KR100938685B1 - Wireless communication system, and transmitting power and bandwidth allocation method thereof - Google Patents

Abstract

The present invention discloses a wireless communication system and its bandwidth and transmission power allocation method. The present invention utilizes a main user device that transmits and receives data with a licensed bandwidth and an interference temperature limit that uses the licensed and unlicensed bandwidths and that does not interfere with the communication of the main user device, and which is intended to be used. The interference temperature is calculated by increasing the bandwidth from the frequency, and the communication capacity is calculated using the allocated temperature minus the interference temperature, and when the calculated communication capacity satisfies the set communication capacity, And a CR user device that obtains CR power using the bandwidth and transmits and receives data using the bandwidth and the CR power within a range not exceeding the interference temperature limit.

Therefore, the wireless communication system of the present invention and its bandwidth and transmission power allocation method do not use the bandwidth including the bandwidth used by the main user, as long as it does not set the interference temperature limit and does not interfere with the main user by using the interference temperature. By allocating bandwidth and transmission power to satisfy the communication capacity and performance required by the user whether it is wireless or not, the user coexists and communicates without interfering with the main user and the wireless user, thereby efficiently using limited frequency resources.

Description

Wireless communication system and its bandwidth and transmission power allocation method {Wireless communication system, and transmitting power and bandwidth allocation method}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system and a method for allocating bandwidth and transmission power thereof, and more particularly, to a system in which a user allocates bandwidth and transmission power and communicates to a bandwidth used by an authorized user using the concept of interference temperature. It is about a method.

With the rapid development of wireless communication systems and the emergence of various services, the demand for wireless resources is increasing day by day, but due to the allocation of almost all commercially available frequency bands, there is a very shortage of frequency resources for new wireless platforms. . In order to solve the problem of frequency shortage, a CR communication system based on a wireless recognition (CR) scheme has been proposed.

CR is a technology that automatically finds unused frequencies according to region and time, and protects licensed radio stations around it so that they can communicate with each other. It is possible to increase the efficiency of the limited resource frequency by determining and reusing the frequency bandwidth, output, and modulation method for the environment.

Since the possibility of frequency common use has been mentioned, much attention and research has been conducted on intelligent CR technology, and the concept of interference temperature, which quantifies and manages the amount of interference so that the wireless device can be used in the band of the main user, Known.

Interference temperature is the temperature of the radio frequency (RF) power emitted from other transmitters and noise sources and measured at the receiving antenna of the receiver. It is the temperature equivalent to the RF power of the receiving antenna per unit bandwidth. Display. The concept of the interference temperature of the receiver is proposed by the Federal Communications Commission (FCC) as a way to reflect the environment on the receiver side after the transmitter to regulate the efficiency of frequency use. It is based.

The interference temperature includes all noise signals and interference signals such as thermal noise, interchannel interference, adjacent channel interference, and internal / external cell interference, and can be derived by obtaining thermal noise, and the power received from the antenna is equal to Boltzmann constant. It can be calculated by dividing by the RF bandwidth (Hz).

Using the concept of interference temperature, after the spectrum sensing, the interference temperature is divided into an ideal interference temperature model and a general interference temperature model according to the main user's signal, interference and noise, and the frequency band used by the main user is specified. Although the interference temperature multiple access technology has been proposed to allow a large number of CR users to be used only below the interference temperature limit for other wireless communication purposes, the research on interference temperature multiple access technology has been conducted under the radio resource environment that is insufficient in the wireless communication field. There are still few studies on excellent methods for coexistence of users and CR users, or cases and specific processing methods that can be applied to the actual environment.

1 is a diagram schematically showing the structure of a conventional radiocognitive communication system, which includes a main user base station 1, a main user 11, a CR user base station 5, and a CR user 15. As shown in FIG.

1 illustrates a wireless cognitive communication system as follows.

First, the CR communication system has a predetermined cell 10 structure, and a main system and a main system having a right to use a predetermined frequency band in a predetermined cell 10 do not use the predetermined frequency band. It includes a sub-system that does not have a right to use a predetermined frequency band but can use the predetermined frequency band.

The main system includes a main user base station 1 and a main user 11 receiving communication service from the main user base station 1, and a frequency band in which the main system has a right to use is referred to as a first frequency band, The secondary system includes a CR user base station 5 and a CR user 15 provided with a communication service from the CR user base station 5, and the second frequency band uses a frequency band that is not actually used by the main system in the first frequency band. It is called.

The main user base station 1 of the main system provides current location information and channel state information of the main user from the main user 11 while providing the communication service to the main user 11 through a predetermined frequency band; Receive CSI) feedback. At this time, the CR user 15 of the secondary system measures interference information according to its communication environment, for example, noise and interference conditions, so that a channel not occupied at the current location where the current system exists, that is, the primary system has a right to use it. A channel not used by the main user base station 1 and the main user 11 of the main system in the first frequency band is selected.

The CR user 15 of the secondary system searches for a channel to be searched by the CR user 15 itself in the first frequency band to which the primary system has authority from the CR user base station 5, that is, the secondary system searches for the first frequency band. Receive a selectable band. Here, the CR user base station 5 of the secondary system knows in advance the frequency band selectable in the first frequency band, that is, the CR user channel, through communication with the main user base station 1 of the main system.

Upon receiving the CR user channel to be searched from the CR user base station 5, the CR user 15 checks whether a signal exists in the CR user channel to be searched. Here, checking whether there is a signal in the CR user channel indicates whether a signal received by the CR user 15 is transmitted or received by the main system or an interference signal, for example, whether it is another radio signal or transmitted or received by the system. Check it. At this time, the CR user 15 compares the strength of the signal measured in the CR user channel with a threshold set by the user or wireless communication system corresponding to the communication environment.

As a result of the comparison, when the measured signal strength is smaller than the threshold value, the CR user 15 selects the CR user channel and detects the available frequency band, that is, the second frequency band, and detects the detection result of the CR user base station 5. To send. Then, the CR user base station 5 allocates resources of the second frequency band so that the sub-system can transmit and receive data through the second frequency band. On the other hand, as a result of the comparison, if the measured signal strength is greater than the threshold value, the CR user 15 detects the CR user channel as an unusable frequency band because it is used by the main system or another sub-system, and detects the detection result as a CR user. Transmit to base station 5. Then, the CR user base station 5 causes the CR user 15 to search for a CR user channel different from the CR user channel in the first frequency band because the secondary system cannot use the frequency band of the CR user channel.

