KR102246764B1 - Method for improving beamforming perfomance of base station and control device using the same - Google Patents

Abstract

The present invention relates to a method for improving beamforming performance in a base station that improves beamforming performance by determining an optimal 5G feedback scheme in consideration of uplink signal strength, number of terminals, and movement speed of terminals, and a control apparatus for performing the same. , More specifically, the base station sets channel feedback information for beamforming received from the terminal based on the uplink signal strength of the terminal as SRS (Sounding Reference Signal) or PMI (Precoding Matrix Index), and the number of terminals in the base station The transmission method of the channel feedback information is selected in a periodic or aperiodic method based on and proceeds, and the transmission period of the channel feedback information set based on the moving speed and coherence time of the terminal in the base station is reset. The present invention relates to a method for improving beamforming performance in a base station configured to be adjusted once to proceed, and a control apparatus for performing the same.

Description

A method for improving beamforming performance in a base station, and a control device for performing the same TECHNICAL FIELD [METHOD FOR IMPROVING BEAMFORMING PERFOMANCE OF BASE STATION AND CONTROL DEVICE USING THE SAME}

The present invention relates to a method for improving beamforming performance in a base station and a control device for performing the same. In particular, by determining an optimal 5G feedback scheme in consideration of uplink signal strength, number of terminals, and movement speed of terminals, The present invention relates to a method for improving beamforming performance in a base station with improved performance, and a control apparatus for performing the same.

In general, since the base station receives channel feedback information from the terminal and performs precoding for beamforming, the channel feedback information greatly affects the beamforming performance.

Accordingly, since channel feedback information cannot be demodulated normally in a weak field region, a problem of performance degradation of beamforming may occur due to an error in channel feedback information.

Also, depending on the transmission period of the channel feedback (PMI: Precoding Matrix Index / SRS: Sounding Reference Signal) information and the channel feedback information, there is a limitation on the number of terminals that can be simultaneously supported. Since information cannot be received, a problem of beamforming performance degradation may occur.

In addition, even when the transmission period of the channel feedback information is set for a long time, since the change of the radio channel according to the movement and the movement speed of the terminal cannot be properly reflected, a problem of performance degradation of beamforming may occur.

(0001) Korean Patent Application Publication No. 10-2013-0095230 (0002) Domestic registered patent No. 10-1674960

The technical problem to be solved by the present invention is a base station configured to transmit channel feedback information for beamforming as a sounding reference signal (SRS) or a precoding matrix index (PMI) based on the strength of an uplink signal of a terminal in a base station. It is to provide a method for improving beamforming performance and a control device for performing the same.

Another technical problem to be solved by the present invention is a method of improving beamforming performance in a base station configured to proceed by selecting a transmission method of channel feedback information in a periodic or aperiodic manner based on the number of terminals in the base station And it is to provide a control device for performing this.

Another technical problem to be solved by the present invention is to provide a method for improving beamforming performance in a base station and a control device for performing the same. It is in providing.

Another technical problem to be solved by the present invention is a method for improving beamforming performance in a base station configured to determine a moving speed of a terminal by utilizing the Doppler effect when the base station does not have location information of the terminal, and a control for performing the same It is in providing the device.

Another technical problem to be solved by the present invention is in a base station configured to calculate a coherence time using a moving speed of a terminal and transmit channel feedback information within a coherence time having a good channel state. It is to provide a method for improving beamforming performance and a control device for performing the same.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. I will be able to.

According to an embodiment of a method for improving beamforming performance in a base station according to the present invention for achieving the above technical problem, in the method for improving beamforming performance in a base station for at least one terminal connected to a base station through a communication channel, the communication for each terminal Determining an environment, and determining a transmission method of channel feedback information transmitted from the terminal to the base station for beamforming according to the identified communication environment for each terminal; And receiving channel feedback information transmitted from the terminal according to the determined channel feedback information transmission method.

Here, the communication environment includes the number of terminals connected to the base station, an uplink signal strength of channel feedback information transmitted from the terminal to the base station, and a movement speed of the terminal, and the movement speed of the terminal is optionally included. It is done.

In addition, the determining of the channel feedback information transmission method may include determining the number of terminals connected to the base station through a communication channel; Setting a transmission period of channel feedback information transmitted from the terminal based on the identified number of terminals; Measuring the strength of an uplink signal for each terminal based on the channel feedback information transmitted from the terminal; And setting channel feedback information to be transmitted from the terminal through the determined number of terminals and the measured strength of the uplink signal for each terminal.

