ≧ 2760 samples -1240 samples -1472 samples ≧ 48 samples (D) 'formula

Further, the ODN and the ADS of the ODN
In many cases, the L-station-side device ATU-C is installed in the same station (see FIG. 14A).
Terminal device DSU and ADSL terminal device ART-R
14 (b) and 14 (c). That is, the equations (F) and (G) are rewritten as follows. P _i + D _i ≤P _NU + S ₁ + S ₂ + D _A + (Delay from ATU-R to DSU) ≤P _NU + S ₁ + S ₂ + D _A + (D _i -D _A ) S ₂ ≧ 377UI-1320 samples-S ₁ (F) 'equation _{P FD + S 1 + D a} ≦ P i + G + ( delay from DSU to _{ATU-R) ≦ P i +} G + D a S 1 ≦ 384UI-1240 sample (G)' formula

Accordingly, under the condition of S ₁ , under the condition of D _A = 20 UI (showing the maximum value of D _A , which may be set to 16 UI as described above), the point: (A) to the point: (M) Calculate by using (D) and (G), the point with the least margin in the inside. By using the equations (D) ′ and (G) ′ with the smallest margin, it is possible to easily compensate for the conditions of other calculation equations.

For example, if the margin at the point (D) is M _D ′, M _D ′ can be obtained by the following equation. _{M D '= (P FD +} P ND + S 1) -T (1)' type whereas the point: the margin at (G) 'When, M _G' M _G may be calculated by the following equation. However, D _A = 20 UI. _{M G '= (P i +} G + D A) - (P FD + S 1 + D A) (2)' equation

Here, by the same procedure as the first method described above, the sum of two margins is obtained from the equations (1) ′ and (2) ′, and M _D ′ + M _G ′ is calculated by S ₁ Calculate to be a constant that does not fluctuate. Then, M _D ′ and M _G ′ are obtained from the following equations, as described above. _{M D '= M G' =} (M D '+ M G') / 2 (4) ' equation Here, the point: the (D), point: was equal margin at (G), setting the timing Is sufficiently high and it is not necessary to secure a large margin, the margin at one of the points may be smaller than the other margin.

Then, the value obtained by the equation (4) ′ is expressed as M _G
Is substituted into the expression (2) ′, the expression (5) ′ gives S ₁
Can be obtained. Incidentally, the same S ₁ is obtained even by substituting 'the (1)' M _D in formula. _{S 1 = 54.3325 (μs) (} 5) ' equation Thereby, S ₁ does not depend on fluctuations of the transmission path delay D _A, it is possible to fix the value.

On the other hand, under the condition that D _A = 20 UI (or 16 UI as described above), S ₂ is a point:
Point: The point with the least margin in (M):
Calculation is performed using (A) and (K). In addition,
By using the equations (A) and (K) having the least margins, it is possible to easily compensate for the conditions of other calculation equations.

For example, assuming that the margin at point (A) is M _A , M _A can be obtained by the following equation. However, D _A = 20 UI. M _A = T− (P _NU + P _FU + S ₁ + S ₂ + 2D _A ) (11) On the other hand, if the margin at the point: (K) is M _K ,
M _K can be obtained by the following equation. However, D _A
= 20 UI. M _K = (P _NU + S ₁ + S ₂ + D _A ) − (P _FD + S ₁ + D _A ) (12)

Here, in the same procedure as the first method described above, the sum of the two margins is obtained from equations (11) and (12), and M _A + M _K is varied by S _2. Calculate to be no constant. And M _A and M
_K is obtained from the following equation as described above. M _A = M _K = (M _A + M _K ) / 2 Equation (14) Here, the margin at the point: (A) is equal to the margin at the point: (K), but the timing setting accuracy is sufficient. If it is high and it is not necessary to secure a large margin, the margin at either point may be smaller than the other margin.

Then, M _K obtained by the equation (14)
By substituting into Equation (12), S ₂ can be obtained as Equation (15). Even by substituting M _A (11) where the same S ₂ is obtained. _{S 2 = -48.8076 (μs) (} 15) Thus equation, similarly to S ₂ also S _1, regardless of the variation of the transmission path delay D _A, it is possible to fix the value.

In the description of the above embodiment, all the conditional expressions include, for convenience of explanation, each device, that is,
A margin due to an internal calculation delay in the ATU-C, ATU-R, OCU, and DSU is not included. Therefore, by including this margin in each conditional expression,
Furthermore, highly accurate S ₁ and S ₂ can be obtained.
The conditional expression and the numerical value in the present embodiment are S ₁
And S ₂ are examples for calculating, and, for example, by combining more optimal conditional expressions and numerical values in consideration of changes in use conditions and communication environment, etc., more accurate S ₁ and S ₂ can be obtained. You may get it.

