JP4713371B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system, and more particularly to a mobile communication system including a terminal device, a radio base station device, and a base station controller connected to the radio base station through an asynchronous transmission line such as a LAN.

  As a conventional technique related to a method for improving voice quality in a mobile communication system, for example, a technique described in Patent Document 1 is known. This prior art detects a specific difference from a signal received via a transmission path, detects a sample consisting of an ADPCM code string for performing adaptive processing, and determines a code at the time of encoder output on the transmission side from the sample. The estimated code sequence of the speech signal is compared with the received code sequence, and if the received encoded sequence is different from the estimated code sequence, the received code sequence is replaced with the estimated code sequence. is there.

  This prior art is an effective means for a communication system using a speech coding system that employs an original sound wave transmission system. However, the above-described conventional technique is unsuitable for a communication system using an encoding method close to so-called speech synthesis that generates a speech waveform by codebook search like the CELP speech encoding method.

  Also, in ARIB STD-53, which defines the standard of CDMA2000 1x that makes a call on a route of a transmitting terminal device, a radio base station, and a receiving terminal device that adopts the EVRC method as a speed conversion method for voice signal processing, When a voice frame error occurs between the transmitting side terminal device and the radio base station, the voice frame in error is replaced with a 1/8 Rate fixed pattern (OXaa44) Frame in the radio base station and received from the radio base station. An audio frame is transmitted to the terminal device on the side. By transmitting such a voice frame to the receiving terminal device, the voice decoding unit in the receiving terminal device determines that the frame is silent and performs mute processing (silence). As a result, the continuity of the audio signal is impaired, causing a problem that the listener feels uncomfortable.

  The 1/8 Rate frame described above indicates the frame rate with the Full Rate frame as the reference rate, and 1/8 indicates that the frame is 1/8 the reference rate. The same applies to the following description.

As a method for solving such a problem, the receiving terminal device has a memory for storing the audio data for 3 frames, and the audio data for 3 frames is always stored, resulting in an audio frame error. A method of interpolating a portion of an audio frame in which a frame error has occurred from the previous and subsequent frames is conceivable. However, this method causes a delay of 3 frames in the audio signal, causes an increase in cost due to an increase in the memory of the terminal device on the receiving side, and further requires an interpolation process for performing frame interpolation. As a result, the processing becomes complicated, and a new problem of uncomfortable feeling due to the delay of the audio signal is caused.
JP-A-8-223126

  In the above-described prior art, when an error occurs in a voice frame between the transmitting terminal device and the radio base station, the error frame is replaced with a 1/8 Rate fixed pattern (OXaa44) Frame in the radio base station. Since the voice frame is transmitted from the station to the receiving terminal device, the voice decoding unit in the receiving mobile terminal device determines that the frame is silent and performs a mute process. Have the problem of making you feel.

Further, the prior art described above, when transmitting the audio signal from the transmitter side of the terminal by substitution at the base station to the base station controller, between a base station and a base station controller for asynchronous When the loss of voice IP data that causes a voice frame error due to the generated CLK slip occurs, the voice signal received by the terminal device on the receiving side becomes silent (muted), and the continuity of the voice signal is impaired. It has the problem of making it feel uncomfortable.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and when a voice frame error occurs between a transmitting terminal device and a radio base station, or a voice signal from a transmitting terminal device is When a voice frame error occurs due to asynchronous communication between the base station and the base station controller when the station replaces the voice IP data and transmits it to the base station controller, By transmitting a fixed pattern frame that enables restoration (interpolation) to information from the base station controller or radio base station, restoration (interpolation) processing to audio information is performed at the receiving terminal device, and silence (mute) It is an object of the present invention to provide a mobile communication system that can improve voice quality without causing occurrence of).

According to the present invention, the object is to control a plurality of terminal apparatuses, a plurality of radio base station apparatuses that control transmission / reception of voice frames between the terminal apparatuses, and a plurality of base station apparatuses connected to the radio base station apparatuses. As a voice packet processing method between the base station controller and the base station controller, and between the base station controller and the base station controller. In a mobile communication system that performs communication using voice IP data using the EVRC method that does not support the l / 4 Rate frame, the radio base station on the transmission side generates a frame error in the voice frame received from the terminal device. If the error occurs, the voice frame in which the error has occurred is replaced with a 1/4 Rate frame and transmitted to the transmitting base station controller, and the transmitting base station controller If a frame error has occurred in the voice frame received from the radio base station apparatus, the voice frame in which the error has occurred is replaced with a 1/4 rate frame and transmitted to the network connected via the public network, The base station controller on the receiving side that has received the voice frame via the network replaces the voice frame in which the error has occurred with a 1/4 Rate frame if an error has occurred in the received voice frame. When a frame error has occurred in the received voice frame, the receiver radio base station replaces the voice frame in which the error has occurred with a 1/4 Rate frame. When the receiving terminal device detects a 1/4 Rate frame in the received voice frame, the received voice frame is transmitted to the BAD terminal device. Determining that frame, the BAD frames, is accomplished by performing an interpolation process of replacing the voice frame generated based on audio information of the previous audio frame.