Here, the step of estimating a movement speed for each terminal based on the channel feedback information transmitted from the terminal; characterized in that it further comprises.

In this case, the movement speed for each terminal is calculated based on a Doppler shift for channel feedback information transmitted from the terminal, or calculated through a movement distance of the terminal according to time based on the location of the terminal. It is characterized by that.

In addition, a coherence time for each terminal is calculated through the movement speed for each terminal, and a transmission period of channel feedback information set in consideration of the coherence time is increased or decreased.

Meanwhile, a control apparatus according to a method for improving beamforming performance in a base station according to another embodiment of the present invention includes: a communication unit receiving channel feedback information from at least one terminal; And a processing unit that determines a communication environment of a terminal that has transmitted the channel feedback information, selects a channel feedback information transmission method for beamforming, and receives channel feedback information according to the selected channel feedback information transmission method. It is done.

Here, the communication environment includes the number of terminals connected to the base station, an uplink signal strength of channel feedback information transmitted from the terminal to the base station, and a movement speed of the terminal, and the movement speed of the terminal is optionally included. It is done.

In addition, the processing unit determines the number of terminals connected to the base station through a communication channel, sets a transmission period of channel feedback information transmitted from the terminal through the identified number of terminals, and stores channel feedback information transmitted from the terminal. Based on the measurement of the strength of an uplink signal for each terminal, channel feedback information to be transmitted from the terminal is set through the determined number of terminals and the measured strength of the uplink signal for each terminal.

Here, the processing unit is characterized in that it estimates the movement speed for each terminal through the channel feedback information transmitted from the terminal.

In this case, the movement speed for each terminal is calculated based on a Doppler shift for channel feedback information transmitted from the terminal, or calculated through a movement distance of the terminal according to time based on the location of the terminal. It is characterized by that.

In addition, the processing unit may calculate a coherence time for each terminal through the movement speed for each terminal, and increase or decrease a transmission period of the channel feedback information in consideration of the coherence time.

The aspects of the present invention are only some of the preferred embodiments of the present invention, and various embodiments reflecting the technical features of the present invention will be described in detail below by those of ordinary skill in the art. Can be derived and understood based on

A method for improving beamforming performance in a base station according to the present invention and an effect on a control device performing the same will be described below.

First, when the number of terminals is less than the reference value, it is aperiodic, that is, the base station configures to request channel feedback information only when the base station needs channel feedback information, and when the number of terminals is more than the reference value, the channel feedback information is periodic. By configuring it to transmit. It is possible to prevent unnecessary waste of resources due to channel feedback transmission.

In addition, the base station selects SRS (Sounding Reference Signal) as channel feedback information for beamforming when the strength of the uplink signal for each terminal is higher than the reference value, and if it is less than the reference value, the base station selects a Precoding Matrix Index (PMI). Since the influence of the channel estimation error can be reduced, the beamforming performance can be improved as a result.

In addition, when there is no location information of the terminal in the base station, the movement speed of the terminal is determined using the Doppler effect and the channel feedback period is determined based on the movement speed of each terminal, thereby reducing a channel estimation error due to the movement of the terminal.

In addition, by calculating the coherence time through the moving speed of the terminal and setting the transmission period of the channel feedback information within the coherence time in which the channel state is good, the transmission state of the channel feedback information is optimized and is based on this. The performance of beamforming performed by the method may be improved.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those of ordinary skill in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are provided to aid understanding of the present invention, and provide embodiments of the present invention together with a detailed description. However, the technical features of the present invention are not limited to a specific drawing, and features disclosed in each drawing may be combined with each other to constitute a new embodiment.
1 is a diagram for describing a periodic/aperiodic progression step of a method for improving beamforming performance in a base station according to an embodiment.
FIG. 2 is a diagram for describing in more detail a periodic progression step of a method for improving beamforming performance in a base station according to an exemplary embodiment.
3 is a flowchart illustrating a periodic/aperiodic progression step of a method for improving beamforming performance in a base station according to an embodiment.
4 is a conceptual diagram illustrating a control apparatus for performing a method for improving beamforming performance in a base station according to another embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to elements of each drawing, it should be noted that the same elements are assigned the same numerals as possible, even if they are indicated on different drawings. In addition, in describing the embodiments of the present invention, if it is determined that a detailed description of a related known configuration or function obstructs the understanding of the embodiments of the present invention, the detailed description thereof will be omitted.

