KR100970447B1 - Method for reporting average signal-to-noise ratio, and method for resource allocation and cooperation based on the average signal-to-noise ratio - Google Patents

Abstract

The present invention relates to a method for reporting an average signal-to-noise ratio and a method for allocating a base station resource based on the average signal-to-noise ratio and a base station cooperative method, and a method for reporting an average signal-to-noise ratio that does not change rapidly over time and space in a mobile Internet terminal. A base station resource allocation and base station cooperation method for increasing system capacity through efficient resource usage and interference control by base station resource allocation and base station cooperation based on the average signal-to-noise ratio is provided.

To this end, the present invention provides a base station resource allocation and base station cooperation method, comprising: determining a base station resource allocation and a base station cooperation method using average signal-to-noise ratio information received from a terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station resource allocation and base station cooperative scheme; And checking whether there is a reporting of the average signal-to-noise ratio from the terminal and proceeding to the transmission step if there is no report of a new average signal-to-noise ratio, and proceeding to the determination step if there is a report of a new average signal-to-noise ratio. It includes a step.

Base station resource allocation, base station cooperation, average signal-to-noise ratio (SNR), average capacity calculation, system capacity increase

Description

Method for reporting average signal-to-noise ratio, and method for resource allocation and cooperation based on the average signal-to-noise ratio}

The present invention relates to a method for reporting average signal-to-noise ratio in a portable internet terminal and the like, and to a method for allocating base station resources and a base station cooperation in a portable internet system. More particularly, the present invention does not change rapidly with time and space in a portable internet terminal. A method of reporting an average signal-to-noise ratio, and performing base station resource allocation and cooperation between base stations based on the average signal-to-noise ratio (SNR) in a mobile Internet system including an indoor / outdoor base station. A base station resource allocation and base station cooperation method for increasing system capacity.

Here, base station resource allocation means base station frequency allocation through cell planning, and cooperation between base stations means that neighboring base stations simultaneously transmit signals to the same user terminal.

In addition, the base station in the present invention includes an outdoor base station installed outdoors, an indoor base station separately installed indoors, and an indoor base station group installed in a group. In addition, indoor base stations installed separately include indoor indoor base stations used in homes, and indoor base stations installed in groups include a group of indoor indoor base stations that can be used in an enterprise.

In the following embodiment according to the present invention will be described by taking a portable Internet system and a portable Internet terminal consisting of an indoor / outdoor base station as an example, but the present invention is not limited thereto.

A conventional base station resource allocation scheme may be a formal cell-based static resource allocation scheme. That is, when the spacing of the base stations to be arranged is constant, a single cell reuse or a multi-cell reuse technique of frequency may be used in consideration of the spacing of the base stations. Such a technique can be applied when the location of the base station is formalized, and thus it is difficult to apply it when the indoor user arbitrarily installs the base station. In addition, since the base station resource allocation method does not consider the distribution of users, the efficiency is inferior in terms of capacity.

Looking at the prior art in more detail, in general, the existing cell (cell) including the outdoor base station has pursued simplicity in terms of system operation through static resource allocation and base station non-cooperation. However, indoor base stations, including outdoor base stations, are difficult to apply cell planning techniques applied in existing outdoor base stations. In case of a home base station, it is possible to install a base station arbitrarily if necessary in the home, and in the case of an enterprise base station, the resource shortage problem and the signal interference problem between the base stations due to the sufficient distance between the base stations is a serious problem.

Therefore, there is a problem that the system capacity is reduced in the case of pursuing simplicity through the existing static resource allocation and non-cooperation of the base station, it is a problem of the present invention to solve this problem.

Accordingly, an object of the present invention is to provide a method for reporting an average signal-to-noise ratio that does not change rapidly with time and space in a portable Internet terminal.

It is another object of the present invention to provide a base station resource allocation and base station cooperative method for increasing system capacity through efficient resource use and interference control based on base station resource allocation and base station cooperation based on average signal-to-noise ratio.

In other words, the present invention reduces the complexity of system operation by using base station resource allocation and base station cooperation through average signal-to-noise ratio (SNR), which does not change rapidly over time and space. Another object is to provide a base station resource allocation and base station cooperation method that can reduce information.

That is, the present invention can increase the system capacity by minimizing the increase of the complexity of the terminal and the increase of the complexity of the control router (ACR) by using the same resources in preparation for the existing static resource allocation and non-cooperation method of the base station. Another object is to provide a base station resource allocation and base station cooperation method.

In addition, the present invention increases system capacity through efficient resource usage and interference control using the same dynamic base station resource allocation and base station cooperative schemes, even when the existing base stations are configured in the same pattern as well as in atypical patterns. It is another object to provide a base station resource allocation and base station cooperation method that can be.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to a first aspect of the present invention, there is provided a method for reporting an average signal-to-noise ratio, comprising: determining an active BS having a signal-to-noise ratio greater than or equal to a threshold; Selecting, from the determined active base stations, an active base station group belonging to a control unit that manages a primary BS; Feeding back an average signal-to-noise ratio of the selected active base station group to the controller side; And checking whether the average signal-to-noise ratio has changed, and if the average signal-to-noise ratio is changed, repeating the selection from the selecting step.

