WO2020022592A1 - Method for improving packet transmission performance of second user in cognitive wireless network, and device therefor - Google Patents

Method for improving packet transmission performance of second user in cognitive wireless network, and device therefor Download PDF

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Publication number
WO2020022592A1
WO2020022592A1 PCT/KR2018/016876 KR2018016876W WO2020022592A1 WO 2020022592 A1 WO2020022592 A1 WO 2020022592A1 KR 2018016876 W KR2018016876 W KR 2018016876W WO 2020022592 A1 WO2020022592 A1 WO 2020022592A1
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user device
energy
probability
channel
secondary user
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PCT/KR2018/016876
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French (fr)
Korean (ko)
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신요안
오선애
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숭실대학교산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
    • H04W16/10—Dynamic resource partitioning
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the present invention relates to a method and apparatus for improving packet transmission performance of a secondary user (SU) having an ambient backscatter communication (AMBC) function in a cognitive radio (CR) network. .
  • SU secondary user
  • AMBC ambient backscatter communication
  • CR cognitive radio
  • Cognitive radio technology is a technology that can transmit and receive data even if there is no fixedly allocated channel, even if the channel assigned to the main user is not used in a specific time and region, for the communication of unauthorized secondary users (SU). to be.
  • the wireless cognitive technology includes an overlay technique and an underlay technique.
  • the underlay technique enables a cognitive communication network to simultaneously transmit data even at a frequency band in which the main user operates, but at a very low transmission rate.
  • the use of power allows the main user to have a very low level of interference so that communication is not interrupted.
  • the overlay technique is a technique in which the sub-user cannot transmit / receive data in the channel where the main user is communicating and utilizes only the channel without the main user.
  • Overlay-based cognitive radio networks can use the frequency band only after confirming that the primary user does not exist, whereas the primary user is not obliged to inform the cognitive radio network of its behavior, so that the secondary user of the cognitive radio network must The channel status must be continuously monitored at each time slot to determine whether the primary user has initiated transmission.
  • SU In this overlay-based cognitive wireless network, SU temporarily accesses an empty channel and transmits data, but when accessing a channel being used by a main user, SU gives up data transmission or goes to another channel to continuously access an empty channel. Move.
  • secondary users with Energy Harvesting (EH) access a channel that is empty and transmit data, and when the primary user accesses a channel that the primary user occupies, collects energy or temporarily disables the primary user. Access to transfer data.
  • EH Energy Harvesting
  • the secondary user cannot transmit data without an empty channel, which limits the improvement of data transmission performance of the secondary user.
  • the present invention is a secondary network in a cognitive radio network capable of improving packet transmission performance of a secondary user (SU) having an ambient backscatter communication (AMBC) function in a cognitive radio (CR) network.
  • An object of the present invention is to provide a method and apparatus for improving packet transmission performance of a user.
  • a method for improving packet transmission performance of a secondary user in a cognitive wireless network is a method for improving packet transmission performance of a secondary user device in a cognitive wireless network. Determining, by the secondary user device, the channel occupancy state of the primary user device by spectrum sensing; when the secondary user device approaches a channel occupied by the primary user device, backscattering is performed based on the energy level. Determining an operating mode of the mode or the energy collection mode, wherein the secondary user device operates according to the determined operating mode.
  • the energy occupancy of the channel may be determined by performing energy detection at a sampling frequency for a predetermined time at the start of the slot.
  • the determining of the operation mode may include calculating a backscattering probability according to the energy level, selecting a random value having a size between '0' and '1', and selecting the random value and the rear side. Comparing the scattering probability value, if the random value is less than the backscattering probability value may be determined as the backscattering mode, and if it is not less than the backscattering probability value may comprise the step of determining the energy collection mode.
  • the backscattering probability according to the energy level ( ) May be calculated by the following equation.
  • L is the energy maximum level
  • the operation may include transmitting a packet by reflecting an RF signal from the primary user device when the determined operation mode is a backscattering mode, and when the determined operation mode is an energy collection mode, Energy harvesting may be performed using the RF signal from the primary user device.
  • the secondary user device may transmit a packet by a wireless transmission method.
  • the secondary user device transmits a packet in a backscattering mode or a wireless transmission method
  • the packet transmission performance R may be defined by the following equation.
  • Silver energy level Probability of this occurring Is the channel sensing result in slot m, Is the channel occupancy state in slot m, Is the probability of transmitting a packet without collision with a primary user device through a wireless transmission method, Is the probability of sending a packet in backscattering mode, Is the probability of backscattering.
  • the probability that the energy level l will occur ( ) can be defined by the following equation considering the energy level transition probability.
  • Pc is the probability of consuming energy
  • Pd means the detection probability
  • the channel occupancy state of the primary user device is determined by spectrum sensing
  • the primary user A control unit for determining an operation mode of the backscattering mode or the energy collection mode based on the energy level when the channel occupied by the device is received from the primary user device when the operation mode determined by the control unit is the backscattering mode
  • Backscatter communication signal processing unit for transmitting the packet by using the reflection of the RF signal, the energy to perform energy harvesting using the RF signal from the primary user device when the operation mode determined by the control unit is the energy collection mode It includes a collector.
  • the method may further include a wireless communication signal processor for transmitting a packet by a wireless transmission method when a channel not occupied by the primary user device is accessed.
  • a wireless communication signal processor for transmitting a packet by a wireless transmission method when a channel not occupied by the primary user device is accessed.
  • the packet transmission performance of the secondary user can be improved by transmitting a packet to ambient backscatter communication (AMBC).
  • AMBC ambient backscatter communication
  • FIG. 1 is a diagram illustrating a cognitive radio network for improving packet transmission performance of a secondary user according to an embodiment of the present invention.
  • FIG. 2 is a diagram illustrating an operation of a secondary user device in a cognitive wireless network according to an embodiment of the present invention.
  • FIG. 3 is a diagram illustrating a method for improving packet transmission performance of a secondary user in a cognitive wireless network according to an embodiment of the present invention.
  • FIG. 4 is an exemplary diagram for explaining energy level dependent transmission of a secondary user device according to an embodiment of the present invention.
  • FIG. 5 is a diagram for describing an energy model of a secondary user device according to an exemplary embodiment.
  • FIG. 6 illustrates a channel model of a primary user device according to an embodiment of the present invention.
  • FIG. 7 is a view for explaining a secondary user device according to an embodiment of the present invention.
  • FIG. 8 is a channel state transition probability according to an embodiment of the present invention. Is a diagram illustrating packet transmission performance of a secondary user device that varies with time.
  • first, second, A, and B 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.
  • 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 present invention relates to a cognitive radio technology and a primary user, in which a secondary user device that has not been allocated a license band has an opportunity to access a channel and transmit data when a primary user device that uses a licensed band temporarily does not occupy a channel. It is based on wireless charging technology that collects energy by accessing the channel used by the device.
  • the primary user device described herein is the same term as the Primary User (PU), and the secondary user device is the same term as the Secondary User (SU).
  • PU Primary User
  • SU Secondary User
  • FIG. 1 is a diagram illustrating a cognitive wireless network for improving packet transmission performance of a secondary user according to an embodiment of the present invention
  • FIG. 2 is a diagram of a secondary user device in a cognitive wireless network according to an embodiment of the present invention. It is a figure for demonstrating operation
  • secondary user devices 200a, 200b in a cognitive wireless network for improving packet transmission performance of a secondary user according to an embodiment of the present invention, secondary user devices 200a, 200b,.
  • the channel is detected to determine whether the primary user occupies (uses) the channels allocated to the primary user device 100.
  • the wireless cognitive network is composed of a plurality of channels (ch1, ch2, ..., chn), the primary user device 100 uses a plurality of channels without interference from the secondary user device 200, 2
  • the primary user device 200 selectively uses a channel without disturbing the primary user device 100.
  • Each channel is divided into an occupied time and an idle time that the primary user device 100 uses.
  • the channel operates as an occupied channel during the time when the primary user device 100 uses the channel, and the channel operates as an unoccupied channel (empty channel) during the time when the primary user device 100 does not use the channel. .
  • the secondary user device 200 operates in the backscattering mode or the energy collection mode according to the energy level when the primary user device 100 approaches the channel occupied.
  • the backscattering mode means that the secondary user device EH-ST transmits a packet (data) by reflecting a signal received from the primary user device H-AP as shown in FIG.
  • Energy Harvesting (EH) mode uses the RF signal received from the primary user device (H-AP) by the secondary user device (EH-ST, SR) as an energy source, as shown in FIG. Say that.
  • the secondary user device accesses a channel that is not occupied by the primary user device
  • the secondary user device transmits the packet by the conventional wireless transmission method as shown in FIG. That is, the secondary user device (EH-ST) generates a signal and transmits the generated signal to another secondary user device SR through a wireless transmission method.
  • a secondary user device 200 transmits data or collects energy by reflecting a peripheral signal when approaching an occupied channel, and accesses data using an existing wireless transmission method when an empty channel is accessed. Will be sent.
  • FIG. 3 is a diagram illustrating a method for improving packet transmission performance of a secondary user in a cognitive wireless network according to an embodiment of the present invention
  • FIG. 4 is an energy level dependent transmission of a secondary user device according to an embodiment of the present invention.
  • 5 is a view for explaining an energy model of a secondary user device according to an embodiment of the present invention
  • Figure 6 is a channel model of the primary user device according to an embodiment of the present invention It is a figure for demonstrating.
  • the secondary user device determines the channel occupancy state of the primary user device by spectrum sensing (S310).
  • the sensing result is determined that the channel is occupied, but may actually be the first user device does not occupy the channel.
  • the sensing result it is determined that the channel is empty, but in practice, the primary user device may occupy the channel. Therefore, the secondary user device needs to calculate the false alarm probability and the detection probability by spectrum sensing.
  • the false alarm probability refers to a probability when the channel is determined to be occupied by the second user device but the primary user device does not occupy the channel.
  • the detection probability is determined when the channel is occupied by the sensing result of the secondary user device, and means a probability when the primary user device occupies the channel.
  • False alarm probability P f is defined as Equation 1 described below, and detection probability P d is defined as Equation 2 described below.
  • the signal and noise of the primary user equipment are both '0' which is the average, and the variance is , It is assumed to be a cyclic symmetric complex Gaussian signal.
  • the number of samples If is large enough, false alarm probability P f and detection probability P d are detection thresholds. It can be expressed by Equations 1 and 2 as follows.
  • C is the channel state of the primary user device
  • SNR signal-to-noise ratio
  • the secondary user device determines an operation mode of the backscattering mode or the energy collection mode based on the energy level. (S330). That is, the secondary user device determines whether to collect energy from the signal of the primary user device or transmit data by reflecting the signal from the primary user device when the primary user device approaches the channel being used. need.
  • the secondary user device checks its energy level (eg, battery remaining amount) and calculates backscattering probability according to the energy level.
  • Backscatter probability according to energy level ( ) Can be calculated using Equation 3 below.
  • L is the energy maximum level
  • the secondary user device determines that the accessed channel is occupied ( Determine the backscattering probability dependent on the energy level.
  • the secondary user device selects a random value having a size between 0 and 1, and compares the selected random value with the backscatter probability value. As a result of the comparison, if the random value is less than or equal to the backscattering probability value, the backscattering mode is determined.
  • the secondary user device preferentially performs energy collection when there is less energy stored, and preferentially performs backscattering mode over energy collection when more energy is held. That is, the secondary user device preferentially performs backscattering as the energy level is higher (Higher If the energy level is low, energy collection is preferentially performed (Higher ( )).
