Voice repeater and multiplexer

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

In the present invention, in voice communication between voice terminals connected to a telephone network, when a part of the voice communication section is relayed by the IP network, the voice signal is multiplexed and multicast communication or broadcast communication is performed to a plurality of destinations. The present invention relates to a relay / multiplexing device that is relayed by using.

【0002】

[Conventional technology]

Conventionally, using TCP / IP or UDP / IP, one session is established for each voice communication by unicast communication, and one-to-one communication is performed between two relay devices. Further, in order to reduce the communication overhead between relay devices, there is known a method of multiplexing several voice packets of the same destination into one packet.

【0003】

In addition, for one-to-one communication of unicast communication, multicast communication (reference: IETF RFC1112) that performs one-to-many communication to a specific group using a special group address, and network using a broadcast address. There is broadcast communication that performs one-to-many communication to all the above devices.

【0004】

[Problems to be Solved by the Invention]

In an IP telephone composed of a telephone network, a voice terminal connected to the telephone network, an IP network, and a relay device connected to the telephone network and the IP network, analog voice signals and digital voice signals are exchanged with each other. In order to convert to, the conventional PCM method requires a data amount of 64 kbps. However, with the recent high-compression conversion method, the size is reduced to about 1/10 of 6 to 8 kbps, and with the ITU-T G.723.1 method, which is currently the mainstream for IP phones, the size of one voice packet is only 24 bytes. .. On the other hand, in IP phones, voice packets are transmitted using RTP / UDP / IP, but when actually transmitted, a header is added and transmitted, but the size of the header is 40 (= 12 + 8 + 20). It is a byte (reference: IETF RFC 1889). Then, when the above-mentioned high compression conversion method is used, there is a problem that the size of the header becomes larger than the amount of data actually transmitted, resulting in an overhead of transmission.

【0005】

Further, conventionally, using TCP / IP or UDP / IP, one session is established for each voice communication by unicast communication, and one-to-one communication is performed between two relay devices. In this method, when multiple sessions are established between two relay devices, packet relay processing at the router device and voice packet transmission / reception processing at the IP phone relay device are performed due to the increase in the number of voice packets. There is a problem that the load increases. To solve this problem, a method of multiplexing voice packets to reduce the number of voice packets can be considered. However, since unicast communication has been used in conventional IP telephones, in the case of multiplexing, it is necessary to multiplex for each same destination and send it to the destination by unicast communication. In this method, it is necessary to prepare as many multiplexing buffers as there are destinations, secure a multiplexing buffer when communication with a new destination occurs, and release the multiplexing buffer when communication with a certain destination disappears. .. Such multiplexing buffer management has a problem that it becomes a processing load of the voice relay / multiplexing device.

【0006】

In the IP network, the size of packets that can be transmitted is limited by the MTU (Max Transfer Unit). In addition, a packet with a long packet length causes a delay in relaying at the router. Therefore, if the packet length is increased due to multiplexing, there is a problem that transmission is not possible or transmission delay increases.

【0007】

Further, by multiplexing many voice packets, the transmission overhead is reduced, but conversely, the processing time for multiplexing increases, and the end-to-end delay time increases. There is.

【0008】

A first object of the present invention is to reduce the ratio of the header size to the size of the data to be actually transmitted by concatenating and multiplexing the voice data, and to reduce the transmission overhead. It is to provide a relay and multiplexing device.

【0009】

A second object of the present invention is to multiplex data regardless of the destination and use multicast communication to address a specific group of relay / multiplexing devices, or to use broadcast communication to perform all voice relay / multiplexing. It is an object of the present invention to provide a voice relay / multiplexing device provided with a transmission means for eliminating a processing load of preparing and managing a multiplexing buffer for each destination by transmitting to the device.

【0010】

A third object of the present invention is to provide a voice relay / multiplexing device provided with means for avoiding transmission limitation by the MTU and suppressing an increase in communication delay by a router by limiting the packet length to less than a specified length. To provide.

