JP4452193B2 - Terminal - Google Patents

Description

This invention relates to a terminal capable of suppressing multiple terminals Call Cost between, in particular, relates to a multi-party call is available terminals.

  2. Description of the Related Art Conventionally, an IP phone is known as a device capable of making a call using an IP (Internet Protocol) network. In addition, not only a two-party call but also a multi-party audio conference system and a TV conference system are known as those using an IP network. Such a telephone using the IP network has an advantage that the call cost can be reduced as compared with the case where the public telephone network is used. However, when the IP network is congested, the communication data cannot be preferentially transferred and the packet is not transferred. Is discarded (packet loss occurs), so that quality degradation such as voice interruption may occur.

Therefore, a voice communication apparatus that can cope with a case where the communication quality of the IP network deteriorates has been proposed (see, for example, Patent Document 1). The apparatus disclosed in Japanese Patent Laid-Open No. 2004-228561 is used when an extension telephone accommodated in one private branch exchange performs voice communication with an extension telephone accommodated in the other private branch exchange via the IP network. However, when the traffic state of the IP network is monitored and it is determined that the communication quality of the IP network has deteriorated, the communication is switched to the public telephone network as a backup line. As a result, even if the communication cost is somewhat sacrificed, it is possible to maintain good communication quality.
JP 2000-354071 A (0011-0015, FIG. 1)

  However, the apparatus disclosed in Patent Document 1 is based on the premise that a private branch exchange monitors the traffic state of the IP network and switches the line according to the state. Therefore, when each telephone outputs communication data, it does not monitor the state of IP network traffic. When communication data is output to a plurality of telephones at the same time as in multi-party calls, Since the amount of traffic is exceeded, there is a problem that it cannot be applied to multi-party calls. Furthermore, when the communication quality of the IP network between two points deteriorates during use, the two private branch exchanges switch to the public telephone network, so that both sides are busy and the backup line cannot be quickly established. is there. In addition, when a wireless telephone is used, there is a problem that a backup line is not connected if the quality of the IP network does not deteriorate even if the radio wave condition is bad.

  In addition, for example, in the studio or sub-adjustment room of a broadcasting station, the functions of the income device used for business communication can be expanded and used at a relay site or between the sub-adjustment room and the relay site. It is demanded to be used for business communication.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a terminal capable of controlling multi-party calls with high quality while suppressing costs.

In order to achieve the above object, the terminal according to claim 1 of the present invention multiplexes communication data transmitted from a plurality of transmission sources other than the predetermined transmission source and returns the multiplexed communication data to the predetermined transmission source. A terminal for transmitting / receiving communication data to / from other terminals by connecting to the multiplexing means via an IP network or a public telephone network, comprising: a transmission path switching means; a transmission path switching control means; , And the transmission path switching control means includes a packet loss rate calculating means.

According to such a configuration, the mobile station by the transmission line switching control means, out of the loss rate of packets received via the I P network, and the radio wave strength that is received from an access point connected to the I P network Based on at least the packet loss rate , the transmission path switching means is controlled to switch the communication data transmission path from the IP network to the public telephone network. Then, the terminal switches between the IP network and the public telephone network as a transmission path for communication data by the transmission path switching means. Here, the packet loss rate is, for example, a ratio (for example, r / p) of a predetermined number (for example, p) of lost packets (for example, r) received via the IP network. Note that the number of lost packets can be calculated by using, for example, the sequence number of the header of the packet in RTP (Real-time Transport Protocol) .

Then, the terminal switches between the IP network and the public telephone network as a transmission path for communication data by the transmission path switching means. Then, when the terminal switches the transmission path of communication data such as voice to the public telephone network, the terminal sends an empty packet (silence, dummy data) to the multiplexing means via the IP network, and the IP network is switched from the multiplexing means. A packet (multiple signal) is received through the network. When the loss rate of packets received via the IP network is greater than a predetermined first predetermined value by the packet loss rate calculation means, the terminal dials up to the multiplexing means via the public telephone network. If the loss rate of packets received via the IP network is larger than the first predetermined value after the call of the public telephone network is established, the communication data is transmitted. A first switching control signal for outputting to the public telephone network is output to the transmission path switching means. Thereby, the transmission line switching means can output the communication data to the public telephone network.

In addition, the terminal according to claim 2 , the multiplexing means for multiplexing communication data transmitted from a plurality of transmission sources other than the predetermined transmission source and returning the multiplexed communication data to the predetermined transmission source, A terminal that transmits and receives communication data to and from other terminals by connecting via a telephone network, and includes a transmission path switching means and a transmission path switching control means, and transmission path switching control. The means includes radio wave intensity detection means.

According to such a configuration, the terminal uses the transmission path switching control unit to set at least the radio wave intensity between the loss rate of packets received via the IP network and the radio wave intensity received from the access point connected to the IP network. Based on this, the transmission path switching means is controlled so that the transmission path of the communication data is switched from the IP network to the public telephone network. Here, the radio wave intensity indicates the radio wave intensity in a wireless local area network (LAN) composed of a terminal and an access point. Then, the terminal switches between the IP network and the public telephone network as a transmission path for communication data by the transmission path switching means. Then, when the strength of the radio wave received from the access point becomes smaller than the second predetermined value determined in advance by the radio wave intensity detecting means, the terminal makes a dial-up connection to the multiplexing means via the public telephone network. A control signal for output to the transmission path switching means, and a duration of a state in which the intensity of the radio wave received from the access point is smaller than the second predetermined value after the call of the public telephone network is established exceeds a predetermined time. In this case, a first switching control signal for outputting communication data such as voice to the public telephone network is output to the transmission path switching means. Thereby, even when the communication quality of the IP network is good and the radio wave condition is bad, the communication data transmission path of this terminal can be quickly switched to the public telephone network, so that the communication quality can be kept good.

Also, the terminal according to claim 3 is the terminal according to claim 1 , wherein the transmission path switching control means includes a return control means.