  • the secondary user device reflects the RF signal from the primary user device and transmits the packet (S340a). If the determined operation mode is the energy collection mode, from the primary user device Energy harvesting is performed using the RF signal (S340b).
  • the secondary user device may assume that '1' is transmitted by reflecting the RF signal from the primary user device, or '0' if it does not reflect the RF signal. As such, the secondary user device may transmit the packet via RF signal reflection from the primary user device.
  • the secondary user device collects RF signals from the primary user device to store energy. That is, the secondary user device uses the RF signal as an energy source.
  • step S320 If it is determined in step S320 that the secondary user device approaches an empty channel not occupied by the primary user (S350), the secondary user device transmits the packet by the conventional wireless transmission method (S370). In this case, transmitting the packet by the conventional wireless transmission means that the secondary user device generates and transmits a signal.
  • the secondary user device may transmit packets or collect energy when the primary user device approaches a channel occupied, and may collect energy when the primary user device accesses a channel not occupied.
  • a packet can be transmitted by the conventional wireless transmission method.
  • the secondary user device accesses the channel actually occupied and performs backscattering with a probability dependent on the energy level l, or has the energy necessary for data transmission as before ( ) Actually accessing an empty channel ( ) You can transfer data.
  • Equation 4 the packet transmission performance R of the secondary user device is expressed by Equation 4 below.
  • the energy level Be normal probability, Is the channel sensing result in slot m, May mean a channel occupancy state in the slot m.
  • Equation 4 the left item (Transmitting) refers to the case of performing backscattering when the data is accessed by accessing an empty channel. Further, in Equation 4, the probability that the energy level l of the secondary user device occurs ( ) Can be defined as Equation 5 below considering the energy transfer probability.
  • Pc is the probability of consuming energy
  • Pd is the probability of detection
  • the energy model may be as shown in FIG. To build an energy model, you need the probability of consuming energy, the probability of collecting energy, and the probability that the energy state will not change.
  • Equation 6 may be an equation for calculating the probability of consuming energy.
  • the secondary user device must collect energy without performing backscattering before the energy level of the secondary user device is transferred to a higher level. can do. Therefore, the probability of collecting energy may be defined as in Equation 7 below.
  • Equation 9 the probability that the energy state does not change may be defined as in Equation 9 below.
  • the channel state of the primary user device may be modeled as shown in FIG. 6.
  • Po channel state transition probability
  • an energy model can be constructed by calculating the probability that the secondary user device consumes energy, the probability of collecting energy, and the probability that the energy state does not change, and the steady state probability of generating an energy depletion state can be calculated from the energy model.
  • the secondary user device can improve packet transmission performance. That is, since the secondary user device preferentially performs backscattering rather than energy collection if sufficient energy is retained, it is possible to obtain higher packet transmission performance than performing backscattering with a static probability.
  • FIG. 7 is a view for explaining a secondary user device according to an embodiment of the present invention.
  • the secondary user device 200 may include an antenna 210, a controller 220, a wireless communication signal processor 230, a backscatter communication signal processor 240, and energy. And a collecting unit 250.
  • the controller 220 determines the channel occupancy state of the primary user device by spectrum sensing, controls the wireless communication signal processor 230 to operate when an unoccupied channel is accessed, and an energy level when the occupied channel is accessed. Based on the control of the backscatter communication signal processor 240 or the energy collector 250 to operate.
  • control unit 220 performs the energy detection at a sampling frequency for a predetermined time at the start of the slot to detect the sensing result ( Determine the occupancy state of the channel according to). At this time, , The channel is considered occupied, If so, it can be determined that the channel is empty.
  • the controller 220 controls the wireless communication signal processor 230 to operate when an unoccupied channel is approached. If the channel is not occupied, the controller 220 calculates the backscattering probability according to the energy level, and compares the backscattering probability with a value randomly selected from 0 to 1, so that the random value is the backscattering probability. When the value is less than the value, the backscatter communication signal processor 240 is controlled to operate. When the value is not less than the backscattered probability value, the energy collector 250 is controlled.
  • the wireless communication signal processor 230 generates an RF signal and transmits it through the antenna 210. At this time, the wireless communication signal processor 230 generates a signal by encoding according to the wireless communication technique used, and transmits the generated signal through the antenna 210.
  • the wireless communication technique may be various communication methods such as Bluetooth, Wi-Fi.
  • the wireless communication signal processor 230 Since the wireless communication signal processor 230 generates a signal and transmits the signal through the antenna 210, various components such as an encoder (not shown) and an ADC (not shown) required for signal generation may be included.
  • the backscatter communication signal processor 240 may transmit a signal (packet) using the reflection of the RF signal received from the primary user device through the antenna 210. That is, the backscatter communication signal processor 240 transmits '1' by reflecting the RF signal received from the primary user device, and transmits '0' if the RF signal is not reflected, or vice versa. .
  • the backscattered communication signal processor 240 may transmit a packet using reflection of an RF signal, rather than generating a signal.
  • the energy collector 250 is a device that generates power energy by receiving an RF signal from the primary user device. That is, the energy collector 250 receives the RF signal from the primary user device through the antenna 210 and converts it into a constant direct current to charge a battery (not shown).
  • the energy collector 250 includes an impedance matching circuit (not shown) for removing power loss of the RF signal received from the antenna 210 and a current converter (not shown) for converting an output RF signal of the impedance matching circuit into a direct current. And the like.
  • FIG. 8 is a channel state transition probability according to an embodiment of the present invention. Is a diagram illustrating packet transmission performance of a secondary user device that varies with time.
  • the packet transmission performance is degraded because the channel is frequently occupied by the primary user equipment, thereby decreasing the data transmission opportunity of the secondary user equipment.
  • the surrounding backscatter communication function it can be seen that even if is increased, the data transmission through the backscatter is possible, so that the packet transmission performance of the secondary user device continues to increase.
  • the secondary user device performs the backscattering with the dynamic probability in consideration of the energy level, it can be seen that high packet transmission performance can be obtained because the backscattering is preferentially performed when the energy is sufficient.

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Abstract

The present invention relates to a method for improving packet transmission performance of a second user in a cognitive wireless network, and a device therefor. A method for improving packet transmission performance of a second user in a cognitive wireless network according to the present invention, which is a method for improving packet transmission performance of a second user device in a cognitive wireless network, comprises the steps of: the second user device determining a state of channel occupancy by a first user device through spectrum sensing; the second user device selecting an operation mode from a backscatter mode and an energy harvesting mode on the basis of an energy level when the second user device accesses a channel occupied by the first user device; and the second user device operating according to the selected operation mode.

Description

인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법 및 그 장치Method and apparatus for improving packet transmission performance of secondary user in cognitive wireless network
본 발명은 인지 무선(Cognitive Radio; CR) 네트워크에서 주변 후방산란 통신(Ambient Backscatter Communication; AmBC) 기능을 갖는 2차 사용자 (Secondary User; SU)의 패킷 전송 성능을 향상시키는 방법 및 그 장치에 관한 것이다. The present invention relates to a method and apparatus for improving packet transmission performance of a secondary user (SU) having an ambient backscatter communication (AMBC) function in a cognitive radio (CR) network. .
나아가, 본 발명은 2018년 07월 23일 출원된 한국특허출원 제10-2018-0085558호의 이익을 주장하며, 그 내용 전부는 본 명세서에 포함된다.Furthermore, the present invention claims the benefit of Korean Patent Application No. 10-2018-0085558, filed July 23, 2018, the entire contents of which are incorporated herein.
점차 증가하는 무선 통신에 대한 사용자의 요구를 만족시키기 위해서는 충분한 주파수 대역의 확보가 필요하다. 그러나 통신에 활용 가능한 무선 주파수 대역은 한정적일 뿐만 아니라 대부분이 기존의 무선 통신 서비스(이하 주사용자, Primary User, PU)에 이미 할당되어 있기 때문에 새로운 통신 서비스를 위한 주파수 대역의 확보가 매우 힘든 실정이다. Sufficient frequency bands are required to meet the user's demand for an increasing number of wireless communications. However, it is very difficult to secure a frequency band for a new communication service because only a limited number of radio frequency bands are available for communication and most of them are already allocated to existing wireless communication services (hereinafter, primary user, PU). .
주파수 부족에 따른 문제를 해결하기 위해 패킷 스케줄링, 전송 능력 조절, 다중 홉 전송 등과 같이 한정된 주파수 자원을 보다 효율적으로 사용하는 자원 관리 연구가 활발히 이루어지고 있다. 그러나 이러한 연구는 물리적인 주파수 부족 문제를 해결할 수 없다는 한계를 지닌다. 주사용자에게 할당된 주파수 대역 중 많은 부분의 사용률이 매우 낮으며 이러한 경향은 특히 도시 외곽이나 인구 밀도가 낮은 지역에서 더욱 두드러진다. 인지 무선 기술(cognitive radio)은 지속적으로 변화하는 주파수 대역들의 사용 현황을 인지하고 빈 주파수 대역을 활용함으로써 전파 자원의 사용률을 극대화하기 위해 제안되었다.In order to solve the problems caused by the lack of frequency, resource management researches that use limited frequency resources more efficiently, such as packet scheduling, transmission capability adjustment, multi-hop transmission, etc., have been actively conducted. However, this research has a limitation that cannot solve the physical frequency shortage problem. Many of the frequency bands allocated to primary users are very low, and this tendency is especially pronounced outside urban areas or in low population densities. Cognitive radio technology (cognitive radio) has been proposed to maximize the utilization of radio resources by recognizing the use of the constantly changing frequency bands and utilizing the empty frequency band.
인지 무선 기술은 주사용자에게 할당된 채널이라도 특정 시간, 특정 지역에서 사용되고 있지 않다면 허가받지 않은 부사용자(Secondary User, SU)의 통신에 활용하여 고정적으로 할당받은 채널이 없어도 데이터를 송수신할 수 있는 기술이다.Cognitive radio technology is a technology that can transmit and receive data even if there is no fixedly allocated channel, even if the channel assigned to the main user is not used in a specific time and region, for the communication of unauthorized secondary users (SU). to be.
이러한 무선 인지 기술은 크게 오버레이(overlay) 기법과 언더레이(underlay) 기법이 있는데, 언더레이 기법은 주사용자가 동작 중인 주파수 대역이라 해도 인지 통신 네트워크가 동시에 데이터 송신을 할 수 있게 하되, 매우 낮은 전송 전력을 사용함으로써 주사용자가 느끼는 간섭의 정도가 매우 낮아 통신이 방해받지 않도록 하는 방식이다. 오버레이 기법은 주사용자가 통신을 진행 중인 채널에서는 부사용자가 데이터를 송수신할 수 없으며 주사용자가 없는 채널만을 활용하도록 하는 기법이다.The wireless cognitive technology includes an overlay technique and an underlay technique. The underlay technique enables a cognitive communication network to simultaneously transmit data even at a frequency band in which the main user operates, but at a very low transmission rate. The use of power allows the main user to have a very low level of interference so that communication is not interrupted. The overlay technique is a technique in which the sub-user cannot transmit / receive data in the channel where the main user is communicating and utilizes only the channel without the main user.
