KR102169583B1 - Method and system for constructing a communication frame based on TDMA(time division multiple access) in an Ad- hoc network - Google Patents

Abstract

In a method of configuring a communication frame based on Time Division Multiple Access (TDMA) in an ad-hoc network composed of an upper node and a plurality of lower nodes, a plurality of lower nodes are assigned to an upper node. Receives a result of scanning the radio environment status of frequency channels in the frame mute field included in each of the previous communication frames, determines available frequency channels among the frequency channels based on the scan result, and follows the available frequency channels. The frequency channel allocated to the beacon section is leapsed between the next communication frames by assigning to a beacon section included in each of the communication frames.

Description

Method and system for constructing a communication frame based on time division multiple access (TDMA) in an Ad-hoc network (Ad-hoc network) network}

The present disclosure relates to a method and system for configuring a communication frame based on TDMA in an ad hoc network.

In general, ad hoc networks autonomously form networks between mobile nodes without the aid of a fixed infrastructure. In order to configure an ad hoc network, media access control between nodes connecting to the network must be efficiently performed, and collisions between nodes must be minimized during data transmission. To this end, an algorithm such as USAP-MA (Unifying Slot Assignment Protocol-Multiple Access), which is a TDMA-based medium approach applicable to ad hoc networks, has been proposed.

However, such an algorithm cannot guarantee reliability in a personal combat system requiring reliability of data transmission, and there is a problem in that data transmission and reception cannot be performed smoothly in an environment in which jamming and interference signals exist.

To provide a method and system for configuring a communication frame based on Time Division Multiple Access (TDMA) in an ad-hoc network.

The technical problem to be achieved by this embodiment is not limited to the technical problems as described above, and other technical problems may be inferred from the following embodiments.

According to an aspect of the present disclosure, a method of configuring a communication frame based on Time Division Multiple Access (TDMA) in an ad-hoc network composed of an upper node and a plurality of lower nodes, the upper node Receiving, by the plurality of lower nodes, a result of scanning a radio environment state of frequency channels in a frame mute field included in each of a predetermined number of previous communication frames; Determining, by the upper node, usable frequency channels among the frequency channels based on the scan result; And performing, by the upper node, allocating the available frequency channels to a beacon section included in each of successive communication frames, and performing a hopping of a frequency channel allocated to the beacon section between the next communication frames. I can.

In addition, the beacon period may include a plurality of beacon slots, and in each of the plurality of beacon slots, each of the upper node and the plurality of lower nodes may transmit control data using the same frequency channel.

In addition, the hopping of the frequency channel allocated to the beacon period may be performed in a frame mute field of each of the next communication frames.

In addition, by allocating any one of the available frequency channels to each of a plurality of data slots included in each of the next communication frames, a frequency allocated to each of the plurality of data slots between the plurality of data slots Channel hopping can be performed.

In addition, in each of the plurality of data slots, data including at least one of audio data, video data, and specialized data may be transmitted using a frequency channel to which the upper node and the plurality of lower nodes are assigned.

Also, the hopping of the frequency channel allocated to each of the plurality of data slots may be performed in a mute field included in each of the plurality of data slots.

In addition, in the step of allocating to a beacon section included in each of the following communication frames, a preset frequency channel may be allocated to a beacon section included in each of predetermined communication frames corresponding to an initial time among the next communication frames. .

In addition, the predetermined communication frames may correspond to a preset number of communication frames.

According to another aspect, an ad-hoc network system using a communication frame based on Time Division Multiple Access (TDMA) includes a frame mute field included in each of a predetermined number of previous communication frames. ) A plurality of lower nodes for scanning radio environment states of frequency channels; And receiving the scan result from the plurality of lower nodes, determining available frequency channels among the frequency channels based on the scanned result, and including the available frequency channels in each of the following communication frames. It includes an upper node allocated to a beacon period, and a frequency channel allocated to each beacon period may be hopping between the next communication frames.

According to another aspect, it is possible to provide a computer-readable recording medium in which a program for executing the method of the first aspect on a computer is recorded.

