JP2017208724A - Digital information transmission system and transmitter and method used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform information transmission with high throughput even under an environment in which there are disturbing waves.SOLUTION: A digital information transmission system transmits digital information from a transmitter to a receiver by using at least one carrier frequency. The transmitter includes: estimation means for estimating duration and an occurrence period of an electromagnetic disturbing wave having strength exceeding a threshold value for each carrier frequency; determination means for determining a transmission method on the basis of comparison of throughput corresponding to the estimated duration and occurrence period with a guarantee value for each carrier frequency; and transmission means for performing transmission in accordance with the determined transmission method.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a digital information transmission system that transmits digital information by transmitting electrical signals.

  In a digital information transmission system such as ADSL (Asymmetric Digital Subscriber Line) using a metal line as a communication transmission path, electromagnetic waves emitted from a medium other than the system (electromagnetic waves used for other communications and broadcasting, surrounding electric / electronics, etc.) The electromagnetic wave emitted from the device is coupled onto the communication transmission path, and affects the electric signal transmitted through the communication transmission path (electromagnetic interference) as a conductive electromagnetic interference wave. This may cause communication quality degradation such as transmission information errors and omissions. In order to avoid this, a general digital information transmission system has an error detection / correction function for correcting an error occurring in information to be transmitted.

  For example, in a conventional digital information transmission process in ADSL having an error detection and correction function, digital information transmitted from an information transmission apparatus such as a server is encoded by CRC (Cyclic Redundancy Code) encoding, read / read in an ADSL transmitter. Solomon (Reed-Solomon Code: RS) coding, scramble processing, trellis coding, DAM (Discrete Multi-tone) modulation including QAM (Quadrature Amplitude Modulation) and IFFT (Inverse Fast Fourier Transform), CP (Cyclic Prefix) addition After the processing is sequentially performed, the signal is converted into an analog signal by AFE (Analog Front End) processing and output as an electrical signal to the transmission path. On the other hand, in an ADSL receiver, an electric signal (analog multiple wave) transmitted from a transmission path is converted into a digital signal by AFE processing, and waveform equalization on the time axis is performed by TEQ (Time domain Equalizer). Subsequently, DMT demodulation processing by CP deletion and FFT is performed, and waveform equalization processing FEQ (Frequency domain Equalizer) on the frequency axis is performed. In the QAM demodulation process included in the DMT demodulation process, Euclidean distance information from each QAM constellation point of the received signal read from each frequency component of the analog multiplexed wave is calculated, and this is passed to the Viterbi decoder. The Viterbi decoder performs symbol determination of the received signal based on the Euclidean distance information. Thereafter, after descrambling processing and RS decoding, it is confirmed whether or not there is an error in the information after symbol determination by CRC check, and transmitted to a receiving terminal such as a personal computer (PC). At this time, if information that could not be corrected by error correction remains at a predetermined rate, the information is generally discarded.

  Thus, in the information transmission / reception process in ADSL, as described above, error detection and correction are performed by CRC encoding / checking, RS encoding / decoding, scrambling / descrambling, and trellis encoding / Viterbi decoding. Combining these features makes it possible to establish communications that are highly resistant to jamming waves in the transmission system, that is, that do not easily cause transmission errors.

  Furthermore, in DMT (multi-carrier transmission system), a maximum of 15 bits is assigned to each of a plurality of subcarriers (bins) between an ADSL modem and a DSLAM (Digital Subscriber Line Access Multiplexer). At that time, a relatively small number of bits are allocated to bins having a large influence of the disturbing wave, and a relatively large number of bits are allocated to a bin having a small influence of the disturbing wave. For example, in Non-Patent Document 1, the communication transmission path is monitored (training) at the time of establishing a link between an ADSL modem and DSLAM, the intensity of the signal and interference wave is confirmed for each bin, and the amount of bits to be put on each bin is set. Determining (bitmap) is disclosed.

Shigenori Yuasa, Shuichiro Asagi, “A lot of advanced technology is revealed in a small box, revealing the inside of ADSL modem”, Nikkei NETWORK, pp. 194-199, 2002. 08

  However, since only a small number of bits can be assigned to bins that are greatly affected by interference, the amount of bits to be transmitted is reduced accordingly. That is, in the presence of an interference wave, throughput is inevitably lowered as a result of adopting a method of reducing symbol determination errors by reducing the amount of information to be transmitted.

