JPH088800A - Reservation method for dynamic interruption slot by pama system - Google Patents

Abstract

PURPOSE:To make it possible to assign other lines to the slots to which the lines are assigned by a DAMA system by a PMMA system, without disconnecting the communication of the lines, in the satellite communication system by an AA/TDMA system. CONSTITUTION:When a line is already assigned to an object slot by a DAHA system when the line interruption request by a PAMA system is generated for a slot for DAMA system, the assignment of the line is moved to other free slot and the line is assigned to the object slot which becomes free by the movement by the PAMA system. Thus, the dynamic slot assignment in communication by the PAMA system is enabled and the effective use of the slot becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slot for performing communication between one central station and a large number of peripheral stations via a satellite by a DAMA (request allocation multiple access) and PAMA (fixed allocation multiple access) system. The present invention relates to a reservation method, and more particularly, to a reservation method for dynamically allocating another line by the PAMA method to a slot already allocated by the DAMA method.

[0002]

2. Description of the Related Art As shown in FIG. 1, a basic configuration example of a satellite communication system is one in which one central station 1 and many peripheral stations 3 communicate with each other via a satellite 2. In the case of the star configuration as shown in FIG. 1, when transmitting data from the central station 1 to the peripheral station 3, a time division multiplexing (TDM) method using a broadcast type channel is used. When transmitting from the central station 1 to the central station 1, a multiple access method is mainly used in which a plurality of peripheral stations jointly use one satellite channel for communication, and AA is used as a channel access method.
/ TDMA method is used.

The AA / TDMA system is a multiple access system in which a random access slot Aloha system (RA / TDMA system) and a slot reservation allocation system (DA / TDMA system) are combined, but it is usually mainly a random access slot Aloha system. It is functional and is free to send data to each satellite on the satellite channel. Therefore, data transmitted from two or more peripheral stations to the same slot at the same time collide with each other and are lost. Therefore, the AA / TDMA system is not used for a line that requires continuous data transmission such as a voice line. Not applicable.

Generally, in the case of continuous communication without data collision such as voice line, Japanese Patent Laid-Open No. 58-204638.
No. 63-209329 and Japanese Patent Laid-Open No. 63-209329.
er Carrier) DA using a single line
The MA method is used. Therefore, when performing continuous communication such as a voice line on the satellite communication system using the AA / TDMA system, a part of the slot of the satellite channel is DA
Secured as a slot exclusively for allocation by the MA method,
Communication is performed using this slot. Normal,
One slot for the DAMA system is provided for each frame of a bidirectional satellite channel, and the slot is further divided into several subslots, which are used as channels occupied by individual lines. The line allocation process by the DAMA method to each sub-slot is
The AA / TDMA transmission path on the satellite channel is used to reserve the sub-slot, and then the reserved sub-slot is used to transmit / receive actual data.

Further, like the Japanese Patent Laid-Open No. 2-95034, the slot for the DAMA method can be assigned by the PAMA method in addition to the DAMA method in response to a line assignment request. Is. Therefore, as described in Japanese Patent Application Laid-Open No. 61-67341, the central processing unit of the slot reservation processing by the DAMA method collectively manages the line allocation by both DAMA and PAMA methods. However, DAMA, P
Which method of AMA is used to reserve a slot is manually set, and it is not automatically switched according to the use condition of the line as described in Japanese Patent Laid-Open No. 2-95034. Unlike the DAMA method, which reserves a slot after a line allocation request is made, the PAMA method is a method in which a slot to which a line is allocated is secured in advance. Therefore, normally, the slot reservation by the PAMA method has a higher priority than the slot reservation by the DAMA method, and when the importance of the line assigned to the slot is high, the slot reservation by the PAMA method is mainly used.

FIG. 4 shows an example of a frame structure on the satellite channel and an example of a slot structure in the satellite frame when the slot for the DAMA system is provided. In FIG. 4, DAM
The slot 33 for the A system has several sub-slots 3
The sub-slot 34 is divided into four, and each sub-slot 34 is occupied by one line assigned to the sub-slot by the DAMA method. In addition, as described above, each sub-slot 34
Can also be reserved and assigned by the PAMA method.

[0007]

The sub-slot in the slot for the DAMA method described above has the DAMA method and the PAMA method.
When allocating lines with both methods mixed,
Another line may be assigned by the PAMA method to a subslot to which a line has already been assigned by the DAMA method. In such a case, in the conventional slot reservation by the PAMA method, it is necessary to forcibly cancel the already-assigned allocation by the DAMA method, release the target subslot once, and then again allocate the line by the PAMA method. That is, the line that has already been communicating using the sub-slot allocated by the DAMA method is
There is a problem that the line is forcibly disconnected when a line allocation request by the method occurs.