1 is a block diagram illustrating an example of an ad-hoc network configuration.
2 is a diagram illustrating an example of a structure of a communication frame based on Time Division Multiple Access (TDMA).
3 is a diagram illustrating an example of a structure of a beacon slot of a communication frame.
4 is a diagram illustrating an example of a structure of a data slot of a communication frame.
5 is a diagram illustrating an example of a structure of a frame mute of a communication frame.
6 is a diagram for describing an example of a frequency channel update procedure.
7 is a diagram for describing an example of intelligent frequency hopping performed in a communication frame.
8 is a flowchart illustrating an example of a method of configuring a communication frame based on TDMA in an ad hoc network.

The terms used in the present embodiments have selected general terms that are currently widely used as possible while considering the functions in the present embodiments, but this varies depending on the intention or precedent of a technician engaged in the art, the emergence of new technologies, etc. I can. In addition, in certain cases, there are terms that are arbitrarily selected, and in this case, the meaning will be described in detail in the description of the corresponding embodiment. Therefore, the terms used in the present embodiments should be defined based on the meaning of the term and the contents of the present embodiments, not a simple name of the term.

In the descriptions of the embodiments, when a part is said to be connected to another part, this includes not only the case that it is directly connected, but also the case that it is electrically connected with another component interposed therebetween. . In addition, when a certain part includes a certain component, it means that other components may be further included, rather than excluding other components unless specifically stated to the contrary.

Terms such as "consist of" or "comprises" used in the present embodiments should not be interpreted as necessarily including all of the various components, or steps described in the specification, and some of the components or It should be construed that some steps may not be included, or may further include additional elements or steps.

The description of the following embodiments should not be construed as limiting the scope of the rights, and what those skilled in the art can easily infer should be construed as belonging to the scope of the embodiments. Hereinafter, embodiments for illustration only will be described in detail with reference to the accompanying drawings.

1 is a diagram for describing an example of an ad-hoc network system.

An ad-hoc network is a network that is autonomously configured between mobile nodes without the help of a fixed base network, giving the network autonomy and flexibility.

An ad-hoc network with a tree structure is a centralized network, and has the advantage of a simple network, but may have a disadvantage in that a lower node is disconnected when a transmission delay is large and a relay node leaves.

An ad-hoc network with a mesh structure is a distributed network, in which all nodes constituting the network are connected. Therefore, since all nodes are connected, there is an advantage in that transmission delay is small, but there may be a disadvantage in that overhead is large because the amount of control messages for maintaining the network is large.

In one embodiment, an ad hoc network system having a cluster-mesh structure in which the advantages of a tree structure and a mesh structure are combined may be disclosed.

1 is a diagram showing a multi-hop ad hoc network system in a cluster-mesh structure. Specifically, FIG. 1 is a diagram illustrating a 7-hop relay network system in a cluster-mesh structure.

Referring to FIG. 1, an ad hoc network system may include an upper node and a plurality of lower nodes.

The lower node is a general node and can be located at the end of the network configuration. For example, the lower node may be referred to as a leaf node (LN) as shown in FIG. 1. However, the lower node is not limited to the LN, and other types of nodes may correspond to the lower node.

Each of the lower nodes may scan radio environment states of frequency channels in a frame mute field included in each of a predetermined number of previous communication frames. The frame mute field may correspond to the last section of each communication frame, and lower nodes may scan states of frequency channels to be operated.

The upper node is a node that comprehensively manages the network, and may perform radio resource management, data relay, network management and control, and the like of connected lower nodes. For example, the upper node may be referred to as a primary cluster node (PCN) as shown in FIG. 1. However, the upper node is not limited to the PCN, and other types of nodes may correspond to the higher node.

The upper node receives the result of scanning the radio environment status of the frequency channels in the frame mute field included in each of the predetermined number of previous communication frames by a plurality of lower nodes, and can be used among the frequency channels based on the scan result. Frequency channels can be determined. In addition, by allocating usable frequency channels to a beacon section included in each of successive communication frames, the frequency channel allocated to the beacon section can be leap between next communication frames. The beacon period may include a plurality of beacon slots, and in each of the plurality of beacon slots, each of the nodes constituting the ad hoc network system may transmit control data using the same frequency channel.