Embodiment 3 As described above, in the first embodiment,
Transmission line delay D_ATo delay TTR based on the value of
S₁And S_TwoEmbodiment 2 about the method of calculating
Then, the transmission path delay D _ARegardless of₁And S_TwoCalculate
We have explained how to do this. In this embodiment
Is different from the interference removal method in the second embodiment.
Explanation of the interference removal method when a new condition is added to
You. That is, here, based on the new condition,
Expressions (A) to (L), which are the relational expressions between the respective communication services,
To shift the timing of TTR by rebuilding
S₁And S_TwoIs calculated.

Here, the newly added condition will be described.
I will tell. First, loop timing in ATU-R
Margin: M_LOIs introduced. Loop timing merge
N: M _LOMeans the error of ATU-R transmission timing.
Margin, for example, received from ATU-C.
When the TTR in ATU-R is generated from the TTR
This is the delay that occurs when Second, ATU-C and A
System margin in TU-R: M_SYSIntroduce
You. System margin: M_SYSAre ATU-C and
Marker taking into account the accuracy error of ATU-R transmission timing
Gin, for example, delays caused by internal arithmetic processing, etc.
It is. Third, guard interval in ISDN
Le: G_TConsider. Guard interval: G_TIs the IS
To more strictly compensate for interference with the DN,
Here, compensation is also made for this period. Fourth, IS
To compensate for mutual interference between DN and ADSL
The transmission / reception over the TTR cycle is prohibited (see FIG. 15).
(D) and (H)). Fifth, ATU-C to ATU
-If the distance to R is equal to the distance from OCU to DSU
Set. Sixth, the transmission path delay D in the second embodiment_A
= 20 UI condition D_A= 18.5 UI.

In the present embodiment, the above relational expression is changed based on these conditions. FIG. 15 is a timing chart for explaining in detail the interference elimination method according to the present invention. FIG. 4 in the first embodiment described above.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. The variables used in the relational expressions are the same as those in the first and second embodiments, unless otherwise specified.

First, one cycle of TTR: T (2.5 ms =
2760 samples = 800 UI)
From the start point of DS transmission: (A) and the end point of FEXT-US reception: (A), the expression (A ′) is established. P _NU + P _FU + S ₁ + S ₂ + 2D _A + M _LO + 2M _SYS ≦ T (A ′) where the transmission path delay D _A is a transmission path delay according to the distance, but a fixed value of 18.5 UI is used. Also, M _LO =
It is assumed that 4.5 μS and M _SYS = 2.89 μS.

Next, the IS including the guard interval
End point of DN-DS transmission: (B) and FEXT-US
Starting point of reception: From (B), the equation (B ') holds. _{P i + G T ≦ P NU} + S 1 + S 2 -M LO -2M SYS (B') equation However, the guard interval: G _T shall be 6 UI.

Next, the end point of the FEXT-DS transmission:
From (C) and the starting point of ISDN-US reception including the guard interval: (C), the expression (C ′) is established. P _FD + S ₁ + M _SYS ≦ P _i (C ′)

Next, the starting point of FEXT-DS transmission:
(D) and the end point of ISDN-US reception including the condition of prohibiting transmission / reception over the TTR cycle: From (D),
Equation (D ') holds. T ≦ P _FD + P _ND + S ₁ −M _SYS (D ′)

Next, the end point of the FEXT-US transmission:
From (E) and the starting point of ISDN-DS reception: (E), the equation (E ') holds. P _NU + P _FU + S ₁ + S ₂ + M _LO + 2M _SYS ≦ T (E ′)

Next, the starting point of FEXT-US transmission:
From (F) and the end point of ISDN-DS reception including the guard interval: (F), the formula (F ′) is established. P _i + G _T ≤P _NU + S ₁ + S ₂ −M _LO −M _SYS (F ′)

Next, the ISD including the guard interval
From the start point of N-US transmission: (G) and the end point of FEXT-DS reception: (G), the expression (G ′) is established. P _FD + S ₁ + M _SYS ≦ P _i (G ′)

Next, the end point of the ISDN-US transmission including the condition for prohibiting the transmission and reception over the TTR cycle:
From (H) and the start point of FEXT-DS reception: (H), the expression (H ′) is established. T ≦ P _FD + P _ND + S ₁ −M _SYS (H ′) Formula

