KR20170049960A - Base station device and terminal, and signal processing method - Google Patents

Abstract

The present invention relates to a base station device, a terminal, and a signal processing method, in a wireless environment with a non-orthogonal multiple access (NOMA) scheme applied, capable of minimizing errors that occur in a process, which is called as successive interference cancelation (SIC), in which a terminal located close to a base station device cancels a signal of another terminal located relatively far from the base station device. The present invention comprises: a determination unit configured to determine the number of pilot signals, which are transmitted to a specific terminal of a terminal group, to be different from the number of pilot signals, which are transmitted to the other terminals of the terminal group; and a transmitter configured to transmit information related to the pilot signals set with the determined number to the other terminals so that the other terminals can measure a channel state associated with the specific terminal based on the pilot signals set with the determined number.

Description

TECHNICAL FIELD [0001] The present invention relates to a base station apparatus and a terminal, and a signal processing method,

The present invention relates to a wireless environment in which a non-orthogonal multiple access (NOMA) scheme is applied, a terminal located close to a base station apparatus removes a signal of another terminal located relatively far from the base station apparatus (SIC, Successive Interference Cancellation ) To minimize the errors that occur during the process.

Non-orthogonal multiple access (NOMA) using superposition coding of a base station apparatus and SIC (successive interference cancellation) of a terminal is currently being studied in a wide range.

In the case of orthogonal frequency division multiple access (OFDMA), when a base station apparatus transmits a signal to a plurality of terminals, frequency orthogonality between signals is maintained.

On the other hand, in the non-orthogonal multiple access scheme using superposition coding, when a base station transmits signals to a plurality of terminals, the signals are transmitted in a manner that signals are superimposed on each other on the frequency axis.

If the transmission is performed using only superposition coding, it is impossible to demodulate the signals by overlapping the signals of the plurality of terminals. Therefore, the base station transmits the signals with different power ratios allocated to the terminals.

At this time, in the non-orthogonal multiple access scheme, a power ratio is generally allocated to a terminal closer to a base station apparatus and a terminal located farther away. The reason why the power ratio is distributed differently is that a nearby terminal uses SIC The user's signal must be removed.

Here, the SIC refers to a process of demodulating a signal received from the base station apparatus by demodulating and removing the signal of the other terminal.

As described above, the SIC of the terminal located relatively close to the base station apparatus is based on the channel state measurement result related to the terminal which is relatively far away. If the channel state measurement result related to the far terminal is guaranteed, The probability of occurrence of an error in the SIC process performed in the terminal is increased.

Here, the high probability that an error occurs in the SIC process means that the signal of the other terminal can not be completely removed from the signal received from the base station apparatus.

If the signal of the other terminal can not be completely removed due to an error in the SIC process, the influence of the interference between the terminal signals to which the same radio resource is allocated becomes large, which degrades the data rate of each terminal .

As a result, in order to improve the data transmission rate in each terminal in a radio environment in which a non-orthogonal multiple access (NOMA) scheme is applied, a terminal located close to the base station apparatus is required to transmit data It is necessary to search for a method to minimize the error generated in the process of removing the signal.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a mobile station in a wireless environment in which a non-orthogonal multiple access (NOMA) And minimizes an error generated in the process of removing signals (SIC, Successive Interference Cancellation) of the other terminal located relatively far from the base station apparatus.

According to another aspect of the present invention, there is provided a base station apparatus for transmitting a pilot signal transmitted to a specific terminal in a terminal group to which a same radio resource is allocated in a cell, A determination unit that determines the number of signals different from the number of signals; And a transfer unit for transferring information related to the pilot signal determined to be the other number to the remaining terminal and allowing the remaining terminal to measure a channel state associated with the specific terminal based on the pilot signal determined to be the other number .

More specifically, the number of pilot signals transmitted to the specific terminal is determined to be greater than the number of pilot signals transmitted to the remaining terminals.

More specifically, when the number of pilot signals transmitted to the specific terminal is determined to be greater than the number of pilot signals transmitted to the remaining terminals, the accuracy of the channel state measurement result associated with the specific terminal is determined based on channel state measurement Which is higher than the accuracy of the result.