[0008]

An object of the present invention is to provide a dynamic interrupt which makes it possible to allocate another line to the sub-slot to which a line has already been allocated in the DAMA system by the PAMA system without disconnecting the communication of the line. It is to provide a slot excess method.

[0009]

According to the slot reservation method of the present invention, a part of the slots according to the AA / TDMA method is DA.
In a satellite communication system which is secured as a slot for the MA system and uses the slot for the DAMA system and the PAMA system, a slot reservation order by the DAMA system and the PAMA system is set to each sub-slot in the DAMA system slot. , If the target sub-slot is already allocated by the DAM A method when the line allocation request is generated by the PAMA method and the line is in use, DAM
The allocation of the line is moved to another sub-slot which has already been released due to the allocation of the A system while keeping the synchronization, and another line of the PAMA system is allocated to the target sub-slot to which the line is moved. It is characterized by performing allocation.

For example, DAMA system line slots are assigned to sub-slots from the highest sub-slot number, and PAMA system line slots are assigned from the lowest sub-slot number. Are already assigned by the DAMA method, the lines of this target subslot are sequentially moved from the one with the highest subslot number to an empty subslot, and the PAMA system line is assigned to the moved target subslot. .

In the slot reservation system of the present invention, A
The central station that constitutes the A / TDMA system and the plurality of peripheral stations that compose the satellite communication system with this central station are respectively DAM.
It has an A controller, and these DAMA controllers are characterized by having all the allocation information of the lines by the DAMA and PAMA systems on the satellite channel.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. In the satellite communication system of the present invention, as shown in FIG. 1, when one central station 1 and a large number of peripheral stations 3 are configured to communicate via satellites 2, the central station 1 to the peripheral stations A time division multiplexing (TDM) method using a broadcast type channel is used when transmitting data to the 3rd station, but when transmitting from the peripheral station 3 to the central station 1, a plurality of peripheral stations are mainly one satellite. A multiple access method is used in which channels are jointly used for communication, and an AA / TDMA method is used as a channel access method.

On the satellite communication system using the AA / TDMA system, a part of the slots on the satellite channel originally used in the AA / TDMA system are used in order to perform continuous communication without data collision such as voice line. , A slot dedicated to allocation by the DAMA method is secured, and communication by the DAMA method is performed using this slot.
One slot for this DAMA system is provided for each frame of a bidirectional satellite channel. That is, this DAM is also provided on the transmission line from the central station 1 to the peripheral station 3 by the TDM method.
One slot for the A system is provided for each frame. In addition, PA to this DAMA slot
Line allocation by the MA method is also possible.

FIG. 2 is a block diagram of the central station in the present invention. In the figure, when the central station receives a signal from each peripheral station via the satellite by the antenna 11, the receiving section 12 performs a data receiving process. Then, the received data is sent to the received data processor 13 for processing such as packet assembly and the like, and is taken out as received data.
Among the data received by the AA / TDMA system, DAMA
The control information of the slot reservation request according to the method is sent from the reception data processor 13 to the DAMA controller 14, and the slot reservation processing according to the DAMA method is performed.
After the slot reservation processing, the information is sent from the DAMA controller 14 to the transmission data processor 15 and DAMA of the data processed by the transmission data processor 15 is DAMA.
Data to be transmitted using the system slot is subjected to transmission processing based on the slot reservation information. The transmission data transmitted from the transmission processor 15 to the multiplexing unit 16 is multiplexed with the timing signal generated by the timing signal generation unit 17 and the signal generated by the control signal generation unit 18 and transmitted to the transmission unit 19, and the antenna 11 Sent to each peripheral station.

FIG. 3 is a block diagram of a peripheral station according to the present invention. Peripheral stations receive signals from the central station via antenna 21
When it is received, the data is processed by the reception unit 22 and output to the reception data processor 23, and the reception data is extracted. Also, D
Control information regarding the AMA slot is sent to the DAMA controller 24. The DAMA controller 24 instructs the transmission data processor 25 to assign a line to the slot for the DAMA method based on the slot reservation information processed by the central station. Of the signals received by the antenna 21, the synchronization signal is output to the frame synchronization unit 26 to maintain synchronization with the central station. Of the control signals, the signal of the retransmission request is sent to the retransmission control unit 27, and instructs the transmission data processor 25 to retransmit the data. Based on the control information received from the DAMA controller 24, the data sent to the transmission data processor 25 is discriminated by the transmission slot management unit 28 based on the control information received from the DAMA, PAMA system or AA / TDMA system. It is sent to 29 and output from the antenna 21 to the central station.