【0011】

A fourth object of the present invention is to provide a voice relay / multiplexing device provided with means for suppressing an increase in communication delay due to multiplexing processing by limiting the multiplexing interval of voice packets.

【0012】

[Means for solving problems]

In order to solve the above problems, the present invention comprises a telephone network, a voice terminal connected to the telephone network, an IP network, and a plurality of relay / multiplexing devices connected to the telephone network and the IP network. The voice signal exchanged between two voice terminals connected to the telephone network in the communication system is relayed from the telephone network to the IP network, and the relayed voice signal is relayed from the IP network to the telephone network. A voice relay / multiplexing device that divides a voice signal input from a telephone line accommodated by the device into voice data of an arbitrary size and adds telephone destination information to the voice data to generate a voice packet. A packet generating means, a concatenated packet generating means that concatenates an arbitrary number of voice packets to generate one concatenated packet, a transmitting means that transmits the concatenated packet to the IP network, and a receiving means that receives the concatenated packet from the IP network. A concatenated packet dividing means that divides the concatenated packet into voice packets constituting the concatenated packet, and the apparatus that separates the voice packet into telephone destination information and voice data and uses the destination information to separate the voice data. It is provided with a means for outputting a voice signal to an arbitrary telephone line to be accommodated. As a result, by multiplexing by concatenating voice packets into a concatenated packet, RTP / UDP with respect to the size of the concatenated packet is compared with the ratio of the size of the RTP / UDP / IP header to the size of the voice packet. It is possible to reduce the size ratio of the / IP header and reduce the transmission overhead.

【0013】

Further, in the transmission means, instead of transmitting by unicast communication, transmission is performed to a specific group of relay / multiplexing devices using multicast communication, or to all relay / multiplexing devices using broadcast communication. By multiplexing voice packets and sending them to the relay / multiplexing device regardless of the destination, a multiplexing buffer must be prepared for each destination, and the buffer must be managed in conjunction with the creation and disappearance of connections. It is possible to eliminate the processing load that must be done.

【0014】

In addition, by providing a packet length limiting means that limits the packet length to less than a predetermined length, the packet length is limited to less than the specified length, the transmission limitation by the MTU in the IP network is avoided, and the transmission delay by the router is avoided. It is possible to suppress the increase.

【0015】

Further, by providing the packet generation interval control means for suppressing the multiplexing interval to a predetermined time interval or less, it is possible to suppress an increase in communication delay due to the multiplexing process.

【0016】

The hardware configuration includes a telephone network, a voice terminal connected to the telephone network, an IP network, and a plurality of voice relay / multiplexing devices connected to the telephone network and the IP network. In a communication system, a voice signal exchanged between two voice voice terminals connected to the telephone network is relayed from the telephone network to the IP network, and the relayed voice signal is relayed from the IP network to the telephone network. A telephone network interface for connecting to the telephone network, an IP network interface for connecting to the IP network, a memory for storing data and programs, and a secondary storage device, which is a relay / multiplexing device. The telephone network interface includes a CPU for executing the program and a control console for controlling the programs, and the telephone network interface receives a voice signal from the telephone network and outputs a voice signal to the telephone network to obtain the IP. The network interface receives a concatenated packet from the IP network and transmits a concatenated packet to the IP network, and the memory and the secondary storage device are input by the telephone network interface and transmitted by the IP network interface. The voice data converted from the voice signal is stored for the purpose of storing the voice data, and the voice data received by the IP network interface and converted into the voice signal for output by the telephone network interface is stored. A program that realizes a process of generating a concatenated packet from an input voice signal and a process of reproducing a voice signal from the received concatenated packet is stored.

【0017】

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described with reference to FIGS. 1 to 15.

