JP4797705B2 - Voice data relay method and system - Google Patents

Description

  The present invention relates to a voice data relay method and system for relaying voice data in a redundant configuration in which a plurality of gateway devices are provided between a subscriber telephone and a packet network.

  In general, a VoIP gateway device that relays voice data between a telephone set via a subscriber line and an IP network is usually configured in a single configuration because the subscriber phone itself is configured in a single configuration. However, recently, since further improvement in reliability is required, there is a case where the VoIP gateway device is configured to have a redundant configuration in addition to the main system as a duplex configuration.

When the VoIP gateway device has a duplex configuration, it is required to switch between the active system and the standby system without voice interruption. Therefore, the method disclosed in Patent Document 1 entitled “Redundant system switching method” is an RTP other than information on time stamp and sequence number from the active system to the standby system when switching between the active system and the standby system. / RTCP Session information and connectivity information are transferred. As a result, the VoIP device switched to the active system can start the decoding operation with the parameter value set in the RTP packet transmitted from the IP terminal as the initial value, and the active system and the standby system without interruption of voice. Can be switched.
JP-A-2005-57461

  However, in this method, the new operation system operates from the initial state regardless of the state of the old operation system. For this reason, it is inevitable that the call quality will be degraded until the state of the new operation system is restored to the same state as the old operation system. For example, until the IP packet that stayed in the old operational jitter buffer is discarded and the call is interrupted, or the optimization control in the new operational echo canceller is reset and the echo can be correctly removed In addition, a time of about 500 ms to 800 ms is required, and there is a problem that it makes the phone call feel uncomfortable during this time.

  An object of the present invention is to provide a voice data relay method and system capable of maintaining a call state before system switching and avoiding deterioration in call quality even when a multiplexing configuration is used.

The invention according to claim 1 is a voice data relay system including a plurality of gateway devices multiplexed between a subscriber telephone and a packet network, wherein one of the gateway devices is set as an active system. System switching setting means for setting the rest as a standby system, voice data transmission means for transmitting the voice data between the subscriber telephone and the packet network via a gateway device set in the active system, Duplicate data supply means for generating duplicate data including the same contents as the voice data and supplying the duplicate data to the gateway device set in the standby system, and the voice data transmission means is set in the operation system And transferring at least a part of the duplicated data received as the voice data while the selected gateway device is set as the standby system. That.

  According to the voice data relay method and system according to the present invention, even in the standby system, a configuration is provided in which voice data including the same contents as in the active system is supplied to the jitter buffer and the echo canceller, and the voice data is stored and the echo canceller. Is maintained in the standby system in the same state as the active system. As a result, it is possible to maintain the call state before the system switching and avoid the deterioration of the call quality.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment according to the present invention, and shows an overall configuration including a voice data relay system according to the present invention. The voice data relay system includes a 0-system gateway device 40 and a 1-system gateway device 50 as a multiplexing configuration between the subscriber telephone 10 and an IP (Internet Protocol) network 60 that is a packet network.

  The 0-system gateway device 40 and the 1-system gateway device 50 are gateway devices having the same configuration, and an IP that enables an IP telephone call using a normal subscriber telephone line network and VoIP (Voice over IP) technology. A function of relaying voice data to and from the network 60 is provided. In this embodiment, a duplex configuration using two gateway devices, that is, the 0-system gateway device 40 and the 1-system gateway device 50 is shown, but a redundant configuration using three or more gateway devices may be used.

  The system switching in the redundant configuration may be controlled from a controller (not shown) provided separately from the 0-system gateway device 40 and the 1-system gateway device 50, or the gateway devices 40 and 50 may perform autonomously. . The controller sets one of the 0-system gateway device 40 and the 1-system gateway device 50, for example, the 0-system gateway device 40 as an active gateway device and the other 1-system gateway device 50 as a standby gateway device. . As a result, the voice data is transmitted through the operation system route of the 0 system gateway device 40. When the 0-system gateway device 40 cannot be operated due to the occurrence of a failure, the controller performs system switching using the 1-system gateway device 50 that is the standby gateway device as the active gateway device, and sets the standby system route to the active system. Session information that has been set and interrupted is transferred from the 0-system gateway device 40 to the 1-system gateway device 50. As a result, the 1-system gateway device 50 takes over the previous session information and resumes transmission of the voice data. On the other hand, the 0-system gateway device 40 is set as a standby system gateway device after being restarted or corrected, and incorporated in the redundant configuration.

  The subscriber telephone 10 is a normal analog telephone or ISDN telephone, and is connected to a subscriber line interface (SLIC) 20. The subscriber line interface 20 is a circuit having a BORSCHT function. The subscriber line interface 20 inputs and outputs an analog voice signal to and from the subscriber telephone 10 via a normal two-wire interface, and the analog voice signal and digitized voice data. The audio data is input / output to / from the system switching selector 30.