  Even if the error detection and correction function is provided, the error cannot always be completely corrected if the intensity of the interference wave is large and a sufficient signal-to-noise ratio (S / N ratio) cannot be obtained. As a result, the number of frames discarded in the CRC check in the ADSL transceiver increases, so that the throughput also decreases in this case.

  The present invention has been made by paying attention to the above circumstances, and the object of the present invention is a digital information transmission system capable of performing high-throughput information transmission even in an environment where interference waves exist, and the system. It is to provide a transmitter and a method used in the above.

  In order to solve the above-described problem, an aspect of the present invention is a digital information transmission system that transmits digital information from a transmitter to a receiver using at least one carrier frequency, and the transmitter includes the carrier wave. Estimating means for estimating the duration and generation period of electromagnetic interference having an intensity exceeding a threshold for each frequency, and a throughput and a guarantee value corresponding to the estimated duration and generation period for each carrier frequency A determination unit that determines a transmission method based on the comparison and a transmission unit that performs transmission according to the determined transmission method are provided.

  According to another aspect of the present invention, in the determination unit, the carrier frequency for which the throughput exceeds the guaranteed value is transmitted at a time when the electromagnetic interference does not exist, and the carrier frequency for which the throughput is less than the guaranteed value. The transmission method is determined so that transmission is performed both at the time when the electromagnetic interference wave exists and at the time when the electromagnetic interference wave does not exist.

  According to the present invention, it is possible to perform information transmission with high throughput even in an environment where an interference wave exists.

The figure which shows the example of an experimental result which shows the relationship between the duration of a bursty jamming wave, and a throughput used for the principle explanation of the present invention. The figure which shows the example of the modulation interval of an ADSL frame used for description of the principle of this invention, and the application timing of a bursty interference wave. 1 is a block diagram showing an example of a digital information transmission system according to a first embodiment of the present invention. The block diagram which shows the transmission processing example of the digital information in ADSL. The functional block diagram which shows the digital information transmission process part shown in FIG. 3 in detail. The figure which shows an example of the time series data of an interference wave signal. The sequence diagram which shows an example of the digital information transmission process in the digital information transmission system of FIG. 4 is a flowchart showing an operation example of the transmitter shown in FIG. 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[principle]
In general, the interference wave has a certain width in the frequency band, and when viewed on the time axis, the duration is also wide, and the generation timing varies. A typical interference wave in an electromagnetic environment is an interference wave of a power supply system. Such an interference wave has a substantially constant frequency, period and intensity. The present inventors pay attention to the case where the intensity of the jamming wave has a periodicity in time, and the jamming wave generated in a burst manner, that is, between the duration of the bursty jamming wave and its generation period and the throughput. In order to clarify the relationship, SW (Sinusoidal Wave) pulse-modulated wave simulating a bursty interfering wave is changed to ADSL down by changing the duration and repetition period under a constant duty ratio (0.125) condition. An experiment to apply to the communication signal was conducted.

  The experimental results are shown in FIG. As is clear from FIG. 1, it was confirmed that the lowering of the throughput was suppressed as the duration of the bursty interference wave was increased. This point will be described with reference to FIG. 2 showing the modulation interval of the ADSL frame and the application timing of the bursty interference wave. ADSL generates a transmission frame by QAM at a rate of once every 250 μs. The time divided by the modulation interval of the transmission frame is defined as a time slot, and the probability that an interference wave is applied in the time slot is represented by n (interrupted time slot) / N (all time slots). Referring to FIG. 2, when the interference probability n / N is set as Condition A: 5/6, Condition B: 5/8, Condition C: 1/2, Condition D: 1/4, a bursty interference wave (SW In a region where the repetition period of the pulse modulated wave (duty ratio 0.125) is longer than the ADSL time slot (250 μs), the interference probability of the time slot decreases as the duration (synonymous with the repetition period) becomes longer. In other words, the experimental result indicating that the throughput does not decrease as the duration time increases corresponds to the fact that the throughput is less likely to decrease as the interference probability of the time slot decreases.