【0018】

FIG. 1 shows a configuration diagram of a communication system according to the present embodiment. 102 is a telephone network, 103 is an IP network, and the voice relay / multiplexing device 201 performs voice relay and multiplexing between the telephone network 102 and the IP network 103. The voice terminal 101 is a voice terminal connected to the telephone network 102. In the present embodiment, the voice signal exchanged between the two voice terminals connected to the telephone network is converted into a voice packet, further multiplexed to generate a concatenated packet 104, and connected to the telephone network and the IP network. The voice relay / multiplexing device 201 relays the relayed packet from the telephone network to the IP network by IP multicast communication or IP broadcast communication, and another voice relay / multiplexing device converts the relayed packet into a voice signal on the telephone network. Relay to.

【0019】

Figure 2 shows the hardware configuration of the audio relay / multiplexing device. In FIG. 2, the said in a communication system composed of a telephone network, a voice terminal connected to the telephone network, an IP network, and a plurality of relay / multiplexing devices connected to the telephone network and the IP network. A voice relay / multiplexing device 201 that relays a voice signal exchanged between two voice terminals connected to a telephone network from the telephone network to the IP network and relays the relayed voice signal from the IP network to the telephone network. Is a telephone network interface 205 for connecting to a telephone network, an IP network interface 206 for connecting to an IP network, and a memory 203 and two for storing data and programs for voice relay and multiplexing processing 301. It includes a secondary storage device 204 and a central processing device 202 that executes the processing.

【0020】

The telephone network interface 205 receives a voice signal from the telephone network 102 and outputs a voice signal to the telephone network, and the IP network interface 206 receives a concatenated packet from the IP network 103 and also to the IP network. The concatenated packet is transmitted, and the memory 301 and the secondary storage device 204 store the voice data input by the telephone network interface 205 and converted from the voice signal for transmission by the IP network interface 206, and also the IP network interface. It stores voice data that is received by 206 and converted to a voice signal for output by telephone network interface 205, and also stores a program that realizes voice relay and multiplexing processing 301. The processing in the voice relay / multiplexing device can be processed by the central processing unit 202.

【0021】

FIG. 3 shows the software configuration of the audio relay / multiplexing process 301. In FIG. 3, the voice relay / multiplexing process 301 includes a telephone network interface control unit 310 that controls the telephone network interface 205, an IP network interface control unit 311 that controls the IP network interface 206, and voice from the telephone network to the IP network. It is composed of a packet transmission processing unit 302 that relays the above, a packet reception processing unit 307 that relays voice from the IP network to the telephone network, a telephone destination processing unit 305, and a group destination processing unit 306.

【0022】

The packet transmission processing unit 302 includes a voice packet generation unit 303 having a function of generating a voice packet based on a voice signal input from the telephone network interface control unit 310 and the telephone destination information obtained from the telephone destination processing unit 305. Two or more voice packets obtained by the voice packet generation unit 303 are concatenated to generate a concatenated packet, and transmission processing is performed to the IP network interface control unit 311 to the group address obtained by the group destination processing unit 306. It is composed of a concatenated packet generation unit 309 having a function.

【0023】

The packet reception processing unit 307 uses the concatenated packet separation unit 309 that decomposes the concatenated packet received by the IP network interface control unit 311 into the voice packets constituting the concatenated packet and the voice packet obtained by the concatenation packet separation unit 309. It is composed of a voice packet analysis unit 308 that takes out voice data and telephone destination information, passes the telephone destination information to the telephone destination processing unit 305, and outputs a voice signal corresponding to the telephone destination information to the telephone network interface control unit 310. Will be done.

【0024】

The telephone address processing unit 305 exchanges telephone address information with the telephone network interface control unit 310, and manages the caller's telephone number and the destination telephone number in correspondence with each other.

【0025】

The group address processing unit 306 exchanges telephone destination information with the telephone destination processing unit 305, and manages the telephone destination information in association with the group address information for IP multicast communication or the broadcast address information for IP broadcast communication. , Exchanges group address information or broadcast address information with IP network interface control unit 311.

