KR102208677B1 - Network synchronization apparatus and method of tdma based mesh network satellite communication system - Google Patents

Abstract

A network synchronization apparatus and method for a TDMA-based mesh network satellite communication system are disclosed.
In a satellite communication system, a network synchronization method of a terminal includes: receiving timing error information from a central station; Generating SST' (Superframe Start Time) every hour by reversely changing the sign of the timing error information; And receiving the traffic information transmitted by the transmitting terminal using the hourly SST'.

Description

Network synchronization device and method of TDMA-based mesh network satellite communication system {NETWORK SYNCHRONIZATION APPARATUS AND METHOD OF TDMA BASED MESH NETWORK SATELLITE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for controlling network synchronization between terminals in a TDMA-based mesh network satellite communication system.

The satellite communication network is composed of a satellite body, a central station, and a plurality of terminals, and can provide various multimedia services such as voice, video, and data to users. In the satellite communication network, a star network for communication between a central station and terminals and a mesh network for direct communication between terminals are constructed.

At this time, in order to operate the mesh network in the satellite communication network, each terminal included in the satellite communication system has a central station and timing and frequency. It can have a motive star net structure. And, the central station corrects the delay error between each of the terminals and the satellite. Accordingly, there is a limitation that the terminal performing mesh network communication must be within a distance that can be included in the error range, which is a range in which the delay error can be corrected by the central station.

Accordingly, there is a demand for a method of providing network synchronization between terminals without limitation of distance in a TDMA-based mesh network satellite communication network.

The present invention can provide an apparatus and method for providing network synchronization between terminals in a TDMA-based mesh network satellite communication network.

In a satellite communication system according to an embodiment of the present invention, a network synchronization method of a terminal includes: receiving timing error information from a central station; Generating SST' (Superframe Start Time) every hour by reversely changing the sign of the timing error information; And receiving the traffic information transmitted by the transmitting terminal using the hourly SST'.

In a satellite communication system according to an embodiment of the present invention, a method for synchronizing a network of a terminal includes: receiving Forward Link Signaling (FLS) and transmission delay information from the central station; Generating a Superframe Start Time (SST) using configuration information for each of a superframe, a frame, and a burst received through the FLS; Transmitting a logon burst (LB: Log-on Burst) signal to the central station at a transmission time determined according to the SST and transmission delay information, wherein the timing error information is obtained from the central station by using the logon burst signal. Can be calculated.

In the satellite communication system according to an embodiment of the present invention, the generating of an hourly SST' of the network synchronization method of the terminal includes an hourly SST by adding the transmission delay difference of the terminal B included in the timing error information to the SST. Can be generated.

In the satellite communication system according to an embodiment of the present invention, the traffic information of the network synchronization method of the terminal is transmitted at a transmission time determined by using the timing error information received from the central station by the transmitting terminal and SST (Superframe Start Time). It can be transmitted from the terminal.

A satellite communication system according to an embodiment of the present invention receives timing error information from a central station, reverses the sign of the timing error information to generate SST' (Superframe Start Time) every hour, and transmits using the hourly SST'. It may include a terminal B that receives the traffic information transmitted by the terminal.

Terminal B of the satellite communication system according to an embodiment of the present invention receives forward link signaling (FLS) and transmission delay information from the central station, and receives a superframe, a frame, and a burst from the FLS. Generates SST (Superframe Start Time) using configuration information for each of (Burst), and transmits a Log-on Burst (LB) signal to the central station at a transmission time determined according to the SST and transmission delay information. And, the timing error information may be calculated using the logon burst signal in the central station.

Terminal B of the satellite communication system according to an embodiment of the present invention may generate an hourly SST' by adding the difference in transmission delay of the terminal B included in the timing error information to the SST.

Traffic information of a satellite communication system according to an embodiment of the present invention may be transmitted from the transmitting terminal at a transmission time determined by using timing error information received from the central station and superframe start time (SST) by the transmitting terminal. .

According to an embodiment of the present invention, the terminal B generates a mesh SST' by reversely changing the sign of the timing error information, and receives the traffic information transmitted by the transmitting terminal using the mesh SST, Network synchronization between terminals can be provided without a device.

