Method and node for the control of a connection in a communication network

The present invention relates to methods and nodes for controlling connections in a communication network, and in particular to methods and nodes for controlling the choice of payload coding scheme along a wireless or wired connection on a call-by-call basis.

A communication network consists of interconnected nodes and can be divided into a core network and an access network, which is an access network for access to user equipment, such as a mobile user equipment radio access network. Provide wireless access. A core network interconnects an access network with additional networks, such as other core networks or the Internet. In the Universal Mobile Telecommunications System (UMTS) architecture, access networks can be controlled by wireless network controllers (RNCs, Radio Network Controllers), which are connected to the core network. Provides access to the core network. That is, it acts as an access node. Global Mobile Communication System (GSM) In Communications) architecture, the access network can be controlled by a base station controller (BSC). The 3G core network is controlled by one or more mobile switching stations (MSCs, Mobile Switching Centre). These MSCs also influence decisions in RNCs and BSCs.

For transmission over the connection, audio (or other media) is coded (and later decoded) according to one or more coding / decoding schemes. The coding / decoding method is also referred to herein as a coding method, or is referred to as a "codec". Determining the optimal codec or set of codecs may be made by codec negotiation. The coding scheme can carry audio in either compressed or uncompressed mode. In many networks, different encodings can be used, and different nodes can have different capabilities to handle the encodings. Voice transcoders transcode between different voice coding schemes. That is, the transcoder decodes one method into voice (linear PCM or other representation) and then encodes the voice by another method. However, the transcoder may also transcode the audio directly between the coding schemes, without going through an intermediate representation of the audio. Therefore, the transcoder is a device that performs a codec. That is, the transcoder implements a particular coding scheme. (In fact, transcoders can implement multiple coding schemes and can use them on a call-by-call basis at the request of call / session control applications). Tandem Free Operation (TFO) is the configuration of two transcoders with compatible coding schemes on the compressed audio side at both ends of the connection, that is, on the interface to the user device. In this case, transcoding intervals can be avoided and compressed audio coding is used end-to-end in the connection (see 3GPP TS 28.062).

Out of Transcoder Control (OoBTC) allows voice connections to be established end-to-end with a common coding scheme. That is, ideally the same voice coding is used throughout the connection between the access networks. The advantage of this is that maintaining compressed audio saves core network bandwidth and optimizes audio quality, as in principle always avoids distorting transcoding intervals (3GPP TS 23.153). reference).

The International Telecommunication Union (ITU) protocol, called Bearer Independent Call Control (BICC), supports out-of-band signaling procedures, with out-of-band signaling procedures between network nodes. Allows negotiation of coding schemes. In Non-Patent Document 1, the negotiation of the encoding method is the application transport parameter (APP, Application Transport) in the initial address message (IAM, Initial Address Message) for connection setting. By including a list of permissible coding methods in Parameter), it is performed from the outgoing control node of the connection to each subsequent node. Each node examines the list, and if each node does not support a particular coding type, each node excludes that coding type from the list. Any unsupported coding type will be excluded as long as the matched list is communicated with IAM and BICC signaling is supported. When the final node, which is either the incoming node or the last node that supports BICC, is reached, the encoding type is selected by the final node. A list of this selected coding scheme and any remaining coding schemes that are generally supported is returned to the originating node via all intermediate nodes.

In the BICC coding scheme negotiation procedure, how many transcoder intervals are allowed, and the access network that supports out-of-band coding scheme negotiation is transcoding between the access node and the rest of the network. There is no provision to define whether a transcoder can be started to maintain a Transcoder Free Operation (TrFO). The number of transcoding sections in an end-to-end connection can significantly affect voice quality. Four or more transcoding sections usually cause substantial audio degradation. The number of intervals that causes substantial degradation depends on the coding algorithm / method and audio degradation by additional entities in the connection.

Bearer technology in nodes or networks does not support compressed audio, so encoding negotiation procedures may result in transcoders being invoked to enable additional services. For example, an asynchronous transfer mode (ATM) network can transmit both compressed and uncompressed audio, while a synchronous transfer mode (STM) network requires uncompressed audio coding. And. It can include TFO with compressed audio via bit steal (TFO is not much needed in STM). Moreover, it would be desirable for negotiations to result in control of transcoder selection, which is not always the case with current technology.

In many cases, it is necessary to change the coding method in the area of connection. For example, connections often move between different access networks due to handovers. Also in this case, the selection of controlled transcoders is often not achieved.

<p><nplcit num="1"><text>ITU Telecommunications Standardization Division (ITU-T) Proposal BICC Q.1901 (ITU, June 2000)</text></nplcit></p>

<p> Therefore, an object of the present invention is to provide an improved method for controlling the selection of coding schemes used in communication networks.</p>