  Therefore, in the embodiment of the present invention, in order to prevent a decrease in throughput due to interference with an ADSL transmission frame, it is determined in advance at what frequency and at what timing a bursty interference wave having the strength to interfere with the transmission frame is generated. 1 is detected, and a guaranteed throughput value as shown in Fig. 1 is determined in advance depending on the intended use, and a frame is transmitted at a time when the throughput exceeds the guaranteed value even in the presence of the disturbing wave. To do. By doing so, it is possible to perform information transmission without being affected by the interference wave.

  Specifically, prior to the transmission of digital information, the frequency component information and burstiness of the bursty interference wave having the strength to disturb the transmission frame with respect to the bursty interference wave existing on the communication transmission line connecting the transmitter and the receiver. The duration time information and the generation period information of the bursty interference wave that characterizes the periodicity of the interference wave are extracted and stored in the memory as interference wave parameters. At this time, the extracted interference wave parameter is stored in the memory in association with the throughput information in the presence of the interference wave. Information is transmitted during the time when there is no interfering wave, or when the interfering wave has a long duration, that is, when it is possible to secure a throughput that exceeds the guaranteed throughput value determined in advance by the intended use. I do. As a result, digital information can be transmitted while always ensuring a throughput equal to or greater than the guaranteed throughput.

[First Embodiment]
FIG. 3 shows a configuration example of the digital information transmission system according to the first embodiment of the present invention. The digital information transmission system shown in FIG. 3 includes a transmitter TX and a receiver RX that are connected to each other via a communication transmission line L2. The digital information transmission system basically transmits digital information between a transceiver (communication device). Here, a case where digital information is transmitted from one transmitter / receiver to the other transmitter / receiver will be described. A transmitter / receiver that plays a role of transmitting digital information is called a transmitter, and a transmitter / receiver that plays a role of receiving digital information. The machine is called a receiver. For this reason, the receiver RX can have the same hardware configuration and function as the transmitter TX. The hardware configuration of the transmitter TX illustrated in FIG. 3 is basically the same as the configuration adopted in the conventional transceiver for ADSL communication, but the information processing according to the present invention is shown in FIG. As described above, the hardware function may be performed by a DSP (Digital Signal Processor), and the software function may be performed by a CPU (Central Processing Unit).

  An electronic device (not shown) such as a PC or a server is connected to the transmitter TX via a LAN (Local Area Network) cable (Ethernet (registered trademark) cable in the example of FIG. 3) L1. The electronic device inputs digital information to be transmitted (Ethernet frame in the example of FIG. 3) to the transmitter TX. The transmitter TX transmits the input digital information to the receiver RX via the communication transmission path L2 by the multicarrier communication method. Specifically, the transmitter TX includes a LAN interface (LAN-IF) 31, a CPU 32, a memory 33, a DSP 34, an AFE 35, and an input / output interface (I / O-IF) 36.

  Digital information input from the electronic device is passed to the CPU 32 via the LAN interface 31. The CPU 32 executes software processing of a conventional ADSL information transmission function. This information transmission function includes a “training” process for calculating the link speed and the amount of data to be transmitted by one modulation using information obtained by exchanging signals between ADSL transceivers. The digital information is divided into a predetermined data length such as 48 bytes by software processing in the CPU 32, and additional information necessary for subsequent processing is added and stored in the memory 33. The DSP 34 reads the information divided from the memory 33 and performs a series of data processing including frame (output frame) generation generated by one modulation. In this process, as shown in FIG. 4, the DSP 34 performs CRC encoding (T1), RS encoding (T2), scramble processing (T3), trellis encoding (T4), QAM (T51), and IFFT (T52). ) Including DMT modulation (T5) and CP addition processing (T6). The AFE 35 executes AFE processing (T7). Specifically, the AFE 35 maps the digital signal generated by the DSP 34 to an analog signal, generates an analog transmission signal, and sends the analog transmission signal to the communication transmission path L2 via the input / output interface 36. The input / output interface 36 of the transmitter TX and the input / output interface of the receiver RX are connected by wire, and the section becomes the communication transmission path L2.

