KR102299524B1 - Method for distribured media access control in cognitive radio systems and apparatus for executing the method - Google Patents

Abstract

Disclosed are a method for controlling distributed media access in cognitive radio systems to minimize overhead due to spectrum sensing and an apparatus for executing the same. According to one embodiment of the present invention, the method for controlling distributed media access in cognitive radio systems is executed in a computing device including one or more processors and one or more programs executed on the one or more processors. The method comprises the following steps: detecting a signal for a channel of a wireless communication network; using a preamble included in the detected signal to determine whether the channel is used by a secondary user; using the level of the detected signal to determine whether the channel is used by a primary user; and performing competition for preemption of the channel according to whether the secondary user or the primary user uses the channel.

Description

Distributed media access control method in cognitive wireless communication system and apparatus for performing the same

Embodiments of the present invention relate to distributed medium access control technology in a cognitive wireless communication system.

Cognitive radio (CR) based on dynamic spectrum allocation is receiving great attention as one of the solutions to the problem of frequency resource shortage. In the cognitive wireless communication system, in a spectrum band allocated to a primary user, when a signal of the primary user does not exist, a secondary user performs communication in the corresponding spectrum band. Therefore, a spectrum sensing technique for accurately detecting the presence of a main user is a very important element in a cognitive wireless communication system.

On the other hand, in most of the spectrum sensing-based cognitive wireless communication, sub-users independently perform spectrum sensing at their location, and if there is no main user communicating around the sub-users, communication is performed.

However, since environments of sub-users performing communication, that is, a transmitting sub-user and a receiving sub-user may have different environments, there is a problem in that each of the sub-users must independently perform spectrum sensing.

Republic of Korea Patent Publication No. 10-1493240 (2015.02.09.)

Embodiments of the present invention are to provide a distributed medium control approach in a cognitive wireless communication system that minimizes the overhead due to spectrum sensing.

Distributed medium access control method in a cognitive wireless communication system according to an embodiment of the disclosure is performed in a computing device having one or more processors, and a memory for storing one or more programs executed by the one or more processors A distributed medium access control method comprising: sensing a signal for a channel in a wireless communication network; determining whether a secondary user uses a channel by using a preamble included in the sensed signal; determining whether a channel is used by a primary user using the level of the sensed signal; and performing competition for preemption of the channel according to whether the sub-user and the main user use the channel.

The distributed medium access control method may further include waiting for a preset time when it is determined that the channel is used by at least one of the sub-user and the main user.

The step of waiting for the preset time may include, when it is determined that the sub-user uses the channel, detecting a signal for the channel and waiting until the sub-user's data transmission is completed; and when it is determined that the main user uses the channel, stopping signal detection for the channel, waiting for the preset time, and resuming signal detection for the channel when the preset time elapses. may include.

Determining whether the sub-user uses the channel may include: calculating a similarity by comparing a preamble included in a signal sensed in the channel with a pre-stored preamble; and determining that the sub-user uses the channel when the similarity is greater than or equal to a preset reference value, and determining that the sub-user does not use the channel when the similarity is less than or equal to a preset reference value. have.

The step of determining whether the main user uses the channel may include calculating a level of a signal sensed in the channel; and determining that the main user uses the channel when the level of the signal is greater than or equal to a preset reference value, and determining that the main user does not use the channel when the level of the signal is less than or equal to a preset reference value may include.

Competing for preemption of the channel includes performing contention for preemption of the channel based on random backoff when it is determined that the channel is not used by the sub-user and the main user. , after performing contention for preemption of the channel, transmitting a ready-to-send (RTS) packet to a receiving sub-user who wants to transmit data when the channel is preempted; transmitting a data packet to the receiving sub-user when a clear-to-send (CTS) packet is returned from the receiving sub-user; and releasing an occupation of the channel when an ACK packet is returned from the receiving sub-user.

According to embodiments of the present invention, in the cognitive wireless communication system, the transmitting sub-user performs spectrum sensing and carrier wave sensing to detect the signal of the main user and the signal of the sub-users, thereby receiving the data transmitted by the transmitting sub-user. Communication can be performed without the sub-user performing separate signal detection.

1 is a block diagram illustrating and describing a computing environment including a computing device suitable for use in example embodiments;
2 is a flowchart illustrating a distributed medium access control method in a cognitive wireless communication system according to an embodiment of the present invention;
3 is a diagram illustrating a data transmission process according to a distributed medium access control method in a cognitive wireless communication system according to an embodiment of the present invention;
4 is a diagram for explaining a cognitive wireless communication system according to an embodiment of the present invention;

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to provide a comprehensive understanding of the methods, apparatus, and/or systems described herein. However, this is merely an example and the present invention is not limited thereto.

