JP3050308B2 - DAMA satellite communication system, master station used therefor, and frequency allocation control method therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a frequency management method in a satellite communication system, and more particularly to a frequency allocation control method in a DAMA satellite communication system accommodating communications at different information transmission rates.

[0002]

2. Description of the Related Art As one of multiple access satellite communication systems for communicating voice and data between earth stations via satellites, frequency multiple access (FDM) in which a frequency is assigned to each communication line.
A: Frequency Division Multiple Access) system. Among the FDMA systems, the SCPC (Single Channel Per Carrier) system is suitable for a satellite communication system composed of a large number of earth stations having a relatively small communication capacity. In the SCPC system, one carrier is allocated to one voice and data line, and thus the allocation is very flexible.

[0003] Also, when classifying based on frequency allocation,
Pre-assigned multiple access (PAMA:
Pre Assignment Multiple Access (Demand Assignment Multip) and Demand Assignment Multip
le Access) method. In the PAMA system, since the frequency is fixedly allocated, the line is put on hold even during communication, and the line use efficiency is poor, and the number of earth stations accommodated is limited. For this reason, a DAMA that allocates a frequency only when a communication request is issued
In many cases, the system is adopted.

FIG. 5 shows a configuration of a general DAMA satellite communication system. In the DAMA satellite communication system, the control of satellite line allocation is performed only by the slave station.
Although there is a configuration without a master station, a configuration in which central control is performed by the master station is shown here. That is, as shown in the figure, the DAMA satellite communication system includes a master station C that manages the assignment of satellite channels and the connection status of each slave station, and first to n-th slave stations R1 to Rn (n Is an integer of 2 or more) and a satellite S as a relay station.

[0005] A slave station having generated a communication request exchanges connection control information through a common control channel called CSC. Now, it is assumed that a communication request to the qth slave station Rq (1 ≦ q ≦ n and q ≠ p) has occurred at the pth slave station Rp (1 ≦ p ≦ n). In this case, the requesting p-th slave station Rp notifies the q-th slave station Rq of the connection destination and the band required for transmission to the master station C via the satellite S via the common control channel.

In response to the connection request, the master station C checks whether or not the q-th slave station Rq of the connection destination is in a communicable state. Then, the satellite band is notified to the p-th slave station Rp of the request source and the q-th slave station Rq of the connection destination via the satellite S using the downlink common control channel. Thereby, the p-th slave station Rp that has made the connection request and the q-th
Rq communicates by SCPC using the frequency allocated via the satellite S. Thereafter, each of the slave stations that have completed the communication transmits a disconnection notification to the master station C.

[0007] When the master station C receives the disconnection notification, the allocated frequency is released.

Incidentally, various prior arts which are considered to be related to the present invention are also known. For example, JP-A-63-15575
Japanese Patent Publication No. 6 (hereinafter, referred to as a first prior art) describes a "demand assign multiple access communication system" that can improve line use efficiency regardless of the form of information to be transmitted. In the demand assignment multiple access communication system described in the first prior art, a channel for packet communication is allocated by a master station, and the allocated channel for packet communication is shared by a plurality of slave stations performing packet communication. ing.

Japanese Patent Laid-Open Publication No. 1-284027 (hereinafter referred to as a second prior art) discloses a "DAM" in which a line is allocated equally with a reduced time from the generation of a call to the start of communication.
A communication method "is described. In the second prior art, all the slave stations have a function of monitoring the line status and assigning a line. Thus, when a call is generated, each slave station allocates a free line and starts a call, and the call cancels the allocation by itself.

Further, Japanese Patent Laid-Open Publication No. Hei 8-23297 (hereinafter referred to as a third prior art) discloses a circuit for satisfying a preset service condition for each of various communication requests having different transmission speeds. A "line allocation control method" is disclosed, which aims to improve line use efficiency. That is, in the third prior art, when allocating a line to each of various communication requests such as a low-speed call, a medium-speed call, and a high-speed call, the communication request status in the future is determined based on the past communication request and service quality. And predict service quality. Then, in order to satisfy a preset service condition, a line allocation search start position, an empty line search method, and traffic regulation as line allocation control parameters are dynamically changed. As a result, the line use efficiency within a certain frequency band can be improved.

