JPH02215236A - Data transmitter - Google Patents

Abstract

PURPOSE:To decrease a transmission error by generating a trellis diagram corresponding to a transmission signal by impulse response of a reception signal, calculating an error corresponding to an input pattern, confirming a path in the trellis diagram and decoding the received data. CONSTITUTION:A line estimate device 7 estimates an impulse response of a transmission line of a radio line from a modulation signal of a base band, and a matching filter 8 uses the impulse response to improve the S/N of a modulation signal of a base band. Then a branchmetric arithmetic computing element 9 uses the impulse response estimated by the estimate device 7 to predict an output signal of the filter 8 corresponding to all patterns of the transmission signal, calculates a square error between all the predicted values and the actual output of the filter 8 and outputs a branchmetric representing an error at a sample point of an output signal of the filter 8. Then an ACS computing element 10 obtains a pathmetric being a candidate of paths up to time (n+1) in the trellis diagram.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data transmission device used in digital mobile communications and the like.

Conventional technology FIG. 2 shows the configuration of a conventional data transmission device.

On the left side of FIG. 2, 21 is a modulator that modulates transmission data, and 22 is an amplifier that amplifies the signal modulated by the modulator 21 and transmits it as a radio wave via the antenna 23. Members 21 to 23 constitute a transmitter.

On the right side of FIG. 2, 25 is an amplifier that amplifies the signal received via the antenna 24, 26 is a detector that converts the received signal amplified by the amplifier 25 into a baseband modulation signal, and 27 is: This is a discriminator that identifies the modulated signal detected by the detector 26 based on the time when the eye is most open, and outputs decoded data.

In the above configuration, the discriminator 27 on the receiving side identifies the modulated signal detected by the detector 26 at the time when the eye is the most open, so that when a signal without distortion is received, the received data can be decoded without error. be able to.

Problems to be Solved by the Invention However, in the conventional data transmission device described above, since interference between codes generally occurs due to the influence of delayed waves in the transmission path of a wireless line, the received signal is It is possible that there is no distortion, so there is a problem that data cannot be accurately transmitted over the wireless link.

In view of the above-mentioned conventional problems, the present invention provides a data transmission device that can reduce transmission errors due to the influence of delayed waves occurring in a radio channel transmission path, and can obtain the likelihood of decoded data. The purpose is to

Means for Solving the Problems In order to achieve the above object, the present invention includes a detector that converts a received signal from a transmitting section into a baseband signal, and an impulse response of a radio line transmission path using this baseband signal. A line estimator that uses this impulse response to improve the S/N ratio of the baseband signal and outputs it, and a matched filter that uses the impulse response to predict the output signal of the matched filter that corresponds to all patterns of the transmitted signal. A branch metric calculator that calculates a branch metric that indicates the error between the predicted value and the output signal of the matched filter, and adds this branch metric according to the trellis diagram to select an expected path and calculate the selected path. information indicating a branch to determine, an ACS calculator that calculates a branch metric corresponding to the branch, a path metric that represents the likelihood of the path, and a storage that saves this bus metric for the next calculation by the ACS calculator. The state representing the received signal is determined using the information indicating the branch that determines the path, and the received data is decoded using that state, and the likelihood is assigned to each bit of the decoded data using the branch metric that leads to that state. The receiver is equipped with a trellis decoder that is additionally output.

According to the above configuration, the present invention uses the impulse response of the received signal to construct a trellis diagram corresponding to the transmitted signal, calculates errors corresponding to all input patterns, determines the path of the trellis diagram, and receives the signal. Since the data is decoded, transmission errors due to the influence of delayed waves occurring in the radio channel transmission path can be reduced, and the likelihood of decoded data can be obtained.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention.

On the left side of FIG. 1, 1 is a modulator that modulates transmission data, and 2 is an amplifier that amplifies the signal modulated by the modulator 1 and transmits it as a radio wave via the antenna 3. Members 1 to 3 constitute a transmitter.

On the right side of FIG. 1, 5 is an amplifier that amplifies the signal received via the antenna 4, and 6 is a detector that converts the received signal amplified by the amplifier 5 into a baseband modulated signal.

Further, 7 is a line estimator that estimates the impulse response of the transmission path of the wireless line using the baseband modulated signal converted by the wave detector 6; A matched filter that improves the S/N ratio of the baseband modulated signal converted by the detector 6 and outputs it; 9 is a matched filter that improves the S/N ratio of the baseband modulated signal converted by the wave detector 6; 9 is a matched filter that improves the S/N ratio of the baseband modulated signal converted by the wave detector 6; This is a branch metric calculator that predicts the output signal of the matched filter 8 corresponding to all the patterns of and calculates the error (branch metric) between this predicted value and the signal actually output from the matched filter 8.