<p> Therefore, a method for controlling the establishment or modification of a connection to a subscriber with a subscription in a telecommunications network is provided, and this connection is a plurality of supported coding schemes that can affect the quality of the connection. Established or modified between nodes configured to use a coding scheme selected from among. The method provided determines a subscription quality level that indicates a target quality level for the subscriber associated with the subscription, and the node controlling the connection selects the coding scheme used for the connection. Attention is paid to checking the subscription quality level when doing so.</p><p> According to a further aspect of the provided method, a range of permissible degradation values indicating the permissible degradation of the connection to be established or modified is associated with the subscription quality level. A predicted cumulative degradation value indicating the predicted cumulative degradation associated with using the corresponding coding scheme for the connection is determined for at least one of the supported coding schemes and controls the connection. The node selects the coding scheme used so that the value indicating the predicted cumulative degradation value is within the permissible degradation value.</p><p> This is a rigorous way to provide subscription quality levels.</p><p> According to yet another aspect of the provided method, the connection comprises a plurality of connection sections, with a plurality of candidate paths for the concatenation of the coding scheme leading to the current section through one or more preceding sections. The node controlling the connection suffers the expected degradation associated with using any of the one or more preceding interval coding schemes for a particular candidate path among the plurality of candidate paths. The node that receives the indicated degradation value index and controls the connection said that it received in determining the cumulative degradation associated with using the current section coding scheme for the particular candidate path. Use the degradation index.</p><p> This limits the effort required to determine the predicted cumulative degradation and makes the associated calculations easier to handle.</p><p> According to another aspect of the method provided, the received degradation index is a first degradation indicator and the particular candidate path is one or more additional connections following the current coding interval. It has a section. A further degradation value index indicating the predicted degradation associated with using any of the coding schemes for the subsequent section of the particular candidate path is received by the control node and the control node is in the current section. In determining the cumulative degradation of the candidate path associated with using the coding scheme in, the first degradation index and the further degradation index are used.</p><p> This method allows the coding method to be freely selected without depending on a predetermined candidate path.</p><p> According to a further aspect of the provided method, the predicted resource usage of network resources associated with using at least one of the supported coding schemes is determined and the node controlling the connection is , The coding scheme used is selected so that the associated predicted resource usage is minimized.</p><p> As a result, the usage of network resources can be optimized within the range of the subscription quality level.</p><p> As an example, the predicted resource usage of a network resource is the transmission bandwidth required for transmission over an established or established connection according to the coding scheme used.</p><p> As another example, the connection comprises a plurality of connection sections, and the coding method used is the first coding method used for the first connection section and for the second connection section. The second coding method is used, and the predicted resource usage of the network resource is the predicted processing power consumption for transcoding that may occur between the first and second coding methods. is there.</p><p> According to another aspect of the provided method, an indication that the predicted resource usage of the network resource should be minimized is received at the network node controlling the connection. According to this provided aspect, the connection control node examines the display and decides to minimize the resource usage.</p><p> According to one example, the subscription quality level is associated with a subscriber data record.</p><p> According to another example, the subscription quality level is derived from the subscriber's identification information.</p><p> The subscription quality level can be the quality level of the calling subscriber.</p><p> According to one aspect of the method provided, when a list of supported coding schemes that may be used for the connection and is transmitted between the nodes that control the connection is created. The subscription quality level may be examined.</p><p> This method can be easily implemented.</p><p> According to a further aspect, the node controlling the connection determines the subscription quality level of the calling subscriber and the subscription quality level of the called subscriber when selecting the coding scheme used. To find out.</p><p> As a result, both communication partners can influence the selection of the coding method.</p><p> According to a further aspect of the provided method, a first coding scheme is used for the first transmission direction of the connection to be established or modified, and a second of the connections to be established or modified. A second coding method is used with respect to the transmission direction, and the second transmission direction is different from the first transmission direction. The subscription quality level of the calling subscriber is examined when the first coding scheme is selected, and the subscription quality level of the called subscriber is when the second coding scheme is selected. Can be investigated.</p><p> As a result, each subscriber receives data according to the transmission quality for which he / she has a subscription contract.</p><p> Further, according to the teachings of the present invention, a network node for controlling the establishment or modification of a connection to a subscriber having a subscription contract in a communication network is provided. The connection is established or modified between nodes configured to use a coding scheme selected from a plurality of supported coding schemes that may affect the quality of the connection. The provided network node selects a quality level determination unit determined by the subscription quality level, which indicates the target quality level for the subscriber associated with the subscription, and the coding scheme used for the connection. It is noted that the decision includes a processing unit that examines the subscription quality level.</p><p> A preferred embodiment of the provided method is equally applicable with respect to the provided network nodes.</p><p> Further, according to the teachings of the present invention, a program on a data medium that can be read by a network node is provided, and when the program is executed on the network node, the network node is provided with a communication network. , A step of controlling the establishment or modification of a connection to a subscriber with a subscription, said connection being a code selected from a number of supported coding schemes that can affect connection quality. A plurality of steps, a step of establishing or changing between nodes configured to use the conversion method, a step of determining a subscription quality level indicating a target quality level for the subscriber associated with the subscription, and a plurality of steps. In the decision to select the coding method used for the connection from the supported coding methods, it is instructed to perform the step of examining the subscription quality level.</p><p> A preferred embodiment of the provided method is equally applicable with respect to the provided program.</p>

<figref num="1">This is an example of a block diagram depicting a network architecture of a network that can be applied according to the teachings of the present invention.</figref><figref num="2">This is an example of a block diagram illustrating a candidate path related to the telecommunications system of FIG.</figref><figref num="3">This is an example of a block diagram illustrating the candidate paths in FIG. 2 for the internal elements of an exemplary media gateway pair.</figref><figref num="4">It is an example of a block diagram illustrating an exemplary media gateway exchanging codec list messages containing TAI elements, highly compressed routing instructions, and TAI thresholds.</figref><figref num="5">It is an example of the block diagram explaining the exemplary information element of FIG.</figref><figref num="6">It is a flowchart which depicts the codec selection procedure according to the teaching of this invention.</figref><figref num="7">This is an example of a flowchart diagram depicting one aspect of the codec selection procedure according to the teaching of the present invention.</figref>

Hereinafter, the present invention will be described in more detail with reference to embodiments and drawings. The same quotation marks indicate the same component.