[0011]

As described above, in the conventional DAMA satellite communication system, the use time of the channel by the communication between the slave stations is not constant, so that the use is completed and released between the allocated frequencies. Band may occur. If the information transmission speed and the related parameters in each communication are the same, the frequency band allocated to the slave station is the same as shown in FIG. 6, and the reassignment of the released frequency band is easy.

However, in a system in which child station groups handling voice and data coexist, the transmission speed differs for each group, and in that case, the bandwidth required for transmission differs as shown in FIG. In FIG. 7, a frequency band indicated by an uppercase F (subscript) indicates a wide frequency band, and a frequency band indicated by a lowercase f (subscript) indicates a narrow frequency band. For this reason, for example, even if a narrow frequency band of f2 is released, a band of Fn requiring a wider frequency band cannot be allocated. If this occurs frequently, stable provision of communication services that require a wide frequency band cannot be guaranteed. In other words, when one frequency resource is shared by calls of different communication services, that is, calls requiring different frequency bandwidths (multiple traffic), the call loss rate of a call having a large required frequency bandwidth is reduced by the required frequency bandwidth. The call loss rate for a call having a small bandwidth becomes remarkably large. Such an effect,
In this technical field, it is referred to as "outgoing fraction effect".

[0013] Accordingly, it is an object of the present invention to provide a DAMA satellite communication system and a frequency allocation control method for the same, which can suppress the above described outgoing line fraction effect.

Another object of the present invention is to provide a DAMA satellite communication system capable of stably operating each communication service even when traffic in the system fluctuates, and a method of controlling frequency allocation thereof.

The first to third prior arts do not disclose any specific means for achieving the above object.

That is, in the conventional DAMA communication system, the master station allocates the frequency itself as a line, occupies it, and the slave station communicates.
One prior art discloses a technical idea in which an assigned frequency is shared by a plurality of slave stations and communication is performed by a slot Aloha method so as to effectively use the frequency. In other words, this first prior art corresponds to a communication scheme from a slave station to a master station of a CSC line in which the master station requests a call connection to the slave station, which is used in a conventional DAMA system. The present invention does not intend to provide a communication system using the CSC line.

In the second prior art, when a slave station acquires a line, the slave station monitors frequency usage information broadcast from the master station and acquires the line by itself, thereby shortening the line acquisition time. It merely discloses the technical idea described above, and the frequency allocation itself is completely different from the present invention performed by the master station.

Further, the third prior art discloses that when the communication speeds of the slave stations are different in the system, depending on the required bandwidth,
A technical idea that stabilizes each communication service and effectively uses a frequency by discriminating a start position of acquisition of a used frequency and changing the position according to a service condition and an intra-system traffic state is disclosed. This third prior art is most relevant to the present invention and is considered to be effective in preventing the "outgoing line fraction effect" to be solved by the present invention. However, the third prior art is:
The method of statistically calculating the usage state and the method of determining the frequency acquisition start position disclosed therein are ambiguous, and are described using specific examples, but are complicated.

On the other hand, in the present invention, each communication service is stabilized and the frequency is effectively used by making a frequency band reservation according to the service condition and the traffic state. That is, the present invention employs a bandwidth reservation not present in the third prior art, discloses a specific bandwidth reservation / release method and a traffic information acquisition method, and proposes a highly feasible system. It is.

[0020]

The present invention employs the following technical structure to achieve the above object. That is, according to the first aspect of the present invention, any one of a plurality of slave stations sends a communication request to another slave station to a master station via a satellite through a common control channel (CSC: Common Signa).
lling Channel), and the master station should allocate a necessary band based on the communication request and use the common control channel to use the communication request source slave station and the communication connection destination slave station. By instructing a band, in a DAMA satellite communication system in which the slave station of the communication request source and the slave station of the communication connection destination can perform voice and data communication via the satellite, the master station includes: When the number of used lines is acquired for each service type, the statistical information storage unit that calculates the frequency usage rate, and the frequency usage standard for each service type is held, and when a notification of connection failure related to a specific service type is received. Then, the latest frequency usage rate for the specific service type is obtained from the statistical information storage unit, and when a predetermined condition is satisfied, it is possible to use only the specific service type. A DAMA satellite communication system having a reservation control unit for reserving a certain frequency band is obtained.