  According to the present invention, a terminal device, a radio base station device, and a base station control device are configured, and the radio base station device and the base station control device are connected by a physical layer such as an asynchronous LAN (Local Area Network). In a mobile radio communication system, when an error occurs in a voice frame between the transmitting terminal device and the radio base station, or because the base station and the base station controller are asynchronous, it is caused by CLK slip. Therefore, even when IP data missing that causes a voice frame error occurs, it is possible to avoid the uncomfortable feeling that has occurred due to the loss of the continuity of the voice signal in the receiving terminal device.

  Embodiments of a mobile communication system according to the present invention will be described below in detail with reference to the drawings. In the embodiments of the present invention described below, for example, the present invention is configured by a terminal device, a radio base station device, and a base station control device, and the radio base station device and the base station control device are asynchronous in the physical layer. This is an example applied to a CDMA2000 1x mobile radio communication system connected by a local area network (LAN) or the like.

  FIG. 1 is a block diagram showing a configuration of a mobile communication system according to an embodiment of the present invention. In FIG. 1, 11 is a transmitting terminal device, 12 is a receiving terminal device, 21 is a transmitting wireless base station (hereinafter referred to as a transmitting BTS), 22 is a receiving wireless base station (hereinafter referred to as a receiving BTS). 31 is a transmitting base station controller (hereinafter referred to as a transmitting RNC), 32 is a receiving base station controller (hereinafter referred to as a receiving RNC), 5 is a network, and 211 and 221 are transmitting and receiving radio units. , 212 and 222 are Channel (MODEM), 213 and 223 are CRC encoding / decoding units, 214, 224, 412 and 422 are data replacement units, 215, 225, 311 and 321 are LAN interface units, and 41 and 42 are SDUs. Reference numerals 411 and 421 denote LOSS detection units.

A mobile communication system is generally composed of a plurality of BTSs, a plurality of RNCs, and a network connected to a public network. However, for convenience of explanation, the system shown in FIG. the side RNC 31, the receiving side RNC 32, and a receiving side BTS 22, a transmitter-side RNC 31, and the reception-side RNC 32 is shown as being connected by a network 5 which is connected to the public network.

  The transmission side BTS 21 includes a transmission / reception radio unit 211, a channel (MODEM) 212, a CRC encoding / decoding unit 213, a data replacement unit 214, and a LAN interface unit 215. Similarly, the transmission side BTS 22 Is configured to include a transmission / reception radio unit 221, a Channel (MODEM) 222, a CRC encoding / decoding unit 223, a data replacement unit 224, and a LAN interface unit 225. The transmitting RNC 31 includes a LOSS detection unit 411, a data replacement unit 412, an SDU 41, and a LAN interface unit 311. Similarly, the receiving RNC 32 includes a LOSS detection unit 421, a data replacement unit 422, an SDU 42, A LAN interface unit 321 is provided.

  In the mobile communication system configured as described above, the wireless voice signal transmitted from the transmitting terminal device 11 is received by the transmitting / receiving wireless unit 211 of the transmitting BTS 21 and each call mounted on the BTS 21 is received. The received voice frame is converted into IP (Internet Protocol) data (hereinafter referred to as voice IP data) of UDP (User Datagram Protocol) by Channel (MODEM) 212 which is a baseband modulation unit for CDMA communication allocated to The CRC code / decoding unit 213 checks whether there is a data error (error). If there is an error (error), the data replacement unit 214 replaces the erroneous data with the fixed pattern data, and then the LAN interface. It is transmitted as voice IP data to the transmitting RNC 31 via the unit 215.

  The LAN interface unit 311 of the transmission side RNC 31 receives the received voice IP data from the transmission side terminal device 11 through the traffic channel assigned to the transmission side SDU 41 which is the traffic channel transmission / reception board of the RNC 31 and receives the voice frame. The LOSS detection unit 411 detects the presence or absence of missing voice IP data. If there is data loss in this detection, the data replacement unit 412 performs replacement with the fixed pattern data, and then transmits it from the LAN interface unit 311 to the receiving RNC 32 via the network 5 connected to the public network.