Nodes constituting the ad hoc network system in FIG. 1 may further include a cluster node (hereinafter referred to as CN) and a disconnected node (hereinafter referred to as DN).

As a data relay node, the CN can relay voice, video and professional data as well as control data transmitted and received by the PCN and LN. DN may be a node that cannot access the network. The DN may be a node attempting to join the network or a node that has left the network due to poor communication.

In order to configure a cluster-mesh multi-hop ad-hoc network, nodes constituting the ad-hoc network must autonomously configure the network, and control information and status information must be periodically transmitted between nodes. Hereinafter, in FIG. 2, a structure of a communication frame for periodically transmitting control information and state information between nodes in a multi-hop ad hoc network having a cluster-mesh structure will be described.

FIG. 2 is a diagram for explaining an example of a structure of a communication frame based on Time Division Multiple Access.

FIG. 2 shows the structure of a communication frame based on Time Division Multiple Access (TDMA) when up to 8 nodes access an ad hoc network. In FIG. 2, each communication frame may have a length of 100 ms.

On the other hand, the maximum number of nodes that can access the ad hoc network and the length of the communication frame are not limited as described above. Accordingly, the structure of the communication frame is not limited to FIG. 2 and may have various structures.

Referring to FIG. 2, an arbitrary N-th communication frame 200 includes 8 beacon slots 210 for transmission of network control messages between nodes accessing an ad hoc network, and data slots for data transmission ( 220) (data slot) 234, a frame mute field 240 (frame mute field) may be composed of a mute field 230 (mute field) located at the end of each slot.

In the beacon slot 210, data related to network control, such as routing information, resource allocation information, topology information, frequency information, and encryption key information, may be transmitted and received. In the mute field 230 located between the beacon slots 210, the transmission/reception mode can be switched.

Data including at least one of audio, video, and professional data may be transmitted and received in the data slot 220. In the mute field 230 located between the data slots 220, frequency hopping may be performed to ensure data transmission reliability in case a jamming or interference signal exists.

In the frame mute field 240 located at the end of the N-th communication frame 200, a set of frequency channels to be operated may be scanned to measure characteristics of each frequency channel. Based on the scan result in the frame mute field 240, a set of frequency channels usable for frequency hopping performed in subsequent communication frames may be determined.

3 is a diagram illustrating an example of a structure of a beacon slot of a communication frame.

Referring to FIG. 3, beacon slots 210 included in an N-th communication frame 200 are shown. The beacon slot 210 may transmit and receive control data required for communication network management.

Specifically, in each beacon slot 210, only one of the nodes constituting the ad hoc network can transmit control data. In addition, the number of beacon slots 210 included in any N-th communication frame 200 may be the same as the number of nodes constituting an ad hoc network.

For example, if there are a total of 8 nodes connecting to the ad hoc network, the node ID 1 can transmit control data in beacon slot #1, and the ID 2 node can transmit control data in beacon slot #2. have. Similarly, in beacon slot #8, the node with ID 8 can transmit control data.

In this case, each of the nodes constituting the ad hoc network in the beacon slots 210 included in the N-th communication frame 200 may transmit control data using the same frequency channel.

On the other hand, each beacon slot 210 is an automatic gain control (Automatoic Gain Control, hereinafter referred to as AGC) field, a preamble (hereinafter referred to as PRMB) field, a cyclic prefix (hereinafter referred to as CP) field, pilot (Pilot) field, control It may be composed of a data (Control Data, hereinafter CTRL_Data) field and a mute field 230.

The AGC field is a reference signal transmission region for measuring the received signal strength, performs automatic gain control of the receiving node based on the received signal strength, and may have a size of 128 bits. The PRMB field is a signal transmission region for time synchronization between nodes for each frame, and may have a size of 256 bits. The CP field is an area for mitigating inter-symbol interference (ISI) between CTRL_Data fields in the beacon slot 210, and 56 bits of data at the end may be copied and placed in front of the filer field. The pilot field is a reference signal for estimating a state of a radio frequency channel and may have a total size of 64 bits. In the CTRL_ Data field, routing information (Routing Information Element, RIE), resource allocation information (Resource Alloscation Information Element, RAIE), network connectivity information (Network Connectivity Information Element, NCIE), frequency information (Frequency Set Information Element, FSIE) and encryption Data related to network control, such as key information (RSA Key Information Element, RKIE), may be transmitted and received. The CTRL_Data field may have a size of 140 bits, and in one beacon slot 210, four CTRL_Data fields may have a total size of 560 bits. Meanwhile, the size and number of fields constituting the beacon slot 210 are not limited to those described above.