FIG. 2 is a flowchart illustrating an operation process of a CR user of a sub system in the radiocognitive communication system of FIG.

The flowchart of FIG. 2 will be described with reference to FIG. 1.

The CR user 15 receives from the CR user base station 5 a frequency band selectable from the first frequency band to which the main system has authority in the CR communication system, and searches for and selects the received CR user channel. S1)

The average power R of any K th symbols Rk among the symbols present in the found CR user channel is measured (step S3).

Then, when the number of all symbols of the CR user channel is M using the measured average power R, the average power D1 of the symbol is calculated in a section having M symbols (step S5).

A power Fourn transform of the arbitrary Kth symbol Rk into a point of N-FFT (FFT: Fast Fourier Transform, hereinafter referred to as 'FFT') to calculate a power Fn of an arbitrary Nth point, and calculating The power of the pilot signal, that is, the power P1 of the DC point, which is the first point, is calculated from the signal received at the CR user channel through the power Fn of one arbitrary N-th point.

Here, N-FFT means FFT size.

In addition, the signal received from the CR user channel calculates the strength of the signal excluding the pilot signal, that is, the average power P2 of the remaining points excluding the DC point. When the power P1 of the first point DC and the power P2 of the remaining points except the first point are calculated, the power ratio between the two powers calculated, that is, the power P1 of the DC point and the power P2 of the remaining points except the DC point, is calculated. Calculate. That is, the power ratio D2 of the pilot signal in the CR user channel and the remaining signals except for the pilot signal is calculated (step S7).

Comparing the average power D1 in all symbol periods of the CR user channel with the first threshold value G1 (step S9), it is checked whether there is a signal in the CR user channel, and the average power D1 in all symbol periods of the CR user channel. As a result of the comparison with the first threshold value G1, when D1 is greater than the first threshold value G1, it is confirmed that a signal exists in the CR user channel.

As a result of the check, if a signal exists in the CR user channel, the process proceeds to step S11, and compares the power ratio D2 and the second threshold value G2 of the signals other than the pilot signal and the pilot signal in the CR user channel (step S11). Corresponding to the comparison result, a signal existing in the CR user channel, that is, a signal received by the CR user 15 is confirmed to be a signal transmitted and received by the main system (step S13), or a signal received by the CR user 15. Is an interference signal, for example, a signal transmitted / received by another sub system (step S15).

Here, the first threshold value and the second threshold value are thresholds set by the user or the CR communication system corresponding to the communication environment.

As a result of the comparison in step S11, if D2 is greater than the second threshold value G2, the signal strength of the pilot signal among the signals existing in the CR user channel is greater than the remaining signals except for the pilot signal, and the flow proceeds to step S13. Confirm that the signal present in the CR user channel is the main system signal.

As a result of the comparison in step S11, if the power ratio D2 of the signal is smaller than the second threshold value G2, the signal strength of the pilot signal among the signals existing in the CR user channel is smaller than the remaining signals except for the pilot signal. Proceeding to S15, it is confirmed that the signal present in the CR user channel is an interference signal, for example, another sub system signal.

As a result of comparing the average power D1 and the first threshold value G1 in all symbol periods of the CR user channel in step S9, when D1 is smaller than the first threshold value G1, it is determined that no signal exists in the CR user channel. . In other words, if it is determined in step S9 that no signal exists in the CR user channel, the process proceeds to step S17, and the power ratio D2 of the remaining signals excluding the pilot signal and the pilot signal in the CR user channel is compared with the second threshold value G2. (Step S17)

As a result of the comparison in step S17, if the power ratio D2 of the signal is smaller than the second threshold G2, the CR user channel is selected and detected as an available frequency band, that is, the second frequency band, and the detection result for the second frequency band. Is transmitted to the primary user base station (5) to receive the resource of the second frequency band and transmit and receive data.

As a result of the comparison in step S17, if D2 is greater than the second threshold value, it is determined that the detection of the received signal is an error and the process proceeds to step S3, and the average power of any K-th received symbol Rk in the signal received in step S3. Measure R again.

As a result, as a result of the comparison between the average power D1 and the first threshold value, if D1 is less than the first threshold value, it is confirmed that no signal exists in the CR user channel, whereas, as a result of the comparison, D1 is the first threshold value. If greater, it is confirmed that a signal exists in the CR user channel.

If no signal is present in the CR user channel, the second frequency band is compared with the power ratio D2 of the remaining signals excluding the pilot signal and the pilot signal and the second threshold in the CR user channel, and if D2 is smaller than the second threshold. And transmit to the CR user base station 5 to transmit and receive data through the second frequency band. If the comparison result D2 is greater than the second threshold value, it is determined that the detection of the received signal is an error, and the average power of any K-th received symbol is measured again.

If a signal exists in the CR user channel, it is checked whether the signal existing in the CR user channel is a signal by comparing the power ratio D2 of the remaining signals except for the pilot signal and the pilot signal with the second threshold value. As a result of the comparison, when D2 is greater than the second threshold, it is confirmed that the signal present in the CR user channel is a signal transmitted and received by the main system. As a result of the comparison, when D2 is smaller than the second threshold, it is confirmed that the signal present in the CR user channel is a signal transmitted and received by another sub system.

As described above, the conventional radiocognitive communication system selects a channel not used by the main user base station and the main user of the main system in the first frequency band in which the main system has a right to use.

It is an object of the present invention to provide a system in which an unlicensed band including a licensed main user's band can coexist while satisfying a required communication capacity with each other without interfering with each other.

It is another object of the present invention to provide a user with a bandwidth and a wireless license so that the main user and the wireless user can coexist while satisfying the required communication capacity without interfering with each other in the unlicensed band including the band of the licensed main user. It is to provide a method for allocating transmission power.

