JPH06112875A - Satellite line multiple access system - Google Patents

Abstract

PURPOSE:To obtain a multiple access system where a slot is allocated efficiently and impartially in the satellite line multiple address system using a slot dividing a time axis of a satellite repeater so as to connect among plural earth stations in multi-dimension. CONSTITUTION:Reservation data including a reservation number are sent from an earth station having a reservation request on same number of reservation use small slots corresponding to data slots. Upon the receipt of the reservation data, a data slot corresponding to a small slot over frames by number of reservation is used for a relevant earth station and the reservation data are shared in common by earth stations. Furthermore, the small slot is monitored and unreserved or untransmitted data are sent to an idle data slot not allocated to any earth station by the random access system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line connection system in a time division multiplex satellite communication network system sharing the same satellite repeater, and in particular, reserves data slot allocation control for data transmission to each earth station. The present invention relates to a satellite line connection method performed based on reservation data transmitted on a small slot for use.

[0002]

2. Description of the Related Art In general, multiple access communication in a satellite communication network system is one in which a plurality of earth stations share the same satellite repeater for communication, and in particular, multiple access based on a time division multiplex system. Communication (TDMA) is a method in which a frame composed of a plurality of slots is formed on a time axis of a shared satellite repeater, time-division-multiplexed, and the earth stations communicate with each other. This is to realize multi-dimensional data transmission / reception and slot reservation control between the respective earth stations by receiving all the radio waves transmitted from the other stations on the assigned slots by the respective earth stations.

Conventionally, the slot reservation method in such time division multiple access communication is roughly classified into the following 2
There were two ways. First, by adding slot reservation information to the transmission data and transmitting the data and reservation information at the same time based on a random access method, that is, a method that enables transmission from any earth station to a certain slot. This is a method of reserving slots.

FIG. 4 shows an example of this system.
One frame is sequentially configured on the time axis by the first to fifth slots. In the nth frame in the figure, the slot reservation information (reservation number 2) for new transmission data is added to the data to be transmitted, and the transmission data 41 is transmitted from the station A. Further, slot reservation information (reservation number 1) for new data is added to the data to be transmitted, and the transmission data 42 is transmitted from the B station. Accordingly, in each slot of the next (n + 1) th frame, the first and third slots are assigned to the station A,
Also, the second slot is assigned to station B. Therefore, in the (n + 1) th frame, station 43 transmits data 43 and 45 in the first and third slots, and station B transmits data 44 in the second slot.

Another method of slot reservation in multiple access communication is to reserve a data slot by providing a small slot for reservation in the frame. This is to send reservation data containing the number of data slots required for transmitting new data as a reservation number to a small slot as a reservation request by a random access method, and to send the data in the corresponding frame based on this reservation data. The slots are allocated until all the data slots are reserved or all the small slots are used. FIG. 5 shows an example of this method.
One frame is composed of a reservation small slot and first to sixth data slots in order on the time axis. In the reservation small slot of the n-th frame in the figure, reservation data 51 having a reservation number of 1 is transmitted from station A, reservation data 52 having a reservation number of 1 is transmitted from station B, and reservation data 53 having a reservation number of 2 is transmitted. Is transmitted from the C station, and the reservation data 54 having the reservation number 3 is transmitted from the D station.

Accordingly, in each slot of the next (n + 1) th frame, the first data slot is assigned to station A, the second data slot is assigned to station B, and the third and fifth data slots are assigned to station C. , And the fourth and sixth data slots are assigned to station D, respectively. Therefore, the n + th
Data 5 in the first data slot in one frame
6 is from station A, and data 57 is B in the second data slot.
From the station C, data 58 and 60 from the station C in the third and fifth data slots, and data 59 and 61 from the station C in the fourth and sixth data slots.
It is transmitted from each station. In this case, for the reservation number 3 requested by station D, only 2 slots are allocated in the (n + 1) th frame. Therefore, in order to reserve the remaining one slot for the subsequent frame again, the reservation data 55 having the reservation number 1 on the small slot of the (n + 1) th frame is newly transmitted from the D station.