In the RIE, information of a transmitting node, a node type, and radio communication quality information of an adjacent node may be transmitted. In the RAIE, resource allocation information is included by the PCN, which serves as an administrator in the network, and may be transmitted to each node constituting the ad hoc network. Information for data relay may be transmitted to the NCIE, and the PCN and CN may perform data relay and delivery using the corresponding information. The FSIE stores frequency channel scanning information in which each node constituting an ad hoc network scans the frequency channels to be operated and frequency channels available in subsequent communication frames successively by the PCN, and stores the beacon slot 210 and data slot. It can be used for the frequency hopping performed at 220. The RKIE may contain information of a key that encrypts data and may be transmitted. In the mute field 230, which is the last field of the beacon slot 210, transmission/reception switching of the beacon slot 210 may be performed, and may have a size of 40 usec. If it is the node's turn to transmit the control message, it may be switched to the transmission mode, and if it is not the turn to transmit, it may be switched to the reception mode to receive the control message of another node.

4 is a diagram illustrating an example of a structure of a data slot of a communication frame.

Referring to FIG. 4, data slots 220 included in an N-th communication frame 200 are illustrated.

Each data slot 220 may be composed of a cyclic prefix (CP) field, a pilot field, a data field, and a mute field 230.

In the data field of the data slot 220, electronic data including at least one of voice data, image data, and professional data may be transmitted and received. The roles of each of the CP field, pilot field, and mute field 230 are as described above with reference to FIG. 3.

Specifically, in each data slot 220, only one of the nodes constituting the ad-hoc network can transmit data. For example, in data slot #1 to data slot #10, a node with ID 1 can transmit data, and in data slot #210 through data slot #234, a node with ID 8 can transmit data.

In this case, a node that transmits data in each data slot 220 included in an N-th communication frame 200 may transmit data using any one of available frequency channels.

Therefore, since the frequency channel used for each data slot 220 in an arbitrary N-th communication frame may be different, the mute field 230 of the data slot 220 not only changes the transmission/reception mode but also performs a frequency channel leap. have.

Meanwhile, the size and number of fields constituting the data slot 220 are not limited to those described above.

5 is a diagram illustrating an example of a structure of a frame mute field of a communication frame.

Referring to FIG. 5, a frame mute field 240 included in an N-th communication frame 200 is illustrated.

The frame mute field 240 may be composed of a setting field and a scan field. In the setting field, each node constituting the ad-hoc network may set hardware for scanning the radio environment status of the frequency channels to be operated. The setting field may have a size of 125 usec. In the scan field, each node may perform a frequency channel scan of one of the operating target frequency channels for 60 usec in the scan field. The scan field may be located 4 times in the frame mute field 240, and thus, each node may perform a frequency channel scan 4 times in the frame mute field 240. A 40usec idle field may be positioned between the scan fields.

Meanwhile, the size and number of fields constituting the frame mute field 240 are not limited to those described above.

6 is a diagram for describing an example of a frequency channel update procedure.

6 illustrates a process in which frequency channels are updated to leap the frequency channel when a jamming signal is generated in an ad hoc network composed of four nodes. Among the four nodes, ID 1, ID 2, and ID 3 nodes correspond to LNs, and ID 4 nodes may correspond to PCNs.

All four nodes constituting the ad-hoc network may scan 20 radio channel environment characteristics of frequency channels to be operated for each frame mute field included in each of communication frames #1 to #5. As described above in FIG. 5, since each node can scan 4 frequency channels in one frame mute field, each of the nodes completes scanning for 20 frequency channels to be operated during a total of 5 communication frames. can do.

