KR100450772B1 - Apparatus for receiving data in Home Network modem and method thereof - Google Patents

Abstract

The present invention relates to a modem for digital data communication, and more particularly, to a receiver and a receiving method of a modem applied when a home network is formed using a telephone line for high-speed data communication. A frame restoring unit for restoring a signal; After receiving the input signal and storing the input signal and a selection signal for designating a mode for determining whether there is a collision on a transmission line, and if the selection signal is in the collision detection mode, the stored input signal is transmitted by a frame synchronization signal. A selector for outputting the signal by bypassing the input signal in a normal reception mode; And an equalization unit configured to equalize the output signal of the selection unit by adjusting the number of equalization taps based on the selection signal, so that the equalizer can equalize the channel using all of the training signal sequences from the beginning. The performance was improved, and the EOF detection performance was enhanced by checking the correlation between the equalized signal through the equalizer and the phase compensator during EOF detection. Also, in the collision detection mode in which the data transmitted by the user is to be received, unlike the normal reception mode, the collision detection mode is reduced by reducing the demodulation delay to increase the accuracy of collision detection.

Description

Apparatus for receiving data in Home Network modem and method

The present invention relates to a modem for digital data communication, and more particularly, to a receiver and a reception method of a modem applied when a home network is configured using a telephone line for high speed data communication.

A technology using a telephone line (US Pat. No. 6,026,150) is being used as a way to network computers and equipment related to homes as well as electronic products. In this technology, each entity connected to the network sends and receives signals to and from the telephone line with a modem inside. Each entity on the network transmits data frame by frame and the entity corresponding to the destination of the frame restores it. The schematic configuration of the modem receiver, which plays the above role, shows the non-idle detector that checks the state of the telephone line, the echo canceler that removes its own signal included in the received signal, and the symbol synchronization. It consists of a sampler, an equalizer for compensating for channels, a carrier recovery for compensating for carrier phase errors, and a decoder for recovering symbols with constellations.

In the conventional home network telephone line modem, the burst mode transmits frame by frame only when transmission is desired, and the equalizer operates in a training mode by using the preamble included in each frame to equalize the transmission channel. Since a limited preamble is used, the modem receiver must be designed to take full advantage of it. In addition, the telephone line modem compares the transmitted frame by the collision detection method between different frames and compares it with the frame transmitted by the receiver of the modem. In this process, when the signal demodulation time of the modem receiver is excessively elapsed, there is a problem that the time to start the comparison is late and the data cannot be compared.

An object of the present invention is to provide a receiver and a method for reducing a demodulation delay in a collision detection process by separating an operation at a collision detection and an operation at a normal reception in a telephone line modem for a home network. .

1 is a diagram illustrating a data frame structure transmitted and received by a modem for a home network using a telephone line.

2 is a functional block of a receiving apparatus of a modem for a home network according to the present invention.

3 is an overall functional block of a modem to which a reception apparatus of a modem for a home network according to the present invention is applied.

4 is a detailed functional block of the equalizer of FIG. 2.

5 is a flowchart illustrating a method of receiving a modem for a home network according to the present invention.

In order to achieve the above technical problem, a modem receiving apparatus according to the present invention includes a frame restoring unit for recovering a frame synchronization signal from an input signal; After receiving the input signal and storing the input signal and a selection signal for designating a mode for determining whether there is a collision on a transmission line, and if the selection signal is in the collision detection mode, the stored input signal is transmitted by a frame synchronization signal. A selector for outputting the signal by bypassing the input signal in a normal reception mode; And an equalization unit configured to equalize the output signal of the selection unit by adjusting the number of equalization taps based on the selection signal.

