JPH08316901A - Transmitter and receiver - Google Patents

Abstract

PURPOSE: To improve the speech quality without interrupting the talking voices by detecting the error state of a prescribed pattern when the absence of control data is detected out of the received prescribed data included in a single slot. CONSTITUTION: An error is detected out of the data received by a slot by an error detection parity CRC in a reception processing mode. If the data on a slow attendant channel SA are not available in a single slot, the voice data are muted based on the reception state of a fixed pattern that is transmitted in the section of the channel SA. Otherwise, it is possible to decide whether the output processing should be carried out with no mute processing, so that the mute processing can be minimized. Then the voice data are outputted as they are after decision of occurrence of no abnormality of these data as long as a small number of errors are decided even for the voice whose error is detected by the parity CRC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus and a receiving apparatus suitable for application to, for example, what is called a digital cordless telephone for transmitting and receiving burst data having a slot structure.

[0002]

2. Description of the Related Art A digital cordless telephone system is constructed, for example, as shown in FIG. In FIG. 9, reference numeral 1 denotes a base unit that serves as a base station, and the base unit 1 is connected to a telephone line and includes an antenna 1a for communicating with a handset. A plurality of (three in this case) slaves capable of communicating with the master 1 are prepared. That is, the slaves 2, 3 and 4 are prepared, the antennas 2a, 3a and 4a are attached to the slaves 2, 3 and 4, respectively, and the antenna 1a of the master 1 and the antennas of the slaves 2, 3 and 4 are attached. 2a, 3a, 4
Wireless transmission is performed with a.

When a call is made with each of the slave units 2, 3 and 4 to the master unit 1 (or the other party connected to the master unit 1 via a telephone line), a connection control signal of a predetermined format is transmitted to the master unit 1.
Then, the voice data converted into digital data is transmitted to the base unit 1 in a time division manner with the base unit 1 to make a call.

In such a digital cordless telephone device, a TDMA method (time division multiple access method) is adopted as a radio access method, and a TDMA / TDD method adopting a TDD method (time division duplex method) is adopted as a transmission method. is there. This TDMA / TDD system will be described with reference to FIG. 10. A of FIG. 10 shows the arrangement of communication slots. One transmission channel has 5 msec as one frame, and this one frame is divided into eight. One slot has 625 μsec. Then, the first four slots in one frame are designated as transmission slots T1, T2, T3, T4, and the latter four slots are designated as reception slots R1, R2, R.
3 and R4. This frame structure is repeated every 5 ms.

If communication is performed simultaneously between one master unit and two slave units 1 and 2 using one transmission channel, for example, the master unit (B in FIG. 10) is used. With respect to the slave unit 1 (C in FIG. 10), transmission from the master unit to the slave unit 1 is performed using the transmission slot T2, and transmission from the slave unit 1 to the master unit is performed using the reception slot R2. To do. Further, between the master unit and the slave unit 2 (D in FIG. 10), transmission from the master unit to the slave unit 2 is performed using the transmission slot T3, and the reception slot R3.
Is used to transmit from the child device 2 to the parent device. In this way, when four slots are prepared for the transmission slot and four slots for one frame, one master unit uses one transmission channel to simultaneously communicate with up to four slave units. (However, since the transmission slot T1 and the reception slot R1 are used for transmission of control data, they are normally limited to simultaneous communication of up to three slave units).

[0006] The frequency band prepared for the cordless telephone is efficiently used by performing the communication between the master unit and the slave unit by such a communication method.

[0007]

By the way, CRC (Cyclic Redun) is included in the data of the slot configuration transmitted in such a digital cordless telephone system.
An error detection code called a "dank check" code is added so that when each slot is received, an error such as voice data in the slot or control data accompanying the voice is detected. When an error is detected with this error detection code, mute processing is performed to put the voice data transmitted in this slot into a silent state, and abnormal noise is prevented from being output due to the erroneously transmitted voice data. I am doing it.

