JP4591363B2 - Satellite communication system and satellite communication earth station - Google Patents

Description

  The present invention relates to a satellite communication system and a satellite communication earth station that perform communication including VoIP (Voice over Internet Protocol) data in satellite communication in which line assignment is performed by demand assignment multiple access (DAMA: Demand Assignment Multiple Access). .

  For example, Non-Patent Document 1 discloses a conventional technique for performing BOD (Bandwidth On Demand) control in a satellite communication system that performs satellite communication line control by DAMA. According to this prior art, the communication speed between the earth stations to which the satellite communication lines are assigned by the DAMA control can be changed in ten or more stages. Specifically, the amount of traffic is monitored by a data transmission adapter provided in the earth station, and a request for changing the transmission rate according to the amount of traffic is transmitted to the DAMA control station. In response to this change request, the DAMA control station sets a line, transmits a line control signal to the earth station, and the received earth station sets a frequency channel and a transmission rate according to the line control signal.

"Development of IP communication satellite communication system" Toru Kikuta, 2004 Proceedings of the IEICE General Conference B-3-2, P.I. 330, March 22, 2004

  According to the conventional technique described in Non-Patent Document 1, when VoIP communication and other application communication are mixed, BOD control is performed by increasing / decreasing the amount of other application data, and line disconnection frequently occurs. As a result, there is a problem that transmission delay occurs in VoIP data transmission and transmission efficiency deteriorates. Further, if there is no BOD (Bandwidth On Demand) control, the bandwidth of the communication line is fixed regardless of the increase or decrease in the amount of data in the application, so that the bandwidth can be allocated more flexibly to increase the frequency utilization efficiency. There was a problem that it was impossible.

  The present invention has been made to solve the above-described problems. In satellite communication including VoIP communication and other application communication, a satellite that performs communication using the BOD control function without impairing the transmission efficiency of VoIP communication. An object is to obtain a communication system and a satellite communication earth station.

A satellite communication system according to a first aspect of the present invention is a satellite communication system that performs communication by performing line assignment at a satellite communication center station in response to a line assignment request from a satellite communication earth station. The above other applications occupying the total amount of data transmitted by adding the BOD request signal generating unit for generating the BOD request signal for requesting the bandwidth change of the communication line to the satellite communication center, and the amount of VoIP data and other applications. A data amount determination processing unit for selecting communication in a fixed band if the ratio of the data amount exceeds a predetermined threshold value .

Satellite earth station according to the invention of claim 2 is the satellite earth station communicating with the line allocation request of the communication line to the satellite communication center station, generates a BOD request signal for requesting bandwidth change of the communication line Fixed if the ratio of the data amount of the other application in the total amount of data transmitted by adding the BOD request signal generation unit, the VoIP data amount and the data amount of the other application exceeds a predetermined threshold And a data amount determination processing unit for selecting communication in a band.

According to this invention, the satellite communication earth station requests all the data to be transmitted by requesting the bandwidth change of the communication line by the BOD request signal generation unit and adding the VoIP data amount and the data amount of other applications by the data amount determination unit. If the ratio of the data volume of the other application in the volume exceeds the predetermined threshold , communication in the fixed band is selected. Therefore, if the data volume of the other application increases, the communication shifts to the fixed band. At that time, no BOD request is generated, the number of line disconnections due to BOD control is reduced, and the transmission efficiency of VoIP communication can be improved.

Embodiment 1

  A satellite communication earth station according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a satellite communication earth station according to Embodiment 1 of the present invention, and FIG. 2 is a functional block diagram showing a configuration of a satellite GW in the satellite communication earth station. In FIG. 1, 1 is an antenna unit that transmits and receives radio waves to and from a communication satellite, and 2 is a low-noise amplification and low-frequency conversion of a received signal, and a high-frequency conversion and high-output amplification of a transmission signal. It is a transmission / reception unit. Reference numeral 3 denotes a modem unit that demodulates a reception signal and modulates a transmission signal. Reference numeral 4 denotes a satellite GW (satellite gateway) that transfers IP data between various IP devices and the modem unit 3 and controls data communication. . The satellite communication earth station mainly includes these antenna unit 1, transmission / reception unit 2, modem unit 3, and satellite GW4. This satellite communication earth station is connected to IP telephone 5 and IP terminal 6 which are various IP devices via a network, and communicates communication data (voice data and information data) transmitted and received by IP telephone 5 and IP terminal 6. It transmits / receives to / from other satellite communication earth stations or satellite communication center stations via satellites.

  The satellite GW4 will be described with reference to FIG. Reference numeral 7 denotes a LAN interface unit serving as an interface for communication with the IP phone 5 or the IP terminal 6 via the network. The VoIP data from the IP phone 5 and application data other than VoIP from the IP terminal 6 (for example, TCP / IP Data, FTP data, stream data, etc., hereinafter referred to as “other application data”). A format conversion unit 8 converts the format of the imported VoIP data or other application data into a data format based on a communication protocol suitable for satellite communication. However, in the case of a satellite communication system that performs communication in the IP data format from the terminal in satellite communication, the format conversion unit 8 does not need to perform format conversion. Reference numeral 9 denotes a VoIP data amount detection unit that detects the amount of VoIP data captured by the LAN interface unit 7, and reference numeral 10 denotes another application data amount detection unit that detects the data amount of other application data captured by the LAN interface unit 7. is there. 11 compares the amount of VoIP data detected by the VoIP data amount detection unit 9 and the amount of other application data detected by the other application data amount detection unit 10 with a predetermined threshold value. A data amount determination processing unit for determining whether or not the following is satisfied, and 12 performs a speed increase / decrease request to the satellite communication line by increasing / decreasing the IP data amount, and the data amount of the IP telephone 5 and the IP terminal 6 and the satellite line data A BOD request signal generation unit that performs matching control with the speed, and 13 fixes the amount of data transmitted / received to the satellite line regardless of fluctuations in the data quantity from the IP telephone 5 and the IP terminal 6 (constant satellite line data rate). ), A fixed band request signal generation unit for setting allocation of data amounts of the IP telephone 5 and the IP terminal 6, and 14 is an acceleration or deceleration request from the BOD request signal generation unit 12, and a fixed band The fixed bandwidth request from the request signal generator section 13 is a request signal transmitting circuit for transmitting the DAMA system satellite communications center station.

