JP2001238256A - Variable rate coding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable speed coding system that conducts coding at a proper speed even when a signal in a transmission band is interrupted by solving a problem of a conventional variable speed coding system that the system cannot encode signals at a proper speed because speed control information is not transmitted when the signal in a transmission band is interrupted. SOLUTION: The variable speed coding system uses an outgoing channel quality selection section 19 or an incoming channel control selection section 27 to select the control information of transmission power correlated with the state of channel quality when the signal in the transmission band is interrupted so as to adapt to the coding and transmits the signal by rearranging bit allocation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a variable rate coding system applied to a CDMA wireless network.
In particular, even if the signal in the transmission band for transmitting audio etc. is interrupted,
The present invention relates to a variable rate encoding system that can perform encoding at an appropriate rate.

[0002]

2. Description of the Related Art In general, in wireless communication, line quality is largely changed, and as one method for securing stable communication quality, European mobile radio (Group Special Mobile:
There is Adaptive Multi Rate (GSM-AMR, hereinafter abbreviated as AMR) standardized by GSM. The AMR monitors the quality of the uplink and the downlink, and adaptively changes the ratio between the number of bits of transmission data (for example, voice data) and the number of bits of an error correction code per frame depending on the state of the line quality. This is a communication method to be performed. For example, when the radio line quality is good,
Since it is not necessary to increase the error correction capability, the number of bits of the error correction code is reduced, and the number of bits of the audio data is increased accordingly, thereby increasing the transmission speed of the audio data. On the other hand, when the radio channel quality is poor, it is necessary to increase the error correction capability. Therefore, the number of bits of the error correction code is increased, and the number of bits of the audio data is reduced accordingly. As a result, the transmission speed of the audio data is reduced. Will be. In other words, the transmission rate of the voice data and the transmission rate of the error correction code can be varied by adaptively changing the combination of the number of bits of the transmission data (voice data) and the number of bits of the error correction code according to the line quality situation. The coding rate (transmission rate) of the entire frame is not changed, and the overall transmission quality is ensured by adaptively enhancing the error correction capability according to the line quality.

In AMR, as means for notifying the receiving side of information on the combination of the number of transmission data bits and the number of error correction code bits in transmission data adapted on the transmission side, information on the combination of the number of bits, ie, the transmission speed The information is transmitted as speed control information in the form of in-band data of a voice-encoded signal transmission band together with voice-encoded data,
A method is adopted in which the receiving side receives in-band data, determines the combination of the number of bits of the received data from the speed control information embedded in the in-band data, and decodes the combination.

A conventional variable rate coding system will be described with reference to FIG. FIG. 2 is a configuration block diagram of a conventional variable rate coding system. The conventional variable rate coding system is mainly composed of a base station 1 'for performing bidirectional voice transmission / reception and a mobile terminal 2', a downlink from the base station 1 'to the mobile terminal 2', and a mobile terminal 2 '. 'Is wirelessly connected to the base station 1' via an uplink.

[0005] Then, the base station 1 '
A downlink speed control unit 12, a transmission line encoder 13, an uplink speed control unit 14, a baseband processing unit 15 ', a radio unit 16, a transmission line decoder 17, and a speech decoder 18. Have been. Also, the mobile terminal 2 ′
, A baseband processing unit 22, a transmission path decoder 23,
Speech decoder 24, speech encoder 25, transmission path encoder 2
6 is comprised.

Next, each section of the conventional variable rate coding system will be described. First, each section in the base station 1 'will be described. The audio encoder 11 compresses and encodes an audio signal at a speed adapted to the line quality. Specifically,
The speech encoder 11 receives a speech signal, compresses and encodes the speech signal at a speed specified by a downstream speed control signal input from the outside, and outputs a coded speech. Here, for the downlink speed control signal, an appropriate combination of the number of bits of the audio signal and the number of bits of the error correction code in the downlink is determined according to the downlink quality measured by the mobile terminal 2 ', and the downlink speed control signal is It was output.

[0007] The transmission line encoder 13 performs transmission line encoding of the encoded voice and information indicating the adapted speed at a speed adapted to the line quality. Specifically, the transmission path encoder 13
Is to input coded voice and perform transmission path encoding at a rate specified by the above-described downlink rate control signal input from the outside. At this time, the downlink rate required when decoding is performed on the receiving side A control signal, and an uplink speed control signal for designating the uplink speed are also input from outside, and the audio data and the uplink,
It generates and outputs an in-band signal (encoded signal) including a downstream speed control signal. Here, an appropriate combination of the number of bits of the audio signal and the number of bits of the error correction code in the uplink is determined for the uplink rate control signal according to the uplink quality measured by the base station 1 '. It was output.

The baseband processing unit 15 'receives a coded signal to be transmitted, modulates and outputs a baseband signal as a function on the transmitting side, and has a function on the receiving side as a function on the receiving side.
It receives a baseband signal, demodulates it, and outputs a coded signal. Also, the baseband processing unit 1
5 ', as a function on the receiving side, checks the quality of the uplink, calculates information indicating the channel quality, and outputs it as an uplink quality signal. Here, as the information indicating the channel quality, SIR (Signa) indicating the signal-to-interference power ratio of each channel is used.
l Interference Ratio) and SIR
RSCP (Receive Signal Compensation) indicating the desired signal level corrected by the received signal strength (RSSI) at 6
Power).

The radio section 16 receives a baseband signal as a function on the transmission side, radiates it into space as a radio signal, and receives a radio signal from space and converts it into a baseband signal as a function on the reception side. And output it.

The transmission path decoder 17 performs transmission path decoding of the received coded signal using the coding speed adapted on the transmission side. Specifically, the transmission path decoder 17 inputs the received encoded signal, first extracts and outputs the received uplink speed control signal incorporated in the encoded signal, and outputs the uplink speed control signal from the extracted uplink speed control signal. Then, it determines at what speed the received encoded speech signal is encoded on the transmitting side. Then, transmission path decoding is performed according to the determined encoding speed, and the received encoded voice from the mobile terminal 2 'and the downlink quality signal incorporated in the mobile terminal 2' are output.