  According to this configuration, in the terminal, after the first switching control signal is output to the transmission path switching unit by the return control unit, the loss rate of packets received via the IP network is equal to or less than the first predetermined value. If so, a second switching control signal for outputting communication data such as voice to the IP network is output to the transmission path switching means. Therefore, after the transmission path of communication data transmitted from a certain terminal to the multiplexing means is switched from the IP network to the public telephone network, the loss rate of packets received via the IP network is at a level that does not adversely affect the communication quality. When it returns, the transmission path can be switched to the IP network again.

According to a fourth aspect of the present invention , in the terminal according to the second aspect , the transmission path switching control means includes a return control means.

  According to such a configuration, the terminal is configured such that the strength of the radio wave received from the access point is greater than or equal to the second predetermined value after the first switching control signal is output to the transmission path switching unit by the return control unit. The second switching control signal for outputting communication data such as voice to the IP network is output to the transmission path switching means. Therefore, after the transmission path of communication data such as voice transmitted from a certain terminal to the multiplexing means is switched from the IP network to the public telephone network, the radio wave intensity from the access point to this terminal does not adversely affect the communication quality. When returning to the level, the transmission path can be switched to the IP network again.

ｔ＜ｔ₀の場合に、前記公衆電話網の接続を切断するための切断制御信号を前記伝送路切替手段に出力することを特徴とする。 Further, the terminal according to claim 5 is the terminal according to claim 3 , wherein the return control means is a predetermined unit before the loss rate of packets received via the IP network becomes larger than the first predetermined value. In a group of m packets composed of a number of packets, an average value of the number of lost packets is m ₀ , an unbiased variance is σ ₀ ² , and a predetermined number of times after the loss rate is greater than a first predetermined value in n sets of packet group consisting of a packet, the average number of packets lost and m _e, the unbiased variance and sigma _e ^2, the value of t distribution table when a significance level of _{α t 0 (m + n-} 2, α), and the t-test statistic represented by equation (1) is calculated as t,

When t <t ₀ , a disconnection control signal for disconnecting the connection of the public telephone network is output to the transmission path switching means.

According to this configuration, the terminal has a significant difference between the statistic when t <t ₀ , that is, after the packet loss rate exceeds the first predetermined value and the statistic in the steady state. If there is no call, disconnect the public telephone network.

The terminal according to claim 6 is the terminal according to claim 5 , wherein the return control means performs the first switching for outputting the communication data to the public telephone network when t ≧ t _0. A control signal is output to the transmission line switching means.

According to such a configuration, the terminal is configured such that when t ≧ t ₀ , that is, between the statistic after the packet loss rate of the IP network exceeds the first predetermined value and the statistic in the steady state. When there is a significant difference, the transmission path of communication data such as voice can be switched from the IP network to the public telephone network.

According to the first aspect of the present invention, communication is performed based on at least the packet loss rate among the loss rate of packets received via the IP network and the radio wave intensity received from the access point connected to the IP network. The transmission path switching means is controlled to switch the data transmission path from the IP network to the public telephone network. In addition, among the plurality of terminals, a terminal whose terminal loss rate of packets received via the IP network does not reach the first predetermined value (a terminal in which no failure has occurred) is connected to the transmission path of the IP network. Therefore, the communication cost can be kept to the minimum necessary. Furthermore, the terminal in which the failure has occurred can determine the communication quality, and can connect to an information processing apparatus that includes multiple means and is registered with a plurality of telephone numbers without being busy. Quality can be maintained.

According to the second aspect of the present invention, based on at least the radio wave intensity of the loss rate of packets received via the IP network and the radio wave intensity received from the access point connected to the IP network, the communication data The transmission path switching means is controlled to switch the transmission path from the IP network to the public telephone network. In addition, among a plurality of terminals, a terminal whose intensity of a radio wave received from an access point is not lower than the second predetermined value (a terminal in which no failure has occurred) remains in the IP network as a transmission path. Therefore, the communication cost can be kept to the minimum necessary. Furthermore, the terminal in which the failure has occurred can determine the communication quality, and can connect to an information processing apparatus that includes multiple means and is registered with a plurality of telephone numbers without being busy. Quality can be maintained.

According to the third or fourth aspect of the present invention, in the terminal where a failure has occurred, when the failure is avoided, the communication cost can be reduced by setting the transmission path again to the IP network.

According to the invention of claim 5 or claim 6 , in the terminal, after switching the communication data transmission path to the IP network, the public telephone network is disconnected based on the stability of the communication quality, or The transmission path of communication data such as voice is switched from the IP network to the public telephone network. Therefore, after returning to the IP network, it is possible to prevent unnecessary repetition of dial-up connection and disconnection to the public telephone network, thereby reducing communication costs.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
[Communication system configuration]
FIG. 1 is a configuration diagram of a communication system according to the first embodiment. As shown in FIG. 1, the communication system 1 includes a plurality of terminals 10 (10 a, 10 b) and an information processing device 30 connected to the transmission path 20, and enables multi-party calls between the terminals 10. It is what. The contact system 1 can be used, for example, for work of a broadcasting station.

  Although the details will be described later, the terminal 10 communicates data such as voice based on the loss rate of packets received via the IP network 21 or the radio wave intensity received from the access point 23 connected to the IP network 21. The communication path is switched from the IP network 21 to the public telephone network 22 and connected to the information processing device 30 to make a call with another terminal 10. The terminal 10 corresponds to a so-called wireless income device, and is used, for example, in a studio of a broadcasting station, an auxiliary adjustment room, a relay site, or the like.

  Here, a plurality (three in FIG. 1) of terminals 10a each have a communication connection number (hereinafter simply referred to as a number) assigned to the information processing apparatus 30 via the IP network 21, for example, “111”. Send a packet to Accordingly, the plurality of terminals 10a form a group “a” that can transmit and receive communication data to each other. This group “a” is targeted for a telephone station technician, for example. Similarly, a plurality (three in FIG. 1) of terminals 10b each send a packet to a number assigned to the information processing apparatus 30, for example, “222” via the IP network 21. Accordingly, the plurality of terminals 10b form a group “b” that can transmit and receive communication data to each other. This group “b” is targeted for a broadcast program director, for example.