  The receiving RNC 32 uses the LOSS detection unit 421 to check whether or not there is missing voice IP data that is a voice frame error in the voice IP data from the sending terminal device 11 received by the SDU 42 via the LAN interface unit 321 of the receiving RNC 32. If it is detected and data is missing, the data replacement unit 422 performs replacement with the fixed pattern data, and then transmits the voice IP data from the transmission side terminal device 11 to the reception side BTS 22 via the LAN interface unit 321.

  The receiving side BTS 22 checks the presence / absence of a data error (error) in the voice IP data received via the LAN interface unit 225 of the receiving side BTS 22, and if there is an error (error), The data replacement unit 224 replaces the data with fixed pattern data, and the baseband modulation unit Channel (MODEM) 222 demodulates the voice frame, and the transmission / reception radio unit 221 transmits the radio frame as a radio voice signal to the receiving terminal device 12.

  FIG. 2 is a diagram showing a radio section and an IP network section where a frame error occurs in the system shown in FIG.

  When a frame error (Frame Error) occurs in the upstream radio section 6 between the transmitting terminal device 11 and the transmitting BTS 21, the system according to the conventional technique is equipped with a data error mounted on the transmitting BTS 21 ( The CRC code / decoding unit 213 detects whether there is an error). If there is an error (error), the data replacement unit 214 replaces the erroneous voice frame with a fixed pattern of 1/8 Rate frame. It was sent to the receiving terminal device 12. The receiving terminal device 12 that has received the 1/8 Rate frame does not determine that the 1/8 Rate frame is a BAD frame (ErasureFrame) of ARIBSTD-53 due to the characteristics of the chipset mounted on the terminal device. In order to perform silence processing without performing restoration (interpolation) processing to an audio signal, the audio signal was in a silence (mute) state for 20 ms for one frame. For this reason, the continuity of the audio signal is impaired, and the user feels uncomfortable.

  In the ARIBSTD-53 EVRC processing that defines the standard of CDMA2000 1x, the received audio frame is determined to be a BAD frame (ErasureFrame) because of a 1/4 Rate frame, a Blank frame (Full Rate Signaling Frame), 1 / This is the case of 8 Rate frame (0xffff). This means that when an error occurs in a voice frame, a 1/4 Rate frame, a Blank frame (Full Rate Signaling Frame), and a 1/8 Rate frame (0xffff) are transmitted from the transmitting radio base station to the receiving terminal device. By doing this, it means that it is possible to prevent the sound signal from being silenced (muted) by performing a restoration (interpolation) process of the sound signal in the receiving terminal device. As a result of confirming the improvement of the phenomenon that the audio signal becomes silent (mute) for the above-mentioned 1/4 Rate frame and 1/8 Rate frame (0xffff), a remarkable improvement was obtained with the 1/4 Rate frame. .

  However, when a 1/8 Rate frame (0xffff) is used, the 1/8 Rate frame (0xffff) is not determined to be a BAD frame (ErasureFrame) due to the characteristics of the chip set that performs EVRC processing on the terminal device. In the case of a method of replacing with a 1/8 Rate frame (0xffff), there is a chip set that does not determine a 1/8 Rate frame (0xffff) as a BAD frame (ErasureFrame) in a terminal device provided by a commercial service. Considering the presence of mobile devices installed, it is not possible to avoid silence (mute) generated by transmitting a 1/8 Rate frame (Oxaa44) according to the prior art.

  In addition, when dealing with the method of transmitting a 1/4 Rate frame in order to avoid the silence (mute) phenomenon occurring in the terminal device on the receiving side, CRC error correction is not performed, so a Rate misjudgment occurs. However, the probability that the rate determination algorithm of the chipset installed in the terminal device erroneously determines a 1/4 Rate frame as a 1/8 Rate frame of a normal frame (Good Frame) According to this, the maximum is about 0.2%. In addition, the rate of occurrence of silence (mute) in the receiving terminal device is about 1/100 frames, so the probability of misjudgment is about 0.002%, and the Forward Target-FER is 1% or less. Even if this is taken into consideration, it does not affect the voice quality. Because of this extremely low probability, sending a Blank (Fu11Rate Signaling Frame), which is determined as a BAD frame (ErasureFrame), to the receiving side terminal has a higher transmission power than sending a 1/4 Rate frame to the terminal device. In the embodiment of the present invention, an error frame is replaced with a 1/4 rate frame in order to avoid a phenomenon in which a voice signal generated in a receiving terminal device becomes silent (mute). To do.