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On the other hand, the second method of the present invention for achieving the other object, in the base station resource allocation and base station cooperation method, using the average signal-to-noise ratio information received from the terminal side to determine the base station resource allocation and base station cooperation scheme Determining step; A transmission step of each base station transmitting a signal to the terminal according to the determined base station resource allocation and base station cooperative scheme; And checking whether there is a reporting of the average signal-to-noise ratio from the terminal and proceeding to the transmission step if there is no report of a new average signal-to-noise ratio, and proceeding to the determination step if there is a report of a new average signal-to-noise ratio. It includes a step.

On the other hand, the third method of the present invention is a base station resource allocation method, comprising: determining a base station resource allocation scheme using average signal-to-noise ratio information received from a terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station resource allocation scheme; And checking whether there is a reporting of the average signal-to-noise ratio from the terminal and proceeding to the transmission step if there is no report of a new average signal-to-noise ratio, and proceeding to the determination step if there is a report of a new average signal-to-noise ratio. It includes a step.

On the other hand, the fourth method of the present invention, the base station cooperation method, Determining the base station cooperation method using the average signal-to-noise ratio information received from the terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station cooperative scheme; And checking whether there is a reporting of the average signal-to-noise ratio from the terminal and proceeding to the transmission step if there is no report of a new average signal-to-noise ratio, and proceeding to the determination step if there is a report of a new average signal-to-noise ratio. It includes a step.

On the other hand, the fifth method of the present invention provides a method for allocating a base station resource, comprising: selecting a base station for increasing an average capacity by using average signal-to-noise ratio information received from a terminal and allocating different frequencies; Selecting a base station whose capacity is increased than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a base station that has not been assigned at least one frequency.

On the other hand, the sixth method of the present invention, the base station resource allocation method, comprising: selecting a terminal to increase the average capacity by using the average signal-to-noise ratio information received from the terminal and assigning different frequencies; Selecting a terminal having an increased capacity than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a terminal that has not been assigned at least one frequency.

On the other hand, the seventh method of the present invention, the base station cooperation method, the base station selection step of selecting the base station of the minimum capacity for each frequency as the initial base station; Selecting a base station whose maximum capacity is increased through cooperation of the initial base station and a base station using average signal-to-noise ratio information as a pair base station; And repeating the initial base station selection step as there is an increase in capacity when the base station does not cooperate.

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As described above, the present invention efficiently solves the problem of inefficient resource usage due to the existing problem of static base station resource allocation and interference between base stations through base station non-cooperation, through dynamic base station resource allocation using average signal-to-noise ratio and base station cooperative method. By controlling, the transmission capacity of the portable Internet system can be increased.

As described above, the present invention has an effect of increasing system capacity through efficient resource usage and interference control by base station resource allocation and base station cooperation based on average signal-to-noise ratio.

In other words, the present invention reduces the complexity of system operation by using base station resource allocation and base station cooperation through average signal-to-noise ratio (SNR), which does not change rapidly over time and space. The effect is to reduce the information.

That is, the present invention minimizes the complexity of the terminal through dynamic base station resource allocation and base station cooperation based on the location of the user terminal serviced in the base station, that is, the average signal-to-noise ratio, compared to the existing static resource allocation and base station non-cooperative scheme. In addition, the complexity of the control router (ACR) can be minimized to increase the system capacity.

In addition, the present invention provides system capacity through efficient resource usage and interference control using the same dynamic base station resource allocation and base station cooperative schemes, even when the existing base station is configured in the same pattern as well as the atypical pattern. There is an effect that can be increased.

In addition, the present invention has the effect of increasing the minimum capacity of the edge user terminal through cooperation between the base station at the edge of the base station.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the technical gist of the present invention will be described in order to help understand an average signal-to-noise ratio reporting method, a dynamic base station resource allocation and a base station cooperation method based on the average signal-to-noise ratio according to the present invention.

Information needed for dynamic base station resource allocation and base station cooperation is average signal-to-noise ratio information between the base station and the user terminal (portable Internet terminal). Here, the average signal-to-noise ratio (SNR) is a variable that does not change rapidly with the movement of the user terminal and the change of the surrounding environment. Accordingly, the amount of information and the number of times that each user terminal of the base station needs to feed back are remarkably small compared to the existing technology of allocating resources by feeding back a channel at once. In addition, in the home / business portable Internet situation in which the user terminal is hardly moved, the average signal-to-noise ratio of the user terminal does not change for a long time. Therefore, the dynamic base station resource allocation and the base station cooperation method using the same have significantly lower feedback information amount and base station complexity than the conventional technology.

And for dynamic resource allocation and cooperation using a base station managed by the same control router (ACR) using the average signal-to-noise ratio of the user terminal, the user terminal information about the primary base station having the highest signal-to-noise ratio Unlike the conventional method of feeding back the feedback, the control unit (ACR) to which the current primary (primary) base station (ACR) is managed to feed back the average signal-to-noise ratio of the active (base). The active base station is a base station whose received signal-to-noise ratio is greater than or equal to a threshold.

