JP2001144663A - Time diversity circuit using partial retransmission data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a time diversity circuit using partial retransmission data whose error correction capability is enhanced. SOLUTION: A transmitter side consists of a microphone 1a, a voice coding circuit 2a, a wireless packet division circuit 3a that divides data into wireless packets, a memory 4a, an error check coding circuit 5a that adds an error check code to the packets, an error correction coding circuit 6a that adds an error correction code to the packets, a modulator 7a, a transmitter 8a and a transmission antenna 9a. A receiver side consists of a reception antenna 10a, a receiver 11a, a demodulator 12a, an error correction coding circuit 13a that conducts decoding by using the error correction code, an error check coding circuit 14a that conducts error check, a wireless packet synthesis circuit 15a that generates a user packet, a memory 16a, a voice decoding circuit 17a, a speaker 18a, a retransmission control circuit 19a that generates a retransmission request packet, a data synthesis circuit 20a that generates a differential code and a memory 21a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time diversity circuit using partial retransmission data, and more particularly to a time diversity circuit using partial retransmission data with improved reception characteristics in a digital mobile communication system using partial retransmission control and an error correction code. Circuit.

[0002]

2. Description of the Related Art In a mobile communication system, the propagation of radio waves is generally multipath, and the mobile station is subject to fading in which the electric field strength level extremely increases and decreases as the mobile station runs. The sharp drop in the reception level due to the fading and the distortion of the waveform cause the deterioration of the error rate and hinder high-quality communication. Particularly, in a digital mobile communication system, a one-bit error due to the increase in the error rate becomes an error in the entire block including the erroneous data, leading to a deterioration in data transmission efficiency, which is a serious problem. In order to improve this fading, a plurality of paths in which the fading is statistically independent are provided, and a diversity technique for synthesizing signals passing through these paths or an error for correcting or detecting an error by adding redundancy to the data. Various techniques, such as the use of control codes and an automatic retransmission request method for transmitting data a plurality of times when an error is detected, have been put to practical use and implemented in a system.

FIG. 4 shows an example of a configuration of a conventional digital mobile communication system, in which (a) shows a base station apparatus,
(B) shows the opposing mobile station apparatus. In addition, in the reference numerals in FIG. 4, a is attached to the base station device side and b is attached to the mobile station device side. The transmitting side of both the base station apparatus and the mobile station apparatus is the microphone 1
a, 1b, and a speech encoding circuit 2 for digitizing speech
a, 2b, radio packet division circuits 3a, 3b for dividing into radio packets, memories 4a, 4b, error detection coding circuits 5a, 5b for adding error detection codes, and error correction codes for adding error correction codes Circuits 6a and 6b, modulators 7a and 7b, transmitters 8a and 8b, and transmission antenna 9
a and 9b. On the other hand, the receiving side performs error detection with the receiving antennas 10a and 10b, the receivers 11a and 11b, the demodulators 12a and 12b, the error correction coding circuits 13a and 13b that perform decoding using the error correction code. Error detection coding circuits 14a and 14b, radio packet combining circuits 15a and 15b for creating user packets,
Memories 16a, 16b, audio decoding circuits 17a, 17b for converting to analog signals, and speakers 18a, 18b
A retransmission control circuit 19a for creating a retransmission request packet,
19b.

The operation of FIG. 4 will be described with reference to the operation when digital data is transmitted from a base station apparatus to a mobile station apparatus. An analog signal such as voice is converted into an electric signal by a microphone 1a on the transmitting side of the base station apparatus. After that, the data is converted into digital data by the voice coding circuit 2a. The converted digital data is transmitted to the wireless packet division circuit 3a.
, The data is divided into wireless packets, which are transmission data units for each transmission, and are stored in the temporary memory 4a. When the transmission timing comes, the wireless packet division circuit 3a extracts the data for one transmission from the memory 4a, adds a header necessary for synthesizing the packet to the data, and adds an error detection code by the error detection encoding circuit 5a. Further, an error correction code is added by an error correction encoding circuit 6a, modulation is performed by a modulator 7a, and a desired frequency is converted by a transmitter 8a, and then output from an antenna 9a.

[0005] The signal output from the antenna 9a propagates in free space and is input from the antenna 10b of the opposing mobile station device, and is converted into a desired frequency by the receiver 11b.
The demodulator 12b demodulates the analog signal into a digital signal. Thereafter, decoding using the error correction code is performed in the error correction coding circuit 13b, and an error is detected using the error detection code in the error detection coding circuit 14b. If no error is detected here, the received data is sent to the wireless packet combining circuit 15b and temporarily transferred to the memory 16b. Then, in the wireless packet combining circuit 15b,
The header of the wireless packet is monitored, and the process of temporarily transferring the received data to the memory 16b until the last wireless packet arrives is repeated. If all the wireless packet headers for packet combining are completed, the wireless packet combining circuit 1
5b synthesizes the data according to the header and creates a user packet. This user packet is input to the audio decoding circuit 17b, converted into an analog signal in the audio decoding circuit 17b, and output via the speaker 18b.