More specifically, the specific terminal is a terminal located farther from the base station than the remaining terminal, or is a terminal having a lower accuracy of the channel state measurement result than the remaining terminal.

More specifically, the accuracy of the channel state measurement result is lowered as the signal-to-noise ratio in the channel state information is lower.

According to another aspect of the present invention, there is provided a terminal for receiving information related to a pilot signal determined as a different number from a terminal in a terminal group to which a same radio resource is allocated in a cell from a base station apparatus ; A measuring unit for measuring a channel state associated with the specific terminal based on information related to the pilot signal determined as the other number; And a demultiplexer for demultiplexing a signal of the specific terminal received through the radio resource based on a channel state measurement result associated with the specific terminal.

More specifically, the number of pilot signals determined for the specific terminal is determined to be greater than the number of pilot signals determined for the remaining terminals in the terminal group.

More specifically, the specific terminal is a terminal located farther from the base station apparatus than the remaining terminals in the terminal group, or is a terminal having a lower accuracy of the channel state measurement result than the remaining terminals.

According to an aspect of the present invention, there is provided a signal processing method, wherein a base station apparatus transmits a pilot signal transmitted to a specific terminal in a terminal group to which the same radio resource is allocated in a cell, Determining a number of pilot signals different from the number of pilot signals transmitted to the terminal; And the base station apparatus transmits information related to the pilot signal determined to be the other number to the remaining terminal so that the remaining terminal can measure the channel state associated with the specific terminal based on the pilot signal determined to be the other number And a transfer step of transferring the image data.

More specifically, the number of pilot signals transmitted to the specific terminal is determined to be greater than the number of pilot signals transmitted to the remaining terminals.

According to another aspect of the present invention, there is provided a method for processing a signal, the method comprising the steps of: receiving information related to a pilot signal determined as a different number from a remaining number of terminals for a specific terminal in a terminal group to which the same radio resource is allocated in a cell; From a base station apparatus; A measuring step of measuring, by the terminal, a channel state associated with the specific terminal based on information related to the pilot signal determined by the other number; And a removal step of removing the signal of the specific terminal received through the radio resource based on a channel state measurement result related to the specific terminal.

More specifically, the number of pilot signals determined for the specific terminal is determined to be greater than the number of pilot signals determined for the remaining terminals in the terminal group.

Accordingly, in a base station apparatus, a terminal, and a signal processing method according to an embodiment of the present invention, in a wireless environment in which a non-orthogonal multiple access (NOMA) scheme is applied, (SIC) is minimized by minimizing errors generated in the process of SIC (Successive Interference Cancellation), the influence of interference between the UEs to which the same radio resource is allocated is reduced, Improvement can be expected.

1 is an exemplary diagram illustrating a wireless environment according to an embodiment of the present invention;
FIG. 2 is an exemplary diagram for explaining a transmission power ratio according to an embodiment of the present invention; FIG.
FIG. 3 is an exemplary diagram illustrating a resource allocation method according to an embodiment of the present invention; FIG.
4 is an exemplary diagram illustrating a bit error rate (BER) when a channel state measurement error occurs according to an embodiment of the present invention;
5 is a schematic configuration diagram of a base station apparatus according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating an example of a radio environment for explaining a base station apparatus according to an embodiment of the present invention. FIG.
FIG. 7 is an exemplary diagram showing an example of the number of pilot signals according to an embodiment of the present invention; FIG.
FIG. 8 is a schematic configuration diagram of a terminal according to an embodiment of the present invention; FIG.
FIG. 9 is a flowchart illustrating an operation flow in a base station apparatus according to an embodiment of the present invention; FIG.
10 is a flowchart illustrating an operation flow in a terminal according to an embodiment of the present invention;

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

1 illustrates a wireless environment according to an embodiment of the present invention.

1, a radio environment according to an embodiment of the present invention includes a base station apparatus 10 and a plurality of terminals 20 (UE0, UE1, UE2, UE3, ..., and UEN ) May be included.