  As a result of the above-described consideration, the embodiment of the present invention is configured so that when a frame error occurs in the uplink radio section 6 between the transmission side terminal device 11 and the transmission side BTS 21, the transmission side After the voice data frame is received by the transmission / reception radio unit 211 mounted on the BTS 21, a data error (error) is detected by the CRC encoding / decoding unit 213, and the channel (MODEM) 212 mounted on the transmission side BTS 21. When converting the voice frame received by the voice IP data into the voice IP data, the data substitution unit 214 converts the data frame having a data error (frame error) detected by the CRC encoding / decoding unit 213 into a fixed pattern of 1/4 Rate frame. And is transmitted to the receiving terminal device 12 via the LAN interface unit 215.

  When the receiving terminal device 12 receives this 1/4 Rate frame, the receiving terminal device 12 sends the received 1/4 Rate frame to the ARIB STD-53 regardless of the chipset that performs EVRC processing installed in the terminal device. Based on the audio information of the previous frame, the BAD frame (ErasureFrame) is determined to be a defined BAD frame (ErasureFrame), and the BAD frame (ErasureFrame) is restored (interpolated) into a non-silent audio frame. In this audio frame restoration (interpolation) process, the previous audio frame may be used as it is, or the level of the previous audio frame may be reduced to about half, for example. For this reason, during this BAD frame (ErasureFrame), a silence (mute) state of 20 ms is established, and it is possible to avoid the uncomfortable feeling that has occurred due to the loss of the continuity of the audio signal.

  As shown in FIG. 2, a frame error may occur not only in the above-described wireless section but also in the IP network section.

  In FIG. 2, the transmitting side BTS 21 and the transmitting side RNC 31 are connected by an asynchronous LAN in the physical layer of the LAN interface unit 215 of the BTS 21 and the LAN interface unit 311 of the RNC 31 to transmit and receive voice IP data. Yes.

  Conventionally, due to a CLK slip that occurs because the voice IP data transmitted from the transmitting side BTS 21 to the transmitting side RNC 31 is asynchronous, a lack of the voice IP data resulting in a voice frame error has occurred with the upstream transmitting side BTS 21. If the LOSS detection unit 411 detects that the voice IP data that occurs in the section 7 with the transmitting side RNC 31 and is received by the SDU 41 is missing as the next voice IP data after the Full Rate voice IP data, data replacement is performed. The unit 412 replaces the missing voice IP data with a 1/8 Rate frame and transmits it to the receiving terminal device 12.

  The receiving side terminal device 12 that has received this 1/8 Rate frame does not determine the 1/8 Rate frame as an ARIB STD-53 BAD frame (ErasureFrame) due to the characteristics of the chipset mounted on the terminal device. In addition, silence processing was performed without performing restoration (interpolation) processing on the audio signal, and the audio signal was silenced (muted) for 20 ms for one frame, causing the continuity of the audio signal to be lost and causing a sense of incongruity. .

  In the embodiment of the present invention, the lack of voice IP data resulting in a voice frame error occurs in the section 7 between the upstream transmission side BTS 21 and the transmission side RNC 31, and the voice IP data received by the SDU 41 is full rate. When the LOSS detection unit 411 detects that the next voice IP data after the voice IP data is missing, the data replacement unit 412 replaces the missing voice IP data with a ¼ Rate frame and sends it to the receiving terminal device 12. .

  The receiving terminal device 12 that has received this 1/4 Rate frame uses the BAD defined in ARIB STD-53 regardless of the chip set that performs EVRC processing on the 1/4 Rate frame. A frame (ErasureFrame) is judged, and the BAD frame (ErasureFrame) is restored (interpolated) to a non-silent audio frame based on the audio information of the previous frame. Thus, it is possible to avoid the uncomfortable feeling that has occurred due to the loss of the continuity of the audio signal.

  In FIG. 2, the transmitting RNC 31 and the receiving RNC 32 are connected by an asynchronous LAN in the physical layer of the LAN interface unit 311 of the transmitting RNC 31 and the LAN interface unit 321 of the receiving RNC 32. Voice IP data is transmitted / received via a network 5 constituted by a router device or the like which is a network relay device for transmitting / receiving data.

  Conventionally, due to the CLK slip generated because the voice IP data transmitted from the transmitting RNC 31 to the receiving RNC 32 is asynchronous, the lack of the voice IP data resulting in a voice frame error is received by the upstream transmitting RNC 31. When the LOSS detection unit 421 detects that the voice IP data generated in the section 8 with the side RNC 32 and received by the SDU 42 is missing as the next voice IP data after the Full Rate voice IP data, the data replacement unit 422 Replaces the missing voice IP data with a 1/8 Rate frame and transmits it to the receiving terminal device 12.