Here, the error occurrence state of the transmitted voice data may be a slight error of about 1 to 2 bits or a burst error in which bit errors occur continuously for a predetermined period. However, with the error correction code used in the standard of the current digital cordless telephone system, it is impossible to determine how many errors are present.
Even in the case of a slight error of about 2 bits, the audio data of all 1 slot (that is, 5 ms of audio) was always muted. Therefore, when a reception error occurs in the voice data, the voice that is temporarily output is interrupted, and the quality of the call voice is degraded.

In view of the above points, the present invention has an object to improve the quality of voice when a voice communication is carried out by using a transmitter and a receiver of this kind to make a call.

[0010]

In order to solve this problem, the transmitting apparatus of the present invention uses a code indicating the absence of control data in predetermined data in one slot when there is no data to be transmitted as control data. In addition to transmitting data, data of a predetermined pattern determined in advance is transmitted as control data.

Further, in the receiving apparatus of the present invention, when the absence of control data is detected in the received predetermined data in one slot, when the error of the voice data is detected by the error detection code, the control data is transmitted in the transmission section. The error state of the arranged data of a predetermined pattern is detected.

[0012]

According to the present invention, when there is no control data attached to the voice data and an error of the voice data is detected by the error detection code added to the voice data and transmitted, the control data is transmitted in the control data transmission section. The error state of the received data can be estimated based on the detected state of the predetermined pattern of data, and various processing based on this estimated state becomes possible.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

The present embodiment is applied to a digital cordless telephone apparatus in which burst data having a slot structure is transmitted and received intermittently in the TDMA communication system. First, the structure of the master unit is shown in FIG. The wireless unit 12 receives and processes the data received from the slave unit by the antenna 11, and the modem unit 1
3 and demodulates the received data. Then, the demodulated received data is supplied to the communication control unit 14. This communication control unit 14 discriminates the data transmitted intermittently in the slot configuration, extracts various data such as voice data and control data inserted in each slot, and AD the voice data.
The communication control is performed based on various control data while being supplied to the PCM codec unit 15.

Then, the voice data supplied from the communication control unit 14 to the ADPCM codec unit 15 is converted into an analog voice signal, the analog voice signal is supplied to the line interface unit 16, and the analog telephone line connection terminal 17 is provided.
Send to the side.

An analog voice signal obtained from the analog telephone line connection terminal 17 side is supplied to the ADPCM codec unit 15 via the line interface unit 16,
Digital data of DPCM (adaptive differential pulse code modulation) is supplied to the communication control unit 14 to be slot configuration data. In this case, synchronization data and control data are added to each slot.

Then, the slot configuration data created by the communication control unit 14 is supplied to the modulation / demodulation unit 13 at a predetermined transmission timing, and the modulation / demodulation unit 13 modulates the data for transmission. Then, the modulated data is wirelessly transmitted from the antenna 11 connected to the wireless unit 12.

Further, the handset 18 is directly connected to the line interface section 16 so that the handset 18 can communicate with the outside line side through the analog telephone line connection terminal 17 and can be connected to the ADPCM codec section 15 side so that a child can be connected. It is possible to make extension calls with the machine. Further, the key input unit 19 is connected to the line interface unit 16 so that various controls such as transmission to an outside line can be performed.

Next, FIG. 2 shows the structure of the slave unit. The structure of the wireless communication device is basically the same as that of the master unit, and the data received by the antenna 21 from the master unit or another slave unit is received. Is received by the wireless unit 22, and supplied to the modulation / demodulation unit 23 to demodulate the received data. Then, the demodulated received data is supplied to the communication control unit 24 to discriminate the data of the slot configuration, the audio data in the received data is supplied to the ADPCM codec unit 25 as an analog audio signal, and the analog audio signal is supplied to the speaker 26. To output from.

The voice signal picked up by the microphone 27 is AD
It is supplied to the PCM codec section 25 to be ADPCM digital data, and this digital data is sent to the communication control section 24.
Supply to. Then, the communication control unit 24 makes the data of the slot configuration, supplies the data of the slot configuration to the modulation / demodulation unit 23 at a predetermined timing, modulates the data for transmission, and the modulated data is connected to the radio unit 22 by an antenna. 21
Wireless transmission from.