In order to achieve the above technical problem, a modem reception method according to the present invention includes determining whether or not to determine whether a collision on a transmission line; Restoring a frame synchronization signal from the input signal; Storing the input signal when the collision determination step determines normal reception, and bypassing the input signal when determining collision detection; And adjusting the number of taps of the equalizer based on the determination of the collision determination step.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Looking at the structure of the first transmitted frame has a configuration as shown in FIG. The frame is largely divided into a header 110 and data 130 and an end of frame (EOF) 150 indicating the end of one frame, and the header is further divided into a preamble 111 and a control signal 113. Referring to FIG. 1, there is a preamble that repeats the promised pattern TRN16 four times. The equalizer 230 operates in a training mode using the promised pattern of the preamble to equalize the channel. In FIG. 1, the header 110 and the EOF 150 are transmitted at a basic transmission rate QPSK, and the data region 130 can be up to 256 QAM in QPSK according to channel conditions.

The receiver of the telephone line modem according to the present invention will be described with reference to FIG. The modem not only receives a frame being transmitted on a transmission line but also receives and recovers a frame sent by its transmitter. The reason for receiving the frame sent by the user is to recover the frame and determine that the transmission line is empty when the data is normal, and continue to send the data. This comparison is determined by comparing the header region 110 located at the front of the frame, and this determination is made until the data 130 is connected behind the header region. However, if there is a lot of delay in receiving and recovering a signal from the modem, the time to start the comparison is delayed. Therefore, if the modem reduces the delay in recovering the signal while receiving the input signal, it starts to compare the frame sent by itself with the received frame and compares a lot of header data. It becomes possible. The data area can be changed up to 256QAM depending on the state, but since the header area is transmitted to QPSK, the modem only needs to recover QPSK when recovering the header area by receiving its own frame. Therefore, it is not necessary to use all the demodulation functions of the modem, and by designing blocks that pass the shortened path to the modem receiver, it is configured to reduce the total pass delay by this time to increase the effect of collision detection. The present invention aims to reduce the passing delay by having a mode including a simple path to the frame synchronization recovery unit and the equalizer. In this case, when receiving the frame sent by the other party, all functions are performed, and this is the normal reception mode, and when the frame sent by the other party is directly received, it passes through the brief path and defines it as the collision detection mode.

In order to operate in two modes as described above, as shown in FIG. In general, the functional block required for recovering the input signal will be described with reference to FIG. 3 including the receiving apparatus of the present invention. The signal input to the modem is connected to the frame synchronization extractor 210 and the demultiplexer 221. Data is stored in the storage unit 223 in the normal reception mode and does not go through the storage unit 223 in the collision detection mode. The storage unit 223 may be configured with various storage means, for example, RAM. The frame synchronization extracting unit 210 is a block for extracting a frame synchronization signal from an input signal. The frame synchronization extracting unit 210 detects a sign of an input signal sequence and sends it to a correlator for obtaining a correlation between the input signal sequence and TRN16, which is a training signal. After the correlation is calculated for each symbol, the frame synchronization signal is output when the correlation is greater than the threshold value. The frame synchronization signal enables the output of the storage unit 223 in the normal reception mode to output the data stored in the storage unit 223, and does not go through the storage unit 223 in the collision detection mode, thereby preventing the frame synchronization recovery unit ( The data input to 200 is immediately output. The selection signal is a signal generated by the modem itself and selects the number of taps of the demultiplexer 221, the multiplexer 225, and the equalizer 230. That is, when the selection signal value is designated as the collision detection mode, the demultiplexer 221 and the multiplexer 225 output an input signal not passed through the storage unit 223 to the equalizer 230, and Only the first equalization block 401 is activated.

The phase correlator in the frame synchronization extracting unit 210 obtains a correlation with the signal input with the TRN16 signal sequence 111 and thus obtains up to four peak values. The storage unit 223 stores data for as many symbols as TRN16. Therefore, when the first peak value of the correlation calculated by the phase correlator exceeds the threshold value, the data corresponding to the first TRN16 is stored in the storage unit 223. Therefore, the first symbol can be exported in order without losing the preamble. Thus, in the normal reception mode, since the first symbol of the preamble is output, the training mode equalization time of the equalizer 230 connected to the rear can be sufficiently used to increase the performance of the equalization and the storage unit 223 does not go through the collision detection mode. It can't send as many preambles as TRN16, but it will reduce the delay.