【0026】

FIG. 4 shows the packet structure of the voice packet generated by the voice packet generation unit 306. The voice packet is composed of voice data 403 obtained by dividing the voice signal obtained from the telephone network interface control unit 310 into a predetermined data length (for example, 20 bytes) and telephone destination information obtained by the telephone destination processing unit 305. Will be done. The telephone address information is composed of a caller's telephone number 401 and a destination telephone number 402.

【0027】

FIG. 5 shows the packet structure of the concatenated packet generated by the concatenated packet generation unit 309. The concatenated packet is composed of a sequence of one or more voice packets 502 generated by the voice packet generation unit 306 and a concatenated number storage unit 501 that stores the total number of voice packets concatenated to the concatenated packet.

【0028】

FIG. 6 shows a flowchart of the processing operation of the packet transmission processing unit 302. In FIG. 6, the packet transmission processing unit 302 first initializes the concatenated packet generation buffer (step 602). Next, it is determined whether or not the voice packet concatenation process is completed, for example, by whether or not all the voice packets generated from the telephone network interface in use are concatenated (step 603), and if so, the process is completed. If not, the voice packet generation unit 306 generates a voice packet (step 701) and adds it to the end of the concatenated packet generation buffer (step 604). If it has ended, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 605), and the concatenated packet is addressed to the group address obtained by the group address processing unit 306. Send (step 606).

【0029】

FIG. 7 shows a flowchart of the processing operation of the voice packet generation processing 701. In FIG. 7, the voice packet generation unit 303 divides the voice signal obtained from the telephone network interface into predetermined data lengths (for example, 20 bytes) to generate voice data (step 702), and the telephone destination processing unit. Add the telephone destination information composed of at least the caller's telephone number and the destination telephone number obtained in 305 (step 703).

【0030】

FIG. 8 shows a flowchart of the processing operation of the packet reception processing unit 307. In FIG. 8, the packet reception processing unit 307 determines whether all voice packets have been extracted from the concatenated packet (step 802). If there is an unextracted voice packet, one voice packet is extracted (step 803), the voice packet analysis unit analyzes the voice packet, and the voice signal is reproduced from the telephone line interface (step 901). If all voice packets have been taken out, the process ends (step 804).

【0031】

FIG. 9 shows a flowchart of the processing operation of the voice packet analysis processing 901. In FIG. 9, the voice packet analysis unit 306 extracts the telephone destination information from the voice packet (step 902), and is the voice packet to be processed by the self-voice relay device from the call destination telephone number included in the telephone destination information? Whether or not it is determined (step 903), and if it is a voice packet to be processed, voice data is passed to the telephone network interface control unit 310 (step 904).

【0032】

According to the present embodiment, by multiplexing by concatenating voice packets into a concatenated packet, RTP with respect to the size of the concatenated packet is compared with the ratio of the size of the RTP / UDP / IP header to the size of the voice packet. It is possible to reduce the size ratio of the / UDP / IP header, and it is possible to reduce the transmission overhead.

【0033】

In addition, the packet transmission processing unit 202 multiplexes the voice packets of all destinations by transmitting using IP multicast communication or IP broadcast communication instead of transmitting by IP unicast communication, and is a voice relay / multiplexing device. By transmitting to 301, it is possible to prepare a multiplexing buffer for each destination and reduce the processing load that must manage the buffer in conjunction with the creation and deletion of connections.

【0034】

FIG. 10 shows a software configuration of a voice relay / multiplexing process 1001 provided with a packet transmission processing unit 1002 with a packet length limiting means, which further includes a means for limiting a concatenated packet to a predetermined packet length or less in the packet transmission processing unit 302. Is shown. In FIG. 10, the voice relay / multiplexing process 1001 provided with the packet transmission processing unit 1002 with the packet length limiting means is the telephone network interface control unit 310 that controls the telephone network interface 205 and the IP network that controls the IP network interface 206. Interface control unit 311, packet transmission processing unit 1002 with packet length limiting means for relaying voice from the telephone network to the IP network, packet reception processing unit 307 for relaying voice from the IP network to the telephone network, and telephone destination processing unit 305. And the group destination processing unit 306.