오버레이 기반의 인지 무선 네트워크는 주사용자가 존재하지 않는 것을 확인한 후에만 주파수 대역을 사용할 수 있는데 반해, 주사용자는 자신의 동작을 인지 무선 네트워크에게 알릴 의무가 없으므로 인지 무선 네트워크의 부사용자는 감지주기의 타임슬롯(time slot)마다 지속적으로 채널 상태를 관찰하여 주사용자가 전송을 시작하였는지 여부를 확인해야만 한다. Overlay-based cognitive radio networks can use the frequency band only after confirming that the primary user does not exist, whereas the primary user is not obliged to inform the cognitive radio network of its behavior, so that the secondary user of the cognitive radio network must The channel status must be continuously monitored at each time slot to determine whether the primary user has initiated transmission.
이처럼 오버레이 기반의 인지 무선 네트워크에서 SU는 일시적으로 비어 있는 채널에 접근하여 데이터를 전송하지만, 주사용자가 사용하고 있는 채널에 접근하면 데이터 전송을 포기하거나 지속적으로 비어 있는 채널에 접근하기 위해 다른 채널로 이동한다. 인지 무선 네트워크에서 에너지 수집(Energy Harvesting; EH) 기능을 갖는 부 사용자는 비어 있는 채널에 접근하여 데이터를 전송하고 주 사용자가 점유한 채널에 접근하면 에너지를 수집하거나 주 사용자가 일시적으로 사용하지 않는 채널에 접근하여 데이터를 전송한다. In this overlay-based cognitive wireless network, SU temporarily accesses an empty channel and transmits data, but when accessing a channel being used by a main user, SU gives up data transmission or goes to another channel to continuously access an empty channel. Move. In a cognitive wireless network, secondary users with Energy Harvesting (EH) access a channel that is empty and transmit data, and when the primary user accesses a channel that the primary user occupies, collects energy or temporarily disables the primary user. Access to transfer data.
그러나, 종래의 인지 무선 네트워크에서 부 사용자는 비어 있는 채널이 없으면 데이터를 전송할 수 없고, 이로 인해 부 사용자의 데이터 전송 성능을 향상시키는데 한계가 있다. However, in the conventional cognitive radio network, the secondary user cannot transmit data without an empty channel, which limits the improvement of data transmission performance of the secondary user.
따라서, 인지 무선 네트워크에서 부 사용자의 데이터 전송 성능을 향상시킬 수 있는 기술 개발이 요구되고 있다. Therefore, there is a need for a technology development capable of improving data transmission performance of secondary users in cognitive wireless networks.
이와 관련하여, 발명의 명칭이 "주파수 공유 인지 무선 네트워크에서 이차 사용자의 중계기가 에너지 하베스팅하여 이차 사용자의 정보를 중계하는 시스템"인 한국공개특허 제10-2016-0036279호가 존재한다.In this regard, there is a Korean Patent Application Publication No. 10-2016-0036279 entitled "System that relays information of a secondary user by harvesting energy of a repeater of a secondary user in a frequency shared cognitive wireless network".
본 발명은 인지 무선(Cognitive Radio; CR) 네트워크에서 주변 후방산란 통신(Ambient Backscatter Communication; AmBC) 기능을 갖는 2차 사용자 (Secondary User; SU)의 패킷 전송 성능을 향상시킬수 있는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법 및 그 장치를 제공하는데 그 목적이 있다.The present invention is a secondary network in a cognitive radio network capable of improving packet transmission performance of a secondary user (SU) having an ambient backscatter communication (AMBC) function in a cognitive radio (CR) network. An object of the present invention is to provide a method and apparatus for improving packet transmission performance of a user.
본 발명이 해결하고자 하는 과제는 이상에서 언급한 과제(들)로 제한되지 않으며, 언급되지 않은 또 다른 과제(들)은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.The problem to be solved by the present invention is not limited to the above-mentioned task (s), another task (s) not mentioned will be clearly understood by those skilled in the art from the following description.
상기의 목적을 달성하기 위해 본 발명의 일 실시예에 따른 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법은, 인지 무선 네트워크에서 2차 사용자 장치의 패킷 전송 성능 개선을 위한 방법에 있어서, 상기 2차 사용자 장치는, 스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단하는 단계, 상기 2차 사용자 장치는, 1차 사용자 장치에 의해 점유된 채널에 접근한 경우, 에너지 레벨에 기초하여 후방산란 모드 또는 에너지 수집 모드의 동작모드를 결정하는 단계, 상기 2차 사용자 장치는 상기 결정된 동작모드에 따라 동작하는 단계를 포함한다. In order to achieve the above object, a method for improving packet transmission performance of a secondary user in a cognitive wireless network according to an embodiment of the present invention is a method for improving packet transmission performance of a secondary user device in a cognitive wireless network. Determining, by the secondary user device, the channel occupancy state of the primary user device by spectrum sensing; when the secondary user device approaches a channel occupied by the primary user device, backscattering is performed based on the energy level. Determining an operating mode of the mode or the energy collection mode, wherein the secondary user device operates according to the determined operating mode.
바람직하게는, 상기 채널 점유 상태를 판단하는 단계는, 슬롯의 시작점에서 일정 시간동안 샘플링 주파수로 에너지 검출을 수행하여 채널의 점유 상태를 판단할 수 있다. Preferably, in the determining of the channel occupancy state, the energy occupancy of the channel may be determined by performing energy detection at a sampling frequency for a predetermined time at the start of the slot.
바람직하게는, 상기 동작모드를 결정하는 단계는, 상기 에너지 레벨에 따른 후방산란 확률을 산출하는 단계, '0'부터 '1'사이의 크기를 갖는 랜덤값을 선택하고, 상기 선택된 랜덤값과 후방산란 확률 값을 비교하는 단계, 상기 랜덤 값이 후방산란 확률 값 이하인 경우 후방산란 모드로 결정하고, 후방산란 확률 값 이하가 아닌 경우 에너지 수집 모드로 결정하는 단계를 포함할 수 있다. Preferably, the determining of the operation mode may include calculating a backscattering probability according to the energy level, selecting a random value having a size between '0' and '1', and selecting the random value and the rear side. Comparing the scattering probability value, if the random value is less than the backscattering probability value may be determined as the backscattering mode, and if it is not less than the backscattering probability value may comprise the step of determining the energy collection mode.
바람직하게는, 상기 에너지 레벨에 따른 후방산란 확률(
Figure PCTKR2018016876-appb-I000001
)은 아래 수학식으로 산출될 수 있다. Preferably, the backscattering probability according to the energy level (
Figure PCTKR2018016876-appb-I000001
) May be calculated by the following equation.
[수학식][Equation]
Figure PCTKR2018016876-appb-I000002
Figure PCTKR2018016876-appb-I000002
여기서, l은 2차 사용자 장치의 에너지 레벨, L은 에너지 최대 레벨,
Figure PCTKR2018016876-appb-I000003
은 슬롯 m에서의 채널 센싱 결과를 의미함.Where l is the energy level of the secondary user device, L is the energy maximum level,
Figure PCTKR2018016876-appb-I000003
Denotes the result of channel sensing in slot m.
바람직하게는, 상기 동작하는 단계는, 상기 결정된 동작모드가 후방산란 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 반사하여 패킷을 전송하고, 상기 결정된 동작모드가 에너지 수집 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 이용하여 에너지 하베스팅을 수행할 수 있다. Preferably, the operation may include transmitting a packet by reflecting an RF signal from the primary user device when the determined operation mode is a backscattering mode, and when the determined operation mode is an energy collection mode, Energy harvesting may be performed using the RF signal from the primary user device.
바람직하게는, 상기 2차 사용자 장치는 1차 사용자 장치에 의해 점유되지 않은 채널에 접근한 경우, 무선 전송 방식으로 패킷을 전송할 수 있다. Preferably, when the secondary user device accesses a channel not occupied by the primary user device, the secondary user device may transmit a packet by a wireless transmission method.
바람직하게는, 상기 2차 사용자 장치는 후방산란 모드 또는 무선전송 방식으로 패킷을 전송하고, 패킷 전송 성능(R)은 아래 수학식으로 정의될 수 있다. Preferably, the secondary user device transmits a packet in a backscattering mode or a wireless transmission method, and the packet transmission performance R may be defined by the following equation.
[수학식] [Equation]
Figure PCTKR2018016876-appb-I000004
Figure PCTKR2018016876-appb-I000004
여기서,
Figure PCTKR2018016876-appb-I000005
은 에너지 레벨
Figure PCTKR2018016876-appb-I000006
이 발생할 확률,
Figure PCTKR2018016876-appb-I000007
은 슬롯 m에서의 채널 센싱 결과,
Figure PCTKR2018016876-appb-I000008
은 슬롯 m에서의 채널 점유 상태,
Figure PCTKR2018016876-appb-I000009
은 무선전송 방식으로 1차 사용자 장치와의 충돌없이 패킷을 전송할 확률,
Figure PCTKR2018016876-appb-I000010
은 후방산란 모드로 패킷을 전송할 확률,
Figure PCTKR2018016876-appb-I000011
은 후방산란 확률을 의미함.here,
Figure PCTKR2018016876-appb-I000005
Silver energy level
Figure PCTKR2018016876-appb-I000006
Probability of this occurring,
Figure PCTKR2018016876-appb-I000007
Is the channel sensing result in slot m,
Figure PCTKR2018016876-appb-I000008
Is the channel occupancy state in slot m,
Figure PCTKR2018016876-appb-I000009
Is the probability of transmitting a packet without collision with a primary user device through a wireless transmission method,
Figure PCTKR2018016876-appb-I000010
Is the probability of sending a packet in backscattering mode,
Figure PCTKR2018016876-appb-I000011
Is the probability of backscattering.
바람직하게는, 상기 에너지 레벨 l이 발생할 확률(
Figure PCTKR2018016876-appb-I000012
)은 에너지 레벨 전이 확률을 고려한 아래 수학식에 의해 정의될 수 있다. Preferably, the probability that the energy level l will occur (
Figure PCTKR2018016876-appb-I000012
) Can be defined by the following equation considering the energy level transition probability.
[수학식] [Equation]
Figure PCTKR2018016876-appb-I000013
Figure PCTKR2018016876-appb-I000013
여기서,
Figure PCTKR2018016876-appb-I000014
,
Figure PCTKR2018016876-appb-I000015
, Pc는 에너지를 소모할 확률로
Figure PCTKR2018016876-appb-I000016
, Pd는 검출 확률을 의미함.here,
Figure PCTKR2018016876-appb-I000014
,
Figure PCTKR2018016876-appb-I000015
, Pc is the probability of consuming energy
Figure PCTKR2018016876-appb-I000016
, Pd means the detection probability.
상기의 목적을 달성하기 위해 본 발명의 다른 실시예에 따른 인지 무선 네트워크에서 패킷 전송 성능 개선을 위한 2차 사용자 장치에 있어서, 스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단하고, 1차 사용자 장치에 의해 점유된 채널에 접근한 경우, 에너지 레벨에 기초하여 후방산란 모드 또는 에너지 수집 모드의 동작모드를 결정하는 제어부, 상기 제어부에서 결정된 동작모드가 후방산란 모드인 경우, 1차 사용자 장치로부터 수신한 RF 신호의 반사를 이용하여 패킷을 전송하는 후방산란 통신 신호 처리부, 상기 제어부에서 결정된 동작 모드가 에너지 수집 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 이용하여 에너지 하베스팅을 수행하는 에너지 수집부를 포함한다. In order to achieve the above object, in a secondary user device for improving packet transmission performance in a cognitive wireless network according to another embodiment of the present invention, the channel occupancy state of the primary user device is determined by spectrum sensing, and the primary user A control unit for determining an operation mode of the backscattering mode or the energy collection mode based on the energy level when the channel occupied by the device is received from the primary user device when the operation mode determined by the control unit is the backscattering mode Backscatter communication signal processing unit for transmitting the packet by using the reflection of the RF signal, the energy to perform energy harvesting using the RF signal from the primary user device when the operation mode determined by the control unit is the energy collection mode It includes a collector.
