CN101365189B

CN101365189B - Method and system implementing speech passing through in mobile network

Info

Publication number: CN101365189B
Application number: CN2008101465462A
Authority: CN
Inventors: 林奕琳; 李宝荣; 杨维忠; 孙宇; 张琳峰; 龙彪; 林衡华; 肖海
Original assignee: China Telecom Corp Ltd
Current assignee: China Telecom Corp Ltd
Priority date: 2008-09-02
Filing date: 2008-09-02
Publication date: 2011-07-27
Anticipated expiration: 2028-09-02
Also published as: CN101365189A

Abstract

The invention discloses a method and a system for realizing the transparent transmission of the speech in the network. BSS at the home end receives a switching command of the speech transparent transmission service, and a core network media processing node determines the load manner of the interface between the processing node and the BSS; if the load manner is TDM, the ISLP adaptation is carried out to the transparent transmission speech stream and the formed media stream is transmitted; if the load manner is IP-load, the speech stream to be transparently transmitted is packaged into an RTP bag in a message manner and the special field is filled in the RTP extension header and the formed media stream is transmitted. The media load manner of the core network media processing node determines the incoming and outcoming load manners of the media stream, and detects ISLP special mark or the RTP-header special extended field, if detected, determining whether the media adaptation is required; and if not required, the media stream is transmitted from the incoming local; if required, the media stream is transmitted without coding and decoding transformation through adaptation. BBS at the opposite end receives the media stream, and processing according to the interface media load manner of the core network.

Description

Method and system for realizing voice transparent transmission in mobile network

Technical Field

The present invention relates to the field of mobile communication technology, and in particular, to a method and system for implementing voice transparent transmission in a mobile network.

Background

In a conventional CDMA (code division multiple access) mobile communication network, a core network adopts a circuit switching technology based on TDM (time division multiplexing), and a current CDMA network architecture is shown in fig. 1. When the terminals of both communication parties use the EVRC (enhanced variable rate coding) voice coding of 8K, the BSS needs to convert the voice from EVRC coding of 8K rate to PCM coding of 64K rate, or from PCM of 64K to EVRC coding of 8K (if other voice coding is used by the handset, conversion from other voice coding to PCM coding needs to be performed). The disadvantages of this conversion are firstly a reduced speech quality and secondly a waste of vocoder resources. To solve this problem, the vocoder can be replaced with ISLP (inter-system interconnection protocol) in the CDMA standard. ISLP is an internetwork interconnection protocol in a CDMA network, and completes the adaptation of packet side data to TDM side 64K data in an asynchronous mode, wherein the specific adaptation mainly comprises the following steps: (1) inserting '0' into continuous 5 '1's in EVRC voice code stream; (2) performing frame sealing treatment on the data inserted with the '0' by using '01111110 (0x 7E)' as a frame head and a frame tail; (3) and adopting 0x7E as a synchronization mark for the framed data, filling a data gap after framing with '0 x 7E', adapting to a 64K code stream, and transmitting in a TDM link. And the ISLP inverse adaptation is a process of adapting 64K PCM code streams into original data. The detailed ISLP processing can be seen in TIA/EIA PN-3660.

With the development of mobile communication technology, the CDMA core network has evolved to an all-IP (internet protocol) network, and has now entered the lmsd (legacy MS domain) stage. The MSC is separated into two parts of MSCe (mobile switching center emulation) and MGW (media gateway), realizing the separation of control and bearing. Meanwhile, the TDM circuit switching technology will be replaced by the packet network technology, and voice transmission gradually realizes IP.

Due to the IP of voice transmission, the network introduces voice compression coding and decoding, and in CDMA network, commonly used are voice coding and decoding algorithms such as EVRC and QCELP13K (13K high-pass code excited linear prediction), and voice subjected to ISLP adaptation in BSS must bypass a vocoder when passing through an IP media transmission unit, otherwise normal communication cannot be realized. Therefore, when the voice stream to be transparently transmitted is transmitted through part of or all of the IP in the network, a method and a system are needed to implement transparent transmission of the voice stream to be transparently transmitted, so as to implement normal voice transparent transmission communication.

