KR100541773B1 - Method for transcoding two or more codecs in communication system - Google Patents

Abstract

The present invention relates to a method of transcoding between tacodecs in a communication system, and even when the AMR codec and the tacodec are transcoded in a wideband CDMA communication system, even if the source codec transmission rate is the same, transcoding prefree is not physically allocated. By performing an operation and setting up a call, not only the sound quality is deteriorated but also the advantage of saving transcoder resources.

W-CDMA, Codec, AMR, RrFO, Codec Negotiation, GSM-EFR, FR-ARM

Description

METHODE FOR TRANSCODING TWO OR MORE CODECS IN COMMUNICATION SYSTEM}             

1 is a block diagram schematically illustrating a functional structure of an AMR codec.

2 is a block diagram showing a basic broadband CDMA communication system structure.

3 is a signal flow diagram illustrating a method for transcoding between tacodecs in a communication system according to the present invention.

4 is a flowchart illustrating a method of transcoding between tacodecs in the communication system according to the present invention shown in FIG. 4.

   -Explanation of symbols for the main parts of the drawings-

110: calling terminal 120: calling wireless network controller

130: originating exchange 132: first server

134: first media gateway 140: receiving side exchange

142: second server 144: second media gateway

150: receiving side wireless network controller 160: receiving side terminal

The present invention relates to a transcoding method between tacodecs in a communication system. More specifically, the transcoder is not physically allocated even when the source codec transmission rate is the same when transcoding between an AMR codec and a tacodec in a wideband CDMA communication system. The present invention relates to a method of transcoding between tacodecs in a communication system that not only prevents degradation of sound quality by making a call setup by performing transcoding pre-operation but also saves transcoder resources.

In a wireless communication system, a mobile station and infrastructure equipment supporting the mobile station can be negotiated with each other to reach a specific service configuration. This negotiation process is commonly referred to as a service negotiation procedure, which is necessary because the mobile station may request certain services from an infrastructure not supported by the infrastructure or vice versa. to be.

Therefore, in order to implement such a service negotiation procedure, if a mobile station requests a transcoder to be executed in a different form during communication after having a plurality of different transcoders in the infrastructure, the service negotiation procedure is executed to accommodate the request of the mobile station. When communication between the rescue facility and the mobile station is established, only one type of transcoder in the infrastructure is assigned to a particular communication to provide a predetermined service.

Adaptive Multi Rate Codec (AMR) is adopted as a narrow band mandatory speech codec in 3GPP SA WG4, which establishes detailed specifications of the wideband CDMA scheme, and its functional structure is shown in FIG. As shown.

The transmitting side has two input stages, one is an analog input stage and a mobile station (MS), and the other is a RNC (Radio Network Controller) having digital input. The input signal of No. ① is modulated by the modulator 10 to make a uniform 13 bit as an 8-bit A-law or μ-law PCM signal. The analog signal passes through a low pass filter (LPF) 20 and is then A / D converted by the A / D converter 30. The signal of ②, which is the sum of the above two signals, becomes a uniform 13-bit PCM signal and is input to a speech encoder 50. The input signal is separated into a Voice Activity Detector (VAD) 40 and a Comfort Noise Tx Functions (60), and the voice activity selector 40, which is the signal of ③, and the encoder language, ④. A frame (50) and a Silence Descriptor (SID) frame of the transmission function noise reducer 60, which are ⑤, are input to the Discon Tinuos Mixed Transmission (DTX) controller 70. The signal output from the DTX controller 70 is spread through the CRC, channel encoding, and block interleaving.

As such, the AMR codec has a structure in which an input terminal can simultaneously accommodate analog voice and digitized voice, and according to the code mode, the source codec bit rate is 4.75kbps to 12.2 kbps. There are one language mode and one DTX (Discon Tinuos Mixed Transmission) mode of 1.8kbps.

When the AMR vocoded signal is transmitted from the calling mobile terminal to the mobile switching center (MSC; Mobile Switching Center), AMR decoding is performed at the calling exchange, then the transcoder is allocated, converted, and transmitted to the receiving exchange. After the decoding, the call request is made to the receiving terminal, and the voice call path is established through vocoding and decoding by the codec supported by the receiving terminal.