1 is a diagram illustrating a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.
2 is an example of communication between terminals in a conventional TDMA-based mesh network satellite communication system.
3 is a diagram illustrating a network synchronization method of a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.
4 is an example of a network synchronization process in a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The network synchronization method of the TDMA-based mesh network satellite communication system according to an embodiment of the present invention may be performed by the terminal A or the terminal B, which is a network synchronization device of the TDMA-based mesh network satellite communication system.

1 is a diagram illustrating a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.

The TDMA-based mesh network satellite communication system may include a central station 110, a terminal A 120, and a terminal B 130, as shown in FIG. 1.

The central station 110 may include a system control function capable of performing connection control and network resource management for access to a TDMA mesh network between the central station 110 and the terminal A 120 and terminal B 130.

Terminal A 120 may transmit a message requesting access to a TDMA mesh network between terminal B 130 and terminal A 120 to the central station 110. In this case, the central station 110 may transmit the received message to the terminal B 130, and may receive a response to the message from the terminal B 130 and transmit it to the terminal A 120. In addition, when the response to the message is connection acceptance, the central station 110 may transmit TBTP (Traffic Burst Time Plan) information to the terminal A 120. Further, the terminal A 120 may access the TDMA mesh network between the terminal B 130 and the terminal A 120 using the received TBTP information.

Terminal B 130 may receive a message requesting access to a TDMA mesh network between terminal B 130 and terminal A 120 from the central station 110. In addition, the terminal B 130 may transmit a response to the received message to the central station 110.

In addition, the terminal B 130 receives timing error information from the central station 110, reverses the sign of the timing error information to generate a mesh SST' (Superframe Start Time), and the transmitting terminal uses the mesh SST' Transmitted traffic information can be received.

Terminal B 130 is a terminal that performs communication with terminal A 130 at the request of terminal A 120 and may include the same functions as terminal A 120. That is, terminal B 130 and terminal A 120 are the same terminal, and may be classified according to whether a user of the terminal is a sender or a receiver.

In the TDMA-based mesh network satellite communication system according to an embodiment of the present invention, the terminal B 130 generates a mesh SST' by reversely changing the sign of the timing error information, and the transmitting terminal 120 uses the mesh SST'. By receiving the transmitted traffic information, network synchronization between terminals can be provided without an auxiliary device such as GPS.

2 is an example of communication between terminals in a conventional TDMA-based mesh network satellite communication system.

The DVB-RCS2 system TRF Burst Guard time may be K symbols regardless of SR. And, when the terminals operate at 1Msps, it is possible to connect a mesh network between terminals within a range of 10usec. In addition, by lowering the symbol rate, service coverage in which mesh network communication is possible can be widened. For example, when the SR is 0.5Msps, mesh network communication between terminals within the range of 20usec is possible.

In the case of communication between the terminal B 220 and the terminal A 210 in FIG. 2, the path difference between the terminal B 220 and the terminal A 210 may be 6 [usec]. Accordingly, in the case of transmission at 1 Msps, the path difference between the terminal B 220 and the terminal A 210 may be less than or equal to 10 usec, which is a guard time of 6 usec.

However, in the case of communication between the terminal B 220 and the terminal C 230, the path difference between the terminal B 220 and the terminal C 230 may be 26 [usec]. Accordingly, when the terminals operate at 0.25 Msps and increase the guard time to 30 usec or less, 26 usec, which is the path difference between the terminal B 220 and the terminal C 230, can be less than the guard time.

That is, in the case of 1Msps service, the distance from the ground between terminals must be within 3.47km to enable mesh network connection within 10[usec] guard time, and if within 11.5km range, mesh network connection within 20[usec] guard time It can be possible.

However, when the guard time is extended to connect a mesh network between terminals 100 km or more away, transmission efficiency may deteriorate.

3 is a diagram illustrating a network synchronization method of a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.

In step 310, the central station 110 may transmit Forward Link Signaling (FLS) information to the terminal A 120 and terminal B 130 for mesh communication, respectively. The central station 110 generates a Network Clock Reference (NCR) counter value using a stable internal clock (i.e. GPS), and generates a periodic Superframe Start Time (SST) based on this. At this time, SST is the NCR counter value. That is, the central station constructs a superframe, a frame, and a burst based on the NCR counter and transmits this information to the terminal through the FLS.