In the following specification, specific details are given to provide a complete understanding of the invention, for illustration purposes, not limitation. It will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that deviate from these specific details. In particular, the features described herein are application specific integrated circuits (ASICs), using software that works with programmed microprocessors or general purpose computers, using separate hardware circuits. ) And / or may be implemented using one or more digital signal processors (DSPs).

Here, an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 7. First, a communication system 100 in which the present invention is implemented will be described with reference to FIG. Communication system 100 may be a combination of wireless / wired systems. Communication system 100 includes a set of nodes 102-112 through which signals related to communication connections such as individual voice telephone conversations conducted between mobile telephones are sent. An individual node represents a system consisting of individual parts of a telecommunications device, such as a server, computer processor, and the like, or such elements. In the example of FIG. 1, the nodes include a set of MSC servers, namely control node 102, control node 104, control node 106, control signals are sent through these control nodes, and a set of MGW (Media). Gateway, media gateway), that is, the payload node 108, the payload node 110, the payload node 112, through which the actual payload data corresponding to the connection 113, such as a voice connection, is sent. In addition, the node includes a VLR (Visitor Location Register) 103 associated with the MSC server 102 and a VLR (Area Location Register) 107 associated with the MSC server 106. The VLR103 can be connected to the HLR (Home Location Register) 105, and the VLR107 can be connected to the HLR (Home Location Register) 109.

An exemplary connection comprises four parts 301, 302, 303, and 304. Nodes are shown to be placed within a stage. In particular, the outgoing section 115, the intermediate section 117, and the incoming section 119 are described. Node 102, node 103, node 105, and node 108 of the outgoing section 115 are associated with a user device (not clearly shown) that is the starting point of the connection. The HLR105 is an HLR of a subscriber's home network (referred to herein as an outgoing subscriber) using a user device that is the starting point of a connection. In such a situation, the VLR103 stores the subscription information associated with the outgoing subscriber, which is pre-downloaded from the HLR105, for example, by the insert subscriber data MAP operation. According to the present invention, the subscription information for the outgoing subscriber includes a subscription quality level indicating a target quality level for the outgoing subscriber.

In the example shown, each interval contains one control node and one payload node. However, it will be appreciated that part of the hierarchy may contain multiple control nodes or payload nodes, and some control nodes may control payload nodes in multiple sections. Therefore, the range of each section is somewhat unclear. The term interval is used herein primarily to distinguish between the outgoing part, the intermediate part (if any), and the incoming part of a connection for simplicity. (Note that in the figure, the O-MSC can also act as a TSC node and a GMSC node, while the I-MSC can only be a TSC node and the T-MSC can also be a TSC.)

Depending on the outgoing user device, the signals exchanged between the outgoing node and the user device are, for example, from the UTRAN system via Iu, from the GERAN system via A, from the PSTN system via TDM, and from the NGN system. May be received via IP or from the IMS system via IP. UTRAN stands for UTMS Terrestrial Radio Access Network. Iu is an abbreviation for UTRAN interface. GERAN stands for GSM / EDGE Radio Access Network, and EDGE stands for enhanced data rates for GSM evolution. A refers to the interface in the GERAN architecture between MSC / MGW and GERAN's base station subsystem (BSS). PSTN is the public switched telephone network and TDM refers to time division multiplexing. IMS is the IP Multimedia Subsystem and NGN refers to the next generation network.

Incoming nodes (106, 107, 109, 112) are associated with the incoming user device receiving the connection. The HLR109 is the HLR of the home network of a subscriber (referred to herein as an incoming subscriber) who uses a user device to terminate the connection. In such a situation, the VLR107 stores the subscription information associated with the incoming subscriber, which is pre-downloaded from the HLR109, for example by the insert subscriber data MAP operation. According to the present invention, the subscription information for an incoming subscriber includes a subscription quality level indicating a target quality level for the incoming subscriber. If both the outgoing and incoming subscribers belong to the same home network, the HLR105 and HLR109 will probably be the same, and the distinction between the HLR105 and HLR109 is simply logical. Similarly, depending on the incoming user device, the signal exchanged between the incoming node and the incoming device is via Iu from the UTRAN system, via A from the GERAN system, via TDM from the PSTN system, or via TDM. It may be received from the NGN system via IMS. Intermediate nodes (104, 110) represent any additional nodes that may be needed between the outgoing and incoming nodes.

Various messages are transmitted between the MSC servers to establish a connection, process it, and finally terminate it. Illustrative messages include establishment messages, change messages, and acknowledgment messages related to change messages or confirmation of establishment messages. An exemplary message 123 is shown in FIG. 1 and is relayed from the MSC server 104 to the MSC server 106. One or more transcoders (114, 116, 118) are provided within various MGWs to relay voice for telephone conversations. Although Figure 1 depicts only one transcoder per MGW, in practice each MGW may support a large number of transcodes. Moreover, although not shown, the outgoing or incoming user device may also include one or more codecs.

The transcoder may optionally use one or more codecs to allow transmission within a limited bit rate that may be associated with a particular connection, such as the exemplary connection 113. Compress and decompress audio. The audio is compressed by the transcoder in one section and then decompressed by the transcoder in another section. These are done according to the specific codecs available to both transcoders. Therefore, the codec itself essentially represents a connection between transcoders. (This is explained more clearly in Figure 2 and discussed below.) Illustrative codecs include GSM_HR, GSM_EFR, and AMR. Each time a codec is used, the act of coding and subsequent decoding of the voice tends to degrade or impair the voice quality. Different codecs can degrade or degrade voice quality in different amounts.