If an error is detected in the data by the error detection coding circuit 14b using the error detection code, it is detected that all the headers are not aligned in the wireless packet combining circuit 15b, and the wireless packet that has not arrived has arrived. It prepares from the order of the wireless packet header, and prepares to send a retransmission request packet to the transmitting side for retransmission. For this reason,
The retransmission control circuit 19b creates a retransmission request packet containing the number of the radio packet that has not arrived, and sends it to the radio packet division circuit 3b. The wireless packet division circuit 3b divides the transmitted retransmission request packet into wireless packets, which are transmission data units, as in the case of ordinary digitized voice data, and temporarily stores the packet in the memory 4b. afterwards,
When the transmission timing comes, the wireless packet division circuit 3b extracts the data for one transmission from the memory 4b, adds a header necessary for synthesizing the packet to the data, and then outputs the error detection code in the error detection encoding circuit 5b. In addition, an error correction code is added by an error correction coding circuit 6b, modulation is performed by a modulator 7b, frequency conversion is performed by a transmitter 8b, and then output from an antenna 9b.

[0007] The signal output from the antenna 9b propagates in free space, is input from the antenna 10a of the opposing base station apparatus, and is frequency-converted in the receiver 11a. After demodulated by the demodulator 12a, the frequency-converted signal is decoded using the error correction code in the error correction coding circuit 13a, and thereafter, the error is detected by the error detection coding circuit 14a using the error detection code. Here, if no error is detected, the received data is transmitted to the wireless packet synthesis circuit 15a.
And temporarily transfer it to the memory 16a. When all the wireless packet headers for packet combining are completed, the wireless packet combining circuit 15a combines the data according to the header to create a user packet.

Here, if the user packet is a retransmission request packet, the retransmission control circuit 19a notifies the radio packet division circuit 3a to prepare a packet requested by the retransmission request packet, and the radio packet division circuit 3a While preparing to extract more predetermined packets,
The retransmission control circuit 19a creates data indicating that data is output according to the retransmission request. When this data is output to the wireless packet division circuit 3a, a wireless packet is output in the same manner as the above-described user packet. On the other hand, when the wireless packet received by the receiving side of the mobile station apparatus in the same manner is received by the wireless packet combining circuit 15b, if all wireless packet headers for packet combining are prepared, the wireless packet combining circuit 15b follows the header. The data is synthesized and a user packet is created.
Here, when the user packet is the partially retransmitted data, the partial retransmitted data is extracted from the partially retransmitted wireless packet number at the beginning of the data and combined with the missing wireless packet data stored in the memory 16b. , Construct user packet data. Here, when an error is detected by the error detection circuit for the partially retransmitted data, the same processing as the above-described processing is performed, and a partial retransmission of the wireless packet data is requested to the base station apparatus side. Repeat this until all have been collected. As described above, the structure of the user packet is established.

[0009]

With the development of digital mobile communication systems in recent years, more advanced anti-fading techniques are required, and there is a problem how to realize those techniques. However, in the method described above, when the influence of a weak electric field or fading is large, the error rate of a wireless packet increases, a packet error occurs regardless of how many times a wireless packet is transmitted, and the number of retransmissions of the wireless packet increases. As a result, there has been a problem that the line use efficiency is reduced. The present invention has been made to eliminate the drawbacks of communication devices having the conventional partial retransmission control and error correction and error detection functions as described above,
An object of the present invention is to provide a time diversity circuit using partial retransmission data with improved error correction capability.

[0010]

