JPH06224837A - Portable radio telephone set - Google Patents

Abstract

PURPOSE:To provide a portable radio telephone set capable of satisfactorily maintaining speech quality even in a codition that radio wave environment is not satisfactory. CONSTITUTION:A transmission side is provided with a means 1 which converts a voice signal into digital voice data, a transmission buffer 20 which stores the voice data, and an error encoding part 3. A reception side is provided with an error detecting part 8 of the received voice data, a reception buffer 90 which stores the voice data, and an analog converting means 10 which converts the voice data into the voice signal. In the portable radio telephone set in which the voice data are made to a slot, and transmitted and received, plural voice data are stored in the transmission and reception buffers 20 and 90, and the same voice data stored in the transmission buffer 20 are transmitted plural times from the transmission side while hourly shifted. The reception side is equipped with a selecting part 13 which selects one of the same voice data stored in the reception buffer 90, and the detected result of the error detecting part 8 is communicated to the selecting part 13. In the reception side, the voice data without any error are selected from among the same voice data received plural times, and the voice signal is reproduced, so that the transmission error rate can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division multiple access (TDMA) type digital portable radio telephone, and is particularly configured to maintain good call quality even in a bad radio environment.

[0002]

2. Description of the Related Art A conventional digital portable radio telephone is shown in FIG.
As shown in FIG. 2, as a configuration block on the transmission side, an input unit 1 for converting an audio signal input from a microphone (not shown) into digital audio data, a transmission buffer 2 for accumulating the audio data, and an audio data base. Cyclic redundancy code (CR
An error code unit 3 for calculating an error code such as C); a slot unit 4 for configuring voice data, error code, etc. in slots;
And a demodulation unit 6 for frequency-converting a radio-frequency signal into a baseband signal as a component block on the receiving side. , An inverse slot unit 7 for dividing the received slot into voice data, error code, etc.
An error detection unit 8 for detecting whether or not an error has occurred during the transmission of the voice data based on the error code of the received voice data, a reception buffer 9 for accumulating the voice data,
A reproduction unit 10 for converting voice data into an analog voice signal is provided, and further, an antenna 11 for transmitting and receiving radio waves and a switching unit 12 for switching the connection of the antenna 11 to the modulation unit 5 or the demodulation unit 6 in accordance with transmission or reception. It has and.

Further, in the time division multiple access (TDMA) system, a frequency channel for transmitting a signal by one carrier frequency is used as a plurality of transmission lines, so that the frequency channel is divided into frames at regular time intervals. Then
Communication between the communication devices is performed using a pair of time positions (time slots) assigned in this frame.

For example, as shown in FIG. 4, the frequency channel is divided into frames at intervals of Tm seconds, and each frame has 8 frames.
When divided into four time slots, the first four time slots S1 to S4 are for forward transmission, and the next four time slots R1 to R4 are for reverse transmission. Between the assigned communication devices, one device uses S1 for transmission and the other device uses R1 for transmission, using forward and reverse paired time slots, eg, S1 and R1. Then, full-duplex communication is performed between them. Each slot is composed of a preamble for synchronization, voice data, error code, and the like.

In the portable radio telephone shown in FIG. 3, the voice signal input from the microphone is converted into digital voice data by the input unit 1, and the voice data obtained by digitally converting the voice signal of one frame interval (Tm seconds) is transmitted every Tm seconds. Are stored in the transmission buffer 2. The accumulated voice data is sent to the error coding unit 3 in accordance with the processing speed of the error coding unit 3, where an error code such as a cyclic redundancy code (CRC) is calculated based on the voice data, and the slot unit 4 In, 1 slot is formed by a combination of a preamble, voice data, an error code, and the like.

The baseband data is converted into a radio frequency by the modulator 5 and transmitted as radio radio waves through the switching unit 12 and the antenna 11 at every frame interval using the same slot (for example, S1).

On the other hand, the radio signal of the same slot (for example, R1) received via the antenna 11 and the switching unit 12 is frequency-converted into a baseband signal by the demodulation unit 6, and the voice data and error code etc. are inputted by the inverse slot unit 7. Is divided into and The error detection unit 8 detects whether or not the received voice data contains an error during transmission, based on the error code. Next, the audio data is accumulated in the reception buffer 9, converted into an analog audio signal by the reproducing unit 10, and output from the speaker.