Disclosure of Invention

In view of this, the present invention provides a method and a system for implementing voice transparent transmission in a mobile network, which implement normal voice transparent transmission communication when a voice stream passes through partial IP transmission or full IP transmission in the network.

Based on the above object, the present invention provides a method for implementing voice transparent transmission in a mobile network, which is applied to a system including a base station subsystem BSS, a core network media processing node and a communication terminal MS, and comprises:

s1, after the local BSS receives the MS service indication message which converts the common voice service into the voice transparent transmission service, the vocoder stops encoding and decoding the voice, judges the bearing mode of the interface between the local BSS and the core network media processing node, if the bearing mode is time division multiplexing TDM bearing, the inter-system interconnection protocol ISLP adaptation is carried out on the voice stream to be transparent transmission, and the formed media stream is transmitted to the core network media processing node through TDM; if the packet is an Internet Protocol (IP) bearer, the voice code stream to be transparently transmitted is packaged in a real-time transport protocol (RTP) packet in a message mode, a special field is filled in an RTP extension head, and the formed media stream is transmitted to a core network media processing node through an IP;

s2, after receiving the media flow, the core network media processing node judges the media load-bearing mode of the incoming and outgoing of the media flow, and detects the ISLP special mark or the special extension field of RTP head, if it detects the ISLP special mark or the special extension field of RTP head, it judges whether to carry on the media adaptation, if it does not need to adapt, it directly transmits the media flow from the incoming to the outgoing, if it needs to adapt, it does not carry on the encoding and decoding conversion transmission outgoing after adapting the media flow;

and S3, after the BSS at the opposite terminal receives the media stream and receives the service indication message of the MS converting the common voice service into the voice transparent transmission service, corresponding processing is carried out according to the interface media bearing mode of the opposite terminal and the core network.

Optionally, in step S1, the padding of the special field in the RTP extension header is to set the X flag of the RTP header to 1 and pad a special extension field indicating a speech stream that has not undergone ISLP adaptation or pad a special extension field indicating a speech stream that has undergone ISLP adaptation.

Optionally, the step S2 of the method further includes:

s201, when the incoming and outgoing of the media stream are TDM media bearing mode, if the core network media processing node detects ISLP special mark, the media stream is directly transmitted from the incoming to the outgoing.

Optionally, the step S2 of the method further includes:

s202, when the incoming and outgoing of the media stream are both IP media bearing mode, if the core network media processing node detects that the extension of the RTP header is a special field, the media stream is directly transmitted from the incoming to the outgoing.

Optionally, in step S202 of the method, when the core network media processing node detects the special RTP extension header, the core network media processing node further turns off a vocoder, and/or turns off a voice enhancement function for a media stream; and then the media stream is directly transmitted from the incoming to the outgoing.

Optionally, the step S2 of the method further includes:

s203, when the incoming of the media stream is TDM media load and the outgoing is IP media load, if the core network media processing node detects the special mark of ISLP, it judges if the outgoing IP load of the core network media processing node supports voice compression coding, if it does not support, it directly encapsulates the TDM media stream in RTP to transmit outgoing, and marks the RTP head X at position 1, and uses special head extension field to indicate that the RTP packet contains ISLP adapted media stream; if yes, after ISLP reverse processing is carried out on the TDM media stream, the TDM media stream is encapsulated in RTP for transmitting outgoing, the mark position of RTP head X is set to be 1, and special head extension field is used for indicating that the media stream in RTP message is not subjected to ISLP adaptation.

Optionally, the step S2 of the method further includes:

s204, when the incoming of the media stream is IP media bearing and the outgoing is TDM media bearing, if the core network media processing node detects that the extension head of the RTP is a special field which shows that the extension head is not subjected to ISLP adaptation, the ISLP adaptation is carried out, and the obtained media stream is transmitted to the outgoing.

Optionally, the ISLP is adapted to adapt the voice stream to a 64Kbit/s media stream.

Optionally, the step S2 of the method further includes:

s205, when the incoming of the media stream is IP media bearing and the outgoing is TDM media bearing mode, the core network media processing node needs to detect the RTP extension head, if the detected RTP extension head is the special field which indicates the ISLP adaptation, the 64kbit/S media stream in the RTP is transmitted to the outgoing.

