KR20150134847A - Reference node multiplexing method for closed loop-back satellite Time Division Multiple Access communication network - Google Patents

Abstract

The present invention relates to a communications system technology and, more specifically, to a reference node multiplexing method for a satellite time division multiple access communications system, provided to multiplex a reference node in order to enable network management when the reference node is damaged or unusable.

Description

[0001] The present invention relates to a reference node multiplexing method for a closed loop loop satellite time division multiple access communication network,

The present invention relates to a communication system, and more particularly, to a reference node multiplexing scheme for a time division multiple access (OFDM) communication system, And a method for multiplexing the same.

The network synchronization scheme of the satellite communication system can be classified into a closed loop-back scheme and an open loop scheme. A closed loop loop is used for a network composed of a reference node and a general node, in which a reference node transmits a reference signal for initial network synchronization at predetermined time intervals, and each node receives the reference signal to acquire and / Or network synchronization. On the other hand, the open method is mainly used in a network using multiple beams in a way that synchronizes the absolute time and the propagation delay time difference between the transmitting station and the receiving station.

A Closed Loop Satellite Time Division Multiple Access (TDMA) communication system provides a reference signal (Reference Burst, RB) at a reference node so that all common nodes joining the network synchronize with the reference signal do. However, the existing network synchronization scheme can maintain the network for a short time when the reference node providing the reference signal is damaged or unavailable, but the network can not be maintained as the time synchronization between the network subscribers is changed.

Also, during the maintenance of the reference node, there is a disadvantage that the network synchronization process must be performed again after performing the role change so that the general node can serve as the reference node after the network is shut down.

1. Korean Patent Publication No. 10-2014-0048306 2. International Patent Application No. 2012-128446A1 3. Japanese Laid-Open Patent No. 2005-535188 4. Korean Patent No. 10-1162091

The present invention has been proposed in order to solve the problem according to the above background art, and it is an object of the present invention to provide a method and apparatus for preventing a reference node from losing its role in a closed-loop backbone satellite time division multiple access A method for multiplexing nodes is provided.

In order to accomplish the above-mentioned object, the present invention provides a base station for multiplexing a reference node for maintaining a network synchronization when a reference node loses its role in a closed-loop backbone satellite time division multiple access communication network, And provides a multiplexing method.

Wherein the reference node multiplexing method comprises:

A reference node multiplexing method for a closed loop loop satellite time division multiple access communication network comprising a first reference node, a satellite, and a plurality of general nodes,

A reference signal search step in which the first reference node, the satellite, and a plurality of general nodes search a reference signal for synchronization of the network;

A priority checking step of checking the priority among the plurality of general nodes if the reference signal is not searched; And

The general node of the plurality of general nodes receives the frame according to the identified priority, searches for the reference signal from the received frame, and switches the general node having the highest transmission priority to the second reference node And a switching step.

In addition, the reference node switching step includes: a step in which the corresponding general node waits for a corresponding frame; Searching for a reference signal from a corresponding frame received after waiting; And switching a role as a second reference node if the reference signal is not searched for and providing a reference signal to another common node among the plurality of general nodes.

In addition, the frame information may include modem header information for the plurality of general nodes.

At this time, the modem header information includes terminal identifier information indicating identifier information for distinguishing between the reference node and the general nodes, terminal priority information indicating a priority of the corresponding node, and information indicating that the corresponding node is a reference node or a general node And a reference signal reception / non-reception information indicating identification information for confirming reception of a reference signal in the corresponding frame.

In addition, the priority order may be preset and specified.

The role of the reference node or the general node among the terminal role information may be set at the time of designing the initial network.

In addition, even when the first reference node fails to provide a reference signal and the general node having the highest priority is transferred to the second reference node, the plurality of general nodes maintain synchronization.

In addition, the timing of providing the reference signal may be provided in the frame information after the role change to the reference node is performed.