  The receiving side terminal device 12 that has received this 1/8 Rate frame does not determine the 1/8 Rate frame as an ARIB STD-53 BAD frame (ErasureFrame) due to the characteristics of the chipset mounted on the terminal device. In addition, silence processing was performed without performing restoration (interpolation) processing on the audio signal, and the audio signal was silenced (muted) for 20 ms for one frame, causing the continuity of the audio signal to be lost and causing a sense of incongruity. .

  In the embodiment of the present invention, voice IP data loss resulting in a voice frame error occurs in the section 8 between the transmitting RNC 31 and the receiving RNC 32, and the voice IP data received by the SDU 42 is after the Full Rate voice IP data. When the LOSS detection unit 421 detects that the next voice IP data is missing, the data replacement unit 422 replaces the missing voice IP data with a ¼ Rate frame and sends it to the receiving terminal device 12.

  The receiving terminal device 12 that has received this 1/4 Rate frame uses the BAD defined in ARIB STD-53 regardless of the chip set that performs EVRC processing on the 1/4 Rate frame. A frame (ErasureFrame) is judged, and the BAD frame (ErasureFrame) is restored (interpolated) to a non-silent audio frame based on the audio information of the previous frame. Thus, it is possible to avoid the uncomfortable feeling that has occurred due to the loss of the continuity of the audio signal.

  In FIG. 2, the downlink receiving side RNC 31 and the receiving side BTS 22 are connected by an asynchronous LAN in the physical layer of the LAN interface unit 321 of the receiving side RNC 31 and the LAN interface unit 225 of the receiving side BTS 22, and the voice IP data Sending and receiving.

  Conventionally, due to the CLK slip generated because the voice IP data transmitted from the receiving side RNC 31 to the receiving side BTS 21 is asynchronous, the lack of the voice IP data resulting in a voice frame error results in the receiving side RNC 32 and the receiving side BTS 22 on the downstream side. When the voice IP data that occurs at 9 and received by the CRC encoding / decoding unit 223 is detected as a lack of the next voice IP data after the Full Rate voice IP data, the data replacement unit 224 The transmitted voice IP data is replaced with a 1/8 Rate frame and transmitted to the receiving terminal device 12.

  The receiving side terminal device 12 that has received the 1/8 Rate frame does not determine the 1/8 Rate frame as an ARIB STD-53 BAD frame (ErasureFrame) due to the characteristics of the chipset mounted on the terminal device. In addition, silence processing was performed without performing restoration (interpolation) processing on the audio signal, and the audio signal was silenced (muted) for 20 ms for one frame, causing the continuity of the audio signal to be lost and causing a sense of incongruity. .

  In the embodiment of the present invention, voice IP data loss resulting in a voice frame error occurs between the receiving side RNC 32 and the receiving side BTS 22 on the downstream side, and the voice IP data received by the CRC encoding / decoding unit 223 is Full. When it is detected that the next voice IP data after Rate voice IP data is missing, the data replacement unit 224 replaces the missing voice IP data with a ¼ Rate frame and sends it to the receiving terminal device 12.

  The receiving terminal device 12 that has received this 1/4 Rate frame uses the BAD defined in ARIB STD-53 regardless of the chip set that performs EVRC processing on the 1/4 Rate frame. A frame (ErasureFrame) is judged, and the BAD frame (ErasureFrame) is restored (interpolated) to a non-silent audio frame based on the audio information of the previous frame. Thus, it is possible to avoid the uncomfortable feeling that has occurred due to the loss of the continuity of the audio signal.

  An error may also occur in the voice frame transmitted from the receiver BTS 22 to the receiver terminal device 12, but in the embodiment of the present invention, the error here is not dealt with.

  FIG. 3 is a sequence chart for explaining the operation of detecting the loss of voice IP data described with reference to FIG. 2. Next, this will be described.

  As shown in FIG. 1 and FIG. 2, between the transmitting side BTS 21 and the transmitting side RNC 31, between the transmitting side RNC 31 and the receiving side RNC 32, and between the receiving side RNC 32 and the receiving side BTS 22, respectively. The voice IP data is transmitted and received through a network connected to the LAN interface unit. The voice IP data is transmitted by the BTS 21 or RNC 31 that transmits the voice IP data, transmitting the voice IP data to the RNC 32 and the BTS 22 on the receiving side via the network connected to each LAN interface unit. The LOSS detection unit 421 mounted on the RNC 32 or the CRC encoding / decoding unit 223 mounted on the BTS 22 confirms the Timestamp in the header information of the voice IP data and detects the lack of the voice IP data. It is done like that. This operation sequence will be described in more detail with reference to FIG.