The frame structure on the satellite channel according to the AA / TDMA system and the slot structure for the DAMA system provided in the frame are as shown in FIG. The satellite frame has a control information area 31 in which control information is inserted and AA /
It is composed of a data area 32 into which a data packet transmitted by the TDMA method is inserted. The data area 32 is divided into slots into which transmission packets from each station are inserted, and the last slot in this slot group is set as the DAMA system slot 33. The slot 33 for the DAMA method is further divided into several sub-slots 34, and slot reservation by the DAMA method is performed in units of this sub-slot. The line allocation reservation process for the sub-slot 34 by the DAMA method is performed by using the transmission line by the AA / TDMA method on the satellite channel, and the target sub-slot is reserved by this, and the actual data transmission / reception is performed in this sub-slot. 34 is used. Hereinafter, the slot means a subslot in the slot for the DAMA method.

Next, the structure in the slot (= subslot 25) will be described. As shown in FIG. 4, each slot 34 has a header field 35 in which control information is stored.
And a data field 3 that stores the actual transmission data
6 and 6. Information stored in the header field as control information includes DAMA method and PAM.
There is an identifier that indicates which method of allocation is the A method, and an identifier that indicates the allocation change state of each slot, one bit for each identifier in total 2
A field of bits is provided.

The slot assignment change state identifier is an identifier provided for enabling the dynamic interrupt reservation by the PAMA method, which is the object of the present invention, and represents the assignment movement state of the same slot in the next frame. This slot allocation change status identifier has a value of 0 or 1 and has the following meanings. Slot allocation change status identifier 1: Requesting change 0: Normal Usage of the slot allocation change status identifier during actual operation will be described in detail later.

Next, the DAMA method and P for each slot
With reference to FIG. 5, a description will be given of the line allocation procedure by the AMA system and the operation details when another line allocation request by the PAMA system is made to the slot being line-allocated by the DAMA system. First, DAMA method and PAM
The allocation order according to method A is specified. When a line allocation request is made to a certain slot by the DAMA method, as shown in FIG. 5A, in the case of allocation to each slot by the PAMA method, each slot by the DAMA method is selected from the smallest slot number. When assigning to slots, the slot numbers are set to be assigned in descending order.

In this way, the slots are DAMA, PA
When the MA method is sequentially assigned, as shown in FIG. 5B, the slot numbers to be assigned next match at a certain point in time, and the number of assignable slots is exhausted, resulting in either DAMA or PAMA. It becomes impossible to assign even by the method. By the way, in the line assignment by the DAMA method, when the communication of the line is completed, the assignment to the slot is released, and new lines can be sequentially assigned. Although the slot assignment is released asynchronously, the slot assignment by the DAMA method is performed in descending order of the slot number.
Even if the slots to be sequentially allocated by the PAMA method are already allocated by the DAMA method and the allocation by the PAMA method cannot be performed any more, FIG.
As shown in (c), there are empty slots in the area allocated by the DAMA method in a worm-eating state.

Therefore, when the slot reservation is made by giving priority to the line allocation by the PAMA method, FIG.
As shown in (d), even if the slot to be assigned next by the PAMA method has already been assigned by the DAMA method and is in use, the assignment has already been released among the slots assigned by the DAMA method. If the allocation of the line is moved to the vacant slot of, the source slot becomes vacant, and the line can be allocated to the slot by the PAMA method. That is, if the target slot has already been allocated by the DAMA method and the line is in use when a slot allocation request by the PAMA method has occurred, another slot which has already been released and is empty by the DAMA method is allocated. Move the line assignment to. This movement of the slot is performed dynamically during communication by maintaining the synchronization, so that another line can be assigned to the target slot by the PAMA method.

Further, as shown in FIG. 5E, among the empty slots scattered at that time in the area allocated by the DAMA method as the destination slot, the slot having the largest slot number is sequentially ordered. I will use it. In this way, the utilization status of the slots can be organized and the number of times the slots are moved can be reduced.

Mapping to slots on a satellite channel to effect the slot assignment move described above,
In the DAMA controllers 14 and 24 shown in FIG.
It has a table of all line allocation information according to both MA and PAMA methods, and when making a dynamic interrupt slot reservation by the PAMA method, where the target slot is already allocated by the DAMA method and is in use, where is that slot? It has a function to automatically determine whether to move.