According to the present invention, in a general closed loop backbone time division multiple access communication system, it is possible to maintain a network and maintain synchronization between nodes even if the reference node is damaged or unavailable.

As another effect of the present invention, in the case of a general technology, a process of re-entering a network after re-establishing a role of each node after terminating the network in the event of a failure of a reference node must be performed. Since such a re-synchronization process is not necessary, , And network maintenance can be maintained regardless of the role of the node.

1 is a conceptual diagram illustrating the operation of switching a reference node in the absence of a reference signal according to an embodiment of the present invention.
2 is a block diagram showing the configuration of the nodes shown in FIG.
3 is a flowchart illustrating a reference node diversification in the absence of a reference signal according to a priority order according to an embodiment of the present invention.
4 illustrates a modem frame structure according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

Hereinafter, a reference node multiplexing method for a closed loop backhaul time division multiple access communication network according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram illustrating the operation of switching a reference node in the absence of a reference signal according to an embodiment of the present invention. Referring to FIG. 1, a communication network 100 for operating reference node switching when a reference signal is absent includes a reference node 110, a plurality of general nodes 120 to 140, and a satellite 150, do.

The communication network 100 is a communication system of the satellite time division multiple access system, in particular, a communication system of a closed loop backbone time division multiple access system. In other words, closed loop loop method is used as network synchronous method. As described above, in the case of the closed feedback loop method, the reference node 110 and the first to third general nodes 120 to 140 are configured.

Here, the reference node 110 transmits a reference signal for initial network synchronization to the first general node 120 to the third general node 140 at predetermined time intervals. The first to third general nodes 120 to 140 receive the reference signal transmitted from the reference node 110 to acquire synchronization and / or maintain network synchronization.

The reference node 110 and the plurality of general nodes 120 to 140 share a transponder (not shown) of the satellite 150. Here, the transponder is a synthesized word of the transmitter and the transponder, and is a kind of relay device mounted on the satellite 150. [ That is, the transponder receives a signal from the reference node 110 and a plurality of general nodes 120 to 140, amplifies / frequency-converts the received signal, and retransmits the signal to the ground.

Transponders include two types of transponders: a single system that directly converts / amplifies the frequency of received radio waves to the frequency of the retransmission radio wave, and a dual system that converts the frequency of the received radio wave once to an intermediate frequency and then converts / amplifies it to a retransmission frequency . In general, a single method is used for satellites.

In the TDMA system, one reference node 110 and a plurality of general nodes 120 to 140 share a transponder of the satellite 150 to generate a reference burst and a traffic signal traffic burst. In general, a satellite transponder simply acts as a relay for transmitting a received signal regardless of network control.

However, when a failure and / or a failure occurs in the reference node 110, the reference node 100 can not provide a reference signal. In this case, general nodes 120 to 140 having high priority operate as reference nodes.

In other words, when the reference signal is not received during the preassigned observation frame period according to the priority, the first general node 120 having the priority of 1 changes its role as the reference node.

In this state, if the first general node 120, which is the first priority node, does not provide the reference signal in the predetermined frame, the second general node 130 of priority 2 changes its role as the reference node.

If the first general node 120 and the second general node 130, which are the first and second highest nodes, do not perform the role change, the third general node 140 of priority 3 changes its role as the reference node .

2 is a block diagram showing the configuration of the nodes shown in FIG. 2, the reference node 110 among the nodes 110, 120, 130, and 140 includes a controller 210, a memory 220, a wireless communication unit 230, a modem 240, and the like. Of course, the reference node 110 and other common nodes 120,130, 140 have a similar configuration. In general, nodes (110, 120, 130 and 140 in FIG. 1) are communication terminals, but are not limited thereto, and may be repeaters, base stations, and the like.

The control unit 210 multiplexes reference nodes so that the reference node can operate in a damaged or unavailable state. In addition, control signals and / or data are exchanged with the elements 220, 230, and 240 included in the node.