Further, the key input unit 28 is connected to the ADPCM codec unit 2 via the man-machine interface unit 29.
5 and the operation information of the key input unit 28 is supplied to the communication control unit 24 side. Further, the display unit 30 is connected to the man-machine interface unit 29 so that the operating state and the like can be displayed.

Next, the structure of slot data used for transmitting voice data between the master unit and the slave unit in the cordless telephone system of this example will be described. The physical data defined by the digital cordless telephone system will be described below. The communication slot configuration is as shown in FIG. That is, 1 slot is 625
It is configured to transmit 240 bits in μ seconds, and ramp bits R (4 bits), start symbol SS (2 bits), preamble PR (6 bits), unique word UW (16 bits), channel identification code CI in order from the beginning. (4 bits), low speed associated channel SA
(16 bits), audio data TCH (160 bits),
An error detection parity CRC (16 bits) and a guard bit GB (16 bits: no data in this section) are arranged.

Here, 1 ms of 160-bit audio data TCH is provided with audio data of 5 msec.
The bit error detection parity CRC is an error detection code generated for the voice data TCH, the low-speed associated channel SA, and the channel identification code CI, and is a parity of generation polynomial = X ¹⁶ + X ¹² + X ⁵ +1. is there. When the voice data TCH and the error detection parity CRC are arranged in each slot, the scramble circuit scrambles and arranges them.

The unique word UW is synchronization data for synchronizing the slot data on the receiving side,
16-bit specific pattern data determined by the communication method of this system is transmitted.

As the low-speed associated channel SA, the allocated 16-bit period is used so that data having a low bit rate can be transmitted. This low-speed associated channel SA is for transmitting necessary communication control data even during a call such as call connection and disconnection.

In the present example, when the control data is not transmitted on the low speed associated channel SA, as shown in FIG.
As shown in FIG. 6, the data of a fixed pattern (for example, data of a pattern in which “1001” is repeated for 16 bits) different from the data pattern existing for transmitting the accompanying data on the channel SA is used as the channel identification code C.
A predetermined 4-bit data (for example, 4-bit data of "1110") indicating that there is no low-speed associated channel information is transmitted by I.

The burst data having the above slot structure is transmitted from the master unit and the slave unit of this example, and the receiving side processes it.

Next, the communication control units 14 and 24 of the master unit and the slave unit
Now, a process of generating burst data during transmission will be described. FIG. 5 is a diagram showing a configuration therefor.
The configuration is basically the same for any of the slave units. First, digital audio data of ADPCM (adaptive differential pulse code modulation) supplied from the ADPCM codec section 15 or 25 side is supplied from a terminal 41 to an audio data processing circuit 42, and the audio data is processed by this processing circuit 42 by 160 bits at a time. The audio data TCH is divided into.
Then, the 160-bit audio data TCH
It is supplied to the error detecting parity encoding circuit 43.

Further, the low speed associated channel SA output from the low speed associated channel generation circuit 44 and the channel type data CI output from the channel type data generation circuit 45.
And 16-bit fixed pattern data output from the fixed pattern generation circuit 46 are supplied to the error detection parity encoding circuit 43. In this case, the data content of the low speed associated channel SA output from the low speed associated channel generation circuit 44 is determined by the channel type data generation circuit 45, and when it is determined that there is no data, it indicates that there is no low speed associated channel information. The code channel type data CI is supplied to the error detection parity encoding circuit 43. The fixed pattern generation circuit 46 also determines the data content of the low speed associated channel SA output by the low speed associated channel generation circuit 44, and outputs 16-bit fixed pattern data only when it is determined that there is no data. Is done. The 16-bit fixed pattern data is data to be inserted in the section shown as the fixed pattern in the slot shown in FIG.