After the base station receives the feedback of the average signal-to-noise ratio of the user terminal through the above-described method, the control router (ACR) controlling several base stations performs resource allocation of the base station and cooperation between the base stations in terms of maximizing the average capacity. . At this time, the base station resource allocation and the base station cooperation scheme will follow the predetermined scheme without changing unless the average signal-to-noise ratio of the user terminal currently receiving the service is changed. Therefore, the update point of the algorithm (ie, the base station resource allocation and the base station cooperative scheme change point) may be changed when the average signal-to-noise ratio of the user terminal changes or when the user terminal currently being serviced by the base station does not receive the service. It happens when you want to get a new service.

Next, a method for reporting an average signal-to-noise ratio and a base station resource allocation and base station cooperation method based on the average signal-to-noise ratio will be described in detail with reference to FIGS. 1A and 1B.

FIG. 1A is a flowchart illustrating an average signal-to-noise ratio reporting method according to the present invention, and illustrates an operation in a user terminal (portable Internet terminal).

First, the user terminal determines an active BS whose signal-to-noise ratio (SNR) is greater than or equal to a threshold (101).

Subsequently, the user terminal includes an active BS group belonging to a control router (ACR) that manages a primary BS having the highest signal-to-noise ratio (SNR) among the determined active BSs. set).

Thereafter, the user terminal feeds back the average signal-to-noise ratio (SNR) of the selected active BS group to the control router (ACR) side through the base station (103).

Then, the user terminal checks whether the average signal-to-noise ratio (SNR) has changed (104), and if there is a change in the average signal-to-noise ratio (SNR), the primary BS having the highest signal-to-noise ratio (SNR) is present. The process is repeated from step 102 of selecting an active BS group belonging to the control router ACR. If there is no change in the average signal-to-noise ratio (SNR), it returns.

In this case, the average signal-to-noise ratio reporting method illustrated in FIG. 1A may be implemented to be repeatedly performed at a predetermined time (for example, 30 seconds or 1 minute) using a timer.

FIG. 1B is a flowchart illustrating an operation of a base station resource allocation and base station cooperation method based on an average signal-to-noise ratio according to the present invention, and illustrates an operation in a control router (ACR).

First, the control router (ACR) determines the base station resource allocation and the base station coordination scheme by using the average signal-to-noise ratio (SNR) information received from the user terminal (mobile Internet terminal). A process 111 of determining a base station resource allocation and a base station cooperation method using the average signal-to-noise ratio (SNR) information will be described later in detail with reference to FIGS. 5A and 5B.

Then, each base station transmits a signal to the user terminal according to the determined base station resource allocation and base station cooperative scheme (112).

After the signal transmission, check whether there is a reporting of the average signal-to-noise ratio (SNR) from the user terminal (113), and if there is no report of a new average signal-to-noise ratio (SNR), the predetermined base station resource allocation and base station Repeat the process of transmitting the signal to the user terminal according to the cooperative method 112, and if there is a report of a new average signal-to-noise ratio (SNR) proceeds to step "111" to newly determine the base station resource allocation and base station cooperative method After that, repeat the following process.

As described above, the base station resource allocation and the base station cooperation according to the present invention may be implemented together, the base station resource allocation method according to the present invention may be implemented, or the base station cooperation method according to the present invention may be implemented. .

2 is a diagram illustrating an example in which two neighbor base stations transmit data to a user terminal using different frequencies, and FIG. 3 is a diagram when two neighbor base stations transmit data to a user terminal using the same frequency. It is a figure which shows an example.

Base station 1 of FIG. 2 transmits data to user terminal 1 using frequency 1, and base station 2 of FIG. 2 transmits data to user terminal 2 using frequency 2 different from that of base station 1. FIG. As described above, the two neighboring base stations use different frequencies from each other, and there is no interference problem from the adjacent base stations. However, there are disadvantages in that frequency resources are wasted due to the use of two different frequencies.

The base station 1 of FIG. 3 transmits data to the user terminal 1 and the user terminal 2 using both the frequency 1 and the frequency 2, and the base station 2 of FIG. 3 also uses the frequency 1 and the frequency 2 of the user terminal 1 and the user terminal 2. Is sending data to. As described above, a method in which two neighboring base stations use the same frequency has a disadvantage in that signals from neighboring base stations act as interference. However, there is an advantage that the frequency can be used efficiently compared to the method of FIG.

Therefore, when the interference from the neighboring base station is large, the scheme of FIG. 2, that is, the neighboring base station uses different frequencies from each other, is superior in capacity, and when the interference from the neighboring base station is small, the scheme of FIG. The use of this same frequency prevails in terms of capacity.

4 is a diagram illustrating an example of transmitting data through cooperation between neighboring base stations according to the present invention.

Here, the base station cooperation refers to a technique in which neighboring base stations select the same frequency and transmit a signal to the same user terminal. In the present invention, a signal transmission through an existing space-time block coding scheme is considered through cooperation between base stations.