  The transmission path 20 includes an IP (Internet Protocol) network 21 and a public telephone network 22, and an access point 23 is connected to the IP network 21. The access point 23 is installed relatively close to the place where the terminal 10 is used (for example, a range of several 10 to 100 m). The public telephone network 22 is, for example, a PHS line. Each terminal 10 forms a wireless LAN together with the access point 23.

  The information processing apparatus 30 multiplexes communication data transmitted from other than the transmission source among the communication data transmitted from each terminal 10 via the IP network 21 or the public telephone network 22, and sends the multiplexed data back to the transmission source. (N-1) A multi-party call based on the addition method is realized. The information processing apparatus 30 is assigned a number for connecting from the terminal 10, for example, “111”, “222”, and the like. Further, the information processing apparatus 30 is installed, for example, in a broadcast center for producing and transmitting a broadcast program. In the following embodiments, audio data is assumed as communication data, but it is needless to say that image data can also be communicated.

FIG. 2 is a block diagram illustrating a configuration of the terminal. As shown in FIG. 2, the terminal 10 includes an interface unit 11, an audio processing unit 12, an input / output switching unit 13, an IP processing unit 14, a switching control unit 15, an information processing unit 16, and a storage unit. 17.
The interface unit 11 inputs a voice of a caller or outputs a voice of another caller.

Here, a specific example of the interface unit 11 will be described with reference to FIG. FIG. 3 is an external view of an example of a terminal. As shown in FIG. 3, the terminal 10 includes a main body 40 and an interface unit 11 connected to the main body 40.
The interface unit 11 includes a headset including a microphone 41 and a speaker 42 that can be mounted on the head of a caller. The caller can input sound from the microphone 41 and listen to the sound of another caller from the speaker 42.
The main body unit 40 incorporates the voice processing unit 12, the input / output switching unit 13, the IP processing unit 14, the switching control unit 15 and the information processing unit 16 shown in FIG. Further, as shown in FIG. 3, the main body portion 40 is provided with a plurality of operation buttons 43 for executing general functions of the telephone such as a call function. In this, the operation button which outputs the control signal for switching the some number provided to the information processing apparatus 30 to the information processing part 16 according to operation is provided.

Referring to FIG. 2 again, the description of the configuration of the terminal 10 will be continued.
The audio processing unit 12 outputs a digital audio signal obtained by encoding the audio data output from the interface unit 11 to the input / output switching unit 13. The audio processing unit 12 decodes the digital audio signal sent from the input / output switching unit 13 and inputs the signal to the interface unit 11. The encoding method and decoding method of the speech processing unit 12 are, for example, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) standard G.264. 711 (information amount 64 kbps) and G.711. 729 (amount of information 8 kbps) can be used.

  The input / output switching unit (transmission path switching means) 13 switches whether the digital audio signal output from the audio processing unit 12 is transmitted through the IP network 21 or the public telephone network 22 under the control of the switching control unit 15. Is. The input / output switching unit 13 inputs the multiplexed audio signal transmitted through the IP network 21 to the audio processing unit 12. Further, when the transmission path is switched to the public telephone network 22, the multiplexed audio signal transmitted through the public telephone network 22 is input to the audio processing unit 12.

  The IP processing unit 14 transmits a packet obtained by converting the digital audio signal output from the input / output switching unit 13 into an IP data format to the IP network 21 via the access point 23. The IP processing unit 14 transmits a packet received from the IP network 21 via the access point 23 to the input / output switching unit 13 and the switching control unit 15. When the transmission path is switched to the public telephone network 22, the IP processing unit 14 transmits an empty packet (silence, dummy data) and transmits the received packet (multiplexed audio signal) to the switching control unit 15. Enter only.

  A switching control unit (transmission path switching control means) 15 controls switching of whether the digital audio signal output from the input / output switching unit 13 is output to the IP network 21 or the public telephone network 22 via the access point 23. To do. Note that the switching control unit 15 preferentially uses the IP network 21 over the public telephone network 22. The switching control unit 15 includes a packet loss rate calculation unit 151, a radio wave intensity detection unit 152, and a return control unit 153.

  The packet loss rate calculation unit (packet loss rate calculation means) 151 uses the header information from the information processing device 30 and the time information such as the packet reception interval and the loss rate of packets received via the IP network 21 in advance. The magnitude relationship with a predetermined set value (first predetermined value) is compared and determined, and a control signal is output to the input / output switching unit 13 based on the determination result. In other words, the packet loss rate calculation unit 151, when the number of consecutive predetermined number (p) of lost packets exceeds d (third predetermined value) (loss rate d / p is the first predetermined value), A control signal for dial-up connection to the information processing device 30 is output to the input / output switching unit 13 via the public telephone network 22. The constants d and p are set in advance. Further, the above determination result is output to the return control unit 153.

  Further, the packet loss rate calculation unit 151 has exceeded the d (third predetermined value) number of consecutive p packets received via the IP network since the call of the public telephone network 22 was established. In this case, the control signal P (first switching control signal) for outputting the digital audio signal output from the input / output switching unit 13 to the public telephone network 22 is output to the input / output switching unit 13. Note that the packet loss rate calculation unit 151 calculates the number of lost packets using, for example, the sequence number of the header portion of the packet in RTP (Real-time Transport Protocol). For example, if packets having sequence numbers “2” and “8” are missing from packets having consecutive integer values from “1” to “10”, the loss rate is 20%.

  The radio wave intensity detecting unit (radio wave intensity detecting means) 152 compares and determines the magnitude relationship between the intensity of the radio wave output from the access point 23 and a predetermined set value (second predetermined value). Based on this, a control signal is output to the input / output switching unit 13. That is, the radio wave intensity detection unit 152 causes the information processing apparatus 30 to make a dial-up connection via the public telephone network 22 when the intensity of the radio wave output from the access point 23 is lower than f (second predetermined value). Is output to the input / output switching unit 13. The constant f is set in advance. Further, the above determination result is output to the return control unit 153.