According to the second aspect of the present invention, any one of the plurality of slave stations sends a communication request to another slave station to the master station via a satellite using a common control channel. Notify, the master station allocates a necessary band based on the communication request, and indicates the band to be used for each of the communication request source slave station and the communication connection destination slave station using the common control channel. In a DAMA satellite communication system in which the communication requesting slave station and the communication connection destination slave station can perform voice or data communication via the satellite, the master station determines the number of call connection requests by a service type. A statistical information storage unit that separately calculates and calculates the call connection request rate per unit time, obtains the number of lines used for each service type, and calculates the frequency usage rate, and calculates the frequency usage rate for each service type. Keep the standards Receiving a notification of connection failure relating to a specific service type, acquiring a recent frequency usage rate for the specific service type from the statistical information storage unit, and when a predetermined condition is satisfied, A predetermined frequency band is reserved so that it can be used only by the service type, and the call connection request rate is periodically acquired from the statistical information storage unit for the specific service type for which the reservation has been made, and this acquired A reservation control unit for releasing the reserved predetermined frequency band when the call connection request rate becomes lower than the predetermined rate.
An AMA satellite communication system is obtained.

Further, according to the third aspect of the present invention, any one of the plurality of slave stations sends a communication request to another slave station to the master station via a satellite using the common control channel. Notify, the master station allocates a necessary band based on the communication request, and indicates the band to be used for each of the communication request source slave station and the communication connection destination slave station using the common control channel. A DAMA satellite communication system in which the slave station of the communication request source and the slave station of the communication connection destination can perform voice and data communication via the satellite, a frequency allocation control method at the master station, A frequency allocation control method for a DAMA satellite communication system, characterized in that a frequency band is reserved according to service conditions and traffic conditions.

[0023]

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

FIG. 5 shows a demand assignment multiple access (DAM)
A: Demand Assignment Multiple Access (A) shows a general configuration of a satellite communication system. As shown in the figure, the DAMA satellite communication system has a master station C that manages the assignment of satellite lines and the line connection of each slave station, and a first station.
And a satellite S as a relay station. The slave station requests a line connection using a common control channel (CSC), and the master station C responds to the line ( The sub-stations communicate with each other by allocating a frequency.

In FIG. 5, a thick solid line indicates a slave station communication line, a thick broken line indicates an inbound CSC line, and a thin broken line indicates an outbound CSC line.

FIG. 1 is a block diagram showing an embodiment of a master station C according to the present invention. As shown in FIG. 1, the master station C includes a transmitting / receiving unit 11, a CSC frame processing unit 12,
It is composed of a communication line control unit 13, a statistical information storage unit 14, and a reservation control unit 15.

The transmission / reception unit 11 is a transmission / reception unit for a common control channel. When any one of the slave stations starts communication with any one of the slave stations, the transmission / reception unit 11 sends a message of a line assignment request to the satellite S. Will be sent via From the master station C, the communication request message is asynchronously notified from the plurality of slave stations R1 to Rn.

The statistical information storage unit 14 periodically classifies the number of call connection requests asynchronously sent from the communication line control unit 13 according to the frequency bandwidth and type required for the communication line (this is referred to as a service type). A) to calculate the amount per unit time (call connection request rate). The statistical information storage unit 14
Further, it obtains the number of used lines for each service type from the communication line control unit 13 and calculates each frequency usage rate.