[0007]

Accordingly, of the conventional methods, the method of adding the reservation information to the transmission data, such as the former method, does not require a small slot for reservation, which is the reason for this. The overhead does not reduce the transmission capacity. However, send data and reservation information
Since one data is transmitted in the same slot, collision (transmission contention), which is one of the drawbacks of the random access method, causes not only the transmission data but also the slot reservation information added to it to be lost. There was a problem that the loss due to

According to the latter method using a small slot for reservation, the empty data slots in the frame are sequentially allocated in response to a slot reservation request from each earth station, so that the use efficiency of the line is improved. Get higher However, there is a problem that if the traffic at a certain earth station is abnormally high, the line may be occupied by the earth station. The present invention minimizes the loss caused by a possible data collision, evenly allocates the data slot to each earth station, and effectively uses the empty data slot. The purpose is to provide a possible multiple access system for satellite circuits.

[0009]

In order to achieve such an object, the present invention has a frame including a plurality of data transmission data slots and the same number of reservation small slots corresponding thereto, In response to the generation of a data transmission request, the reservation of the data slot is requested by transmitting the reservation data including the number of data slots required for transmitting this data as the reservation number from the corresponding earth station onto the small slot. Then, in response to receiving the reservation data, over the frame corresponding to the reservation number, the same data slot corresponding to the small slot as the corresponding earth station,
This is a method of assigning the reservation data commonly to each of the earth stations. Further, by further monitoring this reservation small slot, it is determined whether or not the corresponding data slot is an empty slot which is not assigned to any earth station, and it is determined that this data slot is an empty slot. This is a method of permitting the transmission of the data to this empty slot when there is unreserved or untransmitted data in the local station.

[0010]

Therefore, the same data slot corresponding to the reserved small slot is assigned to the corresponding earth station over the number of reserved frames transmitted by the reserved small slot. Furthermore, if there is unreserved or untransmitted data, it is sequentially transmitted to empty data slots.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings by taking the case of four earth stations as an example. FIG. 1 shows an example of slot division and slot allocation of a satellite line according to the present invention. The horizontal axis represents the time axis, and indicates that transmission is sequentially performed from the (n-1) th frame to the (n + 2) th frame. Further, one frame is composed of four reserved small slots and the corresponding first to fourth data slots for data transmission, which are sequentially arranged on the time axis. There is. In the figure, data 11 to 13 are reserved for data slots,
This is the reservation data transmitted from each station to the small reservation slot, and includes the number of reservations. Also data 1
4 to 19 are transmission data transmitted on the data slot.

Next, the transmission of each data in the figure will be described step by step. First, in the (n-1) th frame, the data transmission request is generated at the A station, and subsequently, the data transmission request is generated at the B station and further at the C station. In order to reserve the data slot in response to these transmission requests, the reservation data is transmitted from each station to the small reservation slot in the next n-th frame. First, the required number of data slots is calculated from the data requested to be transmitted, and then the reserved data in which this is stored as the reserved number is transmitted from the corresponding earth station. Therefore, the reservation data 11 storing 2 as the reservation number is transmitted from the A station, and similarly, the reservation data 12 storing 1 as the reservation number is transmitted from the B station, and the reservation data 3 is stored from the C station in the same manner. Stored reservation data 1
3 are transmitted respectively. Further, the remaining earth stations have no data to be transmitted and do not transmit the reservation data in the nth frame. Regarding the processing at the time of transmission,
The details will be described later based on the transmission processing flowchart in the earth station of FIG.

Next, in each earth station that has received the reservation data in the reserved small slot in the nth frame, each data slot from the (n + 1) th frame onward is assigned to the corresponding earth station according to the number of reservations included in the reservation data. Assigned to This allocation method will be described later in detail based on the reception processing flowchart in the earth station in FIG.
It is omitted here. In Figure 1, the number of reservations from station A is 2
The first data slot corresponding to this small slot is allocated to the reservation data 11 having the above-mentioned information over the two frames from the (n + 1) th to the (n + 2) th frame, and for the reservation data 12 from the B station, this small slot is allocated. The third corresponding to
The data slot is allocated in the (n + 1) th frame, and further, for the reserved data 13 having the reservation number 3 from the C station, the fourth data slot corresponding to this small slot is the (n + 1) th to (n + 3) th frame. It has been shown that each has been assigned. Note that the n + th
Three frames are not shown.