  In addition, the radio wave intensity detection unit 152 performs input / output switching when a state of radio wave intensity lower (smaller) than f (second predetermined value) continues for a predetermined time c after the call of the public telephone network 22 is established. A control signal P (first switching control signal) for outputting the digital audio signal output from the unit 13 to the public telephone network 22 is output. The constant c is set in advance.

  The return control unit (return control means) 153 receives the control signal P (first switching control signal) from the packet loss rate calculation unit 151 or the radio wave intensity detection unit 152 (the digital output from the input / output switching unit 13). After the transmission path of the audio signal is switched from the IP network 21 to the public telephone network 22, the control signal is switched between input and output based on the determination signals output from the packet loss rate calculation unit 151 and the radio wave intensity detection unit 152, respectively. This is output to the unit 13. That is, the return control unit 153 has the number of lost consecutive p packets received via the IP network 21 smaller than d (third predetermined value) and the strength of the radio wave output from the access point 23 is f. When the value is equal to or greater than (second predetermined value), a control signal Q (second switching control signal) for outputting the digital audio signal output from the input / output switching unit 13 to the IP network 21 via the access point 23. ) To the input / output switching unit 13.

  The return control unit 153 outputs the control signal Q (second switching control signal) (the transmission path of the digital audio signal output from the input / output switching unit 13 is switched from the public telephone network 22 to the IP network 21). After that, based on the determination signal output from the packet loss rate calculation unit 151, a t-test statistic to be described later is calculated, and based on the calculated statistic, the connection to the public telephone network 22 is disconnected. The cutting control signal is output to the input / output switching unit 13.

Here, the statistics calculated by the return control unit 153 will be described.
The packet loss rate calculation unit 151 determines whether the number of consecutive predetermined number (p) of packets received via the IP network 21 has exceeded d (third predetermined value). The signal is output to the return control unit 153.

The return control unit 153 receives m sets of packets including p packets before the number of consecutive predetermined number (p) of packets received via the IP network exceeds d (third predetermined value). In the group, the average value of the number of lost packets is set as m ₀ , and the unbiased variance is calculated as σ ₀ ² . In addition, the return control unit 153 includes n sets of packet groups including p packets after the number of consecutive p packets received via the IP network 21 exceeds d (a third predetermined value). , The average value of the number of lost packets is set as m _e , the unbiased variance is calculated as σ _e ² , and the t-test statistic t shown in Equation (1) is calculated. In the initial state of the call, since the average value m _{0 of the} number of lost packets and the unbiased variance σ ₀ ² are uncertain, they may be used by assigning a predetermined value.

Then, the return control unit 153 compares the t-test statistic t expressed by Equation (1) with the statistic t ₀ (m + n−2, α) calculated using the t distribution table stored in advance. To do. Here, α is a significance level. The statistic calculated using the t distribution table is, for example, t ₀ = 1.982 when m = n = 50 and α = 0.05.

When the statistic t of the t-test represented by the formula (1) is smaller than the statistic t ₀ (m + n−2, α) calculated using the t distribution table stored in advance (t <t ₀ ), The return control unit 153 determines that the packet loss rate is small, and outputs a disconnection control signal for disconnecting the connection of the public telephone network 22 to the input / output switching unit 13.

Also, when the t-test statistic t represented by the equation (1) is equal to or greater than a statistic t ₀ (m + n−2, α) calculated using a pre-stored t distribution table (t ≧ t ₀ ). The return control unit 153 determines that the packet loss rate is large, and outputs a control signal P (first switching control signal) for outputting the digital voice signal output from the input / output switching unit 13 to the public telephone network 22. To do.

The information processing unit (number switching unit) 16 is based on a control signal output from the operation button 43 provided in the main body unit 40 (see FIG. 3), and a plurality of numbers (for example, “ 111 ”or“ 222 ”), and the packet is transmitted to the read number via the IP network 21. Further, the information processing unit 16 reads the telephone number from the storage unit 17 when the input / output switching unit 13 switches the transmission path to the public telephone network 22 in accordance with the control of the switching control unit 15, and transmits the telephone number via the public telephone network 22. To call the read telephone number.
The storage unit (storage means) 17 stores a plurality of numbers (for example, “111” and “222”) assigned to the information processing apparatus 30 and a plurality of telephone numbers assigned to the information processing apparatus 30. is there. These numbers and telephone numbers may be registered in advance at the time of manufacture or may be input later.

Next, the configuration of the information processing apparatus 30 will be described with reference to FIG. 4 (refer to FIG. 1 as appropriate). FIG. 4 is a block diagram illustrating a configuration of the information processing apparatus. Here, for the sake of simplicity, the description will be made on the assumption that there are eight terminal units 10 and they are not divided into a plurality of groups (a group of all eight units).
The information processing apparatus 30 receives a packet via the IP network 21 or receives a digital voice signal via the public telephone network 22 and multiplexes (mixes) voices other than the source to each terminal 10. Are transmitted. As shown in FIG. 4, the information processing apparatus 30 includes a data conversion unit 31, a decoding unit 32, a mixing unit 33, an encoding unit 34, a packet conversion unit 35, a reception unit 36, and a transmission unit. 37.

The data converter 31 receives a packet via the IP network 21, converts it into compressed data corresponding to all the terminals 10 (eight in the example shown in FIG. 4) that output the packet to the IP network 21, and decodes the compressed data. Is output to the conversion unit 32.
The decoding unit 32 decodes each compressed data output from the data conversion unit 31 into a digital audio signal and outputs it to the mixing unit 33.

The mixing unit (multiplexing means) 33 is an audio signal to be transmitted to all the terminals 10 (eight in the example shown in FIG. 4), and the remaining terminals 10 excluding the transmitting terminal 10 (FIG. 4). In this example, a multiplexed audio signal is created by adding audio signals transmitted from 7). There are as many types of multiplexed audio signals as the number of terminals 10. Usually, when N is a signal obtained by adding all the audio signals A _{1 to} A ₈ transmitted from the eight terminals 10 through the IP network 21, the multiplexed audio signals are (NA- ₁ ) to (NA). ₈ ) 8 types.

