JP2888112B2 - Satellite communication slot allocation device and satellite communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot allocating apparatus incorporating a reservation in a satellite communication system adopting slotted random access and a satellite communication system.

[0002]

2. Description of the Related Art In a satellite communication system including a central station and a plurality of peripheral stations, a communication system from a peripheral station to the central station is based on a random access method with a slot and often uses a reservation method together. FIG. 6 shows the configuration of the central office on the spot. In FIG. 6, 1 is a transmission control unit, 2 is a reception control unit, 3 is a delivery confirmation control unit, and 4 is a reservation control unit. FIG. 7 shows, for example, GLOBECOM 86, Dec19.
86 "AA / TDMA-ADAPTIVE SATEL
LITE ACCESS METHOD FORMIN
I-EARTH STATION NETWORKS "
3 is an operation timing chart shown in FIG. In FIG. 7, 5
Is the data reception timing of the central station, and 6 is the data transmission timing of the peripheral station A that issues the reservation request. 7 is peripheral station A
, And may also serve as the head of the reservation data. Reference numeral 8 denotes a delivery acknowledgment signal to the peripheral station A, which often serves as a slot assignment signal to the peripheral station in response to a reservation request and transmission inhibition information to other peripheral stations.
Reference numeral 9 denotes reservation data of the peripheral station A. 10 is the data transmission timing of the peripheral station B, 11 is the data generation timing of the peripheral station B, 12a and 12b are the generated data of the peripheral station B,
13a and 13b are transmission data of the peripheral station B, and 14 is an acknowledgment signal to the peripheral station B. Reference numeral 15 denotes a transmission prohibition period of the peripheral station B.

Next, the operation will be described. In FIG. 6, the central station transmits an acknowledgment signal from the acknowledgment control section 3 to the peripheral station via the transmission control section 1 when the data from the peripheral station is normally received by the reception control section 2. FIG.
When the reservation control unit 4 receives the reservation request from the peripheral station from the reception control unit 2, the slot allocation information is assigned to the peripheral station, and the slot assigned to the peripheral station that has issued the reservation request to the other peripheral stations. The transmission prohibition information for prohibiting the transmission at the time is transmitted through the transmission control unit 1.

The operation timing including peripheral stations will be described with reference to FIG. The transmission data 7 generated in the peripheral station A is transmitted to the central station based on the data generation timing 6. When the transmission data 7 is normally received, the central station transmits the acknowledgment signal 8 to the peripheral station A. If the peripheral station cannot receive this acknowledgment signal, it retransmits the data as if it was lost due to collision or the like. This operation is called a slotted random access method. It is also considered to use a reservation method in combination with the slotted random access method. In this case, a part of the normal transmission data 7 is often used as a reservation request from a peripheral station.

FIG. 7 shows a case where the peripheral station A issues a reservation request. The transmission data 7 of the peripheral station A includes a reservation request, and the central station prohibits transmission of slot allocation information to the peripheral station A and transmission to other peripheral stations at the time of the slot allocated to the peripheral station A. The transmission prohibition information to be transmitted is transmitted as the delivery confirmation signal 8. The peripheral station A continuously transmits data on the slot to which the reservation data 9 is allocated based on the slot allocation information. In FIG. 7, the peripheral station B is represented as another example of the peripheral station. In the peripheral station B, the data generation timing 11 and the data transmission timing 10 are separately described. Data 1 generated at data generation timing 11
2a is transmitted to the central station as transmission data 13a, and when the transmission data 13a is normally received, the central station transmits an acknowledgment signal 14 to the peripheral station B. If the data 12b generated at the data generation timing 11 of the peripheral station B is the time of the slot allocated to the peripheral station A, that is, the transmission prohibition time 15 for the peripheral station B, the transmission is waited until the transmission prohibition time 15 ends. The data 13b is transmitted to the central office.