Optionally, in step S3, the performing different processing according to the bearer mode of the interface with the core network media processing node further includes: determining the media bearing mode of the interface between the BSS and the core network media processing node,

if the mode is TDM, then making ISLP adaptive inverse process, and transmitting the adaptive original voice flow to MS;

if the method is an IP mode, the extension header of the RTP is detected to be a special field which shows that ISLP adaptation is not carried out, and the voice stream in the RTP message is directly transmitted to the communication terminal.

Optionally, in the method, the core network media processing node is a Media Gateway (MGW) or a Mobile Switching Center (MSC).

Optionally, the inverse process of the ISLP adaptation in this method is to adapt a 64kbit/s speech stream to the original speech stream.

In order to achieve the above object, the present invention further provides a system for implementing voice transparent transmission in a mobile network based on the above method, where the system includes:

the communication terminal MS is used for sending a voice transparent transmission service switching instruction to the base station system;

the base station subsystem BSS comprises a local terminal BSS and an opposite terminal BSS, wherein the local terminal BSS is used for receiving the voice transparent transmission service switching instruction and judging whether inter-system interconnection protocol ISLP adaptation is carried out or not and whether a special field is filled in a real-time transport protocol RTP extension head or not according to a media bearing mode of a core network media processing node interface; the opposite terminal base station is used for receiving the voice transparent transmission service switching instruction and carrying out corresponding processing according to a media bearing mode of a core network media processing node interface;

the core network media processing node is used for judging whether to detect the ISLP special mark and whether to detect the special extension field of the RTP head according to the incoming and outgoing media carrying modes of the media stream, judging whether to carry out media adaptation if the ISLP special mark or the special extension field of the RTP head is detected, directly transmitting the media stream from the incoming to the outgoing if adaptation is not needed, and not carrying out coding and decoding conversion to the outgoing after the adaptation if adaptation is needed.

From the above description, it can be seen that the present invention provides a method and system for implementing voice transparent transmission in a mobile network. The method comprises the steps that a voice transparent transmission service mark is detected through BSS, recognition of voice transparent transmission communication service is achieved, and meanwhile, according to an interface media bearing mode of a core network media processing node, whether ISLP adaptation is carried out or a special field (local terminal BSS) is filled in an RTP (real-time transport protocol) extension head or whether ISLP inverse adaptation is carried out or an RTP extension head (opposite terminal BSS) is detected and corresponding adaptation is carried out according to the extension head is judged; the core network media processing node realizes the recognition of the voice transparent transmission service by detecting ISLP special mark (TDM side) and/or RTP extension head special field (IP side), and adapts the current bearing mode to the mode that the voice transparent transmission service can transmit. According to the operations of the BSS and the core network media processing node, the problem of voice transparent transmission in different bearing environments is solved. Therefore, the voice can be transmitted on different media, and the voice transmission service can be normally carried out. Thereby enabling voice transparent traffic to accommodate different bearers rather than just TDM.

Drawings

Fig. 1 is a schematic diagram of a prior art CDMA network architecture;

FIG. 2 is a schematic structural diagram of a system for implementing transparent transmission of voice in a network according to an embodiment of the present invention;

FIG. 3 is a flowchart of a method for implementing transparent voice transmission in a network according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a system structure of a TDM transmission scenario between a BSS and a core network media processing node, and an IP transmission scenario between the core network media processing node and the core network media processing node according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a system structure of an IP transmission scenario between an RSS and a core network media processing node, and a TDM transmission scenario between the core network media processing node and the core network media processing node according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a system in which IP transmission scenes are set between a BSS and a core network media processing node, and between the core network media processing node and the core network media processing node according to the embodiment of the present invention.