In describing the embodiments of the present invention, if it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification. The terminology used in the detailed description is for the purpose of describing embodiments of the present invention only, and should in no way be limiting. Unless explicitly used otherwise, expressions in the singular include the meaning of the plural. In this description, expressions such as “comprising” or “comprising” are intended to indicate certain features, numbers, steps, acts, elements, some or a combination thereof, one or more other than those described. It should not be construed to exclude the presence or possibility of other features, numbers, steps, acts, elements, or any part or combination thereof.

In the following description, the terms "transmission", "communication", "transmission", "reception" and other similar meanings of signals or information are not only directly transmitted from one component to another component, but also signal or information This includes passing through other components. In particular, "transmitting" or "transmitting" a signal or information to a component indicates the final destination of the signal or information and does not imply a direct destination. The same is true for "reception" of signals or information. In addition, in this specification, when two or more data or information are "related", it means that when one data (or information) is acquired, at least a part of other data (or information) can be acquired based thereon.

Also, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The above terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

1 is a block diagram illustrating and describing a computing environment 10 including a computing device suitable for use in example embodiments. In the illustrated embodiment, each component may have different functions and capabilities other than those described below, and may include additional components in addition to those described below.

The illustrated computing environment 10 includes a computing device 12 . In one embodiment, the computing device 12 may be a device for performing distributed media access control in the cognitive wireless communication system 100 according to an embodiment of the present invention.

Computing device 12 includes at least one processor 14 , computer readable storage medium 16 , and communication bus 18 . The processor 14 may cause the computing device 12 to operate in accordance with the exemplary embodiments discussed above. For example, the processor 14 may execute one or more programs stored in the computer-readable storage medium 16 . The one or more programs may include one or more computer-executable instructions that, when executed by the processor 14, configure the computing device 12 to perform operations in accordance with the exemplary embodiment. can be

Computer-readable storage medium 16 is configured to store computer-executable instructions or program code, program data, and/or other suitable form of information. The program 20 stored in the computer readable storage medium 16 includes a set of instructions executable by the processor 14 . In one embodiment, computer-readable storage medium 16 includes memory (volatile memory, such as random access memory, non-volatile memory, or a suitable combination thereof), one or more magnetic disk storage devices, optical disk storage devices, flash It may be memory devices, other forms of storage medium accessed by computing device 12 and capable of storing desired information, or a suitable combination thereof.

Communication bus 18 interconnects various other components of computing device 12 , including processor 14 and computer readable storage medium 16 .

Computing device 12 may also include one or more input/output interfaces 22 and one or more network communication interfaces 26 that provide interfaces for one or more input/output devices 24 . The input/output interface 22 and the network communication interface 26 are coupled to the communication bus 18 . Input/output device 24 may be coupled to other components of computing device 12 via input/output interface 22 . Exemplary input/output device 24 may include a pointing device (such as a mouse or trackpad), a keyboard, a touch input device (such as a touchpad or touchscreen), a voice or sound input device, various types of sensor devices, and/or imaging devices. input devices, and/or output devices such as display devices, printers, speakers and/or network cards. The exemplary input/output device 24 may be included in the computing device 12 as a component constituting the computing device 12 , and may be connected to the computing device 12 as a separate device distinct from the computing device 12 . may be

2 is a flowchart illustrating a distributed medium access control method in a cognitive wireless communication system according to an embodiment of the present invention. As described above, a distributed medium access control method in a cognitive wireless communication system according to an embodiment of the present invention includes one or more processors, and a memory for storing one or more programs executed by the one or more processors. may be performed on the computing device 12 . To this end, the distributed medium access control method in the cognitive wireless communication system may be implemented in the form of a program or software including one or more computer executable instructions and stored in the memory.

In addition, in the illustrated flowchart, the method is described by dividing the method into a plurality of steps, but at least some of the steps are performed in a different order, are performed in combination with other steps, are omitted, are performed in separate steps, or are shown One or more steps not included may be added and performed.

In step S202, the computing device 12 may detect a signal for the channel. Specifically, the computing device 12 may detect signals of users (primary users and secondary users) using a channel to perform data communication. Here, the channel may include a frequency range available for cognitive wireless communication in a wireless communication network.