The information contained in the control message, for example message 123, includes information related to the codecs available within the individual nodes along the connection path. In particular, preferably, the message is a list of "supported codecs", i.e. a coded / that can be executed between various MGW transcoders and may be started or stopped during any particular connection. Contains a list of decryption methods. Using the information contained in the list of supported codecs, the MSC server selects and uses the codec along the connection 113. In addition to providing a list of supported codecs, message 123 preferably also contains an information element that has one degradation value per supported codec, with each degraded value associated with the supported codec. The predicted cumulative deterioration along the candidate connection path 121 is shown. Further, as described in more detail below, message 123 preferably includes an information element indicating the subscription target quality level of the outgoing subscriber. Moreover, message 123 should preferably have the required bandwidth minimized for at least one connection segment of the connection, and the bandwidth minimization requirement takes precedence over the subscription target quality level requirement. Includes a display indicating that.

The information elements of message 123 will be described in great detail below. However, first, the candidate connection path will be described with reference to FIGS. 2 and 3. FIG. 2 illustrates an exemplary codec that may be used between MGWs in the three sections of FIG. Each MGW has a transcoder (Fig. 3) that can implement various codecs, and the codecs are different from each other and may be different from the codecs of other sections. In the example of FIG. 2, both the outgoing user device (not shown) and the outgoing section can support codecs 11 to 15, so the connection portion 301 is implemented using one of codecs 11 to 15. Will be done. Both the outgoing and intermediate sections can support Codec 1 through Codec 5, so the connection portion 302 is also implemented using one of Codec 1 through Codec 5. Both the intermediate section and the incoming section can support codecs 6 to 10, so the connection portion 303 is implemented using one of codecs 6 to 10.

Many possible connection paths may be defined through the codec from the outgoing section to the incoming section. These are indicated by dashed lines (phantom lines). With multiple intermediate intervals, there can be quite a few possible paths. Preferably, the outgoing user device and the incoming user device also support a plurality of codecs, and therefore the connection path from the outgoing user device to the incoming user device may have a larger number of possible connection paths. Ideally, all MGWs support the same list of alternative codecs, allowing the MSC to choose one codec end-to-end, depending on the calling and / or incoming device.

For any given codec supported by a transcoder in a particular interval, one of the possible paths to that interval is, for example, based on the predicted cumulative connection degradation along the path to that interval. , Suitable or considered optimal. In such situations, this suitable or optimal path is referred to as a "candidate path". This is because it represents one feasible candidate for the final connection path throughout the sequence (ie, connection 113 in FIG. 1). Therefore, in such a situation, not all possible paths are considered "candidate paths". Rather, for each supported codec in each interval, only one candidate path is selected from all possible paths leading to that interval. In each section, the deterioration value for each supported codec in the section is held in message 123 of FIG. The deterioration value represents at least the total deterioration along the candidate path leading to the section. A particular candidate path is defined by a combination of codecs applied within the various MGWs.

One exemplary candidate path is highlighted in Figure 2. More specifically, path 121 represents a "candidate path" for codec 125 supported by incoming segment 119. A degradation value indicating degradation along path 121 is stored in message 123. Although not highlighted in the figure, each of the other supported codecs in the incoming segment also has only one candidate path associated with it. Therefore, in this simplified example, there are five candidate paths, as the incoming section supports five different codecs. Each degradation value is also kept in message 123 for those candidate paths. Finally, one of these candidate paths leading to the incoming section is selected as the final connection path. According to the teachings of the present invention, the final path is chosen so that the overall degradation calculated for the path based on various degradation values is within the permissible degradation values. Advantageously, the range of permissible degradation values is associated with the subscription contract of either the outgoing or incoming subscriber. Instead, if an indication is detected that the bandwidth required for the connection should be minimized and that minimizing the required bandwidth takes precedence over the subscription target quality level. Advantageously, the permissible degradation value still has, as an upper limit, a threshold indicating the maximum permissible degradation for the connection. In practice, the permissible degradation value threshold will not be stricter than the maximum value in the subscription degradation value range. However, the permissible deterioration threshold can also be determined according to the subscription contract. Alternatively, the degradation threshold could also be defined by the operator operating the network 100.

Once the final path is selected, various codecs along that particular path are subsequently used to process the audio signal.

Figure 3 illustrates how payload data is sent through the MGW. Each MGW contains one or more transcoders. In FIG. 3, the transcoder 114 of the outgoing MGW 108 is shown and the transcoder 116 of the intermediate MGW 110 is shown. The transcoder 114 can implement codec 11 through codec 15 and codec 1 through codec 5, so codec 11 through codec 15 and codec 1 through codec 5 are illustrated in the figure. However, it will be appreciated that the codec does not represent an element of the device within the transcoder, but a coding scheme supported by the transcoder. The transcoder 116 can support codec 1 through codec 5 and codec 6 through codec 10. As shown in the figure, transmission between MGWs occurs between similar codec parts of the transcoder. That is, the transcoder 114 encodes the voice via the codec 5, and then the transcoder 116 decodes the voice using the codec 5. Internal transmission of the payload within the MGW is described via line 305 and may be implemented, for example, via linear PCM. For example, audio decoded by the codec 11 decoder of the transcoder 114 could be internally transmitted to the codec 5 encoder of the transcoder 114 via PCM for subsequent transmission to the MGW 110. However, the routing of internal signals does not have to be between similar codecs. CoordinationOne of the key aspects of the selection procedure is that each MSC node in the path has only a limited "local" perspective on its resources and an incoming list of candidate codecs (paths), but the whole procedure. The point is that you will always find the best one for a particular codec. Each node in the path preselects at some point in order to minimize the flow of information to the immediately following node, without compromising optimality and without knowing the resources of subsequent sections.

