KR102000667B1 - Method for determining transmitting power in the mimo system based on cooperative transmitting - Google Patents

Abstract

A method for determining transmission power in a multi-antenna system based on cooperative transmission is disclosed. The transmission power determination method includes: setting a power limitation condition of a j-th transmission apparatus and transmission quality information of a k-th reception apparatus; And the transmission power to be allocated to the j < th > transmitting apparatus when the j < th > transmitting apparatus transmits data to the k < th >

Description

[0001] METHOD FOR DETERMINING TRANSMITTING POWER IN THE MIMO SYSTEM [0002] BASED ON COOPERATIVE TRANSMITTING [0003]

The present invention relates to a transmission power determination method, and more particularly, to a transmission power determination method that minimizes a transmission power while satisfying a quality-of-service (QoS) of a user.

Multi Input-Multi Ouput (MIMO) systems exhibit a large performance gain by using a plurality of antennas in a transmitting apparatus or a receiving apparatus. In general, the transmission power used by a transmitting apparatus included in a multi-antenna system decreases in proportion to the number of antennas of the transmitting apparatus. The relationship described above is inversely related to an increase in the received signal-to-noise ratio (SNR) of the receiving apparatus when the number of antennas of the transmitting apparatus increases.

Therefore, if the number of antennas of the transmission apparatus is greatly increased, the reduction gain of the transmission power for satisfying the QoS of the reception apparatus can be maximized. Such a system is defined as a " massive multi-antenna system ".

Meanwhile, in order to efficiently use the limited frequency resources, all base station-cell phone related wireless communication standards define that a plurality of cells share the same frequency to communicate. At this time, there is a problem that intercell interference (ICI) exists due to the use of the same frequency by a plurality of cells, and cell interference is limited due to such interference.

Accordingly, a cooperative MIMO system in which adjacent transmitting apparatuses of a plurality of cells cooperate to support a multi-user (MU) has been proposed. Transmission devices are connected by a high-speed optical cable and exchange channel data of the user of each cell and transmission data through the optical cable. Based on the exchanged information, the transmitting apparatuses of a plurality of cells cooperate to transmit data to the receiving apparatus, thereby effectively reducing interference between cells and increasing the capacity of the entire system. The cooperation of the transmitting apparatus also has advantages such as power gain and channel gain. Due to these advantages, the cooperative multi-antenna system is utilized as a main technology for expanding the coverage by increasing the capacity of cell-edge users in IMT-Advanced.

Collaborative communication beamforming design and power allocation to develop transmitters in cooperative multi-antenna systems occurs under the power limitations of the system. At this time, there are two types of usage power limit: a pooled-power constraint that allows free use of the total available power of the transmitting devices participating in the cooperative transmission; The second is the per-base power constraint, which is a condition limiting the maximum power of each of the transmitting devices participating in the cooperative transmission.

However, if the power allocation is made according to the pooled-power constraint, there may be situations where excessive power may be used by some transmitting devices, which may cause severe interference to neighboring cells. Therefore, the per-base power constraint is often used as a power constraint.

A beamforming technique and a power allocation technique for reducing transmission power are applied in a multi-user / multi-user (MIMO) system. However, there is a need for an optimal beamforming technique that minimizes the transmission power of a transmitting apparatus while satisfying the QoS of each receiving apparatus in multiple cells, and a technique of allocating power for each beamforming.

According to an embodiment of the present invention, there is provided a transmission power determination method comprising: setting a power limitation condition of a j-th transmission apparatus and transmission quality information of a k-th reception apparatus; And determining a transmission power to be allocated to the j-th transmitting apparatus when the j-th transmitting apparatus transmits data to the k-th receiving apparatus using the power limiting condition and transmission quality information.

According to another aspect of the present invention, there is provided a transmission power determination method comprising: setting a maximum power available in a j th transmission apparatus; setting target quality information associated with the kth receiving device; And determining a minimum transmission power to be allocated to the jth transmission apparatus in consideration of the maximum power and the target quality information.

According to another aspect of the present invention, there is provided a transmission power determination method comprising: setting a zero-forcing based beamforming vector associated with a kth receiving device; And determining a minimum transmission power to be allocated to a j th transmitting apparatus corresponding to the beamforming vector of the kth receiving apparatus.

According to an embodiment of the present invention, the transmission power of the transmitting apparatus can be minimized while satisfying the QoS of each receiving apparatus and the power limitation condition of the transmitting apparatus.