When the terminal 10 switches the voice data transmission path from the IP network 21 to the public telephone network 22, the multiplexed voice signal is as follows. That is, for example, when two terminals 10 (referred to as 10 ₁ and 10 ₂ ) switch the transmission path of voice data from the IP network 21 to the public telephone network 22, the terminals 10 ₁ and 10 ₂ The empty packets A ₁ and A ₂ are transmitted through the IP network 21 and the voice signals A ₁ ′ and A ₂ ′ are transmitted through the public telephone network 22, respectively. In this case, the mixing unit 33 generates (NA ₁ ) and (NA ₂ ) as usual for the empty packets A ₁ and A ₂ as multiplexed audio signals. Accordingly, the terminals 10 ₁ and 10 ₂ acquire the multiplexed voice signals (NA ₁ ) and (NA ₂ ) through the IP network 21 and use them to monitor the number of lost packets and the like. become.

Also, the mixing unit 33 receives (N′−A ₁ ′) and (N′−A) as multiplexed audio signals for the audio signals A ₁ ′ and A ₂ ′ transmitted via the public telephone network 22. ₂ ′). Here, N 'is an audio signal _A 3 to A _8, which is transmitted via the IP network 21 from other six, the audio signal _A 1 is transmitted via the public telephone network _{22', A} 2 ' And a signal obtained by adding all of. As a result, the terminals 10 ₁ and 10 ₂ input the multiplexed voice signals (N′-A ₁ ′) and (N′-A ₂ ′) acquired through the public telephone network 22 to the voice processing unit 12. Then, the terminals 10 ₁ and 10 ₂ output clear voice.

Further, the mixing unit 33 generates (N′-A ₃ ) to (N′-A ₈ ) as multiplexed audio signals for the audio signals A _{3 to} A ₈ transmitted via the IP network 21. To do. Accordingly, the six terminals 10 other than the terminals 10 ₁ and 10 ₂ can acquire multiple audio signals including clear audio signals A ₁ ′ and A ₂ ′ transmitted via the public telephone network 22. it can.

The mixing unit 33 outputs a multiplexed voice signal to be transmitted to all the terminals 10 that output packets to the IP network 21 (eight units in the example shown in FIG. 4) to the encoding unit 34 and the public telephone network. Multiplex audio signals to be transmitted to all the terminals 10 that output digital audio signals to 22 (two of the eight in the example shown in FIG. 4) are output to the public telephone network 22.
For convenience of explanation, the mixing unit 33 is assigned one connection number (actually, there are a plurality of terminals as shown in FIG. 1) for the eight terminals 10 to communicate with each other. Yes.

The encoding unit 34 encodes multiplexed voice signals (eight types in the example shown in FIG. 4) that are output from the mixing unit 33 and transmitted to the IP network 21. The encoding method of the encoding unit 34 is, for example, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) standard G.264. 711 (information amount 64 kbps) and G.711. 729 (amount of information 8 kbps) can be used.
The packet conversion unit 35 transmits a packet obtained by converting the multiplexed voice signal (eight types in the example shown in FIG. 4) encoded by the encoding unit 34 into the IP data format to the IP network 21.

A telephone number is assigned to the receiving unit 36. The receiving unit 36 receives a call from the terminal 10 (receives a digital voice signal via the public telephone network 22), and receives the received digital voice signal. This is output to the mixing unit 33.
The transmission unit 37 receives all the multiplexed audio signals output from the mixing unit 33 via the public telephone network 22 and outputs all the digital audio signals to the public telephone network 22 (eight terminals in the example shown in FIG. 4). 2 of them). For example, a gateway may be used as an apparatus that shares the functions of the receiving unit 36 and the transmitting unit 37.

Next, the configuration of the information processing apparatus 30 when the terminals 10a and 10b are grouped as shown in FIG. 1 will be described with reference to FIGS.
In the information processing apparatus 30, two numbers “111” and “222” are assigned to the mixing unit 33 (see FIG. 4). That is, the mixing unit 33 is provided with two paths corresponding to the numbers “111” and “222”. These numbers are stored in the storage unit 17 (see FIG. 2) of the terminal 10. The receiving unit 36 and the transmitting unit 37 (see FIG. 4) of the information processing apparatus 30 can be set in any number of pairs. (However, one pair is shown in the example shown in FIG. 4). For example, when the information processing apparatus 30 has two telephone lines, they are expressed as receiving units 36a and 36b and transmitting units 37a and 37b. For example, telephone numbers T1 and T2 are assigned to the receiving units 36a and 36b, respectively. The telephone numbers T1 and T2 correspond to the numbers “111” and “222” assigned to the mixing unit 33 (see FIG. 4), respectively, and are stored in the storage unit 17 (see FIG. 2) of the terminal 10. Is done.

[Operation of communication system]
Next, a specific example of multi-party call in the communication system 1 according to the first embodiment will be described with reference to FIG. 1 (refer to FIG. 4 as appropriate).
The terminal 10 a normally transmits a packet to the number “111” assigned to the mixing unit 33 of the information processing apparatus 30 via the IP network 21. When the transmission path is switched to the public telephone network 22, the terminal 10a makes a call to the telephone number T1 assigned to the receiving unit 36a of the information processing apparatus 30. The receiving unit 36 a is connected to the number “111” of the mixing unit 33. Accordingly, the terminal 10a whose transmission path is switched to the public telephone network 22 can perform multi-party calls with other terminals 10a in the group “a”. In another terminal 10a in this case, the transmission path 20 may be maintained in the IP network 21, or the transmission path may be switched to the public telephone network 22.