바람직하게는, 상기 1차 사용자 장치에 의해 점유되지 않은 채널에 접근한 경우, 무선 전송 방식으로 패킷을 전송하는 무선통신 신호 처리부를 더 포함할 수 있다.Preferably, the method may further include a wireless communication signal processor for transmitting a packet by a wireless transmission method when a channel not occupied by the primary user device is accessed.
본 발명에 의하면, 주 사용자가 점유한 채널에 접근하였을 때 주변 후방산란 통신(Ambient Backscatter Communication; AmBC)으로 패킷을 전송함으로써, 2차 사용자의 패킷 전송 성능을 향상시킬 수 있다. According to the present invention, when a primary user accesses a channel occupied, the packet transmission performance of the secondary user can be improved by transmitting a packet to ambient backscatter communication (AMBC).
또한, 2차 사용자의 에너지 레벨을 고려하여 후방산란을 진행하기 때문에 기존에 비해 개선된 전송 성능을 얻을 수 있고, 사물인터넷을 구성하는 무선충전 단말의 주파수 사용 효율과 에너지 효율을 개선시키는 동시에 개선된 전송 성능을 얻을 수 있다. In addition, since backscattering is performed in consideration of the energy level of the secondary user, it is possible to obtain improved transmission performance, and to improve the frequency use efficiency and energy efficiency of the wireless charging terminal constituting the IoT. Transmission performance can be obtained.
또한, 2차 사용자가 보유하고 있는 에너지가 충분하면 에너지 수집보다 후방산란을 우선적으로 수행하기 때문에 정적 확률로 후방산란을 수행하는 경우보다 높은 패킷 전송 성능을 얻을 수 있다.In addition, if the secondary user has enough energy, since backscattering is prioritized over energy collection, higher packet transmission performance can be obtained than when backscattering is performed with a static probability.
본 발명의 효과들은 이상에서 언급한 효과들로 제한되지 않으며, 언급되지 않은 또 다른 효과들은 아래의 기재로부터 통상의 기술자에게 명확하게 이해될 수 있을 것이다.Effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.
도 1은 본 발명의 일 실시예에 따른 2차 사용자의 패킷 전송 성능 개선을 위한 인지 무선 네트워크를 설명하기 위한 도면이다.1 is a diagram illustrating a cognitive radio network for improving packet transmission performance of a secondary user according to an embodiment of the present invention.
도 2는 본 발명의 일 실시예에 따른 인지 무선 네트워크에서 2차 사용자 장치의 동작을 설명하기 위한 도면이다. 2 is a diagram illustrating an operation of a secondary user device in a cognitive wireless network according to an embodiment of the present invention.
도 3은 본 발명의 일 실시예에 따른 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법을 설명하기 위한 도면이다. 3 is a diagram illustrating a method for improving packet transmission performance of a secondary user in a cognitive wireless network according to an embodiment of the present invention.
도 4는 본 발명의 일 실시예에 따른 2차 사용자 장치의 에너지 레벨 종속적 전송을 설명하기 위한 예시도이다. 4 is an exemplary diagram for explaining energy level dependent transmission of a secondary user device according to an embodiment of the present invention.
도 5는 본 발명의 일 실시예에 따른 2차 사용자 장치의 에너지 모델을 설명하기 위한 도면이다.FIG. 5 is a diagram for describing an energy model of a secondary user device according to an exemplary embodiment.
도 6은 본 발명의 일 실시예에 따른 1차 사용자 장치의 채널 모델을 설명하기 위한 도면이다.FIG. 6 illustrates a channel model of a primary user device according to an embodiment of the present invention.
도 7은 본 발명의 일 실시예에 따른 2차 사용자 장치를 설명하기 위한 도면이다.7 is a view for explaining a secondary user device according to an embodiment of the present invention.
도 8은 본 발명의 일 실시예에 따른 채널 상태 전이확률
Figure PCTKR2018016876-appb-I000017
에 따라 변화하는 2차 사용자 장치의 패킷 전송 성능을 나타낸 도면이다.8 is a channel state transition probability according to an embodiment of the present invention.
Figure PCTKR2018016876-appb-I000017
Is a diagram illustrating packet transmission performance of a secondary user device that varies with time.
본 발명은 다양한 변경을 가할 수 있고 여러 가지 실시예를 가질 수 있는 바, 특정 실시예들을 도면을 참조하여 상세하게 설명하도록 한다. 그러나, 이는 본 발명을 특정한 실시 형태에 대해 한정하려는 것이 아니며, 본 발명의 사상 및 기술 범위에 포함되는 모든 변경, 균등물 내지 대체물을 포함하는 것으로 이해되어야 한다. 각 도면을 설명하면서 유사한 참조부호를 유사한 구성요소에 대해 사용하였다.As the present invention allows for various changes and numerous embodiments, particular embodiments will be described in detail with reference to the accompanying drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.
제1, 제2, A, B 등의 용어는 다양한 구성요소들을 설명하는데 사용될 수 있지만, 상기 구성요소들은 상기 용어들에 의해 한정되어서는 안된다. 상기 용어들은 하나의 구성요소를 다른 구성요소로부터 구별하는 목적으로만 사용된다. 예를 들어, 본 발명의 권리범위를 벗어나지 않으면서 제1 구성요소는 제2 구성요소로 명명될 수 있고, 유사하게 제2 구성요소도 제1 구성요소로 명명될 수 있다. 및/또는 이라는 용어는 복수의 관련된 기재 항목들의 조합 또는 복수의 관련된 기재 항목들 중의 어느 항목을 포함한다.Terms such as first, second, A, and B 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 of a plurality of related description items or a combination of a plurality of related description items.
어떤 구성요소가 다른 구성요소에 "연결되어" 있다거나 "접속되어" 있다고 언급될 때에는 그 다른 구성요소에 직접적으로 연결되어 있거나 또는 접속되어 있을 수도 있지만, 중간에 다른 구성요소가 존재할 수도 있다고 이해되어야 할 것이다. 반면에, 어떤 구성요소가 다른 구성요소에 "직접 연결되어" 있다거나 "직접 접속되어" 있다고 언급된 때에는, 중간에 다른 구성요소가 존재하지 않는 것으로 이해되어야 할 것이다. When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to the other component, but it should be understood that there may be other components in between. something to do. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.
본 출원에서 사용한 용어는 단지 특정한 실시예를 설명하기 위해 사용된 것으로, 본 발명을 한정하려는 의도가 아니다. 단수의 표현은 문맥상 명백하게 다르게 뜻하지 않는 한, 복수의 표현을 포함한다. 본 출원에서, "포함하다" 또는 "가지다" 등의 용어는 명세서상에 기재된 특징, 숫자, 단계, 동작, 구성요소, 부품 또는 이들을 조합한 것이 존재함을 지정하려는 것이지, 하나 또는 그 이상의 다른 특징들이나 숫자, 단계, 동작, 구성요소, 부품 또는 이들을 조합한 것들의 존재 또는 부가 가능성을 미리 배제하지 않는 것으로 이해되어야 한다.The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.
다르게 정의되지 않는 한, 기술적이거나 과학적인 용어를 포함해서 여기서 사용되는 모든 용어들은 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자에 의해 일반적으로 이해되는 것과 동일한 의미를 가지고 있다. 일반적으로 사용되는 사전에 정의되어 있는 것과 같은 용어들은 관련 기술의 문맥 상 가지는 의미와 일치하는 의미를 가지는 것으로 해석되어야 하며, 본 출원에서 명백하게 정의하지 않는 한, 이상적이거나 과도하게 형식적인 의미로 해석되지 않는다.Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.
명세서 및 청구범위 전체에서, 어떤 부분이 어떤 구성 요소를 포함한다고 할때, 이는 특별히 반대되는 기재가 없는 한 다른 구성 요소를 제외하는 것이 아니라 다른 구성 요소를 더 포함할 수 있다는 것을 의미한다. Throughout the specification and claims, when a part includes a certain component, it means that it may further include other components, except to exclude other components unless specifically stated otherwise.
본 발명은 면허대역을 사용하는 1차 사용자 장치가 일시적으로 채널을 점유하지 않을 때 면허대역을 할당받지 못한 2차 사용자 장치가 기회적으로 채널에 접근하여 데이터를 전송하는 인지 무선 기술과 1차 사용자 장치가 사용하는 채널에 접근하여 에너지를 수집하는 무선충전 기술을 기반으로 한다. The present invention relates to a cognitive radio technology and a primary user, in which a secondary user device that has not been allocated a license band has an opportunity to access a channel and transmit data when a primary user device that uses a licensed band temporarily does not occupy a channel. It is based on wireless charging technology that collects energy by accessing the channel used by the device.
또한, 본 명세서 기재된 1차 사용자 장치는 주사용자(Primary User. PU)와 동일한 용어이고, 2차 사용자 장치는 부사용자(Secondary User; SU)와 동일한 용어이다. In addition, the primary user device described herein is the same term as the Primary User (PU), and the secondary user device is the same term as the Secondary User (SU).
이하, 본 발명에 따른 바람직한 실시예를 첨부된 도면을 참조하여 상세하게 설명한다.Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 본 발명의 일 실시예에 따른 2차 사용자의 패킷 전송 성능 개선을 위한 인지 무선 네트워크를 설명하기 위한 도면, 도 2는 본 발명의 일 실시예에 따른 인지 무선 네트워크에서 2차 사용자 장치의 동작을 설명하기 위한 도면이다. 1 is a diagram illustrating a cognitive wireless network for improving packet transmission performance of a secondary user according to an embodiment of the present invention, and FIG. 2 is a diagram of a secondary user device in a cognitive wireless network according to an embodiment of the present invention. It is a figure for demonstrating operation | movement.
도 1을 참조하면, 본 발명의 일 실시예에 따른 2차 사용자의 패킷 전송 성능 개선을 위한 인지 무선 네트워크는 2차 사용자 장치들(200a, 200b, .., 200n, 이하 200이라 칭함)이 스스로 채널을 감지하여 1차 사용자 장치(100)에 할당된 채널들에 대해 1차 사용자의 점유(사용) 여부를 판단한다. 무선 인지 네트워크는 다수의 채널(ch1, ch2,..., chn)로 구성되어 있는데 1차 사용자 장치(100)는 다수의 채널을 2차 사용자 장치(200)의 방해를 받지 않고 사용하며, 2차 사용자 장치(200)는 1차 사용자 장치(100)를 방해하지 않으며 채널을 선택적으로 사용한다. 각 채널은 1차 사용자 장치(100)가 사용하는 시간(occupied)과 사용하지 않는 시간(idle)로 구분된다. 1차 사용자 장치(100)가 채널을 사용하는 시간 동안 채널은 점유 채널로 동작하며, 1차 사용자 장치(100)가 채널을 사용하지 않는 시간 동안 채널은 비점유 채널(비어있는 채널)로 동작한다.Referring to FIG. 1, in a cognitive wireless network for improving packet transmission performance of a secondary user according to an embodiment of the present invention, secondary user devices 200a, 200b,. The channel is detected to determine whether the primary user occupies (uses) the channels allocated to the primary user device 100. The wireless cognitive network is composed of a plurality of channels (ch1, ch2, ..., chn), the primary user device 100 uses a plurality of channels without interference from the secondary user device 200, 2 The primary user device 200 selectively uses a channel without disturbing the primary user device 100. Each channel is divided into an occupied time and an idle time that the primary user device 100 uses. The channel operates as an occupied channel during the time when the primary user device 100 uses the channel, and the channel operates as an unoccupied channel (empty channel) during the time when the primary user device 100 does not use the channel. .