1 is a diagram illustrating a cooperative based multi-antenna system according to an embodiment of the present invention.
2 is a flowchart showing a transmission power determination method according to an embodiment of the present invention.
3 is a diagram illustrating a transmission power determination method according to another embodiment of the present invention.
4 is a diagram illustrating a transmission power determination method according to another embodiment of the present invention.
FIG. 5 is a diagram illustrating a total transmission power according to the number of antennas of a transmitting apparatus, according to an embodiment of the present invention.
6 is a diagram illustrating a probability based on available transmit power of a transmitting apparatus, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, a method for minimizing transmission power in a cooperative transmission based multi-antenna system for green communication is proposed. In this case, introduction of massive multi-antenna system enables more efficient transmission power reduction. In addition, a zero-forcing based beamforming technique that exhibits performance similar to an optimal precoding technique when the number of antennas is large (when the reception SNR is high) can be applied so as not to cause high complexity due to many antennas.

1 is a diagram illustrating a cooperative based multi-antenna system according to an embodiment of the present invention.

<Collaborative Multi-Antenna System>

Referring to FIG. 1, a process of cooperating transmission of two transmitting devices to two receiving devices is shown. In FIG. 1, the number of transmitting apparatuses and receiving apparatuses is merely an example, and is not limited thereto. The transmitting apparatus described below may correspond to the base station, and the receiving apparatus may correspond to the user terminal, but the present invention is not limited thereto.

개 안테나를 가지며 각 수신 장치는 한 개의 안테나를 가진다고 가정한다. 이하에서 설명되는 수식을 간단히 하기 위하여, 한 주파수 자원에서 협력 기반의 송신 장치는 2 개의 수신 장치를 지원한다고 가정한다. 그러나, 본 발명에서 송신 장치와 수신 장치의 수는 한정되지 않는다.In the cooperative transmission system, it is assumed that channel information and transmission signals between all transmission devices and reception devices are completely known. Each transmitting device

It is assumed that each antenna has one antenna and each receiving device has one antenna. In order to simplify the formulas described below, it is assumed that a cooperative-based transmitting apparatus in one frequency resource supports two receiving apparatuses. However, the number of transmitting apparatuses and receiving apparatuses is not limited in the present invention.

The transmission signal is transmitted together by the two transmission devices 101 and 102. At this time, it is assumed that the signals transmitted from the transmitting apparatuses 101 and 102 through the timing-advanced mechanism technique are received at the receiving apparatus 103 at the same time. Then, a received signal of the k-th receiving apparatus among the plurality of receiving apparatuses is expressed by Equation (1).

는 각각 k번째 수신 장치에 전송되는 전송 신호를 의미한다. 그리고,

는 j번째 (j =1,2) 전송 장치에서 k번째(k=1, 2) 수신 장치를 위해 실행되는 빔포밍 벡터 (vector) 이다. 그리고

는 j번째 전송 장치에서 k　번째 수신 장치에 전송되는 신호의 전송 파워를 나타낸다.　here,

Denotes a transmission signal transmitted to the k &lt; th &gt; And,

Is a beamforming vector that is run for the kth (k = 1,2) receiver at the jth (j = 1,2) transmitter. And

Represents the transmission power of a signal transmitted from the j &lt; th &gt; transmission apparatus to the k &lt; th &gt;

는 평균값이 0이고 공분산 배열인

는 부가 백색 가우스 잡음 (AWGN: Additive White Gaussian Noice) 값이다. 그리고,

는 j번째 송신 장치와 k번째 수신 장치 간의 채널 벡터이며, 0의 평균과 1의 분산을 가지는 복소수 가우시안 (Gaussian) 벡터이다. 본 발명에서 각 송신 장치와 수신 장치 간의 채널은 모두 독립적이며 플랫(flat)하다고 가정한다.Also,

The average value is 0 and the covariance matrix

Is an Additive White Gaussian Noise (AWGN) value. And,

Is a channel vector between the jth transmitter and the kth receiver and is a complex Gaussian vector with an average of zero and a variance of one. In the present invention, it is assumed that the channel between each transmitting apparatus and the receiving apparatus is independent and flat.

<Linear Zero-Forcing beamforming scheme>

와 전송 파워

가 추출될 수 있다. 본 발명에서 다루는 전송 파워의 최소화 문제를 공식화 하면 하기 수학식 2와 같다.In a cooperative massive multi-antenna system according to an embodiment of the present invention, all the beams that can satisfy the signal-interference-to-noise ratio (SINR) of each receiving apparatus and the power limitation condition of each transmitting apparatus, Forming vector

And transmission power

Can be extracted. The problem of minimizing the transmission power handled in the present invention can be expressed by the following equation (2).

는 각각 k번째 수신 장치의 타겟 SINR을 의미하다. 즉,

는 k번째 수신 장치의 타겟 품질 정보를 의미하며, QoS로 표현될 수 있다. 또한,

는 j번째 송신 장치에서 이용 가능한 전송 파워를 나타낸다. here

Denotes the target SINR of the k &lt; th &gt; receiver. In other words,

Denotes the target quality information of the k &lt; th &gt; receiving apparatus, and can be expressed by QoS. Also,

Represents the transmit power available at the j &lt; th &gt; transmitter.