【0035】

The packet transmission processing unit 1002 with packet length limiting means has a function of generating a voice packet based on the voice signal input from the telephone network interface control unit 310 and the telephone destination information obtained from the telephone destination processing unit 305. One or more voice packets obtained by the generation unit 303 and the voice packet generation unit 303 are concatenated to generate a concatenated packet, and the IP network interface control unit 311 is addressed to the group address obtained by the group destination processing unit 306. It is composed of a concatenated packet generation unit 309 having a function of performing transmission processing, and a packet length limiting unit 1003 that limits the packet length of the concatenated packet to a predetermined packet length or less.

【0036】

FIG. 11 shows a flowchart of the processing operation of the packet transmission processing unit 1002 with the packet length limiting means. In FIG. 11, the packet transmission processing unit 1002 with the packet length limiting means first initializes the concatenated packet generation buffer (step 1102). Next, it is determined whether or not the voice packet concatenation process is completed, for example, by whether or not all the voice packets generated from the telephone network interface in use are concatenated (step 1103), and if so, the process is completed. If not, by concatenating the voice packets, it is determined whether the packet length of the concatenated packet exceeds the predetermined packet length (for example, 500 bytes) (step 1104). If the packet length does not exceed, the voice packet generation unit 306 generates a voice packet (step 701), adds it to the end of the concatenated packet generation buffer (step 1105), and returns to step 1103. In step 1104, if the packet length exceeds, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1106), and the concatenated packet is stored in the group address processing unit 306. Send to (step 1107) and return to step 1102. If the concatenation process is completed in step 1103, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1108), and the concatenated packet is obtained by the group address processing unit 306. Send to the group address (step 1109).

【0037】

According to the present embodiment, in addition to the effect of the packet transmission processing unit 302, the packet length of the concatenated packet generated by concatenating the voice packets can be limited to less than a predetermined length, and the IP network can be used. It is possible to suppress the influence of the limit of the transmittable packet length by the MTU and the relay delay in the router of the packet with a long packet length.

【0038】

Further, the processing method of the packet transmission processing unit 1002 with the packet length limiting means is effective not only for voice relay by IP multicast communication and IP broadcast communication but also for voice relay by IP unicast communication.

【0039】

FIG. 12 shows a software configuration of a voice relay / multiplexing process 1201 provided with a packet transmission processing unit 1202 with a generation interval adjusting means, which is further provided with a means for generating a concatenated packet at a predetermined time interval in the packet transmission processing unit 302. Shown. In FIG. 12, the voice relay / multiplexing process 1201 provided with the packet transmission processing unit 1202 with the generation interval adjusting means includes the telephone network interface control unit 310 that controls the telephone network interface 205 and the IP network that controls the IP network interface 206. Interface control unit 311, packet transmission processing unit 1202 with generation interval adjusting means for relaying voice from the telephone network to the IP network, packet reception processing unit 307 for relaying voice from the IP network to the telephone network, and telephone destination processing unit 305. And the group destination processing unit 306.

【0040】

The packet transmission processing unit 1202 with the generation interval adjusting means has a function of generating a voice packet based on the voice signal input from the telephone network interface control unit 310 and the telephone destination information obtained from the telephone destination processing unit 305. One or more voice packets obtained by the generation unit 303 and the voice packet generation unit 303 are concatenated to generate a concatenated packet, and the IP network interface control unit 311 is addressed to the group address obtained by the group destination processing unit 306. It is composed of a concatenated packet generation unit 309 having a function of performing transmission processing, and a generation interval control unit 1203 that limits the generation interval of concatenated packets to a predetermined time interval or less.