In addition, in describing the constituent elements of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, the component may be directly connected or connected to that other component, but another component between each component It should be understood that may be “connected”, “coupled” or “connected”.

First, the present invention is applied to a wireless communication system such as an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may be an Evolved-UMTS Terrestrial Radio Access (E-UTRA) or Long Term Evolution (LTE) or advanced (LTE-A) system. Wireless communication systems include Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), and OFDM-FDMA. , OFDM-TDMA, OFDM-CDMA, such as various multiple access techniques can be used.

E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) includes a base station (eNB: evolved NodeB) that provides a control plane (CP) and a user plane (UP: User Plane) to a user equipment (UE). can do.

The terminal may be fixed or mobile, and may be referred to as other terms such as a mobile station (MS), an advanced MS (AMS), a user terminal (UT), a subscriber station (SS), and a wireless device.

A base station generally refers to a station that communicates with a terminal, and BS (Base Station), BTS (Base Transceiver System), Access Point (Access Point), femto base station (femto-eNB), pico base station (pico-eNB) , May be called a different term such as a home base station (Home eNB), a relay, and the like. The base stations are physically connected to each other through an optical cable or DSL (Digital Subscriber Line), and can exchange signals or messages with each other through an X2 or Xn interface.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The present invention is a method for improving beamforming performance in a base station for improving beamforming performance by optimizing channel feedback information transmitted from a terminal to a base station according to the number of terminals, the strength of an uplink signal, and a movement speed of the terminal, and performing the same. It relates to a control device.

1 is a diagram for explaining a step performed periodically/aperiodically according to a method for improving beamforming performance in a base station according to an exemplary embodiment.

A method for improving beamforming performance according to the present invention will be described with reference to FIG. 1 as follows.

In the method for improving beamforming performance of the present inventors, in a method for improving beamforming performance in a base station for at least one terminal connected to a base station through a communication channel, the communication environment for each terminal is identified, and the terminal according to the determined communication environment for each terminal. Including the step of determining a transmission method of channel feedback information transmitted to the base station for beamforming (S10) and receiving the channel feedback information transmitted from the terminal according to the determined channel feedback information transmission method (S20). It is composed.

Here, the communication environment includes the number of terminals connected to the base station, an uplink signal strength of channel feedback information transmitted from the terminal to the base station, and a moving speed of the terminal. In addition, the moving speed of the terminal may be selectively included.

The determining of the channel feedback information transmission method includes determining the number of terminals connected to the base station through a communication channel (S11), and setting a transmission period of the channel feedback information transmitted from the terminal through the determined number of terminals. Step (S12), measuring the strength of the uplink signal for each terminal based on the channel feedback information transmitted from the terminal (S13), and the determined number of terminals and the measured strength of the uplink signal for each terminal. And setting channel feedback information to be transmitted from the terminal (S14).

In the step (S11) of determining the number of terminals, it is determined whether the number of identified terminals is greater than or less than a set reference value (number).

In this case, the number of terminals serving as the reference value may be set by the operator in consideration of the usage environment, that is, the number of terminal users taking into account frequency bandwidth, population density, and floating population.

In the step of setting the transmission period of the channel feedback information (S12), it is determined whether to transmit the channel feedback information periodically or aperiodically according to the identified number of terminals.

Channel feedback information for beamforming is transmitted from the terminal to the base station.

There are a periodic method and an aperiodic method as a transmission periodic method of channel feedback information (hereinafter referred to as'feedback'). The periodic method is a method of transmitting feedback to the base station according to a set period. The aperiodic scheme is a scheme in which the base station requests and receives feedback from the terminal whenever feedback is required.

When the number of terminals is large, a periodic method of transmitting feedback without a separate request is advantageous. However, if feedback is periodically transmitted even when the number of terminals is small, a corresponding resource is wasted, so an aperiodic method of requesting the terminal only when feedback is required is advantageous.

First, a process step in a state in which the transmission period of the feedback is set aperiodically will be described.

When the number of terminals is less than the reference value, the feedback transmission period is aperiodically set.

In the step of measuring the strength of the uplink signal for each terminal (S13), the strength of the uplink signal for each terminal is determined while the feedback transmission period is set aperiodically.