2차 사용자 장치(200)는 1차 사용자 장치(100)가 점유한 채널에 접근하였을 때 에너지 레벨에 따라 후방산란 모드 또는 에너지 수집 모드로 동작한다. 여기서, 후방산란 모드는 도 2의 (a)와 같이 2차 사용자 장치(EH-ST)가 1차 사용자 장치(H-AP)로부터 수신한 신호를 반사하여 패킷(데이터)를 전송하는 것을 말한다. 에너지 수집(Energy Harvesting; EH) 모드는 도 2의 (b)와 같이 2차 사용자 장치(EH-ST, SR)가 1차 사용자 장치(H-AP)로부터 수신한 RF 신호를 에너지원으로 사용하는 것을 말한다. The secondary user device 200 operates in the backscattering mode or the energy collection mode according to the energy level when the primary user device 100 approaches the channel occupied. Here, the backscattering mode means that the secondary user device EH-ST transmits a packet (data) by reflecting a signal received from the primary user device H-AP as shown in FIG. Energy Harvesting (EH) mode uses the RF signal received from the primary user device (H-AP) by the secondary user device (EH-ST, SR) as an energy source, as shown in FIG. Say that.
또한, 2차 사용자 장치는 1차 사용자 장치에 의해 점유되지 않은 채널에 접근한 경우, 도 2의 (c)와 같이 기존의 무선 전송 방식으로 패킷을 전송한다. 즉, 2차 사용자 장치((EH-ST)는 신호를 생성하고, 그 생성된 신호를 무선전송 방식으로 다른 2차 사용자 장치(SR)로 전송한다. In addition, when the secondary user device accesses a channel that is not occupied by the primary user device, the secondary user device transmits the packet by the conventional wireless transmission method as shown in FIG. That is, the secondary user device (EH-ST) generates a signal and transmits the generated signal to another secondary user device SR through a wireless transmission method.
살핀바와 같이, CR 네트워크에서 2차 사용자 장치(200)는 점유된 채널에 접근하면 주변 신호를 반사하여 데이터를 전송하거나 에너지를 수집하게 되며, 비어 있는 채널에 접근하면 기존의 무선 전송 방식으로 데이터를 전송하게 된다.Like a salpin bar, in a CR network, a secondary user device 200 transmits data or collects energy by reflecting a peripheral signal when approaching an occupied channel, and accesses data using an existing wireless transmission method when an empty channel is accessed. Will be sent.
도 3은 본 발명의 일 실시예에 따른 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법을 설명하기 위한 도면, 도 4는 본 발명의 일 실시예에 따른 2차 사용자 장치의 에너지 레벨 종속적 전송을 설명하기 위한 예시도, 도 5는 본 발명의 일 실시예에 따른 2차 사용자 장치의 에너지 모델을 설명하기 위한 도면, 도 6은 본 발명의 일 실시예에 따른 1차 사용자 장치의 채널 모델을 설명하기 위한 도면이다.3 is a diagram illustrating a method for improving packet transmission performance of a secondary user in a cognitive wireless network according to an embodiment of the present invention, and FIG. 4 is an energy level dependent transmission of a secondary user device according to an embodiment of the present invention. 5 is a view for explaining an energy model of a secondary user device according to an embodiment of the present invention, Figure 6 is a channel model of the primary user device according to an embodiment of the present invention It is a figure for demonstrating.
도 3을 참조하면, 2차 사용자 장치는 스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단한다(S310). Referring to FIG. 3, the secondary user device determines the channel occupancy state of the primary user device by spectrum sensing (S310).
즉, Overlay CRN에서 2차 사용자 장치는 채널의 점유 상태에 대한 정보가 주어지지 않기 때문에, 슬롯(구간 T)의 시작점에서
Figure PCTKR2018016876-appb-I000018
(센싱 구간,
Figure PCTKR2018016876-appb-I000019
) 동안 샘플링 주파수 f로 에너지 검출을 수행하여 센싱 결과
Figure PCTKR2018016876-appb-I000020
에 따라 채널의 점유 상태를 판단한다. 이때, 검출된 에너지가 선택한 검출 임계값보다 크면 센싱 결과는
Figure PCTKR2018016876-appb-I000021
이고, 그렇지 아니하면 센싱 결과는
Figure PCTKR2018016876-appb-I000022
으로 판단한다. 센싱 결과가
Figure PCTKR2018016876-appb-I000023
이면 채널이 점유되었다고 판단하고,
Figure PCTKR2018016876-appb-I000024
이면 채널이 비어 있다고 판단할 수 있다. That is, in the overlay CRN, since the secondary user equipment is not given information about the occupancy state of the channel, at the beginning of the slot (section T),
Figure PCTKR2018016876-appb-I000018
(Sensing section,
Figure PCTKR2018016876-appb-I000019
Results in sensing the energy with sampling frequency f
Figure PCTKR2018016876-appb-I000020
Determine the occupancy state of the channel according to. At this time, if the detected energy is greater than the selected detection threshold value, the sensing result is
Figure PCTKR2018016876-appb-I000021
Otherwise the sensing result is
Figure PCTKR2018016876-appb-I000022
Judging by. Sensing results
Figure PCTKR2018016876-appb-I000023
, The channel is considered occupied,
Figure PCTKR2018016876-appb-I000024
In this case, it can be determined that the channel is empty.
한편, 채널의 점유 상태 판단 시, 센싱 결과는 채널이 점유된 것으로 판단되었으나 실제로는 1차 사용자 장치가 채널을 점유하지 않은 경우가 있을 수 있다. 또한 센싱 결과는 채널이 비어 있는 것으로 판단되었으나 실제로는 1차 사용자 장치가 채널을 점유하는 경우가 있을 수 있다. 따라서, 2차 사용자 장치는 스펙트럼 센싱에 의한 오경보 확률과 검출 확률을 산출할 필요가 있다. 여기서, 오경보 확률은 2차 사용자 장치의 센싱 결과 채널이 점유된 것으로 판단되었으나 1차 사용자 장치가 채널을 점유하지 않은 경우의 확률을 의미한다. 검출 확률은 2차 사용자 장치의 센싱 결과 채널이 점유된 것으로 판단되고, 1차 사용자 장치가 채널을 점유한 경우의 확률을 의미한다.On the other hand, when determining the occupancy state of the channel, the sensing result is determined that the channel is occupied, but may actually be the first user device does not occupy the channel. In addition, in the sensing result, it is determined that the channel is empty, but in practice, the primary user device may occupy the channel. Therefore, the secondary user device needs to calculate the false alarm probability and the detection probability by spectrum sensing. Here, the false alarm probability refers to a probability when the channel is determined to be occupied by the second user device but the primary user device does not occupy the channel. The detection probability is determined when the channel is occupied by the sensing result of the secondary user device, and means a probability when the primary user device occupies the channel.
오경보 확률 Pf은 아래 기재된 수학식 1과 같이 정의되고, 검출 확률 Pd는 아래 기재된 수학식 2와 같이 정의된다. 이때, 1차 사용자 장치의 신호와 잡음을 모두 평균인 '0'이고, 분산이 각각
Figure PCTKR2018016876-appb-I000025
,
Figure PCTKR2018016876-appb-I000026
인 순환 대칭 복소 가우시안 신호로 가정하였다. 따라서 샘플의 개수
Figure PCTKR2018016876-appb-I000027
가 충분히 큰 경우에 오경보 확률 Pf와 검출 확률 Pd는 검출 임계값
Figure PCTKR2018016876-appb-I000028
에 의해 수학식 1과 수학식 2와 같이 표현할 수 있다. False alarm probability P f is defined as Equation 1 described below, and detection probability P d is defined as Equation 2 described below. In this case, the signal and noise of the primary user equipment are both '0' which is the average, and the variance is
Figure PCTKR2018016876-appb-I000025
,
Figure PCTKR2018016876-appb-I000026
It is assumed to be a cyclic symmetric complex Gaussian signal. Thus the number of samples
Figure PCTKR2018016876-appb-I000027
If is large enough, false alarm probability P f and detection probability P d are detection thresholds.
Figure PCTKR2018016876-appb-I000028
It can be expressed by Equations 1 and 2 as follows.
[수학식 1][Equation 1]
Figure PCTKR2018016876-appb-I000029
Figure PCTKR2018016876-appb-I000029
[수학식 2][Equation 2]
Figure PCTKR2018016876-appb-I000030
Figure PCTKR2018016876-appb-I000030
여기서, C는 1차 사용자 장치의 채널 상태,
Figure PCTKR2018016876-appb-I000031
는 2차 사용자 장치에서 측정한 1차 사용자 장치의 신호대잡음비(Signal-to-Noise Ratio; SNR), Q는 일반화된 마쿰 Q 함수(generalized Marcum Q-function)를 의미할 수 있다. Where C is the channel state of the primary user device,
Figure PCTKR2018016876-appb-I000031
Denotes a signal-to-noise ratio (SNR) of the primary user device measured by the secondary user device, and Q may mean a generalized Marcum Q-function.
단계 S310의 수행 후, 2차 사용자 장치가 1차 사용자 장치에 의해 점유된 채널에 접근하면(S320), 2차 사용자 장치는 에너지 레벨에 기초하여 후방산란 모드 또는 에너지 수집 모드의 동작모드를 결정한다(S330). 즉, 2차 사용자 장치는 1차 사용자 장치가 사용하고 있는 채널에 접근한 경우에 1차 사용자 장치의 신호로부터 에너지를 수집할 것인지 1차 사용자 장치로부터의 신호를 반사하여 데이터를 전송할 것인지에 대한 결정이 필요하다. After performing step S310, when the secondary user device approaches a channel occupied by the primary user device (S320), the secondary user device determines an operation mode of the backscattering mode or the energy collection mode based on the energy level. (S330). That is, the secondary user device determines whether to collect energy from the signal of the primary user device or transmit data by reflecting the signal from the primary user device when the primary user device approaches the channel being used. need.
이에, 2차 사용자 장치는 자신의 에너지 레벨(예컨대, 배터리 잔여량)을 확인하고, 그 에너지 레벨에 따른 후방산란 확률을 산출한다. 에너지 레벨에 따른 후방산란 확률(
Figure PCTKR2018016876-appb-I000032
)은 아래 수학식 3을 이용하여 산출할 수 있다. Accordingly, the secondary user device checks its energy level (eg, battery remaining amount) and calculates backscattering probability according to the energy level. Backscatter probability according to energy level (
Figure PCTKR2018016876-appb-I000032
) Can be calculated using Equation 3 below.
[수학식 3][Equation 3]
Figure PCTKR2018016876-appb-I000033
Figure PCTKR2018016876-appb-I000033
여기서, l은 2차 사용자 장치의 에너지 레벨, L은 에너지 최대 레벨,
Figure PCTKR2018016876-appb-I000034
은 슬롯 m에서의 채널 센싱 결과를 의미할 수 있다. Where l is the energy level of the secondary user device, L is the energy maximum level,
Figure PCTKR2018016876-appb-I000034
May mean a result of channel sensing in slot m.
