JP4692412B2 - Voice packet signal receiver - Google Patents

Description

  The present invention relates to a voice packet signal receiving apparatus that receives a voice packet signal transmitted from a voice communication terminal such as a VoIP terminal, and more particularly, to a voice that absorbs fluctuation in a received voice packet signal, that is, performs fluctuation compensation. The present invention relates to a packet signal receiving apparatus.

  In packet communication via an IP network that is a packet transmission network, the time required for transmission varies for each packet according to a change in the congestion state of the transmission network, and the interval between continuously received packets varies, that is, “Fluctuation” occurs. When performing voice communication via the IP network using the VoIP technology, there is a problem that the continuity of the decoded voice is lost and the reproduced sound quality is deteriorated due to the influence of such “fluctuation”.

  Therefore, a method is known in which received packets are temporarily stored in a buffer memory called a fluctuation absorbing buffer, and the packets from this buffer are converted into audio signals at regular intervals, thereby absorbing such fluctuations and improving the reproduction sound quality. It has been. As the steady packet accumulation amount in the fluctuation absorbing buffer is increased, it becomes possible to cope with a large fluctuation that occurs instantaneously.

  On the other hand, packet accumulation in the buffer for absorbing fluctuation appears as a fixed delay for the audio signal. Therefore, it is necessary to recover this delay as appropriate. Patent Document 1 recognizes a silent part in a call and reduces the packet of the part, thereby recovering the call delay and efficiently realizing a natural voice call.

Further, the optimum value of the control parameter such as the packet accumulation amount differs depending on the network environment. Therefore, Patent Document 2 discloses a technique for monitoring a network state such as fluctuations in packet arrival intervals and autonomously changing control parameters such as a reception buffer length in accordance with the monitoring result of the network state ( (See FIG. 1).
Japanese Patent No. 3580723 Japanese Patent Application Laid-Open No. 2004-072242

  However, the optimum value of the control parameter varies greatly depending on the terminal type, such as whether the voice communication terminal that transmits the voice packet signal is a wired terminal or a wireless terminal, as well as the network environment. Therefore, depending on the method for selecting the optimum value of the control parameter only by the network environment, there is a problem that it is impossible to realize the optimum fluctuation absorption, that is, fluctuation compensation for each terminal.

  It is an object of the present invention to provide a voice packet signal receiving apparatus that enables optimum fluctuation compensation for individual voice communication terminals.

A voice packet signal receiving apparatus according to the present invention includes a receiving unit that receives voice packet signals arriving from a plurality of voice communication terminals via a packet transmission network, and a fluctuation compensating unit that performs fluctuation compensation on the received voice packet signals. The terminal type of the voice communication terminal is wired based on identification information of a communication standard between the voice communication terminal and the packet transmission network included in the received voice packet signal. Terminal type discriminating means for discriminating whether it is a terminal type or a radio terminal type, and control parameter supplying means for supplying the fluctuation compensator corresponding to the discriminated terminal type to the fluctuation compensator, the fluctuation compensation The unit is characterized by performing a fluctuation compensation operation according to the supplied control parameter.

  According to the voice packet signal receiving apparatus of the present invention, a configuration for identifying the terminal type of a voice communication terminal and performing fluctuation compensation corresponding to the terminal type is provided, and fluctuation compensation appropriate for each voice communication terminal can be performed. .

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

  FIG. 2 is an embodiment of the present invention, and shows the overall configuration including a voice packet signal receiving apparatus. The voice packet signal receiving device 40 is connected between the wireless terminal accommodating device 20 and the wired terminal accommodating device 21 and a private branch exchange (PBX) 50 via an IP network 30 which is a packet transmission network.

  The wireless terminal accommodating device 20 has a wireless access point function for accommodating the VoIP wireless terminal 10 by establishing a wireless link with the VoIP wireless terminal 10. The VoIP wireless terminal 10 is a voice communication terminal having a call function using VoIP technology, and has a function of transmitting and receiving voice packet signals to and from the voice packet signal receiving device 40 via the IP network 30 and the wireless terminal accommodating device 20. Is provided. The wireless terminal accommodating apparatus 20 also determines a communication standard to be used with the VoIP wireless terminal 10 by executing an arbitration procedure for establishing a wireless link. As the assumed communication standard, for example, a plurality of standards such as IEEE802.11a / b / g are assumed. Thereby, the wireless terminal accommodating apparatus 20 can determine the communication standard used by the VoIP wireless terminal 10. The determined communication standard is stored in the contents of the voice packet of the voice packet signal and notified to the voice packet signal receiving device 40.