However, when the codec provided by the receiving terminal is the same as the calling terminal with the AMR codec, the voice data is double-coded and decoded during receiving and receiving, and the resources of the transcoder are wasted due to the transcoder allocation. There is a problem that the sound quality is degraded due to repeated encoding and decoding.

So, in order to solve this problem, when the calling terminal and the receiving terminal use the same codec, it is similar to the vocoder bypass function of CDMA. When the terminal and the receiving terminal use the same codec, the Transcoder Free Operation (TrFO) function, which transmits without physically assigning the transcoder, provides a resource saving and a sound quality improvement of the transcoder.

As such, if the codecs provided by the calling terminal and the receiving terminal are the same, the TrFO function may be provided as described above, but if the codecs provided by the calling terminal and the receiving terminal are not the same, the TrFO function may be provided. Since the transcoder must be allocated at the exchange, the encoding / decoding operation for the voice is repeatedly performed, thereby deteriorating the sound quality.

However, even if the codecs are different, the 12.2K mode of the same AMR codec and the GSM-EFR codec or the FR-AMR codec cannot provide the TrFO function due to the different codecs, which wastes the resources of the transcoder. There is a problem in that sound quality is degraded due to encoding and decoding.

The present invention has been made to solve the above problems, and an object of the present invention is to physically allocate a transcoder even when the source codec transmission rate is the same when transcoding between an AMR codec and a tacodec in a broadband CDMA communication system. The present invention provides a method of transcoding between tacodecs in a communication system that not only prevents a deterioration in sound quality by performing a call encoding by performing a transcoding preoperation but also saves transcoder resources.

The present invention for realizing the above object is a step of receiving a codec type when a call setup request from the calling terminal to the calling exchange, and transmitting the codec type of the calling terminal received from the calling exchange to the receiving exchange. Requesting preparation of call setup from the receiving exchange to the receiving terminal, receiving a codec type when confirming the call setting at the receiving terminal, and the codec type of the receiving terminal received from the receiving exchange. A method of transcoding between tacodecs in a communication system comprising comparing a codec type of a calling terminal with a codec type and setting a TrFO call when the codec types are the same. If not, the step of comparing the transmission rate of the codec types of the calling terminal and the receiving terminal is the same, and comparing the rate. When setting a TrFO call and not be the same if the is characterized in that made in further comprising the step of establishing a call by assigning a transcoder.

The codec of the calling terminal and the receiving terminal having the same data rate is characterized by the 12.2k mode of the AMR codec and the GSM-EFR codec or the FR-AMR codec.

In the present invention made as described above, even if the type of codec provided by the calling terminal and the receiving terminal through the codec negotiation in the broadband CDMA communication network is different from each other by the AMR codec and the GSM-EFR codec or the FR-AMR codec, the source codec transmission rate may be the same. In this case, it works to provide TrFO function.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present embodiment is not intended to limit the scope of the present invention, but is presented by way of example only and the same parts as in the conventional configuration using the same reference numerals and names.

2 is a block diagram showing a basic broadband CDMA communication system structure.

As shown here, the calling party terminal 110 is connected to the calling party exchange 130 through the calling party wireless network controller 120, and the receiving terminal 160 is also connected through the receiving party wireless network controller 150. It is connected to the receiving exchange 140.

In addition, the source exchange 130 and the destination exchange 140 are connected to perform a call exchange control period through a bearer independent call control (BICC) protocol, which is a manganese call control protocol. Codec information supported by the receiving terminal 160 may be received.

In addition, the source exchange 130 is configured in a substantially separate structure of the first server (132) and the first media gateway (MGW; Media GateWay, 134), the receiving side exchange 140 is also substantially The second server 142 and the second media gateway MGW (Media GateWay 144) are physically separated from each other.

Accordingly, the first to second servers 132 and 242 output a control signal (MGW control) at the time of call setup using the MEGACO (Media Gateway Control) protocol, respectively. CSF (Call Serving Function) by controlling the role, the first to second media gateways (134, 144) in order to perform the media conversion (media conversion) between different networks (network) to bearer (Bearer) type Therefore, the bearer control protocol is used to perform both the bearer control function (BCF) and the bearer function (BF).

Meanwhile, the first to second servers 132 and 142 control the calling side wireless network controller 120 and the receiving side wireless network controller 150 by using a RANAP signal to transmit each terminal 110. ) And the receiving terminal 160 selectively controls the transmission rate of the bearer by the codec.