The base station apparatus 10 includes a cell C and a base station for providing a mobile communication service to a plurality of terminals UE0, UE1, UE2, UE3, ..., and UEN located in the cell C For example, a NodeB and an eNodeB.

In the case of the terminal 20 (UE0, UE1, UE2, UE3, ..., and UEN), mobile or fixed user nodes such as UE (User Equipment) and MS (Mobile Station)

The radio environment according to an embodiment of the present invention may follow a non-orthogonal multiple access scheme such as a Non-Orthogonal Multiple Access (NOMA) technique for the purpose of increasing frequency capacity in a cell.

As described above, the non-orthogonal multiple access scheme uses a superposition coding function of the base station apparatus 10 to transmit signals to a plurality of terminals in a manner that signals overlap each other on the frequency axis .

When transmission is performed using only superposition coding, it is impossible to demodulate the signals by overlapping the signals of the plurality of terminals. Therefore, the base station apparatus 10 transmits the signals with different power ratios allocated to the terminals.

At this time, in general, the base station apparatus 10 allocates a low power ratio to terminals located closer to the distant terminal. The reason why the power ratio is distributed differently is that a nearby terminal uses SIC (Successive Interference Cancellation) Thereby removing the signal of the user located far away.

In this regard, FIG. 2 shows an example in which the base station apparatus 10 assigns a different transmission power ratio to each terminal.

Referring to FIG. 2, it can be seen that the transmission power ratio of the terminal UE1 closer to the base station apparatus 10 is allocated to the base station apparatus 10 than the UE2 which is a far-away terminal.

FIG. 3 shows a comparison between the transmission power in the orthogonal frequency division multiplexing access (OFDMA) scheme and the non-orthogonal multiple access technique and the resource allocation scheme in the frequency axis.

Referring to FIG. 3, in the application of the non-orthogonal multiple access scheme, the UE 1, which is a terminal located close to the base station apparatus 10, uses the SIC to demodulate the signal, While the UE 2 does not use the SIC.

In case of the UE 1, the signal of the UE 2 is demodulated before using the SIC, and this signal is removed from the original signal, leaving only the signal of the UE 1. If this process is performed, the interference is eliminated in the UE 1 and the signal to noise ratio ) Is improved.

On the other hand, since the UE 2 does not use the SIC, it attempts demodulation by using the signal transmitted from the base station apparatus 10 as a general signal demodulation situation without any processing. The reason why the UE 2 does not attempt SIC is that, (10) There is a reason for the allocated transmission power ratio.

That is, in order for the user to try SIC, the intensity of the interference signal should be higher than a certain threshold value because demodulating a strong signal is much easier and more realistic than demodulating a weak signal.

For example, the reason for the SIC of the UE 1 is that the base station device 10 has assigned a higher power ratio to the UE 2 located relatively farther from the UE 1, and when a signal sent from the base station device 10 in the UE 1 position reaches, SIC is possible because the strength is stronger than the strength of the UE1 signal.

On the other hand, in order for the UE 2 to perform the SIC, the strength of the signal of the UE 1 should be stronger than that of the UE 2, but since the strength of the UE 2 is greater than the strength of the signal of the UE 1, the SIC can not be performed. will be.

Meanwhile, although studies on non-orthogonal multiple access schemes are currently under way, most researches are proceeding without considering channel state measurement errors and SIC errors.

However, these two errors can be considered to be very important in the non-orthogonal multiple access scheme. In particular, since the channel state measurement error may lead to a SIC error with respect to the SIC terminal, There is a need for measures to reduce errors in measurement state measurement.

In this paper, several studies have been carried out to derive the performance evaluation results considering the channel state measurement error and the SIC error in the terminal, but there is no study on how to reduce the two errors.

In this regard, in the UE1 and the UE2, channel state measurement is performed based on the pilot signal received from the base station apparatus 10. The SIC process performed in the UE 1 using the channel state measurement result will be described in more detail .

For convenience of explanation, the error of the channel state measurement is defined as [Equation 1] below.