A wireless communication system of the present invention for achieving the above object uses a main user device for transmitting and receiving data with a licensed bandwidth, and utilizes the licensed bandwidth and the unlicensed bandwidth and does not interfere with the communication of the main user device. Determine the interference temperature limit, and increase the bandwidth from the center frequency to be used, calculate the interference temperature according to [Equation 1] below, and calculate the communication capacity using the assigned temperature minus the interference temperature from the interference temperature limit value. If the calculated communication capacity satisfies the set communication capacity, the bandwidth is designated as the CR bandwidth, CR power is calculated using the assigned temperature and the CR bandwidth, and the CR is within the range not exceeding the interference temperature limit. And a CR user device configured to transmit and receive data using a bandwidth and the CR power. It is characterized by.

A main user device of the present invention for achieving the above object comprises a main user transmitter for transmitting data using the licensed bandwidth and a main user receiver for receiving data of the main user transmitter, using the established protocol. Receiving data of the CR user device, and outputs the data in response to the received data.

The main user receiver of the present invention for achieving the above object is a receiver for receiving the data of the main user transmitter and the data of the CR user device, a spectrum sensing unit for searching for the available bandwidth and the spectrum sensing and outputting the spectrum data; A data processor for signal processing data of the main user transmitter and outputting the spectral data and the required first signal-to-noise ratio in response to data of the CR user device, and outputting the spectral data and the first signal-to-noise ratio as RF signals It characterized by comprising a transmitting unit.

The CR user device of the present invention for achieving the above object transmits and receives data of the main user device using the protocol, and the data and the required second signal to noise ratio, the CR frequency and the CR using the center frequency A CR user transmitter for allocating power and a CR user receiver for communicating with the CR user transmitter using the CR bandwidth and the CR power.

The CR user transmitter of the present invention for achieving the above object is to perform the interference temperature modeling using the spectral data, the receiver for receiving the spectral data and the first signal-to-noise ratio, to set the interference temperature limit, The interference temperature is calculated using the center frequency, the bandwidth and spectrum data while increasing the bandwidth from the center frequency, and the allocation temperature is calculated by calculating the allocation temperature by subtracting the interference temperature from the interference temperature limit. The communication capacity is calculated using the bandwidth, the spectrum data, and the path loss. When the communication capacity satisfies the communication capacity of the CR user device, the CR bandwidth for minimizing the difference between the calculated communication capacity and the set communication capacity is calculated. And the CR bandwidth and the assigned temperature A data processor which calculates the CR power using the path loss and allocates the bandwidth and the CR power by checking whether the CR power satisfies the performance of the main user receiver and the CR user receiver, and the CR bandwidth and And a transmitter for outputting data as an RF signal using the CR power.

Bandwidth and transmission power allocation method of the wireless communication system of the present invention for achieving the above another object is to determine the interference temperature limit does not interfere with the communication of the main user receiver according to the spectrum data, the center frequency to be used in the CR user transmitter Computing an interference temperature according to the following [Equation 2] while increasing the bandwidth from, calculates the allocated temperature using the interference temperature limit and the interference temperature, the communication capacity calculation step of calculating the communication capacity using the assigned temperature, the If the calculated communication capacity satisfies the set communication capacity, the bandwidth satisfying the communication capacity is designated as the CR bandwidth, and the CR power is calculated using the assigned temperature and the CR bandwidth. CR power calculation and performance check stage to check the performance of the main user receiver , And it is characterized in that it comprises an acknowledgment and a communication step of communicating by allocating bandwidth and the CR CR CR power if the bandwidth and the CR ensure that power to meet the performance of the CR user receiver, and satisfaction.

The communication capacity calculation step of the present invention for achieving the another object is a spectrum sensing step of outputting the spectrum data generated by the spectrum sensing of the searchable bandwidth in the main user receiver, the spectrum data and the required in the main user receiver A spectrum information transmission step of transmitting a first signal-to-noise ratio to the CR user transmitter, and modeling the interference temperature using the spectrum data, setting the interference temperature limit value, and setting the interference temperature and the communication capacity of the CR user transmitter. And setting and calculating steps to calculate.

In the setting and calculating step of the present invention for achieving the another object, the interference temperature modeling step using the spectral data, and the interference temperature modeling step of setting the interference temperature limit using the spectral data and the first signal-to-noise ratio, Increasing the bandwidth from the center frequency while integrating the power spectral density of the spectrum data divided by the bandwidth to obtain the average interference power, the interference temperature calculation using the average interference power, the center frequency, the bandwidth to calculate the interference temperature And using the allocation temperature and bandwidth minus the interference temperature from the interference temperature limit, the noise power of the spectrum data, and the path loss between the main user receiver and the CR user transmitter, the CR user transmitter, and the CR user receiver. Calculate the communication capacity And a CR communication capacity calculating step.

In the interference temperature modeling of the present invention for achieving the above object, when the signals of the main user receiver are separated from the interference and noise signals by analyzing the spectral data, the ideal interference temperature modeling is performed according to Equation 3 below. If the signals of the main user receiver are not distinguished from the interference and noise signals, general interference temperature modeling is performed according to Equation 4 below.

CR power calculation and performance verification step of the present invention to achieve the other object
Comparing the communication capacity and the required communication capacity required for the CR user receiver, if the communication capacity is less than the required communication capacity communication capacity comparison step to perform again from the interference temperature calculation step, in the communication capacity comparison step If the communication capacity is greater than or equal to the required communication capacity, a bandwidth for minimizing the difference between the calculated communication capacity and the required communication capacity is set using an optimization algorithm, and the allocation temperature, the bandwidth, and the path loss are used. A bandwidth and CR power setting step of calculating CR power, and a CR power adjustment step of checking whether the bandwidth and the CR power satisfy the performance required for the main user receiver, and lowering the CR power if the performance is not satisfied. Characterized in that.

The CR power adjustment step of the present invention for achieving the other object is to calculate the signal-to-noise ratio of the main user receiver using the spectral data, the CR power, the path loss, the calculated signal-to-noise ratio is the first signal band A performance checking step of comparing whether the noise ratio is satisfied, a bandwidth and CR power allocating step of allocating the bandwidth and the CR power to the CR user transmitter if the performance checking step is satisfied; and
If the performance check step is not satisfied, the CR power is lowered and the CR power is increased in another band of the CR user transmitter by the lowered CR power, and the interference temperature due to the raised CR power does not exceed the interference temperature limit. And adjusting the band-by-band adjustment step.