The speech decoder 18 decodes the received coded speech at a coding rate adapted on the transmission side. Specifically, the speech decoder 18
The received upstream speed control signal extracted in step (1) is input, the input coded voice is expanded at a speed based on the upstream speed control signal, voice decoded, and a decoded voice is output.

The downlink speed control unit 12 determines a coding rate adapted to the downlink according to information input from the outside indicating the quality of the downlink, and outputs a downlink rate control signal for controlling the coding rate of the downlink. Generate and output. Specifically, the downlink speed control unit 12 inputs information indicating the quality of the downlink from the outside, and according to the quality, increases the bit allocation for voice when the channel quality is good, and increases the bit allocation for the voice when the channel quality is poor. And generates and outputs a downlink speed control signal for performing control to increase the bit allocation for error correction.
As a method of determining the coding rate, information on bit allocation with respect to the line quality is stored as a mode in software or on a memory in a table or the like in advance, and the mode associated with the input line quality is determined as the coding rate. However, the method is not limited to this. Also,
In the conventional downlink speed control unit 12, a downlink quality signal from the transmission path decoder 17 is input as information indicating downlink quality, and a downlink speed control signal is generated according to the quality.

An uplink rate control unit 14 determines an encoding rate adapted to the uplink according to information indicating the quality of the uplink inputted from the outside, and generates an uplink rate control signal for controlling the encoding rate of the uplink. Generate and output. Specifically, in the uplink speed control unit 14, the baseband processing unit 1
5 ', an uplink / downlink quality signal indicating the quality of the uplink is input. According to the quality, the bit allocation for voice is increased when the line quality is good, and the bit allocation for error correction is performed when the line quality is bad. Perform control to increase bit allocation,
It generates and outputs an uplink speed control signal. The method of determining the coding speed is the same as that of the downlink speed control unit 12.

Next, each section in the mobile terminal 2 'of the conventional variable rate coding system will be described. The wireless unit 21
Similar to the radio section 16 of the base station 1 ', a baseband signal is input as a function on the transmitting side and is radiated into space as a radio signal, and a radio signal is received from space as a function on the receiving side. It is converted into a band signal and output.

[0015] The baseband processing unit 22 'is a base station 1'.
In the same manner as the baseband processing unit 15 ', a coded signal to be transmitted is input as a function on the transmission side, and a baseband signal is output after modulation, and a received baseband signal is input as a function on the reception side. Then, it demodulates and outputs an encoded signal. Also, a baseband processing unit 22 '
As a function on the receiving side, checks the quality of the downlink, calculates information indicating the channel quality, and outputs it as a downlink quality signal.

The transmission path decoder 23 performs transmission path decoding on an encoded signal received at an encoding speed adapted on the transmission side. Specifically, the transmission path decoder 23 inputs the received encoded signal, first extracts and outputs the received downlink speed control signal incorporated in the encoded signal, and outputs the downlink speed control signal from the extracted downlink speed control signal. Then, it determines at what speed the received encoded speech signal is encoded on the transmitting side. Then, in accordance with the determined encoding speed, transmission path decoding is performed, and the received encoded voice from the base station 1 ′ and
The base station 1 'outputs the incorporated upstream speed control signal.

The speech decoder 24, like the speech decoder 18 of the base station 1 ', performs speech decoding of the received encoded speech at an encoding speed adapted on the transmission side. Specifically, the audio decoder 24 receives the received downlink speed control signal extracted by the transmission line decoder 23, expands the input coded audio at a speed based on the downlink speed control signal, and performs audio decoding. Output decoded sound.

The speech encoder 25 compresses and encodes a speech signal at a speed adapted to the line quality, similarly to the speech encoder 11 of the base station 1 '. More specifically, the speech encoder 25 receives a speech signal, compresses and encodes the speech signal at a speed designated by an externally input uplink speed control signal, and outputs a coded speech. Here, an appropriate combination of the number of bits of the audio signal and the number of bits of the error correction code in the uplink is determined for the uplink rate control signal according to the uplink quality measured by the base station 1 '. This is transmitted from the base station 1 'to the mobile terminal 2'.

The transmission line encoder 26 encodes the coded speech and information indicating the adapted speed at a speed adapted to the channel quality. Specifically, the transmission path encoder 26
Performs coded speech input and performs transmission path coding at a rate specified by the above-described uplink rate control signal input from the outside, and in this case, the uplink rate required when decoding is performed on the receiving side. A control signal and a downlink quality signal which is information indicating downlink quality are also input from the outside, and an in-band signal (encoded signal) including voice data, an uplink speed control signal, and a downlink quality signal is generated and output. Is what you do.

Next, the operation of the conventional variable rate speech coding system will be described with reference to FIG. First, a downlink signal will be described. On the base station 1 'side, a speech signal a input from the network side is compression-encoded in the speech encoder 11 at an adaptive speed specified by the downlink speed control signal c from the downlink speed control unit 12, and is encoded. Output as sound b. Then, the coded voice b is transmitted to the transmission line encoder 13 by the downlink speed control signal c from the downlink speed controller 12.
At the adaptive speed specified by, transmission line coding is performed,
Further, a downlink speed control signal c required for decoding on the receiving side, and an uplink speed control unit 1 for specifying an uplink speed.
4, and the in-band signal (output signal f) is generated and output.

At this time, the downlink speed control signal c is output by the downlink speed control unit 12 in which the adaptive speed in the downlink is determined according to the downlink quality signal y from the transmission line decoder 17. . Also, the upstream speed control signal d
In the uplink speed control unit 14, the adaptive speed in the uplink is determined according to the uplink quality signal e from the baseband processing unit 15 ', and is output.

The output signal f is modulated by the baseband processing section 15 'into a baseband signal g, further converted by the radio section 16 into a radio signal h, radiated into space and transmitted by the downlink. You.

On the mobile terminal 2 'side, the radio signal h
Is received by the radio unit 21, converted into a baseband signal i, demodulated by the baseband processing unit 22 ', and an encoded signal j is output. At this time, the baseband processing unit 22 'checks the quality of the downlink and outputs a downlink quality signal q.