In this case, the SINR of the k &lt; th &gt;

Since the cooperative massive multi-antenna system in the present invention adopts many antennas, it is necessary to derive an optimal cooperative beam-forming vector design. We support multiple receivers using a linear zero-forcing (ZF) cooperative beamforming vector, which is the simplest and most suitable for near-best performance when the number of antennas is large.

가 j번째 송신 장치에서 각각의 수신 장치들에 지원하는 빔포밍 벡터를 열 벡터로 가지는 매트릭스라고 가정한다. 즉

로 표현될 수 있다. At this time,

Is a matrix having a column vector as a beamforming vector supported by each receiving apparatus in the j-th transmitting apparatus. In other words

. &Lt; / RTI &gt;

는 하기 수학식 4로 표현될 수 있다.Then, a linear zero-forcing based beamforming matrix

Can be expressed by the following equation (4).

는 j번째 송신 장치와 모든 수신 장치들 간의 채널 매트릭스를 나타낸다. 제로 포싱 기반의 빔포밍 벡터를 이용하면 각 수신 장치 간의 간섭이 제거될 수 있다. 그러면, 수학식 1에서 k번째 수신 장치의 수신 신호는 하기 수학식 5와 같이 표현될 수 있다. here

Represents a channel matrix between the j &lt; th &gt; transmitting apparatus and all receiving apparatuses. Using zero-forcing based beamforming vectors, the interference between each receiving device can be eliminated. In Equation (1), the reception signal of the k &lt; th &gt; reception apparatus can be expressed as Equation (5).

Then, Equation (3) can be expressed by Equation (6) below.

Substituting Equations (4), (5), and (6) into Equation (2), Equation (2), which is a problem of minimizing the transmission power, can be expressed by Equation (7).

In this case, k denotes a transmitting apparatus and j denotes a receiving apparatus. In the present invention, the number of transmitting apparatuses (BS) and receiving apparatuses (Rx) is assumed to be two, but the present invention is not limited thereto.

과 송신 장치에서 이용 가능한

의 값에 따라 두 가지 경우로 구분될 수 있다.Since the beamforming vector is fixed in Equation (7), a method of distributing the transmission power corresponding to each beamforming vector is needed in order to minimize the transmission power of the transmitting apparatus. A method for distributing transmit power is based on a target SINR

And a transmitter

The value of the parameter can be divided into two cases.

가 충분할 경우(1) CASE 1: transmit power available at the transmitting apparatus

Is sufficient

Specifically, this means that the use restriction power is sufficient in all transmitting apparatuses in the transmitting apparatus. In other words, CASE 1 means that the transmission power actually used by each transmission apparatus is smaller than the transmission power available at each transmission apparatus. At this time, the transmission power at the transmitting apparatus is expressed by the following equation (8).

), 상기 j번째 송신 장치와 다른 송신 장치와 k번째 수신 장치 간의 빔포밍 벡터(

) 및 타겟 품질 정보(

)를 이용하여 j번째 송신 장치에 할당될 전송 파워가 결정될 수 있다.That is, according to Equation (8), a beamforming vector between the j &lt; th &gt; transmitting apparatus and the k &

), A beamforming vector between the j-th transmitting apparatus and another transmitting apparatus and the k-th receiving apparatus (

) And target quality information (

) May be used to determine the transmission power to be allocated to the j &lt; th &gt;

Here, the condition for deriving Equation (8) is a case where the transmission power available in the transmitting apparatus is sufficient, which can be expressed by Equation (9).

가 불충분할 경우(2) CASE 2: transmit power available at the transmitting apparatus

Is insufficient

Specifically, CASE 2 means a case where the available transmission power is insufficient in at least one of the transmission apparatuses. In other words, CASE 2 indicates that the actual transmission power at each transmission apparatus is equal to or greater than the transmission power available at each transmission apparatus. That is, CASE 2 consumes all of the available transmission power of the transmission apparatus with insufficient available transmission power and satisfies the target SINR of each reception apparatus by consuming the transmission power that is insufficient by the other transmission apparatuses having sufficient available transmission power Respectively.

As described above, in case of CASE 2, since there are many complicated constraints, it is not easy to find the transmission power distribution technique to minimize the transmission power of the total transmission apparatus. However, considering the characteristics of the cooperative massive multi-antenna system, it is possible to efficiently allocate the transmission power in the transmission apparatus.

의 특성이 도출된다. 그러면, 선형 제로 포싱 기반의 빔포밍 벡터는

이 된다. 그리고, 각 채널 벡터

의 norm 값은 대수의 법칙에 의해 거의 같기 때문에 모든 빔포밍 벡터의 norm 값 또한 거의 같다. 즉,

이며 여기서 j은 어떤 상수 값이 된다.Specifically, when a law of large numbers is applied in a massive multi-antenna system,

. Then, the linear zero-forcing based beamforming vector is

. Then, each channel vector

The norm values of all the beamforming vectors are almost the same because the norm values of the beamforming vectors are almost the same by the law of the logarithm. In other words,

Where j is some constant value.