[Equation 1]

는 사용자가 측정한 채널, e는 0~1사이의 값을 갖는 요소로 채널 측정의 정확성을 나타낸다. e가 0이라면 완벽한 채널 측정(Perfect Channel Estimation)이고 e가 1이 라면 채널 측정이 사실상 무의미한 경우라고 할 수 있다. Ω는 CN~(0,1)의 분포를 지닌 복소 가우시안 랜덤 변수이다.here,

Is the channel measured by the user, and e is an element having a value between 0 and 1, indicating the accuracy of the channel measurement. If e is 0, it is Perfect Channel Estimation. If e is 1, channel measurement is actually meaningless. Ω is a complex Gaussian random variable with a distribution of CN ~ (0, 1).

For reference, it is assumed that the expression is developed by applying the Taylor expansion, for example, using the equation e << 1 described below.

A signal received from the base station apparatus 10 can be expressed as in the following [Equation 2].

[Equation 2]

Here, H1 is a channel state, X1 is a signal of UE1, X2 is a signal of UE2, and N1 is noise.

(

)을 곱함으로써 UE2의 신호 검출을 시도하게 되며, 이는 아래 [수식 3]과 같이 표현될 수 있다.Assuming that there is no error in the measurement of the channel state, UE1 recognizes the channel state accurately. Therefore, since the base station channel is perfectly known,

(

), Thereby attempting to detect the signal of the UE 2, which can be expressed as in Equation (3) below.

[Equation 3]

In this regard, the UE 1 demodulates the signal of the UE 2 through hard decision, for example, and attempts to remove the signal of the UE 2, which can be expressed as [Equation 4].

[Equation 4]

At this time, it is assumed that the transmission power of the UE 2 is larger than the transmission power of the UE 1, so that it is possible to detect the signal of the correct UE 2.

If it is assumed that there is no error in the channel state measurement, it is possible to demodulate the signal of the UE 2 relatively easily and to perform the SIC, thereby improving the data transmission rate in the UE 1 and the UE 2.

On the other hand, when it is assumed that there is an error in the channel state measurement, the process of SIC in the UE 1 is as follows.

The signal received from the base station apparatus 10 can be expressed as in Equation 5 as in the case where there is no error in the channel state measurement.

[Equation 5]

라고 가정하고, 예컨대, ZF detection을 이용하여 SIC가 수행되는 경우라면, 기지국장치(10)로부터 수신된 신호는 아래 [수식 6]과 같이 표현하는 것이 가능하다(

).The channel state measurement result when there is an error in the channel state measurement

And the SIC is performed using, for example, ZF detection, the signal received from the base station apparatus 10 can be expressed as in Equation (6) below

).

[Equation 6]

In this regard, the UE 1 demodulates the signal of the UE 2 through hard decision, for example, and attempts to remove the signal of the UE 2, which can be expressed as [Equation 7].

[Equation 7]

이므로, 채널상태 측정에 오류가 없을 때와 비교하여 UE2와 UE1의 신호 이외의 간섭이 발생하는 것을 수식으로서 확인할 수 있다.here,

It is possible to confirm as an equation that interference other than the signals of the UE2 and the UE1 occurs as compared with the case where there is no error in the channel state measurement.

가 아닌

를 얻게 되는 데, 이러한

은 복조 오류로 인해 잘못 검출된 UE2의 신호를 나타낸다.Therefore, the signal of UE2 with a very high probability [Expression 6]

Not

.

Indicates a signal of UE2 that is erroneously detected due to a demodulation error.

Referring to Equation (7), it can be seen that the UE 1 does not perform a proper SIC because it uses the signal of the UE 2 which is not detected as well as the SIC using the channel state measurement result.

)과 self-interference(

)가 발생하여 극심한 성능 저하를 보일 수 있게 되는 것이다.This is because merely a channel state measurement error is added, but in UE1 residual interference (

) And self-interference (

) Is generated, and it is possible to show severe performance degradation.

In other words, since the non-orthogonal multiple access scheme uses superposition coding at the base station, it is better to use the orthogonal multiple access technique than to use a method that can reduce the channel state measurement error used in the conventional frequency division orthogonal multiple access It is necessary to prepare appropriate measures.