The coded signal j output from the baseband processing unit 22 'is input to the transmission path decoder 23, where the downlink speed control signal k is extracted from the coded signal j. At the same time, the transmission line is decoded at the speed according to the downstream speed control signal k, and the encoded voice 1 and the upstream speed control signal m are output. And
The coded speech 1 is converted by a speech decoder 24 into a transmission path decoder 23.
The audio is decoded at a speed according to the downstream speed control signal k, and a decoded audio n is output.

Next, the upstream signal will be described. On the mobile terminal 2 'side, the input speech signal 0 is
At 5, the code is compressed and encoded at the adaptive rate specified by the uplink rate control signal m from the transmission path decoder 23 (that is, this is the uplink rate control signal d transmitted from the base station 1 '). This is output as the converted voice p. And
The coded speech p is subjected to transmission line encoding at an adaptive speed specified by the uplink speed control signal m from the transmission line decoder 23 in the transmission line encoder 26, and further, when decoded on the receiving side. The required uplink speed control signal m and the downlink quality signal q from the baseband processing unit 22 'indicating the downlink quality are simultaneously handled, and an in-band signal (output signal r) is generated and output.

The output signal r is modulated by the baseband processing section 22 'into a baseband signal s, further converted by the radio section 21 into a radio signal t, radiated into space and transmitted on the uplink. You.

In the base station 1 ', the radio signal t
Is converted into a baseband signal u, demodulated by a baseband processing unit 15 ', and an encoded signal v is output. At this time, the baseband processing unit 15 '
The uplink quality is checked and the uplink quality signal e
Is output.

The coded signal v output from the baseband processing unit 15 'is input to the transmission path decoder 17, and the transmission path decoder 17 extracts the uplink speed control signal w from the coded signal v. At the same time, the transmission path is decoded at a speed according to the uplink speed control signal w, and the encoded voice x and the downlink quality signal y are output. And
The coded voice x is converted by a voice decoder 18 into a transmission path decoder 17.
The audio is decoded at a speed according to the upstream speed control signal w, and the decoded audio z is output to the network side.

Here, the downlink quality signal y from the transmission path decoder 17 is input to the downlink speed control unit 12, and the downlink speed control unit 12 outputs a downlink speed control signal c indicating an adaptive speed according to the quality. Is generated, and the downlink rate control signal c is used as a speech coding rate in the speech encoder 11 and a transmission path coding rate in the transmission path encoder 13, and is used for demodulation in the mobile terminal 2 '. The data is coded in the transmission line together with the voice data by the device 13 and transmitted on the downlink.

The uplink quality signal e from the baseband processing unit 15 'is input to the uplink speed control unit 14,
The uplink speed control unit 14 generates an uplink speed control signal d indicating an adaptation speed according to the quality, and transmits the transmission path as information on the speed adapted to the line quality in the uplink from the mobile terminal 2 ′ to the base station 1 ′. The transmission data is encoded by the encoder 13 together with the voice data, and is transmitted on the downlink.

As described above in detail, the conventional variable rate coding system is a feature of the variable rate coding system by transmitting a line quality signal and a rate control signal using an in-band signal (in-band signaling). A plurality of different combinations of the bit allocation of the voice coding and the error correction coding are set, and an error state of the transmission line (line quality)
, The encoders (11, 13, 25, 26) can adaptively switch this bit allocation.

As a technique for setting the speed in accordance with the line quality, Japanese Patent Application Laid-Open No. 11-1999
No. 298369, "Multi-code adaptive modulation method and transceiver" (applicant: Kokusai Electric Inc., inventor: Masaki Tanaka et al.). This conventional technique measures the line quality in a transceiver capable of varying the data rate, transmits the line quality information as a part of the data, and changes the data rate to be transmitted according to the state of the line quality. Is to extract line quality information from received data and determine the data rate for demodulation.

While the technology and configuration example of the variable rate coding system have been described in detail above, when transmitting and receiving a call voice in a CDMA wireless communication system, the characteristics of the call that one is talking and the other is listening. In consideration of the above, there is a transmission output control function (Voice Operated transmitting: VOX) as a technique for improving communication efficiency.
The VOX control determines whether the data to be subjected to speech coding is noise including speech or noise not including speech. When the speech transitions from voiced to unvoiced, the transmission of the radio frame is stopped, and the speech transitioned from unvoiced to voiced. In this case, transmission of a radio frame is started. That is, when the sender is talking on the telephone or the like, the receiver side often does not speak, and in this case, the transmission data from the receiver side is stopped.

In consideration of the situation when the VOX control is used in the above-described conventional variable rate coding system, the following case can be considered. Normally, the talker rarely utters himself while listening to the other party's voice, so it is easily assumed that the uplink and the downlink are alternately used by VOX control. Therefore, when only the downlink is used, the downlink quality signal q for determining the coding rate of the downlink is not transmitted from the mobile terminal 2 'to the base station 1'. The line quality signal y is not taken out, and the quality of the downlink is not reflected on the downlink speed control signal c. Conversely, when only the uplink is used, the uplink rate control signal d for indicating the coding rate of the uplink is not transmitted from the base station 1 'to the mobile terminal 2'. At 2 ', the uplink quality signal m is not extracted, and the uplink quality is not reflected on the uplink speed control signal m.

[0035]

As described above, in the conventional variable-rate speech coding system, when VOX control is used, transmission of in-band data on either the uplink or the downlink is stopped. Transmission of control information such as line quality and speed control signals (in-band signaling) using the in-band signal is interrupted.

In this case, a plurality of combinations having different bit allocations between voice coding and error correction coding, which are features of the variable-rate voice coding system, are prepared, and the transmission side adaptively adjusts the bit allocation according to the state of the transmission path. There is a problem that it is difficult to switch to.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable speed coding system capable of performing coding at an appropriate speed even if a signal in a transmission band is interrupted. And

[0038]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems of the prior art is characterized in that when a speech signal is transmitted between a base station and a mobile terminal, speech coding and error correction coding are performed. A plurality of combinations having different bit allocations are prepared, the state of the line quality is determined using signals in the transmission band, and the bit rate is adaptively switched and transmitted according to the state of the line quality. An encoding system, in the case where a signal in a transmission band is interrupted, switches the allocation of these bits according to transmission power control information correlated with a state of line quality and transmits the signal. Can be encoded at an appropriate speed even if is interrupted.