Next, the end point of the FEXT-DS transmission:
From (I) and the start point of FEXT-US reception: (I), equation (I ′) is established. _{P FD + S 1 + M SYS} ≦ P NU + S 1 + S 2 -M LO -2M SYS (I') formula

Next, the starting point of FEXT-DS transmission:
From (J) and the end point of FEXT-US reception: (J), the equation (J ') holds. P _NU + P _FU + S ₁ + S ₂ + 2D _A + M _LO + 2M _SYS ≦ P _FD + P _ND + S ₁ −M _SYS (J ′)

Next, the starting point of the FEXT-US transmission:
From (K) and the end point of FEXT-DS reception: (K), the equation (K ′) holds. _{P FD + S 1 + M SYS} ≦ P NU + S 1 + S 2 -M LO -2M SYS (K') formula

Finally, the end point of the FEXT-US transmission:
From (L) and the start point of FEXT-DS reception: (L), the expression (L ') holds. _{P NU + P FU + S 1} + S 2 + M LO + 2M SYS ≦ P FD + P ND + S 1 -M S (L') formula

Then, by substituting the predetermined numerical value defined above into the above relational expression and obtaining the relationship between S ₁ and S ₂ , FIG.
The relationship shown in FIG. That is, as shown, the equations (A '), (B'), (C '), (D')
Formula, (F ') Formula, (G') Formula, (H ') Formula, and (J
The range enclosed by the expression ') is the range that S ₁ and S ₂ can take.

Here, D _A = 18.5 UI defined earlier.
Under the condition, the point with the least margin among the points: (A) to (M): using (A) and (F),
Calculate the approximate range of S ₁ and S ₂ . That is,
Using the equations (A ′) and (F ′) having the least margins, one condition for compensating the other equations is calculated.

For example, assuming that the margin at the point (A) is M _A , M _A can be obtained by the following equation. M _A = T− (P _NU + P _FU + S ₁ + S ₂ + 2D _A + M _LO + 2M _SYS ) = 2.5 ms− (2608 samples + S ₁ + S ₂ + 37UI + 10.28 μS (16) On the other hand, the point: margin at (F) Let M _F be
M _F can be obtained by the following expression. _{M F = (P NU + S} 1 + S 2 -M LO -M SYS) - (P i + G T) (17) Equation

Next, in the same procedure as that of the first embodiment described above, the sum of the two margins is obtained from the equations (16) and (17), and approximate S ₁ and S ₂ are obtained from M _A + M _F.
Calculate the range of M _A and M _F are obtained from the following equations. M _A = M _F = (M _A + M _F ) / 2 Equation (18) Then, M _A obtained from Equation (18) is expressed by Equation (16).
Substituting into the formula, S ₁ with the largest margin
And it is possible to obtain the relationship between S _2.

Next, S ₁ is fixed based on the relationship shown in FIG. Here, S ₁ is the intermediate value between the expressions (D) and (C), that is, S ₁ = (46, 37 + 52.05) ÷ 2
= 49.21 (μs). On the other hand, S ₂ is obtained as follows by substituting S ₁ into the previously calculated equation (17). S ₂ = −38.04 (μs)

As described above, in the present embodiment, by adding a new condition, S ₁ and S ₂ can be calculated with higher accuracy as compared with the above-described embodiment. It is possible to accurately remove interference between devices. In the present embodiment, S ₁ and S ₂ having the largest margins have been obtained. However, the present invention is not limited to these values, and any value may be used as long as it is within the range of the relationship shown in FIG. In Embodiments 1 and 2, the AT
While the TTR to U-R were allowed only S ₂ shifts at ATU-C, in the present embodiment, choosing a device that performs shift of TTR, ATU-C, either ATU-R is TTR Will be shifted.

[0132]

As described above, according to the present invention, for example, the own communication device (ATU-C) can
The TTR (reference signal) in C is shifted by S ₁ (first predetermined time), and the FEXT-DS of ATU-C
(Other communication systems) Do not start ISDN-US reception. Moreover, the ATU-C, and imparted to the inside of the TTR delayed earlier by S _1, variable delay corresponding to the distance between the ATU-R S ₂ (second predetermined time), ATU-
The TTR is transmitted to R (a communication partner device). That is, the AEXT-C FEXT-DS transmission is not synchronized with another ATU (hyperframe synchronization).
So as not to interference with FEXT-US reception of -C, adjusting the S _2. As a result, ADSL and IS
There is an effect that all interference between DNs and between ADSLs can be eliminated.