The general concept is that the intermediate node receives a list of n supported codecs from the previous node, along with n associated cumulative degradations for each candidate. The intermediate node knows all of its m codecs and the m associated degradations it would cause if these codecs were selected and inserted into the path. Therefore, the intermediate node can calculate all of the n × m combinations and all of these n × m cumulative degradations. Then, in order to keep the sending list manageable, the intermediate node must select k from these candidates and send them to the immediately following node with k associated cumulative degradation. In the example of Figure 3, k is equal to n, but in general, the list of candidates may be larger here than in the incoming list.

As an example of defining candidate paths by codec combination in MGW, the highlighted candidate paths are the combination of codec 11 and codec 5 in the outgoing MGW, the combination of codec 5 and codec 10 in the intermediate MGW, and Not shown, but defined by a further combination in the incoming MGW. The specific MGW codec combination for the candidate path is determined at call setup in the corresponding control MSC server and stored in the control MSC server. For example, the outgoing MSC server 102 remembers that the highlighted candidate path comprises a combination of codec 11 and codec 5 in the controlled outgoing MGW 108.

Then, referring to FIGS. 4 and 5, the information element 120 is included in message 123 and is relayed between the MSC server 102 and the MSC server 104. Here, the information element 120 is a list of support codecs 122, a subscription quality level index 127 indicating a target quality level for outgoing subscribers, and individual candidate paths leading to the support codec 122. · Total accumulated degradation (TAI, total accumulated) listing degradation values 126 associated with individual candidate paths including codec 122 impairment) Also includes data element 124. Further, the information element 120 includes a TAI threshold 128 indicating the maximum permissible degradation and a highly compressed path indication 129 indicating whether the required bandwidth should be minimized for at least one connection section of the connection. The TAI threshold 128 may be specified by the operator of the communication network 100 or may be determined according to the subscription contract. For (TAI) data element 124 for each particular support codec (or other factor that may affect connection quality) for a given interval, the individual TAI values are for that particular codec for that particular interval. It is stored in the TAI element that represents the total predicted deterioration associated with the candidate path including the specific codec. Therefore, the TAI element contains cumulative degradation for each of the listed supported codecs. That is, the TAI element is associated with a list of supported encodings, not a list of specific transcoder devices. For the example in Figure 2, message 123 sent from the outgoing interval to the intermediate interval results in a list of the five codecs supported by the outgoing interval, as well as an index for each of the five codecs supported by the outgoing interval. Also includes values. Each index value is a candidate path leading to a supported codec of interest and represents a predicted cumulative deterioration along the candidate path including the codec of interest. After the message is received by the intermediate interval, the intermediate interval will then change the indicator value to reflect the codecs supported by the intermediate interval. Preferably, the indicator 124 is sent only between the control nodes (102 to 106), while the connection 113 itself is established between the payload nodes (108 to 112). Advantageously, the subscription target quality level 127 corresponds to the permissible TAI range. In this way, the coordinates in the list of supported codecs associated with the corresponding TAI values that are outside the allowable TAI values corresponding to the subscription quality level. You can preselect a list of supported codecs by removing the mark. Moreover, according to one particular embodiment of the invention, the control node (102 to 106) advantageously requires one or more codecs having the relevant TAI value within the permissible TAI value range. Add to the list of supported codecs accordingly.

Returning to the example in Figure 1, first, the outgoing subscriber's subscription target quality level 127 is determined by the outgoing MSC102. To that end, the MSC102 may access the outgoing subscriber's subscriber data record stored in the VLR103 and previously downloaded from the outgoing subscriber's HLR105. Moreover, the MSC102 may access the outgoing subscriber's subscriber data record to determine the TAI threshold that indicates the maximum allowed connection degradation for the outgoing subscriber. Alternatively, the MSC102 may perform an IMSI number sequence analysis to map the outgoing subscriber's IMSI to the subscription target quality level. Further, first, the MSC102 of the outgoing section 115 generates a TAI element of message 123 based on all the codecs supported by the outgoing section 115 and all the knowledge that the outgoing section 115 has about the path 301 from the outgoing terminal to the MGW 108. To. The subscription target quality level 127 and preferably the TAI threshold 128 are then sent along with the TAI element to the MSC 104 in the intermediate section. The MSC104 in the intermediate section then stores the received TAI value and updates the TAI value based on the codec supported by the MGW110 in the intermediate section. The individual degradation values may remain unchanged or may be increased due to additional predicted degradation. The outgoing MSC102 requires that the connection section 302 between the outgoing MGW 108 and the intermediate MGW 110 be a high compression path, i.e., to minimize transmission bandwidth rather than the requirement that the configured connection meet the subscription target quality level. Check if is shown as part of the preferred connection. The operator of the communication network 100 configures a particular part of the connection within its communication network 100 to be a "highly compressed path" so that the bandwidth resource utilization for that particular part of the connection is used. Can be improved. This is especially advantageous when bandwidth resources are scarce, for example when some of the connections have satellite links. The result of the examination is a positive response