Fig. 7 is a schematic system structure diagram of an IP transmission scenario between the BSS1 and the core network media processing node, a TDM transmission scenario between the core network media processing node and the core network media processing node, and a TDM transmission scenario between the core network media processing node and the BSS2 according to the embodiment of the present invention;

fig. 8 is a schematic diagram of a system structure of a TDM transmission scenario between a BSS1 and a core network media processing node, a TDM transmission scenario between a core network media processing node and a core network media processing node, and an IP transmission scenario between a core network media processing node and a BSS2 according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the invention realizes the recognition of the voice transparent transmission service by detecting the special service mark of the voice transparent transmission service through the BSS. Meanwhile, according to the interface media bearing mode of the BSS and the core network media processing node, judging whether to carry out ISLP adaptation or fill a special field (local end) in an RTP (real-time transport protocol) extension head; and the BSS performs corresponding processing according to the interface media bearing mode of the opposite terminal and the core network. Meanwhile, the core network media processing node realizes the recognition of the voice transparent transmission service by detecting an ISLP special mark (TDM side) and/or an RTP head extension special field (IP side), and adapts the current bearing mode to a mode in which the voice transparent transmission service can be transmitted.

According to the operations of the BSS and the core network media processing node, the problem of voice transparent transmission under different bearing environments is solved, and therefore voice transparent transmission can be achieved no matter whether the bearing of the media unit passing through the network is TDM or IP.

Referring to fig. 3, the present invention provides a method for implementing transparent voice transmission in a network, which is applied to a system including a BSS (base station subsystem), a core network media processing node, and an MS (communication terminal). The BSS includes a home BSS and an opposite BSS, which may be different physical entities.

The method comprises the following core steps:

step S1, after the local BSS receives the MS service indication message which converts the common voice communication into voice transmission, the vocoder stops processing the voice coding and decoding, judges the bearing mode of the interface between the local BSS and the core network media processing node, and further judges whether ISLP adaptation is carried out (S101) or the ISLP adaptation is carried out or the ISLP adaptation is encapsulated in an RTP packet in a message mode, and a special extension field is filled in an RTP header X mark position 1 (S102); the voice media is then delivered to the core network media processing node.

In step S1, when the interface between the local BSS and the core network media processing node is a TDM bearer, step S101 is executed: the BSS of the local terminal starts an ISLP adaptation program, adapts the voice stream to be transparently transmitted into a 64Kbit/s media stream and transmits the media stream to the core network media processing node through TDM.

When the interface between the local BSS and the core network media processing node is an IP bearer, step S102 is executed: BSS encapsulates the voice code stream to be transmitted in RTP packet and transmits it to the core network media processing node, and sets the mark bit of RTP head X to 1, at the same time, the RTP head uses special expansion field (such as 0xA001) to represent the voice media stream which is not adaptive by ISLP, and transmits it to the core network media processing node through IP.

Step S2, after receiving the media stream sent by BSS, the core network media processing node determines the incoming and outgoing media carrying manners of the media stream, and further determines whether to detect the ISLP special flag, and whether to detect the special extension field of the RTP header, if the ISLP special flag (e.g. 0x7E, after the general BSS performs ISLP adaptation, there is a "0 x 7E" special flag) or the RTP header special extension field is detected, then the vocoder is turned off (if the vocoder is turned on before the voice stream with the special flag or the RTP header extension field is received, the vocoder needs to be turned off, if not, then it does not need to be turned off), and at the same time, determines whether to perform media adaptation, if the incoming does not need to directly pass the media stream from the outgoing office, if the adaptation is needed, then the media is not passed through the outgoing office after being adapted.

In step S2, the method further includes:

step S201, when the incoming and outgoing of the media stream are TDM media bearing mode, the core network media processing node detects ISLP special mark, then closes all media processing operation, and directly transmits the media stream from the incoming to the outgoing; if not, the process is carried out according to the common flow.

Step S202, when the incoming and outgoing of the media stream are both IP media bearing mode, the core network media processing node detects RTP header expansion, if the expansion of RTP header is detected to be special field (such as 0xA001 or 0xA002), the media stream is directly transmitted from incoming to outgoing; if not, the process is carried out according to the common flow. If the core network media processing node detects the special RTP header extension, the core network media processing node closes a voice coder and/or closes a voice enhancement function of the media stream; and then the media stream is directly transmitted from the incoming to the outgoing.