According to the next invention, the first predetermined time is:
Under the condition of the maximum transmission path delay, the calculation is performed using an equation that is most likely to cause interference, that is, an equation having the least margin among the relational equations. As a result, there is an effect that other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated.

According to the next invention, S ₁ (first predetermined time) and S ₂ (second predetermined time) can be uniquely calculated from one corresponding relational expression. The TTR (reference signal) is shifted by the calculated S ₁ and S ₂ . As a result, ADSL and IS
This has the effect of eliminating all interference between DNs and interference between ADSLs.

According to the next invention, S ₂ (second predetermined time) is fixed to a value satisfying an allowable range in advance. This allows ADSL interference to ISDN, and A
DSL interference can be eliminated,
Further, S ₂ can be fixed to a plurality of values, and it is not necessary to calculate S ₂ by the operation of the relational expression. Therefore, there is an effect that the amount of calculation is reduced and the processing speed is accelerated. In the communication, by the S ₂ to be relatively rare case (a value close to the maximum value and the minimum value of the allowable range) as an optional feature, can be fixed to S ₂ to one, further, the calculation amount is reduced This has the effect of accelerating the processing speed.

According to the next invention, ATU-C and A
Before the TU-R establishes hyperframe synchronization, the AT
UC calculates the transmission path delay. Thereby, TTR
S ₁ (first predetermined time) for delaying (reference signal)
And S ₂ (the second predetermined time) can be easily obtained, and the communication can be established without interference.

According to the next invention, since the RTD (round-trip time of a specific signal) is measured, the calculation is very easy, and the processing time by the ATU-R is reduced. Also, for example, if the frequency of the return path is 2
By performing the communication twice, the frequency does not overlap between the uplink and the downlink, so that the ATU-C can easily recognize the signal from the ATU-R.

According to the next invention, for example, the own communication device (ATU-C) shifts the TTR (reference signal) in the own ATU-C by S ₁ (first predetermined time), and the ATU-C
FEXT-DS does not start ISDN-US reception of ISDN (another communication system). Also, A
In TU-C, the internal TTR delayed by S1 _first
The TTR is transmitted to the ATU-R (communication partner device) with a variable delay S ₂ (second predetermined time) according to the distance from the ATU-R. That is, ATU
-C FEXT-DS transmission is not synchronized (hyperframe synchronization) with another ATU-C FEXT-US
So as not to interference with reception, adjust the S _2.
As a result, there is an effect that all interference between ADSL and ISDN and between ADSL can be eliminated.

According to the next invention, the first predetermined time is:
Under the condition of the maximum transmission path delay, the calculation is performed using an equation that is most likely to cause interference, that is, an equation having the least margin among the relational equations. As a result, there is an effect that other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated.

According to the next invention, S ₁ (first predetermined time) and S ₂ (second predetermined time) can be uniquely calculated from one corresponding relational expression. The TTR (reference signal) is shifted by the calculated S ₁ and S ₂ . As a result, ADSL and IS
This has the effect of eliminating all interference between DNs and interference between ADSLs.

According to the next invention, S ₂ (second predetermined time) is fixed to a value satisfying the allowable range in advance. This allows ADSL interference to ISDN, and A
DSL interference can be eliminated,
Further, S ₂ can be fixed to a plurality of values, and it is not necessary to calculate S ₂ by the operation of the relational expression. Therefore, there is an effect that the amount of calculation is reduced and the processing speed is accelerated. In the communication, by the S ₂ to be relatively rare case (a value close to the maximum value and the minimum value of the allowable range) as an optional feature, can be fixed to S ₂ to one, further, the calculation amount is reduced This has the effect of accelerating the processing speed.

According to the next invention, ATU-C and A
Before the TU-R establishes hyperframe synchronization, the AT
UC calculates the transmission path delay. Thereby, TTR
S ₁ (first predetermined time) for delaying (reference signal)
And S ₂ (the second predetermined time) can be easily obtained, and the communication can be established without interference.

According to the next invention, since the RTD (round-trip time of a specific signal) is measured, the calculation is very easy, and the processing time by the ATU-R is reduced. Also, for example, if the frequency of the return path is 2
By performing the communication twice, the frequency does not overlap between the uplink and the downlink, so that the ATU-C can easily recognize the signal from the ATU-R.