  The receiver RX receives an analog transmission signal from the transmitter TX, converts the received analog transmission signal into a digital signal, stores it in a memory, reads out the digital signal from the memory, and connects to the receiver RX or a PC or server Processing necessary for communicating with an electronic device via the LAN interface is performed via the DSP and CPU in the reverse order of the transmitter TX. Specifically, the receiver RX performs analog-digital conversion on the received analog transmission signal (R1), and performs waveform equalization processing (R2) on the time axis. Then, after deleting the CP from the digital signal (R3), first, DMT demodulation processing (R4) is performed for each subcarrier by FFT. Subsequently, the demodulated signal is subjected to waveform equalization processing (R5) on the frequency axis, and then subjected to QAM demodulation and processing (R6) for restoring the received baseband signal. Further, the received baseband signal obtained by the demodulation process is subjected to symbol determination of the received signal by the Viterbi decoder (R7), and then descrambled (R8) and RS decoded (R9). Then, the data after the error correction processing is inspected for an information error by CRC inspection (R10). The data after the CRC inspection is temporarily stored in a memory and then transferred from the LAN interface to an electronic device such as a PC or a server (not shown) via a LAN cable.

  Incidentally, the DSP 34 of the transmitter TX includes a digital information transmission processing unit 50 as a new function necessary for realizing the present embodiment in addition to the above basic function. The digital information transmission processing unit 50 includes an interference wave parameter extraction unit 52 and a frame transmission processing unit 53. The interference wave parameter extraction unit 52 detects an interference wave having an intensity that interferes with the transmission frame, and sets the duration and generation period of the interference wave as an interference wave parameter for each subcarrier used for information transmission to the receiver RX. Extract. The frame transmission processing unit 53 performs frame transmission processing based on the interference wave parameter for each subcarrier extracted by the interference wave parameter extraction unit 52.

  FIG. 5 is a block diagram showing a more detailed functional configuration of the digital information transmission processing unit 50. As shown in FIG. 5, the interference wave parameter extraction unit 52 includes an edge trigger unit 521, a measurement unit 522, and a statistical processing unit 523. The frame transmission processing unit 53 includes a frame transmission method determination unit 531, a frame transmission unit 532, and a frame reading unit 533. The storage unit 54 and the transmission / reception frame storage unit 55 shown in FIG. 5 can be realized by the memory 33 shown in FIG.

  Since the interference wave signal detected on the communication transmission line L2 is subjected to FFT processing by the FFT processing unit 51 and then passed to the interference wave parameter extraction unit 52, time-series data is accumulated for each subcarrier. In the present embodiment, a signal observed in a state where communication is not performed between the transceivers is assumed to be an interference wave signal. The time series data of the interference wave signal is illustrated in FIG. The interference wave parameter extraction unit 52 estimates the interference wave duration and generation period for each subcarrier. In a certain subcarrier, the edge trigger unit 521 of the jamming wave parameter extracting unit 52, when the strength of the jamming wave signal exceeds a threshold, that is, the strength of jamming the transmission frame, as shown by the broken circle in FIG. Detect when it falls below the threshold. The measuring unit 522 measures the time from when the threshold is exceeded to when the threshold is below the threshold, as the disturbance wave duration. The statistical processing unit 523 creates a histogram of the duration measured by the measurement unit 522, thereby determining the duration of the histogram as the maximum duration of the interference wave mixed in the communication transmission path in the future. Furthermore, the measurement unit 522 measures the time from when the intensity of the interference wave signal exceeds the threshold value until it once falls below the threshold value and exceeds the threshold value again as the generation period of the interference wave. The statistical processing unit 523 creates a histogram of the generation period measured by the measurement unit 522 in the same manner as the processing for the duration time, thereby causing the generation period that becomes the maximum value of the histogram to be mixed into the communication transmission path in the future. It is determined as the generation period. The jamming wave parameter extraction unit 52 performs processing on the duration and generation period of the jamming wave for each subcarrier after the FFT processing.

  The value of the interference wave parameter (duration and generation period) calculated for each subcarrier is stored and updated in the storage unit 54 in association with the throughput in the presence of the interference wave. For example, a database is constructed by experimentally obtaining the relationship between the interference wave parameters (duration and generation period) and the throughput, and the throughput can be reduced by referring to the database with the interference wave parameter calculated for each subcarrier. It is determined. By performing the interference wave parameter extraction process for each subcarrier, the interference wave signal strength is small and the threshold is not exceeded in subcarriers of frequency components in which no interference wave exists. Can be determined as 0 seconds, and a lot of digital information can be assigned to the subcarriers.