상술한 바와 같이 2차 사용자 장치는 접근한 채널이 점유되었다고 판단한 경우(
Figure PCTKR2018016876-appb-I000035
)에 에너지 레벨 l에 종속적으로 후방산란 확률을 결정한다. 에너지 레벨에 종속적인 후방산란 확률은 도 4와 같이 도시될 수 있다. 도 4는 2차 사용자 장치가 패킷 전송에 필요한 에너지보다 적은 양의 에너지를 보유하고 있는 상태를 에너지 고갈 상태(l=0 )로 정의하고, 후방산란은 0.25
Figure PCTKR2018016876-appb-I000036
의 전력을 필요로 하기 때문에 전체 에너지 상태(
Figure PCTKR2018016876-appb-I000037
)에서 후방산란 모드로 동작할 수 있다는 것을 나타낸다. As described above, when the secondary user device determines that the accessed channel is occupied (
Figure PCTKR2018016876-appb-I000035
Determine the backscattering probability dependent on the energy level. The backscattering probability dependent on the energy level can be shown as in FIG. 4 defines a state in which the secondary user device has less energy than that required for packet transmission as an energy depletion state (l = 0), and the backscatter is 0.25
Figure PCTKR2018016876-appb-I000036
Because it requires a power of,
Figure PCTKR2018016876-appb-I000037
) Can operate in backscattering mode.
후방산란 확률 값이 산출되면, 2차 사용자 장치는 0부터 1 사이의 크기를 갖는 랜덤값을 선택하고, 선택된 랜덤값과 후방산란 확률 값을 비교한다. 그 비교결과 랜덤 값이 후방산란 확률 값 이하인 경우 후방산란 모드로 결정하고, 후방산란 확률 값 이하가 아닌 경우 에너지 수집 모드로 결정한다. When the backscatter probability value is calculated, the secondary user device selects a random value having a size between 0 and 1, and compares the selected random value with the backscatter probability value. As a result of the comparison, if the random value is less than or equal to the backscattering probability value, the backscattering mode is determined.
다시 말하면, 2차 사용자 장치는 저장된 에너지가 적으면 에너지 수집을 우선으로 수행하고, 보유한 에너지가 많을수록 에너지 수집보다 후방산란 모드를 우선적으로 수행한다. 즉, 2차 사용자 장치는 에너지 레벨이 높을수록 후방산란을 우선적으로 수행하고(Higher
Figure PCTKR2018016876-appb-I000038
), 에너지 레벨이 낮으면 에너지 수집을 우선적으로 수행한다(Higher (
Figure PCTKR2018016876-appb-I000039
)).In other words, the secondary user device preferentially performs energy collection when there is less energy stored, and preferentially performs backscattering mode over energy collection when more energy is held. That is, the secondary user device preferentially performs backscattering as the energy level is higher (Higher
Figure PCTKR2018016876-appb-I000038
If the energy level is low, energy collection is preferentially performed (Higher (
Figure PCTKR2018016876-appb-I000039
)).
단계 S330에서 결정된 동작모드가 후방산란 모드이면, 2차 사용자 장치는 1차 사용자 장치로부터의 RF 신호를 반사하여 패킷을 전송하고(S340a), 결정된 동작모드가 에너지 수집 모드이면, 1차 사용자 장치로부터의 RF 신호를 이용하여 에너지 하베스팅을 수행한다(S340b). If the operation mode determined in step S330 is the backscattering mode, the secondary user device reflects the RF signal from the primary user device and transmits the packet (S340a). If the determined operation mode is the energy collection mode, from the primary user device Energy harvesting is performed using the RF signal (S340b).
후방산란 모드인 경우, 2차 사용자 장치는 1차 사용자 장치로부터의 RF 신호를 반사하여 '1'이 전송된 것으로 할 수 있고, RF 신호를 반사하지 않으면 '0'이 전송된 것으로 할 수 있다. 이처럼, 2차 사용자 장치는 1차 사용자 장치로부터의 RF 신호 반사를 통해 패킷을 전송할 수 있다. In the backscattering mode, the secondary user device may assume that '1' is transmitted by reflecting the RF signal from the primary user device, or '0' if it does not reflect the RF signal. As such, the secondary user device may transmit the packet via RF signal reflection from the primary user device.
에너지 수집 모드인 경우, 2차 사용자 장치는 1차 사용자 장치로부터의 RF 신호를 수집하여 에너지를 저장한다. 즉, 2차 사용자 장치는 RF 신호를 에너지 원으로 사용한다.In the energy collection mode, the secondary user device collects RF signals from the primary user device to store energy. That is, the secondary user device uses the RF signal as an energy source.
만약, 단계 S320의 판단결과, 2차 사용자 장치가 1차 사용자에 의해 점유되지 않은 비어있는 채널에 접근하면(S350), 2차 사용자 장치는 기존의 무선 전송 방식으로 패킷을 전송한다(S370). 이때, 기존의 무선 전송 방식으로 패킷을 전송한다는 것은 2차 사용자 장치가 신호를 생성하여 송신한다는 것을 의미한다. If it is determined in step S320 that the secondary user device approaches an empty channel not occupied by the primary user (S350), the secondary user device transmits the packet by the conventional wireless transmission method (S370). In this case, transmitting the packet by the conventional wireless transmission means that the secondary user device generates and transmits a signal.
상술한 바와 같이 2차 사용자 장치는 1차 사용자 장치가 점유한 채널에 접근하였을 경우에는 후방산란으로 패킷을 전송하거나 에너지를 수집할 수 있고, 1차 사용자 장치가 점유하지 않은 채널에 접근하였을 경우에는 기존의 무선전송 방식으로 패킷을 전송할 수 있다.As described above, the secondary user device may transmit packets or collect energy when the primary user device approaches a channel occupied, and may collect energy when the primary user device accesses a channel not occupied. A packet can be transmitted by the conventional wireless transmission method.
이처럼 2차 사용자 장치는 실제로 점유된 채널에 접근하여 에너지 레벨 l에 종속적인 확률로 후방산란을 수행하거나, 기존과 마찬가지로 데이터 전송에 필요한 에너지를 보유하고 있으면서(
Figure PCTKR2018016876-appb-I000040
) 실제로 비어있는 채널에 접근하여(
Figure PCTKR2018016876-appb-I000041
) 데이터를 전송할 수 있다. As such, the secondary user device accesses the channel actually occupied and performs backscattering with a probability dependent on the energy level l, or has the energy necessary for data transmission as before (
Figure PCTKR2018016876-appb-I000040
) Actually accessing an empty channel (
Figure PCTKR2018016876-appb-I000041
) You can transfer data.
따라서, 2차 사용자 장치의 패킷 전송 성능(R)은 아래 수학식 4와 같게 된다.Therefore, the packet transmission performance R of the secondary user device is expressed by Equation 4 below.
[수학식 4][Equation 4]
Figure PCTKR2018016876-appb-I000042
Figure PCTKR2018016876-appb-I000042
여기서,
Figure PCTKR2018016876-appb-I000043
은 에너지 레벨이
Figure PCTKR2018016876-appb-I000044
될 정상확률,
Figure PCTKR2018016876-appb-I000045
은 슬롯 m에서의 채널 센싱 결과,
Figure PCTKR2018016876-appb-I000046
은 슬롯 m에서의 채널 점유 상태를 의미할 수 있다. here,
Figure PCTKR2018016876-appb-I000043
The energy level
Figure PCTKR2018016876-appb-I000044
Be normal probability,
Figure PCTKR2018016876-appb-I000045
Is the channel sensing result in slot m,
Figure PCTKR2018016876-appb-I000046
May mean a channel occupancy state in the slot m.
수학식 4에서 좌측항목(Transmitting)은 비어있는 채널에 접근하여 데이터를 전송한 경우, 우측항목(Backsacttering)은 후방산란을 수행한 경우를 의미한다. 또한, 수학식 4에서 2차 사용자 장치의 에너지 레벨 l이 발생할 확률(
Figure PCTKR2018016876-appb-I000047
)은 에너지 전이 확률을 고려한 아래 수학식 5와 같이 정의할 수 있다.In Equation 4, the left item (Transmitting) refers to the case of performing backscattering when the data is accessed by accessing an empty channel. Further, in Equation 4, the probability that the energy level l of the secondary user device occurs (
Figure PCTKR2018016876-appb-I000047
) Can be defined as Equation 5 below considering the energy transfer probability.
[수학식 5][Equation 5]
Figure PCTKR2018016876-appb-I000048
Figure PCTKR2018016876-appb-I000048
여기서,
Figure PCTKR2018016876-appb-I000049
, Pc는 에너지를 소모할 확률, Pd는 검출 확률,
Figure PCTKR2018016876-appb-I000050
는 에너지 고갈 상태
Figure PCTKR2018016876-appb-I000051
이 발생할 확률로
Figure PCTKR2018016876-appb-I000052
로부터 계산될 수 있다. here,
Figure PCTKR2018016876-appb-I000049
, Pc is the probability of consuming energy, Pd is the probability of detection,
Figure PCTKR2018016876-appb-I000050
Energy depleted state
Figure PCTKR2018016876-appb-I000051
With a probability
Figure PCTKR2018016876-appb-I000052
Can be calculated from
수학식 5에서 에너지 고갈 상태가 발생할 확률
Figure PCTKR2018016876-appb-I000053
을 산출하기 위해서는 에너지 레벨 전이확률을 고려한 에너지 모델이 필요하고, 에너지 모델은 도 5와 같을 수 있다. 에너지 모델을 구축하기 위해서는 에너지를 소모할 확률, 에너지를 수집할 확률, 에너지 상태가 변하지 않을 확률이 필요하다.Probability of Depletion of Energy in Equation 5
Figure PCTKR2018016876-appb-I000053
In order to calculate the energy model considering the energy level transition probability is required, the energy model may be as shown in FIG. To build an energy model, you need the probability of consuming energy, the probability of collecting energy, and the probability that the energy state will not change.
먼저, 2차 사용자 장치의 센싱 결과가 '1'이면, 2차 사용자 장치는 데이터 전송을 시도하기 때문에 아래 수학식 6의 확률로 에너지를 소모하여 에너지 레벨이 하위 레벨로 전이하게 된다. 수학식 6은 에너지를 소모할 확률을 산출하는 식일 수 있다. First, when the sensing result of the secondary user device is '1', since the secondary user device attempts to transmit data, the energy level is transferred to the lower level by consuming energy with the probability of Equation 6 below. Equation 6 may be an equation for calculating the probability of consuming energy.
[수학식 6][Equation 6]
Figure PCTKR2018016876-appb-I000054
Figure PCTKR2018016876-appb-I000054
다음으로, 2차 사용자 장치의 센싱 결과가 '1'이고, 실제로 채널이 점유된 경우, 2차 사용자 장치는 후방산란을 수행하지 않고 에너지를 수집하여야만 2차 사용자 장치의 에너지 레벨이 상위 레벨로 전이할 수 있다. 따라서, 에너지를 수집할 확률은 아래 수학식 7과 같이 정의할 수 있다. Next, if the sensing result of the secondary user device is '1' and the channel is actually occupied, the secondary user device must collect energy without performing backscattering before the energy level of the secondary user device is transferred to a higher level. can do. Therefore, the probability of collecting energy may be defined as in Equation 7 below.