Further, the variable rate coding system according to the present invention uses the control information of the transmission power correlated with the state of the line quality even when the signal in the transmission band is not interrupted, so that the speech coding and the error correction coding can be performed. The transmission is performed by adaptively switching the bit allocation, and is not affected by the interruption of the signal in the transmission band.

[0040]

Embodiments of the present invention will be described with reference to the drawings. Note that the function realizing means described below may be any circuit or device as long as the function can be realized, and some or all of the functions may be realized by software. is there. Further, the function realizing means may be realized by a plurality of circuits, or the plurality of function realizing means may be realized by a single circuit.

In the variable rate coding system of the present invention, when transmitting a voice signal between a base station and a mobile terminal, the transmitting side determines the number of bits of the voice signal and the number of bits of the error correction code according to the state of the line quality. The transmission rate of the audio signal and the transmission rate of the error correction code are made variable while the transmission rate information is also transmitted within the transmission band, and the reception side receives the received signal. A variable rate coding system for decoding based on transmission rate information in a transmission band of a mobile terminal, wherein a mobile terminal transmits a speech signal to a base station according to transmission power control information indicating a state of uplink quality. The base station changes the combination of the number of bits and the number of bits of the error correction code. It is intended to change the combination of the number of bits, be interrupted signal in the transmission band, in which no affected.

In the variable rate coding system of the present invention, when transmitting a voice signal between a base station and a mobile terminal, the transmitting side determines the number of bits of the voice signal and the error correction code depending on the state of the line quality. Coding is performed by adaptively changing the combination of the number of bits to make the transmission speed of the audio signal and the transmission speed of the error correction code variable and transmit the transmission speed information including the transmission speed within the transmission band. A variable rate coding system for decoding based on information of a transmission rate in a transmission band of a signal, wherein a mobile terminal controls a transmission output control function by voice to interrupt a signal in a downlink transmission band. Changes the combination of the number of bits of the audio signal and the number of bits of the error correction code to be transmitted to the base station according to the transmission power control information indicating the state of the uplink quality, and the signal in the downlink transmission band is interrupted. If not, the signal generated based on the uplink quality signal measured at the base station is transmitted using the downlink to the mobile terminal, and the number of bits of the audio signal transmitted to the base station by the signal. And the combination of the number of bits of the error correction code,
When the signal in the upstream transmission band is interrupted by the control of the transmission output control function by voice, the number of bits and the error correction code of the voice signal to be transmitted to the mobile terminal according to the transmission power control information indicating the state of the downlink quality. When the signal in the upstream transmission band is not interrupted by changing the combination of the number of bits of
A combination of the number of bits of an audio signal and the number of bits of an error correction code to be transmitted to the mobile terminal by a downlink quality signal measured by the mobile terminal and transmitted using the uplink to the base station. In addition, even if a signal in a transmission band is interrupted, encoding can be performed at an appropriate speed.

First, the configuration of the variable rate coding system according to the present invention will be described with reference to FIG. FIG. 1 is a configuration block diagram of a variable rate coding system according to the present invention. Parts having the same configuration as in FIG. 2 will be described with the same reference numerals.

The variable rate coding system of the present invention (this system) has the same basic configuration as that of the conventional variable rate coding system, and includes a base station 1 for bidirectional voice transmission and reception and a mobile terminal 2. The mobile station 2 is wirelessly connected via a downlink from the base station 1 to the mobile terminal 2 and an uplink from the mobile terminal 2 to the base station 1.

The base station 1 of the present invention includes a speech coder 11, a downlink speed control unit 12, a transmission line coder 13, and an uplink speed control unit 14 as the same parts as the conventional base station 1 '. , A baseband processing unit 15, a radio unit 16, a transmission path decoder 17, and a speech decoder 18, and a downlink quality selection unit 19 is provided as a characteristic part of the present invention. The mobile terminal 2 according to the present invention includes a radio unit 21, a baseband processing unit 22 ', a transmission line decoder 23, a speech decoder 24, An uplink control selection unit 27 is provided as a characteristic part of the present invention.

Next, each unit of the variable rate coding system according to the present invention will be described. First, each unit in the base station 1 will be described. The audio encoder 11 compresses and encodes an audio signal at a speed adapted to the line quality. Specifically,
The speech encoder 11 receives a speech signal, compresses and encodes the speech signal at a speed specified by a downstream speed control signal input from the outside, and outputs a coded speech. Here, in the downlink speed control signal, an appropriate combination of the number of bits of the audio signal and the number of bits of the error correction code in the downlink is determined in accordance with the downlink quality measured by the mobile terminal 2,
This is output as a down speed control signal.

The transmission line encoder 13 performs transmission line encoding of the coded voice and information indicating the adapted speed at a speed adapted to the channel quality. Specifically, the transmission path encoder 13
Is to input coded voice and perform transmission path encoding at a rate specified by the above-described downlink rate control signal input from the outside. At this time, the downlink rate required when decoding is performed on the receiving side A control signal, and an uplink speed control signal for designating the uplink speed are also input from outside, and the audio data and the uplink,
It generates and outputs an in-band signal (encoded signal) including a downstream speed control signal. Here, an appropriate combination of the number of bits of the audio signal and the number of bits of the error correction code in the uplink is determined according to the uplink quality measured by the base station 1 and output as the uplink speed control signal. It was done.

As in the conventional baseband processing section 15 ', the baseband processing section 15 has a function of a transmitting side, which receives a coded signal to be transmitted, modulates the signal, and outputs a baseband signal. Has a function of receiving a baseband signal, demodulating the signal, and outputting a coded signal. Further, as a function on the receiving side, baseband processing section 15 checks uplink quality, calculates information indicating channel quality, and outputs the information as an uplink quality signal. Information indicating the line quality is the same as in the related art.

Further, as a characteristic part of the baseband processing unit 15 of the present invention, it is determined whether or not the in-band reception signal is disconnected by the VOX control. Is output (reception disconnection report signal). Further, the baseband processing unit 15 of the present invention includes:
Transmission power control information used in the CDMA wireless system is extracted from the received baseband signal and output.