The strength of the uplink signal for each terminal is based on signals received through Sounding Reference Signal (SRS), Physical Uplink Control Channel (PUCCH), and Physical Uplink Shared Channel (PUSCH). to Interference Noise Ratio). For example, in the uplink, the uplink channel state (link loss/interference degree) can be determined by allowing the UE to shoot an SRS of a predetermined power and receive it and measure the received SINR.

In the step of setting the channel feedback information (S14), a feedback type to be transmitted from the terminal to the base station is determined according to the strength of the uplink signal for each terminal.

That is, when the measured strength of the uplink signal per terminal is greater than or equal to the set value, the terminal transmits the first feedback information to the base station, and when the measured strength of the uplink signal per terminal is less than the set value, the terminal is sent to the base station. Transmits the second feedback information.

The first feedback information is a sounding reference signal (SRS) transmitted aperiodically, and the second feedback information is a precoding matrix index (PMI) transmitted aperiodically.

Since the base station receives feedback from the terminal and performs precoding for beamforming, the feedback greatly affects the performance of beamforming. Feedback for beamforming includes a Sounding Reference Signal (SRS) and a Precoding Matrix Index (PMI). SRS is advantageous in beamforming performance due to a large amount of feedback information transmitted by a terminal, but a channel estimation error may occur because the amount of feedback information is small in a weak electric field. Since this can degrade the beamforming performance, in this case, a PMI having less influence due to an estimation error is advantageous.

In the step of receiving the channel feedback information (S20), the feedback transmitted through the above process is received.

In this way, even in a weak electric field, beamforming is performed by optimizing a communication channel from the terminal to the base station and receiving feedback transmitted through the optimized communication channel, thereby improving beamforming performance.

On the other hand, even through FIG. 1, both a state in which the transmission period of the feedback is set aperiodically and a state that is set periodically can be described, but for a more detailed description of the process step, the transmission period of the feedback is periodically set. Let's explain the steps in progress in the state.

FIG. 2 is a diagram for describing in more detail a periodic progression step of a method for improving beamforming performance in a base station according to an exemplary embodiment.

When the number of terminals connected to the base station through a communication channel exceeds the set reference value, the feedback transmission period is set to periodic.

Thereafter, in the step of calculating the movement speed for each terminal (S12-1), calculation based on the uplink received signal, that is, the Doppler shift of the feedback transmitted from the terminal to the base station, or GPS Reporting, E-CID (Exclusive Chip IDentification) and OTDOA are used to calculate the movement speed over time based on the location of the terminal by time received from the base station. E-CID is the same as a resident registration number, and each terminal has its own E-CID. In addition, OTDOA (Observed Time Difference of Arrival) is a method of predicting the location of the terminal based on the delay time until the base station signal arrives at the terminal. OTDOA is a type of standard technology established by 3GPP, a mobile communication standardization organization, and can determine distance information by calculating the delay time until a terminal receives a signal transmitted from a base station.

That is, the Doppler shift is a phenomenon in which the reception frequency deviation occurs due to the movement of the mobile object (terminal), and the frequency deviation due to the Doppler shift increases as the speed of the mobile object increases or the carrier frequency (frequency band) increases. Accordingly, the base station can calculate the speed of the terminal as shown in [Table 1] using the following [Equation 1] based on the Doppler shift of the uplink received signal.

That is, the terminal movement speed is required to determine the channel feedback method, the channel feedback periodic method (Periodic/Aperiodic), and the channel feedback period, and the terminal movement speed estimation method is as shown in [Equation 1] below.

및 빛의 속도

로 단말 이동속도

를 추정한다.Doppler shift value and carrier frequency of the uplink signal transmitted by the terminal to the base station

And the speed of light

Terminal movement speed

Estimate

For example, when a carrier frequency of 3.5GHz is used, the UE movement speed corresponding to each Doppler shift is shown in Table 1 below.

Terminal movement speed (km/h) 3 10 30 60 100 Uplink Doppler Shift(HZ) 9.7 32.4 97.2 194.4 324.1 Remark Carrier Frequency is assumed to be 3.5GHz

After the movement speed calculation step (S12-1) for each terminal, the coherence time calculation step (S12-2) is performed.

In the coherence time calculation step (S12-2), a coherence time is calculated based on the moving speed of the terminal calculated for each terminal. The coherence time refers to a time in the range in which the propagation correlates with a certain time and after Δt time therefrom. That is, since the channel is considered to be good during the corresponding time only when the correlation between the channels is high, performance degradation is small only when the feedback is transmitted within the coherence time according to the terminal movement speed. Since the coherence time is inversely proportional to the Doppler effect and the Doppler effect is proportional to the moving speed of the UE, the coherence time according to the moving speed of the UE is calculated as shown in [Table 2] using the following [Equation 2].