Based on the measurement of the frequency channels performed in the frame mute field of one communication frame, all LNs send the scan result (Scan Report, hereinafter Scan_RPT) including the analysis information on the availability of each frequency channel to the next communication frame. It can be put in the FSIE and delivered to the PCN. That is, the Scan_RPT of each LN performed in the frame mute field of communication frame #1 may be included in the FSIE of communication frame #2 and transmitted to the PCN. Finally, the Scan_RPT of each LN performed in the frame mute field of communication frame #5 may be included in the FSIE of communication frame #6 and transmitted to the PCN. Accordingly, in communication frame #6, transmission of the Scan Report for 20 frequency channels to be operated to the PCN can be completed.

Thereafter, in communication frame #7, the PCN may aggregate the availability analysis information for each frequency channel received from each LN, and determine the available frequency channels based on this. The PCN may store available frequency channel information (FREQ_CH_INF) and resource allocation information in the FSIE of the CTRL_Data field in the beacon slot of communication frame #7 and transmit it to each LN.

After the transmission is complete, frequency channel updates of all nodes constituting the ad hoc network in communication frame #8 are completed (Frequency Channel Update, FREQ_CH_Update), so that the available frequency channels in the communication frames following communication frame #8 can be determined. have.

7 is a diagram for describing an example of intelligent frequency hopping performed in a communication frame.

Referring to FIG. 7, intelligent frequency hopping may be performed in a beacon slot as well as a data slot. Through this, it is possible to ensure stable data transmission by performing a frequency hopping not only for voice, video, and electronic data, but also for control data transmission for network configuration.

During communication frames #1 to #10, as described above with reference to FIG. 6, a frequency channel update process for hopping of the frequency channel during communication frames #11 to #20 may be performed. That is, during communication frame #3 to communication frame #7, each node constituting the ad hoc network may complete scanning of 20 frequency channels to be operated.

Thereafter, in communication frame #8, transmission of the Scan Report for 20 frequency channels to be operated to the PCN can be completed, and in communication frame #9, frequency channel information (Frequency Channel Information, FREQ_CH_INF) and resources available to the PCN Allocation information can be transmitted to each LN. In communication frame #10, the frequency channel update is completed (Frequency Channel Update, FREQ_CH_Update), so that a frequency channel usable in communication frames #11 to #20 may be determined.

In the data slots and beacon slots included in each of communication frames #11 to #20, frequency hopping is performed using available frequency channels determined through a frequency update procedure in communication frames #3 to #10. I can.

First, in the case of a data slot, as described above in FIG. 4, any one node that transmits data in each data slot may transmit data using any one of available frequency channels.

Accordingly, the PCN can allocate any one of the available frequency channels to each of the data slots included in the communication frame #11 to the communication frame #20.

Accordingly, since the frequency channel used for each data slot may vary, a frequency channel leap between data slots may be performed. Specifically, a frequency channel hopping may be performed in the mute field of the data slot. The frequency hopping pattern of the data slot may be randomly determined by taking a communication frame index and a data slot index as arguments.

In the case of a beacon slot, each of the nodes constituting the ad hoc network in the beacon slots included in the same communication frame as described above in FIG. 3 may transmit control data using the same frequency channel.

Accordingly, one frequency channel is allocated to a beacon period including a plurality of beacon slots in one communication frame, so that each node can transmit control data using a corresponding frequency channel in each of the plurality of beacon slots.

For example, frequency channel #1 may be assigned to a beacon section included in communication frame #14, and frequency channel #2 may be assigned to beacon section included in communication frame #15. Finally, frequency channel 7 may be allocated to the beacon section included in communication frame #20.

Accordingly, in the case of a beacon slot, a frequency channel leap may be performed in units of communication frames, not in units of beacon slots. Specifically, frequency channel hopping may be performed in a frame mute field of each of the communication frames.

Meanwhile, by setting one of the frequency channel sets to be operated as a common control channel (CCC), the CCC can be assigned to a beacon period included in each of predetermined communication frames corresponding to the initial time. have. For example, in communication frames #11 to #20 of FIG. 7, frequency channel 0 corresponding to CCC may be allocated to communication frame #11, communication frame #12, and communication frame #13. CCC is one of a set of frequency channels to be operated and may correspond to a preset frequency channel.

As shown in FIG. 7, in the case of the beacon slot, frequency channels may be mapped in a total of 10 frames, that is, a period of 1 second, but the period in which the frequency channels are mapped is not limited thereto.

