KR19990084895A - Codec Bypass Method of Mobile Switch - Google Patents

Abstract

The present invention transfers information related to the codec bypass function when the traffic occurs during the exchange period, so that the codec operates in the bypass mode, so that duplicate transcoding is performed during a mobile to mobile call. The present invention relates to a codec bypass method of a mobile communication exchange that prevents a degradation of call quality caused by the present invention. A message transmission process of transmitting an ISUP message to a large station after inserting F-IE parameter information for determining codec bypass in a part of an ISUP message in case of communication with a mobile subscriber; The large station receiving the ISUP message checks the F-IE parameter of the ISUP message and executes a message receiving process that changes the local call processing block to the bypass mode in the codec bypass mode, thereby preventing double transcoding. It will improve quality.

Description

Codec Bypass Method of Mobile Switch

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch in a digital cellular system (DCS), and in particular, when a traffic occurs during an exchange, the codec operates in a bypass mode by transferring information related to a codec bypass function. Accordingly, the present invention relates to a codec bypass method of a mobile communication exchange that prevents the degradation of call quality caused by duplicate transcoding in a mobile to mobile call.

In general, voice data conversion of a digital cellular system is roughly divided into a voice conversion process during a call between a cellular phone (hereinafter referred to as a "mobile") and a wired subscriber, and a voice conversion process during a call between a mobile and a mobile.

1 is a view for explaining a voice transmission and reception relationship between a mobile and a wired subscriber in a general digital cellular system.

Here, reference numeral 1 is a mobile, 2 is a base station, 3 is a base station controller having a vocoder for converting voice packet data and PCM (Pulse Code Modulation) data, 4 is a switch, and 5 is a wired subscriber. One landline phone.

In a general digital cellular system having such a configuration, a voice transmission / reception method between a mobile and a wired subscriber includes voice compression, that is, encoding (ie, encoding) in a vocoder in a mobile (1) that performs voice compression and decompression by inputting PCM data digitized voice data. Encoding is performed, in which packet data is generated, which is transmitted to the base station 2 via an air section.

The voice packet data via the base station 2 is transmitted to the base station controller 3, and the vocoder in the base station controller 3 converts the transmitted voice packet data into PCM data.

The PCM data converted as described above is transferred to the wired telephone 5 provided by the wired subscriber via the switch 4.

And the voice generated from the landline subscriber 5 of the landline subscriber proceeds in reverse to the above-described operation and is transmitted to the mobile 1.

2 is an explanatory diagram for explaining a voice transmission and reception relationship between a mobile and a mobile in a general digital cellular system.

Here, reference numeral 6 denotes a first mobile, 7 denotes a first base station, 8 denotes a first base station controller, 9 denotes a switchboard, 10 denotes a second base station controller, 11 denotes a second base station, and 12 denotes a second mobile.

The voice transmission and reception between the mobile and the mobile of the digital cellular system made with such a connection are more lossy because the vocoding process is performed once more than when the mobile and the wired subscribers are talking.

Therefore, during the call between the mobile and the mobile, the first base station controller 8 does not perform vocoding (without converting the packet data), transfers the timing of encoding and decoding as it is, and adjusts only the output format in PCM format. .

The data generated at this time is called bypass data.

The vocoder in the counterpart second base station controller 10 also performs only a role of converting bypass data into packet data.

This operation of the vocoder is called bypass operation (bypass mode).

On the other hand, when the mobile communication exchange and the other mobile communication switching period are interlocked, since the information related to the service option among the characteristics of the subscriber is not known, the transmitting data is unconditionally transcoded by the calling mobile communication exchange and the called party The mobile communication exchange also sets up a call by transcoding the received data.

As described above, however, since double transcoding is performed even when traffic between the mobile communication exchange and the mobile communication switching period occurs, that is, when a subscriber has the same service option, loss of voice data occurs and call quality (sound quality) is degraded. Caused problems.

Accordingly, the present invention has been proposed to solve various problems occurring in the conventional digital cellular system as described above.

The present invention transfers information related to the codec bypass function when the traffic occurs during the exchange period, so that the codec operates in the bypass mode, so that duplicate transcoding is performed during a mobile to mobile call. It is an object of the present invention to provide a codec bypass method of a mobile communication exchange that prevents the degradation of call quality caused by the < RTI ID = 0.0 >

Method according to the present invention for achieving the above object,

In the case of interworking calls during the exchange period, a method for transmitting and receiving voice data,

The calling party's mobile switching center checks the service option of the subscriber, and if the communication results with the mobile subscriber, inserts the F-IE parameter information that determines the codec bypass in the part of the ISUP message, and then sends the ISUP message to the power station. A message transmission process for transmitting the message;

The large station receiving the ISUP message may be configured to check the F-IE parameter of the ISUP message to convert the local call processing block into the bypass mode in the codec bypass mode.

1 is a communication diagram between a cellular phone and a wired subscriber in a typical digital cellular system,

2 is a relational diagram of transmission and reception between cellular phones in a typical digital cellular system,

3 is a schematic configuration diagram illustrating a relationship between ISUP message transmission and reception during a mobile communication exchange period to which the present invention is applied;

4 is a flowchart illustrating a codec bypass method of a mobile communication switch according to the present invention;

(a) is a flowchart showing a method of transmitting an ISUP message,

(b) is a flowchart showing a method of receiving an ISUP message.