Therefore, according to these allocations, data is transmitted from the corresponding earth station on each data slot of the (n + 1) th frame and thereafter. In the (n + 1) th frame, A
Station 14 transmits data 14 to the first data slot, station B transmits data 16 to the third data slot, and station C transmits data 17 to the fourth data slot. Further, in the (n + 2) th frame, station 18 transmits data 18 in the first data slot and station C transmits data 19 in the fourth data slot. Although not shown, station C transmits data in the fourth data slot of the (n + 3) th frame. Since the second data slot of the (n + 1) th frame is not reserved before the nth frame, the data 15 is transmitted by the random access method from the B station having unreserved or untransmitted data.

Next, the transmission processing procedure of each earth station will be described with reference to the flowchart of FIG. First, in step 20, in order to synchronize the data transmission with the timing of the transmission slot, the slot timing is detected, and it is determined in step 21 whether this slot is a data slot. If this slot is not a data slot but a reservation small slot, the process branches to step 22 and whether or not there is unreserved or untransmitted data in its own station, that is, whether or not a transmission request is newly generated. It is determined whether or not it has occurred, and if it has not occurred, the process returns to step 20.

If a transmission request is newly generated in the own station in step 22, a data slot reservation process for this transmission request is performed in steps after step 23. First, at step 23, the number of data slots required to transmit the data is calculated from the amount of the above-mentioned transmission data, and reservation data including this is created. Next, at step 24, a small reservation slot for transmitting this reservation data is selected. Here, a small slot for reservation corresponding to a data slot that has not been reserved in the next frame up to this point, that is, a data slot that is likely to be an empty data slot, is randomly selected, for example, by a predetermined procedure. It

In the following step 25, the number of reservations calculated in step 23, etc. are placed on the selected small reservation slot.
Information necessary for reserving a data slot is transmitted as reservation data. After sending the reservation data, the process is step 2
Return to 0. When the transmitted reservation data collides with the reservation data from another earth station and is lost, a small reservation slot is newly selected and transmitted again in the next frame.

If it is determined that the slot detected in step 21 is a data slot, the process proceeds to step 26, and it is determined whether or not this data slot is assigned to its own station. It Here, if this slot is assigned to the own station, the reserved corresponding data held in the own station is transmitted to this data slot in step 27. After the data transmission is completed, the process returns to step 20.

Further, when it is determined in step 26 that this data slot is not assigned to the own station, the transmission processing based on the random access method for the empty slot is performed in step 28 and subsequent steps. First, at step 28, it is judged whether or not this data slot is an empty slot which is not assigned to any earth station. This is judged based on the reservation status of the data slot at that time. Therefore, if it is determined that the data is assigned to any one of the earth stations, it is determined that the data cannot be transmitted because it is not an empty slot, and the process returns to step 20.

When it is determined in step 28 that this data slot is not assigned to any earth station and is an empty slot, in step 29, unreserved or untransmitted transmission in the own station is performed. It is determined whether or not there is data to be processed. If it is determined that such data is available, the process moves to step 27 and the corresponding data is transmitted on the above-mentioned empty slot. As a data slot allocation method, this is 1 per frame for the same earth station described later.
In order to improve the decrease in frame usage efficiency that can occur when only data slots are regulated, small reserved slots can be monitored and unreserved or untransmitted data within the local station can be transmitted if there are empty data slots. It is what

Therefore, since the random access method is used, that is, the data can be transmitted from any earth station, the data transmitted to the empty data slot collides with the data transmitted from other earth stations and is lost. If it happens, the reservation process is performed in the next frame at the time when the loss is found, and the frame is retransmitted. After the data transmission is completed, and when it is determined in step 29 that there is no data to be transmitted, the process returns to step 20.