The reservation control unit 15 holds a frequency usage standard for each service type, which is input from an operator through a monitoring control device (not shown). Reservation control unit 15
Also, upon receiving from the communication line control unit 13 a notification of call connection failure due to insufficient frequency, the latest frequency usage rate for the service type is acquired from the statistical information storage unit 14 and Then, the larger of the proportions of the bands reserved for is compared with the frequency usage standard, and it is determined whether the service state at that time is appropriate for the corresponding service type. If the frequency band is not appropriate, the reservation control unit 15 reserves a frequency band corresponding to the difference between the frequency usage rate reference and the above comparison so that it can be used only by the service type, and the reserved band can be used only by the service type thereafter. Thereafter, the reservation control unit 15
Periodically obtains the number of call connection requests from the statistical information storage unit 14 for the service type for which the reservation has been made, and releases the reserved band when it is determined that the number of call connection requests is not required due to a decrease in the number of call connection requests.

Therefore, the outgoing line fractional effect occurs in that the frequency is occupied by a call having a small required bandwidth, and a fractional vacancy occurs in the frequency band so that a call requiring a large bandwidth cannot be allocated. It is possible to prevent the line connection of a call having a large required bandwidth from being continuously hindered, and to stably operate each communication service even with traffic fluctuation in the system.

The communication line control unit 13 manages information required for the slave station to communicate, such as routing information and frequency information to be assigned, and the status of the slave station.
It processes a call connection request including a service type, a destination address, and the like from a slave station received from the C frame processing unit 12, and determines a slave station to connect to. Then, the communication line control unit 13
Transmits a communication start request and information to allocate a frequency to the satellite S through the CSC frame processing unit 12 and the transmission / reception unit 11. The communication line control unit 13 also notifies the statistical information storage unit 14 of the information of the call connection process with the reason added thereto, and periodically updates the number of lines currently held for each service type from the statistical information storage unit 14. Notify on demand.

FIG. 2 shows a method of allocating a frequency band in the communication line control unit 13. In FIG. 2, the horizontal axis is frequency f, and the frequency band indicated by F is a frequency band that can be used in the present DAMA satellite communication system.

As shown in FIG. 2, the communication line control unit 13
Determines the frequency band to be allocated as follows.
That is, the reservation control unit 15
If there is a band reserved from
No. 3 searches and determines an area where a band equal to or more than the bandwidth required by the line is vacant from the higher frequency band of the band.

On the other hand, if there is no vacant band in the reserved band or there is no reserved band itself, the communication line control unit 13
From the top of the frequency band F, an area where a band equal to or more than the bandwidth required by the line is vacant is searched for and determined.

The statistical information storage unit 14 is a communication line control unit 13
The number of call connection requests per unit time and the frequency usage rate are calculated based on the notification of the call connection and the number of lines from the server, and are held for each service type. Here, the frequency usage rate is calculated from the frequency bandwidth used for one line and the traffic volume of the service type. That is, assuming that the usage rate of this frequency is Pfreq, the traffic volume is a, the bandwidth used for one line is B, and the total frequency bandwidth is Bt, the usage rate Pfreq
Is calculated by the following equation (1).

[0036]

(Equation 1) The traffic volume a for each service type can be calculated from the information stored in the statistical information storage unit 14. That is, assuming that the period at which the statistical information storage unit 14 obtains the number of lines from the communication line control unit 13 is t, the number of lines at that time is Ci, and the time interval at which the statistical information storage unit 14 integrates is T, The traffic volume a is represented by the following Equation 2.

[0037]

(Equation 2) The reservation control unit 15 holds the frequency usage standard for each service type input from the operator through the monitoring control device. Upon receiving a notification from the communication line control unit 13 that a call connection has failed due to insufficient frequency, the reservation control unit 15 first obtains the frequency usage rate for the service type from the statistical information storage unit 14. Then, the reservation control unit 15 determines whether the larger of the acquired frequency usage rate and the ratio of the frequency band reserved for the service type to the entire band is smaller than a certain ratio with respect to the frequency usage rate reference. Judge. Here, when it is determined that the difference is small, the reservation control unit 15 assigns a band corresponding to the difference between the frequency usage standard and the actual frequency usage to the frequency band in FIG.
As shown in (1), a non-reserved band is searched and determined from the opposite side in the direction of searching for a frequency to be allocated to a line, and is reserved as a band that can be used only in this service type.