In step S204 , the computing device 12 may determine whether the sub-user uses the channel by using a preamble included in a signal detected from the channel. Here, the preamble may be information for synchronizing transmission timing between two or more systems in network communication.

That is, since sub-users using the same channel follow the same communication standard, they use a similar preamble. Accordingly, sub-users can know each other's preamble.

Specifically, the computing device 12 may calculate the similarity by comparing the preamble included in the signal detected in the channel with the pre-stored preamble. When the calculated similarity is equal to or greater than a preset reference value, the computing device 12 may determine that the sub-user uses the channel. Also, when the calculated similarity is less than or equal to a preset reference value, the computing device 12 may determine that the sub-user does not use the channel. For example, the computing device 12 may perform carrier sensing for determining whether to use a channel by utilizing the characteristics of the preamble.

In step S 206 , the computing device 12 may determine whether the main user uses the channel by using the level of the signal detected in the channel.

That is, in cognitive wireless communication, the sub-user cannot check the communication standard of the main user having the exclusive right to use the corresponding channel. Accordingly, since the similarity of the preamble cannot be compared, it is possible to determine whether the main user uses the channel by using the level of the signal detected in the channel.

Specifically, when the level of the signal sensed in the channel is equal to or greater than a preset reference value, the computing device 12 may determine that the corresponding channel is used by the main user. Also, when the level of the signal sensed in the channel is less than or equal to a preset reference value, the computing device 12 may determine that the corresponding channel is not used by the main user. Here, the signal level may be the detected signal strength, and the preset reference value may be the signal strength when only noise is present. For example, the computing device 12 may perform spectrum sensing to determine whether to use a channel according to a signal detected from the channel.

In step S208, if it is determined that the channel is used (busy state), the computing device 12 may wait for a preset time. Specifically, if it is determined that the sub-user uses the channel, the computing device 12 may wait until the sub-user's data transmission is completed while maintaining signal detection for the corresponding channel. When the data transmission of the corresponding sub-user is completed, the computing device 12 may detect a signal for the corresponding channel again.

In addition, when it is determined that the main user uses the channel, the computing device 12 stops signal detection for the corresponding channel for a preset time (blocking time), and returns the corresponding channel when the preset time elapses. signal can be detected. Here, the blocking time is to prevent wasting power by detecting a signal until the communication of the corresponding main user is completed.

In step S 210 , if it is determined that the channel is not used (idle state), the computing device 12 may compete for preemption of the channel based on a random backoff. Here, the random backoff waits while decreasing the slot time as much as an allocated random number during the interval of the idle state of the channel, and when all the slot time is exhausted, access to the corresponding channel way to try Specifically, when it is determined that the channel is not used, the computing device 12 observes the channel while waiting for a randomly selected time after a predetermined time (distributed inter frame spacing (DIFS) time defined in the IEEE 802.11 standard) and waits for the selected wait If the channel remains idle for a period of time, the channel can be preempted. At this time, if it is confirmed that the channel is occupied during the selected waiting time, the backoff procedure may be performed again.

In step S 212 , the computing device 12 may transmit a ready-to-send (RTS) packet when the channel is preempted. Specifically, the computing device 12 may transmit the RTS packet to the sub-user who wants to transmit data.

In step S 214 , the computing device 12 may transmit a data packet when a clear-to-send (CTS) packet is returned from the sub-user receiving the RTS packet. Specifically, the computing device 12 may transmit the data packet when the sub-user who wants to transmit data receives the RTS packet and returns the CTS packet. Also, the computing device 12 may return an acknowledgment (ACK) packet in response to the sub-user receiving the data packet. At this time, if the CTS is not returned from the sub-user receiving the RTS packet within a preset time, the computing device 12 may determine that communication has failed and may not transmit the data packet. Meanwhile, the neighboring sub-users who have received at least one of the RTS packet and the CTS packet during the above process may set a Network Allocation Vector (NAV) and may not perform data transmission until the set NAV expires.

That is, the computing device 12 that wants to transmit data in the cognitive wireless communication system performs spectrum sensing and carrier wave sensing on signals of users (primary user and secondary user) using the channel. By sensing, the sub-user receiving the RTS packet transmitted by the computing device 12 may determine that there are no users using the corresponding channel. Accordingly, the sub-user (receiving sub-user) receiving the RTS packet can transmit the CTS packet and perform communication without performing separate signal detection.

