JPS63191423A - Satellite communication system - Google Patents

Abstract

PURPOSE:To utilize a line effectively and to reduce the price of a system by making a communication between alopha communication terminal equipments with slots which are provided with synchronizing means by using an alopha communication area with a slot. CONSTITUTION:A reservation system TDMA frame 1 is divided into a reservation system TDMA area 2 for groups which are high in calling frequency and the alopha communication area 3 with the slot for groups which are low in calling frequency, and terminal equipment in a group low in calling frequency makes a communication in the group by using alopha communication terminal equipment 4 with slots provided with synchronizing means 6 which generate operation area time slots based upon a control burst time slot 5 from a control office. Therefore, a group low in calling frequency makes a communication in an area assigned according to the calling frequency not by the reservation system, but by a random access communication system suitable to cases where the calling frequency is low and the group high in calling frequency performs a communication by the reservation system in a wide area assigned according to the calling frequency. Consequently, the line is utilized efficiently.

Description

[Detailed Description of the Invention] [Summary] Reservation method time division multiple access (hereinafter referred to as TDMA) frames are divided into reservation method ']' I) M A area and Aloha communication area, and stations with high call frequency are The group uses the reservation method TDMAiJ!!
Aloha communication with slots is used to communicate between C groups using the DMA area, and for station groups with low call frequency, a synchronization means is provided to create operational area time slots based on control burst time slots from the control station. Equipped with a terminal device and using the slotted Aloha communication area
By allowing communication to take place between groups, lines can be used effectively and the system is inexpensive.

[Industrial Application Field] The present invention relates to an improvement of a satellite communication system using a reservation type TDMA communication system.

The reservation type TDMA communication method means that when a transmission request occurs,
First of all, collisions are avoided by sending a reservation (e.g. 1 - rough hearth) to the control station, reserving the use of the channel, and transmitting packets in the reserved time slot. When there is a large amount of traffic, it is more efficient than random access transmission, and exhibits superior properties under medium to high loads.

To explain the slotted Aloha communication method, first, in the pure Aloha method, each station transmits packets completely randomly.

When a packet collision occurs, the transmitting station performs retransmission after setting a mutually independent random delay to avoid re-collision.

In this case, collisions occur due to partial formatting of the packets.

Therefore, in order to reduce the probability of collision, the slotted Aloha communication system transmits packets in time slots that are synchronized to a standard in common to all stations. Since no functions are required, it is cheaper than reservation type TDMA communication terminal equipment.

Note that random access methods, including this method, exhibit excellent properties under light loads.

If there is a group that communicates between stations with a high call frequency and a group that communicates between stations that make a low call frequency, when this is done using the satellite communication method, the call loss rate is low and the system is inexpensive. It is desirable that there be.

[Conventional technology]

A conventional example will be explained below using figures.

FIG. 4 is a diagram showing a conventional reservation method TDMA frame.
FIG. 5 is a block diagram of the main parts of an example of a reservation type TDMA communication terminal device.

In the conventional reservation-based TDMA system, even when a group that communicates with each other with a high frequency of calling and a group that communicates with each other with a low-frequency of calls participate, the reservation-based TDMA system cannot be used.
As shown in FIG. 4, the MA frame includes a control burst time slot 5. transmitted from a control station. It is assumed to be a normal type consisting of multiple traffic burst time slots for reservation and data time slots for transmitting and receiving data, and all participating stations use reservation type TDMA communication terminal equipment as explained below using Fig. 5. was used to communicate within the group.

The operation of the reservation type TDMA communication terminal device will be explained with reference to FIG.

The control burst receiver 20 receives the control signal from the control burst time slot 5 shown in FIG. Frame synchronization is performed to establish a receiving TDMA frame that takes into account the delay from the satellite's TDMA frame, and burst synchronization is established to establish a transmitting TDMA frame that takes into account the delay from the satellite's TDMA frame. Receiving section 28
．． Deke Hurst transmitter 25. The traffic burst transmitter 24 is notified.