In the reserved bandwidth, the available bandwidth at that time can be used immediately with the corresponding service type, but the used bandwidth is used after the call using the relevant bandwidth releases the bandwidth. Only the service can use this band.

The reservation control unit 15 periodically updates the statistical information storage unit 1 for the service type for which the reserved band has been set.
4 to obtain the number of call connection requests per unit time. If the acquired number of call connection requests per unit time is equal to or less than the threshold derived from the frequency usage rate standard, the reservation control unit 15 determines that the number of call connection requests has decreased and that the reserved bandwidth is unnecessary. Release the reservation.

Next, the operation of this embodiment shown in FIG. 1 will be described with reference to the flowcharts of FIGS.
Now, in the DAMA satellite communication system shown in FIG.
The existing communication service is Sk (k = 1, 2,...,
Suppose there are N types of N).

A connection request of the service type Sk (1 ≦ k ≦ N) is transmitted from the mth slave station Rm (1 ≦ m ≦ n) to the master station C (step S1). The control unit 13 specifies the destination slave station in response to the request, and checks the consistency of the communication parameters and the like (step S2).
If the result is OK (Yes in step S3), a frequency band acquisition process (step S4) is performed. Thereafter, the communication line control unit 13 notifies the statistical information storage unit 14 that there has been a call connection request of the service type Sk (step S5).

The statistical information storage unit 14 receives the above notification and includes it in the number of call connection requests CRk of the service type Sk currently being collected (step S6). here,
The statistical information storage unit 14 calculates a call connection request rate CRn (t) per unit time from CRn for each service type Sn in Tsts units.

In the frequency band acquisition process (step S4), it is assumed that the communication line control unit 13 cannot acquire the frequency band required for communication (step S4).
No. 7). At this time, the communication line control unit 13 immediately transmits a call connection rejection notification to the slave station through the CSC frame processing unit 12 and the transmission / reception unit 11, and sets the reservation control unit 15
The service type Sk is notified that the call connection has been rejected due to insufficient frequency (step S8).

Upon receiving the above notification, the reservation control unit 15 acquires the frequency usage rate Pk of the latest service type Sk from the statistical information storage unit 14 (step S9). Then, the reservation control unit 15 selects the larger MAX (Pk, Rk) of the ratio Rk of the frequency usage rate Pk and the band reserved for the service type Sk to the entire frequency band.
And the held frequency use rate reference P0n (n = 1,
2,..., N) are compared with the frequency usage rate reference P0k for the service type Sk (step S1).
0).

Then, the reservation control unit 15 sets the MAX (P
k, Rk) is α (predetermined value) for P0k
It is determined whether it is smaller by at least% (step S11). Here, α is 0 <α <100. If so (Yes in step S11), the reservation control unit 15
Is P0 continuous from the higher frequency in the entire frequency band.
The communication line control unit 13 is notified to reserve the bandwidth of k-MAX (Pk, Rk) as a bandwidth dedicated to Sk (step S12).

Next, the reservation control unit 15 activates the Trsv timer (step S13). When the Trsv timer times out (step S14), the statistical information storage unit 14 sends the latest call connection request rate CRn per unit time (CRn). t) is obtained (step S15). Here, the time Trsv is longer than the time Tsts (Trsv> Tsts). Subsequently, the reservation control unit 15 sets the call connection request rate CRn per unit time.
It is determined whether (t) is smaller than βk (step S)
16). Here, βk can be calculated by the reservation control unit 15 from the frequency usage rate reference P0k and the average holding time as a reference. If CRn (t) ≧ βk (step S16
No), the process returns to step S12. CRn (t) <βk
If (Yes in step S16), the reservation control unit 15
The communication line control unit 13 is notified to cancel the reservation for the communication service Sk (step S17).

That is, in steps S13 to S17,
The reservation control unit 15 acquires the call connection request rate CRn (t) per unit time from the statistical information storage unit 14 for each Trsv (> Tsts) for the reserved communication service Sk,
If this is equal to or smaller than βk, the communication line control unit 13 is notified to release the reserved band.