  The wired terminal accommodating device 21 has a function of establishing a wired link with the VoIP wired terminal 11 and accommodating the VoIP wired terminal 11. The VoIP wired terminal 11 is a voice communication terminal having a call function using the VoIP technology, and has a function of transmitting and receiving voice packet signals to and from the voice packet signal receiving device 40 via the IP network 30 and the wired terminal accommodating device 21. Is provided. The wired terminal accommodating apparatus 21 also determines a communication standard used with the VoIP wired terminal 11 by executing an arbitration procedure for establishing a wired link. As an assumed communication standard, for example, 100BASE or 1000BASE defined in IEEE802.3 is assumed. Thereby, the wired terminal accommodating apparatus 21 can determine the communication standard used by the VoIP wired terminal 11. The determined communication standard is stored in the contents of the voice packet of the voice packet signal and notified to the voice packet signal receiving device 40.

  The voice packet signal receiving apparatus 40 includes a receiving unit 41, a receiving buffer 42, a non-packetizing unit 43, a voice decompression decoding unit 44, a terminal type identification unit 45, a control parameter table 46, and a reception buffer control unit 47. Including.

  The receiving unit 41 has a function of receiving a voice packet signal arriving via the IP network 30 and supplying each voice packet constituting the voice packet signal to the reception buffer 42. The reception buffer 42 has a function of accumulating the supplied voice packets, reading out the voice packets stored in a predetermined non-period in order, and transferring them to the non-packetizing unit 43. This accumulation and transfer function compensates for fluctuations. The reception buffer control unit 47 has a function of controlling the fluctuation compensation operation by the reception buffer 42 in accordance with the control parameter set in the control parameter table 46. As the control parameter, a control parameter corresponding to the terminal type notified from the terminal type identifying unit 45 is used. The control parameter table 46 is a table in which control parameters such as the buffer size of the reception buffer 42 are set in advance in association with each terminal type (see FIG. 3).

  The reception buffer 42 and the reception buffer control unit 47 constitute a fluctuation compensation unit that is a component of the present invention.

  The terminal type identifying unit 45 extracts information identifying the communication standard from the content of the voice packet supplied from the receiving unit 41, identifies the terminal type of the VoIP wireless terminal 10 or the VoIP wired terminal 11 according to this information, A function of notifying this to the reception buffer control unit 47 is provided. As a communication standard notification method, information identifying the communication standard may be embedded in the voice packet signal and the terminal type identifying unit 45 may capture the information to identify the terminal type.

  The non-packetizing unit 43 has a function of reading a voice packet from the reception buffer 42 at a predetermined period and performing a non-packetizing process for extracting a voice signal from the voice packet. The audio expansion / decoding unit 44 has a function of performing audio expansion / decoding processing on the audio signal obtained by the non-packetizing unit 43 and reproducing the audio signal. The voice decompression decoding process is performed by, for example, the voice coding standard G.264. It is assumed that a method based on a standard such as 293 is used. The audio signal expanded and decoded by the audio expansion / decoding unit 44 is sent to an external device such as the PBX 50, for example.

  FIG. 3 shows a setting example of the control parameter table shown in FIG. The control parameter table 46 includes at least settings of “communication standard” and “buffer size” corresponding to each of a plurality of “terminal types”. Furthermore, settings of “packet discard rate”, “delay recovery amount”, and “voice encoding method” may be included.

  The “buffer size” is the depth of the reception buffer measured by the time length, and this value gives the number of voice packet signals that can be stored. For example, if the packet length is 20 msec and the buffer size is 500 msec, a maximum of 25 received packets can be stored in the receive buffer. As a result, a maximum delay of 500 msec can occur in the voice packet signal.

  The “packet discard rate” represents the ratio between the total number of packets and the number of discarded packets. For example, if the discard rate is 0.1%, it means that 1 packet is discarded with 1000 packets, and if the packet discard rate is 0.2%, it means that 1 packet is discarded with 500 packets. The amount of delay recovery depends on the set value of the packet discard rate. For example, when the packet size is 20 ms and the packet discard rate is 0.1%, one packet is discarded from 1000 packets (20 sec period), and the delay recovery amount at that time is 20 ms.

  These control parameters can be determined by simulation or actual measurement. For example, wireless terminals are less stable than networks and are more likely to fluctuate than wired terminals, so higher values of buffer size and packet discard rate are expected to be appropriate.

  FIG. 4 shows a processing procedure executed in the configuration shown in FIG. Here, a mode in which the VoIP wireless terminal 10 transmits a voice packet signal to the voice packet signal receiving device 40 will be described.

  First, the VoIP wireless terminal 10 makes a connection request to the wireless terminal accommodating apparatus 20 (step S1). In response to the connection request, the wireless terminal accommodating apparatus 20 establishes a wireless link with the VoIP wireless terminal 10 (step S2). At this time, the wireless terminal accommodating apparatus 20 determines the communication standard of the communication means used with the VoIP wireless terminal 10 in the process of executing the arbitration procedure with the VoIP wireless terminal 10 (step S3). Next, the communication standard is notified to the voice packet signal receiving device 30 (step S4).