In addition, the terminal A 120 and the terminal B 130 respectively perform NCR (Network Clock Reference) recovery using data received from the central station to restore a clock synchronized with the central station, Activate the NCR counter.

In step 320, the terminal A 120 may receive configuration information for each of SST, superframe, frame, and burst through the FLS received in step 310, Terminal A 120 may transmit a Log-on Burst (LB) signal to the central station 110 at a transmission time determined according to SST and transmission delay information.

In step 325, terminal B 130 may receive configuration information for each of the SST, super frame, frame, and burst through the FLS received in step 310. Terminal B 130 may transmit the LB signal to the central station 110 at a transmission time determined according to the SST and transmission delay information.

In step 330, the central station 110 may estimate a timing error by demodulating the LB signal received in steps 320 and 325. And, the central station 110 may feed back the estimated timing error to the terminal A 120 and the terminal B 130, respectively.

In step 340, the terminal A 120 switches to a coarse sync state according to the timing error fed back in step 330, and transmits a control burst (CB) signal to the central station 110. have.

In step 345, the terminal B 130 may switch to a coarse sync state according to the timing error fed back in step 330, and transmit the CB signal to the central station 110.

In step 350, the central station 110 may generate timing error information by correcting the timing error estimated in step 330 with the CB signals received in step 340 and step 345.

In step 360, the central station 110 may transmit the timing error information generated in step 350 to terminal A 120 and terminal B 130, respectively.

In step 370, terminal A 120 may generate a mesh communication (terminal-to-terminal TDMA communication) SST' (Superframe Start Time) by changing the sign of the timing error information received in step 360 in reverse. In this case, the terminal A 120 may generate a mesh SST' by adding the difference in transmission delay of the terminal A 120 included in the timing error information to the SST.

In step 375, terminal B 130 may generate a mesh communication (terminal-to-terminal TDMA communication) SST' by changing the sign of the timing error information received in step 360 in reverse. In this case, the terminal B 130 may generate the mesh SST' by adding the transmission delay difference of the terminal B 130 included in the timing error information to the SST.

In step 380, the transmitting terminal 120 may determine a transmission time to transmit the timing error information received in step 360 and the traffic information determined using the SST to the terminal B 130.

In step 390, the transmitting terminal 120 may transmit traffic information to the terminal B 130 at the transmission time determined in step 380. In this case, the terminal B 130 may receive traffic information using the mesh SST' generated in step 375. Specifically, the terminal B 130 may estimate a scheduled time at which traffic information is to be received using'mesh SST'. In addition, terminal B 130 may receive traffic information transmitted at the estimated time.

4 is an example of a network synchronization process in a TDMA-based mesh network satellite communication system according to an embodiment of the present invention.

Terminal A (410) and terminal B (420) may each generate the SST (1000) using the FLS received from the central station (110).

In addition, terminal A 410 and terminal B 420 may transmit the LB to the central station 110 when the Tx time is 800 based on the transmission delay 200, respectively. In this case, the transmission delay 200 may be a delay value determined by estimating a transmission delay between the satellite and the terminal A 410 and the terminal B 420 as 100 since the transmission delay between the central station 110 and the satellite is 100.

At this time, since the transmission delay between the terminal A 410 and the satellite is 120, the central station 110 may receive the LB from the terminal A 410 at 1020. And, the central station 110 determines the difference between -20, which is the expected time to receive the LB from the terminal A (410), 1000 and the actual received time, 1020, as the timing error information between the terminal A (410) and the central station (110) can do.

Accordingly, the central station 110 may transmit the LB and the timing error information to the terminal A 410 at 1780 by reflecting the timing error information so that the terminal A 410 can receive the LB at the SST 2000.

At this time, the terminal A 410 may receive timing error information together with the LB. In addition, the terminal A 410 may determine the hourly SST' to 2020 by adding +20 in which the sign of -20, which is the timing error information, is reversed to the SST.

In addition, the terminal A 410 may transmit the LB to the terminal B 420 at 1780 in consideration of timing error information.