  Next, data amount determination processing in the data amount determination processing unit 11 will be described with reference to FIG. In FIG. 3, it is assumed that the satellite communication earth station performs communication in the BOD mode as a default in step S1. As described above, the communication in the mode with BOD controls the increase / decrease of the satellite communication speed according to the communication data in the satellite earth station, and the effective use of the frequency band is achieved. The amount of VoIP data from the IP phone 5 is input to the data amount determination processing unit 11 in step S2 and the amount of other application data from the IP terminal 6 is input to step S3. These data amounts are detected by the VoIP data amount detection unit 9 and the other application data amount detection unit 10. In step S4, the BOD request signal generating unit 12 generates a request for increasing or decreasing the satellite communication speed based on the change in the data amount and transmits it to the satellite communication center station. , Variably control the communication band to the satellite communication earth station. FIG. 4 is a schematic diagram for explaining line allocation in the satellite communication center station in response to a BOD request from the satellite communication earth station. Since the satellite communication earth station is assigned the communication band 15, when the satellite communication earth station transmits a speed increase request by BOD control, the satellite communication center station that has received the request transmits the communication band in the DAMA device in the station. A communication band 16 wider than 15 is reassigned.

  In FIG. 3, a threshold determination process based on the VoIP data amount and the other application data amount is performed in step S5. The data amount determination processing unit 11 calculates the ratio of the other application data amount to the total amount of data to be transmitted (the sum of the VoIP data amount and the other application data amount), and the ratio of the other application data amount is a predetermined threshold. It is determined whether the value is exceeded. If the threshold value is not exceeded, the mode with BOD is continued. That is, the process returns to step S1. The data amount determination processing unit 11 calculates the ratio of the amount of other application data to the total amount of data to be transmitted (the amount obtained by adding the amount of VoIP data and the amount of other application data). It is determined whether or not the amount ratio exceeds a predetermined threshold value.

  In step S6, the fixed band request signal generator 13 generates a fixed band request and transmits the request from the request signal transmission circuit 14 to the satellite communication center station. In the DAMA device of the satellite communication center station, the satellite communication earth station is set in the BOD-free mode. Set to. In step S7, the other application data amount is monitored, and if the data amount decreases, the determination in step S8 is performed. If the other application data amount is compared with a predetermined threshold value in step S8 and exceeds the threshold value, the BOD no mode is continued in step S6, and if the threshold value is not exceeded, step is continued. The process proceeds to S1 and returns to the mode with BOD.

  By performing the above processing, in a situation where the amount of VoIP data is small and the amount of other application data is increasing, the speed is first increased by BOD control. For example, the speed is increased stepwise. It is possible to perform the change step by one step. When the amount of other application data increases and exceeds a predetermined threshold value, the communication shifts to fixed band communication. At that time, no BOD request is generated, the number of line disconnection by BOD control is reduced, and the transmission efficiency of VoIP communication is improved. can do. Conversely, when the amount of VoIP data is large and the amount of other application data is small, the speed of frequency increase by BOD control is small, so that the transmission efficiency of VoIP communication is not affected by other applications. When fixed band communication is always performed, even when communication by other applications is not performed, the band is fixedly allocated and the use efficiency of the satellite communication line deteriorates. By switching between the mode with BOD and the mode without BOD through simple processing, it is possible to increase the utilization efficiency of the satellite communication line.

It is a block diagram of the satellite communication earth station which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows the structure of the satellite GW in a satellite communication earth station. It is a processing flow which shows the determination process of the data amount in the data amount determination process part of the satellite GW. It is a schematic diagram explaining the line allocation in the satellite communication center station with respect to the BOD request | requirement from a satellite communication earth station.

Explanation of symbols

4 Satellite GW
9 VoIP data amount detection unit 10 Other application data amount detection unit 11 Data amount determination processing unit 12 BOD request signal generation unit 13 Fixed band request signal generation unit 14 Request signal transmission circuit

Claims (2)

In a satellite communication system that performs communication by allocating a line at the satellite communication center station in response to a line allocation request from the satellite communication earth station, the satellite communication earth station requests the satellite communication center to change the band of the communication line. The ratio of the data amount of the other application occupying the total data amount transmitted by adding the BOD request signal generation unit that generates the BOD request signal and the VoIP data amount and the data amount of the other application has a predetermined threshold value. A satellite communication system comprising: a data amount determination processing unit that selects communication in a fixed band if exceeding . In the satellite earth station communicating with the line allocation request of the communication line to the satellite communication center station, and the BOD request signal generator for generating a BOD request signal for requesting bandwidth change of the communication line, VoIP data amount and other A data amount determination processing unit for selecting communication in a fixed band if the ratio of the data amount of the other application in the total data amount to be transmitted that is added to the data amount of the application exceeds a predetermined threshold ; A satellite communication earth station characterized by comprising:

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