As shown in FIG. 4, user terminal 1 receives data from two base stations 1 and 2 using frequency 1, and user terminal 2 uses a frequency different from frequency 1 used by user terminal 1, that is, frequency 2. Receive signals from two base stations 1 and 2. Such a method may be referred to as a technique of controlling interference by different neighboring base stations simultaneously transmitting data to the same user terminal using the same frequency when the interference between the base stations is large.

In the three data transmission methods described with reference to FIGS. 2 to 4, there is a technology having excellent performance by the relative positions of the user terminal and the base station. Accordingly, the present invention proposes an algorithm for dynamic base station resource allocation and base station cooperation in terms of maximizing the total system capacity.

Meanwhile, in the aforementioned flowchart of FIG. 1B (base station resource allocation and base station cooperation method based on average signal-to-noise ratio according to the present invention), the base station resource allocation and base station cooperation method may be determined based on the average signal-to-noise ratio. In this case, a measure of average capacity considering interference of neighboring base stations is required.

Therefore, a new measurement method for measuring the average capacity is as follows. When there are K base stations using the same frequency and the k-th user terminal receives a signal through the k-th base station, the average capacity considering the interference from the K-1 base stations using the same frequency is given by the following equation. 1].

는 i번째 기지국에서 k번째 사용자 단말기까지의 평균 파워를 나타내고

는 i번째 기지국에서 k번째 사용자 단말기까지의 채널을 나타낸다. 그리고

은 사용자 단말기의 노이즈 파워를 나타낸다.In [Equation 1]

Denotes the average power from the i base station to the k th user terminal

Denotes a channel from the i th base station to the k th user terminal. And

Represents the noise power of the user terminal.

As can be seen from [Equation 1], all signals at the same frequency other than the signal from the k-th base station act as interference to the k-th user terminal. Under the assumption that the channel between the base station and the user terminal is a Rayleigh fading environment, Equation 1 is expressed by Equation 2 below.

는 i번째 기지국에서 k번째 기지국까지의 평균 신호 대 잡음비를 나타내고

와 같이 표현되며,

은 지수 적분(exponential integral) 함수를 나타내고

로 표현된다. 상기 [수학식 2]의 유도 과정은 하기의 [수학식 3]과 같다.In Equation 2 above

Denotes the average signal to noise ratio from the i base station to the k base station

Expressed as

Represents an exponential integral function

It is expressed as The derivation process of Equation 2 is as shown in Equation 3 below.

는

을 치환한 값이고

의 분포는

가 평균이 0이고 분산이 1인 복소수 가우시안 분포를 가진다고 가정할 경우 평균이

을 가지는 지수 분포

를 따르므로 상기 유도 과정의 세 번째 등식이 성립한다. 세 번째 등식의 적분을 상기 유도한 지수 분포의 범위인 0에서 무한대까지 수행하면 네 번째 등식이 유도된다. 네 번째 등식에서

을

로 치환하면 다섯 번째 등식이 성립한다. 상기

는 i번째 기지국과 k번째 사용자 단말기 사이의 평균 신호 대 잡음비를 나타낸다.In the derivation process of Equation 3

Is

Is the value of

The distribution of

Assuming that has a complex Gaussian distribution with mean 0 and variance 1,

Distribution with

Since the third equation of the derivation process holds. Performing the integration of the third equation from 0 to infinity, the range of the derived exponential distribution, leads to the fourth equation. In the fourth equation

of

Substituting for holds the fifth equation. remind

Denotes an average signal-to-noise ratio between the i-th base station and the k-th user terminal.

Therefore, the closed equation of [Equation 2] is derived, and [Equation 2] represents the average capacity of the k-th user terminal when there is interference from K-1 base stations when there is no cooperation between base stations, and the average The capacity is expressed as a function of the average signal-to-noise ratio (SNR) between the base station transmitting the signal to the k-th user terminal and the base station serving as the interference and the user terminal.

On the other hand, in the case of transmitting a signal through cooperation between the base station, the average capacity of the k-th user terminal is expressed as shown in Equation 4 below.

는 k번째 기지국을 제외한

개의 기지국이 동시에 협력할 경우 협력하는 기지국의 인덱스를 나타낸다.

는

그룹(set) 내에 포함되는 기지국 수를 나타낸다.

는 k번째 기지국을 제외한

개의 기지국이 동시 협력을 하지 않을 경우 동시 협력을 하지 않는 기지국의 인덱스를 나타낸다. 상기에서

의 관계가 성립한다. 기지국과 사용자 단말기 간의 채널이 레일레이 페이딩(Rayleigh fading) 환경이라는 가정 하에 상기 [수학식 2]의 닫힘꼴 수식을 상기 [수학식 3]과 같이 유도한 것과 같은 방식으로 상기 [수학식 4]를 닫힘꼴 수식으로 나타내면 하기의 [수학식 5]와 같이 표현된다.In [Equation 4] above

Excluding kth base station

When two base stations cooperate at the same time, this indicates the index of the cooperating base station.

Is

The number of base stations included in a group is shown.