Step S203, when the incoming of the media stream is TDM media bearer and the outgoing is IP media bearer, the core network media processing node needs to detect the ISLP special flag, and if not, processes according to the normal flow. If the special mark of the ISLP is detected, different processing is carried out according to the coding and decoding type supported by the outgoing IP bearer of the media processing node of the core network, and the method specifically comprises the following steps:

judging whether the outgoing IP bearer of the core network media processing node supports the voice compression coding, if not, executing the step S203 a; if so, step S203b is executed.

Step S203a, directly encapsulate the TDM media stream in RTP for transmission outgoing, and mark position 1 with RTP header X, where the RTP header indicates that the media stream contained in the RTP packet is ISLP-adapted with a special header extension field (e.g. 0X A002).

Step S203b, after performing ISLP reverse processing on the TDM media stream, encapsulating the TDM media stream in RTP for transmission outgoing, setting the flag position of RTP header X to 1, and using a special header extension field (e.g. 0xA001) to indicate that the media stream in the RTP packet has not undergone ISLP adaptation.

When the incoming of the media stream is an IP media bearer and the outgoing is a TDM media bearer, step S2 further includes:

the core network media processing node detects the RTP head and the extension head, if the special head extension field is not detected, the processing is carried out according to the common flow; if so, stopping the processing of the media stream by the vocoder and the like, and judging whether the special header extension field indicates that the media stream has undergone ISLP adaptation, if so, executing step S205, otherwise, executing step S204.

Step S204, if the expansion header of the RTP is detected to be a special field (such as 0xA001) indicating that ISLP adaptation is not performed, ISLP adaptation is required, and a voice stream in the RTP is adapted to be a media stream of 64kbit/S and transmitted out through the TDM link.

If the extension header of the RTP is detected to be a special field (e.g. 0xA002) indicating that ISLP adaptation has been performed, the 64kbit/S media stream in the RTP is directly transmitted out through the TDM link in step S205.

After the step S2 is finished, if the next network node where the outgoing media stream enters is the BSS, the method proceeds to step S3; if the next network node into which the outgoing media stream enters is the core network media processing node, it is still performed according to the step of step S2 described above.

Step S3, after the BSS receives the media stream, and the BSS further receives the service indication message sent by the MS to convert the normal voice into the voice transparent transmission service, the BSS stops the processing of the vocoder to encode and decode the voice, and performs different processing according to the bearer mode of the interface of the core network media processing node, which specifically includes:

judging the media bearing mode of the interface of the opposite terminal BSS and the core network media processing node, if the media bearing mode is TDM mode, executing step S301; if the IP mode is adopted, step S302 is executed.

Step S301, the BSS at the opposite end performs the inverse process of ISLP adaptation, and adapts the TDM voice stream of 64kbit/S to the voice stream sent by the communication terminal at the sending end and transmits the voice stream to the receiving communication terminal.

Step S302, if the BSS of the opposite end detects the RTP extension header, determining whether the special field indicates that the media stream has undergone ISLP adaptation, and if the special field indicates that the special field has not undergone ISLP adaptation (e.g. 0xA001), directly transmitting the voice stream in the RTP packet to the communication terminal. The invention also provides a system for realizing the voice transparent transmission by the network after switching from the common voice to the voice transparent transmission communication, which mainly comprises:

the communication terminal 201 is configured to send a voice transparent transmission service switching instruction to the base station system;

the base station subsystem 202 comprises a local terminal base station subsystem and an opposite terminal base station subsystem, wherein the local terminal base station subsystem is used for receiving the voice transparent transmission service switching instruction and judging whether to perform ISLP adaptation or not and whether to fill special fields in an RTP (real time protocol) expansion head or not according to a media bearing mode of a media processing node interface of a core network; the opposite terminal base station subsystem is used for judging whether to detect ISLP special mark and RTP extension head according to the media bearing mode of the media processing node interface of the core network, judging whether to perform ISLP adaptation inverse process, and transmitting the adapted or unadapted media stream to the communication terminal

The core network media processing node 203 is configured to determine whether to detect an ISLP special flag, whether to detect a special extension field of an RTP header, and if the ISLP special flag or the RTP header special extension field is detected, turn off a vocoder, and determine whether to perform media adaptation, and if adaptation is not needed, directly pass the media stream from the incoming to the outgoing, and if adaptation is needed, not perform codec conversion to the outgoing after the adaptation.