Next, the trough ink burst transmitter 24 sends a reservation signal to the control station, and the control burst receiver 2 sends the control signal containing the notification of the time slot to be used from the control station.
0, the control information reception processing section 22 decodes the time slot to be used, and notifies the speed conversion buffer control section 27 via the line connection processing section 23, and also sends it via the traffic burst transmission section 24. Sends a confirmation signal that the information has been received to the control station.

Therefore, data of, for example, 64 Kbps sent from the terminal is stored in the transmission compression buffer 26, and under the control of the speed conversion buffer control unit 27, data of, for example, 25 M bps is stored at a time corresponding to the time slot used. The data burst transmitter 25 transmits the TDMA frame at the timing at which the transmission TDMA frame should be transmitted.

25 M b received by the data burst receiving unit 28
The received data of ps is inputted to the sofa 29 for reception decompression, expanded to 64 Kbps, and sent to the terminal.

In this way, all stations are grouped and T
Performs DMA communication.

[Problem that the invention seeks to solve]

However, since the reservation method is not a real-time fixed communication method, it is not always possible to secure a time slot for communication when desired to transmit, and in the satellite communication method, there is a delay in communication and a long turn round.

Therefore, even stations in a group with low calling frequency easily secure a data time slot for communication and continue to secure it even when they are not actually communicating, for example, for a period of 1].

For this reason, the line becomes full, and the call loss rate increases for stations in groups where calls are made frequently.

That is, there is a problem that the line usage efficiency deteriorates.

In addition, if a reservation-based TDMA communication terminal equipment is used at a station in a group that has a low calling frequency, it sends a traffic berth for reservation, determines the data time slot to be used, and transmits the data. For this purpose, the control information reception processing unit 222, line connection processing unit 23.1, and rough hearth I/transmission unit 24 shown in FIG. 5 are required, and there is a problem that the system becomes expensive.

Measures to solve problem C] FIG. 1 is a diagram showing the principle of the present invention.

A reservation type time division multiple access frame 1 is divided into a reservation type time division multiple access area 2 and an Aloha communication area 3 with a thrower I.

Synchronization means 6 for creating an operational area time slot in the slotted Aloha communication terminal device 4 based on the control Hurst time slot 5 from the reservation type time division multiple access control station.
will be established.

Aloha with a slot 7) in which communication is performed between the reserved time division multiple access communication terminal devices using the reserved time division multiple access area 2, and a synchronization means 6 is provided using the slotted Aloha communication area 3. Communicate between communication terminal devices.

[Effect]

According to the present invention, reservation scheme T' DMA frame 1
Reservation method for groups with high calling frequency 1' l) M
Divided into Area A 2 and Aloha Communication Area 3 with Scotto for groups with low call frequency according to call frequency, terminal equipment of groups with low call frequency receive control bursts from the control station. Communication is performed within the group using a slot-ready Aloha communication terminal device 4 provided with a synchronization means 6 for creating an operating area time slot based on a time slot 5.

Therefore, a group with a low call frequency will communicate in an area allocated according to the call frequency, using a random access communication method suitable for cases where the call frequency is low, rather than a reservation method.
Groups with high calling frequency communicate on a reserved basis in a wide area allocated according to the frequency of calling, so even though stations in groups with low calling frequency are not communicating, There is no need to secure a line, and the line can be used effectively.

Also, groups that make fewer calls use a slotted Aloha communication terminal equipment equipped with an inexpensive synchronization means 6.
The system is inexpensive.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a diagram showing the usage area of the reservation system TD MA frame according to the embodiment of the present invention, and FIG. 3 is a block diagram of the main parts of the slotted Aloha communication terminal equipment according to the embodiment of the present invention.

In the case of the present invention, as shown in FIG.
The MA frame 1 is divided into a reservation type TDMA area 2 for groups with high calling frequency and a thrower for groups with low calling frequency according to the calling frequency]・Iki Aloha communication area 3
Divide into.