  The frame transmission method determination unit 531 determines a transmission method capable of securing a guaranteed throughput value based on a comparison between the throughput associated with the interference wave parameter stored in the storage unit 54 and the guaranteed throughput value. Specifically, the frame transmission method determination unit 531 does not transmit a frame at a time when there is an interfering wave that lowers the throughput. On the other hand, the throughput does not decrease even if the interfering wave exists, or a throughput guarantee value It is determined to transmit a frame at a time that can be secured.

  As an example, a method for realizing transmission with a guaranteed throughput value indicated by a solid line in FIG. 1 will be described below. When the length of data input from the lower part of the transmitter to the transmitter TX is L, and data that can be transmitted to the receiver RX side in one transmission frame is T, data having a length of L is transmitted from the transmitter TX to the receiver. A time slot N required for transmission to RX is represented by N = L / T. Assuming that D is the number of consecutive time slots in which an interference wave having an intensity that interferes with a transmission frame is present, when D = 0, the transmission frame is not disturbed, and transmission is performed as usual. In the plot of FIG. 1, increasing the value on the horizontal axis is synonymous with increasing D. Since the transition of the plot tends to monotonically increase, if the value of D when the solid line indicating the guaranteed value and the transition of the plot intersect is k, the normal transmission method is used in the range of 0 <D <k. Because the throughput is lower than the guaranteed value, information transmission is not performed in time slots where there are interference waves with the strength to disturb the transmission frame, but information transmission is performed only in time slots where there is no interference wave with the strength to interfere with the transmission frame. I do. At this time, the time N ′ required to complete the data transmission is in a relationship of N ′> N. However, even if the data is sent by N or the data sent by N ′, Since the receiver TX reads out an error-free frame from the memory at a constant speed v, in either case, the time required to complete the data transmission to the lower part of the receiver does not change with L / v, so the throughput is reduced. Avoided.

  On the other hand, in the range of k ≦ D, the throughput exceeds the guaranteed value in spite of the presence of the interference wave having the strength to disturb the transmission frame. In this case, the throughput has the strength to disturb the transmission frame. Information transmission is performed even in a time slot in which an interfering wave exists. Further, as described above, since information transmission is performed only in the time slot in which there is no interference wave having an intensity that interferes with the transmission frame, the information input to the transmitter TX is not yet sent to the receiver RX. No information, i.e., information that was scheduled to be transmitted at the time when the bursty jammer with a short duration exists, is transferred to the time slot of the time when the bursty jammer with a long duration exists, and is transmitted, Events in which the throughput falls below the guaranteed value due to the transmission frame being disturbed are avoided. Also in this case, since the receiver RX reads out an error-free frame from the memory at a constant speed v, the time required for completing the data transmission to the lower part of the receiver does not change with L / v, and a decrease in throughput is avoided. Is done.

  The frame transmission unit 532 transmits a transmission frame to the receiver RX via the communication transmission path L2 according to the transmission method determined by the frame transmission method determination unit 531. In the receiver RX, the frame transmitted from the transmitter TX is stored in the transmission / reception frame storage unit of the receiver RX, and the frame reading unit of the receiver RX reads the frame from the transmission / reception frame storage unit for normal frame transmission processing. Move processing.

  When frame transmission is performed by the above method, an event that does not transmit a frame occurs during the time when there is an interfering wave that lowers the throughput. However, since the transmission frame received by the receiver is temporarily stored in the transmission / reception frame storage unit, the speed at which the receiver reads the information of the transmission frame is constant. Furthermore, since the transmission frame read by the receiver can eliminate the influence of the interference wave in principle by transferring it to each transmission process via the input / output interface, normal transmission is possible. The restoration information after performing error correction processing according to the processing flow does not include an error, and is not discarded after CRC check in ADSL, and there is no need to perform retransmission processing.