That is, a coherence time is required to determine a channel feedback period, and a method for calculating the coherence time is as shown in [Equation 2] below.

은 coherence coefficient이며, 일반적으로 0.423을 사용한다.

Is the coherence coefficient, and generally 0.423 is used.

, 빛의 속도

및 단말 이동속도

로 추정할 수 있다.Coherence coefficient value is carrier frequency

, Speed of light

And terminal movement speed

It can be estimated as

When a carrier frequency of 3.5GHz is used, the coherence time for each terminal movement speed is shown in [Table 2] below.

Terminal movement speed (km/h) 3 10 30 60 100 Coherence Time(ms) 43.5 13.1 4.4 2.2 1.3 Remark Coherence coefficient is assumed to be 0.423

Thereafter, in the step of measuring the strength of the uplink signal for each terminal (S13), the strength of the uplink signal for each terminal is measured by the above-described method.

In the step of setting the channel feedback information (S14), when the measured strength of the uplink signal for each terminal is greater than or equal to the set value, a periodic SRS, which is the first feedback information, is transmitted to the base station, and the measured strength of the uplink signal for each terminal is the set value If it is less than the second feedback information, periodic PMI is transmitted to the base station.

In determining whether to increase or decrease the set transmission period (S14-1), it is determined whether or not the set transmission period is increased or decreased by comparing the set transmission period with the calculated coherence time.

First, when a periodic SRS is transmitted, if the set transmission period is less than the calculated coherence time, the set transmission period is increased in consideration of the calculated coherence time. In addition, if the set transmission period is greater than or equal to the calculated coherence time, the set transmission period is reduced in consideration of the calculated coherence time.

Next, in case of transmitting a periodic PMI, if the set transmission period is less than the calculated coherence time, the set transmission period is increased in consideration of the calculated coherence time. In addition, if the set transmission period is greater than or equal to the calculated coherence time, the set transmission period is reduced in consideration of the calculated coherence time.

Here, it is preferable to change the increase and decrease of the period within the range of the period defined in 3GPP TS38.331.

As described above, the base station calculates the coherence time based on the movement speed of each terminal, determines a transmission period of the feedback through this, and transmits it to the terminal. The terminal that has received the information on the transmission period of the feedback transmits the feedback to the base station according to the transmitted transmission period, thereby reducing a channel estimation error due to the movement of the terminal.

3 is a flowchart illustrating a periodic/aperiodic progression step of a method for improving beamforming performance in a base station according to the above-described embodiment.

Referring to FIG. 3, a method of improving beamforming performance in a base station according to the present invention will be described as follows.

First, a periodic or aperiodic feedback transmission period for beamforming is determined according to the number of terminals. When the number of terminals is greater than or equal to a predetermined value (Th_1), a periodic transmission of the feedback for beamforming is performed, and when the number of terminals is less than a predetermined value (Th_1), the transmission period of the feedback for beamforming is performed Aperiodic.

When the transmission period of the feedback is performed Aperiodic, the feedback is determined using a sounding reference signal (SRS) or a precoding matrix index (PMI) according to the strength of an uplink signal for each terminal.

When the signal strength of the corresponding terminal is greater than or equal to a predetermined value (Th_2), the corresponding terminal transmits an Aperiodic SRS to the base station. The base station receiving the Aperiodic SRS transmits data by performing beamforming to the corresponding terminal.

When the signal strength of the corresponding terminal is less than a certain value (Th_2), the corresponding terminal transmits an Aperiodic PMI to the base station. The base station receiving the Aperiodic PMI transmits data by performing beamforming to the corresponding terminal.

Meanwhile, when performing periodic, the moving speed of the corresponding terminal is estimated for each terminal. Thereafter, the coherence time (T_UE) is calculated based on the estimated movement speed of each terminal.

Thereafter, it is determined whether to transmit the feedback transmitted to the base station through a sounding reference signal (SRS) or a precoding matrix index (PMI) according to the uplink signal strength of each terminal.

When the signal strength of the corresponding terminal is greater than or equal to a predetermined value (Th_2), the corresponding terminal transmits an SRS to the base station, and when the signal strength of the corresponding terminal is less than a predetermined value (Th_2), the corresponding terminal transmits a PMI to the base station.