번째 () 송신 장치에서 이용 가능한 전송 파워가 불충분하다고 가정할 때, k번째 수신 장치를 위해 j번째 송신 장치에서 사용되는 전송 파워는 하기 수학식 10과 같이 결정될 수 있다.Also,

Assuming that the transmit power available at the () transmitting device is insufficient, the transmit power used at the j &lt; th &gt; transmitting device for the k &lt; th &gt;

), 상기 j번째 송신 장치와 다른 송신 장치와 k번째 수신 장치 간의 빔포밍 벡터(

), 타겟 품질 정보(

) 및 j번째 송신 장치와 다른 송신 장치에 할당되는 전송 파워(

)를 이용하여 j번째 송신 장치에 할당될 전송 파워가 결정될 수 있다.That is, according to Equation (8), a beamforming vector between the j &lt; th &gt; transmitting apparatus and the k &

), A beamforming vector between the j-th transmitting apparatus and another transmitting apparatus and the k-th receiving apparatus (

), Target quality information (

) And the transmission power allocated to the j th transmission apparatus and other transmission apparatuses (

) May be used to determine the transmission power to be allocated to the j &lt; th &gt;

2 is a flowchart showing a transmission power determination method according to an embodiment of the present invention.

The transmission power determination method described in Figs. 2 to 4 can be performed in the transmission power determination apparatus. Optionally, the transmission power determination device may be located inside or outside the transmission device. 2 to 4, a plurality of transmission apparatuses constitute a multi-antenna system for cooperatively transmitting to each of a plurality of reception apparatuses.

In step 201, the transmission power determination apparatus can set the power limitation condition of the j-th transmission apparatus and the transmission quality information of the k-th reception apparatus. Here, the power limitation condition means the power available in the j-th transmission apparatus. The transmission quality information is QoS information when a signal is transmitted to the kth receiving device and can be expressed by SINR.

In step 202, the transmission power determination unit may determine the transmission power to be allocated to the j-th transmission apparatus when the j-th transmission apparatus transmits data to the k-th reception apparatus using the power limitation condition and transmission quality information. For example, the transmission power determination apparatus may determine a transmission power to be allocated to a j-th transmission apparatus using a beamforming vector when the j-th transmission apparatus transmits data to the k-th reception apparatus. Here, the beamforming vector may be a zero-forcing based beamforming vector. Then, the transmission quality information can be determined based on the beamforming vector applied to the k &lt; th &gt; receiving apparatus and the transmission power to be allocated to the j &lt; th &gt;

For example, the transmission power determination apparatus may determine the transmission power according to whether or not the transmission power to be allocated to the j-th transmission apparatus satisfies the power limitation condition of the j-th transmission apparatus.

Specifically, when the transmission power to be allocated to the j-th transmission apparatus satisfies the power limitation condition of the j-th transmission apparatus, the transmission power determination apparatus determines a beamforming vector between the j-th transmission apparatus and the k-th reception apparatus, The transmission power to be allocated to the j &lt; th &gt; transmitting apparatus can be determined using the beamforming vector and the target quality information between the other transmitting apparatus and the k &lt; th &gt; If the transmission power to be allocated to the j-th transmission apparatus satisfies the power limitation condition of the j-th transmission apparatus, the transmission power determination apparatus may determine the transmission power of the j-th transmission apparatus according to Equation (8).

On the contrary, when the transmission power to be allocated to the j-th transmission apparatus does not satisfy the power limitation condition of the j-th transmission apparatus, the transmission power determination apparatus determines the beamforming vector between the j-th transmission apparatus and the k- The transmission power to be allocated to the j &lt; th &gt; transmitting apparatus can be determined using the beamforming vector between the other transmitting apparatus and the k &lt; th &gt; receiving apparatus, the target quality information, and the transmission power allocated to the j & If the transmission power to be allocated to the j-th transmission apparatus does not satisfy the power limitation condition of the j-th transmission apparatus, the transmission power determination apparatus may determine the transmission power of the j-th transmission apparatus according to Equation (10).

In addition, according to an embodiment of the present invention, the transmission power to the transmission apparatus may be determined by a number of transmission apparatuses, a number of antennas of the transmission apparatus, a number of antennas of the reception apparatus, a channel size generated between the transmission apparatus and the reception apparatus, SINR &lt; / RTI &gt;

3 is a diagram illustrating a transmission power determination method according to another embodiment of the present invention.

In step 301, the transmission power determination apparatus can set the maximum power available in the j-th transmission apparatus.

In step 302, the transmission power determination device may set target quality information associated with the k &lt; th &gt; Here, the target quality information may mean a target SINR.