The outgoing subscriber's subscription quality level indicator 127, the TAI element 124, and preferably the TAI threshold rating and the high compression route indication 129 are then sent to the MSC106 of the incoming section 119, and the incoming section is further received. Update the TAI value based on all the codecs supported by the MGW112 of the section and all the knowledge that the incoming section may have about the path 304 from the MGW112 to the called terminal. In addition to the subscription quality level of the outgoing subscriber, the MSC106 advantageously determines the subscription quality level of the subscriber using the incoming user device, as referred to herein. Therefore, a method similar to the method used in relation to the subscription quality level of the outgoing subscriber described above may be used. That is, the MSC106 may access the subscriber data record stored in the VLR107, which is previously downloaded from the incoming subscriber's HLR109. Alternatively, the MSC106 may perform an IMSI number sequence analysis to map the incoming subscriber's IMSI to the subscription target quality level. Based on the information in the TAI element and at least one of the outgoing subscriber's subscription target quality level and the incoming subscriber's subscription target quality level, the incoming MSC106 has a degradation to the overall connection of the outgoing subscriber or Select a combination of codecs for use in section 303 and section 304 of the path so that it is within the degradation value range corresponding to the incoming subscriber's subscription quality level. In that regard, the operator may provide a service definition that specifies whether to consider the subscription quality level of the outgoing or incoming subscriber to select the codec combination. However, as an alternative, the choice of codec may depend on both the outgoing subscriber's subscription quality level and the incoming subscriber's subscription quality level, as illustrated by the exemplary embodiments described below. .. In the context of the exemplary embodiments described below, the subscription quality levels'low','normal', and'high' are theories.

According to the first embodiment, the outgoing MSC102 then creates a list of supported codecs without considering the outgoing subscriber's subscription quality level. Even if the outgoing subscriber's subscription connection quality level is'low quality', the codec associated with the total cumulative degradation corresponding to the'normal'or'high' connection quality associated with the calling subscriber , Included in the list of supported codecs. An indicator of the outgoing subscriber's subscription target quality level is included in message '123' as described above. The incoming MSC106 examines the received subscription quality level indicator to determine the relevant range of permissible degradation values for the connection. The MSC106 then selects the codec so that the predicted degradation value for the connection is within the determined range of the permissible degradation value. In this embodiment, the incoming MSC106 has the freedom to choose the codec to be adopted and is not limited by the preselection reflected in the list of supported codecs. In this way, the lack of selectable support codecs may avoid the situation where the call connection must retreat to PCM.

According to a further embodiment, the outgoing MSC102 examines the outgoing subscriber's subscription quality level prior to creating a list of supported codecs. In doing so, the outgoing MSC102 considers only the codecs associated with the predicted connection quality that have a degradation value within the permissible degradation value associated with the outgoing subscriber's subscription quality level. That is, for subscribers with'low'connection quality subscriptions, a limited list of supported codecs is created according to the low quality. When the incoming MSC106 selects the codec to be used, the selection is limited to the codecs in the list of preselected supported codecs. This allows the connection quality level even if the subscription quality level indicator is not transmitted in message 123 or the incoming MSC106 is not configured to recognize the subscription quality level indicator received in message 123. Can be controlled. According to another embodiment, both the outgoing subscriber's subscription target quality level and the incoming subscriber's subscription target quality level are considered in the codec selection process. To that end, the outgoing MSC102 considers the outgoing subscriber's subscription quality level to produce a list of support codecs with predictive degradation that is equal to or better than the range corresponding to the outgoing subscriber's subscription. In the subsequent selection of codecs used, the incoming MSC106 creates a similar internal list of codecs with predictive degradation equal to or better than the range corresponding to the incoming subscriber's subscription. The incoming MSC106 then compiles the list of supported codecs and the internal list into a merged list of codecs provided in both the list of supported codecs and the internal list, and connects within the merged list. Select the codec used for.

In a similar manner, the outgoing MSC102 could create a list of supported codecs with predictive degradation equal to or inferior to the range corresponding to the outgoing subscriber's subscription, and the incoming MSC106 would be able to create a list of incoming subscribers. It would be possible to create an internal list of codecs with predictive degradation that is equal to or inferior to the range corresponding to the subscription agreement.

Still further embodiments provide different connection quality levels for outgoing and incoming subscribers. The incoming MSC106 then examines the outgoing subscriber's subscription quality level received in message 123 and selects the codec for transmission towards the outgoing subscriber accordingly. The incoming MSC106 also examines the incoming subscriber's subscription quality level to select a codec for transmission towards the incoming subscriber, as described above. Advantageously, the outgoing user device and the incoming user device use different configurations of the same multi-rate voice codec type. Different voice quality levels for transmission from the outgoing user device to the incoming user device and for transmission from the incoming user device to the outgoing user device can be achieved by rate control. From control node 102 to control node 106, MGW 114 to MGW 118 are then operated so that different rate control commands are used in different transmission directions.

According to yet another embodiment, different subscriber classes are defined. The subscriber class determines which of the above methods will be applied to select the codec if the outgoing and incoming subscribers are subscribed to different target quality levels. Prescribe. The indication of the subscriber class for a particular subscriber is then also included in the subscriber data record.

Note that the MSC106 must select the codec for path 303 from the list of codecs in the Supported Codec List received from the MSC104. The MSC106 must select the codec for path 304 from the list received from the receiving terminal. Ideally, these codecs for path 303 and path 304 are identical and do not require transcoding. The MSC106 then relays the selected codec and the alternative codec list and associated TAI elements backwards through various sections of MSC104, MSC102. As a result, these MSCs can examine the previously stored codec combinations of the candidate path, and then select and activate the codecs for use in sections 302 and 301 of the path. Thus, according to this embodiment, the codec selected for the final connection section determines the selected candidate connection path, which determines the selection of the codec in the intermediate connection section.