The error detecting parity coding circuit 4
In 3, the error detection parity CRC is generated for the supplied audio data TCH, channel type data CI, and low speed associated channel SA (or fixed pattern).
Then, the data to which the generated parity CRC is added is supplied to the scramble circuit 47, and the audio data TCH and the error detection parity CRC in the supplied data are scrambled and processed. The data (including the channel type data CI and the low speed associated channel SA) is supplied to the fixed pattern addition circuit 48.

Then, in the fixed pattern adding circuit 48,
The data having the same pattern (preamble, unique word, etc.) is always added to the data forming one slot, and each data forming one slot is shown in FIG.
Alternatively, the fixed pattern adding circuit 4 having the arrangement shown in FIG.
The output terminal 49 of 8 outputs burst data of 1 slot.

FIG. 6 is a flow chart showing the burst data generation process at the time of transmission performed as described above.
First, it is judged whether or not there is data of the low-speed associated channel (step 101). If there is data of the low-speed associated channel, the data SA of the corresponding low-speed associated channel is set to 1
Place it in the corresponding position in the slot (step 10
2). If there is no low speed associated channel data, a 16-bit fixed pattern output from the fixed pattern generation circuit 46 is added instead of the low speed associated channel data SA, and the channel type data CI is added.
Is set as the corresponding data (step 103).

Next, FIG. 7 shows a configuration for receiving and processing the burst data thus transmitted. This burst data reception processing is performed by the communication control units 14 and 24 of the master unit and the slave unit.
The basic configuration is the same for both the master unit and the slave unit. First, the received data demodulated by the modulator / demodulator 13 or 23 is supplied to the descramble circuit 52 via the terminal 51.

In the descramble circuit 52, the position where each data in one slot is arranged is determined based on the synchronous data such as a unique word, and the scramble applied to the voice data TCH and the parity CRC is released. Perform descramble processing. Then, the descrambled received data is supplied to the error detection circuit 53, and error detection processing is performed based on the error detection parity CRC added as the parity.

If no error is detected in the slot data at this time, the audio data TCH is supplied to the audio data processing circuit 54, and the processed audio data (A
Output terminal 5 for continuous DPCM digital audio data)
Get to 5. Further, the channel type data CI in this slot is supplied to the channel type discriminating circuit 56, the control corresponding to the discriminated channel type data CI is executed, and the low speed associated channel SA is supplied to the low speed associated channel discriminating circuit 58. The low speed associated channel SA is discriminated and the corresponding control is executed.

Then, the error detection circuit 53 detects an error in the data of the slot at this time, and the channel type determination circuit 56 indicates the existence of the low-speed associated channel SA by the channel type data CI added to this slot. When the data is discriminated, a command to put the audio data TCH at this time into the mute state, which is a silent state, is sent to the audio data processing circuit 54, and the low speed associated channel determination circuit 58 displays the contents of the low speed associated channel SA at this time. Ignore it.

Further, the data of the section of the low speed associated channel SA in the reception slot is supplied from the error detection circuit 53 to the fixed pattern error number determination circuit 57. In the error number discriminating circuit 57, the presence of an error is detected by the parity check in the error detecting circuit 53, and in the channel type data CI discriminated by the channel type discriminating circuit 56, the absence of the data of the low speed associated channel is detected. At this time, the number of data errors in the section of the low speed associated channel SA is determined. The determination processing in the error number determination circuit 57 at this time is as follows:
On the transmitting side, insert the data SA in this section instead of 1
The error number discriminating circuit 57 stores 6-bit fixed pattern data in advance, and compares the stored 16-bit fixed pattern data with the received data of the section of the low-speed associated channel SA. , How many bits are different (that is, how many bit reception errors have been made).

Then, the determined number of errors is E bits (E
Is any integer: eg less than 3 bits)
In the audio data processing circuit 54, the audio data TCH transmitted in the slot at this time is output-processed, and the output terminal 5
The processed voice data is output from 5. When the fixed pattern error number determination circuit 57 determines the number of errors, the low speed associated channel determination circuit 58 ignores the contents of the low speed associated channel SA at this time.