Excluding kth base station

If two base stations do not co-exist, this indicates the index of the base station that does not co-exist. From above

The relationship is established. Assuming that the channel between the base station and the user terminal is a Rayleigh fading environment, [Equation 4] is derived in the same manner as inducing the closed equation of [Equation 2] as shown in [Equation 3]. When expressed as a closed formula, it is expressed as Equation 5 below.

는 i번째 기지국에서 k번째 기지국까지의 평균 신호 대 잡음비를 나타내고

와 같이 표현된다. 상기 [수학식 5]는

개의 기지국 간의 협력이 있을 경우의 k번째 사용자 단말기의 평균 용량을 나타내고, 상기 평균 용량은 k번째 사용자 단말기에게 신호를 전송하는

개의 기지국 및 간섭으로 작용하는 기지국과 사용자 단말기 간의 평균 신호 대 잡음비(SNR)의 함수로 표현된다.In Equation 5 above

Denotes the average signal to noise ratio from the i base station to the k base station

It is expressed as [Equation 5] is

Represents the average capacity of the k-th user terminal when there is cooperation between two base stations, and the average capacity transmits a signal to the k-th user terminal.

It is expressed as a function of the average signal-to-noise ratio (SNR) between the two base stations and the base station serving as the interference and the user terminal.

Looking at the process 111 of determining the base station resource allocation and the base station cooperation scheme in the scenario of Figure 1b using the derived closed equations [Equation 2] and [Equation 5] as follows.

In general, the optimal method for determining the base station resource allocation and the base station cooperation scheme has a problem that the complexity increases exponentially as the number of base stations controlled by the control router (ACR) and the number of assignable frequencies increase. .

Accordingly, the present invention proposes a method of using sub-optimal methods instead of the optimal method for base station resource allocation and base station cooperation. Here, when the base station resource allocation and base station cooperation scheme are determined, the optimal scheme means deriving an average sum capacity for all possible combinations to determine the base station resource allocation and base station cooperation scheme. In contrast, the suboptimal scheme does not look at all possible combinations of base station resource allocation and base station cooperation schemes, but instead of looking at all possible combinations of base station resource allocations and base station cooperation schemes, two-stage allocation and cooperation in which sequential base station cooperation is performed after sequential base station resource allocation is performed to reduce complexity. Means the way.

Looking at these two-stage base station resource allocation and base station cooperation method in more detail as follows. Herein, a case where a new base station is added will be described as an example.

First, it is assumed that a control router (ACR) for controlling a plurality of base stations exists for base station resource allocation and base station cooperation, and the number of base stations controlled through the control router (ACR) is K.

The first step is to select N base stations with the largest average channel capacity among the K base stations, and assign different frequencies to each of the selected N base stations. At this time, since N base stations are allocated different frequencies, there is no interference with each other. Accordingly, the N base stations with the largest average channel capacity become the base stations to which the N users having the largest distance from the base station to the user terminal, that is, the largest average signal-to-noise ratio of the user terminal belong. In this case, the average capacity at the k-th base station is expressed as in Equation 6 below.

After selecting the base stations having N independent frequencies, frequencies are allocated to the new base stations through the following sequential algorithms for each of the N frequencies. For each of the N frequencies, a new base station that has not been assigned a frequency is added one by one, and the base station having the largest capacity increase is selected and the corresponding frequency is allocated. In this case, the capacity considering the newly added base station is obtained by using the closed equation of Equation 2 above. If the capacity increase due to reuse of the same frequency is greater than the capacity reduction of the entire system due to the increase in interference caused by the addition of a new base station using the same frequency, there is an increase in the capacity of the entire system. Therefore, the base station using the same frequency is selected until the capacity increase no longer occurs.

When the capacity increase no longer occurs, if all base stations have not been allocated a frequency, a frequency with the least capacity reduction is allocated to the base station to which the frequency is not allocated for fair resource allocation. If all base stations have been assigned at least one frequency, the base station resource allocation algorithm, which is the first step, is terminated.

As a second step, the cooperative algorithm between base stations is as follows. Base station coordination is a technology that uses interference of other base stations when the capacity of the user terminal at the edge of the base station decreases due to interference. Therefore, the goal is to increase the capacity when the capacity is small, ie when the user terminal is at the edge of the base station. Therefore, the base station having the smallest capacity for each frequency is selected as an initial base station for base station cooperation, and a base station whose capacity is most increased through base station cooperation with the selected initial base station is selected as a pair base station. At this time, the capacity of the newly cooperating base station is obtained using the closed equation of Equation 5 above.

If there is an increase in capacity compared to when the base station does not cooperate after selecting a pair base station for coordination as described above, the base station having the smallest capacity among other base stations except for the previously selected base station is selected as the initial base station again. Search for a pair base station for cooperation. If there is no capacity increase, if the base station cooperation is not performed, the base station cooperation algorithm is terminated.

Each base station transmits a signal to a user terminal in a base station resource allocation and base station cooperative manner determined by the two base station resource allocation and base station cooperative algorithms.

5A is a detailed flowchart of an embodiment of a base station resource allocation and base station cooperation method according to the present invention when a new base station is added.

First, using the average SNR information fed back from the user terminal is selected N base stations of the largest increase in the average channel capacity of the K base stations (501).