Next, the operation of the digital information transmission system according to this embodiment will be described.
FIG. 7 is a sequence diagram illustrating an example of a frame transmission process between the transmitter TX and the receiver RX illustrated in FIG. The transmitter TX and the receiver RX are disturbing waves that exist on the communication transmission line L2 that connects the transmitter TX and the receiver RX in a state where communication between the transmitter TX and the receiver RX is not performed. Is detected (step S71). The interference wave parameter extraction unit 52 of the transmitter TX detects an interference wave having an intensity that interferes with the frame for each subcarrier (step S72), and estimates the duration and generation period of the interference wave for each subcarrier. Subsequently, the interference wave parameter extraction unit 52 stores the interference wave duration and generation period estimated for each subcarrier in the storage unit 54 in association with the throughput (step S73). Similarly to the transmitter TX, the receiver RX detects an interfering wave having an intensity for interfering with the frame for each subcarrier (step S75), estimates the duration and generation period of the interfering wave for each subcarrier, The interference wave duration and generation period estimated for each carrier are stored in the storage unit in association with the throughput (step S76).

  Next, the frame transmission method determination unit 531 of the transmitter TX refers to the information stored in the storage unit 54, and determines a frame transmission method for securing a guaranteed throughput value (step S74). The frame transmission unit 532 of the transmitter TX performs frame transmission according to the frame transmission method determined by the frame transmission method determination unit 531 (step S77).

  The receiver RX receives the frame from the transmitter TX and stores it in the transmission / reception frame storage unit (step S78). The frame reading unit of the receiver RX reads frames from the transmission / reception frame storage unit at a constant speed v (step S79). The receiver RX obtains digital information by performing predetermined processing on the read frame and passes it to an electronic device (not shown). As a result, transmission with L / v throughput always secured is possible at the lower part of the receiver.

  FIG. 8 is a flowchart showing an operation example of the digital information transmission processing unit 50 shown in FIG. In step S81 of FIG. 8, the edge trigger unit 521 detects when the intensity of the jamming wave signal exceeds the threshold and when the intensity of the jamming wave signal falls below the threshold in a certain subcarrier. In step S <b> 82, the measurement unit 522 measures the duration and generation period of the disturbing wave based on the detection result by the edge trigger unit 521. Specifically, the measurement unit 522 measures the time from when the intensity of the jamming wave signal exceeds the threshold to when it falls below the threshold as the duration of the jamming wave, and from when the intensity of the jamming wave signal exceeds the threshold. The time until the threshold value is once exceeded below the threshold value is measured as an interference wave generation period. The processes of steps S81 and S82 are executed, for example, over a predetermined time interval, whereby a plurality of disturbance wave durations and generation periods are acquired.

  In step S83, the statistical processing unit 523 calculates the duration and generation period of the interference wave mixed in the communication transmission line based on the measurement result by the measurement unit 522, and uses this as the interference wave parameter of the subcarrier. And Specifically, the statistical processing unit 523 creates a histogram for each of the duration and occurrence period measured by the measurement unit 522 and mixes the duration and occurrence period that are the maximum values of the histogram into the communication transmission line in the future. Determined as the duration and generation period of the jamming wave.

  The processing shown in steps S81 to S83 is executed for each subcarrier used for communication with the receiver RX, whereby the interference wave parameter is calculated for each subcarrier. In step S84, each interference wave parameter is stored and updated in the storage unit 54 in association with the throughput of the interference wave parameter in the presence of the interference wave.

  In step S85, the frame transmission method determination unit 531 refers to the throughput information associated with the jamming parameter stored in the storage unit 54, and determines a transmission method that can secure a guaranteed throughput value. For example, the frame transmission method determination unit 531 transmits the subcarriers whose throughput exceeds the guaranteed value at a time when there is no interfering wave, and the subcarriers whose throughput is lower than the guaranteed value for the time when the interfering wave exists and The transmission method is determined so that transmission is performed in both times when there is no jamming wave. In step S86, the frame transmission unit 532 transmits the frame to the receiver side according to the transmission method determined by the frame transmission method determination unit 531. The interference wave parameter extraction unit 52 stores the interference wave parameters (duration and generation period) for each subcarrier in the storage unit 54 without performing association with the throughput, and the frame transmission method determination unit 531 You may make it obtain the throughput according to the interference wave parameter stored in the memory | storage part 54 with reference to a database.

  Through the above-described series of processing, information transmission is performed while avoiding subcarrier interference caused by jamming waves as much as possible, and even in the presence of jamming signals, information transmission at a throughput exceeding the guaranteed throughput value and minimization of error occurrence probability Is possible.