At this time, when the error detection unit 8 detects an error in the voice data, the voice data is not directly reproduced, but an error is included based on the voice data correctly received before and after the slot. The correct appearance of the audio data is estimated, and the audio signal is reproduced by the corrected audio data.

[0009]

However, in the conventional portable radio telephone, when the environment of radio wave propagation is bad, the error rate of transmission increases, so that the accuracy of correction of voice data decreases and the reproduced voice signal is reproduced. However, there is a problem that the call quality is deteriorated.

The present invention solves these conventional problems, and an object of the present invention is to provide a portable radio telephone capable of maintaining good call quality even in a bad radio environment.

[0011]

Therefore, in the present invention, on the transmitting side, a converting means for converting an audio signal into digital audio data, a transmitting buffer means for storing the converted audio data, and an error code for the audio data. The receiving side includes error detecting means for detecting an error in the received voice data, receiving buffer means for accumulating the voice data, and converting means for converting the voice data into an analog voice signal. In a portable wireless telephone configured to transmit and receive voice data in slots, the transmission buffer means and the reception buffer means are configured to store a plurality of voice data, and the same voice data stored in the transmission buffer means is stored. It is transmitted multiple times with a time shift from the transmitting side, and the receiving side selects one from the same audio data stored in the receiving buffer means. Selection means for providing, are configured to notify the detection result of the error detecting means to the selection means.

[0012]

Therefore, the same voice data is transmitted from the transmitting side a plurality of times at different times, and the receiving side selects the voice data having no error from the same voice data received a plurality of times. Play the audio signal. Therefore, the transmission error rate of voice data is reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A portable radio telephone according to an embodiment of the present invention is
As shown in FIG. 1, in the configuration block on the transmission side, the transmission buffer 20 has a structure capable of storing a plurality of audio data obtained by digitally converting one frame of audio signal, and in the configuration block on the reception side, The reception buffer 90 has a structure capable of accumulating a plurality of received audio data,
The selector 13 is provided for selecting the audio data to be reproduced from this reception buffer. The error detection unit 8 notifies the selection unit 13 of the error detection result of each audio data, and the selection unit 13 selects the audio data that does not include an error. Other configurations are the same as those of the conventional device (FIG. 3).

In this telephone, the voice signal input from the microphone is converted into digital voice data by the input unit 1, and
The audio data obtained by digitally converting the audio signal of the frame interval (Tm seconds) is sent to the transmission buffer 20 every Tm seconds.
The transmission buffer 20 capable of accumulating a plurality of (n) pieces of this audio data sequentially accumulates the audio data, and then outputs the same audio data a plurality of times with a temporal shift.

The output voice data is output to the error coding unit 3
The error code such as a cyclic redundancy code (CRC) is calculated based on the voice data, and the slot unit 4 forms one slot including a combination of the preamble, the voice data, and the error code. .

The baseband data is converted into an unvoiced frequency by the modulator 5 and is wirelessly transmitted via the switching unit 12 and the antenna 11 using the plurality of transmission slots in FIG.

FIG. 2 shows a time chart at this time. The audio signal (1) has a time domain divided by one frame interval (Tm seconds) at each time T1, T2, ..., Tk,
.. is converted into digital audio data Ak and input to the transmission buffer 20. When the transmission buffer 20 is configured to be able to store three pieces of audio data Ak, A (k-1), and A (k-2), the same audio data is output twice at different times. The same audio data is output again from the transmission buffer three frames later by a method such as reading across, and the audio data Ak output twice is transmitted through the transmission slot S1 (2) and the transmission slot S3, respectively.
(3) and are transmitted.