Here, the transmission power control information is
This is essential information for solving a near-far problem in a CDMA wireless system, and is used for transmitter transmission power control information (TxTPC:
Tx Transmission Power Control). This TxTPC is information for controlling the transmission power from the base station 1 according to the result of measuring the downlink channel quality by comparing the SIR and the reference SIR in the mobile terminal 2. For example, when the channel quality is poor, This is information for controlling to increase the transmission power and decrease the transmission power when the channel quality is good, and is transmitted from the mobile terminal 2 to the base station 1. Since the transmission power control information is transmitted in a portion other than the user information (in-band) such as encoding information, the transmission power control information is not affected by the VOX control. As described above, this transmission power control information can be used instead because it is information having a high correlation with the downlink quality signal.

The radio section 16 receives a baseband signal as a function on the transmitting side, radiates the signal into space as a radio signal, and receives a radio signal from space and converts it into a baseband signal as a function on the receiving side. And output it.

The transmission path decoder 17 performs transmission path decoding of the received coded signal using the coding speed adapted on the transmission side. Specifically, the transmission path decoder 17 inputs the received encoded signal, first extracts and outputs the received uplink speed control signal incorporated in the encoded signal, and outputs the uplink speed control signal from the extracted uplink speed control signal. Then, it determines at what speed the received encoded speech signal is encoded on the transmitting side. Then, transmission path decoding is performed according to the determined encoding speed, and the received encoded voice from the mobile terminal 2 and the downlink quality signal incorporated in the mobile terminal 2 are output.

The speech decoder 18 decodes the received coded speech at a coding rate adapted on the transmission side. Specifically, the speech decoder 18
The received upstream speed control signal extracted in step (1) is input, the input coded voice is expanded at a speed based on the upstream speed control signal, voice decoded, and a decoded voice is output.

The downlink speed control unit 12 determines a coding rate adapted to the downlink in accordance with information indicating the quality of the downlink input from the outside, and outputs a downlink speed control signal for controlling the coding rate of the downlink. Generate and output. Specifically, the downlink speed control unit 12 inputs information indicating the quality of the downlink from the outside, and according to the quality, increases the bit allocation for voice when the channel quality is good, and increases the bit allocation for the voice when the channel quality is poor. And generates and outputs a downlink speed control signal for performing control to increase the bit allocation for error correction.
As a method of determining the coding rate, information on bit allocation with respect to the line quality is stored as a mode in software or on a memory in a table or the like in advance, and the mode associated with the input line quality is determined as the coding rate. However, the method is not limited to this. Also,
While the conventional downlink speed control unit 12 inputs the downlink quality signal from the transmission path decoder 17 as information indicating the downlink quality, the downlink speed control unit 12 of the present invention will be described later. The difference is that a downlink quality signal selected from the downlink quality selection unit 19 is input as information indicating downlink quality, and a downlink speed control signal is generated according to the quality.

The uplink rate control section 14 determines an encoding rate adapted to the uplink in accordance with information indicating the quality of the uplink inputted from the outside, and outputs an uplink rate control signal for controlling the encoding rate of the uplink. Generate and output. Specifically, in the uplink speed control unit 14, the baseband processing unit 1
5, an uplink quality signal indicating the quality of the uplink is input, and according to the quality, the bit allocation for voice is increased when the line quality is good, and the bit allocation for error correction is increased when the line quality is bad. And generates and outputs an upstream speed control signal for performing control to increase the speed. The method of determining the coding speed is the same as that of the downlink speed control unit 12.

The downlink quality selecting section 19, which is a feature of the present invention, selects information indicating downlink quality output to the downlink speed control section 12. Specifically, the downlink quality selecting section 19 The downlink quality signal from the channel decoder 17, the transmission power control information from the baseband processing unit 15, and the reception disconnection report signal indicating the radio signal reception disconnection from the baseband processing unit 15 are input, and the reception disconnection report is made. According to the state of the signal, either a downlink quality signal or transmission power control information is selected and output. That is, when the reception interruption report signal is not reception interruption, that is, when the uplink is transmitting voice, the downlink quality signal from the transmission path decoder 17 incorporated in the reception signal is used as information indicating the downlink quality. It is output to the downlink speed control unit 12 as a (selected downlink quality signal), and in the case of reception interruption, the transmission power control information from the baseband processing unit 15 is replaced with information indicating downlink quality (the selected downlink quality). The signal is output to the downstream speed control unit 12 as a line quality signal). It should be noted that the transmission power control information from the baseband processing unit 15 may be always captured, or may be captured only when reception is stopped.

Next, each unit in the mobile terminal 2 of the variable rate coding system according to the present invention will be described. The wireless unit 21
Similar to the radio unit 16 of the base station 1, the functions on the transmitting side include:
It receives a baseband signal, radiates it to space as a wireless signal, and, as a function of the receiving side, receives a wireless signal from space, converts it to a baseband signal, and outputs it.

As in the conventional baseband processing section 22 ', the baseband processing section 22 has a transmitting side function of inputting a coded signal to be transmitted, modulating the coded signal, outputting a baseband signal, and outputting the baseband signal. Has a function of receiving a baseband signal, demodulating the signal, and outputting a coded signal. Further, as a function on the receiving side, baseband processing section 22 checks downlink quality, calculates information indicating channel quality, and outputs the information as a downlink quality signal. Information indicating the line quality is the same as in the related art.

Further, as a characteristic part of the baseband processing unit 22 of the present invention, it is determined whether or not the in-band reception signal is disconnected by VOX control. Is output (reception disconnection report signal). Further, the baseband processing unit 22 of the present invention includes:
Transmission power control information used in the CDMA wireless system is extracted from the received baseband signal and output.

Here, the transmission power control information is
This is essential information for solving a near-far problem in a CDMA wireless system, and is used for receiver transmission power control information (RxTPC:
Rx Transmission Power Control). This RxTPC is information for controlling the transmission power from the mobile terminal 2 side according to the result of measuring the uplink quality in the base station 1. For example, when the channel quality is poor, the transmission power is increased, Is good, is information for controlling transmission power to be reduced, and is transmitted from the base station 1 to the mobile terminal 2. Since this transmission power control information is transmitted in a portion other than the user information (in-band) such as coding information, VOX
It is not affected by control. As explained above,
Since this transmission power control information is very similar to the uplink speed control signal, it can be used instead.

