JPH01149532A - System for tdma satellite communication - Google Patents

Abstract

PURPOSE:To avoid a function centralization to a reference station and to form a circuit with high reliability by equipping each slave station with an initial acquisition controller to execute the transmission timing control of a transmission burst signal by means of a self-station distance measuring using a line assigning request burst. CONSTITUTION:An aloha control part 36 of a slave station discriminates whether a collision with the other slave stations occurs or not by reception-checking the line assigning request burst through a receiving burst processing part 31. As a result, when the collision is not generated, its own station distance-measuring part 34 executes an initial acquisition operation by the self-station distance measuring through the use of the line assigning request burst. On the other hand, a receiving station monitors the line assigning request burst, and when it recognizes that the destination is to its own house, the station prepares the reception of a data burst. A transmission timing generating part 35 sends the transmission timing to a transmission burst processing part 38 according to the control output of its own station distance-measuring part 34, and a transmission burst is transmitted. When a transmission station turns to send the transmission burst signal after a transmission synchronization is acquired, the data burst is opened after a prescribed burst signal is sent.

Description

[Detailed Description of the Invention] [Summary] TDMA that enables distributed control of call processing in slave stations
Regarding satellite communication systems, the TDMA frame is divided into multiple time slots, some of which are set for processing line allocation requests, with the aim of enabling distributed processing of line allocation control and transmission synchronization control in each slave station. Take the configuration,
Each slave station has an Aloha control means that performs line allocation request processing using slotted Aloha call origination control for the time slot set for line allocation request processing, and a predetermined data burst that is secured by this line allocation request. When the line allocation request burst is acquired, an initial acquisition system is provided for controlling the transmission timing of the transmission burst signal by measuring the distance of the own station using the line allocation request burst.

[Industrial application field]

The present invention relates to a TDMA satellite communication system that enables distributed control of call processing in slave stations.

In particular, the present invention relates to a TDMA satellite communication system in which a TDMA frame line allocation request is made using the slotted Aloha system and further initial acquisition processing is performed.

[Conventional technology]

Conventionally, in a satellite communication network based on the TDMA (time division multiple access) system, by adopting a centralized control system using a reference station, it has become possible to easily control the start-stop operations of all slave stations.

For example, this control is achieved by preparing slots for controlling the transmission synchronization state of each slave station and the state on the line side in the reference burst of the TDMA frame sent by the reference station, and by providing slots for controlling the transmission synchronization state of each slave station and the state on the line side. A slave station synchronization burst was also prepared to report various information to the station.

In other words, in conventional TDMA network control, such a TDMA frame configuration is adopted, and the reference station constantly monitors the synchronization bursts of all slave stations, and after centrally processing the obtained information, uses the reference burst to allocate a line to each slave station. and initial acquisition (transmission synchronization) control, all controlled centrally at the reference station.

[Problem that the invention seeks to solve]

However, with this conventional method, ■ frame usage efficiency decreases because it is necessary to provide a control line for each slave station, and ■ management information for all slave stations is concentrated in the base station, making the configuration of the base station complex and large-scale. There were problems such as the unavoidable advancement of operational technology.

In addition, T゛DMA enables distributed control in each slave station.
Processing of DMA system line allocation requests (burst collision avoidance processing, etc.) is complicated, and similar to the centralized control method of the reference station, it is necessary to prepare a dedicated slot for initial acquisition processing, making it difficult to improve frame usage efficiency. It was difficult. That is, although the distributed control method is easy to manage and allows flexible network construction, it is necessary to solve the problems described above.

An object of the present invention is to provide a TDMA satellite communication system in which line assignment control and synchronization control can be distributed and processed in each slave station.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention.

In the figure, a TDMA frame 11 is divided into a plurality of time slots, and some of the time slots (Aloha slots) are set for line allocation request processing.

Each slave station 13 includes an Aloha control means 15 and an initial acquisition control means 17.

The Aloha control means 15 issues a line allocation request burst to a time slot set for line allocation request processing, and performs line allocation request processing using call control based on the slotted Aloha method.

When a predetermined data burst is secured by this line allocation request, the initial acquisition control means 17 controls the transmission timing of the transmission burst signal by measuring the distance of the own station using this line allocation request burst.

[For production]

In the present invention, the Aloha control means 15 performs line allocation request processing using the slotted Aloha method in the time slot for line allocation request processing provided in the TDMA frame 11, thereby making it possible for all slave stations to operate simultaneously. becomes.

Furthermore, using this line allocation request burst, the initial acquisition control means 17 performs self-station distance measurement.
By controlling the transmission timing of the transmission burst signal, time slots for transmission synchronization control can be made unnecessary, and each slave station can perform distributed control of call processing without going through the reference station.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a diagram showing an example of a frame structure of a TDMA frame according to the present invention.

As shown in the figure, in this embodiment, a reference burst RB, equal length data bursts DB, DB, .

Following DBn, there is a time slot set for a line allocation request at the rear end of the TDMA frame, and each slave station makes a line allocation request for this time slot using the slotted Aloha method. Note that this time slot is referred to as an "Aloha slot" in this specification.

Here, to briefly explain the slotted Aloha method, it transmits a burst (in this case, a line allocation request burst) to an empty slot (in this case, an Aloha slot) at an arbitrary timing, and at the same time checks to receive the burst, and other stations If a collision is detected, retransmission is attempted after a random period of time, and the process is repeated until no collisions are detected.