First, when transmitting the SRS, the calculated coherence time (T_UE) value is compared with the currently set feedback transmission period to determine whether to increase/decrease the feedback transmission period.

That is, when the coherence time (T_UE) is less than the set feedback transmission period, the transmission period of the periodic SRS to be transmitted to the base station for the corresponding terminal is reduced and transmitted.

The base station receiving the periodic SRS with the reduced transmission period transmits data by performing beamforming to the corresponding terminal.

In addition, when the coherence time (T_UE) is greater than or equal to the set feedback transmission period, the transmission period of the periodic SRS to be transmitted to the base station for the corresponding terminal is increased and transmitted.

The base station receiving the periodic SRS with the increased transmission period transmits data by performing beamforming to the corresponding terminal.

Next, when PMI is transmitted, the calculated coherence time (T_UE) value is compared with the currently set feedback transmission period to determine whether to increase/decrease the feedback transmission period.

That is, when the coherence time (T_UE) is less than the set feedback transmission period, the transmission period of the periodic PMI to be transmitted to the base station for the corresponding terminal is reduced and transmitted.

The base station receiving the periodic PMI with the reduced transmission period transmits data by performing beamforming to the corresponding terminal.

In addition, when the coherence time (T_UE) is greater than or equal to the set feedback transmission period, the transmission period of the periodic PMI to be transmitted to the base station for the corresponding terminal is increased and transmitted.

The base station receiving the periodic PMI with the increased transmission period transmits data by performing beamforming to the corresponding terminal.

4 is a conceptual diagram illustrating a control apparatus for performing a method for improving beamforming performance in a base station according to another embodiment.

Referring to FIG. 4, a control apparatus for performing a method for improving beamforming performance in a base station according to the present invention will be described. The control device may refer to the part described in the above-described method for improving beamforming performance in the base station.

The control apparatus according to the method for improving beamforming performance in the base station 10 according to the present invention is installed in the base station 10 and includes a communication unit 11 and a processing unit 12.

The communication unit 11 receives channel feedback information from at least one terminal 20.

The processing unit 12 determines a communication environment of the terminal 20 that has transmitted the channel feedback information, selects a channel feedback information transmission method for beamforming, and receives channel feedback information according to the selected channel feedback information transmission method. .

Here, the communication environment is the number of terminals 20 connected to the base station 10, the uplink signal strength of the channel feedback information transmitted from the terminal 20 to the base station 10, and the moving speed of the terminal 20 Consists of including. In addition, the moving speed of the terminal 20 may be selectively included.

The processing unit 12 determines the number of terminals 20 connected to the base station 10 through a communication channel. In addition, a transmission period of the channel feedback information transmitted from the terminal 20 is set through the identified number of terminals 20. In addition, the strength of the uplink signal for each terminal 20 is measured based on the channel feedback information transmitted from the terminal 20. In addition, channel feedback information to be transmitted from the terminal 20 is set through the identified number of terminals 20 and the measured strength of the uplink signal for each terminal 20.

The processing unit 12 periodically sets a transmission period of the channel feedback information when the number of the identified terminals 20 is equal to or greater than a set reference value.

In this case, the processing unit 12 estimates a movement speed for each terminal 20 through the channel feedback information transmitted from the terminal 20.

In addition, the movement speed for each terminal 20 is calculated based on a Doppler shift for channel feedback information transmitted from the terminal 20, or the terminal ( It can be calculated through the moving distance over time of 20), and for details, refer to the above description.

In addition, the processing unit 12 may calculate a coherence time for each terminal 20 through the movement speed for each terminal 20, which will also be referred to the above description.

The processing unit 12 receives first feedback information from the terminal 20 when the measured strength of the uplink signal for each terminal 20 is greater than or equal to a set value, and the measured uplink signal for each terminal 20 When the intensity is less than the set value, the second feedback information is transmitted from the terminal 20.

At this time, the strength of the uplink signal for each terminal 20 is RSRP (Reference Signal Received Power) based on signals received through Sounding Reference Signal (SRS), Physical Uplink Control Channel (PUCCH), and Physical Uplink Shared Channel (PUSCH). ) And SINR (Signal to Interference Noise Ratio) can be measured.