In the band-specific adjustment step of the present invention to achieve the other object, if the performance verification step is not satisfied, the CR power is lowered and the spectral data, the lower CR power, and the path loss of the main user receiver are used. Calculating a signal-to-noise ratio, comparing the calculated signal-to-noise ratio with the first signal-to-noise ratio, and if not satisfied, lowering the CR power until it satisfies; a different band of the CR user transmitter by the lowered CR power In the transmission power compensation step of raising the CR power, and calculates the interference temperature in the other band of the raised CR power, and if the interference temperature limit is exceeded, if the interference temperature limit is exceeded and starts again from the interference temperature calculation step Bandwidth and CR power allocation stage if the interference temperature limit is not exceeded. And another band identification step for executing the system.

The acknowledgment and communication step of the present invention for achieving the other object is to obtain the transmit power of the main user transmitter from the receive power of the main user receiver, and the transmit power of the main user transmitter and the main user transmitter and the CR user receiver Calculate the transmission noise power of the CR user receiver by using the path loss between the two, calculate the total noise power by adding the transmission noise power of the CR user receiver and the noise power when there is no signal of the CR user receiver, and the total noise power. And a CR user performance checking step of calculating a signal-to-noise ratio of the CR user receiver using the CR power, comparing the second signal-to-noise ratio required by the CR user receiver, and verifying that the CR user performance is satisfied. If not satisfied, start again from the interference temperature calculation step, If the CR user performance check step is satisfied, characterized in that it comprises a determination and communication step of communicating by using the bandwidth and the CR power.

Therefore, the wireless communication system of the present invention and its bandwidth and transmission power allocation method do not use the bandwidth including the bandwidth used by the main user, as long as it does not set the interference temperature limit and does not interfere with the main user by using the interference temperature. By allocating bandwidth and transmission power to satisfy the communication capacity and performance required by the user whether it is wireless or not, the user coexists and communicates without interfering with the main user and the wireless user, thereby efficiently using limited frequency resources.

Hereinafter, a wireless communication system and a bandwidth and a transmission power allocation method thereof according to the present invention will be described with reference to the accompanying drawings.

3 is a diagram illustrating a schematic structure of a communication system according to the present invention, and includes a main user transmitter 100, a main user receiver 101, a CR user transmitter 200, and a CR user receiver 201.

The main user transmitter 100 communicates with the main user receiver 101 with a licensed bandwidth. K is the path loss until the signal of the main user transmitter 100 reaches the main user receiver 101. The signal of the main user transmitter 100 also affects the CR user receiver 201, where N is the path loss until the signal of the main user transmitter 100 arrives at the CR user receiver 201.

The main user receiver 101 communicates with the main user transmitter 100, spectrum senses a receivable bandwidth, obtains received power and noise power using the generated spectrum data, and CR with the required signal-to-noise ratio. The data is output in response to the data request signal of the user transmitter 200.

Here, the CR user apparatuses 200 and 201 and the main user apparatuses 100 and 101 each include a transmitter and a receiver, and transmit and receive data by embedding a preset protocol.

The CR user transmitter 200 communicates with the CR user receiver 201, sends a signal requesting data to the main user receiver 101, and receives the received power, noise power, and required signal-to-noise ratio of the main user receiver 101. Receive.

In addition, the CR user transmitter 200 uses the reception power, the noise power, the required signal-to-noise ratio of the main user receiver 101, the signal-to-noise ratio required by the CR user receiver 201, and the center frequency. ) And the interference temperature, and determine the bandwidth and transmission power of the CR user transmitter 200 using the interference temperature. After that, the bandwidth and transmission power of the determined CR user transmitter 200 are transmitted to the main user receiver 201 and the CR user receiver 201, and the performance (eg, required signal-to-noise ratio) required for each device is satisfied. Check it.

In this case, the signal of the CR user transmitter 200 also affects the main user receiver 101, and M is a path loss until the signal of the CR user transmitter 200 reaches the main user receiver 101.

The CR user receiver 201 communicates using the bandwidth and transmission power determined by the CR user transmitter 200. L is the path loss until the signal of CR user transmitter 200 arrives at CR user receiver 201.

Here, the CR user transmitter 200 models the interference temperature according to the communication environment using the spectrum data of the main user receiver 101 and calculates the interference temperature by using the center frequency to be used.

Here, the interference temperature can be obtained through Equation 1.

[Equation 1]

이고, 대역폭이 B인 대역 내의 간섭온도를 구할 수 있으며, B 대역폭 내의 평균간섭전력(

)을 볼츠만 상수(Boltzman's constant) k와 대역폭 B의 곱으로 나누어주면 B 대역폭의 간섭온도가 된다. 평균간섭전력(

)은 그 대역 구간 동안에 전력 스펙트럼 밀도(PSD: Power Spectral Density) S(f)를 적분하여 대역폭 B로 나누어 계산한다.Equation 1 is the center frequency

, The interference temperature in the band where the bandwidth is B, and the average interference power in the B bandwidth (

) Divided by the product of Boltzman's constant k and bandwidth B is the interference temperature of B bandwidth. Average interference power (

) Is calculated by integrating Power Spectral Density (PSD) S (f) during the band period and dividing by the bandwidth B.

In addition, the interference temperature limit should be set to satisfy the minimum quality of service (QoS) required for communication between the main user transmitter 100 and the main user receiver 101, and is a regulatory body such as the Federal Communications Commission (FCC). In this invention, the maximum noise power that the CR user transmitter 200 can tolerate using the received power received from the main user receiver 101, the noise power, and the required signal-to-noise ratio. The maximum allowable noise power is obtained by dividing the Boltzmann constant k by the product of the bandwidth B of the main user receiver 101 to determine the interference temperature limit.

4 is a diagram illustrating the configuration of the main user transmitter of FIG. 3 and includes a receiver 110, a spectrum sensor 130, a data processor 150, and a transmitter 170.

Referring to Fig. 3, the configuration and operation of the main user device of Fig. 4 will be described.

The receiver 110 receives a signal of the main user transmitter 100, receives a signal of the CR user transmitter 200 according to a set protocol, and a signal of the main user transmitter 100 and a signal of the CR user transmitter 200. Is output to the data processor 150.