【0041】

FIG. 13 shows a flowchart of the processing operation of the packet transmission processing unit 1202 with the generation interval adjusting means. In FIG. 13, the packet transmission processing unit 1202 with the generation interval adjusting means first initializes the concatenated packet generation buffer (step 1302). Next, it is determined whether or not the voice packet concatenation process is completed, for example, by whether or not all the voice packets generated from the telephone network interface in use are concatenated (step 1303), and if so, the process is completed. If not, it is determined whether or not a predetermined time (for example, 30 milliseconds) or more has passed since the last concatenated packet was transmitted (step 1304). If time has passed, the voice packet generator 306 generates a voice packet (step 701), adds it to the end of the concatenated packet generation buffer (step 1305), and returns to step 1303. In step 1304, if time has passed, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1306), and the concatenated packet is obtained by the group address processing unit 306. Send to the group address (step 1307) and return to step 1302. If the concatenation process is completed in step 1303, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1308), and the concatenated packet is obtained by the group address processing unit 306. Send to the group address (step 1309).

【0042】

According to the present embodiment, in addition to the effect of the packet transmission processing unit 302, it is possible to suppress an increase in communication delay due to the multiplexing process by further limiting the generation interval of the concatenated packet for multiplexing the voice packet. It becomes.

【0043】

Further, the processing method of the packet transmission processing unit 1202 with the generation interval adjusting means is effective not only for voice relay by IP multicast communication and IP broadcast communication but also for voice relay by IP unicast communication.

【0044】

FIG. 14 shows an audio system including a packet length limiting means and a packet transmission processing unit 1402 with a generation interval adjusting means, which further includes a means for generating a concatenated packet at a predetermined time interval in the packet transmission processing unit 1002 with a packet length limiting means. The software configuration of the relay / multiplexing process 1401 is shown. In FIG. 14, the voice relay / multiplexing process 1401 provided with the packet transmission processing unit 1402 with the packet length limiting means and the generation interval adjusting means includes the telephone network interface control unit 310 that controls the telephone network interface 205 and the IP network interface 206. IP network interface control unit 311 that controls, packet transmission processing unit 1402 with packet length limiting means and generation interval adjusting means that relays voice from the telephone network to the IP network, and packet reception that relays voice from the IP network to the telephone network. It is composed of a processing unit 307, a telephone destination processing unit 305, and a group destination processing unit 306.

【0045】

The packet transmission processing unit 1402 with the packet length limiting means and the generation interval adjusting means generates a voice packet based on the voice signal input from the telephone network interface control unit 310 and the telephone destination information obtained from the telephone destination processing unit 305. A voice packet generation unit 303 having a function and one or more voice packets obtained by the voice packet generation unit 303 are concatenated to generate a concatenated packet, and an IP network interface is sent to the group address obtained by the group destination processing unit 306. The concatenated packet generation unit 309 having a function to perform transmission processing to the control unit 311, the packet length limiting unit 1003 that limits the packet length of the concatenated packet to a predetermined packet length or less, and the concatenated packet generation interval in advance. It is composed of a generation interval control unit 1203 that limits the time interval to the specified time or less.