In step 303, the transmission power determination apparatus may determine the minimum transmission power to be allocated to the jth transmission apparatus in consideration of the maximum power and the target quality information. At this time, the transmission power determination apparatus can determine the minimum transmission power to be allocated to the j-th transmission apparatus when a zero-forcing-based beamforming vector is applied to the k-th reception apparatus.

For example, the transmission power determination apparatus may determine the transmission power according to whether or not the transmission power to be allocated to the j-th transmission apparatus satisfies the maximum power of the j-th transmission apparatus.

Specifically, when the transmission power to be allocated to the j-th transmission apparatus is smaller than the maximum power of the j-th transmission apparatus, the transmission power determination apparatus determines a beamforming vector between the j-th transmission apparatus and the k- The transmission power to be allocated to the jth transmitting apparatus can be determined using the beamforming vector and the target quality information between the apparatus and the kth receiving apparatus. For example, if the transmission power to be allocated to the jth transmission apparatus is smaller than the maximum power of the jth transmission apparatus, the transmission power determination apparatus can determine the transmission power of the jth transmission apparatus according to Equation (8).

On the other hand, when the transmission power to be allocated to the j-th transmission apparatus is equal to or greater than the maximum power of the j-th transmission apparatus, the transmission power determination apparatus determines the beamforming vector between the j- The transmission power to be allocated to the j &lt; th &gt; transmitting apparatus may be determined using the beamforming vector between the transmitting apparatus and the k &lt; th &gt; receiving apparatus, the target quality information, and the transmission power allocated to the j & For example, if the transmission power to be allocated to the j-th transmission apparatus is equal to or greater than the maximum power of the j-th transmission apparatus, the transmission power determination apparatus can determine the transmission power of the j-th transmission apparatus according to Equation (10).

4 is a diagram illustrating a transmission power determination method according to another embodiment of the present invention.

In step 401, the transmission power determination device may set a zero-forcing based beamforming vector associated with the kth receiving device.

In step 402, the transmission power determination apparatus may determine a minimum transmission power to be allocated to the jth transmission apparatus corresponding to the beamforming vector of the kth reception apparatus. For example, the transmission power determination apparatus may determine the minimum transmission power to be allocated to the jth transmission apparatus by comparing the maximum power with the transmission power to be allocated to the jth transmission apparatus. Then, the transmission power determination unit may determine the minimum transmission power to be allocated to the jth transmission apparatus in consideration of the target quality information associated with the kth reception apparatus.

FIG. 5 is a diagram illustrating a total transmission power according to the number of antennas of a transmitting apparatus, according to an embodiment of the present invention.

According to an embodiment of the present invention, a cooperative transmission-based multiple input multiple output (MIMO) system in a downlink (DL) is a system in which a per-base power constraint of a transmission apparatus and a quality of service A method for minimizing the transmission power of a transmitting apparatus is provided. At this time, a Zero-Forcing-based beamforming technique may be selected as the beamforming technique of the transmitting apparatus.

FIG. 5 shows that the total transmission power of a massive multi-antenna system based on cooperative transmission based on zero-forcing beamforming is superior to the transmission power of other systems. The x-axis represents the number of antennas of the transmitting apparatus, and the y-axis represents the sum of the transmission powers used when transmitting signals from all transmitting apparatuses (BSs).

FIG. 5 illustrates a non-cooperative BS in mulitcell in a multi-cell, a cooperative BS based ZF in a beamforming scheme based on a linear zero-forcing scheme, and an upper we compared the total transmission power of a single cell system (Optimal beamforming in single cell) of an optimal beamforming design set to bound. Hereinafter, the first system, the cooperative system with beam-forming design based on linear zero-forcing, the second system, and the single-cell system with optimal beam-forming design are set as the third system.

The number of antennas of a single cell system set to an upper bound is the sum of the number of antennas of each of transmitting apparatuses in multiple cells. Without consideration of path loss in the channel condition, there is no transmit power constraint available in each transmitting device considered in a multi-cell system in a single cell system. This implies that the system applying the transmission power optimization technique can intuitively be set to the upper bound of the multi-cell cooperative system. As a simulation parameter, the target SINR of each receiving device is specified as 10, 50dB and the available transmission power of each BS is 50W.

As can be seen from FIG. 5, the larger the number of antennas, the less the difference between the second system and the third system. The larger the number of antennas, the larger the SINR value of the receiving apparatus. Then, when the SINR of the receiving apparatus is infinite, the zero-forcing-based beamforming scheme is an optimal transmission power allocation scheme, so that there is little difference between the second and third systems as the number of antennas increases.

However, the third system has a beamforming design at a fixed transmission power. Then, the transmission power is redistributed in the fixed beamforming and the method is repeatedly performed until the transmission power and beamforming converge to design beamforming and transmission power distribution. Therefore, as the number of antennas increases, the performance of the second system having a low complexity and the performance difference between the third system having a high complexity hardly differ, so that it can be seen that the second system, which is an embodiment of the present invention, is superior.