The equalizer 230 will be described. 4 shows a more detailed functional block of the equalizer 230 operating in the above two modes. As shown in FIG. 4, the equalizer 230 is composed of four 4-tap blocks 401, 403, 404, and 405, and thus is composed of 16 taps. The 4-tap block is a block used to reduce hardware by dividing one multiplier necessary for calculating one tap in time and using four taps. In FIG. 4, the output of the 4-tap block is a result of multiply and add corresponding to the delayed signal and the 4-tap for the next block. The results of the four-tap blocks A, B, C, and D are combined to form the output of the forward equalizer. In the collision detection mode, 0 is input to the 4-tap block B. Therefore, the output of the 4-tap blocks B, C, and D connected to the rear end becomes 0, so the equalizer uses only 4-tap block A, which is equivalent to using a 4-tap equalizer. In collision detection mode, the channel is less affected because it receives its own signal. As a result of the experimental observation, it is possible to receive about QPSK when coefficients converge even using 4 taps, so only one 4 tap block is used. In other words, the performance of the equalizer is degraded, but the output starts faster. At this time, the input of the reverse equalizer 319 is also 0, and the reverse equalizer is not operated.

Now, a function block and a reception method of a modem including a reception device according to the present invention will be described with reference to FIGS. 3 and 5. The telephone line modem first converts an analog signal into a digital signal (310). The signal detection unit 311 determines the presence of a signal on the transmission line to activate or deactivate the operation of the modem itself. The automatic gain controller 312 measures the size of the input signal and adjusts it to an appropriate size (step 501). The gain-adjusted signal includes a notch filter 313 for removing interference of the HAM signal, a carrier multiplier for removing carrier components and dividing them by I and Q components, a matching filter 314 which is a low pass filter, and an optimal symbol. The frame synchronization recovery unit 200 is input to the frame synchronization recovery unit 200 via a symbol synchronization recovery unit 315 for finding timing. The frame synchronization recovery unit 200 has been described above. The symbol synchronization recovery unit 315 obtains an appropriate symbol synchronization from the input signal oversampled by the analog / digital conversion unit 310, and downsamples the symbol at a symbol rate to output the result. In this case, the frame synchronization restoring unit 200 operates according to the determination of whether to operate in the collision detection mode or the normal reception mode as described above, and the equalization unit also selects an operation method according to the determination (step 503). ). The signal passing through the frame synchronization restore unit 200 passes through the forward equalizer 230 and the reverse equalizer 319 to minimize the influence of channel passing. The signal that has passed through the symbol synchronization recovery unit 315 finds the start point of the frame in the frame synchronization extractor 210. Since the preamble at the beginning of the frame repeats the promised pattern TRN16 four times, it checks the similarity between the input signal and TRN16 and notifies the start of the frame when the predetermined threshold is exceeded (step 505). The frame start signal and data are input to the equalizer 230 to equalize the channel. The equalization function is composed of a forward equalizer 230 and a reverse equalizer 319 to perform a decision feedback equalization function and operate in a training mode in a preamble section to quickly equalize channels. When the frame synchronization recovery unit 200 stores data in the storage unit 223 and detects the start of a frame, the frame synchronization recovery unit 200 sends the data to the equalizer 230 so that the channel can be equalized by using all of the preambles from the beginning of the preamble. Increase performance (step 507). The phase compensator 318 compensates for the phase error of the signal passed through the forward equalizer 230. The signal compensated up to the phase finds a mapping value of the constellation in the signal determiner 320. This value is connected to the decoder 321 and converted into a bit string. This bit string is transferred to a general data processing device (eg, a CPU) according to the result of the EOF detector 323. The signal determiner 320 and the decoder 321 should operate from QPSK to 256QAM according to the data rate. The EOF detector 323 detects the end of frame (EOF) included in the end of the frame and uses the channel equalized signal to find the correlation with the EOF. When the EOF detector exceeds the predetermined threshold, the end of frame is transmitted to the data processing apparatus. Stop. Since the EOF detector 322 detects the EOF, since the EOF signal is shorter than the preamble, the detection of the EOF signal in the same part as the frame synchronization restorer 200 increases the probability of false positives. The EOF detection performance is increased by checking the similarity with the equalized signal having passed (318). The reason for the improvement in performance is as follows. The EOF detection may be performed at the same part as the frame synchronization restorer 200, but since the frame synchronization restorer 200 is located at the front end of the equalizer 230, the input signal includes distortion of the channel. By the way, the frame synchronization restoration unit 200 comparing TRN16 passes 16 symbols through the phase compensator 318, but only 4 symbols pass through the phase compensator 318, so that the error is much affected. Therefore, when EOF is detected with a signal that has undergone equalization and phase compensation, the performance is improved because the correlation with the correct symbol having the distortion compensated is obtained.