In order to achieve the above-mentioned object, a time diversity circuit using partial retransmission data according to the present invention has the following configuration. An antenna for reception, a receiver for converting a received radio signal to a frequency that can be processed by the demodulator, a demodulator for converting an analog signal output by the receiver to a digital signal, and storing data from the demodulator A memory, a data synthesizing circuit that synthesizes demodulator output data and data stored in the memory, an error correction encoding circuit that performs soft decision decoding based on the data, and performs an error detection process according to the error detection code An error detection encoding circuit, a wireless packet combining circuit that combines a plurality of wireless packets into user packets from position information of wireless packet data in the data, a conversion circuit that converts digital data that is a user packet into an analog signal, A retransmission control circuit for issuing a retransmission request when a drop of a radio packet is detected by error detection in the radio packet synthesis circuit; The radio packet division circuit for performing an addition of a header indicating the decomposition and positional relationship of the wireless packet data Zapaketto, the error detection coding circuit for adding an error detection code for error detection,
An error correction encoding circuit for adding an error correction code, a modulator for converting digital data to analog data, and a transmitter for frequency-converting the analog signal to a predetermined frequency;
A transmission antenna for outputting the transmission signal is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. First, before showing an embodiment of the present invention, a peripheral technique according to the present invention will be described. First, an error correction coding circuit is used.The error correction code used here adds data based on a certain rule called a detection code to data to be transmitted called information data to increase redundancy. This is a code that transmits after transmission, and estimates the error location and its error value from the information data and the detection code on the receiving side, and corrects the error by taking the difference between the error value and the received data. This error correction code is created based on rules that maintain linearity when creating the detection code. Also, the error correction code estimates and corrects an erroneous part and its error value when correcting an error, but if the erroneous part is clear, it is only necessary to estimate the error value. It has the characteristic that the correction ability increases. this is,
For example, when it is not possible to determine whether the received data is 0 or 1, and when such received data is handled, it is called erasure decoding. When erasure decoding is performed as described above,
The error correction capability is improved as compared with the case where it is not performed.

Next, the time diversity technique will be described. This technique is to reduce the number of data errors by transmitting the same data a plurality of times. In the case of the conventional method, since the header portion is different even if the data portion is the same, the detection code portions of the error correction code and the error detection code for adding the detection code as information data thereof are completely different, and as a result, Only a method called selection diversity can be used. In general, combining diversity is also known as combining diversity in addition to selection diversity, and is a method of combining data received a plurality of times to create new received data. It is generally known that this method has better reception characteristics than selection diversity.

Next, the partial retransmission control will be described. FIG. 2 is a block diagram showing one embodiment of the partial retransmission control according to the present invention. In the partial retransmission control, as shown in FIG. 2, a user packet of an arbitrary length is divided into radio packets of a predetermined length by a radio packet division circuit, and a header indicating the order of division into each packet is added and transmitted. . When a wireless packet that is not reproduced due to an error or the like occurs at the transmission destination, the unreachable wireless packet is determined from the headers of the wireless packets before and after the wireless packet, and a partial retransmission request signal is notified to the transmitting side. In accordance with the notified partial retransmission request signal, the transmitting side retransmits the data in which the header numbers of the wireless packets to be partially retransmitted and the requested data are added with a header. Since the same data is sent as the data requested to be retransmitted at the time of the failure, if the number of data in which the header numbers are listed is shorter than the data length of the wireless packet, NULL data is inserted and corrected. Each data is transmitted after adding a header which resembles retransmission data to a user packet. Therefore, on the receiving side, the radio packet is synthesized after collecting all the packet data, and the radio packet including the data listing the header numbers is received for the partial retransmission control data without analyzing the data of the user packet. If the analysis can be performed at the time, it is possible to determine what data the subsequent wireless packet is.

An embodiment of the present invention will be described below based on the peripheral technology described above. FIG. 1 is an embodiment showing a configuration of a digital mobile communication system according to the present invention,
(A) shows a base station apparatus, and (b) shows a mobile station apparatus facing the base station apparatus. In addition, in the reference numerals in FIG. 1, a is attached to the base station device side and b is attached to the mobile station device side. The transmitting side of both the base station apparatus and the mobile station apparatus includes microphones 1a and 1b, voice coding circuits 2a and 2b for digitizing voice, radio packet dividing circuits 3a and 3b for dividing into radio packets, and memory 4
a, 4b, error detection coding circuits 5a, 5b for adding error detection codes, error correction coding circuits 6a, 6b for adding error correction codes, modulators 7a, 7b, and a transmitter 8
a and 8b and transmission antennas 9a and 9b. On the other hand, the receiving side includes receiving antennas 10a and 10b,
Receivers 11a and 11b, demodulators 12a and 12b, and an error correction encoding circuit 13 that performs decoding using an error correction code
a, 13b and an error detection coding circuit 14 for performing error detection
a, 14b, wireless packet combining circuits 15a, 15b for creating user packets, and memories 16a, 16b
And audio decoding circuits 17a and 17 for converting into analog signals
b, speakers 18a and 18b, retransmission control circuits 19a and 19b for generating retransmission request packets, and data combining circuits 20a and 20b for generating a difference code and correcting data.
b and memories 21a and 21b.