8 is a flowchart illustrating an example of a method of configuring a communication frame based on TDMA in an ad hoc network.

In step 810, the upper node may receive a result of scanning the radio environment state of the frequency channels in a frame mute field in which a plurality of lower nodes are included in each of a predetermined number of previous communication frames. The upper node is a node that comprehensively manages the network and can perform radio resource management, data relay, network management and control, and the like of lower nodes. The plurality of lower nodes may scan the state of the frequency channels to be operated.

In step 820, the upper node may determine available frequency channels among the frequency channels based on the scan result. The upper node may determine frequency channels that can be used in subsequent communication frames among frequency channels to be operated.

In step 830, frequency channels that can be used by an upper node may be allocated to a beacon period included in each of the following communication frames, and the frequency channel allocated to the beacon period may be leap between the next communication frames. The beacon period may include a plurality of beacon slots, and in each of the plurality of beacon slots, control data may be transmitted using the same frequency channel to which the upper node and the plurality of lower nodes are assigned.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed on a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. In addition, the data structure used in the above-described embodiment of the present invention can be recorded on a computer-readable recording medium through various means. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (eg, ROM, floppy disk, hard disk, etc.), and an optical reading medium (eg, CD-ROM, DVD, etc.).

So far, the present invention has been looked at around its preferred embodiments. Those of ordinary skill in the art to which the present invention pertains will be able to understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (10)

In a method of configuring a communication frame based on Time Division Multiple Access (TDMA) in an ad-hoc network composed of an upper node and a plurality of lower nodes,
Receiving, by the upper node, a result of scanning a radio environment state of frequency channels in a frame mute field included in each of a predetermined number of previous communication frames by the plurality of lower nodes;
Determining, by the upper node, usable frequency channels among the frequency channels based on the scan result; And
The upper node allocating the available frequency channels to a beacon section included in each of the following communication frames, and performing a hopping of the frequency channel assigned to the beacon section between the next communication frames,
The frame mute field,
A setting field through which the lower nodes can set hardware for scanning radio environment states of the frequency channels;
The method is composed of a scan field through which the lower nodes can scan the frequency channels. The method of claim 1,
The beacon section is
A method of including a plurality of beacon slots, and in each of the plurality of beacon slots, each of the upper node and the plurality of lower nodes transmit control data using the same frequency channel. The method of claim 1,
The hopping of the frequency channel allocated to the beacon period is performed in a frame mute field of each of the next communication frames. The method of claim 1,
By allocating any one of the available frequency channels to each of a plurality of data slots included in each of the next communication frames, the frequency channel allocated to each of the plurality of data slots between the plurality of data slots The method further comprising the step of performing a leap. The method of claim 4,
In each of the plurality of data slots, a method of transmitting data including at least one of audio data, video data, and professional data by using a frequency channel to which the upper node and the plurality of lower nodes are assigned. The method of claim 4,
The hopping of the frequency channel allocated to each of the plurality of data slots is
A method performed in a mute field included in each of the plurality of data slots. The method of claim 1,
The step of allocating, by the upper node, the available frequency channels to a beacon period included in each of the following communication frames,
A method of assigning a preset frequency channel to a beacon section included in each of predetermined communication frames corresponding to an initial time among the following communication frames. The method of claim 7,
The predetermined communication frames correspond to a preset number of communication frames. A computer-readable recording medium storing a program for executing the method of claim 1 on a computer. In an ad-hoc network system using a communication frame based on TDMA (Time Division Multiple Access),
A plurality of lower nodes for scanning radio environment states of frequency channels in a frame mute field included in each of a predetermined number of previous communication frames; And
A beacon that receives the scan results from the plurality of lower nodes, determines available frequency channels among the frequency channels based on the scan results, and includes the available frequency channels in each of the following communication frames Includes the upper node allocated to the interval,
Hopping of a frequency channel allocated to each of the beacon intervals between the next communication frames is performed,
The frame mute field,
A setting field through which the lower nodes can set hardware for scanning radio environment states of the frequency channels;
The system, wherein the lower nodes are configured with a scan field through which the frequency channels can be scanned.

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