The transmission path decoder 23 performs transmission path decoding on the coded signal received at the coding speed adapted on the transmission side. Specifically, the transmission path decoder 23 inputs the received encoded signal, first extracts and outputs the received downlink speed control signal incorporated in the encoded signal, and outputs the downlink speed control signal from the extracted downlink speed control signal. Then, it determines at what speed the received encoded speech signal is encoded on the transmitting side. Then, transmission path decoding is performed according to the determined encoding speed, and the received encoded voice from the base station 1 and the uplink speed control signal incorporated in the base station 1 are output.

The speech decoder 24 is a conventional speech decoder 24
In the same manner as described above, the received coded voice is voice-decoded at the coding speed adapted on the transmission side. Specifically, the audio decoder 24 inputs the received downlink speed control signal extracted by the transmission line decoder 23, and expands the input coded audio at a speed based on the externally input downlink speed control signal. To decode the speech and output the decoded speech.

The speech encoder 25 is a conventional speech encoder 25.
In the same manner as described above, the audio signal is compression-coded at a speed adapted to the line quality. Specifically, the speech encoder 2
Numeral 5 is for inputting an audio signal, compression-encoding it at a speed designated by an externally input uplink speed control signal, and outputting an encoded audio.

The transmission path encoder 26 is a conventional speech encoder 2
As in the case of No. 5, the encoded voice and information indicating the adapted speed are channel-encoded at a speed adapted to the line quality. Specifically, the transmission path encoder 26 receives the coded speech and performs transmission path encoding at a rate specified by an externally input uplink rate control signal. A required uplink speed control signal and a downlink quality signal which is information indicating downlink quality are also input from the outside, and an in-band signal (encoded signal) including voice data, an uplink speed control signal, and a downlink quality signal Is generated and output.

Although the conventional speech encoder 25 and transmission path encoder 26 input the uplink speed control signal from the transmission path decoder 23, the speech encoder 25 and transmission path encoder 26 of the present invention use This is different from the related art in that the uplink speed control signal selected by the uplink control selection unit 27 is input, encoded, and transmitted.

The uplink control selector 27, which is a feature of the present invention, selects information for controlling the uplink speed supplied to the speech encoder 25 and the transmission channel encoder 26.
Specifically, the uplink control selection unit 27 includes the transmission line decoder 23
, The transmission power control information from the baseband processing unit 22, and the reception disconnection report signal indicating that the radio signal has been disconnected from the baseband processing unit 22. Accordingly, either the uplink speed control signal or the transmission power control information is selected and supplied to the speech encoder 25 and the transmission path encoder 26. In other words, when the reception interruption report signal is not reception interruption, that is, when the downlink is transmitting in-band audio, the uplink speed control signal from the transmission line decoder 23 incorporated in the reception signal is transmitted to the uplink line speed. Coder 25 as information (selected uplink speed control information) for controlling
And in the case of reception interruption, the transmission power control information from the baseband processing unit 22 is used as information for controlling the uplink speed (selected uplink speed control information). 25 and transmission path encoder 2
6 is output. It should be noted that the transmission power control information from the baseband processing unit 22 may be always fetched, or may be fetched only when reception is stopped.

Next, the operation of the variable speed speech coding system of the present invention will be described with reference to FIG. First, a downlink signal will be described. On the base station 1 side, the voice signal a input from the network side is compression-coded by the voice encoder 11 at the adaptive speed specified by the downlink speed control signal c from the downlink speed control unit 12, and Output as b. Then, the coded voice b is transmitted to the transmission line encoder 13 by the downlink speed control signal c from the downlink speed controller 12.
At the adaptive speed specified by, transmission line coding is performed,
Further, a downlink speed control signal c required for decoding on the receiving side, and an uplink speed control unit 1 for specifying an uplink speed.
4, and the in-band signal (output signal f) is generated and output.

At this time, the downlink speed control signal c is determined in the downlink speed control unit 12 according to the downlink quality signal C selected from the downlink quality selection unit 19, and is output. Things. The uplink speed control signal d is output by the uplink speed control unit 14 in which the adaptive speed in the uplink is determined according to the uplink quality signal e from the baseband processing unit 15.

The output signal f is modulated by the baseband processing unit 15 to become a baseband signal g, further converted by the radio unit 16 into a radio signal h, radiated into space, and transmitted on the downlink. .

Then, on the mobile terminal 2 side, the radio signal h is received by the radio unit 21 and converted into a baseband signal i, demodulated by the baseband processing unit 22, and an encoded signal j is output. At this time, the baseband processing unit 2
In 2, the downlink quality is checked and a downlink quality signal q is output. Further, the baseband processing unit 22 determines whether or not the received signal is disconnected from the baseband signal i. If the received signal is determined to be disconnected, the reception disconnection report signal D is output, and the received baseband signal To CDM
Transmission power control information E used in the wireless system A is extracted and output.

The coded signal j output from the baseband processing unit 22 is input to a transmission path decoder 23,
The transmission path decoder 23 extracts and outputs the downlink speed control signal k from the coded signal j, and decodes the transmission path at a speed according to the downlink speed control signal k, and outputs the encoded voice 1 and the uplink speed. The control signal m is output. Then, the coded voice 1 is voice-decoded by the voice decoder 24 at a speed according to the downstream speed control signal k from the transmission line decoder 23,
A decoded voice n is output.

Next, an uplink signal will be described. In the downlink operation described above, the baseband processing unit 22
A transmission disconnection report signal D indicating whether or not the received signal output from the PDU is disconnected, and transmission power control information E are input to the uplink control selecting section 27, and furthermore, the transmission path decoder 23
The uplink speed control signal m output from is input to the uplink control selection unit 27. Then, the uplink control selection unit 27
When the reception is interrupted, the transmission power control information E is selected and output as the selected uplink speed control signal F. When the reception is not interrupted, the uplink speed control signal m is selected and the uplink speed control signal m is selected. Is output as

On the mobile terminal 2 side, the input audio signal 0
Is the uplink control selection unit 27 in the speech encoder 25.
At the adaptive speed specified by the selected upstream speed control signal F, and is output as a coded voice p. The coded voice p is subjected to transmission line encoding at an adaptive speed designated by an uplink speed control signal F selected from an uplink control selection unit 27 in a transmission line encoder 26, and further received. The selected uplink speed control signal F necessary for decoding on the side, and a downlink quality signal q from the baseband processing unit 22 indicating the quality of the downlink.
At the same time, an in-band signal (output signal r) is generated and output.