The spectrum sensing unit 130 searches for a bandwidth that can be received by the main user receiver 101, performs spectrum sensing, and generates and outputs the spectrum data SP_SIG1 to the data processing unit 150.

The data processor 150 receives the signal output from the receiver 110, processes the signal, reflects the signal to the main user device 100, or outputs the signal through the transmitter 170. In response to the signal of the CR user transmitter 201, the signal-to-noise ratio required by the spectral signal SP_SIG1 and the main user receiver 101 is output.

The transmitter 170 outputs an applied signal as a radio frequency (RF) signal.

FIG. 5 is a diagram showing the configuration of the CR user transmitter of FIG. 3, which is composed of a receiver 210, a data processor 250, and a transmitter 270. As shown in FIG.

The configuration and operation of the CR user transmitter of FIG. 5 will now be described with reference to FIG. 3.

The receiver 210 communicates with the main user receiver 101 using a preset protocol, receives the spectra signal SP_SIG1 and the signal-to-noise ratio of the main user receiver 101, and outputs the signal to the data processor 250. .

When the signals of the main user are distinguished from the interference and noise signals by using the spectral signal SP_SIG1 of the main user receiver 101, the data processor 250 performs an ideal interference temperature modeling. If it is indistinguishable from the interference and noise signals, general interference temperature modeling is performed to determine the interference temperature limit according to the modeling, calculate the interference temperature, and determine the communication capacity according to the bandwidth. Equation 2 is a formula for calculating the communication capacity in the ideal interference temperature model, Equation 3 is a formula for obtaining the communication capacity in the general interference temperature model.

[Equation 2]

[Equation 3]

이고, 대역폭이 B인 이상적인 간섭온도 모델에서의 통신용량을 구한 것으로,

는 평균간섭전력을 나타내고,

은 CR 사용자 수신기에서의 수신전력을 나타내며,

는 CR 사용자 송신기에 허용할 수 있는 평균 최대 송신전력이다. 또한

는 간섭온도이고,

은 간섭온도 제한치 이다. Equations 2 and 3 have a center frequency

Is the communication capacity in the ideal interference temperature model with bandwidth B,

Represents the average interference power,

Denotes the received power at the CR user receiver,

Is the average maximum transmit power allowed for the CR user transmitter. Also

Is the interference temperature,

Is the interference temperature limit.

와 수신전력

의 합으로 표현할 수 있고, 괄호안의 분자 신호전력은 CR 사용자의 최대 송신전력에 CR 송수신기 사이의 경로 손실을 곱합 LP*로 표현할 수 있다.Since the communication capacity of Equation 2 should be calculated from the CR user receiver perspective, the denominator noise power in parentheses is the average interference power.

And received power

The molecular signal power in parentheses can be expressed as the sum LP * of the path loss between the CR transceiver and the maximum transmit power of the CR user.

)는 잡음전력을 대신한 온도로 표현한 것이고, 간섭온도 제한치()에서 간섭온도를 뺀 후, (L/M)을 곱해 줌으로써 신호전력을 대신하여 온도로 표현한 것이며, 이를 전력으로 표시해도 (P=kBT) 이런 관계가 있기 때문에 분모분자의 kB가 약분되어 상기 통신용량식의 SNR을 표현할 수 있다. 여기서

-

는 주 사용자 수신기(101) 관점에서 계산되어 M으로 나누어 줌으로써 CR 사용자의 송신전력을 계산할 수 있고, L을 곱해 줌으로써 CR 사용자 수신기(101)에서 수신전력을 알 수 있다.Communication capacity of Equation 3 is the interference temperature (

) Is the temperature instead of the noise power, and the interference temperature limit ( ) By subtracting the interference temperature and multiplying by (L / M) to express the temperature instead of the signal power, and even if it is expressed as power (P = kBT), this relationship is so weak that kB of the denominator is reduced. Capacitive SNR can be expressed. here

-

Calculated from the perspective of the main user receiver 101 and divided by M can calculate the transmission power of the CR user, and by multiplying L it can be seen the reception power in the CR user receiver (101).

)는 상기 수학식 1을 이용하여 구할 수 있고, 간섭온도(

)도 상기 수학식 1에서 구할 수 있는데, CR 사용자 송신기(200)에서 요구되는 신호대잡음비와 설정된 중심주파수를 이용하여 간섭온도를 계산한다.Here, after modeling the interference temperature in the CR transmitter, the reception power, noise power, etc. are calculated using the spectral signal SP_SIG of the main user receiver 101, and the calculated reception power, noise power and received signal-to-noise ratio are calculated. The interference temperature limit value is calculated using the interference temperature limit value (

) Can be obtained using Equation 1 above, and the interference temperature (

) Can also be obtained from Equation 1, using the signal-to-noise ratio required by the CR user transmitter 200 and the set center frequency to calculate the interference temperature.

The maximum assignable transmission of the CR user transmitter 201 using the communication capacity if the calculated communication capacity is greater than or equal to the required communication capacity compared to the calculated communication capacity and the communication capacity required by the CR user receiver 201. Calculate the power.

A method of allocating transmission power for each modeling method is described with reference to FIGS. 6 and 7.

Then, by calculating the interference power of the calculated transmission power to the main user receiver 101, the communication performance (e.g. SNR required for the main user receiver 101 to communicate with the main user transmitter 100 with the allowed bandwidth). ) And then communicate with the CR user receiver 201 with the calculated transmit power, and calculates the interference power that the signal of the main user transmitter 100 affects the CR user receiver 201 to calculate the CR user receiver 201. ), The communication performance (e.g. required SNR) is met.

The transmitter 270 outputs the applied data as an RF signal.

FIG. 6 is a graph illustrating a method of allocating transmission power of a CR user in the ideal interference temperature model of FIG. 5.

A method of allocating transmit power of a CR user of FIG. 6 will now be described.

를 중심으로 대역폭 B를 이용 시 그 대역 내에 주 사용자들이 1~N까지 N명의 주 사용자가 있을 때를 나타낸 그래프이다. CR user transmitter 200 is the center frequency

In the case of using bandwidth B, the graph shows when there are N main users from 1 to N in the band.