Next, the receiving processing procedure of each earth station will be described with reference to the flowchart of FIG. First, in step 30, the data transmitted from any of the earth stations is received via the satellite repeater. Next, at step 31, it is judged whether or not this received data is the reservation data transmitted on the small reservation slot. If it is determined that the received data is not the reserved data but the transmitted data, the process proceeds to step 32, various receiving processes are performed, and the process returns to step 30.

If it is determined in step 31 that the received data is reserved data, the data slot reservation process is performed in step 33 and subsequent steps.
First, in step 33, it is judged whether or not this received data is transmitted from the own station. If it is determined that the reservation data is the reservation data of the own station, the process proceeds to step 34, and the reservation data is stored in the reservation small slot that has received the reservation data over the number of frames stored in the reservation data. The corresponding data slot is assigned to the own station.

That is, as in the data slot allocation situation of station A in FIG.
Therefore, when the reservation of two data slots is requested as the reservation number 2, the first data slot of the (n + 1) th frame corresponding to the corresponding small reservation slot and the same first slot of the (n + 2) th frame are requested to the A station. One data slot will be allocated. Therefore, according to this data slot reservation process, a plurality of data slots of the same earth station are not reserved in one frame, and one data slot is allocated per frame. If it is determined in step 33 of FIG. 3 that the reservation data does not belong to the own station, the process proceeds to step 35, and the frame corresponds to the number of reservations as in the case of the own station. Slots are allocated for other stations. These steps 34,
After the slot allocation based on the reservation data is completed in steps 35 and 35, the process returns to step 30.

[0025]

As is apparent from the above description, according to the present invention, a reservation small slot is provided in addition to a data slot to transmit reservation information and transmission data separately, and
The number of data slots that can be reserved is 1 for the same earth station.
One slot per frame, and monitoring the reserved data slots to enable transmission of unreserved or untransmitted data by random access method to empty data slots not reserved by any earth station. Is. Therefore, according to the present invention, it is possible to prevent loss of both reservation information and transmission data at the same time due to loss due to data collision, minimize the influence of data loss due to collision, and to prevent an earth station with higher traffic. This is remarkable in multiple access communication in a satellite communication network system, in which data slots can be evenly assigned to each earth station without occupying a satellite line, and the efficiency of use of frames can be improved. It is effective.

[Brief description of drawings]

FIG. 1 is a diagram showing slot division and slot allocation according to an embodiment of the present invention.

FIG. 2 is a transmission processing flowchart in the present invention.

FIG. 3 is a flowchart of a reception process in the present invention.

FIG. 4 is a diagram showing conventional slot division and slot allocation that does not use a reserved small slot.

FIG. 5 is a diagram showing conventional slot division and slot allocation using reservation small slots.

[Explanation of symbols]

11 A Reservation data transmitted from the earth station 12 B Reservation data transmitted from the earth station 13 C Reservation data transmitted from the earth station 14, 18 A Reserved transmission data transmitted from the A earth station 15 B From the earth station Unreserved transmission data transmitted 16 B Reserved transmission data transmitted from earth station 17, 19 C Reserved transmission data transmitted from earth station

Claims (2)

[Claims] 1. A frame consisting of a plurality of slots is formed on the time axis of a satellite repeater shared by a plurality of satellite communication earth stations, and the slots are assigned to each earth station, so that the repeater is provided. In the satellite circuit multiple access method for connecting multiple earth stations in multiple ways via a plurality of data transmission data slots and a corresponding number of small reservation slots, the data transmission request Reservation data containing the number of data slots required to transmit this data as a reservation number, depending on the occurrence,
Request a reservation for a data slot by transmitting on the small slot from the corresponding earth station, and in response to receiving this reservation data, transmit the same data slot corresponding to the small slot over a frame corresponding to the reserved number. A satellite circuit multiple access system characterized in that the reservation data is commonly allocated to the respective earth stations that have received the reservation data, as the corresponding earth station. 2. The satellite line multiple access system according to claim 1, wherein the reservation small slot is monitored to determine whether or not the corresponding data slot is an empty slot which is not allocated to any earth station. However, if it is determined that this data slot is an empty slot and there is unreserved or untransmitted data in the local station, the satellite is characterized by permitting the data transmission to this empty slot. Line multiple access method.