[0006]

In the conventional satellite communication system, a reservation system is also used based on the above procedure.
The time of the slot allocated to the peripheral station that has made the reservation request is during the transmission prohibition period for other peripheral stations. Data generated by other peripheral stations during this period cannot be transmitted as transmission data until the end of the transmission prohibition time, and transmission starts when the transmission prohibition time ends. There is a problem that the data transmitted on the line is concentrated and the satellite line is easily congested.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and data transmission generated by another peripheral station based on a reservation request by a peripheral station when there is a large amount of traffic is prohibited. The purpose is to alleviate the situation in which the satellite lines are congested after a lapse of time and are congested.

[0008]

SUMMARY OF THE INVENTION A satellite communication slot allocating apparatus according to the present invention includes a traffic situation detecting means for detecting a traffic amount from each peripheral station, an output of the traffic situation detecting means, and a communication reservation from each peripheral station. Receiving control means for determining an assigned slot of each peripheral station in response to the received traffic, and when the traffic volume from each peripheral station is larger than a predetermined value, the number of consecutive allocated slots of the assigned slot is reduced and given intermittently. When the traffic volume from each peripheral station is smaller than a predetermined value, the number of consecutively allocated slots is increased. In the satellite communication slot allocating device according to the second aspect, the traffic condition detecting means further includes a traffic amount table for storing the traffic amount from each peripheral station for a predetermined time in the past, and the reservation control means includes the same. The number of consecutive allocated slots is determined by looking at the traffic volume table. According to a third aspect of the present invention, there is provided a satellite communication slot allocating apparatus, wherein the traffic situation detecting means further comprises a test data transmitting / receiving means, and transmits test data to each peripheral station prior to transmission. The delay of the reply data from the station is transmitted to the reservation control means, and the reservation control means decides the number of consecutively allocated slots by referring to the reply result. A satellite communication system according to a fourth aspect of the present invention receives a central station having the satellite communication slot allocating device according to the first aspect, first allocation information having a small number of slots, and second allocation information having a large number of slots. It has multiple peripheral stations for transmitting data.

[0009]

The satellite communication slot allocating apparatus according to the present invention, when receiving a slot allocation reservation from each peripheral station, corresponds to the traffic volume from each peripheral station detected by the traffic situation detecting means. In the case where there is a large number of slots, slots are allocated intermittently and the number of consecutive slots is reduced one time. According to the second aspect of the present invention, as the reference traffic amount, a received traffic amount for a certain period in the past is stored, and slots are allocated based on the stored traffic amount. In the apparatus according to the third aspect, slots are allocated to the reference traffic amount based on the response status of test data sent prior to transmission. In the system of claim 4, the central station transmits a plurality of types of slot allocation information according to the traffic volume, and the peripheral stations receiving the information transmit data continuously for the corresponding number of slots.

[0010]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the central office.
Reference numeral 4 is the same as that shown in FIG. 6 shown in the prior art, and there are 16 traffic situation detecting units as new components. As a specific configuration of the traffic situation detection unit 16, there is, for example, a traffic volume pattern storage table that stores a traffic situation pattern for a fixed time in the past. This stores the amount of communication every 10 minutes, 15 minutes or 30 minutes from 0:00 to 24:00 in one day. Another example is the last 10
It may be a table storing the transmitted / received data amount for minutes, 15 minutes or 30 minutes. FIG. 2 shows a timing chart including peripheral stations according to the present embodiment. In FIG. 5, reference numerals 5 to 8 and 10 to 14 are the same as those in FIG. 7 shown in the prior art, but the reservation data 9 of the peripheral station A and the transmission inhibition time 15 of the peripheral station B shown in FIG. Are 9a, 9b and 15a, 15b
, The slot allocation to the peripheral station A is decomposed, but the waiting time for the peripheral station B is reduced, and congestion after the communication of the peripheral station A ends can be prevented from concentrating as in the related art.