The following detailed description is given by way of example in conjunction with the accompanying drawings.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a system for implementing transparent transmission of voice in a network according to the present invention. The system is preferably a CDMA network system, comprising at least: communication terminal 201, base station subsystem 202, core network media processing node 203. Wherein,

the communication terminal 201 is configured to send a voice transparent transmission service switching instruction to the base station subsystem;

a base station subsystem 202, including a home base station and an opposite base station, where the home base station is configured to receive the voice transparent transmission service switching instruction, and determine whether to perform ISLP adaptation or fill a special field in an RTP extension header according to a media bearer mode of a media processing node interface of a core network; the opposite terminal base station subsystem is used for judging whether to detect ISLP special mark and RTP extension head according to the media bearing mode of the media processing node interface of the core network, judging whether to perform ISLP adaptation inverse process, and transmitting the adapted or unadapted media stream to the communication terminal

In this embodiment of the present invention, the core network media processing node may be an MSC (mobile switching center) of a circuit switching core network or an MGW (media gateway) of a soft switching core network.

The following describes a scheme for implementing voice transparent transmission in different network media bearer manners by using a specific embodiment, in which an MGW is used as the core network media processing node in the following embodiment.

The first embodiment is as follows: the BSS and the MGW transmit via TDM, and the MGW implement IP transmission, as shown in fig. 4.

After the BSS1 receives the instruction message of the communication terminal converting from the common voice communication to the voice transparent transmission communication, the coding and decoding processing program of the voice by the vocoder is stopped, the ISLP adaptation is carried out because the load of the interface with the MGW1 is a TDM load mode, and the adapted voice media is transmitted to the MGW 1;

based on incoming TDM transmission, MGW1 detects ISLP special mark to find the media is ISLP adapted voice, then it does not carry out coding, marks RTP head X as position 1, and uses special field (such as 0xA002) to represent the ISLP adapted voice media flow in RTP extended head, and encapsulates the media flow in RTP to transmit out.

MGW2 is incoming IP media bearer and outgoing TDM media bearer, so detecting the incoming RTP extension header, detecting that the extension header of RTP is a special field (e.g. 0xA002) indicating that ISLP adaptation has been performed, and then transparently transmitting the voice stream in RTP out using TDM bearer.

The media stream received by the BSS2 is TDM-loaded, so that ISLP special mark detection is enabled, after detecting the ISLP special mark, the reverse process of ISLP adaptation is performed, and a 64kbit/s voice stream is adapted to an original voice stream and transmitted to the communication terminal.

Example two: it is assumed that the BSS and the MGW are transmitted through IP, and the MGW are transmitted through TDM, which is shown in fig. 5.

After the BSS1 receives the command message of the communication terminal to convert from the normal voice communication to the voice transparent transmission communication, the vocoder stops encoding and decoding processing program of voice, because the bearer with the MGW1 interface is an IP bearer, the voice code stream is encapsulated in the RTP and transmitted to the MGW1, and at the same time, the RTP header X marks the position 1, and the special field (such as 0xA001) in the RTP extension header indicates that the media stream borne by the RTP is the voice media stream which is not subjected to ISLP adaptation.

The MGW1 performs ISLP adaptation to adapt the voice stream in RTP to a 64kbit/s media stream delivery egress according to the incoming IP media bearer and the outgoing TDM media bearer, detecting the incoming RTP extension header, detecting that the extension header of RTP is a special field (e.g. 0xA001) indicating that the media stream has not undergone ISLP adaptation.

MGW2 detects ISLP special mark to find the media is voice which is adaptive by ISLP, then it does not carry on coding and decoding, if MGW2 outgoing IP bearing supports voice compression coding, then it carries on ISLP inverse process, encapsulates the processed voice code stream in RTP to transmit outgoing, and marks the position of RTP head X as 1, at the same time, the RTP extended head uses special field (such as 0xA001) to represent the carried media stream as voice code stream which is not adaptive by ISLP.

The BSS2 receives the media stream as an IP bearer, enables RTP extension header detection, detects that the extension header of the RTP is a special field (e.g. 0xA001) indicating that ISLP adaptation is not performed, and directly transmits the voice stream in the RTP packet to the communication terminal.