  Similarly, the terminal 10 b normally sends a packet to the number “222” assigned to the mixing unit 33 of the information processing apparatus 30 via the IP network 21. When the transmission path is switched to the public telephone network 22, the terminal 10b makes a call to the telephone number T2 assigned to the receiving unit 36b of the information processing apparatus 30. The receiving unit 36 b is connected to the route of the number “222” of the mixing unit 33. Accordingly, the terminal 10b whose transmission path is switched to the public telephone network 22 can make a multi-party call with another terminal 10b in the group “b”.

  Further, normally, the terminal 10a that sends a packet to the number “111” sends a packet to the number “222” read from the storage unit 17 by the information processing unit 16 in response to an operation of a predetermined operation button. You can also. In this case, the terminal 10a can make a multi-party call with another terminal 10b in the group “b”. In the present embodiment, two numbers and two telephone numbers are assigned to the information processing apparatus 30, but the numbers are arbitrary.

[Terminal switching operation]
Next, the operation of the switching control unit 15 of the terminal 10 according to the first embodiment will be described with reference to FIG. FIG. 5 is a flowchart illustrating the operation of the switching control unit of the terminal. The switching control unit 15 performs the following operation.

  The switching control unit 15 uses the packet loss rate calculation unit 151 to determine whether the number of lost packets is “d” or more (step S1). When the number of lost packets is “d” or more (step S1: Yes), the switching control unit 15 inputs and outputs a control signal for controlling the packet loss rate calculation unit 151 to connect to the public telephone network 22. Output to the switching unit 13. As a result, the input / output switching unit 13 establishes a dial-up connection to the information processing apparatus 30 via the public telephone network 22 (step S2).

  The switching control unit 15 repeats the determination until the call is established (step S3). If the call is established (step S3: Yes), the packet loss rate calculation unit 151 then sets the packet loss number to “d”. It is determined whether or not this is the case (step S4). At this time, the packet loss rate calculation unit 151 uses time information such as header information from the information processing device 30 and a packet reception interval. When the number of lost packets is “d” or more (step S4: Yes), the switching control unit 15 uses the packet loss rate calculation unit 151 to control the communication data to be output to the public telephone network 22. P is output to the input / output switching unit 13 (step S5). As a result, the input / output switching unit 13 transmits communication data to the information processing device 30 via the public telephone network 22. In addition, the IP processing unit 14 transmits an empty packet to the information processing apparatus 30 via the IP network 21.

  If the number of lost packets is less than “d” in step S <b> 1 (step S <b> 1: No), the switching control unit 15 determines whether the radio field intensity is lower (smaller) than “f” by the radio field intensity detection unit 152. It is determined whether or not (step S10). When the radio wave intensity is “f” or more (step S10: No), the switching control unit 15 returns to step S1.

  On the other hand, when the radio field intensity is lower (smaller) than “f” (step S10: Yes), the switching control unit 15 inputs a control signal for controlling the radio field intensity detection unit 152 to connect to the public telephone network 22. Output to the output switching unit 13. As a result, the input / output switching unit 13 makes a dial-up connection to the information processing apparatus 30 via the public telephone network 22 (step S11). Then, the switching control unit 15 repeats the determination until the call is established (step S12), and if the call is established (step S12: Yes), the radio wave intensity detection unit 152 subsequently performs a radio wave lower than “f”. It is determined whether the intensity has continued for a predetermined time “c” (step S13).

  When the radio field intensity lower than “f” continues for a predetermined time “c” (step S13: Yes), the switching control unit 15 controls the radio field intensity detection unit 152 to output communication data to the public telephone network 22. Control signal P is output to the input / output switching unit 13 (step S5). As a result, the input / output switching unit 13 transmits communication data to the information processing device 30 via the public telephone network 22. In addition, the IP processing unit 14 transmits an empty packet to the information processing apparatus 30 via the IP network 21. Note that other terminal devices 10 other than the terminal device 10 whose packet loss count is d or more or whose radio field intensity is weaker than f are still communicating with the information processing apparatus 30 via the IP network 21. Sending and receiving data.

  The switching control unit 15 determines whether or not the number of lost packets is “d” or more by the packet loss rate calculation unit 151 and determines whether or not the field strength is lower than “f” by the field strength detection unit 152. ing. These determination results are output to the return control unit 153. Then, after the communication data transmission path is switched to the public telephone network 22, that is, following step S5, the switching control unit 15 causes the return control unit 153 to reduce the number of lost packets to less than “d” and It is determined whether the intensity is “f” or more (step S6).

  When the packet loss number is smaller than “d” and the radio wave intensity is “f” or more (step S6: Yes), the switching control unit 15 causes the return control unit 153 to output communication data to the IP network 21. A control signal Q for control is output to the input / output switching unit 13 (step S7). As a result, the input / output switching unit 13 transmits communication data to the information processing apparatus 30 via the IP network 21.

Subsequently, the switching control unit 15 uses the return control unit 153 to calculate the t-test statistic t represented by the equation (1) by using the t distribution table as a statistic t ₀ (m + n−2, α). It is determined whether it is smaller than (step S8). When t is smaller than t ₀ (t <t ₀ ) (step S8: Yes), the switching control unit 15 uses the return control unit 153 to disconnect the public telephone network 22 so that the connection is disconnected. The control signal is output to the input / output switching unit 13. Thereby, the input / output switching unit 13 disconnects the connection of the public telephone network 22 (step S9).

On the other hand, when t is t ₀ or more (t ≧ t ₀ ) (step S8: No), the switching control unit 15 controls the return control unit 153 to control to output communication data to the public telephone network 22. The signal P is output to the input / output switching unit 13 (step S5). As a result, the input / output switching unit 13 transmits communication data to the information processing device 30 via the public telephone network 22. In addition, the IP processing unit 14 transmits an empty packet to the information processing apparatus 30 via the IP network 21.
In the operation of the switching control unit 15 described above, the processes in steps S10 to S13 may be executed with priority over the processes in steps S1 to S4.