When the determined error number is equal to or more than E bits, the voice data processing circuit 54 is instructed to put the voice data TCH transmitted in the slot at this time into a mute state, which is a silent state. The low speed associated channel determination circuit 58 causes the contents of the low speed associated channel SA at this time to be ignored.

The burst data discrimination processing at the time of reception performed in this way is shown in the flowchart of FIG.
First, based on the error detection parity CRC, it is judged whether or not an error is detected in the data of this slot (step 111). Here, if no error is detected,
That is, when it is determined that there is no error, the audio data processing circuit 54 executes the audio data processing, and
The low speed associated channel determination circuit 58 determines the contents of the low speed associated channel SA (step 112).

If it is detected in step 111 that there is an error in the received data, it is judged whether or not the data indicating the existence of the low-speed associated channel is judged by the channel type judging circuit 56 (step 113). Here, when the data indicating the presence of the low-speed associated channel (actually, data other than the low-speed associated channel is not present) is discriminated, the audio data TCH at this time is muted.
The contents instructed on the low-speed associated channel SA are ignored (step 114).

When the channel type data indicating that there is no low speed associated channel is determined in step 113, the number of errors determined by the fixed pattern error number determination circuit 57 is less than the set threshold value E (for example, 3 bits). It is determined whether or not (step 115). Here, if it is not less than the threshold value E, the process proceeds to step 114, where the audio data TCH at this time is muted, and the content instructed by the low speed associated channel SA is ignored.

If it is determined in step 115 that the number of errors is less than the threshold value E, the audio data processing circuit 54 executes audio data processing, and
The contents of the low speed associated channel SA determined by the low speed associated channel determination circuit 58 are ignored (step 116).

When the error detection parity CRC detects an error in the received data of the slot at this time by performing the reception processing in this way, and there is no data of the low-speed associated channel in one slot at this time. It is possible to determine whether the audio data should be muted or output without being muted based on the reception state of the fixed pattern transmitted in the section of the low-speed associated channel SA. It can be reduced as much as possible. That is, in the case of the system of the present example in which one slot is transmitted in a relatively short time of about several hundreds of microseconds, it is estimated that the reception error occurrence state in each slot is almost the same,
When the number of bits for which a reception error is determined in a fixed pattern transmitted in the section of the low-speed associated channel SA is small (that is, when the reception error rate is low), the reception error rate of the audio data TCH transmitted subsequently is also set. It can be estimated to be low. Therefore, in such a case, even if the voice data has an error detected by the parity CRC, the number of errors is estimated to be small, and even if the voice data TCH is output as it is, it is output from the speaker or the like. The voice can be estimated to be a voice that is not so different from the original voice, and the output process is performed.

On the other hand, when the reception error rate determined based on the fixed pattern is high, it can be estimated that the reception error rate of the voice data TCH transmitted following the fixed pattern is also high, and if it is output as it is, the original error rate is obtained. It is determined that an abnormal sound different from the voice is likely to be output from the speaker or the like, and the mute processing of the voice data of 5 msec transmitted in this slot is performed.

By performing the mute processing determination as described above, even if an error in the audio data is detected by the error detection parity CRC, the audio can be output depending on the state, and the mute processing may be performed accordingly. As a result, the call voice is less likely to be interrupted by the temporary mute process.

The low-speed associated channel SA is used for call connection,
This is communication control data required during a call such as disconnection, the frequency of transmitting some data during a call is not so high, and a fixed pattern is likely to be transmitted in the section of the low-speed associated channel SA. Judgment based on the above configuration works effectively.

In this example, when there is data of the low-speed associated channel SA, only the mute process based on the error detection similar to the conventional one is performed. Therefore, the mute process based on the determination of the fixed pattern is performed. It is possible to maintain compatibility with conventional digital cordless telephones that do not perform. For example, when the master unit and the slave unit having the configuration of this example are used, a good call with less possibility of mute processing is performed, and this slave unit is called PHS (Personal Handy Phone System). When it is used as a terminal for a wireless telephone and communicates with a base station that does not have a function of transmitting a fixed pattern instead of the low-speed associated channel SA, the same communication processing as in the conventional case is performed.