In this regard, FIG. 4 shows an example related to a change in BER (Bit Error Rate) when a channel state measurement error occurs.

Referring to FIG. 4, it can be clearly seen that the performance decreases as the error increases in the channel state measurement.

As a result, it is expected that it is possible to lower the BER by reducing the channel state measurement error in the terminal performing the SIC and consequently to improve the data transmission rate at the terminal. Also, in the case of the terminal not performing the SIC, It can be expected that the BER can be improved.

Accordingly, in an embodiment of the present invention, a method for minimizing an error generated in the SIC process by raising the accuracy of a channel state measurement result in a terminal is proposed. Hereinafter, a base station apparatus 10, (20) will be described in detail.

First, the configuration of a base station apparatus 10 according to an embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a schematic diagram showing a configuration in a base station apparatus 10 according to an embodiment of the present invention.

5, the base station apparatus 10 according to an embodiment of the present invention includes a determination unit 11 for determining the number of pilot signals to be transmitted to the terminal 20, and information related to the number of pilot signals And a transfer unit 12 for transferring the data to the terminal 20.

The entire configuration or at least a part of the base station apparatus 10 including the determination unit 11 and the transmission unit 12 described above may be implemented in the form of a software module or a hardware module or a combination of a software module and a hardware module .

As a result, the base station apparatus 10 according to an embodiment of the present invention can increase the accuracy of the channel state measurement result in the terminal 20 through the above configurations, thereby minimizing errors generated in the SIC process. Hereinafter, each configuration in the base station apparatus 10 for implementing the present invention will be described in more detail.

For convenience of explanation, it is assumed that UE1 and UE2 exist as a UE 20 to which the same radio resource is allocated according to a non-orthogonal multiple access scheme as shown in FIG.

Here, it is assumed that UE1 is a terminal located closer to the base station 10 than the UE2 and is a terminal that performs SIC and is located relatively far away from the UE2 base station 10 and does not perform SIC.

The determining unit 11 determines the number of pilot signals transmitted to each terminal 20 in the cell.

More specifically, the determining unit 11 determines the number of pilot signals to be transmitted to each of UE1 and UE2 to which the same radio resource is allocated in the cell.

At this time, the determination unit 11 determines a larger number of pilot signals to be transmitted to the UE 2, which is a terminal in which the SIC is not performed, than the number of pilot signals to be transmitted to the UE 1, which is the terminal on which the SIC is performed.

FIG. 7 shows an example of the number of pilot signals (density of pilot signal) determined for UE1, which is a terminal on which SIC is performed, and UE2, on which SIC is performed.

Referring to FIG. 7A, it can be seen that the same number of pilot signals are determined for UE1, which is a terminal performing SIC and UE2, where SIC is performed, according to the existing method.

In contrast, referring to FIG. 7B, it can be seen that the number of pilot signals to be transmitted to the UE 2 in which SIC is not performed is determined to be larger than that of the UE 1 in which the SIC is performed according to an embodiment of the present invention.

This can be done by way of increasing the number of subcarriers carried by the pilot signal in the same frequency band.

The determination of the number of pilot signals for the UE 2 in which the SIC is not performed more than the UE 1 in which the SIC is performed is determined by measuring the channel state at the UE 2 in which the SIC is not performed, This is to increase the accuracy of the results.

That is, the UE 1 and the UE 2 measure a channel state with respect to a subcarrier on which a pilot signal is received. For example, a channel state for a subcarrier on which a pilot signal is not transmitted is estimated through interpolation using a correlation between subcarriers .

As a result, in UE1 and UE2, as the number of pilot signals received from base station apparatus 10 increases, the number of subcarriers for which actual channel state measurement is performed is not an estimation of channel state within the same frequency band. Can lead to an effect of improving the accuracy (reducing errors in the channel state measurement result).

In this case, when a pilot signal is received from the base station apparatus 10, the UE 1 and the UE 2 measure a channel state associated with a subcarrier band in which the pilot signal is received, and measure the channel state measurement result as channel state information, 10).