6 is a diagram illustrating a probability based on available transmit power of a transmitting apparatus, in accordance with an embodiment of the present invention.

FIG. 6 shows that a cooperative system in which beamforming is applied based on a zero-forcing can be realized even under a more restrictive condition as compared with other systems. The x-axis represents the power available at the transmitting device for which the available transmission power is not fixed. The y-axis represents the outage probability that is not feasible under the constraint condition. FIG. 6 is a graph illustrating the outage probability of a system that does not cooperate in multiple cells and a cooperative system that has a beamforming design based on a linear zero-forcing as transmission power available in other transmission apparatuses increases, Respectively.

The condition that can not be realized here is that the system can not satisfy the constraint by any method in each system. In this simulation parameter, the target SINR of each user is 20dB, the number of antennas of each BS is 100, and the transmission power of a fixed transmission device (BS) is 10W.

As can be seen from FIG. 6, it can be seen that the cooperative multi-antenna system employing the beam-forming scheme based on the linear zero-forcing approaches the outage probability at a lower available power than the system not cooperating in multiple cells. This indicates that a cooperative multi-antenna system employing a linear zero-forcing-based beamforming scheme can satisfy all constraints even at lower transmission power. That is, a cooperative multi-antenna system with linear zero-forcing based beamforming is more feasible than a non-cooperative system.

The methods according to embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

101: transmitting apparatus (BS1)
102: transmitting apparatus (BS2)
103: Receiving device (Rx1)
104: Receiving device (Rx2)

Claims (33)

A method for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Setting target quality information of the receiving apparatus including a power limitation condition of a transmitting apparatus and a signal quality associated with noise and interference with a signal transmitted to the receiving apparatus; And
Determining transmission power to be allocated to the transmitting apparatus when transmitting data to the receiving apparatus based on the power limiting condition and the target quality information
Lt; / RTI &gt;
Wherein the power limitation condition includes power available at the transmitting apparatus,
Wherein the target quality information is a target SINR (Signal-Interference-to-Noise Ratio) of the receiving apparatus,
Method of determining transmission power. The method according to claim 1,
Wherein the determining the transmission power comprises:
And determining a transmission power to be allocated to the transmission apparatus when the transmission apparatus transmits data to the reception apparatus based on a beamforming vector when the transmission apparatus transmits data to the reception apparatus. 3. The method of claim 2,
The beamforming vector is a zero-forcing beamforming vector &lt; RTI ID = 0.0 &gt;
Method of determining transmission power. The method according to claim 1,
Determining transmission quality information of the receiving apparatus based on a beamforming vector when the transmitting apparatus transmits data to the receiving apparatus and the transmitting power allocated to the transmitting apparatus when transmitting data to the receiving apparatus
/ RTI &gt; further comprising the step of: The method according to claim 1,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device; And
Determining the transmit power allocated to the transmitting apparatus that transmits data to the receiving apparatus based on whether the total transmit power allocated to the transmitting apparatus satisfies the power limitation condition
/ RTI &gt; 6. The method of claim 5,
Wherein the step of determining the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus comprises:
A beamforming vector when the transmitting apparatus transmits data to the receiving apparatus, a beam forming vector when the transmitting apparatus different from the transmitting apparatus transmits data to the receiving apparatus, and the total transmission power allocated to the transmitting apparatus, Determining transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus based on the target quality information when the power limitation condition is satisfied
/ RTI &gt; 6. The method of claim 5,
Wherein the step of determining the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus comprises:
Determining, when the total transmission power allocated to the transmitting apparatus satisfies the power limitation condition, the transmission power allocated to the transmitting apparatus that transmits data to the receiving apparatus based on Equation
[Equation 1]

Lt; / RTI &gt;
Here, P _kj denotes the transmission power allocated to the transmission apparatus for transmitting data to the receiving unit, j denotes the transmission apparatus, j 'denotes the other transmitting device and the transmitting device, k is the received W _kj denotes a beamforming vector when the transmitting apparatus transmits data to the receiving apparatus, W _{kj '} denotes a beam forming vector when the other transmitting apparatus transmits data to the receiving apparatus, W _kj'

Lt; RTI ID = 0.0 &gt; target &
Method of determining transmission power. 6. The method of claim 5,
Wherein the step of determining the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus comprises:
A beamforming vector when the transmitting apparatus transmits data to the receiving apparatus when the total transmission power to be allocated to the transmitting apparatus does not satisfy the power limiting condition; A transmission power allocated to the transmission apparatus based on a beamforming vector when the data is transmitted, the target quality information, and transmission power allocated when the other transmission apparatus transmits data to the reception apparatus, Determining power
And determining a transmit power to be included. 6. The method of claim 5,
Wherein the step of determining the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus comprises:
Determining a transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus based on Equation (2) below when the total transmission power allocated to the transmitting apparatus does not satisfy the power limiting condition
&Quot; (2) &quot;