The operation of FIG. 1 will be described with reference to the operation when digital data is transmitted from the base station apparatus to the mobile station apparatus. An analog signal such as voice is converted into an electric signal by the microphone 1a on the transmitting side of the base station apparatus. After that, the data is converted into digital data by the voice coding circuit 2a. The converted digital data is transmitted to the wireless packet division circuit 3a.
, The data is divided into wireless packets, which are transmission data units for each transmission, and are stored in the temporary memory 4a. When the transmission timing comes, the wireless packet division circuit 3a extracts the data for one transmission from the memory 4a, adds a header necessary for synthesizing the packet to the data, and adds an error detection code by the error detection encoding circuit 5a. Further, an error correction code is added by an error correction encoding circuit 6a, modulation is performed by a modulator 7a, and a desired frequency is converted by a transmitter 8a, and then output from an antenna 9a.

When the signal output from the antenna 9a propagates through free space and is input from the antenna 10b of the opposing mobile station apparatus, the signal is input to the demodulator 12 via the receiver 11b which converts the signal to a desired frequency, and the analog signal is converted. After being converted into a digital signal, the signal is sent to the data synthesizing circuit 20b and stored, and at the same time, decoding is performed using the error correction code in the error correction coding circuit 13b.
, An error is detected by an error detection code. If no error is detected, the data combining circuit 20b discards the data related to the wireless packet, and sends the received data to the wireless packet combining circuit 15b.
Temporarily transfer to. At the same time, the radio packet combining circuit 15b checks whether the data is retransmission request data. Here, in the case of normal data, the following normal processing is performed. The wireless packet synthesizing circuit 15b monitors the header of the wireless packet and repeats the temporary transfer of the received data to the memory 16b until the last wireless packet arrives. Therefore, when all the wireless packet headers for packet combining are completed, the wireless packet combining circuit 15b combines the data according to the header, and
Create a user packet. This user packet is output to the audio decoding circuit 17b, which converts it into an analog signal and sends it out to the speaker 18b.

If an error is detected in the data by the error detection coding circuit 14b using the error detection code, all the headers are not aligned in the wireless packet synthesis circuit 15b. In this case, a retransmission request packet is transmitted as in the conventional technique. The transmitting side retransmits data based on the retransmission request packet in the same manner as in the related art. The data to be retransmitted is decomposed by the radio packet dividing circuit 3a into radio packets, which are transmission data units per transmission, and stored temporarily in the memory 4a, like normal digitized voice data. At the subsequent transmission timing, the wireless packet division circuit 3a extracts the data for one transmission from the memory 4a and adds a header necessary for synthesizing the packet to the data. Further, an error detection code is added by the error detection coding circuit 5a, and the error correction coding circuit 6a
After an error correction code is added thereto, modulation is performed by the modulator 7a and frequency conversion is performed in the transmitter 8a.
Output from a.

When the signal output from the antenna 9a propagates in free space and is input from the antenna 10b of the opposing mobile station, the signal is input to the demodulator 12 via the receiver 11b that converts the signal to a desired frequency, and demodulated. Further, the data is input to the data synthesizing circuit 20b and stored in the memory 21b, and at the same time, the decoding is performed using the error correction code by the error correction coding circuit 13b. Is detected. Here, when no error is detected, the received data is sent to the wireless packet combining circuit 15b, and further temporarily transferred to the memory 16b. At this time, the wireless packet combining circuit 15b determines whether or not the data is a list of retransmission items of the partial retransmission control, and if so, the wireless packet data following the header could not be reproduced before. The difference between the headers of the wireless packet data is calculated and output to the data combining unit 20b. The data combining circuit 20b generates a difference error correction code and a difference error detection code for the difference between the headers, and adds the difference error correction code and the difference error detection code to the previous wireless packet data stored in the memory 21b to make correction.

When the next wireless packet data is demodulated from the demodulator 12b, the data is decoded by the error correction coding circuit 13b using the error correction code, and the error is detected by the error detection coding circuit 14b. The corrected wireless packet data and the currently transmitted wireless packet data are combined to generate lost data. If the error detection encoding circuit 14b detects an error and cannot reproduce the wireless packet data, the data combining circuit 20b
Is input to the error correction coding circuit 13b, and is decoded using the error correction code. The error detection coding circuit 14b detects an error using the error detection code.