3 is a diagram illustrating a data transmission process according to a distributed medium access control method in a cognitive wireless communication system according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a cognitive wireless communication system according to an embodiment of the present invention is a drawing for

3 and 4 , the main user system 200 may include a main user base station 210 and a main user terminal 220 , and the sub-user system 300 includes a sub-user base station 310 . and a sub-user terminal 320 .

The sub-user system 300 may recognize some or all of the frequency resources allocated to the main user system 200 as usable frequency resources using cognitive radio technology. In addition, the sub-user base station 310 and the sub-user terminal 320 belonging to the sub-user system 300 may transmit/receive data to each other using the recognized available frequency resources.

In this case, when the main user system 200 and the sub-user system 300 use the same frequency resource, a collision may occur between the main user system 200 and the sub-user system 300 . However, the main user system 200 has priority over the frequency resources allocated to the main user system 200 over the sub-user system 300 . Accordingly, the sub-user system 300 may use some or all of the frequency resources allocated to the main user system 200 with a limitation of not interfering with the communication operation of the main user system 200 . Accordingly, the sub-user base station 310 and the sub-user terminal 320 may sense a signal of the main user system 200 and perform data communication based on the sensing result.

The computing device 12 may include a sub-user base station 310 and a sub-user terminal 320 . Here, the sub-user terminal 320 transmitting data is referred to as a first sub-user SU1, and the sub-user terminal 320 receiving data is referred to as a second sub-user SU2. The first sub-user SU1 may determine whether a signal of a main user and a signal of a sub-user exist in a channel through spectrum sensing and carrier sensing. A method for analyzing spectrum sensing and carrier sensing is the same as the aforementioned distributed medium access control method.

The first sub-user SU1 may determine that the corresponding channel is in an idle state if there is no signal of the main user and the signal of the sub-users on the corresponding channel, and transmit the RTS packet to the second sub-user SU2. Upon receiving the RTS packet, the second sub-user SU2 may determine that there are no main users and sub-users using the corresponding channel and may return the CTS packet to the first sub-user SU1 . That is, the first sub-user SU1 determines whether the corresponding channel is being used by the main user and the sub-users, and transmits the RTS packet. When the second sub-user SU2 receives the RTS packet, the second sub-user Since (SU2) acquires information that there are no main users and sub-users using the corresponding channel, it is not necessary to perform separate signal detection for the corresponding channel. At this time, when there is a main user communicating with the second sub-user SU2 or there is a hidden node that the first sub-user SU2 cannot detect, the RTS packet reception fails. When the CTS packet is received, the first sub-user SU1 may transmit a data packet and may return an ACK packet from the second sub-user SU2 in response thereto.

Accordingly, in the distributed medium access control method in the cognitive wireless communication system according to an embodiment of the present invention, the first sub-user SU1 performs spectrum sensing and carrier wave sensing to detect the signal of the main user and the signal of the sub-users. , the second sub-user SU2 receiving the data transmitted by the first sub-user SU1 may perform communication without performing separate signal detection. Accordingly, since only one spectrum sensing is performed in the data communication process, overhead can be minimized.

Although representative embodiments of the present invention have been described in detail above, those of ordinary skill in the art will understand that various modifications are possible without departing from the scope of the present invention with respect to the above-described embodiments. . Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims described below as well as the claims and equivalents.

10: Computing Environment
12: computing device
14: Processor
16: computer readable storage medium
18: communication bus
20: Program
22: input/output interface
24: input/output device
26: network communication interface

Claims (15)