)와 간섭온도(

)를 구할 수 있다. 각 주사용자 대역의 간섭온도 제한치(

)에서 간섭온도(

)를 빼주어 CR 사용자에게 할당할 수 있는 온도(

)를 도출 할 수 있다After sensing the spectrum of the main user receiver 101 and receiving the sensing information and the minimum required signal-to-noise ratio information from the main user receiver 101, as shown in FIG.

) And interference temperature (

) Can be obtained. Interference temperature limit of each main user band (

At)

) To assign the CR user the temperature (

I can derive

)을 구할 수 있다.Knowing the temperature that can be assigned to the CR user, the transmit power (

) Can be obtained.

[Equation 4]

)에 kB를 곱해 줌으로써 전력으로 환산되고, M으로 나눠줌으로써 CR 사용자 송신기에서 송신할 수 있는 최대 전력이 된다. 각각의 주 사용자 대역에서 위와 같이 계산한 후 가장 작은 값을 이용하여 CR 사용자에게 송신전력으로 할당한다.Equation 4 is the temperature that can be assigned to the CR user (

) Is multiplied by kB to convert to power, and dividing by M gives the maximum power that can be transmitted by the CR user transmitter. Calculate as above in each main user band and assign it as transmit power to CR user using the smallest value.

)을 도6에 나타낸 것과 같을 때, 전 대역에서의 CR 사용자에게 할당 할 수 있는 전력(

)을 도6에 나타내었다.Here, the maximum power that can be allocated in the empty frequency band after spectrum sensing of the main user receiver 101 should be prescribed by a regulatory body managing the frequency, and the power value (

) Can be allocated to CR users in all bands when

) Is shown in FIG. 6.

FIG. 7 is a graph illustrating a method of allocating transmission power of a CR user in the general interference temperature model of FIG. 5.

A method of allocating a transmission power of a CR user of FIG. 7 will now be described.

After the spectral sensing of the main user receiver 101, if it is not possible to distinguish between the main user and noise and interference, all power sensed in a specific band is regarded as interference.

)가 정해지고 각 대역에서의 간섭온도(

)를 측정하면, CR 사용자에게 할당할 수 있는 온도(

)를 알 수 있으며, 수학식 5를 이용하여 각 대역에서 CR 사용자에게 할당할 수 있는 전력(

)을 구할 수 있다.In a typical interference temperature model, the interference temperature limit (

) And the interference temperature in each band (

), The temperature (which can be assigned to the CR user)

), And the power that can be allocated to the CR user in each band by using Equation 5

) Can be obtained.

[Equation 5]

)를 최대로 할당할 수 있는 전(

)으로 도6에서와 같이 환산할 수 있고, CR 사용자가 할당하고자 하는 주파수 전체 대역에서 CR 사용자에게 할당할 수 있는 전력(

)을 도7에 나타내었다.In a typical interference temperature model, the interference temperature limit (

) Can be allocated up to

) Can be converted as shown in FIG. 6 and can be allocated to the CR user in the entire frequency band to be allocated by the CR user (

) Is shown in FIG. 7.

8 is a flowchart illustrating a method of allocating the bandwidth and the transmission power of FIG. 4.

The flowchart of FIG. 8 will be described with reference to FIG. 3.

After performing the spectrum sensing, the main user receiver 101 transmits the spectrum data SP_SIG1 and the required signal-to-noise ratio to the CR user transmitter at the request of the CR user transmitter 200 (step S100).

When the CR user transmitter 200 analyzes the spectral data SP_SIG1 and the main user signals are separated from the interference and noise signals, the CR user transmitter 200 performs an ideal interference temperature modeling. If not, general interference temperature modeling is performed, and the interference temperature limit value is satisfied to satisfy the minimum quality of service (QoS) required by the main user by using the spectrum data SP_SIG and the required signal-to-noise ratio of the main user receiver 101. (Step S103).

The CR user transmitter 200 calculates the interference temperature using Equation 1 while increasing the bandwidth based on the center frequency of the CR user (step S105).

When the interference temperature is calculated, the communication capacity according to the bandwidth of the CR user is obtained by using Equations 2 and 3 above (step S107).

After obtaining the communication capacity of the CR user receiver 201, it is determined whether the communication capacity required by the CR user receiver 201 is satisfied (step S109), and if the communication capacity requested by the CR user is not satisfied, the process returns to step S105. Repeating, if satisfied, minimizes the difference between the calculated communication capacity and the required communication capacity and sets the bandwidth corresponding to the minimized communication capacity as the bandwidth of the CR user.

Here, using the equations (4) and (5) as the bandwidth of the CR user, it is possible to determine the transmission power of the CR user for each interference temperature model (step S111).

When determining the bandwidth corresponding to the communication capacity in step S111, the hill climbing algorithm may be used as an optimization algorithm for finding a bandwidth that minimizes the difference between the calculated communication capacity and the required communication capacity.

In summary, the capacity according to the bandwidth is obtained by measuring the interference temperature while increasing the bandwidth of the CR user until the communication capacity required by the CR user is satisfied in order to allocate the bandwidth and transmission power satisfying the required communication capacity of the CR user. After that, the difference between the required dose is minimized.

Thereafter, the interference temperature may be obtained by adding the noise power generated in the main user receiver 101 and the noise power of the main user receiver 101 due to the transmission power allocated to the CR user transmitter 200, and the interference temperature is the interference temperature. Check whether the CR user transmitter 200 satisfies the performance required by the main user receiver 101 to be used by the main user receiver 101 even if the CR user transmitter 200 uses the allocated transmission power. (Step S115)

Here, whether the signal-to-noise ratio of the main user receiver 101 is satisfied can be obtained by comparing the signal-to-noise ratio using the received power and the noise power of the main user receiver 101, and the noise power of the main user receiver 101 is compared with the CR user. The transmit power of the transmitter 200 may be obtained using the pathloss M between the CR user transmitter 200 and the main user receiver 101.

In step S115, if the performance required by the main user receiver 101 is satisfied, the optimized bandwidth and transmit power are allocated to the CR user, and if the performance not required by the main user receiver 101 is not satisfied, the main user receiver 101 is provided. In step S125, the average transmission power allocated to the CR user transmitter 200 is lowered (step S125), and it is determined that the performance required by the main user receiver 101 is satisfied (step S127).