As is clear from the above description, according to the present embodiment, when the traffic in the system is small, it is possible to provide a number of lines exceeding a predetermined reference for each communication service, When the number of available frequency bands is small and the number of available frequency bands is small, the number of lines in accordance with a predetermined service standard is distributed to each communication service. Therefore,
Since the "outgoing line fraction effect" in which a call having a large frequency bandwidth required for connection is less likely to be connected than a call having a small frequency bandwidth required for connection is suppressed, each communication service can be stably provided. .

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[0050]

As described above, according to the present invention, the frequency band is reserved according to the service conditions and the traffic conditions. Therefore, when only a small number of communication services out of the provided communication services have large traffic, Since there is no use restriction on the frequency resource used, the communication service can be provided to the maximum. Further, according to the present invention, when the traffic of a large number of communication services is large, the frequency resources are distributed according to the standard, so that the outgoing line fraction effect can be suppressed and each communication service can always be provided stably. .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a master station in a DAMA satellite communication system that implements a frequency allocation control method according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an operation of frequency band reservation in a master station shown in FIG.

FIG. 3 is a flowchart showing the first half of the operation of the master station shown in FIG. 1;

FIG. 4 is a flowchart showing the latter half of the operation of the master station shown in FIG. 1;

FIG. 5 is a block diagram showing a configuration of a DAMA satellite communication system to which a frequency allocation control method according to the present invention is applied.

FIG. 6 is a diagram showing a frequency allocation of the DAMA satellite communication system shown in FIG. 5;

FIG. 7 is a diagram showing a frequency arrangement when frequency bands allocated to slave stations are different in the DAMA satellite communication system shown in FIG. 5;

[Explanation of symbols]

 C master station R1,..., Rn slave station S satellite 11 transmission / reception section 12 CSC frame processing section 13 communication line control section 14 statistical information storage section 15 reservation control section

Claims (23)