However, as an alternative, end-to-end degradation calculations can also be performed on the intermediate or outgoing connection section to determine which codec is selected for the intermediate or outgoing connection section. Figure 4 shows the outgoing MSC server 102, the intermediate MSC104, and the incoming MSC106. The message 123 including the information element 120 is transmitted from the outgoing MSC server 102 to the intermediate MSC server 104 in the forward direction of the call when the call is set. Information element 120 receives and stores selectable support codecs and associated TAI values on the intermediate MSC104. After that, when the call is set, the message 133 having the information element 130 having the same format as the information element 120 described above is transmitted from the incoming MSC server 106 to the intermediate MSC server 104 in the reverse direction of the call. Information element 130 is a list of codecs available in the subsequent connection section, including the codecs selected for the subsequent connection section, as well as the TAI value associated with the codec selected for the subsequent connection section. It also has a TAI value associated with the available codecs, including. After that, the intermediate MSC server 104 considers the TAI values that have been received and stored so far for the codec candidates that can be selected in the specific connection section controlled by the MSC server 104, and makes a specific. To calculate the end-to-end TAI values that may result from selecting codec candidates for the connection interval, these TAI values and the received TAI of the codec selected for the subsequent connection interval. Combine with the value. Subsequent codec candidates may be selected that are within the permissible range of TAI values or have a calculated end-to-end TAI value that meets at least the maximum permissible TAI threshold. According to a preferred embodiment, a highly compressed path indication is provided within the TAI element 130 indicating whether at least one of the connection sections needs to minimize the transmission bandwidth devoted to the connection. TAI element 130 is examined and uses a highly compressed path When instructed to do so, it is determined that the requirement to minimize transmission bandwidth takes precedence over the requirement that the configured connections comply with the subscription target quality level. After that, a less stringent maximum permissible TAI threshold is applied in some cases. The codec selected in a particular connection interval is then combined with the calculated associated TAI value to allow similar TAI value calculation and codec selection in the next transmission interval in the opposite direction. It may be sent in the opposite direction.

The information contained within the data element 124 is not limited to providing an indication of cumulative degradation due to the operation of the codec sequence along the candidate path, as well as degradation due to radio degradation associated with the candidate path. Alternatively, acoustic degradation, or degradation due to digital signal processing, such as noise reduction, echo cancellation, level compensation, and the like, can be additionally (or selectively) reflected. For signal quality improvement processing techniques such as noise reduction, echo cancellation, and level compensation, cumulative degradation may also be reduced.

Preferably, the new TAI element 124, subscription quality level display 127, TAI threshold 128, and high compression path indication 129 are simply present in the (existing) list of message support codecs, as if they were in the list. Inserted as if it were just another supported codec. Therefore, any MSC that does not recognize the TAI element or another newly introduced display and is not configured to use it effectively makes the TAI element or other display just as if it were an unsupported codec. As if, it would simply be deleted. The MSC, which is configured to recognize and effectively use the TAI element, subscription quality level display 127, TAI threshold 128, or high compression path indication 129, updates the TAI element and determines the codec sequence to be used. That is, data will be extracted from the elements from that part of the connection controlled by a particular MSC to use at least to determine which codec should be started or stopped. Thus, the TAI element, subscription quality level display, TAI threshold, and high compression path indication are backward compatible. That is, it is compatible with any of the existing network components that are not specifically configured to recognize and effectively use TAI elements, subscription quality level indications, TAI thresholds, or high compression path indications. Note that MSCs configured to recognize and make good use of TAI elements can choose codecs either by "external" or "internal" selection. By external selection, the MSC simply means selecting a codec from the list of supported codecs for the incoming link. In the internal selection, the MSC selects additional, potentially different codecs based on its ability to generate a new TAI list with updated TAI values, after which the new TAI list originates. Transferred to another MSC via link.

Figure 6 summarizes the use of TAI elements with a specific focus on incoming MSCs. Briefly, starting with step 200, for a given individual connection, for example a particular cell phone call, the incoming MSC preferably incorporates the subscription quality level of the subscriber who made the call. -Receive a list of codecs. The list of supported codecs also incorporates a TAI element that lists the individual degradation values for the candidate path, represented by these codec candidates. Then, in the first step, any unsupported codecs are removed from the list (latest, not shown). That is, any codecs associated with codecs that are not supported by certain parts of the incoming MSC-controlled connection are removed from the list. This follows other traditional techniques. These TAI values are also removed along with unsupported codec candidates. At step 204, the individual degradation values are updated to reflect the additional degradation due to the codecs in the incoming segment (incoming MGW) and the incoming path to the terminal, after which the list of remaining supported codecs is listed. Analyzed to determine the codec sequence from within. Note that the incoming MSC has the authority to select a codec for the incoming link and can provide one or more codecs for the outgoing link. At step 205, the incoming MSC is associated with either the subscription quality level associated with the outgoing subscriber and previously received with a list of supported codecs, or the subscription quality level associated with the incoming subscriber. Find out. The subscription quality level of the incoming subscriber may be determined by IMSI number analysis, as described above, or may be retrieved from the subscriber record of the incoming subscriber. The incoming MSC then determines the range of associated degradation values, i.e. the range of permissible degradation values corresponding to the subscription quality level examined.

Subsequently, in step 206, the incoming MSC selects a codec for the incoming and outgoing connection sections so that the overall cumulative degradation for the connection is within the determined permissible degradation value.

At step 207, the incoming MSC activates or deactivates these two codecs from the communication link according to the optimal codec sequence determined for that particular connection. At this time, the incoming MSC controls the MGW and sends a control signal to one or more related MGWs so that the incoming MSC routes the connection through a codec determined to be optimal for that particular part of the connection. send.

In step 208, the MSCs in the incoming section relay the TAI element and the codecs selected for the incoming connection section of the incoming MSCs to the MSCs in the preceding section, and these MSCs correspond to the selected codecs. Allows you to trace back the candidate connection paths and also allow you to select your own codec for these MSCs, and launch or launch the selected codec according to the selected candidate connection path to the MGW associated with these MSCs. It is also possible to instruct to stop.