Next, the operation of this embodiment will be described. In FIG. 1, the operation when the data from the peripheral station is normally received by the reception control unit 2 at the central station is the same as that of the prior art. Next, consider a state in which traffic has increased. The traffic situation detection unit 16 detects the traffic situation in the network based on the information from the transmission control unit 1 and the reception control unit 2,
This is transmitted to the reservation control unit 4. When the reservation control unit 4 receives a reservation request from the peripheral station from the reception control unit 2, the reservation control unit 4 refers to the communication pattern amount table described above, sees the traffic amount in the corresponding time zone, and determines the traffic in the network. The slot assignment information set to the value of the time allocation according to the situation is sent to the peripheral station. To other peripheral stations, transmission prohibition information for prohibiting transmission is transmitted through the transmission control unit 1 during the slot time allocated to the peripheral station A that made the reservation.

FIG. 3 is a flowchart illustrating the operation of the reservation control section 4. When the reservation control unit 4 receives the reservation request from the peripheral station from the reception control unit 2 in step S1, the reservation control unit 4 changes the allocation according to the traffic situation in the network transmitted from the traffic situation detection unit 16 in step S2. That is, if the traffic volume is small, the slot is continuously allocated in step S3, and if the traffic volume is large, the slot is discontinued in step S4. Set transmission prohibition information. The operation timing including peripheral stations will be described with reference to FIG. The transmission data 7 of the peripheral station A making the reservation request includes the reservation request. Upon receiving this, the central station sends slot assignment information to the peripheral station A. The transmission prohibition information for prohibiting the transmission at the time of the slot allocated to the peripheral station A that has made the reservation is transmitted as a delivery confirmation signal 8 to the other peripheral stations.

FIG. 2 shows a timing chart when the traffic volume in the network is large. In the figure, the reservation data transmitted by the peripheral station A which has issued the reservation request is divided into two parts 9a and 9b because the traffic volume is large in this time zone.
Is transmitted to the central office. In the peripheral station B, the transmission prohibited time is divided into 15a and 15b, and the generated data 12b can be transmitted without waiting for the end of the entire transmission prohibited time. This means that each peripheral station sends data that stays due to the existence of the transmission prohibition time, including other peripheral stations, at the end of the total transmission prohibition time or at the end of the divided transmission prohibition time. Or according to the traffic situation in the network. In this way, when the traffic volume is large, it is alleviated that the data to be transmitted on the satellite line is congested.

Embodiment 2 FIG. In the above embodiment, the traffic situation in the network is detected in the central station by the information from the transmission control unit 1 and the reception control unit 2, for example, in a traffic volume pattern storage table of the traffic situation detection unit 16. This is another method, the traffic situation detector 16
Can detect the traffic situation of the network using the test data 17 and obtain the same effect.
FIG. 4 shows a second embodiment.

In general, as the traffic volume increases, it takes time to respond to the communication data.
The operation of this embodiment is as follows. The test data 17 transmitted from the traffic situation detecting unit 16 is multiplexed into communication data 19 by the multiplexing / demultiplexing unit 18 and transmitted from the transmission control unit 1 to, for example, several hundred peripheral stations. A response signal to the test data transmitted from the peripheral station is sent from the reception control unit 2 of the central station to the demultiplexing unit 18, separated from the communication data 19, and sent to the traffic situation detecting unit 16 as a response signal 20. When traffic becomes heavy, this response returns only, for example, 10. The traffic situation detector 16 detects the traffic situation in the network based on the test data 17 and the response signal 20 to the test data 17 and notifies the reservation controller 4 of the traffic situation. The reservation control unit 4 determines the congestion degree of the traffic situation according to the response rate,
By changing the time allocation of the slots to be allocated, the same effect as in the embodiment can be obtained. For example, if the degree of congestion is high, the number of consecutive slots allocated is shortened.