  According to the communication system 1 of the first embodiment, it is determined whether or not a failure has occurred in the terminal 10 using the packet loss rate received via the IP network 21 or the radio wave intensity from the access point 23. By switching the transmission path to the IP network 21 or the public telephone network 22 based on the determination result, it is possible to realize a high-quality multi-party call at a low cost. In addition, since the wireless LAN is formed by the plurality of terminals 10 and the access point 23, the terminal 10 using the IP network 21 does not need a wireless license like a commercial wireless income device, and can easily be used. Can be added. Accordingly, such a terminal 10 is suitable for performing a broadcasting operation by a plurality of staff at a disaster occurrence site or an outdoor event site, for example.

(Second Embodiment)
[Communication system configuration]
Next, a communication system according to the second embodiment will be described with reference to FIG. FIG. 6 is a configuration diagram of a communication system according to the second embodiment. As shown in FIG. 6, this communication system 1 </ b> A is shown in FIG. 1 except that it includes two transmission apparatuses 50 (50 </ b> A, 50 </ b> B) and an access point 23 a connected to the transmission apparatus 50 (50 </ b> A). The configuration is the same as the communication system 1 shown. Therefore, the same components as those in FIG.

A communication system 1A according to the second embodiment connects a plurality of terminals 10 and an information processing device 30 via a geostationary satellite line and a transmission line 20, and a transmission device (first device) is connected to the terminal 10 side. Transmission apparatus) 50 </ b> A and an access point 23 a, and a transmission apparatus (second transmission apparatus) 50 </ b> B connected to the access point 23 of the transmission path 20.
The transmission device 50 transmits data between either the terminal 10 or the transmission path 20 and the geostationary satellite 60, and includes a packet demultiplexing unit 51, a modem unit 52, and a transmission / reception unit 53. .

The packet demultiplexing unit 51 multiplexes packets input from the outside of the transmission device 50 into one data string and outputs the multiplexed data to the modem unit 52. The packet demultiplexing unit 51 decomposes the multiplexed data input from the modem unit 52 and outputs it to the access point 23.
The modem unit 52 modulates the data sequence multiplexed by the packet demultiplexing unit 51 and outputs the modulated data sequence to the transmission / reception unit 53. The modem unit 52 demodulates the data sequence output from the transmission / reception unit 53 and outputs the demodulated data sequence to the packet demultiplexing unit 51.

The transmission / reception unit 53 transmits the modulated data sequence output from the modulation / demodulation unit 52 to the geostationary satellite 60. The transmission / reception unit 53 receives a data string transmitted from the geostationary satellite 60 and outputs the data sequence to the modem unit 52. Each of the above-described units 51 to 53 may form a unit, may be divided into units for each function, or the transmission apparatus 50 may form one unit. .
The geostationary satellite (geostationary satellite line) 60 is, for example, Super Bird (registered trademark), JCSAT, ASIASAT, or the like.

[Operation of communication system]
Next, the operation of the communication system 1A according to the second embodiment will be described. The operation of the communication system 1A according to the second embodiment is the same as that of the first embodiment except that the connection line between the terminal 10 and the IP network 21 is different. That is, when the terminal 10 and the IP network 21 are connected, the terminal 10 has an access point 23a, a transmission device 50A, a geostationary satellite 60, and a transmission device arranged in the vicinity of the terminal 10. 50B and the access point 23 are connected to the IP network 21. The terminal 10 and the access point 23a form a wireless LAN, and the plurality of terminals 10 form a group as a whole.

  In this case, packets transmitted from a plurality of terminals 10 toward the information processing device 30 are wirelessly transmitted to the access point 23a, and the packet demultiplexing unit 51 of the transmission device 50A connected to the access point 23a 1 Multiplexed into one data string. Then, in the transmission device 50 </ b> A, the data sequence is modulated by the modulation / demodulation unit 52 and transmitted to the geostationary satellite 60 by the transmission / reception unit 53. Then, the geostationary satellite 60 transmits the data string transmitted from the transmission device 50A to the transmission device 50B. The transmission device 50B demodulates the data sequence received by the transmission / reception unit 53 by the modulation / demodulation unit 52, decomposes it into packets by the packet demultiplexing unit 51, and outputs the packet to the access point 23. This packet is transmitted to the information processing apparatus 30 via the IP network 21. Then, the multiplexed audio signal added by (N−1) by the information processing device 30 is transmitted downstream to the plurality of terminals 10 through the opposite path in the same manner as in the upstream.

  According to the communication system 1A of the second embodiment, the access point 23a can be connected to the transmission device 50A, and can be connected to the transmission device 50B and the IP network 21 via the geostationary satellite 60. Therefore, not only the same effect as the first embodiment is obtained, but also, for example, when the communication system 1A is used for broadcasting work, the public telephone network 22 cannot be used at a relay site using a plurality of terminals 10. In the case of an environment, an access point 23a is installed in an on-site relay vehicle or the like, and is connected to a broadcasting center in which the information processing apparatus 30 is installed via a geostationary satellite 60, thereby allowing a plurality of terminals 10 on the site to Multi-party calls can be made at low cost. Also, when a disaster occurs, congestion may occur in the line due to communication restrictions of the public telephone network 22, and in such a case as well, by installing the access point 23a on the field relay vehicle etc., It enables multi-party calls through satellite lines and secures on-site support means in emergency broadcast operations.

  The first and second embodiments have been described above, but the present invention is not limited to this, and can be implemented in various ways without changing the gist thereof. For example, in the first and second embodiments, it has been described that a plurality of terminals 10 form a wireless LAN for one access point 23 (23a). However, the present invention is not limited to this. The terminal 10 may form a wireless LAN with different access points. In this case, for example, in broadcasting business, not only a plurality of terminals 10 are used for relatively short distance communication such as a studio and a sub-adjustment room, but also the terminal 10 used in the sub-adjustment room and the relay site It can be expanded to multi-party calls made with local stations or terminals 10 used overseas. As a result, it is possible to broaden the range of communication related to broadcasting technology and coordination of program production.