(57) [Claims] 1. An arbitrary one of a plurality of slave stations notifies a communication request to another slave station to a master station via a satellite using a common control channel via a satellite. By assigning the required bandwidth and using the common control channel to indicate the bandwidth to be used for each of the communication requesting slave station and the communication connection destination slave station, the communication requesting slave station and the communication are communicated with each other. In a DAMA satellite communication system in which a connected slave station can communicate voice and data via the satellite, the master station obtains the number of used lines for each service type and calculates a frequency usage rate. Statistic information storage unit that holds the frequency usage standard for each service type, and when notified of a connection failure related to a specific service type,
Reservation control for obtaining the latest frequency usage rate for the specific service type from the statistical information storage unit and reserving a predetermined frequency band so that it can be used only in the specific service type when a predetermined condition is satisfied. A DAMA satellite communication system comprising: 2. The statistical information accumulating section tallies up the number of call connection requests for each service type, calculates a call connection request rate per unit time, and the reservation control section, Periodically acquiring the call connection request rate from the statistical information storage unit for the type, and releasing the reserved predetermined frequency band when the obtained call connection request rate becomes lower than a predetermined rate. The DAM of claim 1, wherein
A satellite communication system. 3. The predetermined condition includes: comparing a larger one of the obtained recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. The DAMA satellite communication system according to claim 1, wherein the larger one is smaller than the frequency use reference by a predetermined percentage or more. 4. The DAMA satellite communication system according to claim 3, wherein said predetermined frequency band is a frequency band corresponding to a difference between said larger frequency band and said frequency use reference. 5. An arbitrary one of a plurality of slave stations notifies a communication request for another slave station to a master station via a satellite using a common control channel, and based on the communication request, the master station. By assigning the required bandwidth and using the common control channel to indicate the bandwidth to be used for each of the communication requesting slave station and the communication connection destination slave station, the communication requesting slave station and the communication are communicated with each other. In a DAMA satellite communication system in which a slave station of a connection destination can communicate voice and data via the satellite, the master station counts the number of call connection requests for each service type, and performs call connection per unit time. Calculate the request rate, obtain the number of lines used for each service type, hold a statistical information storage unit for calculating the frequency usage rate, hold the frequency usage standard for each service type, and Upon receipt of the notification of connection failure,
Obtain the latest frequency usage rate for the specific service type from the statistical information storage unit, and when a predetermined condition is satisfied, reserve a predetermined frequency band so that it can be used only in the specific service type, The call connection request rate is periodically acquired from the statistical information storage unit for the specific service type for which the reservation has been made, and when the acquired call connection request rate is lower than a predetermined rate, the reserved predetermined connection type is used. A DAMA satellite communication system, comprising: 6. The predetermined condition includes: comparing a larger one of the acquired recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. 6. The DAMA satellite communication system according to claim 5, wherein the larger one is smaller than the frequency use reference by a predetermined percentage or more. 7. The DAMA satellite communication system according to claim 6, wherein said predetermined frequency band is a frequency band corresponding to a difference between said larger frequency band and said frequency use reference. 8. A master station used in a DAMA satellite communication system, wherein any one of a plurality of slave stations sends a communication request to another slave station via a satellite. To the master station using a common control channel, and based on the communication request, the master station allocates a necessary band and uses the common control channel to communicate with the slave station of the communication request source and the slave station of the communication connection destination. By instructing each of the bands to be used, the communication requesting slave station and the communication connection destination slave station can perform voice and data communication via the satellite in the DAMA satellite communication system. The master station obtains the number of used lines for each service type and calculates a frequency usage rate, and stores a frequency usage standard for each service type, and stores a specific service type. When receiving a connection failure notification in accordance with,
Reservation control for obtaining the latest frequency usage rate for the specific service type from the statistical information storage unit and reserving a predetermined frequency band so that it can be used only in the specific service type when a predetermined condition is satisfied. And a master station of the DAMA satellite communication system. 9. The statistical information accumulating section tabulates the number of call connection requests for each service type to calculate a call connection request rate per unit time, and the reservation control section calculates the specific service for which the reservation has been made. Periodically acquiring the call connection request rate from the statistical information storage unit for the type, and releasing the reserved predetermined frequency band when the obtained call connection request rate becomes lower than a predetermined rate. 9. The DAM according to claim 8, wherein:
A The master station of the satellite communication system. 10. The predetermined condition is to compare a larger one of the obtained recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. 9. The master station of the DAMA satellite communication system according to claim 8, wherein the larger one is smaller than the frequency use standard by a predetermined percentage or more. 11. The master station of the DAMA satellite communication system according to claim 10, wherein the predetermined frequency band is a frequency band corresponding to a difference between the larger one and the frequency use reference. 12. A master station used in a DAMA satellite communication system, wherein any one of a plurality of slave stations sends a communication request to another slave station via a satellite. Notify to the master station using a common control channel, and based on the communication request, the master station allocates a necessary band, and uses the common control channel to each of the communication request source slave station and a communication connection destination slave station. The parent station of the DAMA satellite communication system enables the slave station of the communication request source and the slave station of the communication connection destination to communicate voice and data via the satellite by designating the band to be used. The station collects the number of call connection requests for each service type, calculates the call connection request rate per unit time, obtains the number of used lines for each service type, and calculates the frequency usage rate. An information storage unit, holding the frequency use criteria for each service type, when receiving a notification of connection failure according to a particular service type,