Thereafter, different frequencies are allocated to the selected N base stations (502).

Then, when a new base station is added using the average SNR information for frequency 1, the base station having the largest capacity increase is selected and the corresponding frequency 1 is allocated (503).

Then, if the base station is not added, check whether there is an increase in capacity (504). If the base station is not added, if there is an increase in capacity, the process proceeds to "503" and adds another base station to increase the base station with the largest capacity increase. Select and assign the corresponding frequency 1. If the base station is not added, if there is no capacity increase, the process proceeds to the next step (507).

At this time, the same process is performed in parallel for N frequencies for each frequency (505, 506).

If the capacity increase no longer occurs for all frequencies, it is checked (searched) whether all base stations have been assigned at least one frequency (507).

As a result of the check 507, if there is a base station that has not been allocated a frequency, a frequency with the least capacity reduction is allocated to the base station that has not been allocated a frequency by using average SNR information (508). If all base stations have been assigned at least one frequency, the base station resource allocation algorithm is completed.

Then, the base station with the smallest capacity for frequency 1 is selected as an initial base station for base station cooperation (509).

Thereafter, using the average SNR information, the base station with the largest capacity increase is selected as a pair base station through the initial base station and base station cooperation (510).

Thereafter, if there is an increase in capacity when the base station does not cooperate (511), if there is an increase in capacity when the base station does not cooperate, the process proceeds to the "509" process and selects another base station with the smallest capacity. If there is no increase in capacity, the process proceeds to the next step (112).

At this time, the same process is performed in parallel for N frequencies for each frequency (512 to 514).

When the capacity increase no longer occurs for every frequency, each base station transmits a signal to the user terminal according to the determined base station resource allocation and base station cooperation scheme (112).

Next, for example, when a new user terminal is added, it is as follows.

5B is a detailed flowchart illustrating an embodiment of a base station resource allocation and base station cooperation method based on an average signal-to-noise ratio when a new user terminal is added.

First, N user terminals that greatly increase the average channel capacity among the K user terminals are selected using the average SNR information fed back from the user terminal (521).

Thereafter, different frequencies are allocated to the selected N user terminals (522).

Subsequently, when a new user terminal is added using the average SNR information with respect to frequency 1, the user terminal with the largest capacity increase is selected and the corresponding frequency 1 is allocated (523).

After that, if the user terminal is not added, check whether there is an increase in capacity (524). If the user terminal is not added, if there is an increase in capacity, the process proceeds to "523" and adds another user terminal to increase the capacity. Select a large user terminal and assign that frequency 1. If the user terminal is not added and there is no capacity increase, the process proceeds to the next step (step 527).

At this time, the same process is performed in parallel for N frequencies for each frequency (525, 526).

If the capacity increase no longer occurs for all frequencies, it is checked (searched) whether all user terminals have been allocated at least one frequency (527).

As a result of the check 527, if there is a user terminal that has not been assigned a frequency, the frequency with the least capacity reduction is allocated to the user terminal that has not been assigned a frequency using average SNR information (528). If all user terminals are assigned at least one frequency, the base station resource allocation algorithm is completed.

Then, for the frequency 1, the user terminal with the smallest capacity is selected (529). At this time, the base station to which the user terminal with the smallest capacity belongs is an initial base station for base station cooperation.

Thereafter, using the average SNR information, a base station that greatly increases the capacity of the selected user terminal through the base station cooperation with the base station is selected as a pair base station (530).

Thereafter, if there is an increase in the capacity when the base station does not cooperate (531), if there is an increase in the capacity when the base station does not cooperate, the process proceeds to "529" to select another user terminal having the smallest capacity. If there is no increase in capacity, the process proceeds to the next step (112).

At this time, the same process is performed in parallel for N frequencies for each frequency (532 to 534).

When the capacity increase no longer occurs for every frequency, each base station transmits a signal to the user terminal according to the determined base station resource allocation and base station cooperation scheme (112).

Next, the performance of the dynamic base station resource allocation and the base station cooperation method according to the present invention as described above are as follows. The following conditions are assumed for the performance verification of the base station resource allocation and the base station cooperation scheme according to the present invention. It is assumed that four base stations can be controlled through one control router (ACR), and each base station serves one user terminal. The total assignable frequencies are assumed to be four, and the comparing system is a one-cell reuse system in which four base stations share the same frequency (see FIG. 6) and a four-cell reuse system in which four base stations use different frequencies (FIG. 7).

The 1-cell frequency reuse system tends to increase capacity due to frequency reuse, but if the interference between each other is large, the capacity tends to decrease due to interference, and the 4-cell frequency reuse system does not interfere with each other but interference due to inefficient use of frequency. If it is small, it is a large capacity loss system.