FIG. 3 is a flowchart showing the operation flow of the digital mobile communication system according to the present invention. Referring to the figure, a case where data is transmitted and received from the transmission side to the reception side will be described. First, on the transmission side, an analog signal such as voice is input from a microphone (step S10).
1), digitized by a voice coding circuit (step S2), divided into wireless packets as transmission data units, and stored in a memory (steps S3, S4). Next, when the transmission timing of the wireless packet comes (step S5),
The data for one transmission is extracted from the memory, and a header necessary for packet synthesis is added (step S6). afterwards,
After adding an error detection code (step S7) and an error correction code (step S8), the signal is output from the antenna through modulation and frequency conversion (step S9). Further, the above operation is continued until the data transmission is completed (step S10). On the receiving side, the radio wave propagated in the free space is input from a receiving antenna, undergoes frequency conversion (step S11), undergoes demodulation to receive digital data (step S12), and performs decoding using an error correction code (step S13). ). Next, an error is detected using an error detection code (step S14).
The partial retransmission data is detected (step S15). If it is not detected here, the wireless packet is repeatedly stored in the memory until the final wireless packet arrives (step S16) (step S17). When the final wireless packet arrives, the wireless packet data is combined according to the header of the wireless packet to create a user packet (step S18). Thereafter, the digital data is converted into an analog signal (step S19) and output from the speaker (step S20).

On the other hand, if the receiving side detects an error in the error detection using the error detection code (step S14), it confirms that the last wireless packet has arrived (step S21), and then generates a retransmission request packet. (Step S22), normal packet transmission processing is performed (step S23), and modulation and frequency conversion are performed (step S2).
4) Output from the antenna. The radio wave that has propagated in the free space is input from the receiving antenna on the transmitting side, undergoes frequency conversion and demodulation (step S25), and performs normal packet reception processing (step S26). When a retransmission request packet is detected when combining wireless packets (step S2).
7), perform retransmission control and create retransmission data (step S
28), the wireless packet is decomposed (step S3).

Next, when the partial retransmission data is detected on the receiving side (step S15), the difference between the headers of the newly transmitted wireless packet data and the previously unreproducible wireless packet data is calculated (step S30). ,
A difference error correction code (step S3
1) and a differential error detection code (step S32) are generated and added to the previous wireless packet data to make a correction (step S33). The corrected wireless packet data and the currently transmitted wireless packet data are combined to create lost data (step S34).

[0023]

As described above, according to the present invention, since the second combined data is temporally combined diversity, the error correction capability is further improved, and the probability that wireless packet data can be reproduced is increased. Therefore, it is possible to increase the recall rate of the wireless packet data by the retransmission control, so that a great effect is exhibited in the operation of the system.

[Brief description of the drawings]

FIG. 1 is an embodiment showing a configuration of a digital mobile communication system according to the present invention.

FIG. 2 is a block diagram showing an embodiment of the partial retransmission control according to the present invention.

FIG. 3 is a flowchart showing an operation flow of the digital mobile communication system according to the present invention.

FIG. 4 is an example showing a configuration of a conventional digital mobile communication system.

[Explanation of symbols]

 1a, 1b microphone 2a, 2b voice coding circuit 3a, 3b wireless packet division circuit 4a, 4b memory 5a, 5b error detection coding circuit 6a, 6b error correction coding circuit 7a, 7b ··· modulator 8a, 8b ··· transmitter 9a, 9b ··· antenna 10a, 10b ··· antenna 11a, 11b ··· receiver 12a, 12b ··· demodulator 13a, 13b ··· error correction coding circuit 14a, 14b error detection coding circuit 15a, 15b wireless packet synthesis circuit 16a, 16b memory 17a, 17b voice decoding circuit 18a, 18b speaker 19a, 19b retransmission control circuit 20a, 20b ..Data combining circuits 21a and 21b..Memory

Claims (1)

[Claims] An antenna for reception, a receiver for converting a received radio signal to a frequency that can be processed by a demodulator, a demodulator for converting an analog signal output from the receiver into a digital signal, and a demodulator. Memory for storing the data of
A data synthesizing circuit for synthesizing demodulator output data and data stored in the memory, an error correction encoding circuit for performing soft decision decoding based on the data synthesizing circuit, and an error detection code for performing error detection processing according to the error detection code Wireless packet combining circuit for combining a plurality of wireless packets into user packets from position information of wireless packet data in the data; a converting circuit for converting digital data as user packets into analog signals; A retransmission control circuit that issues a retransmission request when a dropout of a wireless packet is detected by an error detection circuit; a wireless packet division circuit that disassembles a user packet and adds a header indicating the positional relationship of wireless packet data; Error detection coding circuit to add error detection code and error correction code to add error correction code A partial retransmission data comprising a circuit, a modulator for converting digital data into analog data, a transmitter for converting the frequency of the analog signal to a predetermined frequency, and a transmission antenna for outputting the transmission signal. Time diversity circuit using