Embodiment 3 Another embodiment will be described. The first embodiment requires a communication amount pattern storage table, and the second embodiment requires, for example, test communication to several hundred peripheral stations. Consider that these are realized with a simpler configuration. In satellite communication, the idea of resending unreachable data is common. The large number of retransmissions means that traffic is congested. Therefore, it is possible to easily estimate the traffic amount by storing the retransmission data within the immediately preceding fixed time. In this embodiment, the retransmission data from the reception control unit 2 is stored in the traffic situation detection unit 16 for a certain period of time . FIG. 5 is a diagram showing the configuration of the present embodiment.

The operation of this configuration is as follows. The traffic situation detection unit 16 stores the retransmission data from the reception control unit 2 for a certain period of time. In response to a slot allocation request from the peripheral station A or the like, the reservation control unit 4 is notified of the stored retransmission data amount. The reservation control unit 4 sends slot assignment information to the peripheral station A and the like based on the retransmission data, and sends transmission inhibition information to the other peripheral stations B and the like.

[0018]

As described above, according to the present invention, the traffic situation detecting means is provided, and the number of slots continuously allocated is changed in accordance with the traffic volume so as to be provided intermittently. Even in the case where there is a large number, there is an effect that communication concentration after the end of the transmission prohibition time, that is, a congestion state can be avoided. According to the second aspect of the present invention, there is an effect that an accurate traffic amount can be predicted based on the results already obtained, and a congestion state can be accurately avoided. According to the invention of claim 3, there is an effect that the traffic amount can be predicted based on simple data, and congestion can be avoided. According to the invention of claim 4, since the peripheral stations transmit data by the number of slots corresponding to the allocation information from the central station, there is an effect that a load distribution system that avoids congestion can be constructed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a central office according to an embodiment of the present invention.

FIG. 2 is an operation timing chart showing a communication situation between a central station and peripheral stations according to an embodiment of the present invention.

FIG. 3 is an operation flowchart of a central office according to an embodiment of the present invention;

FIG. 4 is a diagram showing a configuration of a central office according to another embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a central office according to still another embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a conventional central office.

FIG. 7 is an operation timing chart between a central station and a peripheral station according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission control part 2 Reception control part 3 Delivery confirmation control part 4 Reservation control part 16 Traffic situation detection part

Claims (4)

(57) [Claims] A traffic condition detecting means for detecting an amount of traffic from each peripheral station; a reservation control means for receiving an output of the traffic condition detecting means and a communication reservation from each peripheral station to determine an assigned slot of each peripheral station. When the traffic volume from each peripheral station is larger than a predetermined value, the number of continuous allocation slots of the allocation slots is reduced and given intermittently, and the traffic volume from each peripheral station is smaller than the predetermined value. In such a case, a satellite communication slot allocating device of the central station which gives a large number of continuous allocation slots of the allocation slots. 2. The traffic situation detecting means is provided with a traffic quantity table for storing a traffic quantity from each peripheral station for a fixed time in the past, and the reservation control means determines the number of consecutively allocated slots by referring to the traffic volume table. The satellite communication slot allocating apparatus according to claim 1, wherein: 3. The traffic situation detecting means includes test data transmitting / receiving means, transmits test data to each peripheral station prior to transmission, transmits delay of reply data from each peripheral station to reservation control means, 2. A satellite communication slot allocating apparatus according to claim 1, wherein said control means determines the number of consecutive allocated slots in view of said reply result. 4. A satellite communication system comprising a central station and a plurality of peripheral stations communicating with the central station and transmitting a communication reservation to the central station at the start of communication. A traffic situation detecting means for detecting an amount of traffic from the station; and a reservation control means for receiving an output of the traffic situation detecting means and receiving the communication reservation from each peripheral station to determine an assigned slot of each peripheral station. When the traffic volume from the station is larger than a predetermined value, the first information is transmitted to reduce the number of consecutive allocated slots of the allocated slot and to be provided intermittently. When the traffic amount is smaller than the predetermined value, the second station transmits second information that indicates that the number of consecutively allocated slots is large, and the peripheral station transmits the first information or the second information; Percent Satellite communication system and to transmit the data in response to rely was slot.