  In response to the notification of the communication standard, the voice packet signal receiving device 30 refers to the control parameter table using the communication standard as a key, and identifies the terminal type of the VoIP moneyless terminal 10 (step S5). Next, the voice packet signal receiving device 30 sets a reception buffer based on the control parameter corresponding to the identified terminal type (step S6). At least the buffer size is set as the control parameter setting. The buffer size setting determines how much fluctuation is absorbed through the voice packet signal.

  Thereafter, the VoIP wireless terminal 10 transmits the voice packet signal to the voice packet signal receiving device 30 (step S7). The wireless terminal accommodating apparatus 20 relays the transmitted voice packet signal (step S8). Next, the voice packet signal receiving device 30 receives the relayed voice packet signal, and performs fluctuation absorption according to the set control parameter, that is, fluctuation compensation processing (step S9).

  The voice packet signal receiving apparatus 30 can also perform delay compensation by packet discarding together with fluctuation compensation processing by the reception buffer. In this case, the reception buffer control unit 47 (see FIG. 2) discards random or specific packets out of the packets in the reception buffer at a rate according to the packet discard rate included in the control parameter. In this case, the reception buffer control unit 47 may selectively discard a specific packet whose voice packet content is silence.

  FIG. 5 shows the time change of the delay amount of the voice packet in the reception buffer. In the example of this graph, the packet discard rate is 0.1%, the packet size is 20 msec, and the buffer size is 500 msec.

  Looking at the change in the delay amount, one packet is discarded when 1000 packets for 20 seconds are accumulated. Thereby, the packet size of 20 msec is delayed and recovered. Thereafter, voice packets are sequentially accumulated, and one packet is discarded every time 1000 packets are added and accumulated. If voice packets are further accumulated and the buffer size exceeds 500 msec, it is processed as a packet loss.

  In the above embodiment, the voice packet signal receiving apparatus according to the present invention identifies the terminal type of a voice communication terminal such as a VoIP wireless terminal, and performs fluctuation compensation according to the optimum control parameter according to the difference in the terminal type. . Furthermore, by setting a packet discard rate and a delay recovery amount as control parameters, it becomes possible to compensate for a fixed delay that occurs as a result of fluctuation compensation.

  The voice packet signal receiving apparatus according to the present invention is not limited to voice communication using the VoIP technology, and can be applied to various voice packet signal receiving apparatuses that perform voice communication by packet communication via a packet transmission network.

It is a block diagram which shows the conventional VoIP system. It is an Example of this invention, and is a block diagram which shows the whole structure containing an audio | voice packet signal receiver. It is a figure which shows the example of a setting of the control parameter table shown in FIG. It is a flowchart which shows the process sequence performed in the structure shown by FIG. It is a graph which shows the time change of the delay amount of the audio | voice packet in a receiving buffer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 VoIP wireless terminal 11 VoIP wired terminal 20 Wireless terminal accommodating apparatus 21 Wired terminal accommodating apparatus 30 IP network 40 Voice packet signal receiving apparatus 41 Receiving part 42 Reception buffer 43 Non-packetizing part 44 Voice expansion decoding part 45 Terminal type identification part 46 Control Parameter table 47 Receive buffer controller

Claims (4)

A voice packet signal receiving apparatus including a receiving unit that receives voice packet signals arriving from a plurality of voice communication terminals via a packet transmission network, and a fluctuation compensating unit that performs fluctuation compensation on the received voice packet signals. And
Whether the terminal type of the voice communication terminal is a wired terminal type or a wireless terminal type based on identification information of a communication standard included in the received voice packet signal between the voice communication terminal and the packet transmission network Terminal type discriminating means for discriminating;
Control parameter supply means for supplying a fluctuation control parameter corresponding to the determined terminal type to the fluctuation compensator, and
The voice packet signal receiving apparatus, wherein the fluctuation compensator performs a fluctuation compensation operation according to a supplied control parameter. The fluctuation compensator prepares a reception buffer having a size corresponding to a packet accumulation amount included in the fluctuation control parameter, and sequentially accumulates each of a plurality of packets of an incoming voice packet signal in the reception buffer when the arrival buffer arrives. The voice packet signal receiving apparatus according to claim 1, wherein each of the accumulated packets is read at a constant period. The voice packet signal reception according to claim 1, wherein the fluctuation compensator includes packet discarding means for discarding at least one of the accumulated packets in accordance with a packet discard rate included in the fluctuation control parameter. apparatus. The fluctuation compensator determines a packet discard rate based on a delay recovery amount included in the fluctuation control parameter, and discards at least one packet out of the accumulated packets according to the determined packet discard rate, thereby generating a voice packet signal 2. The voice packet signal receiving apparatus according to claim 1, further comprising delay recovery means for recovering the delay of the voice packet signal.

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