In addition, since the transmission delay between the terminal B 420 and the satellite is 110, the central station 110 may receive the LB from the terminal B 420 at 1010. In addition, the central station 110 determines -10, the difference between the expected time to receive the LB from the terminal B 420, 1000 and the actual received time 1010, as the timing error information between the terminal B 420 and the central station 110. can do.

Accordingly, the central station 110 may transmit the LB and timing error information to the terminal B 420 at 1790 by reflecting the timing error information so that the terminal B 420 can receive the LB to the SST 2000.

Terminal B 420 may receive timing error information together with the LB. In addition, the terminal B 420 may determine an hourly SST' to 2010 by adding +10 in which the sign of -10, which is timing error information, is reversed to the SST.

When the terminal A 410 is 1780, the LB transmitted to the terminal B 420 is transmitted to the terminal B in 2010 due to the transmission delay 120 between the terminal A 410 and the satellite and the transmission delay 110 between the terminal B 420 and the satellite. 420).

That is, the terminal B 420 may receive the RB transmitted by the terminal A 410 without delay by receiving the RB at a time corresponding to the hourly SST'.

In the present invention, the terminal B generates a mesh SST' by changing the sign of the timing error information in reverse, and receives the traffic information transmitted by the transmitting terminal using the mesh SST', so that the distance between the terminals increases, thereby increasing the transmission delay. Even so, since the terminal B can set the reception time according to the increased transmission delay, network synchronization between terminals can be provided without an auxiliary device such as GPS.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -A hardware device specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of the program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

As described above, although the present invention has been described by the limited embodiments and drawings, the present invention is not limited to the above embodiments, and various modifications and variations from these descriptions are those of ordinary skill in the field to which the present invention belongs. This is possible.

Therefore, the scope of the present invention is limited to the described embodiments and should not be defined, but should be defined by the claims to be described later as well as equivalents to the claims.

110: central station
120: terminal A
130: terminal B

Claims (8)

Receiving timing error information from a central station;
Generating SST' (Superframe Start Time) every hour by reversely changing the sign of the timing error information; And
Receiving the traffic information transmitted by the transmitting terminal using the hourly SST'
Synchronization method of a mesh network satellite communication system comprising a. The method of claim 1,
Receiving Forward Link Signaling (FLS) and transmission delay information from the central station;
Generating a Superframe Start Time (SST) using configuration information for each of a superframe, a frame, and a burst received through the FLS;
Transmitting a Log-on Burst (LB) signal to the central station at a transmission time determined according to the SST and transmission delay information
Including more,
The timing error information is
Synchronization method of a mesh network satellite communication system calculated by the central station using the logon burst signal. The method of claim 1,
The step of generating the hourly SST',
A method of synchronizing a mesh network satellite communication system in which the terminal B receiving timing error information from the central station adds the transmission delay difference of the terminal B included in the timing error information to the SST to generate an hourly SST' The method of claim 1,
The traffic information,
Synchronization method of a mesh network satellite communication system in which the transmitting terminal is transmitted from the transmitting terminal at a transmission time determined using timing error information received from the central station and a superframe start time (SST). Terminal B receiving timing error information from the central station, generating SST' (Superframe Start Time) every hour by changing the sign of the timing error information in reverse, and receiving traffic information transmitted by the transmitting terminal using the hourly SST'
Mesh network satellite communication system comprising a. The method of claim 5,
The terminal B,
Receives Forward Link Signaling (FLS) and transmission delay information from the central station, and Superframe Start (SST) using configuration information for each of the superframe, frame, and burst received by the FLS. Time), and transmits a Log-on Burst (LB) signal to the central station at a transmission time determined according to the SST and transmission delay information,
The timing error information is
A mesh network satellite communication system calculated by the central station using the logon burst signal. The method of claim 5,
The terminal B,
A mesh network satellite communication system for generating an hourly SST' by adding the transmission delay difference of the terminal B included in the timing error information to the SST. The method of claim 5,
The traffic information,
A mesh network satellite communication system in which the transmitting terminal is transmitted from the transmitting terminal at a transmission time determined using timing error information received from the central station and a superframe start time (SST).

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