<Explanation of symbols for the main parts of the drawings>

20: Local exchange

30: power exchange

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

Figure 3 is a schematic diagram of a system for explaining a method of transmitting and receiving data during a mobile communication switching period to which the present invention is applied.

Here, reference numeral 20 denotes a local exchange that transmits an ISUP message to the counterpart side and receives the ISUP message transmitted from the counterpart and switches the codec of the own station to bypass mode, and 30 denotes a transmission and reception of an ISUP message with the local exchange 20. And a large exchange that performs the same function as the local exchange 20.

Here, the ISUP message is an ISDN user part message, which is the first message transmitted to the counterpart exchange when establishing a call in the exchange period.

4 is a flowchart illustrating a codec bypass method of a mobile communication switch according to the present invention, (a) is a flowchart illustrating a method of transmitting an ISUP message, and (b) is a flowchart illustrating a method of receiving an ISUP message.

Hereinafter, the codec bypass method of the mobile communication switch according to the present invention will be described in detail with reference to FIGS. 3 and 4.

First, the concept of the codec bypass method of the mobile communication exchange according to the present invention will be briefly described for the convenience of the overall description of the present invention.

In case of interworking call during exchange period, it is possible to transmit information called service option between subscribers in ISUP message when setting up call so that call service can be established by bypassing voice data without transcoding mutually if service option of calling subscriber and receiving subscriber is same. Only when the service options are not the same, mutual transcoding is used to set up the call. In particular, it allows conversion to transcoding mode during operation in bypass mode if necessary. To do this, the service option, which is the corresponding information, can be delivered when the call is set up during the exchange period.

Hereinafter, the present invention will be described in detail with reference to these concepts.

First, in order to transfer service option information of a mobile terminal during call setup of a mobile (mobile terminal) to mobile (mobile terminal) period, a parameter of Facility I. E is added to some messages of the ISUP message.

Table 1-1 below shows an ISUP message when Facility I.E is added to an ISUP message.

In this case, Mode is used to transmit information on the call of the own station to the counterpart mobile station to determine whether it is Bypass / transcode. If Mode is "1", it indicates the bypass mode, and if it is "0", it indicates the transcoding mode.

The service options are as shown in Table <1-2>.

Bit (3-0) information Service options 0 0 0 0 Reserved 0 0 0 1 Basic Variable Rate Voice Service (8kbps) 0 0 1 0 Mobile Station Loopback (8kbps) 0 0 1 1 Enhanced Variable Rate Voice Service 0 1 0 0 Asynchronous Data Srevice 0 1 0 1 Group 3 Facismile 0 1 1 0 Short message services 0 1 1 1 Packet Data Service: Internet or ISO Stack 1 0 0 0 Packet Data Service: CDPD Protocol Stack 1 0 0 1 Mobile Station Loopback (13 kbps) 1 0 1 0 STU-III Service Option 1100-1111 Reserved

Looking at the method of transmitting the above-described ISUP message as follows.

As shown in Fig. 4A, in the trunk call No. 7 (TC7) which is an ISUP relay call processing block in the local exchange 20, an initial address message (IAM), a response message (ANM), and a parity request message (FAR). In case of transmission, check the service option of the subscriber and convert the information (Mode) to the F-IE parameter in the ISUP message ("1" in the bypass mode, "0" in the transcoding mode), and set ( ST1-ST3), ISUP message is sent to the power exchange 30.

On the other hand, when receiving the ISUP message at the switching center 30, as shown in Figure 4b, by checking the F-IE parameter in the received ISUP message (ST5-ST6), and converts the service option information of the subscriber ( ST7), the information is transmitted to the originating / receiving call processing block in the own station so that the codec operates in the bypass mode or the transcoding mode (ST8).

That is, if the F-IE parameter is set to "0", the originating / incoming call processing block operates in the transcoding mode. If the F-IE parameter is set to "1", the originating / incoming call processing block Operate in this bypass mode.

In this case, the first exchange 30 transmits the ISUP message to the local exchange 20 first, and operates in the same manner as described above, and only the local exchange 30 transmits the ISUP message while the local exchange 20 transmits the ISUP message. Only the operation to receive the ISUP message will be converted.

In addition, there is a case where the F-IE is not applied to the ISUP message as described above.

When establishing a call between a mobile-to-land (wired subscriber) or a land-to-mobile, all relays interworking with R2, ISDN No. 7

As described above, in the present invention, when the interworking call of the exchange period is inserted, the call between the terminals having the same service option is inserted into the ISUP message, and transmitted to the counterpart side exchange when the call is set up. Can be operated in bypass mode, thereby preventing the conventional double transcoding in advance.

In addition, due to the prevention of the double transcoding as described above there is an effect that can prevent the degradation of the call sound quality.

Claims (2)

In the case of interworking calls during the exchange period, a method for transmitting and receiving voice data, The calling party's mobile switching center checks the service option of the subscriber, and if the communication results with the mobile subscriber, inserts the F-IE parameter information that determines the codec bypass in the part of the ISUP message, and then sends the ISUP message to the power station. A message transmission process for transmitting the message; The mobile station receiving the ISUP message includes a message receiving process of checking the F-IE parameter of the ISUP message to switch the local call processing block to the bypass mode in the codec bypass mode. Codec bypass method. The codec bypass method of claim 1, wherein the F-IE parameter information is set to "1" in the bypass mode and to "0" in the transcoding mode. .