The transmitter 12 performs a function of transmitting information related to the pilot signal.

More specifically, when a different number of pilot signals for UE1 and UE2 are determined, the transmitter 12 transmits information related to the pilot signal determined for UE2, which is a terminal for which no SIC is performed, To the UE1.

The transmitting of the information related to the pilot signal determined for the UE 2 to the UE 1 in which the SIC is performed is performed by using the channel state measurement result related to the UE 2 in the SIC performing process in the UE 1, Demodulation and elimination are performed on the signal of FIG.

In this regard, UE1, which is a terminal on which SIC is performed, measures a channel state associated with UE2, which is a terminal in which SIC is not performed, using information related to the pilot signal of UE2 received from base station apparatus 100, Demodulate and remove the signal of the UE 2 from the signal received from the base station apparatus 10 by using the demodulation and demodulation of the signal of the UE 2.

At this time, it is presupposed that the probability of error occurrence in the channel state measurement result is minimized due to the increase in the number of pilot signals determined for UE2, and therefore, UE1, which performs SIC using the channel state measurement result, It can be expected that the signal of the UE 2 can be completely demodulated and removed from the signal received from the base station apparatus 10 as described with reference to Equations (1) to (4).

The configuration of the base station apparatus 10 according to an embodiment of the present invention will be described below with reference to FIG. 8, and the configuration of the terminal 20 according to an embodiment of the present invention will be described.

FIG. 8 is a schematic diagram showing a configuration in a terminal 20 according to an embodiment of the present invention.

Here, it is assumed that the configuration of the terminal 20 shown in FIG. 8 is the configuration of the UE 1, which is the terminal on which the SIC is performed in the preceding example with reference to FIG.

8, a terminal 20 according to an embodiment of the present invention includes a receiving unit 21 for receiving information related to a pilot signal determined for a UE 2, which is a terminal in which SIC is not performed, from a base station apparatus 10, A measurement unit 22 for measuring the channel condition associated with the UE 2, and a removal unit 23 for removing the signal of the UE 2 received via the radio resource.

The entire configuration or at least a part of the terminal 20 including the receiving unit 21, the measuring unit 22 and the removing unit 23 may be implemented in the form of a software module or a hardware module, . &Lt; / RTI &gt;

As a result, the terminal 20 according to the embodiment of the present invention can minimize the error generated in the SIC process through the above configurations. Hereinafter, each configuration in the terminal 20 for realizing the error can be more concretely described I will explain.

The receiving unit 21 performs a function of receiving information related to the pilot signal.

More specifically, the receiving unit 21 receives information related to the pilot signal determined for the UE 2, which is a terminal to which the SIC is not performed among the terminals to which the same radio resource is allocated, from the base station apparatus 10.

In this regard, in order to increase the accuracy of the channel state measurement result in the UE 2 in which the SIC is not performed, the base station apparatus 10 may increase the number of pilot signals for the UE 2 in which the SIC is not performed, .

The measurement unit 22 performs a function of measuring a channel state.

More specifically, the measurement unit 22 measures the channel state associated with the UE 2 using information related to the pilot signal determined for the UE 2.

At this time, the measuring unit 22 measures a channel state of a subcarrier on which the pilot signal determined for the UE 2 is carried. For the subcarrier for which the pilot signal is not received, for example, interpolation using a correlation between subcarriers, Lt; RTI ID = 0.0 &gt; state. &Lt; / RTI &gt;

Here, in the case of the number of pilot signals determined for UE2, since the number of pilot signals determined for UE2 is determined to be larger than that of UE1 in which SIC is not performed, it can be seen that the number of subcarriers carrying pilot signals increases accordingly.

As a result, in the measurement result of the channel state measured in relation to the UE 2 in the measurement unit 22, since it corresponds to a result substantially measured for a large number of subcarriers as many as the number of pilot signals of the UE 2, It can be expected that the probability becomes low.

The removal unit 23 performs a function of removing the signal of the UE2.