one or more processors, and
A distributed medium access control method performed in a computing device having a memory for storing one or more programs executed by the one or more processors, the method comprising:
detecting a signal for a channel of a wireless communication network;
determining whether a secondary user uses a channel by using a preamble included in the sensed signal;
determining whether a channel is used by a primary user using the level of the sensed signal; and
Competing for preemption of the channel according to whether the sub-user and the main user use the channel;
The distributed medium access control method comprises:
If it is determined that the channel is used by at least one of the sub-user and the main user, the method further comprising: waiting for a preset time;
The step of waiting for the preset time is,
When it is determined that the sub-user uses the channel, the signal for the channel is detected and the sub-user waits until the data transmission of the sub-user is completed, and when the data transmission of the sub-user is completed, the signal for the channel resuming sensing; and
When it is determined that the main user uses the channel, signal detection for the channel is stopped for a preset blocking time in order to prevent power wasted by detecting a signal until the main user's communication is completed. and re-sensing the signal for the channel when the preset blocking time has elapsed.
delete delete The method according to claim 1,
The step of determining whether the sub-user uses the channel includes:
calculating a similarity by comparing a preamble included in a signal detected in the channel with a pre-stored preamble; and
and determining that the sub-user uses the channel when the similarity is greater than or equal to a preset reference value, and determining that the sub-user does not use the channel when the similarity is less than or equal to a preset reference value. Media access control methods.
The method according to claim 1,
The step of determining whether the main user uses the channel comprises:
calculating a level of a signal sensed in the channel; and
When the level of the signal is greater than or equal to a preset reference value, determining that the main user uses the channel, and when the level of the signal is less than or equal to the preset reference value, determining that the main user does not use the channel Distributed media access control method comprising.
The method according to claim 1,
Competing for preemption of the channel comprises:
Competing for preemption of the channel based on random backoff when it is determined that the channel is not used by the sub-user and the main user;
After the step of performing competition for preemption of the channel,
transmitting a ready-to-send (RTS) packet to a receiving sub-user who wants to transmit data when the channel is preempted;
transmitting a data packet to the receiving sub-user when a clear-to-send (CTS) packet is returned from the receiving sub-user; and
When an ACK packet is returned from the receiving sub-user, the method further comprising the step of releasing the occupation of the channel.
one or more processors;
Memory; and
one or more programs;
wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors;
the one or more programs,
instructions for detecting a signal for a channel of a wireless communication network;
a command for determining whether a secondary user uses a channel by using a preamble included in the sensed signal;
a command for determining whether a primary user uses a channel using the detected signal level; and
and a command for performing competition for preemption of the channel according to whether the sub-user and the main user use the channel;
the one or more programs,
When it is determined that the channel is used by at least one of the sub-user and the main user, the method further includes a command for waiting for a preset time,
The command to wait for the preset time is,
When it is determined that the sub-user uses the channel, the signal for the channel is detected and the sub-user waits until the data transmission of the sub-user is completed, and when the data transmission of the sub-user is completed, the signal for the channel command to resume sensing; and
When it is determined that the main user uses the channel, signal detection for the channel is stopped for a preset blocking time in order to prevent power wasted by detecting a signal until the main user's communication is completed. and a command for re-sensing the signal for the channel when the preset blocking time has elapsed.
delete delete 8. The method of claim 7,
The command for determining whether the sub-user uses the channel is,
a command for calculating a similarity by comparing a preamble included in a signal sensed in the channel with a pre-stored preamble; and
and a command for determining that the sub-user uses the channel when the similarity is greater than or equal to a preset reference value, and determining that the sub-user does not use the channel when the similarity is less than or equal to a preset reference value, computing device.
8. The method of claim 7,
The command for determining whether the main user uses the channel is,
instructions for calculating a level of a sensed signal in the channel; and
Command for determining that the main user uses the channel when the level of the signal is greater than or equal to a preset reference value, and determines that the main user does not use the channel when the level of the signal is less than or equal to a preset reference value A computing device comprising a.
8. The method of claim 7,
The command for performing contention for preemption of the channel is:
and a command for performing contention for preemption of the channel based on random backoff when it is determined that the channel is not used by the sub-user and the main user;
the one or more programs,
a command for transmitting a ready-to-send (RTS) packet to a receiving sub-user who wants to transmit data when the channel is preempted;
a command for transmitting a data packet to the receiving sub-user when a clear-to-send (CTS) packet is returned from the receiving sub-user; and
The computing device further comprising an instruction for releasing the occupation of the channel upon replying an ACK packet from the receiving sub-user.
As a computer program stored in a non-transitory computer readable storage medium,
The computer program includes one or more instructions, which, when executed by a computing device having one or more processors, cause the computing device to:
detect a signal for a channel of a wireless communication network;
determining whether a secondary user uses a channel by using a preamble included in the sensed signal;
determining whether a primary user uses a channel using the detected signal level; and
Compete for preemption of the channel according to whether the sub-user and the main user use the channel;
The computer program causes the computing device to:
If it is determined that the channel is being used by at least one of the sub-user and the main user, wait for a preset time,
The computer program causes the computing device to wait for the preset time,
When it is determined that the sub-user uses the channel, the signal for the channel is detected and the sub-user waits until the data transmission of the sub-user is completed, and when the data transmission of the sub-user is completed, the signal for the channel resume sensing; and
When it is determined that the main user uses the channel, signal detection for the channel is stopped for a preset blocking time in order to prevent power wasted by detecting a signal until the main user's communication is completed. and a computer program stored in a non-transitory computer-readable storage medium for re-sensing a signal for the channel when the preset blocking time has elapsed.
delete delete

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