Meanwhile, the channel-related feedback information may be transmitted through an uplink data channel or an uplink control channel, for example, a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH). The channel-related information reported by the terminal 20 to the base station 10 includes a channel quality indicator (CQI), a rank indicator (RI), a precoding matrix indicator (PMI), a sounding reference signal (SRS), and the like, and each antenna The phase rotation value to be applied to may be additionally included. In addition, according to an embodiment, feedback of a phase rotation value from the terminal 20 to the base station 10 may be performed in a frequency division multiplex (FDD) system.

The first feedback information may be a periodically transmitted sounding reference signal (SRS).

The processing unit 12 determines whether to increase or decrease the set transmission period by comparing the set transmission period with the calculated coherence time.

In this case, when the set transmission period is less than the calculated coherence time, the processing unit 12 increases the set transmission period in consideration of the calculated coherence time.

In addition, when the set transmission period is greater than the calculated coherence time, the processing unit 12 reduces the set transmission period in consideration of the calculated coherence time.

The second feedback information may be a PMI (Precoding Matrix Index) that is periodically transmitted.

The processing unit 12 determines whether to increase or decrease the set transmission period by comparing the set transmission period with the calculated coherence time.

In this case, when the set transmission period is less than the calculated coherence time, the processing unit 12 increases the set transmission period in consideration of the calculated coherence time.

In addition, when the set transmission period is greater than or equal to the calculated coherence time, the processing unit 12 reduces the set transmission period in consideration of the calculated coherence time.

On the other hand, the processing unit 12 aperiodically sets the transmission period of the channel feedback information when the identified number of terminals 20 is less than a set reference value.

In this case, the processing unit 12 receives the first feedback information when the measured strength of the uplink signal for each terminal 20 is greater than or equal to a set value. In addition, when the measured strength of the uplink signal for each terminal 20 is less than a set value, second feedback information is transmitted.

For the strength of the uplink signal for each terminal 20, refer to the above description.

The first feedback information may be a sounding reference signal (SRS) transmitted aperiodically.

The second feedback information may be a precoding matrix index (PMI) transmitted aperiodically.

According to the method for improving beamforming performance in a base station according to the present invention as described above and a control device for performing the same, the base station provides channel feedback information for beamforming based on the strength of the uplink signal of the terminal in a Sounding Reference Signal (SRS). Alternatively, by selecting and transmitting a PMI (Precoding Matrix Index), the base station can reduce the influence of the channel estimation error, thereby improving the beamforming performance.

In addition, by configuring the base station to select and transmit the transmission period of the channel feedback information in a periodic or aperiodic manner based on the number of terminals, unnecessary waste of resources due to transmission of channel feedback information can be prevented. have.

In addition, the base station is configured to reset the transmission period of the channel feedback information based on the mobile speed of the mobile station and the coherence time calculated based on this, or use the Doppler effect when there is no location information of the mobile station. By configuring the speed to be determined, it is possible to reduce an error due to a channel estimation error due to movement of the terminal.

In the above, even if all the constituent elements constituting the embodiments of the present invention have been described as being combined into one or operating in combination, the present invention is not necessarily limited to these embodiments. That is, within the scope of the object of the present invention, all of the constituent elements may be selectively combined and operated in one or more. In addition, terms such as "include", "consist of" or "have" described above mean that the corresponding component may be present unless otherwise stated, excluding other components. It should not be construed as being able to further include other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. Terms generally used, such as terms defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related technology, and are not interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments posted in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

10: base station 11: communication unit
12: processing unit
20: terminal

Claims (46)