Example three: it is assumed that IP transmission is performed between BSS and MGW and between MGW and MGW, as shown in fig. 6.

After BSS1 receives the instruction message of the communication terminal converting from normal voice communication to voice transmission communication, it stops the vocoder encoding and decoding process to voice, because the bearer with MGW1 interface is IP bearer, encapsulates the voice code stream in RTP and transmits it to MGW1, and marks RTP head X as position 1, and uses special field (such as 0xA001) in RTP extended head to represent the carried media stream as voice code stream without ISLP adaptation.

Since both incoming and outgoing of MGW1 are IP media bearer, MGW1 detects the RTP extension header, which is found to be a special field (e.g., 0xA001) indicating that ISLP adaptation is not performed, thereby passing the media stream directly out from the incoming.

Since both incoming and outgoing of MGW2 are IP media bearer, MGW2 detects the RTP extension header, which is found to be a special field (e.g., 0xA001) indicating that ISLP adaptation is not performed, thereby passing the media stream directly out from the incoming.

The media stream received by BSS2 is an IP bearer, RTP extension header detection is enabled, and if the extension header of RTP is detected to be a special field (e.g. 0xA001) indicating that ISLP adaptation is not performed, voice encoding and decoding are not performed, and voice is directly transmitted to the communication terminal.

Example four: it is assumed that the BSS1 and the core network media processing node MGW1 are in IP transmission, TDM transmission is performed between the core network media processing node MGW1 and the core network media processing node MSC2, and a TDM transmission scenario is performed between the core network media processing node MSC2 and the BSS2, which is shown in fig. 7.

MSC2 performs ISLP specific flag detection if both incoming and outgoing media are TDM bearers, and turns off all media processing operations to pass the media stream out directly from the incoming if an ISLP specific flag is detected.

Example five: it is assumed that BSS1 and MSC1 transmit via TDM, MSC1 and MGW2 transmit via TDM, and MGW2 and BSS2 transmit via IP, as shown in fig. 8.

After the BSS1 receives the instruction message that the communication terminal is switched from the normal voice communication to the voice transparent transmission communication, the vocoder stops the voice encoding and decoding processing program, because the bearer with the MSC1 interface is in the TDM manner, the ISLP adaptation is performed, and the adapted voice media is transmitted to the MSC 1;

MSC1 performs ISLP specific flag detection if both incoming and outgoing media are TDM bearers, and turns off all media processing operations to pass the media stream out directly from the incoming if an ISLP specific flag is detected.

To sum up, the present invention detects the special service mark of the voice transparent transmission service through the BSS, realizes the recognition of the voice transparent transmission service, and simultaneously judges whether to perform ISLP adaptation or fill a special field in the RTP extension header (local BSS) according to the interface media bearing mode with the core network media processing node, or judges whether to detect the ISLP special mark, whether to detect the RTP extension header (opposite BSS), and performs corresponding adaptation according to the need; the core network media processing node realizes the recognition of the voice transparent transmission service by detecting ISLP special mark (TDM side) and/or RTP extension head special field (IP side), and adapts the current bearing mode to the mode that the voice transparent transmission service can transmit. According to the operations of the BSS and the core network media processing node, the problem of voice transparent transmission in different bearing environments is solved. Therefore, the voice can be transmitted on different media, and the voice transmission communication can be carried out normally.

Of course, the invention is capable of other embodiments. Various modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for realizing voice transparent transmission in a mobile network is applied to a system comprising a base station subsystem BSS, a core network media processing node and a communication terminal MS, and is characterized by comprising the following steps:

s1, after the local BSS receives the MS service indication message which converts the common voice service into the voice transparent transmission service, the vocoder stops encoding and decoding the voice, judges the bearing mode of the interface between the local BSS and the core network media processing node, if the bearing mode is time division multiplexing TDM bearing, the inter-system interconnection protocol ISLP adaptation is carried out on the voice stream to be transparent transmission, and the formed media stream is transmitted to the core network media processing node through TDM; if the voice stream is loaded by the Internet Protocol (IP), the voice stream to be transparently transmitted is packaged in a real-time transport protocol (RTP) packet in a message mode, a special field is filled in an RTP extension head, and the formed media stream is transmitted to a core network media processing node through the IP;