According to the next invention, in each of the communication devices, the first and second predetermined times are set to be the most likely to cause interference regardless of the condition of the transmission line delay, that is, the most margin in the relational expression. Calculate using the relational expression of few points. As a result, there is an effect that other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated. Also,
Since the first and second predetermined times are fixed values, the value does not need to be changed each time depending on conditions such as a transmission path delay, so that the amount of calculation of each device can be reduced. Play.

According to the next invention, the first and second predetermined times are determined by the relational expression of the point where interference is most likely to occur, that is, the point having the least margin in the relational expression, regardless of the condition of the transmission line delay. Is calculated using As a result, there is an effect that other conditions, for example, a relational expression between devices that are less likely to cause interference can be easily compensated. In addition, since the first and second predetermined times are fixed values, the value does not need to be changed each time due to conditions such as a transmission line delay, so that the calculation amount of each device can be reduced. It works.

According to the next invention, in the communication apparatus, for example, a loop timing margin, a system margin, a guard interval in ISDN, TT
By adding a new condition such as a condition for prohibiting transmission and reception over the R period, the first predetermined time and the second
Is calculated. Thereby, it is possible to calculate the first predetermined time and the second scheduled time with higher accuracy, and it is possible to more accurately remove interference between the devices.

According to the next invention, the first predetermined time and the second predetermined time are, for example, a loop timing margin, a system margin, a guard interval in ISDN, a condition for inhibiting transmission and reception over the TTR cycle, and the like. It is calculated based on a relational expression to which a new condition is added. Thereby, the first predetermined time with higher accuracy,
In addition, the second scheduled time can be calculated, and accordingly, the interference between the devices can be more accurately removed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an interference removal method according to the present invention.

FIG. 2 is a diagram showing a configuration of a transmission system of the communication device according to the present invention.

FIG. 3 is a diagram showing a configuration of a receiving system of the communication device according to the present invention.

FIG. 4 is a timing chart for explaining in detail an interference elimination method according to the present invention.

5 is a diagram showing an allowable range of S ₂ when the transmission line delay D _A is in the range of 0～16UI, the value of S ₂ obtained by the first method.

6 is a diagram showing an allowable range of S ₂ when the transmission line delay D _A is in the range of 0～16UI, the value of S ₂ obtained by the second method.

FIG. 7 is a diagram showing an initialization sequence in ADSL.

FIG. 8 is a diagram illustrating a method for calculating a transmission path delay.

FIG. 9 is a diagram showing a signal flow in a TCM-ISDN service.

FIG. 10 is a diagram for explaining NEXT noise and FEXT noise.

FIG. 11 is a diagram showing a symbol format of a hyperframe in ADSL.

FIG. 12 is a diagram showing a symbol format of a hyperframe in ADSL.

FIG. 13 is a diagram for explaining interference between ADSLs.

FIG. 14 is a diagram illustrating a configuration of a communication system.

FIG. 15 is a timing chart for explaining in detail the interference elimination method according to the present invention.

FIG. 16 is a relationship diagram between S ₁ and S ₂ obtained from a relational expression.

[Explanation of symbols]

1 ISDN-DS transmission, 2a, 2b ISDN-US
Reception, 3,5 ISDN-DS reception, 4,6 ISDN
-US transmission, 7 FEXT-DS transmission, 8 NEXT-
DS transmission, 9 NEXT-US reception, 10 FEXT-
US reception, 11NEXT-US transmission, 12 FEXT-
US transmission, 13 FEXT-DS reception, 14 NEXT
-DS reception.

Claims (16)