(1) The BTS 21 or RNC 31 that transmits the voice IP data adds Timestamp A to the voice IP data by the channel 212 or the SDU 41 installed in the RNC 31 installed in the BTS 21, and sends this voice IP data to the receiving RNC 32, Transmit to the BTS 22 (sequence 301).

(2) When the receiving side RNC 32 and BTS 22 receive the voice IP data, the LOSS detection unit 421 mounted on the RNC 32 and the Timestamp A54 of the voice IP data received by the CRC encoding / decoding unit 223 mounted on the BTS 22 Confirm. Timestamp is detected by the LOSS detection unit 421 mounted on the RNC and the CRC code / decoding unit 223 mounted on the BTS 22 every 20 ms because a voice frame is added every frame. (Sequence 302).

(3) When the communication between the BTS and the RNC is asynchronous, and there is no voice IP data loss resulting in a voice frame error due to the CLK slip, it is installed in the Channel 212 or RNC 31 installed in the transmitting BTS 21. When the voice IP data to which Timestamp is added in the order of Timestamp A54, Timestamp B55, Timestamp C56, and Timestamp D57 is transmitted every time the voice IP data is transmitted, the receiving RNC 32 and BTS 22 Similarly, voice IP data is received in the order of Timestamp A54, Timestamp B55, Timestamp C56, and Timestamp D57 from the received voice IP data, and it is determined that there is no missing voice IP data (sequences 303 to 305).

(4) In the middle of the above-described sequence, the voice IP data transmitted to the receiving side RNC 32 and BTS 22 becomes a voice frame error due to a CLK slip because the BTS and RNC are asynchronous, and the voice IP data It is assumed that data loss 58 occurs at Timestamp C. In this case, the receiving RNC 32 and the BTS 22 have lost the voice IP data to which the Timestamp C56 is added in the LOSS detection unit 421 mounted in the RNC 32 and the CRC encoding / decoding unit 223 mounted in the BTS 22. Can not be confirmed. For this reason, the order of reception of the voice IP data is Timestamp A54, Timestamp B55, and Timestamp D57. Therefore, the RNC 32 and BTS 22 on the receiving side of the voice IP data use the data replacement units 422 and 224 mounted on the RNC and BT as shown in FIG. The frame is replaced with a 1/4 Rate frame and transmitted to the terminal device 12 on the receiving side.

  FIG. 4 is a flowchart for explaining the processing operation of the voice IP data loss determination described with reference to FIG. 3, and this will be described next.

(1) The receiving RNC and BTS that have received the voice IP data check the Timestamp of the voice IP data received by the LOSS detection unit installed in the RNC and the CRC encoding / decoding unit installed in the BTS ( Steps 61 and 62).

(2) The LOSS detection unit mounted on the RNC and the CRC encoding / decoding unit mounted on the BTS use the current received frame (determination target voice IP data) to determine the voice frame error of the received voice IP data. ) Is equal to the time stamp obtained by adding 20 ms (M), which is one frame length of the audio frame, to the time stamp N of the frame received immediately before (step 63).

(3) If Y = N + M is established in the determination of step 63, it can be determined that the voice IP data has been normally received. Therefore, the voice IP data received by the own BTS or the own RNC is downstream. BTS and RNC are transmitted (step 64).

(4) On the other hand, if Y = N + M is not established in the determination of step 63, it can be determined that the voice IP data has not been received normally. Therefore, as described with reference to FIG. Then, the data replacement unit installed in the RNC replaces the missing voice IP data with the 1/4 Rate frame, and sends it to the receiving side BTS, RNC or the receiving side terminal device 12 on the downstream side (step 65). ).

(5) After the processes in steps 64 and 65, the next voice IP data reception process is performed in the same manner as described above (step 66).

  FIG. 5 is a flowchart for explaining an error detection processing operation of the voice IP data described with reference to FIGS. 2 and 3, which will be described next.

(1) A frame error occurs in a voice frame in the radio section from the mobile terminal device on the transmission side to the base station when voice communication is performed in which wireless connection is established between terminal devices via the base station. In this case, when the transmitting side BTS 21 receives the voice frame from the transmitting side terminal transmission 11, the transmitting side BTS 21 determines whether or not there is a data error (error) by the CRC code / decoding unit 213 of the BTS 21 (step 131).

(2) If no frame error is detected in the voice frame from the transmission side terminal device 11 in the determination in step 131, the transmission side BTS 21 sends the reception voice frame to the transmission side RNC 31 as voice IP data. When a frame error is detected, the data replacement unit 214 replaces the error frame with a 1/4 Rate frame and transmits it to the 1/4 Rate frame RNC 31 (steps 132 and 133).