That is, in the present invention, the Aloha slot provided in the TDMA frame is used to perform call origination control using the slotted Aloha method, and the line allocation request process is performed using the fact that one station is automatically selected. It has become. Therefore, it becomes easy for all slave stations to perform line assignment change control at the same timing.

Furthermore, in the present invention, in response to a line allocation request using an Aloha slot, a slave station that has become able to allocate its own line can perform initial acquisition by distance measurement using a line allocation request burst. This feature eliminates the need for a dedicated slot for this purpose, and allows the called station to prepare for line connection to a terrestrial network during this time.

FIG. 3 is a block diagram showing the main part configuration of the slave synchronization control section.

In the figure, the received burst signal is received by the received burst processing section 3.
1 and is input to the reception synchronization control section 32. The output of the reception synchronization control section 32 is input to the transmission timing generation section 35 via the reception timing generation section 33 and the local distance measurement section 34. The output of the reception timing generation section 33 is manually input to the reception burst processing section 31 and the Aloha control section 36.

The control signal output of the reception burst processing section 31 is input to the Aloha control section 36 and the line management section 37. A call request signal is input to the line management section 37, and an incoming call instruction signal is output. Further, the output of the line management section 37 is input to the Aloha control section 36, and the output of the Aloha control section 35 is input to the transmission burst processing section 3 along with the output of the transmission timing generation section 35.
8 is input.

The reception data output of the reception burst processing section 31 and the transmission data input of the transmission burst processing section 38 are connected to the terrestrial network connection device together with the call request signal and the call reception instruction signal.

The transmission burst signal is output from the transmission burst processing section 38, and is connected to the satellite line together with the reception burst signal via a modulation/demodulation device and the like.

FIG. 4 is a flowchart illustrating the line allocation request processing procedure according to the embodiment of the present invention.

The operation of the embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

When a call request is made to each slave station, the line management section 37
determines whether or not there is an empty data burst, depending on the reception burst state (the state of the unique word of the reference burst) in the reception burst processing unit 31.

If there is no free data burst, the call processing is immediately canceled, but if there is a free data burst, it is then determined whether the Aloha slot is currently in use. If the Aloha slot is in use, the process returns to determining whether there is a free data burst after a random time.

If it is found that the Aloha slot is unused (at least there is no line allocation request from another slave station at the moment), the Aloha slot is allocated to the Aloha slot via the Aloha control unit 36 based on the timing control of the reception timing generation unit 33. A line allocation request burst is launched.

That is, the calling station confirms that it can secure the required number of free data bursts (slotted allo method), and requests line allocation for its own station when no other slave station has made a line allocation request.

The Aloha control section 36 receives and checks the line allocation request burst via the reception burst processing section 31 to determine whether there has been a collision with another station.

Here, if a collision with another station is detected, the transmission of the line allocation request burst is stopped, and after a random time, the process returns to determining whether there is an empty data burst.

If there is no collision with another station, the local station ranging section 34 uses the line assignment request burst to perform initial acquisition operation by measuring the local station distance. The called station monitors this line allocation request burst, and if it recognizes that it is addressed to its own station, it prepares to receive the data burst.

The transmission timing generating section 35 sends the transmission timing to the transmission burst processing section 38 in accordance with the control output of the local distance measuring section 34 . The transmission burst processing unit 38 starts sending out the transmission burst signal according to this transmission timing. Note that the Aloha control unit 36 stops sending out the line allocation request burst.

When the calling station moves to transmitting a transmission burst signal after acquiring transmission synchronization, the series of procedures ends by releasing the data burst after transmitting a predetermined transmission burst signal without going through the control of the reference station.

In this way, the method of the present invention performs line allocation request processing using the slotted Aloha method, coexists with the TDMA method with high frame usage efficiency, and performs initial acquisition processing using line allocation request bursts, thereby achieving flexibility. It is possible to easily construct a TDMA network.

[Effects of the Invention] As described above, according to the present invention, line assignment control and synchronization control are distributed in each slave station, so it is possible to avoid concentration of functions on the reference station, and to achieve highly reliable T.
It becomes possible to construct a DMA network.

Furthermore, since the amount of information exchanged between the reference station and the slave station is reduced, the overhead within the TDMA frame is reduced, and an improvement in frame usage efficiency can be expected, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention. FIG. 2 is a diagram showing an example of the frame structure of a TDMA frame based on the present invention. FIG. 3 is a block diagram showing the main part structure of the slave synchronization control section. The figure is a flowchart illustrating a line allocation request processing procedure according to an embodiment of the present invention. In the figure, 11 is a TDMA frame, 13 is a slave station, 15 is an Aloha control means, 17 is an initial acquisition control means, 31 is a reception burst processing section, 32 is a reception synchronization control section, 33 is a reception timing generation section, and 34 is an autonomous 35 is a transmission timing generation section; 36 is an Aloha control section; 37 is a line management section; 38 is a transmission burst processing section.

Claims (1)

[Claims] A TDMA frame (11) is divided into a plurality of time slots, some of which are set for line allocation request processing, and each slave station (13) is configured to handle line allocation requests. Aloha control means (15) that performs line allocation request processing using slotted Aloha call origination control for a time slot set for request processing; and when a predetermined data burst is secured by this line allocation request. A TDMA satellite communication system characterized by comprising: initial acquisition control means (17) for controlling the transmission timing of the transmission burst signal by measuring the distance of the own station using the line allocation request burst.