When another line is assigned by the PAMA method to a slot to which a line is already assigned by the DAMA method by the above method, the slot reservation is dynamically made without disconnecting the communication of the already assigned line. Requires the slot assignment to be moved instantaneously while maintaining the synchronization of the frame on the satellite channel even while the slot channel assignment is being moved. The procedure for moving the slot allocation using the slot allocation change state identifier while maintaining synchronization will be described below.

First, when line allocation by the PAMA system is requested for a slot already in use by the DAMA system, the DAMA controllers 14, 24 shown in FIGS. 2 and 3 are used.
Is it possible to dynamically change the line assignment of the slot by checking whether there is an empty slot whose assignment by the DAMA method has already been released from all the assignment information of the slots on the satellite channels managed by them. Find out. Then, as shown in FIG. 5D, an empty slot B exists in the slot area assigned by the DAMA method, and the line assigned to slot A can be moved to slot B. If it is determined that it is possible, the slot allocation change status identifiers in the header fields of the source slot A and the destination slot B are changed from 0 to 1. This is the source slot A
Since the dynamic interrupt slot reservation request by the PAMA method has occurred in the destination slot B, the line allocation is set to be moving between the A and B slots. Therefore, the empty slot B of the moving destination is reserved by the line for moving the assignment, and thereafter, the assignment by the DAMA method to the slot B cannot be performed until the assignment movement is completed.

Further, slot A in the next frame in which the slot allocation change state identifier is changed from 0 to 1,
In B, the control information regarding the transfer of the line allocation is inserted into the data field 27 in which the normal data of FIG. 4 is stored. This control information is the source slot A
Is the slot number of the destination slot B, and the destination slot B is the slot number of the source slot A. This control information interrupts the flow of data on the line being communicated, but only the slots A and B in the frame immediately after the slot allocation change state identifier changes from 0 to 1 are inserted. Otherwise, the transmission data is inserted into the data field 27 as usual. Therefore, even if the line for allocating the slot A to the slot B is a voice line, the communicating side can continue the communication with little awareness of the temporary insertion of control information. . FIG. 6 shows the flow of information inserted in the frame on the satellite channel.

By the way, the receiving side receiving the data sequentially receives each piece of information regarding the line allocation movement from the slot A to the slot B. D on the receiving side
The AMA controller constantly monitors the slot allocation change status identifier. Since this slot allocation change status identifier is an identifier indicating the allocation movement status of the same slot in the next frame on the satellite channel, the DAMA controller on the receiving side which has received the change from 0 to 1 of this slot allocation change status identifier Recognizes that the line allocation is about to be moved between slots A and B. Then, the control information regarding the line allocation movement inserted in slot A and slot B in the next frame is received. Here, first, a response that the transfer request for the line allocation between the slots A and B is surely received is returned to the transmitting side. Then, based on the control information of the source slot A and the destination slot B received next, a table of all line allocation information of slots on the satellite channel managed by the DAMA controller on the receiving side is checked, and the slot A , B, a new table is created in response to a transfer request for circuit allocation. However, at this point, the newly created table is temporarily retained and the old table is still used.

Now, the transmitting side receives the reception response transmitted from the receiving side. As a result, DAMA on the sending side
The controller returns the slot allocation change state identifiers of slot A and slot B from 1 to 0 after a certain period of time. Further, similarly to the receiving side, a new table created in advance is used in response to a request to move the line allocation between slots A and B, and the line allocation information is switched from the old table. Therefore, from the next frame in which the slot allocation change state identifier is returned from 1 to 0, channel allocation to the slot on the satellite channel is performed based on this new table, so that the slot A to be moved from this point is allocated. The existing line is newly assigned to slot B and transmitted.

When the receiving side receives the change of the slot allocation change state identifier from 1 to 0, the receiving side DAM
The A controller discards the old table for the line allocation information for the slots on the satellite channels and switches to the new table created in advance. And
From the next frame in which the slot allocation change state identifier has changed from 1 to 0, the information inserted in the slot A is newly received in the movement destination slot B.

If the receiving side fails to receive the control information regarding the line allocation movement between the slots A and B,
Since the reception response is not transmitted to the transmission side, the transmission side will not be able to perform the new switching of the line information table forever. Therefore, sender D
The AMA controller has a timer, and if there is no reception response from the receiving side within a certain period of time, the receiving side inserts the control information regarding the slot allocation movement into the normal data flow again by the above procedure. Wait for the reception response of. Further, if there is no reception response from the receiving side even if the control information is retransmitted a certain number of times, the slot allocation change state identifier is returned from 1 to 0, and the line allocation movement between slots A and B is released.