  As described above, in the first embodiment, in the transmitter, for each subcarrier, the duration and generation period of electromagnetic interference having an intensity exceeding the threshold value are estimated, and according to the estimated duration and generation period. The transmission method is determined based on the comparison between the throughput and the guaranteed value, and signal transmission is performed according to the determined transmission method. Thereby, it becomes possible to transmit digital information while avoiding the influence of the interference wave. As a result, high-throughput information transmission can be performed even in an environment where interference waves exist.

[Other Embodiments]
In the first embodiment, the case where the present invention is applied to an ADSL transmission / reception system has been described. However, the configuration of the present invention can be applied to an Ethernet transmission system that transmits digital information as a time-series electrical signal, or an OFDM (multi-carrier transmission scheme OFDM ( The present invention can also be applied to various digital information transmission systems including a wireless digital information transmission system adopting an orthogonal frequency division multiplexing (orthogonal frequency division multiplexing) modulation method. Further, the present invention can be applied not only to a multicarrier communication system but also to a single carrier communication system. Further, the connection between the transceivers is not limited to a wired connection, and may be a wireless connection. Furthermore, for the threshold value for disturbing the transmission frame shown in the first embodiment, the threshold value can be determined in consideration of error correction processing adopted in the digital information transmission system to be used.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in each embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  TX ... Transmitter, RX ... Receiver, L1 ... LAN cable, L2 ... Communication transmission path, 31 ... LAN interface, 32 ... CPU, 33 ... Memory, 34 ... DSP, 35 ... AFE, 36 ... I / O interface, 50 ... Digital information transmission processing unit 51 ... FFT processing unit 52 ... Interference wave parameter extraction unit 53 ... Frame transmission processing unit 54 ... Storage unit 55 ... Transmission / reception frame storage unit 521 ... Edge trigger unit 522 ... Measurement unit 523: Statistical processing unit, 531: Frame transmission method determining unit, 532: Frame transmission unit, 533: Frame reading unit.

Claims (6)

A digital information transmission system for transmitting digital information from a transmitter to a receiver using at least one carrier frequency,
The transmitter is
Estimating means for estimating the duration and generation period of electromagnetic interference having an intensity exceeding a threshold for each carrier frequency;
Determining means for determining a transmission method for each carrier frequency based on a comparison between a throughput and a guaranteed value according to the estimated duration and generation period;
Transmitting means for transmitting according to the determined transmission method;
A digital information transmission system comprising:   The determination means transmits the carrier frequency for which the throughput exceeds the guaranteed value at a time when the electromagnetic interference does not exist, and exists for the carrier frequency whose throughput is less than the guaranteed value. 2. The digital information transmission system according to claim 1, wherein the transmission method is determined so that transmission is performed both at a time when the electromagnetic interference wave is present and when the electromagnetic interference wave is not present. A digital information transmission method for transmitting digital information from a transmitter to a receiver using at least one carrier frequency, comprising:
The transmitter estimates, for each carrier frequency, a duration and generation period of an electromagnetic interference having an intensity exceeding a threshold;
The transmitter determines a transmission method for each carrier frequency based on a comparison between a throughput and a guaranteed value according to the estimated duration and generation period;
The transmitter performs transmission according to the determined transmission method;
A digital information transmission method comprising:   The transmission method is determined by transmitting the carrier frequency for which the throughput exceeds the guaranteed value at a time when the electromagnetic interference does not exist, and for the carrier frequency for which the throughput is less than the guaranteed value. 4. The digital information transmission method according to claim 3, further comprising: determining the transmission method so that transmission is performed both in a time in which an interference wave exists and in a time in which the electromagnetic interference wave does not exist. A transmitter for transmitting digital information to a receiver using at least one carrier frequency,
Estimating means for estimating the duration and generation period of electromagnetic interference having an intensity exceeding a threshold for each carrier frequency;
Determining means for determining a transmission method for each carrier frequency based on a comparison between a throughput and a guaranteed value according to the estimated duration and generation period;
Transmitting means for transmitting according to the determined transmission method;
A transmitter comprising:   The determination means transmits the carrier frequency for which the throughput exceeds the guaranteed value at a time when the electromagnetic interference does not exist, and exists for the carrier frequency whose throughput is less than the guaranteed value. The transmitter according to claim 5, wherein the transmission method is determined so that transmission is performed both at a time when the electromagnetic interference wave is present and when the electromagnetic interference wave is not present.