이고 기지국과 사용자 단말기 간의 거리가 10m 이상일 경우

와 같이 나타낼 수 있다.In addition, it is assumed that the power of the base station is 100 mW (20 dBm), the noise level of the user terminal is -104 dBm, and the distance between the base stations is 10 m to 150 m. The user terminal is uniformly and randomly located in the cell. The frequency is 2.3 GHz, and the pathloss model is "802.11n pathloss model D". "802.11n pathloss model D" is when the distance between the base station and the user terminal is less than 10m

If the distance between the base station and the user terminal is more than 10m

Can be expressed as:

FIG. 8 compares the capacity of the existing 1-cell and 4-cell frequency reuse schemes with the dynamic base station resource allocation and base station coordination schemes as the distance between base stations is gradually increased from 10m to 150m.

In Figure 8, the horizontal axis represents the distance between the base stations, the vertical axis represents the average rate (average rate) is a unit of bits / sec / Hz / cell. As can be seen from the performance results, when the dynamic base station resource allocation and the cooperative base station method of the present invention are used, the performance is similar to the method of reusing 4-cell frequency when the distance between base stations is close, and when the distance between base stations is far from each other, The performance is similar to the reuse method.

In case of distance between base stations, it is beneficial to reduce the interference between base stations by using different frequencies between adjacent base stations. In case of distance between base stations, it is advantageous to reuse the same frequency between base stations. Indicates that there is.

Therefore, the dynamic base station resource allocation and the base station cooperation method according to the present invention can be seen that the best performance by adaptively assigning the frequency according to the relative position of the base station and the user terminal, that is, the cooperation of the base station. If the distance between the base station is 10m, the method of the present invention has a capacity gain of 123% compared to the existing one-cell reuse, and if the distance between the base stations is 150m, the method of the present invention has a capacity gain of 34% compared to the existing four-cell reuse method. Bring it.

9 illustrates an increase in capacity of a base station having a minimum capacity when only base station resource allocation is performed compared to when base station resource allocation and base station cooperation are simultaneously performed according to the present invention.

As described above, since the base station cooperation is a method of increasing the capacity of the user terminal located at the edge of the base station, the capacity of the base station having the minimum capacity is compared. As shown in FIG. 9, when the base station resource allocation and the base station cooperation according to the present invention are performed at the same time, it can be seen that the capacity of the minimum capacity base station increases by up to 8% compared to the case where only the base station resource allocation is performed.

Therefore, even if only the base station resource allocation method according to the present invention is improved. In addition, even if only the base station cooperation method according to the present invention is improved. Of course, there is an improvement in performance even when using the base station resource allocation method according to the present invention and the existing base station cooperation method, and there is also an improvement in performance even when using the existing base station allocation method and the base station cooperation method according to the present invention.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention can be used in portable Internet terminals, portable Internet systems, and the like.

1A is a flow chart of an embodiment of an average signal-to-noise ratio reporting method according to the present invention;

1B is a flow diagram of an embodiment of a base station resource allocation and base station cooperation method based on an average signal-to-noise ratio according to the present invention;

2 is a diagram illustrating an example in which two neighboring base stations transmit data to a user terminal using different frequencies;

3 is a diagram illustrating an example in which two neighboring base stations transmit data to a user terminal using the same frequency;

4 is a diagram illustrating an example of transmitting data through cooperation between neighboring base stations according to the present invention;

5A is a detailed flowchart of an embodiment of a base station resource allocation and base station cooperation method based on an average signal-to-noise ratio when a new base station is added;

5B is a detailed flowchart illustrating an embodiment of a base station resource allocation and base station cooperation method based on an average signal-to-noise ratio when a new user terminal is added;

6 is a diagram for explaining a one-cell reuse system in which four base stations share the same frequency;

7 is a diagram for explaining a 4-cell reuse system in which four base stations use different frequencies;

8 is a view showing a comparison of system capacity between an existing system according to the distance between the base station and the system of the present invention,

9 is a diagram illustrating an increase in capacity of a base station having a minimum capacity when only base station resource allocation is performed compared to when base station resource allocation and base station cooperation are simultaneously performed according to the present invention.

Claims (25)

delete In the average signal to noise ratio reporting method, Determining an active BS whose signal-to-noise ratio is above a threshold; Selecting, from the determined active base stations, an active base station group belonging to a control unit that manages a primary BS; Feeding back an average signal-to-noise ratio of the selected active base station group to the controller side; And Checking whether the average signal-to-noise ratio has changed and repeating the selection step if there is a change in the average signal-to-noise ratio Mean signal to noise ratio reporting method comprising a. In the base station resource allocation and base station cooperation method, Determining a base station resource allocation and a base station cooperative scheme using average signal-to-noise ratio information received from the terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station resource allocation and base station cooperative scheme; And Check whether there is a reporting of the average signal-to-noise ratio from the terminal, and if there is no report of a new average signal-to-noise ratio, proceeds to the transmission step; step Base station resource allocation and base station cooperation method comprising a. The method of claim 3, wherein The determining step, Selecting a base station increasing an average capacity by using average signal-to-noise ratio information received from the terminal and allocating different frequencies; Selecting a base station whose capacity is increased than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; Allocating a frequency having a minimum capacity reduction to the base station that has not been assigned at least one frequency by using average signal-to-noise ratio information; An initial base station selection step of selecting a minimum capacity base station as an initial base station for each frequency; Selecting a base station whose maximum capacity is increased through cooperation of the initial base station and a base station using average signal-to-noise ratio information as a pair base station; And Repeating from the initial base station selection step as there is an increase in capacity in case of no base station cooperation Base station resource allocation and base station cooperation method comprising a. The method of claim 3, wherein The determining step, Selecting a terminal for increasing an average capacity by using average signal-to-noise ratio information received from the terminal and assigning different frequencies to each other; Selecting a terminal having an increased capacity than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; Allocating a frequency having a minimum capacity reduction to the terminal that has not been assigned at least one frequency by using average signal-to-noise ratio information; An initial base station selection step of selecting, as an initial base station, a base station to which a terminal of minimum capacity belongs to each frequency; Selecting a base station whose maximum capacity is increased through cooperation of the initial base station and a base station using average signal-to-noise ratio information as a pair base station; And Repeating from the initial base station selection step as there is an increase in capacity in case of no base station cooperation Base station resource allocation and base station cooperation method comprising a. The method according to any one of claims 3 to 5, The determining step, Equation A