In the method for improving beamforming performance in a base station for at least one terminal connected to a base station through a communication channel,
Identifying a communication environment for each terminal, and determining a transmission method of channel feedback information transmitted from the terminal to the base station for beamforming according to the determined communication environment for each terminal; And
Receiving the channel feedback information transmitted from the terminal according to the determined channel feedback information transmission method; Including,
Determining the channel feedback information transmission method,
Determining the number of terminals connected to the base station through a communication channel;
Setting a transmission period of channel feedback information transmitted from the terminal based on the identified number of terminals;
Measuring the strength of an uplink signal for each terminal based on the channel feedback information transmitted from the terminal; And
And setting channel feedback information to be transmitted from the terminal through the determined number of terminals and the measured strength of the uplink signal for each terminal. The method of claim 1,
The communication environment includes the number of terminals connected to the base station, an uplink signal strength of channel feedback information transmitted from the terminal to the base station, and a movement speed of the terminal, and the movement speed of the terminal is optionally included. Method for improving beamforming performance in a base station. delete The method of claim 1,
A method for improving beamforming performance in a base station, comprising periodically setting a transmission period of channel feedback information when the identified number of terminals is greater than or equal to a set reference value. The method of claim 4,
Estimating a movement speed for each terminal through the channel feedback information transmitted from the terminal; beamforming performance improvement method in a base station further comprising. The method of claim 5,
The movement speed for each terminal is calculated based on a Doppler shift for channel feedback information transmitted from the terminal. The method of claim 5,
The movement speed for each terminal is calculated based on the location location of the terminal through a movement distance of the terminal over time. The method of claim 5,
Calculating a coherence time for each terminal through the movement speed for each terminal; further comprising a method for improving beamforming performance in a base station. The method of claim 8,
When the measured strength of the uplink signal for each terminal is greater than or equal to a set value, first feedback information is transmitted,
When the measured strength of the uplink signal for each terminal is less than a set value, second feedback information is transmitted. The method of claim 9,
The strength of the uplink signal for each terminal is based on a signal received through a Sounding Reference Signal (SRS), a Physical Uplink Control Channel (PUCCH), and a Physical Uplink Shared Channel (PUSCH). A method of improving beamforming performance in a base station, characterized in that to determine by measuring (to Interference Noise Ratio). The method of claim 9,
The first feedback information is a method for improving beamforming performance in a base station, characterized in that the SRS (Sounding Reference Signal) is periodically transmitted. The method of claim 11,
Determining whether to increase or decrease the set transmission period by comparing the set transmission period with the calculated coherence time. The method of claim 12,
When the set transmission period is less than the calculated coherence time, increasing the set transmission period in consideration of the calculated coherence time. The method of claim 12,
When the set transmission period is greater than or equal to the calculated coherence time, reducing the set transmission period in consideration of the calculated coherence time. The method of claim 9,
The second feedback information is a method for improving beamforming performance in a base station, characterized in that the PMI (Precoding Matrix Index) is periodically transmitted. The method of claim 15,
Determining whether to increase or decrease the set transmission period by comparing the set transmission period with the calculated coherence time. The method of claim 16,
When the set transmission period is less than the calculated coherence time, the set transmission period is increased in consideration of the calculated coherence time. The method of claim 16,
When the set transmission period is greater than or equal to the calculated coherence time, the set transmission period is reduced in consideration of the calculated coherence time. The method of claim 1,
A method of improving beamforming performance in a base station, characterized in that when the number of the identified terminals is less than a set reference value, a transmission period of channel feedback information is aperiodically set. The method of claim 19,
When the measured strength of the uplink signal for each terminal is greater than or equal to a set value, first feedback information is transmitted,
When the measured strength of the uplink signal for each terminal is less than a set value, second feedback information is transmitted. The method of claim 20,
The strength of the uplink signal for each terminal is based on a signal received through a Sounding Reference Signal (SRS), a Physical Uplink Control Channel (PUCCH), and a Physical Uplink Shared Channel (PUSCH). A method of improving beamforming performance in a base station, characterized in that to determine by measuring (to Interference Noise Ratio). The method of claim 20,
The first feedback information is a method for improving beamforming performance in a base station, characterized in that the SRS (Sounding Reference Signal) transmitted aperiodically. The method of claim 20,
The second feedback information is a method of improving beamforming performance in a base station, characterized in that the aperiodically transmitted PMI (Precoding Matrix Index). In the control apparatus according to the method for improving beamforming performance in a base station according to claim 1,
A communication unit receiving channel feedback information from at least one terminal; And
A processing unit that determines a communication environment of a terminal that has transmitted the channel feedback information, selects a channel feedback information transmission method for beamforming, and receives channel feedback information according to the selected channel feedback information transmission method; and
In the processing unit,
Determine the number of terminals connected to the base station through a communication channel,
Set a transmission period of channel feedback information transmitted from the terminal through the identified number of terminals,
Measure the strength of the uplink signal for each terminal based on the channel feedback information transmitted from the terminal,
And setting channel feedback information to be transmitted from the terminal through the determined number of terminals and the measured strength of the uplink signal for each terminal. The method of claim 24,
The communication environment includes the number of terminals connected to the base station, an uplink signal strength of channel feedback information transmitted from the terminal to the base station, and a movement speed of the terminal, and the movement speed of the terminal is optionally included. controller. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

Images