[0031]

As described above, the present invention is applicable to DAMA.
Set the slot reservation order by DAMA method and PAMA method for each sub-slot in the method slot,
If the target subslot is already allocated in the DAMA method when the line allocation request is made in the MA method and the line is in use, another subslot that has already been released in the DAMA method allocation and is vacant What,
Since the line allocation is moved while maintaining the synchronization and another line is allocated to the target subslot to which the line is moved by the PAMA method, the communication of the line already allocated by the DAMA method is interrupted. Without
Create an empty slot that can be assigned by PAMA method,
The effect of enabling dynamic slot allocation during communication by the PAMA method is obtained.

The present invention also provides D for subslots.
The slot allocation for the AMA line is performed from the highest subslot number, and the slot allocation for the PAMA line is performed from the lowest subslot number.
When the target sub-slot to be assigned to the scheme is already assigned by the DAMA method, the lines of this target sub-slot are sequentially moved from the one with the highest sub-slot number to the empty sub-slot, and the moved target sub-slot is moved. By assigning a PAMA line to the
The allocation area by the MA method can always be used from the side with the lowest slot number in the left-justified order, and there is also an effect that the effective use of the slot can be achieved.

Further, a DAMA controller is provided in each of the central station and a plurality of peripheral stations which compose the satellite communication system, and these DAMA controllers have all the allocation information of the lines by the DAMA and PAMA systems on the satellite channel. The dynamic interrupt slot reservation described above can be realized.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a satellite communication system according to the present invention.

FIG. 2 is a block diagram of a central station.

FIG. 3 is a block diagram of a peripheral station.

FIG. 4 is a frame structure and slot structure diagram on a satellite channel.

FIG. 5 is a diagram showing a procedure of dynamic interrupt slot reservation in the PAMA method by moving slot allocation.

FIG. 6 is a diagram showing a flow of information inserted into a frame on a satellite channel in accordance with movement of slot allocation.

[Explanation of symbols]

 1 Central Station 2 Satellite 3 Peripheral Station 12 Receiver 13 Received Data Processor 14 DAMA Controller 15 Transmitted Data Processor 16 Multiplexer 17 Timing Signal Generator 18 Control Signal Generator 19 Transmitter 22 Receiver 23 Received Data Processor 24 DAMA Controller 25 Transmit Data processor 26 Frame synchronization unit 27 Retransmission control unit 29 Transmission unit

Claims (4)

[Claims] 1. A central station and a large number of peripheral stations are arranged in a star shape, and a plurality of peripheral stations jointly use one satellite channel for communication from the peripheral stations to the central station through satellites. A satellite communication system that uses the AA / TDMA system for communication, and uses a time-division multiplexing (TDM) system that uses a broadcast-type channel for communication from a central station to peripheral stations via satellites. In the satellite communication system in which a part of the slots by the AA / TDMA system is reserved as the DAMA system slot and the DAMA system and the PAMA system are used by the slot, the DAMA system for each sub-slot in the DAMA system slot is used. And the slot reservation order by the PAMA method is set, and the target sub-slot is already D when the line allocation request by the PAMA method occurs.
If the line is being allocated by the AMA method and the line is in use, the line allocation is moved to another subslot that has already been released due to the DAMA system allocation and is vacant while maintaining the synchronization. A dynamic interrupt slot reservation method according to the PAMA method, characterized in that another line is allocated to the moved target subslot according to the PAMA method. 2. A DAMA method line slot is assigned to a subslot from one side of the subslot number, and a PAMA method line slot is assigned from the other side of the subslot number. Claim that when already allocated by the DAMA method, the line of this target subslot is sequentially moved from one side of the subslot number to an empty subslot, and the line of the PAMA system is allocated to the moved target subslot. A dynamic interrupt slot reservation method based on the PAMA method of Item 1. 3. A DAMA line is assigned to a subslot from a slot with a high subslot number, and a PAMA line is assigned to a slot from a low subslot number. 3. The dynamic interrupt slot reservation method according to the PAMA method according to claim 2, wherein the higher numbered ones are sequentially moved to empty subslots. 4. The PAMA system according to claim 1, wherein DAMA controllers are provided in the central station and the peripheral stations, and the DAMA controllers have information on all allocations of lines according to DAMA and PAMA systems on a satellite channel. Dynamic interrupt slot reservation method by.