Therefore, using the reservation type TDMA area 2, groups with high calling frequency can communicate between groups using the reservation type TDMA communication terminal equipment in the same manner as explained in the conventional example. I do.

For groups with low calling frequency, reservation method T I) M A
Using the Aloha communication terminal device 4 equipped with a slotter (thrower), which is equipped with a synchronization means 6 that creates an operational area time slot based on the control burst time slot from the communication control station, the communication is performed within the group using a random access method. communicate.

Here, the slotted Aloha communication terminal device according to the embodiment of the present invention will be explained with reference to FIG.

The control burst receiving unit 10 of the synchronization means 6 receives the control signal from the control burst time slot 5 shown in FIG. 2 from the control station, and the frame synchronization and burst synchronization unit 11 receives the control signal from the control burst time slot 5 as a reference to establish frame synchronization, establish a reception time slot, and notify the data burst reception section 12 and collision detection retransmission control section 16. Data burst synchronization is also established, and the transmission time slot is notified to the data burst transmission section 14.

When transmitting data, for example, data from a 64 Kbps terminal is stored in the waiting buffer 15, and when a call is desired to be made, it is sent to the data burst transmitting section 14 and transmitted under the control of the call detection waiting control section 17. Remember what you did.

The data burst transmitter 14 transmits data at, for example, 25 Kbps in a predetermined transmission time slot.

At this time, in order to detect a collision, the data burst receiver 1
2. Receive buffer 13. Transmission data is received via the collision detection and retransmission control section 16, and if a collision occurs, the transmission data is retransmitted under the control of the collision detection and retransmission control section 16.

Reception is performed by the data burst receiving unit 12 at 25p/i.
The data of b ps is received in the reception time slot and sent to the terminal via the reception buffer 13 as 64Kbps.

In this way, communication is performed using the random access method.

This slotted Aloha communication terminal device differs from the reservation type time division multiple access communication terminal device shown in FIG. The traffic burst transmitter 24 is not required and is inexpensive.

As mentioned above, there are fewer time slots allocated to groups that call less frequently, and since communication between groups is carried out using a random access method, time slots are secured for a long time even though there is little communication. There is no
The call loss rate in groups using the reservation type TDMA system where calls are made frequently is reduced, and lines can be used effectively.

Furthermore, groups that make fewer calls use slotted Aloha communication terminal equipment, which is cheaper than the reservation type TDMA communication terminal equipment described above, so that the cost of the system is low.

〔Effect of the invention〕

As explained in detail above, according to the present invention, lines can be used effectively and the cost of the system can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention. FIG. 2 is a diagram showing the usage area of the reserved TDMA frame according to the embodiment of the present invention. FIG. FIG. 4 is a diagram showing a conventional reservation method TDM&TE, and FIG. 5 is a block diagram of the main parts of an example reservation method TDMA communication terminal device. In the figure, 1 is a reservation type time division multiple access frame, 2 is a reservation type time division multiple access area, 3 is a slotted Aloha communication area, 4 is a slotted Aloha communication terminal equipment, 5 is a control burst time slot, / 4-piece plan #':y'bA-ronA@-Hoil'6 碍牌LKGrain Faculty Pro 72 Figure 5 Figure

Claims (1)

[Claims] A reservation type time division multiple access frame (1) is connected to a reservation type time division multiple access area (2) and an Aloha communication area (3).
The slotted Aloha communication terminal equipment (4) is provided with synchronization means (6) for creating operational area time slots based on the control burst time slots (5) from the reservation type time division multiple access control station. The reserved time division multiple access area (2) is used to perform communication between the reserved time division multiple access communication terminal devices, and the Aloha communication area (3) is used to perform the output of the synchronization means (6). A satellite communication system characterized in that communication between slotted Aloha communication terminal devices is carried out using the .