(3) The transmitting RNC 31 that has received the voice IP data from the BTS 21 uses the LOSS detection unit 411 to detect whether or not the voice IP data is missing in the received voice IP data, and the voice IP data is missing. If there is no voice IP data, the voice IP data is transmitted to the receiving RNC 32 via the network 5 constituted by a router device or the like that is a network relay device for transmitting and receiving voice IP data (steps 134 and 135).

(4) If the LOSS detection unit 411 of the RNC 31 detects the lack of voice IP data in the judgment in step 134, it is judged whether or not the missing voice IP data is data received next to the Full Rate voice IP data. If the missing voice IP data is not the next of the full rate voice IP data, or an error other than missing data, the received voice IP data is received via the network 5 as it is. To the side RNC 32 (steps 136 and 135).

(5) If it is determined in step 136 that the missing voice IP data is data received next to the Full Rate voice IP data, the data replacement unit 412 converts the missing voice IP data into a 1/4 Rate frame. Then, the ¼ Rate frame is transmitted to the receiving RNC 32 via the network 5 constituted by a router device or the like that is a network relay device that transmits and receives voice IP data (step 137).

(6) The receiving RNC 32 that has received the voice IP data from the RNC 31 uses the LOSS detection unit 421 to detect whether or not the voice IP data is missing in the received voice IP data, and there is no voice IP data missing. In this case, the received voice IP data is transmitted to the receiver BTS 22 (steps 138 and 139).

(7) If the LOSS detection unit 421 of the RNC 32 detects the lack of voice IP data in the process of step 138, whether or not the missing voice IP data is data received next to the Full Rate voice IP data. When the determination is made and the missing voice IP data is not the next of the full rate voice IP data or an error other than missing data, the received voice IP data is transmitted to the receiver BTS 22 as it is. (Steps 1310 and 139).

(8) If it is determined in step 1310 that the missing voice IP data is data received next to the Full Rate voice IP data, the data replacement unit 422 converts the missing voice IP data into a 1/4 Rate frame. Then, the 1/4 Rate frame is transmitted to the receiving BTS 22 (step 1311).

(9) The receiving BTS 22 that has received the voice IP data from the RNC 32 uses the CRC encoding / decoding unit 223 to detect whether or not the voice IP data is missing in the received voice IP data. If there is no omission, the received data is transmitted as it is from the transmission / reception radio section 221 to the receiving terminal device 12 as a radio audio signal (steps 1312 and 1313).

(10) When the CRC encoding / decoding unit 223 of the BTS 22 detects the lack of the voice IP data in the determination of step 1312, the missing voice IP data is the data received next to the Full Rate voice IP data. If the missing voice IP data is not the next of the full rate voice IP data, or if it is an error other than missing data, the received voice IP data is received as it is. It transmits to the side terminal device 12 (steps 1314 and 1313).

(11) If it is determined in step 1314 that the missing voice IP data is data received next to the Full Rate voice IP data, the data replacement unit 422 converts the missing voice IP data into a 1/4 Rate frame. Then, the 1/4 Rate frame is transmitted to the receiving terminal device 12 (step 1315).

(12) The receiving side terminal device 12 determines whether or not the received voice frame data is ¼ rate frame data. If the voicing side terminal device 12 has received a voice frame other than the ¼ rate frame, interpolation processing is performed. The audio signal is output without performing the steps (steps 1316 and 1317).

(13) If it is determined in step 1316 that the received voice frame data is ¼ rate frame data, the receiving terminal device 12 sends the received ¼ rate frame data to the terminal device. Regardless of the chipset that performs EVRC processing, the BAD frame (ErasureFrame) defined in ARIBSTD-53 is determined, and the BAD frame (ErasureFrame) is converted into the audio frame based on the audio information of the previous frame. A restoration (interpolation) process is performed to output an audio signal (step 1318).

  Since the receiving side terminal device 12 performs processing for restoring (interpolating) a BAD frame (ErasureFrame) into a voice frame based on the voice information of the previous frame, and outputs the received 1/4 Rate frame data. It becomes silent (mute) for 20 ms, and it is possible to avoid a sense of incongruity caused by the loss of continuity of the audio signal.

  FIG. 6 is a diagram illustrating an example of a speech waveform output when the receiving terminal device 12 receives a 1/8 Rate frame.

  When the receiving side terminal device 12 receives the 1/8 Rate frame, the receiving side terminal device 12 does not perform voice information interpolation (restoration) processing, so 20 ms of silence for one frame of the BAD frame (ErasureFrame) (mute) ) Period 14 occurs, and the audible quality on the receiver side deteriorates.