  The system switching selector 30 is a circuit for selecting a system switching between the 0-system VoIP gateway device 40 and the 1-system VoIP gateway device 50, and sends voice data from the active VoIP gateway device to the subscriber line interface 20. In addition, the voice data from the subscriber line interface 20 is provided to both the 0-system VoIP gateway device 40 and the 1-system VoIP gateway device 50. The setting of which of the 0-system VoIP gateway device 40 and the 1-system VoIP gateway device 50 is the active gateway device or the standby gateway device is made by the controller (not shown). The controller also transfers session information of a call session that is being provided with service in the active gateway device to the standby gateway device during system switching. The system switching by the controller may be triggered by an instruction from an operator or automatically triggered by failure detection.

  Each of the 0-system gateway device 40 and the 1-system gateway device 50 is a gateway device having the same configuration. The 0-system gateway device 40 includes an echo canceller 41, an RTP encoder 42, an IP network interface 43, a data switching selector 44, an RTP decoder 45, and a jitter buffer 46. The first-system gateway device 50 includes an echo canceller 51, an RTP encoder 52, an IP network interface 53, a data switching selector 54, an RTP decoder 55, and a jitter buffer 56.

  Each of the echo cancellers 41 and 51 is an echo signal in which a voice signal including voice data transmitted from a transmitter on the IP network 60 side to the subscriber telephone 10 side returns from the subscriber telephone 10 side to the IP network 60 direction. Is a circuit for preventing the deterioration of the call quality on the side of the transmitter.

  Each of the RTP encoders 42 and 52 is a circuit that adds an RTP header to voice data and converts it into an IP packet. Each of the IP network interfaces 43 and 53 is a circuit that transmits and receives IP packets including voice data to and from the IP network 60, and transmits the IP packets from the RTP encoder 42 or 52 toward the IP network 60. An IP packet from the IP network 60 is supplied to both the data switching selectors 44 and 54.

  Each of the data switching selectors 44 and 54 selectively switches between the IP packet from the own IP network interface and the IP packet from the other IP network interface, and either of them is used as the own RTP decoder. It is a circuit to supply.

  For example, the data switching selector 44 selectively switches between an IP packet from the local IP network interface 43 and an IP packet from the other IP network interface 53, and either of them is switched to the local RTP decoder 45. To supply. The IP packet is selected by selecting an IP packet from the own IP network interface 43 when the 0-system gateway device 40 itself is set as the active gateway device, and the 0-system gateway device 40 itself becomes the standby gateway device. When set, an IP packet from the other-system IP network interface 53 is selected. With this configuration, the operational gateway device generates duplicate data including the same voice data as the IP packet to be transmitted, and supplies this to the standby gateway device.

  Each of the RTP decoders 45 and 55 is a circuit that extracts voice data by removing the RTP header from the IP packet supplied via the data switching selector 44 or 54, and supplies this to the jitter buffer 46 or 56. It has a function to analyze packet headers and analyze packet loss and fluctuations. Each of the jitter buffers 46 and 56 is a circuit that absorbs temporal fluctuations of the IP packet in the IP network 60 by accumulating and transferring the supplied voice data. By such fluctuation absorption, even when the reception interval of IP packets is disturbed and arrived, continuity of voice reproduction can be maintained and call quality on the receiver side can be maintained.

  FIG. 2 explains the flow of audio data in the redundant system configuration of this embodiment. Here, from the past, it is assumed that the 0-system VoIP gateway device 40 operates as an active gateway device and the 1-system VoIP gateway device 50 operates as a standby gateway device.

  The voice data carried on the IP packet from the IP network 60 reaches the system switch selector 30 through the 0-system VoIP gateway device 40 through the operation system path R1. At the same time, the audio data as the duplicated data reaches the system switching selector 30 through the 1-system VoIP gateway device 50 through the standby system path R2.

  Since the system switching selector 30 selects the 0-system VoIP gateway device 40 as the active VoIP gateway device, the voice data from the 0-system VoIP gateway device 40 is supplied to the subscriber telephone 10 via the subscriber line interface 20. Is done. On the other hand, the voice data from the 1-system VoIP gateway device 50 reaches the system switching selector 30, but is discarded here.

  Paths R3 and R4 are paths for echo signals returned from the 2-wire 4-wire hybrid circuit included in the subscriber line interface 20. The echo signal reaches each of the echo cancellers 41 and 51 through both paths R3 and R4. The operational echo canceller 41 searches for the optimization condition based on the audio data and the echo signal from the RTP decoder 45, and performs an appropriate echo cancellation operation based on this search. On the other hand, the standby echo canceller 51 is also supplied with audio data and echo signals. As a result, the standby echo canceller 51 holds the optimization condition for canceling the echo signal appropriate for the call session in which the active gateway device 40 is currently providing the service.

  Jitter buffers 46 and 56 are interposed in each of the active route R1 and the standby route R2. Each of the jitter buffers 46 and 56 stores and transfers audio data on the path. The jitter buffer 46 of the 0-system VoIP gateway device 40 performs an operation for absorbing packet fluctuations. On the other hand, the 1-system VoIP gateway device 50 retains the same voice data as the voice data staying in the jitter buffer 46 by accumulating and transferring the voice data that is duplicated data having the same contents.