  In the first and second embodiments, the terminal 10 is in the best mode in which the switching control unit 15 includes both the packet loss rate calculation unit 151 and the radio wave intensity detection unit 152. However, only one of them is selected. You may make it prepare. For example, when the switching control unit 15 includes only the packet loss rate calculation unit 151, a wired LAN that directly connects each terminal 10 to the IP network 21 using a cable is used. Further, in the operation of the switching control unit 15 shown in the flowchart of FIG. 5, Steps S10 to S13 are omitted, and the process of Step S6 is replaced with a process of determining whether the number of lost packets is smaller than d. When a wired LAN is used in this way, the configuration of the terminal 10 can be simplified and the manufacturing cost can be reduced.

  If the switching control unit 15 includes only the radio wave intensity detection unit 152 using a wireless LAN, Steps S1 to S4 are omitted and Step S6 is performed in the operation of the switching control unit 15 shown in the flowchart of FIG. This process is replaced with a process for determining whether the radio field intensity is f or more. In this case, when the radio field intensity becomes weak, the packet loss rate also decreases, so that the same effect as in the first embodiment can be obtained.

It is a lineblock diagram of the contact system of a 1st embodiment. It is a block diagram which shows the structure of a terminal. It is an external view of an example of a terminal. It is a block diagram which shows the structure of information processing apparatus. It is a flowchart which shows operation | movement of the switching control part of a terminal. It is a block diagram of the communication system of 2nd Embodiment.

Explanation of symbols

1, 1A Contact system 10 Terminal 11 Interface unit 12 Audio processing unit 13 Input / output switching unit (transmission path switching means)
14 IP processing unit 15 switching control unit (transmission path switching control means)
151 Packet loss rate calculation unit (packet loss rate calculation means)
152 Radio wave intensity detector (Radio wave intensity detector)
153 Return control unit (return control means)
16 Information processing section (number switching means)
17 Storage unit (storage means)
DESCRIPTION OF SYMBOLS 20 Transmission path 21 IP network 22 Public telephone network 23 Access point 30 Information processing apparatus 31 Data conversion part 32 Decoding part 33 Mixing part (multiplexing means)
34 Encoding unit 35 Packet conversion unit 36 Reception unit 37 Transmission unit 40 Main unit 41 Microphone 42 Speaker 43 Operation buttons (operation means)
DESCRIPTION OF SYMBOLS 50 Transmission apparatus 51 Packet demultiplexing part 52 Modulation / demodulation part 53 Transmission / reception part 60 Geostationary satellite

Claims (6)

By connecting via the IP network or the public telephone network to the multiplexing means that multiplexes communication data transmitted from other than the predetermined transmission source and returns the data to the predetermined transmission source. A terminal that transmits / receives communication data to / from a terminal,
Transmission path switching means for switching between the IP network and the public telephone network as the communication data transmission path;
Based on at least the packet loss rate among the loss rate of packets received via the IP network and the radio wave intensity received from the access point connected to the IP network, the communication data transmission path is routed to the IP network. Transmission path switching control means for controlling the transmission path switching means to switch from the public telephone network to the public telephone network;
With
The transmission path switching control means is
If the loss rate of packets received via the IP network is greater than a first predetermined value, a control signal for dial-up connection to the multiplexing means via the public telephone network is switched to the transmission path. And when the loss rate of packets received via the IP network is larger than the first predetermined value after the call of the public telephone network is established, the communication data is sent to the public telephone network. A terminal comprising: a packet loss rate calculating means for outputting a first switching control signal for output to the transmission path switching means. By connecting via the IP network or the public telephone network to the multiplexing means that multiplexes communication data transmitted from other than the predetermined transmission source and returns the data to the predetermined transmission source. A terminal that transmits / receives communication data to / from a terminal,
Transmission path switching means for switching between the IP network and the public telephone network as the communication data transmission path;
Based on at least the radio wave intensity of the loss rate of packets received via the IP network and the radio wave intensity received from an access point connected to the IP network, the communication data transmission path is routed from the IP network to the IP network. Transmission path switching control means for controlling the transmission path switching means to switch to a public telephone network;
With
The transmission path switching control means is
When the intensity of the radio wave received from the access point becomes smaller than a predetermined second predetermined value, a control signal for dial-up connection to the multiplexing means via the public telephone network is transmitted to the transmission path And when the duration of the state in which the radio wave intensity received from the access point is smaller than the second predetermined value exceeds a predetermined time after the call of the public telephone network is established, the communication data A terminal comprising: radio field intensity detecting means for outputting a first switching control signal for outputting the signal to the public telephone network to the transmission line switching means. The transmission path switching control means is
After the first switching control signal is output to the transmission path switching means, if the loss rate of packets received via the IP network is not more than the first predetermined value, the communication data is transferred to the IP network. The terminal according to claim 1 , further comprising a return control unit that outputs a second switching control signal to be output to the transmission path switching unit. The transmission path switching control means is
After the first switching control signal is output to the transmission path switching means, if the intensity of the radio wave received from the access point is equal to or higher than the second predetermined value, the communication data is output to the IP network. The terminal according to claim 2 , further comprising a return control means for outputting a second switching control signal for output to the transmission path switching means. The return control means is configured to calculate an average value of the number of lost packets in m sets of packet groups including a predetermined number of packets before the loss rate of packets received via the IP network is greater than the first predetermined value. m ₀ , unbiased variance is σ ₀ ² , and the average value of the number of lost packets in the n sets of packets composed of the predetermined number of packets after the loss rate is greater than the first predetermined value Is the statistical value of the t-test shown in equation (1), where m _e is the unbiased variance is σ _e ^2, and the value in the t distribution table when α is the significance level is t ₀ (m + n−2, α). Are each calculated as t,

4. The terminal according to claim 3 , wherein when t <t ₀ , a disconnection control signal for disconnecting the connection of the public telephone network is output to the transmission path switching means. Said return control means of claim in the case of t ≧ t _0, and outputs a first switching control signal for outputting the communication data to the public telephone network to the transmission path switching means 5 The terminal described in 1.

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