  FIG. 7 is a diagram illustrating an example of a speech waveform output when the receiving terminal device 12 receives a 1/4 Rate frame.

  When the receiving terminal device 12 receives the 1/4 Rate frame, the receiving terminal device 12 restores (interpolates) the sound information based on the sound information of the frame before receiving the frame error (Frame Error). Therefore, the 20 ms silence (mute) period 15 that occurred when the 1/8 Rate frame was received does not occur, so that the continuity of the audio signal is impaired and the uncomfortable feeling that has occurred is avoided. And the audible quality on the receiver side can be improved.

  According to the above-described embodiment of the present invention, the terminal apparatus, the radio base station apparatus, and the base station control apparatus are configured, and the radio base station apparatus and the base station control apparatus are physically connected by an asynchronous LAN (Local Area Network) or the like. In mobile radio communication systems connected by layer, when an error occurs in a voice frame between the transmitting terminal device and the radio base station, or because the base station and the base station controller are asynchronous. When IP data loss occurs that causes a voice frame error due to a CLK slip, the base station or the base station controller transmits a 1/4 Rate frame to the receiver terminal so that the receiver terminal receives the previous frame of voice. Since audio frame error restoration (interpolation) processing is performed based on information, silence (mute) is entered, and the continuity of the audio signal is impaired, thereby avoiding the uncomfortable feeling that occurred. The ability.

It is a block diagram which shows the structure of the mobile communication system by one Embodiment of this invention. It is the figure which showed the radio | wireless area and IP network area where a frame error (Frame Error) generate | occur | produces in the system shown in FIG. FIG. 3 is a sequence chart illustrating an operation for detecting missing voice IP data described with reference to FIG. 2. FIG. FIG. 4 is a flowchart for explaining a processing operation of voice IP data loss determination described with reference to FIG. 3. FIG. FIG. 4 is a flowchart for explaining an error detection processing operation for voice IP data described with reference to FIGS. 2 and 3; FIG. It is a figure which shows the example of the audio | voice waveform output when the receiving side terminal device receives a 1/8 Rate frame. It is a figure which shows the example of the audio | voice waveform output when a receiving side terminal device receives a 1/4 Rate frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transmission side terminal device 12 Reception side terminal device 21 Transmission side radio base station (transmission side BTS)
22 Receiver radio base station (receiver BTS)
31 Sender base station controller (sender RNC)
32 Receiver base station controller (receiver RNC)
5 Network 211, 221 Transmission / reception radio section 212, 222 Channel (MODEM)
213, 223 CRC encoding / decoding section 214, 224, 412, 422 Data replacement section 215, 225, 311 and 321 LAN interface section 41, 42 SDU
411, 421 LOSS detector

Claims (3)

A plurality of terminal apparatuses, a plurality of radio base station apparatuses that control transmission / reception of voice frames between the terminal apparatuses, a plurality of base station control apparatuses connected to the radio base station apparatus, and a base station control apparatus And supports a 1/4 rate frame as a voice packet processing method between the radio base station and the base station controller and between the base station controllers. In a mobile communication system that performs communication using voice IP data using a non-EVRC method,
When a frame error has occurred in the voice frame received from the terminal device, the transmitting base station replaces the voice frame in which the error has occurred with a 1/4 Rate frame and controls the transmitting base station. To the device,
When a frame error has occurred in the voice frame received from the transmitter radio base station apparatus, the base station controller on the transmitting side replaces the voice frame on which the error has occurred with a 1/4 rate frame. To the network connected through the public network,
The base station controller on the receiving side that has received the voice frame via the network replaces the voice frame in which the error has occurred with a 1/4 Rate frame if an error has occurred in the received voice frame. Send to the receiving base station,
When a frame error has occurred in the received voice frame, the receiving radio base station replaces the voice frame in which the error has occurred with a 1/4 Rate frame and transmits the frame to the receiving terminal device,
When the terminal device on the receiving side detects a 1/4 Rate frame in the received voice frame, it determines that the received voice frame is a BAD frame, and uses the BAD frame based on the voice information of the previous voice frame. A mobile communication system characterized by performing an interpolation process for replacing the generated voice frame . 2. The mobile communication system according to claim 1 , wherein the interpolation processing is interpolation processing using speech information of the previous speech frame as it is or interpolation processing using speech information whose level of the previous speech frame is changed . The radio base station apparatus and the base station control apparatus determine whether a voice frame in which a frame error has occurred is received next to a full-rate voice frame;
If not received after the Full Rate audio frame, send the received audio frame as is,
3. The mobile communication system according to claim 1 , wherein when it is received next to a full rate audio frame, a replacement process with the 1/4 rate frame is performed .