  FIG. 3 explains how audio data is stored and transferred in the jitter buffer. It is assumed that audio data A, B, and C are retained in the jitter buffer 46 of the 0-system gateway device 40 that is an operational gateway device at a certain time. During this time, similarly, the voice data A, B, and C also stay in the jitter buffer 56 of the first gateway device 50 that is the standby gateway device.

  In such a situation, if a failure occurs in the 0-system gateway device 40, which is the operational gateway device, the processing relating to the voice data A, B, and C remains unprocessed, resulting in data loss. However, the 1-system gateway device 50 that has newly become an active-system gateway device can take over the call session by using the audio data A, B, and C that have stayed in its own jitter buffer 56. The voice data staying in the jitter buffer 46 and the jitter buffer 56 does not completely match the processing capacity of each gateway device and the time lag at the time of system switching. Can be minimized.

  FIG. 4 shows an operation procedure at the time of system switching in the present embodiment. Here, the 0-system gateway device 40 and the 1-system gateway device 50 are configured redundantly and are in operation in parallel. The 0-system gateway device 40 has been operating as an operational gateway device for a long time (step S1). On the other hand, the 1-system gateway device 50 operates as a standby system gateway device (step S2). Therefore, the 1-system gateway device 50 stores and transfers the audio data in the jitter buffer, as in the 0-system gateway device 40, and holds an optimization condition for echo cancellation in the echo canceller.

  Here, it is assumed that the system is switched at the timing of step S3. As a result, the 0-system gateway device 40 interrupts the call session provided at that time, and transfers the session information to the 1-system gateway device 50. The 1-system gateway device 50 takes over the session information, operates as an active gateway device, and resumes the operation that was interrupted by the system switching (step S4). At this time, the 1-system gateway device 50 transmits the duplicate data received while it is set to the standby system as it is as the audio data. That is, the 1-system gateway device 50 transmits the duplicate data staying in the jitter buffer as it is as voice data. Furthermore, using the optimization conditions for echo cancellation obtained based on such duplicated data, the echo cancellation operation is performed on the voice data newly received as the operating system.

  On the other hand, the 0-system gateway device 40 starts operation as a standby gateway device after an appropriate failure recovery operation (step S5) (step S6).

  As described above, in the embodiment of the present invention, when the system switching of the redundant configuration including the 0 system VoIP gateway device 40 and the 1 system gateway device 50 is performed, the voice data is discarded by using the duplicate data. This can reduce the probability of interruption and suppress the occurrence of call disconnection. In addition, the state of the echo cancellers 41 and 51 is not operated from the initial state, and the time required until the echo cancellers 41 and 51 can correctly remove the echo signal (for example, 500 ms to 800 ms) is omitted. Can suppress the occurrence of a sense of discomfort in the call.

  In the above embodiment, the gateway apparatus that accommodates the subscriber telephone has been described as an example. However, the present invention is applied not only to the VoIP gateway apparatus but also to an apparatus that accumulates voice data and includes an echo canceller. . For example, the present invention can be applied to a VoIP device such as a media gateway that does not directly accommodate a subscriber telephone. Further, the present invention has been described by taking the VoIP mode, that is, the communication mode for transferring a voice signal on the IP protocol as an example. However, the transfer protocol to be used is not limited to the IP protocol, but ATM (Asynchronous Transfer Mode) or FR (Frame Relay). It is also applicable to other packet protocols such as

1 is a block diagram showing an overall configuration including an audio data relay system according to an embodiment of the present invention. It is a block diagram explaining the flow of the audio | voice data in the redundant system structure of a present Example. It is a block diagram explaining the mode of the accumulation | storage transfer of the audio | voice data by the jitter buffer in a present Example. It is a sequence diagram which shows the operation | movement procedure at the time of the system switching in a present Example.

Explanation of symbols

10 Subscriber telephone 20 Subscriber line interface (SLIC)
30 system switching selector 40 0 system gateway device 50 1 system gateway device 60 IP network 41, 51 Echo canceller 42, 52 RTP encoder 43, 53 IP network interface 44, 54 Data switching selector 45, 55 RTP decoder 46, 56 Jitter buffer R1 , R2, R3 and R4 pathways

Claims (3)

A voice data relay system including a plurality of gateway devices multiplexed between a subscriber telephone and a packet network,
System switching setting means for setting one of the gateway devices as an active system and the rest as a standby system;
Voice data transmission means for transmitting the voice data between the subscriber telephone and the packet network via a gateway device set in the operational system;
Duplicate data supply means for generating duplicate data including the same content as the voice data and supplying the duplicate data to the gateway device set in the standby system,
The voice data transmission means transmits at least a part of duplicate data received as the voice data while the gateway device set as the operation system is set as the standby system. . 2. The voice data relay system according to claim 1, wherein the voice data transmission means transmits, as the voice data, replicated data staying in a jitter buffer built in a gateway device set in the operation system. . The voice data transmission means takes over the duplicate data as the voice data by taking over the optimization condition information for echo cancellation generated based on the duplicate data by an echo canceller built in the gateway device set in the operation system. 2. The voice data relay system according to claim 1, wherein the voice data relay system is transmitted as data.

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