s2, after receiving the media flow, the core network media processing node judges the media load-bearing mode of the incoming and outgoing of the media flow, and detects the special ISLP sign or the special field of RTP head, if it detects the ISLP sign or the special field of RTP head, it judges if the media adaptation is carried out, if it does not need adaptation, the media flow is transmitted from the incoming to the outgoing directly, if it needs adaptation, the media flow is not transmitted from the outgoing after adaptation;

and S3, after the BSS at the opposite terminal receives the media stream and receives the service indication message of the MS converting the common voice service into the voice transparent transmission service, processing according to the interface media bearing mode of the opposite terminal and the core network.

2. The method according to claim 1, wherein the padding special fields in the RTP extension header in step S1 is to set the X flag bit of the RTP header to 1 and to pad special fields indicating voice streams that have not undergone ISLP adaptation or to pad special fields indicating voice streams that have undergone ISLP adaptation.

3. The method according to claim 1, wherein the step S2 further comprises:

4. The method according to claim 1, wherein the step S2 further comprises:

s202, when the incoming and outgoing of the media stream are both IP media bearing mode, if the core network media processing node detects the special field of RTP header, the media stream is directly transmitted from the incoming to the outgoing.

5. The method according to claim 4, wherein in step S202, when the core network media processing node detects the special RTP extension header, the core network media processing node also turns off a vocoder and/or turns off a voice enhancement function for the media stream; and then the media stream is directly transmitted from the incoming to the outgoing.

6. The method according to claim 1, wherein the step S2 further comprises:

s203, when the incoming of the media stream is TDM media load and the outgoing is IP media load, if the core network media processing node detects the special mark of ISLP, it judges if the outgoing IP load of the core network media processing node supports voice compression coding, if it does not support, it directly encapsulates the TDM media stream in RTP to transmit outgoing, and marks the RTP head X at position 1, and uses special field to represent the media stream contained in RTP packet which is adaptive to ISLP; if yes, after ISLP reverse processing is carried out on the TDM media stream, the TDM media stream is packaged in RTP for transmission outgoing, the mark position of RTP head X is set to be 1, and special fields are used for indicating that the media stream in RTP messages is not subjected to ISLP adaptation.

7. The method according to claim 1, wherein the step S2 further comprises:

8. The method according to claim 1 or 7, wherein the ISLP is adapted to adapt a speech stream to a 64Kbit/s media stream.

9. The method according to claim 1, wherein the step S2 further comprises:

10. The method according to claim 1, wherein the processing according to the interface media bearer between the peer end and the core network at step S3 further comprises: determining the media bearing mode of the interface between the BSS and the core network media processing node,

11. The method of claim 1, wherein the core network media processing node is a Media Gateway (MGW) or a Mobile Switching Center (MSC).

12. The method of claim 10, wherein the inverse of the ISLP adaptation is to adapt a 64kbit/s speech stream to the original speech stream.

13. A system for implementing the method according to any one of claims 1 to 12, wherein the system comprises:

the communication terminal MS is used for sending a voice transparent transmission service switching instruction to the base station subsystem BSS;

the BSS comprises a local BSS and an opposite BSS, wherein the local BSS is used for receiving the voice transparent transmission service switching instruction and judging whether inter-system interconnection protocol ISLP adaptation is carried out or not and whether a special field is filled in a real-time transport protocol (RTP) extension head or not according to a media bearing mode of a core network media processing node interface; the opposite terminal BSS is used for receiving the voice transparent transmission service switching instruction and processing the voice transparent transmission service switching instruction according to a media bearing mode of a media processing node interface of a core network;

the core network media processing node is used for judging whether to detect the ISLP special mark and whether to detect the special field of the RTP head according to the incoming and outgoing media carrying modes of the media stream, judging whether to carry out media adaptation if the ISLP special mark or the special field of the RTP head is detected, directly transmitting the media stream from the incoming to the outgoing if adaptation is not needed, and not carrying out coding and decoding conversion to the outgoing after the adaptation if adaptation is needed.