[수학식 7][Equation 7]
Figure PCTKR2018016876-appb-I000055
Figure PCTKR2018016876-appb-I000055
마지막으로 비어 있는 채널을 사용하고 있다고 판단할 오경보 확률과 후방산란을 수행하는 경우에는 에너지 레벨에 변화가 없게 된다. 따라서, 에너지 상태가 변하지 않을 확률은 아래 수학식 9와 같이 정의할 수 있다. Lastly, if false alarm probability and backscattering are judged to use an empty channel, there is no change in energy level. Therefore, the probability that the energy state does not change may be defined as in Equation 9 below.
[수학식 8][Equation 8]
Figure PCTKR2018016876-appb-I000056
Figure PCTKR2018016876-appb-I000056
에너지 모델의 에너지를 소모할 확률, 에너지를 수집할 확률, 에너지 상태가 변하지 않을 확률을 산출하기 위해 1차 사용자 장치의 채널 상태는 도 6과 같이 모델링될 수 있다. 도 6을 참조하면, 1차 사용자 장치의 채널 상태는 서로 상관된 2개의 상태 {idle (C=0), occupied (C=1)}로 모델링될 수 있다. In order to calculate a probability of consuming energy of the energy model, a probability of collecting energy, and a probability that the energy state does not change, the channel state of the primary user device may be modeled as shown in FIG. 6. Referring to FIG. 6, the channel state of the primary user device may be modeled as two states {idle (C = 0) and occupied (C = 1)} correlated with each other.
슬롯 m에서 채널이 비어 있을 확률을
Figure PCTKR2018016876-appb-I000057
, 채널이 1차 사용자 장치에 의해 점유될 확률을
Figure PCTKR2018016876-appb-I000058
로 정의하면 아래 수학식 9의 안정상태 방정식으로부터
Figure PCTKR2018016876-appb-I000059
와
Figure PCTKR2018016876-appb-I000060
를 구할 수 있다.The probability that the channel is empty in slot m
Figure PCTKR2018016876-appb-I000057
, The probability that the channel will be occupied by the primary user
Figure PCTKR2018016876-appb-I000058
If we define as from the steady state equation
Figure PCTKR2018016876-appb-I000059
Wow
Figure PCTKR2018016876-appb-I000060
Can be obtained.
[수학식 9][Equation 9]
Figure PCTKR2018016876-appb-I000061
Figure PCTKR2018016876-appb-I000061
여기서, Po는 채널상태 전이 확률을 의미한다.Here, Po means channel state transition probability.
따라서, 2차 사용자 장치가 에너지를 소모할 확률, 에너지를 수집할 확률, 에너지 상태가 변하지 않을 확률을 구하여 에너지 모델을 구축할 수 있으며, 에너지 모델로부터 에너지 고갈 상태가 발생할 안정상태 확률을 산출할 수 있다. Therefore, an energy model can be constructed by calculating the probability that the secondary user device consumes energy, the probability of collecting energy, and the probability that the energy state does not change, and the steady state probability of generating an energy depletion state can be calculated from the energy model. have.
상술한 과정을 통해 2차 사용자 장치는 패킷 전송 성능을 향상시킬 수 있다. 즉, 2차 사용자 장치는 보유하고 있는 에너지가 충분하면 에너지 수집보다 후방산란을 우선적으로 수행하기 때문에 정적 확률로 후방산란을 수행하는 경우보다 높은 패킷 전송 성능을 얻을 수 있다.Through the above-described process, the secondary user device can improve packet transmission performance. That is, since the secondary user device preferentially performs backscattering rather than energy collection if sufficient energy is retained, it is possible to obtain higher packet transmission performance than performing backscattering with a static probability.
도 7은 본 발명의 일 실시예에 따른 2차 사용자 장치를 설명하기 위한 도면이다.7 is a view for explaining a secondary user device according to an embodiment of the present invention.
도 7을 참조하면, 본 발명의 일 실시예에 따른 2차 사용자 장치(200)는 안테나(210), 제어부(220), 무선통신 신호 처리부(230), 후방산란통신 신호 처리부(240), 에너지 수집부(250)를 포함한다.Referring to FIG. 7, the secondary user device 200 according to an embodiment of the present invention may include an antenna 210, a controller 220, a wireless communication signal processor 230, a backscatter communication signal processor 240, and energy. And a collecting unit 250.
제어부(220)는 스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단하고, 점유되지 않은 채널에 접근한 경우 무선통신 신호 처리부(230)가 동작하도록 제어하고, 점유된 채널에 접근한 경우 에너지 레벨에 기초하여 후방산란통신 신호 처리부(240) 또는 에너지 수집부(250)가 동작하도록 제어한다.The controller 220 determines the channel occupancy state of the primary user device by spectrum sensing, controls the wireless communication signal processor 230 to operate when an unoccupied channel is accessed, and an energy level when the occupied channel is accessed. Based on the control of the backscatter communication signal processor 240 or the energy collector 250 to operate.
구체적으로, 제어부(220)는 슬롯의 시작점에서 일정 시간동안 샘플링 주파수로 에너지 검출을 수행하여 센싱 결과(
Figure PCTKR2018016876-appb-I000062
)에 따라 채널의 점유 상태를 판단한다. 이때,
Figure PCTKR2018016876-appb-I000063
이면 채널이 점유되었다고 판단하고,
Figure PCTKR2018016876-appb-I000064
이면 채널이 비어있다고 판단할 수 있다. Specifically, the control unit 220 performs the energy detection at a sampling frequency for a predetermined time at the start of the slot to detect the sensing result (
Figure PCTKR2018016876-appb-I000062
Determine the occupancy state of the channel according to). At this time,
Figure PCTKR2018016876-appb-I000063
, The channel is considered occupied,
Figure PCTKR2018016876-appb-I000064
If so, it can be determined that the channel is empty.
그런 후, 제어부(220)는 점유되지 않은 채널에 접근한 경우, 무선통신 신호 처리부(230)가 동작하도록 제어한다. 만약, 점유되지 않은 채널에 접근하면, 제어부(220)는 에너지 레벨에 따른 후방산란 확률을 산출하고, 그 후방산란 확률을 0부터 1 사이에서 랜덤하게 선택된 값과 비교하여, 랜덤값이 후방산란 확률 값 이하인 경우 후방산란통신 신호 처리부(240)가 동작하도록 제어하고, 후방산란 확률 값 이하가 아닌 경우 에너지 수집부(250)가 동작하도록 제어한다. Thereafter, the controller 220 controls the wireless communication signal processor 230 to operate when an unoccupied channel is approached. If the channel is not occupied, the controller 220 calculates the backscattering probability according to the energy level, and compares the backscattering probability with a value randomly selected from 0 to 1, so that the random value is the backscattering probability. When the value is less than the value, the backscatter communication signal processor 240 is controlled to operate. When the value is not less than the backscattered probability value, the energy collector 250 is controlled.
무선통신 신호 처리부(230)는 RF 신호를 생성하여 안테나(210)를 통해 전송한다. 이때, 무선통신 신호 처리부(230)는 사용하는 무선 통신 기법에 따라 부호화(encoding)하여 신호를 생성하고, 생성된 신호를 안테나(210)를 통해 송신한다. 이때, 무선 통신 기법은 블루투스, 와이파이 등 다양한 통신 방법일 수 있다. The wireless communication signal processor 230 generates an RF signal and transmits it through the antenna 210. At this time, the wireless communication signal processor 230 generates a signal by encoding according to the wireless communication technique used, and transmits the generated signal through the antenna 210. In this case, the wireless communication technique may be various communication methods such as Bluetooth, Wi-Fi.
이러한, 무선통신신호 처리부(230)는 신호를 생성하여 안테나(210)를 통해 송신하므로, 신호 생성에 필요한 부호화부(미도시), ADC(미도시) 등의 다양한 구성이 포함될 수 있다. Since the wireless communication signal processor 230 generates a signal and transmits the signal through the antenna 210, various components such as an encoder (not shown) and an ADC (not shown) required for signal generation may be included.
후방산란 통신 신호 처리부(240)는 안테나(210)를 통해 1차 사용자 장치로부터 수신한 RF 신호의 반사를 이용하여 신호(패킷)를 전송할 수 있다. 즉, 후방산란 통신 신호 처리부(240)는 1차 사용자 장치로부터 수신한 RF 신호를 반사하여 '1'을 전송, RF 신호를 반사하지 않으면 '0'을 전송할 수 있고, 이와 반대의 경우도 가능하다. The backscatter communication signal processor 240 may transmit a signal (packet) using the reflection of the RF signal received from the primary user device through the antenna 210. That is, the backscatter communication signal processor 240 transmits '1' by reflecting the RF signal received from the primary user device, and transmits '0' if the RF signal is not reflected, or vice versa. .
이러한 후방산란 통신 신호 처리부(240)는 무선통신 신호 처리부(230)와 달리 신호를 생성하는 것이 아니라, RF 신호의 반사를 이용하여 패킷을 전송할 수 있다. Unlike the wireless communication signal processor 230, the backscattered communication signal processor 240 may transmit a packet using reflection of an RF signal, rather than generating a signal.
에너지 수집부(250)는 1차 사용자 장치로부터의 RF 신호를 수신하여 전력 에너지를 생성하는 장치이다. 즉, 에너지 수집부(250)는 1차 사용자 장치로부터의 RF 신호를 안테나(210)를 통해 수신하고, 이를 일정한 직류 전류로 변환하여 배터리(미도시)를 충전한다. 이러한 에너지 수집부(250)는 안테나(210)에서 수신한 RF 신호의 전력 손실을 제거하는 임피던스 매칭 회로(미도시), 임피던스 매칭 회로의 출력 RF 신호를 직류 전류로 변환하는 전류 변환기(미도시) 등을 포함할 수 있다. The energy collector 250 is a device that generates power energy by receiving an RF signal from the primary user device. That is, the energy collector 250 receives the RF signal from the primary user device through the antenna 210 and converts it into a constant direct current to charge a battery (not shown). The energy collector 250 includes an impedance matching circuit (not shown) for removing power loss of the RF signal received from the antenna 210 and a current converter (not shown) for converting an output RF signal of the impedance matching circuit into a direct current. And the like.
이하, 본 발명에 따른 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능에 설명하기로 한다. Monte-Carlo 모의실험을 통해 2차 사용자의 패킷 전송 성능을 검증하였으며, 모든 에너지 레벨에서 정적 확률로 후방산란을 수행하는 경우 (
Figure PCTKR2018016876-appb-I000065
)와의 성능을 비교하였다. 모의실험을 위해 T=100 ms,
Figure PCTKR2018016876-appb-I000066
=2 ms, f= 1 MHz,
Figure PCTKR2018016876-appb-I000067
=1,
Figure PCTKR2018016876-appb-I000068
=-10 dB, L=5를 고려하였다.Hereinafter, packet transmission performance of a secondary user in a cognitive wireless network according to the present invention will be described. Monte-Carlo simulations verify the packet transmission performance of the secondary user and perform backscattering with static probability at all energy levels (
Figure PCTKR2018016876-appb-I000065
) And performance. T = 100 ms, for simulation
Figure PCTKR2018016876-appb-I000066
= 2 ms, f = 1 MHz,
Figure PCTKR2018016876-appb-I000067
= 1,
Figure PCTKR2018016876-appb-I000068
= -10 dB, L = 5 are considered.
도 8은 본 발명의 일 실시예에 따른 채널 상태 전이확률
Figure PCTKR2018016876-appb-I000069
에 따라 변화하는 2차 사용자 장치의 패킷 전송 성능을 나타낸 도면이다.8 is a channel state transition probability according to an embodiment of the present invention.
Figure PCTKR2018016876-appb-I000069
Is a diagram illustrating packet transmission performance of a secondary user device that varies with time.