The output signal r is modulated by the baseband processing unit 22 to become a baseband signal s, further converted into a radio signal t by the radio unit 21, radiated to the space, and transmitted on the uplink. .

In the base station 1, the radio signal t is received by the radio section 16, converted into a baseband signal u, demodulated by the baseband processing section 15, and an encoded signal v is output. At this time, the baseband processing unit 15 checks the uplink quality and outputs an uplink quality signal e. Further, the baseband processing unit 15 determines whether the received signal is disconnected from the baseband signal u, and when it is determined that the received signal is disconnected, a reception disconnection report signal A is output and the received baseband signal , Transmission power control information B used in the CDMA wireless system is extracted and output. The encoded signal v output from the baseband processing unit 15 is
7, the transmission path decoder 17 extracts and outputs the upstream speed control signal w from the coded signal v, and decodes the transmission path at a speed according to the upstream speed control signal w. A voice x and a downlink quality signal y are output. The coded voice x is voice-decoded by the voice decoder 18 at a speed according to the uplink speed control signal w from the transmission path decoder 17, and the decoded voice z is output to the network side.

Here, the downlink quality signal y from the transmission path decoder 17 is input to the downlink quality selection section 19, and the downlink quality selection section 19 receives the signal (uplink) from the baseband processing section 15. ) Is a disconnection report signal A indicating whether or not the transmission has been disconnected, and the transmission power control information B, the transmission power control information B when the reception is disconnected is
As the selected downlink quality signal C, the downlink speed control unit 1
2 and when the reception is not interrupted, the downlink quality signal y
Is output to the downlink speed control unit 12 as the selected downlink quality signal C.

Then, the downlink speed controller 12 determines the adaptive speed in the downlink according to the downlink quality signal C selected from the downlink quality selector 19, outputs the downlink speed control signal c, and outputs It is used by the encoder 11 and the transmission line encoder 13.

The uplink quality signal e from the baseband processing unit 15 is input to an uplink speed control unit 14, and the uplink speed control unit 14 generates an uplink speed control signal d indicating an adaptive speed according to the quality. The transmission line coder 13 generates the generated information, and performs transmission path coding together with voice data as speed information adapted to the line quality in the uplink from the mobile terminal 2 to the base station 1, and transmits the information on the downlink. .

As described in detail above, in the variable rate coding system of the present invention, when the line is being transmitted in the transmission state, the line quality signal using the in-band signal And transmission of a rate control signal (in-band signaling), a plurality of different combinations of bit allocations of voice coding and error correction coding, which are characteristics of the variable rate coding system, are set, and an error state of the transmission path (line Quality), the encoder (11, 13, 25,
26) can adaptively switch this bit allocation.

Further, in the variable rate coding system of the present invention, when the voice is not transmitted in the receiving state due to the VOX control and the in-band signaling is interrupted, the transmission power which is a parameter specific to the CDMA radio system is used. By using the control information instead,
Encoders (11, 13, 25, 2) according to the error state (line quality) of the transmission path, which is a feature of the variable rate coding system.
6) adaptively switches the bit allocation between the voice coding and the error correction coding, and makes it possible to switch the transmission speed of voice data.

In the variable speed coding system described with reference to FIG. 1, the downlink speed control unit 12 and the uplink speed control unit are means for determining an appropriate speed from signals indicating the channel quality of the uplink and the downlink. 14 are arranged in the base station 1, but the uplink speed control unit 14 that determines an appropriate speed from a signal indicating the channel quality of the uplink is provided to the mobile terminal 2.
It may be arranged on the side. However, in this case, the uplink quality signal measured by the baseband processing unit 15 of the base station 1 is directly transmitted to the mobile terminal 2 on the downlink, and an uplink speed control signal is generated in the mobile terminal 2. Therefore, the configuration of the mobile terminal 2 aiming at reduction in size and weight is not very suitable.

Further, the variable rate coding system of the present invention can be applied to not only a single system but also a multi-band system and a software defined radio.

According to the variable rate coding system of the embodiment of the present invention, mobile terminal 2 receives the downlink signal from base station 1 to mobile terminal 2 by the reception disconnection report signal output from baseband processing section 22. The disconnection of the line in-band signal is determined by the uplink control selection unit 27, and when the downlink disconnection is detected, the uplink speed control signal from the base station 1 is not transmitted. 2
7 selects the transmission power control signal from the baseband processing unit 22 and supplies it to the voice encoder 25 and the transmission line encoder 26 as an uplink speed control signal, so that the VOX control interrupts the downlink inband signal. Even if
There is an effect that voice data from the mobile terminal 2 can be transmitted to the base station 1 at an appropriate speed adapted to the uplink quality from the mobile terminal 2 to the base station 1.

If the downlink in-band signal is not interrupted, the uplink speed control signal from base station 1 is transmitted as an in-band signal as in the conventional case, so that uplink control selecting section 27 Since the uplink rate control signal from the transmission path decoder 23 is selected and supplied to the speech encoder 25 and the transmission path encoder 26 as the uplink rate control signal, the AMR
Thus, there is an effect that voice data from the mobile terminal 2 can be transmitted to the base station 1 at an appropriate speed adapted to the uplink quality from the mobile terminal 2 to the base station 1.

Further, according to the variable rate coding system of the embodiment of the present invention, base station 1 uses the reception disconnection report signal output from baseband processing section 15 to
The disconnection of the uplink in-band signal from the mobile terminal 2 to the base station 1 is determined by the downlink quality selection unit 19, and when the uplink disconnection is detected, the downlink quality signal from the mobile terminal 2 is transmitted. Since the transmission quality control signal has not been transmitted, the downlink quality selection section 19 selects the transmission power control signal from the baseband processing section 15 and supplies it to the downlink speed control section 12 as a downlink quality signal. Even if the in-band signal is lost, the base station 1
Thus, there is an effect that voice data from the base station 1 can be transmitted to the mobile terminal 2 at an appropriate speed adapted to the downlink quality from the mobile terminal 2 to the mobile terminal 2.