10 selects an assumed path by adding the branch metric calculated by the branch metric calculator 9 according to the trellis diagram, and information indicating a branch that determines the selected path and information corresponding to the branch. An ACS calculator 11 outputs a branch metric and a likelihood (path metric) indicating the certainty of a path.
Save the path metric from 0 and use A for next calculation
a path metric storage device 12 that outputs to the CS calculator 10;
determines the state representing the received signal using the information indicating the branch that determines the path from the AC3 arithmetic unit 10, decodes the received data using that state, and decodes each bit of the received data using the branch metric leading to that state. This is a trellis decoder that adds likelihood, and the above members 4 to 12 constitute a receiving section.

Next, the operation of the above embodiment will be explained.

In FIG. 1, the baseband signal modulated and transmitted by the transmitter and received and detected by the receiver is as follows:
It includes transmission errors due to the influence of delayed waves that occur in the wireless transmission path.

Therefore, the line estimator 7 estimates the impulse response of the wireless line transmission path from the baseband modulated signal,
The matched filter 8 uses this impulse response to improve the S/N ratio of the baseband modulation signal.

Next, the branch metric calculator 9 uses the line estimator 7
Using the estimated impulse response, predict the output signals of the matched filter 8 corresponding to all patterns of the transmitted signal, calculate the squared error between all the predicted values and the actual output value of the matched filter 8, A branch metric link representing the error at the sample point of the output signal of the matched filter 8 is output.

In this case, the branch metric calculator 9 first calculates the time "
Assuming a trellis diagram corresponding to a modulated signal from "0", for the possible paths up to time n in the trellis diagram,
Then, the ACS calculator 10 outputs the branch metric obtained from the sample value at time n+1. Then, the ACS calculator 10 calculates the sum of the branch metrics (path metric) corresponding to the path up to time n calculated by the branch metric calculator 9. time n+1
By adding the branch metrics at , the path metric of the path candidate at time n+14 in the trellis diagram is determined.

Here, since a plurality of paths are assumed for each state at time n+1, the most probable path is selected for each state by comparing path metric links. still,
At this time, the path metric of the selected path is stored in the storage 11.
It is used for calculation at time n+2 by outputting it to
The trellis decoder 12 also sends information indicating the branch that determines the selected path, the branch metric corresponding to the branch, and the likelihood (path metric) indicating the probability of the path.
Output to.

The trellis decoder 12 determines the path of the trellis diagram at each time using information indicating which path has been selected, and in this case, each state on the determined path corresponds to a predicted value of the received signal. The received data is decoded based on that state, and then the branch metric leading to that state is normalized by the sum of squares of the impulse response of the transmission path and output as the likelihood of the received data.

Therefore, according to the above embodiment, a trellis diagram corresponding to the transmitted signal is constructed using the impulse response of the received signal, errors corresponding to all input patterns are calculated, and the paths of the trellis diagram are determined. Since the received data is decoded, transmission errors due to the influence of delayed waves occurring in the radio channel transmission path can be reduced, and the likelihood of the decoded data can be obtained.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention uses an impulse response of a received signal to construct a trellis diagram corresponding to a transmitted signal;
Since the error corresponding to all input patterns is calculated and the path of the trellis diagram is determined to decode the received data, it is possible to reduce transmission errors due to the influence of delayed waves that occur in the wireless transmission path. It is also possible to obtain the likelihood of decoded data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention, and FIG. 2 is a block diagram showing a conventional data transmission device. 1... Modulator, 2.5... Amplifier, 3, 4... Antenna, 6... Detector, 7... Line estimator, 8...
・Matched filter, 9 ・Branch metric calculator, 1
0...ACS computing unit, 11...Path metric storage device, 12...Trellis decoder. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] a transmitter that modulates and wirelessly transmits transmission data; a detector that converts the received signal from the transmitter into a baseband signal; and a baseband signal from the detector that detects the impulse response of the transmission path of the wireless line. a line estimator for estimating;
S/ of the baseband signal is determined by the impulse response.
A matched filter that outputs an improved N ratio, and an output signal of the matched filter that corresponds to all patterns of the transmitted signal based on the impulse response, and an error between this predicted value and the output signal of the matched filter is shown. A branch metric calculator that calculates a branch metric, and information indicating a branch that selects an assumed path by adding the branch metric according to the trellis diagram and determines the selected path, and information corresponding to the branch. AC that calculates the branch metric and path metric that indicates the likelihood of the path.
A state representing the received signal is determined by an S calculation unit, a storage unit that stores the path metric for the next calculation by the ACS calculation unit, and information indicating a branch that determines the path, and the reception signal is determined according to the state. 1. A data transmission device comprising: a receiving section that includes a trellis decoder that decodes data and adds a likelihood to each bit of the decoded data using a branch metric to reach the state.