Finally, in step 210, the outgoing MSC initiates the connection. Data for the connection, such as encoded audio data, is sent through the selected codec sequence. Note that the example in Figure 1 is a simplified example that focuses on the incoming section and provides a focused overview of the MSC's behavior. In fact, the MSCs in each section access each TAI element and, in some cases, change each TAI element.

Preferably, the TAI indicators of the present invention are also technologies in 3GPP that aim to avoid voice quality degradation caused by unnecessary transcoding along the voice path (see 3GPP TS 28.062) and TrFO (see 3GPP TS 28.062). Implemented in connection with 3GPP TS 23.153). Both techniques allow a list of candidate codec types to be exchanged to make a decision as to which codec type to use for which sublink of the voice path. Further information may be found in 3GPP TR 23.977 (BARS). Codec negotiation is by in-band signaling (for TFO, see TS 28.062), or by OoBTC (see 3GPP TS 23.153), or SDP (see SIP, Internet Engineering Task Force). By SIP (see IETF Standards again) with (Committee) IETF Standards), and by IMS (IP This can be achieved by a 3GPP improved version of SIP called the multimedia subsystem "). However, the principles of the present invention may be used in connection with other technologies as well. For simplicity, TAI Examples of elements are primarily provided herein for use with OoBTC.

The value inserted into the TAI may be first derived using the ITU-T E model. In particular, the E model (see G.107 and G.128) and other sources (see 3GPP TR 26.975) have an intrinsic TAI value (a degradation factor also called the IE value in the E model). Allows you to specify or derive. "Intrinsic" means "without any transmission error". The "degradation factor" (Ie) defined in the standard E model may also be modified to give some "drift" to the overall decision, in some cases. During call setup, the outgoing call control node (eg, the MSC server in BICN for mobile phone outgoing calls) generates a list of codec types provided as an alternative to this call (ie, the supported codec list). See TS 23.153 for this. This is otherwise the same as before. Moreover, however, a new TAI IE (IE is an information element) is added to the supported codec list as a "dummy codec type" entry. This TAI IE holds one new integer parameter (referred to herein as tai1, tai2, ...) For each entry of codec type IE in the supported codec list. Further, according to the teachings of the present invention, the "subscription quality level" is included in the "dummy codec type" entry as a new parameter in the supported codec list. In one example, this new parameter has a value of 0 (no subscription), 1 (high quality subscription), 2 (normal quality subscription), and 3 (low quality subscription). Have one.

Here, FIG. 7 showing a flowchart of the codec selection procedure 400 according to the teaching of the present invention will be described. The codec selection procedure 400 depicted can be used by a control node such as the intermediate MSC server 104 with information such as information received by information element 130 and information element 120. More precisely, the codec selection procedure depicted is a list of selected codecs in subsequent connections, a list of codecs available in the current connection, and codecs in the codec list available in subsequent connections. Dedicated to choosing the codec for the current connection, based on the list of corresponding TAI values for subsequent connections associated with using and the TAI threshold, which indicates the maximum permissible degradation of the established connection. ing. Advantageously, the selected codec, the TAI value associated with the available codec, and the TAI threshold are all received by the information element 130 in a format similar to the format of the information element 120 depicted in FIG. Will be done.

In addition, codec selection step 400 is based on a list of supported codecs supported for the previous connection and the associated TAI value for the preceding connection, and the TAI value is supported for the current connection. -List of codecs Represents the cumulative degradation of the entire candidate connection path associated with using a codec. Advantageously, both the list of supported codecs and the associated TAI values are received with the information element 120 and stored in the control node in response to the receive step. The control node has access to highly compressed routing instructions. The high compression path indication is advantageously received with the information element 130 and whether the configured connection has any connection interval that requires the use of optimized bandwidth, i.e. bandwidth. Indicates that the use of is to be prioritized over subscription connection quality. This collation is done in step 402. If the answer is no and there is no highly compressed route indication, then process step 404 is performed to select the codec of the candidate path that is pre-stored as associated with the selected codec of the subsequent connection interval. Will be done. If the result of the collation in step 402 is yes, we aim to select a codec that provides higher compression than the codec associated with and stored in the selected codec. To that end, step 406 checks for any of the codecs available at the current connection that provide higher compression. If the result of the collation is yes and there is a codec with a higher compression than now, then the codec with the next higher compression is preselected and the preselected codec is applied in step 408. Is asked if there is a possibility of exceeding the TAI threshold. To this end, it is based on a combination of the TAI value received for the selected codec of the subsequent connection interval and the TAI value received for the preselected codec. The predicted degradation from end to end is calculated. The calculated end-to-end degradation is then compared to the TAI threshold to determine if using a preselected codec could exceed the TAI threshold. If the result is no, the procedure continues to apply step 406 again to preselect the codec with the next highest compression. This procedure continues until the preselected codec exceeds the TAI threshold. Then, in step 410, the previous codec, the last codec that meets the TAI threshold, is selected as the codec applied to the current connection. This is the codec with the highest compression that still meets the TAI threshold.

If the result of collation step 406 is negative and no codec that provides higher compression than previously stored codecs can be found in the list of available codecs, the procedure continues with collation step 412, followed by Checks if the codec selected for the connection part of is available in the received supported codec list. If the answer is yes, the codec selected in the subsequent connection section is also selected for the current connection section in step 414. If the result of collation step 412 is negative, processing step 416 is performed and the previously remembered codecs are associated with the selected codecs and each candidate path for subsequent connections. Be selected.