In addition, the originating terminal 110 and the receiving terminal 160 perform codec negotiation with the first to second servers 132 and 142, and the originating exchange 130 and the receiving side exchange ( 140 performs codec negotiation between the first and second servers 132 and 142 and transmits the first to second media gateways 134 and 144 from the first to second servers 132 and 142 according to the execution result. It will instruct coder assignment or perform TrFO function without transcoder assignment.

Specifically, a signal flow chart for explaining a tacodec transcoding method in a communication system according to the present invention shown in FIG. 3 and a tacodec transcoding method in a communication system according to the present invention shown in FIG. 4 will be described. Referring to the flow chart for the following.

First, the caller terminal 110 transmits that the codec type provided by the caller terminal 130 is AMR_12.20 mode of the AMR codec while requesting call setup from the caller terminal 110 to the caller switch 130 (S10). .

Then, the codec type of the originating terminal 110 received from the originating exchange 130 is transmitted to the receiving exchange 140 by the BICC protocol (S20).

Then, in order to set up the call received from the originating exchange 130, the receiving side exchange 140 requests the preparation of the call setting to the receiving side terminal 160 (S30).

At this time, while the call setup is confirmed between the receiving terminal 160 and the receiving exchange 150, the codec type provided by the receiving terminal 160 through the codec negotiation is transmitted as GSM-EFR (S40).

Then, through the process of transmitting the codec type received from the receiving terminal 160 from the receiving terminal 160 back to the calling exchange 130, the codec negotiation between the calling exchange 130 and the receiving exchange 140 is performed. It is performed (S50).

After performing the codec negotiation as described above, the source exchange 130 compares the codec type provided by the receiving terminal 160 received from the receiving exchange 140 with the codec type provided by the calling terminal 110. It becomes (S60).

Therefore, if the codec types are the same, the media gateway is instructed to perform the TrFO function without the transcoder assignment, and the bearer, which is coded data transmitted from the originating terminal 110, is directly transmitted to the receiving exchange 140. A call is established with the receiving terminal 160 (S60) (S70).

However, when the codec types provided by the calling terminal 110 and the receiving terminal 160 are not the same, the source codec transmission rates of the codecs provided by the calling terminal 110 and the receiving terminal 160 are compared with each other. (S80). In this case, when the calling terminal 110 has a transmission rate of 12.2 kbps, which is the AMR_12.20 mode of the AMR codec, and the receiving terminal 160 provides the GSM-EFR codec or the FR-AMR codec, the data rates are the same. .

Even in such a case, the call setup is performed to perform the TrFO function of directly transmitting the coded data from the calling terminal 110 to the receiving side exchange 140 without allocating a transcoder (S70).

However, when not only the codec types provided by the calling terminal 110 and the receiving terminal 160 are different, but also the transmission rates are also different, the call setup is performed by allocating a transcoder to repeat encoding and decoding. To be made (S90) (S100).

As described above, the present invention provides sound quality by performing transcoding preoperation without physically assigning a transcoder even when the source codec transmission rate is the same when transcoding between an AMR codec and a tacodec in a broadband CDMA communication system. In addition to preventing degradation, it also has the advantage of saving transcoder resources.

Claims (4)

Receiving a codec type when a call setup request is made from a calling terminal to a calling exchange, transmitting the codec type of the calling terminal received from the calling exchange to a receiving exchange, and receiving at the receiving exchange. Requesting preparation of a call setup to a side terminal, receiving a codec type when confirming a call setup at the receiving terminal, and a codec type of the receiving terminal received from the receiving exchange and the originating terminal. A method of transcoding between tacodecs in a communication system, comprising: comparing a codec type and setting a TrFO call when the codec types are the same. Comparing the codec types with each other if the transmission rate of the codec types of the calling terminal and the receiving terminal is not the same; Setting a call by setting a TrFO call if the transmission rate is the same and assigning a transcoder if the transmission rate is not the same. Tacodec transcoding method in a communication system characterized in that it further comprises. The method according to claim 1, wherein the codecs of the transmitting terminal and the receiving terminal having the same data rate are AMR codec and GSM-EFR codec. The method of claim 1, wherein the codecs of the source terminal and the receiver terminal having the same data rate are AMR codec and FR-AMR codec. 4. The method according to claim 2 or 3, wherein the AMR codec is in AMR_12.20 transmission mode.

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