If the performance required by the main user receiver 101 is not satisfied in step S127, step S125 is repeatedly performed until satisfied, and if the performance required by the main user receiver 101 is satisfied, the band of the main user receiver 101 is satisfied. In order to satisfy the communication capacity of the CR user, the transmission power is increased in another band of the CR user transmitter 200 by the power lowered in step S129.

After that, it is determined whether the interference temperature limit is satisfied in another band (step S131). When the interference temperature limit is exceeded, the process returns to step S105 to further increase the bandwidth of the CR user, and to repeat the process of allocating the interference temperature measurement and transmitting power. If the interference temperature limit value is not exceeded, the adjusted bandwidth and transmission power are allocated to the CR user transmitter 200. (Step S117) In addition, step S117 is performed even when the required performance of the main user is satisfied in step S115.

Subsequently, it is determined by considering the signal-to-noise ratio of the CR user receiver 201 whether the optimized bandwidth and transmission power allocated to the CR user transmitter 200 satisfy the performance of the CR user receiver 201. S121)

Here, whether the signal-to-noise ratio of the CR user receiver 201 is satisfied can be determined by calculating the signal-to-noise ratio using the received power and the noise power of the CR-user receiver 201 and comparing the calculated signal-to-noise ratio with the required signal-to-noise ratio. The reception power of the CR user receiver 101 may be obtained using the transmission power of the CR user transmitter 200 and the path loss L between the CR user transmitter 200 and the CR user receiver 201, and the CR user receiver. The noise power of the 201 obtains the transmission power of the main user transmitter 100 using the reception power of the main user receiver 101 and the path loss K, and the transmission power of the main user transmitter 100 and the main user transmitter 100. ) And the loss of noise between the CR user receiver 201 and the noise power when there is no signal from the CR user receiver.

As a result of the determination in step S121, if the performance of the CR user receiver 201 is not satisfied, repeating the process of measuring the interference temperature and allocating the transmission power while increasing the bandwidth of the CR user transmitter 200 by performing step S105. If the performance of the CR user receiver 201 is satisfied, the bandwidth and transmission power information allocated to the CR user transmitter 200 are transmitted to the CR user receiver 201 using a set protocol, and spectrum shaping is performed. Communicates with the CR user receiver 201 using the optimized bandwidth and transmit power allocated to the CR user transmitter 200 by using.

Here, orthogonal frequency division multiplexing (OFDM) or direct sequence spread spectrum (DSSS) may be used for spectral shaping.

Therefore, the bandwidth and transmission power allocated to the CR user transmitter 200 can coexist with the frequency band of the main user and be used.

As described above, the present invention enables coexistence by enabling each communication while ensuring minimum performance for the main user and the CR user.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated.

1 is a view schematically showing the structure of a conventional wireless cognitive communication system.

FIG. 2 is a flowchart illustrating an operation process of a CR user of a sub system in a wireless cognitive communication system of FIG. 1.

3 shows a schematic structure of a communication system according to the present invention.

4 is a diagram illustrating a configuration of the main user device of FIG. 3.

FIG. 5 is a diagram illustrating a configuration of a CR user device of FIG. 3.

FIG. 6 is a graph illustrating a method of allocating transmission power of a CR user in the ideal interference temperature model of FIG. 5.

FIG. 7 is a graph illustrating a method of allocating transmission power of a CR user in the general interference temperature model of FIG. 5.

8 is a flowchart illustrating a method of allocating the bandwidth and the transmission power of FIG. 4.

Claims (13)

A main user device for transmitting and receiving data with a licensed bandwidth and for outputting spectrum data; And Using the licensed bandwidth and the unauthorized bandwidth, and using the spectrum data to determine the interference temperature limit that does not interfere with the communication of the main user device, while increasing the bandwidth from the center frequency to be used 1] calculates the interference temperature, calculates the communication capacity using the allocated temperature minus the interference temperature from the interference temperature limit, and if the calculated communication capacity satisfies the set communication capacity, the bandwidth is converted into CR bandwidth And a CR user device that designates and obtains CR power using the assigned temperature and the CR bandwidth, and transmits and receives data using the CR bandwidth and the CR power within a range not exceeding the interference temperature limit. Wireless communication system. [Equation 1]

f _C : Center frequency B: bandwidth P _I : average interference power k: Boltzmann constant S (f): power spectral density The device of claim 1, wherein the main user device is A main user transmitter for transmitting data using the licensed bandwidth; And A main user receiver for receiving data of the main user transmitter, And receiving data of the CR user device using a set protocol, and outputting data in response to the received data. The method of claim 2, wherein the primary user receiver A receiver configured to receive data of the main user transmitter and data of the CR user device; A spectrum sensing unit searching for a receivable bandwidth and spectrum sensing to output the spectrum data; A data processor for signal-processing data of the main user transmitter and outputting the spectral data and a required first signal-to-noise ratio in response to data of the CR user device; And And a transmitter configured to output the spectrum data and the first signal-to-noise ratio as an RF signal. The method of claim 3, wherein the CR user device is A CR user transmitter for transmitting and receiving data of the main user device using the protocol, and allocating the CR bandwidth and the CR power using the data and the required second signal-to-noise ratio and the center frequency; And And a CR user receiver in communication with the CR user transmitter using the CR bandwidth and the CR power. The method of claim 4, wherein the CR user transmitter is A receiver configured to receive the spectral data and a first signal to noise ratio; Interference temperature modeling is performed using the spectral data, the interference temperature limit value is set, and the interference temperature is calculated using the center frequency, the bandwidth and spectral data while increasing the bandwidth from the center frequency to be used. And calculating the allocation temperature by subtracting the interference temperature from the interference temperature limit, and calculating the communication capacity using the assigned temperature, the bandwidth, the spectrum data, and the path loss, wherein the communication capacity is determined by the CR user device. If the communication capacity is satisfied, the CR bandwidth for minimizing the difference between the calculated communication capacity and the set communication capacity is set, the CR power is calculated using the CR bandwidth, the assigned temperature, and the path loss, and the CR The power of the main user receiver and the CR user receiver To make sure that it meets a data processor to assign said bandwidth and power to the CR; And And a transmitter configured to output data as an RF signal using the CR bandwidth and the CR power. Determine the interference temperature limit that does not interfere with the communication of the main user receiver according to the spectrum data, calculate the interference temperature according to [Equation 2] while increasing the bandwidth from the center frequency to be used in the CR user transmitter, the interference temperature A communication capacity calculating step of calculating an allocated temperature using a limit value and an interference temperature and calculating a communication capacity using the assigned temperature; If the calculated communication capacity satisfies the set communication capacity, the bandwidth that satisfies the communication capacity is designated as the CR bandwidth, the CR power is calculated using the assigned temperature and the CR bandwidth, and the CR bandwidth and the CR power. CR power calculation and performance checking step to check the performance of the main user receiver due to; And Acknowledging and communicating with the CR bandwidth and the CR power to determine whether the performance of the CR user receiver is satisfied, and if the CR bandwidth and the CR power are allocated, the CR bandwidth of the wireless communication system. And CR power allocation method. [Equation 2]