[Claims] 1. A communication for establishing a mutual synchronization and transmitting data by ADSL by transmitting a reference signal for synchronization with respect to a downstream and an upstream and transmitting the reference signal to a communication partner device. In the device, the same characteristic can be obtained by delaying the reference signal in its own communication device by a first predetermined time, and further adjusting the reference signal to be transmitted to the communication partner device back and forth by a second predetermined time. Another communication system that uses a line having the same and performs communication using the same reference signal;
A communication apparatus characterized in that all mutual interference occurring between ADSL and all mutual interference occurring between ADSL are eliminated. 2. An allowable range for a first predetermined time is calculated based on a relational expression between a communication device on the transmission side and a communication device on the reception side where interference is most likely to occur, and a margin of the allowable range is maximized. The communication device according to claim 1, wherein the value is fixed as the first predetermined time. 3. The range of the transmission path delay to be compensated is determined from the relational expressions of all the transmitting side communication apparatuses and the receiving side communication apparatuses which may cause interference and the first predetermined time. And calculating a value that always maximizes a margin in accordance with the fluctuation of the transmission path delay, and using the calculated value as the second predetermined time. The communication device according to claim 2, wherein 4. The range of the transmission path delay to be compensated is determined from the relational expressions of all the transmitting side communication apparatuses and the receiving side communication apparatuses which may cause interference and the first predetermined time. A second predetermined time allowable range corresponding thereto is calculated, and the second predetermined time is fixed within the second predetermined time allowable range even when the transmission path delay fluctuates. Item 3. The communication device according to item 2. 5. Before establishing communication between devices in ADSL, measurement of a transmission path delay between the devices and the first
The communication device according to claim 3, wherein the predetermined time and the second predetermined time are calculated, and communication is established without interference. 6. The communication device according to claim 5, wherein the transmission path delay is calculated based on a round trip time of a specific signal between the devices. 7. ADSL having a reference signal for synchronization with respect to a downstream and an upstream.
In the method for removing interference in a communication device performing data communication according to the above, the reference signal in the own communication device is delayed by a first predetermined time, and further, the reference signal to be transmitted to a communication partner device is delayed by a second predetermined time. By making adjustments, all mutual interference occurring between the ADSL and other communication systems that use lines having the same characteristics and perform communication using the same reference signal, and between the ADSL, An interference elimination method characterized by eliminating all generated mutual interference. 8. An allowable range for a first predetermined time is calculated based on a relational expression between a transmitting side communication apparatus and a receiving side communication apparatus where interference is most likely to occur, and a margin of the allowable range is maximized. The method according to claim 7, wherein the value is fixed as the first predetermined time. 9. The range of the transmission path delay to be compensated is determined based on the relational expressions of all transmission side communication apparatuses and reception side communication apparatuses which may cause interference and the first predetermined time. And calculating a value that always maximizes a margin in accordance with the fluctuation of the transmission path delay, and using the calculated value as the second predetermined time. The interference removal method according to claim 8, wherein 10. The range of the transmission path delay to be compensated is determined based on the relational expressions of all the communication apparatuses on the transmission side and the communication apparatus on the reception side, which may cause interference, and the first predetermined time. A second predetermined time allowable range corresponding thereto is calculated, and the second predetermined time is fixed within the second predetermined time allowable range even when the transmission path delay fluctuates. Item 9. The interference removal method according to Item 8. 11. Before establishing communication between devices in ADSL, measurement of a transmission path delay between the devices and calculation of the first predetermined time and the second predetermined time are performed, and in a state where there is no interference. 10. The communication according to claim 9, wherein the communication is established.
Or the interference removal method according to 10. 12. The method according to claim 11, wherein the transmission path delay is calculated based on a round trip time of a specific signal between the devices. 13. An allowable range for a first predetermined time is calculated based on a relational expression between a transmitting-side communication device and a receiving-side communication device in which interference is most likely to occur, and a margin of the allowable range is maximized. The value is fixed as a first predetermined time, and the fixed first predetermined time is substituted into all the relational expressions. In this state, the communication between the transmitting side communication device and the receiving side where interference is most likely to occur. 2. The apparatus according to claim 1, wherein an allowable range of the second predetermined time is calculated based on a relational expression with the apparatus, and a value that maximizes a margin of the allowable range is fixed as the second predetermined time. Communication device. 14. An allowable range for a first predetermined time is calculated based on a relational expression between a transmitting-side communication device and a receiving-side communication device in which interference is most likely to occur, and a margin of the allowable range is maximized. The value is fixed as a first predetermined time, and the fixed first predetermined time is substituted into all the relational expressions. In this state, the communication between the transmitting side communication device and the receiving side where interference is most likely to occur. 8. The apparatus according to claim 7, wherein a permissible range of the second predetermined time is calculated based on a relational expression with the apparatus, and a value that maximizes a margin of the permissible range is fixed as the second predetermined time. Interference removal method. 15. A newly added delay caused by internal processing in a communication device on a transmission side and a reception side and a predetermined condition for more strictly protecting the other communication system from interference are added to the relational expression. 14. The communication device according to claim 13, wherein the first predetermined time and the second predetermined time are calculated based on a relational expression reflecting those conditions. 16. A delay newly added to the relational expression due to internal processing in a communication device on a transmission side and a reception side and a predetermined condition for more strictly protecting the other communication system from interference. The method according to claim 14, wherein the first predetermined time and the second predetermined time are calculated based on a relational expression reflecting those conditions.