As a result, the transmission slot S of the T2 frame
1, the voice data A1 is transmitted, the voice data A2 is transmitted in the transmission slot S1 of the T3 frame, and the voice data A (k-1) is transmitted via the antenna 11 in the transmission slot S1 of the Tk frame. Become. Furthermore, T
In the transmission slot S3 of 4 frames, the audio data A1 is
Further, the audio data A2 is transmitted in the transmission slot S3 of the T5 frame, and A (k-3) is transmitted via the antenna 11 in the transmission slot S3 of the Tk frame. The audio data Ak transmitted by the transmission slot S3 is displayed as Bk for the sake of explanation.

On the other hand, on the receiving side, the receiving slots R1 and R3 corresponding to the transmitting slots S1 and S3 (FIG. 4).
To receive. The received signal of each slot is frequency-converted into a baseband signal by the demodulation unit 6, and is divided into voice data and error code by the inverse slot unit 7. The error detector 8 detects whether or not the received voice data contains an error in the middle of transmission based on the error code, and outputs the voice data to the reception buffer 90 one after another.

A plurality of audio data are accumulated in the reception buffer 9, and two audio data relating to the same audio signal are read out by the selection unit 13 from the audio data. Therefore, the receive buffer 90 receives A1, A2, and A after receiving the T4 frame.
The voice data of 3 and B1 are stored, and the voice data of A2, A3, A4 and B2 are stored after the reception of the T5 frame. That is, after receiving the Tk frame, A
(K-3), A (k-2), A (k-1) and B (k
-3) The voice data is stored.

Upon receiving the notification of the error detection result from the error detection unit 8, the selection unit 13 receives the error-free speech from the read A (k-4) and B (k-4) at the start time of the Tk frame. Select data. The selected audio data is converted into an analog audio signal by the reproduction unit 10 and output from the speaker.

Therefore, the reproduction signal (4) starts from the T5 frame, and in each frame such as A1, B2, A3, B4, B5, A6, the reception slot R is received.
The signal is reproduced from either one of the audio data received at 1 or R3.

When the voice data Ak and Bk received by the error detection unit 8 both include an error in the middle of transmission, the voice data is not directly reproduced, but the slot is directly reproduced, as in the conventional case. Based on the voice data correctly received before and after, the correct appearance of the voice data including an error is estimated and the voice signal is reproduced.

In the portable radio telephone according to the present invention, the data relating to the same signal can be received a plurality of times before and after in time, and the error-free data can be selected from among them, so that the error rate of radio wave transmission is lowered. Therefore, even when estimating the correct appearance of voice data including an error, correct estimation is possible.

The transmission buffer 20 and the reception buffer
In 90, in order to read the audio data in a desired order, it is possible to use a known method such as controlling the reading order of randomly stored data or reading from a plurality of locations at the rear end and the middle of the FIFO memory. it can.

[0026]

As is apparent from the above description of the embodiments, the portable radio telephone of the present invention suppresses the increase of the transmission error rate and maintains the good communication quality even in a bad radio wave propagation environment. can do.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a portable wireless telephone of the present invention,

FIG. 2 is a time chart of transmission / reception in the portable wireless telephone of the embodiment,

FIG. 3 is a block diagram showing a configuration of a conventional portable wireless telephone,

FIG. 4 is a diagram showing a channel and slot configuration in a conventional time division multiple access system.

[Explanation of symbols]

 1 input section 2 and 20 transmission buffer 3 error code section 4 slot section 5 modulation section 6 demodulation section 7 reverse slot section 8 error detection section 9 and 90 reception buffer 10 reproduction section 11 switching section 12 antenna 13 selection section

Claims (1)

[Claims] 1. The receiving side comprises a conversion means for converting an audio signal into digital audio data, a transmission buffer means for accumulating the converted audio data, and an error encoding means for the audio data. On the side, there is provided an error detecting means for detecting an error in the received voice data, a receiving buffer means for accumulating the voice data, and a converting means for converting the voice data into an analog signal as an analog signal. In the portable wireless telephone configured to transmit and receive, the transmission buffer means and the reception buffer means store a plurality of the voice data, and the same voice data stored in the transmission buffer means is temporally transmitted from the transmission side. It is selected by selecting one of the same audio data stored in the receiving buffer means, and transmitting to the receiving side by shifting a plurality of times. We have a means to choose
A portable radio telephone characterized in that the selection means is notified of the detection result of the error detection means.