[0086] When the uplink in-band signal is not interrupted, the downlink quality signal from the mobile terminal 2 is transmitted as an in-band signal as in the conventional case.
Since the downlink quality selecting section 19 selects the downlink quality signal from the transmission path decoder 17 and supplies it to the downlink speed control section 12, the base station 1 transmits the mobile terminal 2 based on the AMR.
It is possible to transmit the voice data from the base station 1 to the mobile terminal 2 at an appropriate speed adapted to the downlink quality to the mobile terminal 2.

[0087]

According to the present invention, when transmitting a voice signal between a base station and a mobile terminal, a plurality of combinations having different bit allocations for voice coding and error correction coding are prepared and transmitted. A variable rate coding system that determines the state of line quality using signals in the band, and adaptively switches and transmits the allocation of these bits according to the state of the line quality to transmit the signal. In the case of interruption, transmission is performed by switching the allocation of these bits according to transmission power control information that correlates to the state of the line quality. There is an effect that can be performed.

Further, according to the present invention, even when a signal in a transmission band is not interrupted, the allocation of bits for speech coding and error correction coding is controlled by transmission power control information correlated with the state of channel quality. Since the variable rate coding system is adapted to switch and transmit adaptively, there is an effect of not being affected by interruption of a signal in a transmission band.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a variable-rate speech encoding system according to the present invention.

FIG. 2 is a configuration block diagram of a conventional variable-rate speech encoding system.

[Explanation of symbols]

1, 1 ': base station, 2, 2': mobile terminal, 11: voice coder, 12: downlink speed control unit, 13: transmission line coder, 14: uplink speed control unit, 15: baseband processing unit, 16: Radio section, 17: Transmission path decoder, 1
8 Voice decoder 19 Downlink quality selection unit 21
... a radio section, 22 ... a baseband processing section, 23 ... a transmission path decoder, 24 ... a speech decoder, 25 ... a speech encoder,
26: transmission path encoder, 27: uplink control selection section

Claims (4)

[Claims] When transmitting a voice signal between a base station and a mobile terminal, a plurality of combinations having different bit allocations between voice coding and error correction coding are prepared, and a signal within a transmission band is used. A variable rate coding system that determines the state of the line quality and determines the state of the line quality and adaptively switches the bit allocation according to the state of the line and transmits the signal.If the signal in the transmission band is interrupted, A variable rate coding system, wherein the bit allocation is switched and transmitted according to transmission power control information correlated with a state of channel quality. 2. When transmitting a voice signal between a base station and a mobile terminal, the transmitting side adaptively changes the combination of the number of bits of the voice signal and the number of bits of the error correction code according to the state of the line quality. To make the transmission speed of the audio signal and the transmission speed of the error correction code variable and transmit the transmission speed information in the transmission band, and the receiving side adjusts the transmission speed in the transmission band of the received signal. A variable rate encoding system for decoding based on information, wherein the mobile terminal has a bit number and an error correction code of an audio signal to be transmitted to the base station according to transmission power control information indicating a state of uplink quality. In the base station, the combination of the number of bits of the voice signal and the number of bits of the error correction code to be transmitted to the mobile terminal according to the transmission power control information indicating the state of the downlink quality Variable rate coding system characterized by varying the Align. 3. When transmitting a voice signal between a base station and a mobile terminal, the transmitting side adaptively changes the combination of the number of bits of the voice signal and the number of bits of the error correction code according to the state of the line quality. To make the transmission speed of the audio signal and the transmission speed of the error correction code variable and transmit the transmission speed information in the transmission band, and the receiving side adjusts the transmission speed in the transmission band of the received signal. A variable-rate encoding system for decoding based on information, wherein the mobile terminal controls a transmission output control function by voice, and when a signal in a downlink transmission band is interrupted, indicates a state of uplink channel quality. Changing the combination of the number of bits of the audio signal and the number of bits of the error correction code to be transmitted to the base station according to the transmission power control information, when the signal in the downlink transmission band is not interrupted, A signal generated based on the determined uplink quality signal is transmitted using the downlink to the mobile terminal, and the number of bits of the audio signal and the bit of the error correction code transmitted to the base station by the signal. In the base station, when the signal in the uplink transmission band is interrupted by the control of the transmission output control function by voice, the base station moves the mobile station according to the transmission power control information indicating the state of the downlink quality. Changing the combination of the number of bits of the voice signal and the number of bits of the error correction code to be transmitted to the terminal, when the signal in the uplink transmission band is not interrupted, measured by the mobile terminal, the uplink to the base station Changing a combination of the number of bits of an audio signal and the number of bits of an error correction code to be transmitted to the mobile terminal according to a downlink quality signal transmitted using the method. Variable rate coding system. 4. A system for transmitting a voice signal between a base station and a mobile terminal, wherein the base station and the mobile terminal include a voice coder for compressing and coding voice at various specified rates. A transmission path for performing transmission path encoding on the compression-encoded coded voice and control information necessary for decoding the coded voice in accordance with the specified speed, and outputting a coded signal; An encoder, a transmission path decoder that performs transmission path decoding on the coded signal according to the control information arranged in the transmission band, and outputs coded voices of various rates; and the various rates. A speech decoder that expands the encoded speech and outputs a decoded speech, measured by the mobile terminal, and transmitted by a downlink quality signal transmitted from the mobile terminal to the base station using an uplink. A down speed controller that determines the down speed A signal generated based on an uplink quality signal measured by the base station is transmitted using a downlink from the base station to the mobile terminal, and an uplink speed control unit that determines an uplink speed based on the signal. A variable rate coding system having a function of controlling a transmission output control function by voice, and when a signal in a downlink transmission band is interrupted, a signal for determining an uplink rate is determined from transmission power control information in the mobile terminal. An uplink control selection unit to be generated is provided in the mobile terminal, and under control of the transmission output control function, when a signal in an uplink transmission band is interrupted, a downlink speed is determined from transmission power control information in the base station. A variable rate coding system, wherein a downlink quality selection unit for generating a signal is provided in the base station.