f _C : Center frequency B: bandwidth P _I : average interference power k: Boltzmann constant S (f): power spectral density The method of claim 6, wherein the step of calculating the communication capacity A spectral sensing step of outputting the spectral data generated by spectral sensing of the searchable bandwidth in the main user receiver; A spectral information transfer step of transmitting the spectral data and a first signal-to-noise ratio required by the main user receiver to the CR user transmitter; And And a setting and calculating step of modeling interference temperature using the spectrum data, setting the interference temperature limit value, and calculating the interference temperature and the communication capacity of the CR user transmitter. Bandwidth and CR Power Allocation Method 8. The method of claim 7, wherein the setting and calculating step An interference temperature modeling step of modeling interference temperature using the spectral data and setting an interference temperature limit value using the spectral data and the first signal-to-noise ratio; Increasing the bandwidth from the center frequency while integrating the power spectral density of the spectrum data divided by the bandwidth to obtain the average interference power, the interference temperature calculation using the average interference power, the center frequency, the bandwidth to calculate the interference temperature step; And The communication capacity using the allocation temperature and bandwidth minus the interference temperature, the noise power of the spectrum data, and the path loss between the main user receiver and the CR user transmitter, the CR user transmitter, and the CR user receiver. CR bandwidth and CR power allocation method of a wireless communication system, characterized in that it comprises the step of calculating the CR communication capacity. The method of claim 8, wherein the interference temperature modeling When the signals of the main user receiver are separated from the interference and noise signals by analyzing the spectral data, an ideal interference temperature modeling is performed according to Equation 3 below. When the signals of the main user receiver are not distinguished from the interference and noise signals, a general interference temperature modeling is performed according to Equation 4 below. [Equation 3]

C ^* _id : CR communication capacity in ideal interference temperature modeling f _C : Center frequency B: bandwidth P _I : average interference power P _L : Received power at CR user receiver P ^* : Average maximum transmit power allowed for CR user transmitter T _I : Interference temperature T _L : Interference temperature limit [Equation 4]

C ^* _gen : CR communication capacity in general interference temperature modeling f _C : Center frequency B: bandwidth P _I : average interference power P _L : Received power at CR user receiver P ^* : Average maximum transmit power allowed for CR user transmitter T _I : Interference temperature T _L : Interference temperature limit The method of claim 8, wherein the CR power calculation and performance check step A communication capacity comparison step of comparing the communication capacity with a required communication capacity required by the CR user receiver, and performing again from the interference temperature calculating step if the communication capacity is smaller than the required communication capacity; In the communication capacity comparison step, if the communication capacity is greater than or equal to the required communication capacity, a bandwidth is set to minimize the difference between the calculated communication capacity and the required communication capacity by using an optimization algorithm, and the allocation temperature and the bandwidth and A bandwidth and CR power setting step of calculating the CR power using the path loss; And A CR power adjustment step of determining whether the bandwidth and the CR power satisfy the performance required for the main user receiver, and lowering the CR power if the performance is not satisfied. Power allocation method. The method of claim 10, wherein the CR power adjustment step Calculating a signal-to-noise ratio of the main user receiver using the spectral data, the CR power, and the path loss, and comparing the calculated signal-to-noise ratio with the first signal-to-noise ratio; A bandwidth and CR power allocation step of allocating the bandwidth and the CR power to the CR user transmitter when the performance checking step is satisfied; And If the performance check step is not satisfied, the CR power is lowered and the CR power is increased in another band of the CR user transmitter by the lowered CR power, and the interference temperature due to the raised CR power does not exceed the interference temperature limit. And a band-specific adjustment step for comparing the CR bandwidth and the CR power allocation method of the wireless communication system. The method of claim 11, wherein the adjusting for each band is performed. If the performance verification step is not satisfied, the CR power is lowered, the signal-to-noise ratio of the main user receiver is calculated using the spectral data, the lowered CR power, and the path loss, and the calculated signal-to-noise ratio is the first signal. A performance determining step of lowering the CR power until it satisfies if the signal-to-noise ratio is satisfied; A transmission power compensation step of raising CR power in another band of the CR user transmitter by the lowered CR power; And Calculate the interference temperature in the other band of the raised CR power, check whether the interference temperature limit is exceeded, and if the interference temperature limit is exceeded, start again from the interference temperature calculation step, if not exceed the bandwidth and CR CR bandwidth and CR power allocation method of a wireless communication system, characterized in that it comprises a further band identification step for executing a power allocation step. The method of claim 12, wherein the acknowledgment and communication step The transmission power of the main user transmitter is obtained from the reception power of the main user receiver, and the transmission noise power of the CR user receiver is calculated using the transmission power of the main user transmitter and the path loss between the main user transmitter and the CR user receiver. The total noise power is calculated by adding the transmission noise power of the CR user receiver and the noise power when there is no signal of the CR user receiver, and calculating the signal-to-noise ratio of the CR user receiver using the total noise power and the CR power. A CR user performance checking step of checking whether the CR user receiver is satisfied with the second signal-to-noise ratio required by the CR user receiver; And And if the CR user performance checking step is not satisfied, starting from the interference temperature calculating step, and if the CR user performance checking step is satisfied, communicating and determining using the bandwidth and the CR power. CR bandwidth and CR power allocation method of a wireless communication system.

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