The memory 220 stores modem header information of a node subscribed to the network, adds data on the terminal identifier, terminal priority, terminal role, and reference signal reception to the modem header information, And stores a program, data, and the like that implements an algorithm for changing a general node to a reference node according to a priority in the case of failure.

The memory 220 may be a memory provided in the controller 210 or may be a separate memory. Accordingly, a flash memory (SSD), a hard disk drive, a flash memory, an electrically erasable programmable read-only memory (EEPROM), a static random access memory (SRAM), a ferro- Volatile memory such as a magnetic random access memory (MRAM) and / or a volatile memory such as a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), or a double date rate (SDRAM) .

The wireless communication unit 230 plays a role of transmitting / receiving a communication signal with the satellite 150. In particular, it serves to transmit the reference signal to the satellite 150 or to receive the reference signal from the satellite 150.

The modem 240 serves to connect the other nodes 120, 130, and 140 to the network. Of course, the modem 240 has unique identification information, which makes it possible to distinguish the nodes. Although the modem 240 is shown separately in FIG. 2, it may be configured in the wireless communication unit 230.

Before describing FIG. 3, the multiplexing scheme will be described. In the multiplexing scheme, nodes excluding the reference node in the communication system of the time division multiple access scheme observe a network synchronization reference signal (reference burst) If the reference signal is not transmitted, the other node performs the role of the reference node according to the predetermined priority.

In each node, information such as priority / node identifier is shared using the modem header information of each node subscribed to the network, and when it is judged that the reference signal is not received from the general node, A generic node changes its role to a reference node and provides a reference signal.

In this case, the normal nodes with priority 2 and 3 search the reference signal in the pre-allocated frame period. If there is no reference signal after the search, the role is converted to the reference node in each frame period, And the node is a reference node.

In order to maintain the network even during the period of checking and receiving the reference signal in the reference node switching, the satellite time division multiple access communication network should be able to guarantee the minimum network synchronization even in the absence of the reference signal.

To this end, the modem header information adds a terminal (indicating a node) identifier, a terminal priority, a terminal role, and data on whether or not a reference signal is received. Each terminal (i. E., Representing a node) is identified as a terminal identifier and given a predetermined terminal priority according to the operational concept.

Also, the role of the terminal identifies that the role of the corresponding terminal is a reference node or a general node when designing the initial network. The general node checks whether the reference signal has been received in the corresponding frame, and provides the reference signal to the reference node.

If the reference signal is not received in the frame based on the modem header information, the general node having priority 1 changes the role to the reference node, and then provides the reference signal in the frame after the role change. A diagram showing such a frame structure is shown in Fig. 4 will be described later.

In this case, the role of the terminal is changed from the normal node to the reference node in the modem header of the reference signal, and then the other general node can re-receive the reference signal, thereby maintaining the network synchronization.

3 is a flowchart illustrating a reference node diversification in the absence of a reference signal according to a priority order according to an embodiment of the present invention. Referring to FIG. 3, when the network starts operating, the nodes 110 to 140 search for a reference signal (RB) to complete the transmission / reception synchronization (steps S310, S320, and S330).

As a result of completion of the transmission / reception synchronization, it is determined whether the reference signal RB is absent (step S331). Further, whether or not there is a reference signal is checked for every frame.

As a result of the determination, if the reference signal is absent, the priority of the node is confirmed (step S333).

If the priority of the corresponding node is 1, it is switched to the reference node and a reference signal is provided (step S340).

If the priority of the corresponding node is 2, it searches the reference signal for a period of time during which the general node (priority first general node) having higher priority than itself has to provide the reference signal, (Steps S350 and S351).

As a result of the determination, if the reference signal is absent, the general node having the priority of 2 is switched to the reference node, and the reference signal is provided (step S353).

If the priority of the corresponding node is 3, the general node (priority first general node, second general node) having a higher priority than the node itself waits for a period of time to provide the reference signal, searches for the reference signal, RB) (step S360, step S361).