【0046】

FIG. 15 shows a flowchart of the processing operation of the packet transmission processing unit 1402 with the packet length limiting means and the generation interval adjusting means. In FIG. 15, the packet transmission processing unit 1402 with the packet length limiting means and the generation interval adjusting means first initializes the concatenated packet generation buffer (step 1502). Next, it is determined whether or not the voice packet concatenation process is completed, for example, by whether or not all the voice packets generated from the telephone network interface in use are concatenated (step 1503), and if so, the process ends. If not, it determines whether the packet length of the concatenated packet exceeds a pre-specified packet length (for example, 500 bytes) by concatenating the voice packets (step 1504). If the packet length does not exceed, it is determined whether or not a predetermined time (for example, 30 milliseconds) or more has passed since the last concatenated packet was transmitted (step 1505). If the time has not elapsed, the voice packet generation unit 306 generates a voice packet (step 701), adds it to the end of the concatenated packet generation buffer (step 1506), and returns to step 1503. If the packet length is exceeded in step 1504, or if the time has elapsed in step 1505, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1507). The concatenated packet is transmitted to the group address obtained by the group address processing unit 306 (step 1508), and the process returns to step 1502. If the concatenation process is completed in step 1503, the total number of concatenated voice packets is stored in the concatenated number storage unit 501 of the concatenated packet (step 1509), and the concatenated packet is obtained by the group address processing unit 306. Send to the group address (step 1510).

【0047】

According to the present embodiment, in addition to the effect of the packet transmission processing unit 1002 with the packet length limiting means, the communication delay due to the multiplexing processing is increased by limiting the generation interval of the concatenated packet for multiplexing the voice packet. It becomes possible to suppress it.

【0048】

Further, the processing method of the packet transmission processing unit 1402 with the packet length limiting means and the generation interval adjusting means is effective not only in the voice relay by IP multicast communication and IP broadcast communication but also in the voice relay by IP unicast communication.

【0049】

[Effect of the invention]

According to the present invention, by concatenating and multiplexing audio data, it is possible to reduce the ratio of the size of the RTP / UDP / IP header to the size of the data to be actually transmitted, and to reduce the transmission overhead. ..

【0050】

In addition, by multiplexing the data of all destinations and transmitting them using broadcast communication (IP multicast communication or IP broadcast communication), it is possible to eliminate the processing load of preparing and managing a multiplexing buffer for each destination. It will be possible.

【0051】

Further, by limiting the packet length to less than the specified length, it is possible to avoid the transmission restriction by the MTU and suppress the increase in the transmission delay by the router. This is effective not only for voice relay by IP multicast communication and IP broadcast communication, but also for voice relay by IP unicast communication.

【0052】

Further, by limiting the multiplexing interval of voice packets, it is possible to suppress an increase in communication delay due to the multiplexing process. This is effective not only for voice relay by IP multicast communication and IP broadcast communication, but also for voice relay by IP unicast communication.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram of a communication system.

[Figure 2]

It is a block diagram of the audio relay and multiplexing apparatus.

[Fig. 3]

It is a block diagram of audio relay and multiplexing processing.

[Fig. 4]

It is explanatory drawing of the packet structure of a voice packet.

[Fig. 5]

It is explanatory drawing of the packet structure of the concatenated packet.

[Fig. 6]

It is a flowchart of the processing operation of a packet transmission processing part.

[Fig. 7]

It is a flowchart of the processing operation of a voice packet generation part.

[Fig. 8]

It is a flowchart of the processing operation of a packet reception processing part.

[Fig. 9]

It is a flowchart of the processing operation of a voice packet analysis part.

[Fig. 10]

It is a functional block diagram of the voice relay and multiplexing apparatus provided with the packet transmission processing part with the packet length limiting means.

[Fig. 11]

It is a flowchart of the processing operation of the packet transmission processing part with the packet length limiting means.

[Fig. 12]

It is a functional block diagram of the voice relay and multiplexing apparatus provided with the packet transmission processing part with the generation interval adjusting means.

[Fig. 13]

It is a flowchart of the processing operation of the packet transmission processing unit with the generation interval adjustment means.

[Fig. 14]

It is a functional block diagram of the voice relay and multiplexing apparatus provided with the packet transmission processing unit with the packet length limiting means and the generation interval adjusting means.

[Fig. 15]

It is a flowchart of the processing operation of the packet transmission processing unit with the packet length limiting means and the generation interval adjusting means.

[Explanation of symbols]

101 ... voice terminal, 102 ... telephone network, 103 ... IP network, 201 ... voice relay and multiplexing device.