Lt; / RTI &gt;
Where p _kj denotes the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus, k denotes the receiving apparatus, j denotes the transmitting apparatus, j ' denotes a device, || W || _kj denotes a beamforming vector of when the transmitting device to the receiving device to send data, || W _{kj '||} is the other the transmission device to the reception device to transmit data Beamforming vector,

P _{kj '} represents the transmission power allocated when the other transmitting apparatus transmits data to the receiving apparatus,
Method of determining transmission power. 6. The method of claim 5,
Wherein determining the total transmit power allocated to the transmitting device comprises:
A beam forming vector when the transmitting apparatus transmits data to the receiving apparatus, a beam forming vector when the transmitting apparatus other than the transmitting apparatus transmits data to the receiving apparatus, and the target quality information, Lt; RTI ID = 0.0 &gt;
And determining a transmit power to be included. delete A method for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Setting a maximum available power of the transmitting apparatus;
Setting target quality information of the receiving apparatus including signal quality associated with noise and interference with a signal transmitted to the receiving apparatus; And
Determining transmission power to be allocated to the transmitting apparatus when transmitting data to the receiving apparatus based on the maximum power and target quality information
Lt; / RTI &gt;
A power limitation condition which is an available transmission power of the transmission apparatus is determined based on a maximum power of the transmission apparatus,
Wherein the target quality information is a target SINR (Signal-Interference-to-Noise Ratio) of the receiving apparatus,
Method of determining transmission power. 13. The method of claim 12,
Wherein the determining the transmission power comprises:
And determining a transmission power to be allocated to the transmission apparatus when the transmission apparatus transmits data to the reception apparatus based on a zero forcing beamforming vector when the transmission apparatus transmits data to the reception apparatus. 13. The method of claim 12,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device; And
A beamforming vector when the transmitting device transmits data to the receiving device when the total transmitting power allocated to the transmitting device is less than or equal to the maximum power, a beamforming vector when another transmitting device transmits data to the receiving device Determining a transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus based on the beamforming vector and the target quality information
/ RTI &gt; 13. The method of claim 12,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device; And
Determining, if the total transmission power allocated to the transmission apparatus is less than or equal to the maximum power, the transmission power allocated to the transmission apparatus that transmits data to the reception apparatus based on Equation
&Quot; (3) &quot;

Lt; / RTI &gt;
Here, P _kj denotes the transmission power allocated to the transmission apparatus for transmitting data to the receiving unit, j denotes the transmission apparatus, j 'denotes the other transmitting device and the transmitting device, k is the received W _kj denotes a beamforming vector when the transmitting apparatus transmits data to the receiving apparatus, W _{kj '} denotes a beam forming vector when the other transmitting apparatus transmits data to the receiving apparatus, W _kj'

Lt; RTI ID = 0.0 &gt; target &
Method of determining transmission power. 13. The method of claim 12,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device; And
A beamforming vector when the transmitting device transmits data to the receiving device when the total transmitting power allocated to the transmitting device is larger than the maximum power, a transmitting device different from the transmitting device transmitting data to the receiving device Determining a transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus based on a beamforming vector when the transmitting apparatus transmits data to the receiving apparatus and a transmission power allocated when the transmitting apparatus transmits data to the receiving apparatus
/ RTI &gt; 13. The method of claim 12,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device; And
Determining, if the total transmission power allocated to the transmission apparatus is greater than the maximum power, the transmission power allocated to the transmission apparatus that transmits data to the reception apparatus based on Equation (4) below
&Quot; (4) &quot;

Lt; / RTI &gt;
Where p _kj denotes the transmission power allocated to the transmitting apparatus for transmitting data to the receiving apparatus, k denotes the receiving apparatus, j denotes the transmitting apparatus, j ' denotes a device, || W || _kj denotes a beamforming vector of when the transmitting device to the receiving device to send data, || W _{kj '||} is the other the transmission device to the reception device to transmit data Beamforming vector,