Obtain the latest frequency usage rate for the specific service type from the statistical information storage unit, and when a predetermined condition is satisfied, reserve a predetermined frequency band so that it can be used only in the specific service type, The call connection request rate is periodically acquired from the statistical information storage unit for the specific service type for which the reservation has been made, and when the acquired call connection request rate is lower than a predetermined rate, the reserved predetermined connection type is used. A master controller of the DAMA satellite communication system, comprising: 13. The predetermined condition includes: comparing a larger one of the obtained recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. The DAMA according to claim 12, wherein the larger one is smaller than the frequency use standard by a predetermined percentage or more.
Master station of satellite communication system. 14. The master station of the DAMA satellite communication system according to claim 13, wherein the predetermined frequency band is a frequency band corresponding to a difference between the larger frequency band and the frequency use reference. 15. An arbitrary one of a plurality of slave stations notifies a communication request to another slave station to a master station via a satellite using a common control channel, and based on the communication request, the master station. By assigning the required bandwidth and using the common control channel to indicate the bandwidth to be used for each of the communication requesting slave station and the communication connection destination slave station, the communication requesting slave station and the communication are communicated with each other. In a DAMA satellite communication system in which a connected slave station can perform voice and data communication via the satellite, a frequency allocation control method at the master station, wherein a frequency band is controlled according to service conditions and traffic conditions. A frequency allocation control method for a DAMA satellite communication system. 16. The reservation of the frequency band is performed by the DAM.
The method according to claim 15, wherein the method is performed from one end of a usable frequency band in the A-satellite communication system. 17. When there is the reserved frequency band, a search is made for a region where a band equal to or more than the bandwidth required by the line is vacant from the one end, and the determined frequency band is determined. 17. The DAMA satellite communication system according to claim 16, wherein when there is no available area, a search is made for a region where a band equal to or more than the bandwidth required by the line is vacant from the other end of the usable frequency band. Frequency allocation control method. 18. A slave station of any one of a plurality of slave stations notifies a communication request to another slave station to a master station via a satellite using a common control channel, and based on the communication request, the master station By assigning the required bandwidth and using the common control channel to indicate the bandwidth to be used for each of the communication requesting slave station and the communication connection destination slave station, the communication requesting slave station and the communication are communicated with each other. A method of reserving bandwidth in the master station in a DAMA satellite communication system in which a connected slave station can communicate voice and data via the satellite, wherein a frequency use standard for each service type is held. Acquiring the number of used lines for each service type, calculating the frequency usage rate, and receiving a notification of connection failure relating to the specific service type, receiving the latest frequency usage rate for the specific service type. Acquiring a predetermined frequency band and, when a predetermined condition is satisfied, reserving a predetermined frequency band so that the frequency band can be used only in the specific service type. 19. The predetermined condition includes: comparing a larger one of the obtained recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. 19. The DAMA according to claim 18, wherein the larger one is smaller than the frequency use standard by a predetermined percentage or more.
Bandwidth reservation method for satellite communication system. 20. The band reservation method for a DAMA satellite communication system according to claim 19, wherein the predetermined frequency band is a frequency band corresponding to a difference between the larger one and the frequency use reference. 21. An arbitrary one of a plurality of slave stations notifies a communication request for another slave station to a master station via a satellite using a common control channel, and based on the communication request, the master station. By assigning the required bandwidth and using the common control channel to indicate the bandwidth to be used for each of the communication requesting slave station and the communication connection destination slave station, the communication requesting slave station and the communication are communicated with each other. A method for reserving / releasing a band at the master station in a DAMA satellite communication system in which a slave station of a connection destination can communicate voice and data via the satellite, wherein a frequency use standard for each service type is set. Holding, totaling the number of call connection requests for each service type, calculating the call connection request rate per unit time, obtaining the number of lines used for each service type, calculating the frequency usage rate, and statistics Information storage unit When a connection failure notification is received for a specific service type, the latest frequency usage rate for the specific service type is obtained, and when a predetermined condition is satisfied, only the specific service type is used. A predetermined frequency band is reserved so that the call connection request rate is periodically acquired for the specific service type for which the reservation has been made, and when the acquired call connection request rate becomes lower than the predetermined rate. Releasing a reserved predetermined frequency band from the reserved bandwidth of the DAMA satellite communication system. 22. The predetermined condition includes: comparing a larger one of the acquired recent frequency usage rate and a ratio of a band reserved for the specific service type with the frequency usage standard of the specific service type. 22. The DAMA according to claim 21, wherein the larger one is smaller than the frequency use standard by a predetermined percentage or more.
Bandwidth reservation / release method for satellite communication system. 23. The method of claim 22, wherein the predetermined frequency band is a frequency band corresponding to a difference between the larger frequency band and the frequency use reference.