(K is the number of base stations,

Denotes the average signal to noise ratio from the i base station to the k base station

Expressed as

Represents the exponential integration function

Expressed as The base station resource allocation and base station cooperation method, characterized in that the average capacity is calculated as shown in [Equation A] when there is interference from the neighboring base station during base station resource allocation. The method according to any one of claims 3 to 5, The determining step, Equation B

(K is the number of base stations,

Denotes an index of base stations that do not co-operate,

Denotes the average signal to noise ratio from the i base station to the k base station

Expressed as The base station resource allocation and base station cooperation method, characterized in that the average capacity is calculated as shown in [Equation B] when there is interference from the adjacent base station when the base station cooperates. In the base station resource allocation method, Determining a base station resource allocation method using average signal-to-noise ratio information received from the terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station resource allocation scheme; And Check whether there is a reporting of the average signal-to-noise ratio from the terminal, and if there is no report of a new average signal-to-noise ratio, proceeds to the transmission step; step Base station resource allocation method comprising a. The method of claim 8, The determining step, Selecting a base station increasing an average capacity by using average signal-to-noise ratio information received from the terminal and allocating different frequencies; Selecting a base station whose capacity is increased than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And Allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a base station that has not been assigned at least one frequency. Base station resource allocation method comprising a. The method of claim 8, The determining step, Selecting a terminal for increasing an average capacity by using average signal-to-noise ratio information received from the terminal and assigning different frequencies to each other; Selecting a terminal having an increased capacity than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And Allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a terminal that has not been assigned at least one frequency; Base station resource allocation method comprising a. The method according to any one of claims 8 to 10, The determining step, Equation A

(K is the number of base stations,

Denotes the average signal to noise ratio from the i base station to the k base station

Expressed as

Represents the exponential integration function

Expressed as The base station resource allocation method for calculating the average capacity when there is interference from the neighboring base station in the base station resource allocation as shown in [Equation A]. In the base station cooperation method, A determination step of determining a cooperative base station using average signal-to-noise ratio information received from a terminal side; A transmission step of each base station transmitting a signal to the terminal according to the determined base station cooperative scheme; And Check whether there is a reporting of the average signal-to-noise ratio from the terminal, and if there is no report of a new average signal-to-noise ratio, proceeds to the transmission step; step Base station cooperation method comprising a. 13. The method of claim 12, The determining step, An initial base station selection step of selecting a minimum capacity base station as an initial base station for each frequency; Selecting a base station whose maximum capacity is increased through cooperation of the initial base station and a base station using average signal-to-noise ratio information as a pair base station; And Repeating from the initial base station selection step as there is an increase in capacity in case of no base station cooperation Base station cooperation method comprising a. The method according to claim 12 or 13, The determining step, Equation B

(K is the number of base stations,

Denotes an index of base stations that do not co-operate,

Denotes the average signal to noise ratio from the i base station to the k base station

Expressed as The base station cooperation method, characterized in that the average capacity is calculated as shown in [Equation B] when there is interference from the adjacent base station during the base station cooperation. In the base station resource allocation method, Selecting a base station increasing an average capacity by using average signal-to-noise ratio information received from the terminal and allocating different frequencies; Selecting a base station whose capacity is increased than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And Allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a base station that has not been assigned at least one frequency. Base station resource allocation method comprising a. In the base station resource allocation method, Selecting a terminal for increasing an average capacity by using average signal-to-noise ratio information received from the terminal and allocating different frequencies; Selecting a terminal having an increased capacity than before by using average signal-to-noise ratio information for each frequency and allocating a corresponding frequency; And Allocating a frequency having a minimum capacity reduction by using average signal-to-noise ratio information to a terminal that has not been assigned at least one frequency; Base station resource allocation method comprising a. In the base station cooperation method, An initial base station selection step of selecting a minimum capacity base station as an initial base station for each frequency; Selecting a base station whose maximum capacity is increased through cooperation of the initial base station and a base station using average signal-to-noise ratio information as a pair base station; And Repeating from the initial base station selection step as there is an increase in capacity in case of no base station cooperation Base station cooperation method comprising a. delete delete delete delete delete delete delete delete

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