As a result of the determination, if the reference signal is absent, the general node having the priority of 3 is switched to the reference node and provides the reference signal (step S363).

If the priority of the corresponding node is N, it waits for a time period in which a general node (priority first general node, second general node ... priority N-1 general node) having higher priority than itself has to provide a reference signal Then, it is determined whether or not the reference signal RB is present (steps S370 and S371).

As a result of the determination, if the reference signal is absent, the general node having priority 3 is switched to the reference node, and the reference signal is provided (step S373).

In other words, if a high priority general node does not perform a role change, it changes its role according to the priority of each general node.

4 illustrates a modem frame structure according to an embodiment of the present invention. Referring to FIG. 4, one frame 400 includes information units such as reference signal 1 (401-1), terminal 1 (401-2), and terminal 2 (401-3).

The reference signal 1 information 401-1 includes modem header information 411 and a preamble 412.

The terminal 1 information 401-2 includes a header guard time 413, a preamble 414, a data 415 tail guard time 415, and the like. The data 415 is again composed of a modem header 420 and data 421.

In the modem header information 411 and 420, terminal identifier information 431 indicating identifier information for identifying a node in the modem header, terminal priority information 432 indicating a priority of the node, and whether the node is a reference node or a general node Terminal role information 433 indicating identifier information to be checked, reference signal reception / non-receipt information 444 indicating identifier information for confirming reception of a reference signal in the frame, and the like.

Data is included in a modem header of a network subscriber (reference signal and general node) whether it is a terminal (node) identifier, a terminal priority, a terminal role reference signal or the like so that information is assigned according to the role of each node (Reference node or general node), priority, and reception of a reference signal to other nodes when transmitting and receiving data by directly granting (receiving a reference signal).

100: communication network
110: Reference node
120,130,140: Normal node
210:
220: Memory
230:
240: modem

Claims (7)

A reference node multiplexing method for a closed loop loop satellite time division multiple access communication network comprising a first reference node, a satellite, and a plurality of general nodes,
A reference signal search step in which the first reference node, the satellite, and a plurality of general nodes search a reference signal for synchronization of the network;
A priority checking step of checking the priority among the plurality of general nodes if the reference signal is not searched; And
A switching step of the corresponding general node among the plurality of general nodes receiving the frame according to the identified priority and searching for a reference signal from the received frame to switch to a second reference node;
And a reference node multiplexing method for a closed loop loop satellite time division multiple access communication network.
The method according to claim 1,
Wherein the reference node switching step comprises:
The corresponding node waits for the frame;
Searching for a reference signal from a corresponding frame received after waiting; And
And if the reference signal is not searched for, switching to a second reference node and providing a reference signal to another common node among the plurality of common nodes, wherein the closed- A reference node multiplexing method for a multiple access communication network.
The method according to claim 1,
Wherein the frame information includes modem header information for the plurality of general nodes, the modem header information includes at least one of terminal identifier information indicating identification information for identifying the reference node and the plurality of general nodes, Terminal priority information indicating a node, terminal role information indicating identifier information for confirming that the node is a reference node or a general node, and reference signal reception information indicating identifier information for confirming whether a reference signal is received in the frame And a reference node multiplexing method for a closed loop loop satellite time division multiple access communication network.
The method of claim 3,
Wherein the priority is preset and designated. ≪ RTI ID = 0.0 > [10] < / RTI > The method of claim 3,
Wherein the role of the reference node or the general node in the terminal role information is set at the time of designing the initial network.
The method according to claim 1,
Characterized in that even if the first reference node fails the reference signal with the loss of function and the general node with the highest priority is switched to the second reference node, A reference node multiplexing method for a time division multiple access communication network.
3. The method of claim 2,
Wherein the time of providing the reference signal is provided in the frame information after the role change to the reference node is made.

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