P _{kj '} represents the transmission power allocated when the other transmitting apparatus transmits data to the receiving apparatus,
Method of determining transmission power. A method for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Setting target quality information of the receiving device including a zero forcing beamforming vector associated with the receiving device and a signal quality associated with noise and interference to the signal transmitted to the receiving device; And
Determining a transmission power to be allocated to a transmitting apparatus that transmits data to the receiving apparatus based on the zero forcing beamforming vector and the target quality information
Lt; / RTI &gt;
Wherein the target quality information is a target SINR (Signal-Interference-to-Noise Ratio) of the receiving apparatus,
Method of determining transmission power. 19. The method of claim 18,
Wherein the determining the transmission power comprises:
Determining a total transmit power allocated to the transmitting device;
Comparing the maximum power available to the transmitting apparatus with the total transmitting power allocated to the transmitting apparatus; And
Determining a transmission power to be allocated to a transmitting apparatus that transmits data to the receiving apparatus based on the comparison result
/ RTI &gt; An apparatus for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Wherein the transmission power determination apparatus includes at least one processor,
The processor comprising:
Setting the target quality information of the receiving apparatus including the power limitation condition of the transmitting apparatus and the signal quality related to noise and interference with respect to the signal transmitted to the receiving apparatus,
Determines a transmission power to be allocated to the transmitting apparatus when transmitting the data to the receiving apparatus based on the power limiting condition and the target quality information,
Wherein the power limitation condition includes power available at the transmitting apparatus,
Wherein the target quality information is a target SINR (Signal-Interference-to-Noise Ratio) of the receiving apparatus,
Transmission power determination device. 21. The method of claim 20,
The processor comprising:
And determines a transmission power to be allocated to the transmission apparatus when the transmission apparatus transmits data to the reception apparatus based on a beamforming vector when the transmission apparatus transmits data to the reception apparatus. 22. The method of claim 21,
The beamforming vector is a zero-forcing beamforming vector &lt; RTI ID = 0.0 &gt;
Transmission power determination device. 21. The method of claim 20,
The processor comprising:
Determines transmission quality information of the receiving apparatus based on a beamforming vector when the transmitting apparatus transmits data to the receiving apparatus and the transmission power allocated to the transmitting apparatus when transmitting data to the receiving apparatus
Transmission power determination device. 21. The method of claim 20,
The processor comprising:
Determining a total transmission power allocated to the transmitting apparatus,
Determining the transmission power allocated to the transmitting apparatus that transmits data to the receiving apparatus based on whether the total transmitting power allocated to the transmitting apparatus satisfies the power limitation condition
Transmission power determination device. 25. The method of claim 24,
The processor comprising:
A beamforming vector when the transmitting apparatus transmits data to the receiving apparatus, a beam forming vector when the transmitting apparatus different from the transmitting apparatus transmits data to the receiving apparatus, and the total transmission power allocated to the transmitting apparatus, Determining a transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus based on the target quality information when the power limitation condition is satisfied
Transmission power determination device. 25. The method of claim 24,
The processor comprising:
A beam forming vector when the transmitting apparatus transmits data to the receiving apparatus, a beam forming vector when the transmitting apparatus other than the transmitting apparatus transmits data to the receiving apparatus, and the target quality information, Lt; RTI ID = 0.0 &gt;
Transmission power determination device. delete An apparatus for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Wherein the transmission power determination apparatus includes at least one processor,
The processor comprising:
Sets available transmit power of the transmitting apparatus,
Setting target quality information of the receiving apparatus including signal quality related to noise and interference with respect to a signal transmitted to the receiving apparatus,
Determine transmission power to be allocated to the transmitting apparatus when transmitting data to the receiving apparatus based on the available transmission power and target quality information,
Wherein the available transmit power of the transmitting apparatus is determined based on a maximum power of the transmitting apparatus,
Transmission power determination device. 29. The method of claim 28,
The processor comprising:
The transmission power allocated to the transmitting apparatus when the transmitting apparatus transmits data to the receiving apparatus based on a zero forcing beamforming vector when the transmitting apparatus transmits data to the receiving apparatus is determined
Transmission power determination device. 29. The method of claim 28,
The processor comprising:
Determining a total transmission power allocated to the transmitting apparatus,
A beamforming vector when the transmitting device transmits data to the receiving device when the total transmitting power allocated to the transmitting device is greater than the available transmitting power; And a transmission power allocated when the other transmitting apparatus transmits data to the receiving apparatus, determines a transmission power to be allocated to the transmitting apparatus that transmits data to the receiving apparatus
Transmission power determination device. delete An apparatus for determining transmission power of each of a plurality of transmission apparatuses in a multi-input multi-output (MIMO) system in which a plurality of transmission apparatuses transmit data to a plurality of reception apparatuses,
Wherein the transmission power determination apparatus includes at least one processor,
The processor comprising:
Setting target quality information of the receiving apparatus including a zero forcing beamforming vector associated with the receiving apparatus and a signal quality associated with noise and interference with signals transmitted to the receiving apparatus,
Determining a transmission power to be allocated to a transmitting apparatus that transmits data to the receiving apparatus based on the zero-forcing beamforming vector and the target quality information,
Wherein the target quality information is a target SINR (Signal-Interference-to-Noise Ratio) of the receiving apparatus,
Transmission power determination device. 33. The method of claim 32,
The processor comprising:
Determining a total transmission power allocated to the transmitting apparatus,
Comparing transmission power available to the transmission apparatus with total transmission power allocated to the transmission apparatus,
And determines a transmission power to be allocated to a transmitting apparatus that transmits data to the receiving apparatus based on the comparison result
Transmission power determination device.

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