In the above embodiment, the master unit of the cordless telephone has been described as a master unit installed by a general subscriber, but also in the case of a base station for wireless telephone called PHS,
The configuration for performing communication with the terminal device (slave device) is the same as that of the parent device for general subscribers, and the communication method is basically the same. In this PHS, the communication between the base station and the terminal device is performed. It goes without saying that the present invention can be applied to the case of performing communication. Further, the present invention can be applied to a communication device for transmitting and receiving burst data having a slot structure other than a digital cordless telephone and PHS.

Further, in the above-described embodiment, as the processing when the received voice data cannot be used, the voice of the corresponding section is temporarily muted, but the voice data before and after the voice data that cannot be used is changed. Other processing such as interpolation based on the above may be performed.

[0051]

According to the present invention, when there is no control data associated with the voice data and an error of the voice data is detected by the error detection code added to the voice data and transmitted, the control data transmission section It becomes possible to estimate the error state of the received data almost accurately based on the detected state of the data of the predetermined pattern arranged in the, and the accuracy of the data in processing the received data can be known. .

Since the accuracy of the received data can be estimated, it is possible to determine, based on the estimated state, whether the audio data should be output or muted. For example, if the estimated error state is an error with few bits, it is possible to output the audio data as it is, and only if it is determined that the error has many bits, the mute process is performed. Should be done. Therefore, the possibility that the call voice is interrupted by the mute processing is reduced, and the quality of the call voice can be kept good.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a base unit of a cordless telephone device to which an embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of a child device of a cordless telephone device to which an embodiment of the present invention is applied.

FIG. 3 is an explanatory diagram showing a configuration of one slot according to an embodiment.

FIG. 4 is an explanatory diagram showing a 1-slot configuration (when there is no low-speed associated channel) according to an embodiment.

FIG. 5 is a configuration diagram showing a processing configuration of slotting on the transmission side according to an embodiment.

FIG. 6 is a flowchart showing a transmission process according to an embodiment.

FIG. 7 is a configuration diagram showing a data processing configuration on a receiving side according to an embodiment.

FIG. 8 is a flowchart showing a receiving process according to an embodiment.

FIG. 9 is a configuration diagram showing a system configuration of a cordless telephone device.

FIG. 10 is a configuration diagram showing a communication system of a cordless telephone device.

[Explanation of symbols]

 12, 22 Radio section 13, 23 Modulation / demodulation section 14, 24 Communication control section 15, 25 ADPCM codec section 42 Voice data processing circuit 43 Error detection parity coding circuit 44 Low speed associated channel generation circuit 45 Channel type data generation circuit 46 Fixed pattern Generation circuit 47 Scramble circuit 52 Descramble circuit 53 Error detection circuit 54 Voice data processing circuit 56 Channel type determination circuit 57 Fixed pattern error number determination circuit 58 Low speed associated channel determination circuit

Claims (3)

[Claims] 1. A transmission device for transmitting burst data having a slot structure in which at least voice data, control data attached to the voice data, and an error detection code for the voice data are inserted in one slot. When there is no data to be transmitted as data, the data of the code indicating that there is no control data in the predetermined data in one slot is transmitted, and the data of the predetermined pattern is transmitted as the control data. apparatus. 2. A receiving device for receiving at least voice data in one slot, control data attached to the voice data, and burst data having a slot structure in which an error detection code for the voice data is inserted. When the absence of the control data is detected in the predetermined data in the slot, and when an error in the voice data is detected by the error detection code, a predetermined predetermined pattern arranged in the control data transmission section is used. A receiver adapted to detect an error state of data. 3. In the detected error state, when an error in the data of the predetermined pattern equal to or higher than a predetermined error rate is detected, a process of muting the audio data is performed, and the audio data having the error rate lower than the predetermined error rate is processed. The receiving apparatus according to claim 2, wherein when the error of the data of the predetermined pattern is detected, the output processing of the audio data is performed.