The modem receiving method according to the present invention can also be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and also carrier wave (e.g. transmission over the Internet). It is also included to be implemented in the form of. The computer readable recording medium can also be distributed over computer systems connected over a computer network so that the computer readable code is stored and executed in a distributed fashion. Also, the font ROM data structure according to the present invention can be read by a computer on a recording medium such as a computer readable ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage device, and the like. It can be implemented as code.

According to the present invention, when the receiver of the telephone line modem for the home network is configured, the equalizer can equalize the channel using all of the training signal sequences from the beginning, thereby improving the channel equalization performance. EOF detection performance is improved by checking correlation with coarse equalized signal. Also, in the collision detection mode in which the data transmitted by the user is to be received, unlike the normal reception mode, the collision detection mode is reduced by reducing the demodulation delay to increase the accuracy of collision detection.

Claims (8)

In a modem connecting to a home network, A frame restoring unit for restoring a frame synchronization signal from the input signal; After receiving the input signal and storing the input signal and a selection signal for designating a mode for determining whether there is a collision on a transmission line, and if the selection signal is in the collision detection mode, the stored input signal is transmitted by a frame synchronization signal. A selector for outputting the signal by bypassing the input signal in a normal reception mode; And And an equalization unit configured to equalize the output signal of the selection unit by adjusting the number of equalization taps based on the selection signal. The method of claim 1, wherein the selection unit A storage unit for storing the input signal and being activated by the frame synchronization signal to output the input signal; A first demultiplexer for outputting the input signal to the storage when the selection signal is in a normal reception mode and bypassing the input signal when in the collision detection mode; And a first multiplexer configured to output the bypassed input signal when the selection signal is the collision detection mode and output an output signal of the storage unit when the selection signal is the normal reception mode. The method of claim 1, wherein the equalizing unit And a second demultiplexer configured to have equal multiples of equalized blocks having integer multiples of taps, and to determine whether to output an output of the first equalized block among the equalized blocks to a second equalized block according to the selection signal. Modem receiving device characterized in that. The method of claim 1, wherein the modem And an end signal detector for detecting whether the input signal is terminated by detecting a frame end signal from the output signal of the equalizer. In a modem connecting to a home network, (a) determining whether to determine whether there is a collision on a transmission line; (b) restoring the frame synchronization signal from the input signal; (c) storing the input signal when determining the normal reception in step (a) and bypassing the input signal when determining the collision detection; (d) adjusting the number of taps of the equalizer based on the determination of step (a). The method of claim 5, wherein step (c) (c1) determining whether to output the stored input signal as the frame synchronization signal. The method of claim 5, wherein step (d) And determining the collision detection in the step (a), disconnecting the connection between the first and second equalization blocks of the integer multiples of the integer multiples having the connected integer multiples of the taps. . A computer-readable recording medium having recorded thereon a program for executing the steps of claim 5 on a computer.