도 8을 참조하면,
Figure PCTKR2018016876-appb-I000070
가 증가할수록 채널이 1차 사용자 장치에 의해 빈번하게 점유되어 2차 사용자 장치의 데이터 전송 기회는 감소하기 때문에 패킷 전송 성능은 저하된다. 하지만 주변 후방산란 통신 기능을 고려하였기 때문에,
Figure PCTKR2018016876-appb-I000071
가 증가하여도 후방산란을 통한 데이터 전송이 가능하여 2차 사용자 장치의 패킷 전송 성능이 계속하여 증가하는 것을 확인할 수 있다. 특히 본 발명과 같이 2차 사용자 장치가 에너지 레벨을 고려하여 동적 확률로 후방산란을 수행할 경우, 에너지가 충분하면 후방산란을 우선적으로 수행하기 때문에 높은 패킷 전송 성능을 얻을 수 있음을 알 수 있다.Referring to FIG. 8,
Figure PCTKR2018016876-appb-I000070
As is increased, the packet transmission performance is degraded because the channel is frequently occupied by the primary user equipment, thereby decreasing the data transmission opportunity of the secondary user equipment. However, because we considered the surrounding backscatter communication function,
Figure PCTKR2018016876-appb-I000071
It can be seen that even if is increased, the data transmission through the backscatter is possible, so that the packet transmission performance of the secondary user device continues to increase. In particular, when the secondary user device performs the backscattering with the dynamic probability in consideration of the energy level, it can be seen that high packet transmission performance can be obtained because the backscattering is preferentially performed when the energy is sufficient.
이상의 설명은 본 발명의 기술 사상을 예시적으로 설명한 것에 불과한 것으로, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 사람이라면 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 다양한 수정 및 변형이 가능할 것이다. 따라서, 본 발명에 개시된 실시예들은 본 발명의 기술 사상을 한정하기 위한 것이 아니라 설명하기 위한 것이고, 이러한 실시예에 의하여 본 발명의 기술 사상의 범위가 한정되는 것은 아니다. 본 발명의 보호 범위는 아래의 청구범위에 의하여 해석되어야 하며, 그와 동등한 범위 내에 있는 모든 기술 사상은 본 발명의 권리범위에 포함되는 것으로 해석되어야 할 것이다.The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (10)

  1. 인지 무선 네트워크에서 2차 사용자 장치의 패킷 전송 성능 개선을 위한 방법에 있어서, A method for improving packet transmission performance of a secondary user device in a cognitive wireless network,
    상기 2차 사용자 장치는, 스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단하는 단계;Determining, by the secondary user device, a channel occupancy state of the primary user device by spectrum sensing;
    상기 2차 사용자 장치는, 1차 사용자 장치에 의해 점유된 채널에 접근한 경우, 에너지 레벨에 기초하여 후방산란 모드 또는 에너지 수집 모드의 동작모드를 결정하는 단계; 및The secondary user device, when approaching a channel occupied by the primary user device, determines an operation mode of the backscattering mode or the energy collection mode based on the energy level; And
    상기 2차 사용자 장치는 상기 결정된 동작모드에 따라 동작하는 단계The second user device operating in accordance with the determined operation mode
    를 포함하는, 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.The packet transmission performance improvement method of a secondary user in a cognitive wireless network comprising a.
  2. 제1항에 있어서, The method of claim 1,
    상기 채널 점유 상태를 판단하는 단계는, Determining the channel occupation state,
    슬롯의 시작점에서 일정 시간동안 샘플링 주파수로 에너지 검출을 수행하여 채널의 점유 상태를 판단하는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.A method for improving packet transmission performance of a secondary user in a cognitive wireless network, characterized in that energy is detected by a sampling frequency at a start point of a slot for determining a channel occupancy state.
  3. 제1항에 있어서,The method of claim 1,
    상기 동작모드를 결정하는 단계는,Determining the operation mode,
    상기 에너지 레벨에 따른 후방산란 확률을 산출하는 단계; Calculating a backscattering probability according to the energy level;
    '0'부터 '1'사이의 크기를 갖는 랜덤값을 선택하고, 상기 선택된 랜덤값과 후방산란 확률 값을 비교하는 단계; 및 Selecting a random value having a size between '0' and '1' and comparing the selected random value with a backscatter probability value; And
    상기 랜덤 값이 후방산란 확률 값 이하인 경우 후방산란 모드로 결정하고, 후방산란 확률 값 이하가 아닌 경우 에너지 수집 모드로 결정하는 단계를 포함하는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.And determining the backscattering mode when the random value is less than or equal to the backscattering probability value and determining the energy collection mode when the random value is less than or equal to the backscattering probability value. How to improve.
  4. 제3항에 있어서,The method of claim 3,
    상기 에너지 레벨에 따른 후방산란 확률(
    Figure PCTKR2018016876-appb-I000072
    )은 아래 수학식으로 산출되는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.    Backscatter probability according to the energy level (
    Figure PCTKR2018016876-appb-I000072
    ) Is a method of improving packet transmission performance of a secondary user in a cognitive wireless network, characterized in that calculated by the following equation.
    [수학식][Equation]
    Figure PCTKR2018016876-appb-I000073
    Figure PCTKR2018016876-appb-I000073
    여기서, l은 2차 사용자 장치의 에너지 레벨, L은 에너지 최대 레벨,
    Figure PCTKR2018016876-appb-I000074
    은 슬롯 m에서의 채널 센싱 결과를 의미함.    Where l is the energy level of the secondary user device, L is the energy maximum level,
    Figure PCTKR2018016876-appb-I000074
    Denotes the result of channel sensing in slot m.
  5. 제1항에 있어서,The method of claim 1,
    상기 동작하는 단계는, The operation step,
    상기 결정된 동작모드가 후방산란 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 반사하여 패킷을 전송하고, When the determined operation mode is a backscattering mode, transmits a packet by reflecting an RF signal from the primary user device,
    상기 결정된 동작모드가 에너지 수집 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 이용하여 에너지 하베스팅을 수행하는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.And performing energy harvesting using the RF signal from the primary user device when the determined operation mode is the energy collection mode.
  6. 제1항에 있어서,The method of claim 1,
    상기 2차 사용자 장치는 1차 사용자 장치에 의해 점유되지 않은 채널에 접근한 경우, 무선 전송 방식으로 패킷을 전송하는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.And the second user device transmits a packet by a wireless transmission method when the second user device approaches a channel not occupied by the first user device.
  7. 제6항에 있어서,The method of claim 6,
    상기 2차 사용자 장치는 후방산란 모드 또는 무선전송 방식으로 패킷을 전송하고, 패킷 전송 성능(R)은 아래 수학식으로 정의되는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.The secondary user device transmits a packet in a backscattering mode or a wireless transmission method, and the packet transmission performance (R) is defined by the following equation.
    [수학식][Equation]
    Figure PCTKR2018016876-appb-I000075
    Figure PCTKR2018016876-appb-I000075
    여기서,
    Figure PCTKR2018016876-appb-I000076
    은 에너지 레벨
    Figure PCTKR2018016876-appb-I000077
    이 발생할 확률,
    Figure PCTKR2018016876-appb-I000078
    은 슬롯 m에서의 채널 센싱 결과,
    Figure PCTKR2018016876-appb-I000079
    은 슬롯 m에서의 채널 점유 상태,
    Figure PCTKR2018016876-appb-I000080
    은 무선전송 방식으로 1차 사용자 장치와의 충돌없이 패킷을 전송할 확률,
    Figure PCTKR2018016876-appb-I000081
    은 후방산란 모드로 패킷을 전송할 확률,
    Figure PCTKR2018016876-appb-I000082
    은 후방산란 확률을 의미함.    here,
    Figure PCTKR2018016876-appb-I000076
    Silver energy level
    Figure PCTKR2018016876-appb-I000077
    Probability of this occurring,
    Figure PCTKR2018016876-appb-I000078
    Is the channel sensing result in slot m,
    Figure PCTKR2018016876-appb-I000079
    Is the channel occupancy state in slot m,
    Figure PCTKR2018016876-appb-I000080
    Is the probability of transmitting a packet without collision with a primary user device through a wireless transmission method,
    Figure PCTKR2018016876-appb-I000081
    Is the probability of sending a packet in backscattering mode,
    Figure PCTKR2018016876-appb-I000082
    Is the probability of backscattering.
  8. 제7항에 있어서,The method of claim 7, wherein
    상기 에너지 레벨 l이 발생할 확률(
    Figure PCTKR2018016876-appb-I000083
    )은 에너지 레벨 전이 확률을 고려한 아래 수학식에 의해 정의되는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자의 패킷 전송 성능 개선 방법.    The probability that the energy level l will occur (
    Figure PCTKR2018016876-appb-I000083
    ) Is defined by the following equation taking into account the energy level transition probability, the packet transmission performance improvement method of the secondary user in a cognitive wireless network.
    [수학식][Equation]
    Figure PCTKR2018016876-appb-I000084
    Figure PCTKR2018016876-appb-I000084
    여기서,
    Figure PCTKR2018016876-appb-I000085
    ,
    Figure PCTKR2018016876-appb-I000086
    , Pc는 에너지를 소모할 확률로
    Figure PCTKR2018016876-appb-I000087
    , Pd는 검출 확률을 의미함.    here,
    Figure PCTKR2018016876-appb-I000085
    ,
    Figure PCTKR2018016876-appb-I000086
    , Pc is the probability of consuming energy
    Figure PCTKR2018016876-appb-I000087
    , Pd means the detection probability.
  9. 인지 무선 네트워크에서 패킷 전송 성능 개선을 위한 2차 사용자 장치에 있어서, A secondary user device for improving packet transmission performance in a cognitive wireless network,
    스펙트럼 센싱으로 1차 사용자 장치의 채널 점유 상태를 판단하고, 1차 사용자 장치에 의해 점유된 채널에 접근한 경우, 에너지 레벨에 기초하여 후방산란 모드 또는 에너지 수집 모드의 동작모드를 결정하는 제어부;A controller for determining a channel occupancy state of the primary user device by spectrum sensing and determining an operation mode of the backscattering mode or the energy collection mode based on the energy level when the channel occupied by the primary user device is approached;
    상기 제어부에서 결정된 동작모드가 후방산란 모드인 경우, 1차 사용자 장치로부터 수신한 RF 신호의 반사를 이용하여 패킷을 전송하는 후방산란 통신 신호 처리부;A backscatter communication signal processor for transmitting a packet by using the reflection of the RF signal received from the primary user device when the operation mode determined by the controller is the backscattering mode;
    상기 제어부에서 결정된 동작 모드가 에너지 수집 모드인 경우, 상기 1차 사용자 장치로부터의 RF 신호를 이용하여 에너지 하베스팅을 수행하는 에너지 수집부When the operation mode determined by the control unit is the energy collection mode, the energy collection unit for performing energy harvesting using the RF signal from the primary user device
    를 포함하는 인지 무선 네트워크에서 2차 사용자 장치.Secondary user device in a cognitive wireless network comprising a.
  10. 제9항에 있어서, The method of claim 9,
    상기 1차 사용자 장치에 의해 점유되지 않은 채널에 접근한 경우, 무선 전송 방식으로 패킷을 전송하는 무선통신 신호 처리부를 더 포함하는 것을 특징으로 하는 인지 무선 네트워크에서 2차 사용자 장치.And a wireless communication signal processing unit for transmitting a packet by a wireless transmission method when a channel not occupied by the primary user device is accessed.
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