More specifically, the demultiplexer 23 demodulates and removes the signal of the UE 2 from the signal received from the base station apparatus 10 using the channel state measurement progress when the measurement of the channel state associated with the UE 2 is completed, It is possible to demodulate its own signal received from the base station.

Here, since it is assumed that the error occurrence probability in the channel state measurement result is minimized due to the increase in the number of pilot signals determined for UE2, the channel state measurement result measured with respect to UE2 is expressed by Equation (1) It can be expected that the signal of the UE 2 can be completely demodulated and removed from the signal received from the base station apparatus 10 as described above.

As described above, according to the base station apparatus 10 and the terminal 20 according to an embodiment of the present invention, in a wireless environment in which a non-orthogonal multiple access (NOMA) scheme is applied, It is possible to minimize the error generated in the process of removing the signal of the other terminal located far away from the base station apparatus (SIC), thereby reducing the influence of interference between the terminals to which the same radio resource is allocated, It is expected that the data transmission rate (throughput) can be improved.

Meanwhile, in the above description, error occurrence in the channel state measurement result in the terminal located relatively far from the base station apparatus 10 is prevented by non-uniformly allocating the pilot signal for transmission to each terminal, A method of suppressing the occurrence of errors in the channel state measurement result by increasing the transmission power for a terminal located relatively far from the base station apparatus 10 is also possible.

However, when the transmission power for a terminal located relatively far away from the base station apparatus 10 is increased to suppress an error in the channel state measurement result, a white noise (e.g., Addictive White Gaussian Noise) increase phenomenon Further consideration should be given.

9 and 10, the operation flow in each of the base station apparatus 10 and the terminal 20 is described below with reference to the configuration of the base station apparatus 10 and the terminal 20 according to the embodiment of the present invention, Will be described.

First, the operation flow in the base station apparatus 10 according to an embodiment of the present invention will be described with reference to FIG.

FIG. 9 is a flowchart illustrating an operation flow in the base station apparatus 10 according to an embodiment of the present invention.

First, the determination unit 11 determines the number of pilot signals to be transmitted to UE1 and UE2 to which the same radio resource is allocated in the cell according to step 'S11'.

At this time, the determination unit 11 determines a larger number of pilot signals to be transmitted to the UE 2, which is a terminal in which the SIC is not performed, than the number of pilot signals to be transmitted to the UE 1, which is the terminal on which the SIC is performed.

FIG. 7 shows an example of the number of pilot signals (density of pilot signal) determined for UE1, which is a terminal on which SIC is performed, and UE2, on which SIC is performed.

Referring to FIG. 7A, it can be seen that the same number of pilot signals are determined for UE1, which is a terminal performing SIC and UE2, where SIC is performed, according to the existing method.

In contrast, referring to FIG. 7B, it can be seen that the number of pilot signals to be transmitted to the UE 2 in which SIC is not performed is determined to be larger than that of the UE 1 in which the SIC is performed according to an embodiment of the present invention.

This can be done by way of increasing the number of subcarriers carried by the pilot signal in the same frequency band.

The determination of the number of pilot signals for the UE 2 in which the SIC is not performed more than the UE 1 in which the SIC is performed is determined by measuring the channel state at the UE 2 in which the SIC is not performed, This is to increase the accuracy of the results.

That is, the UE 1 and the UE 2 measure a channel state with respect to a subcarrier on which a pilot signal is received. For example, a channel state for a subcarrier on which a pilot signal is not transmitted is estimated through interpolation using a correlation between subcarriers .

As a result, in UE1 and UE2, as the number of pilot signals received from base station apparatus 10 increases, the number of subcarriers for which actual channel state measurement is performed is not an estimation of channel state within the same frequency band. Can lead to an effect of improving the accuracy (reducing errors in the channel state measurement result).

In this case, when a pilot signal is received from the base station apparatus 10, the UE 1 and the UE 2 measure a channel state associated with a subcarrier band in which the pilot signal is received, and measure the channel state measurement result as channel state information, 10).

Then, when a different number of pilot signals for UE1 and UE2 are determined, the transmitter 12 transmits information related to the pilot signal determined for UE2, which is a terminal in which SIC is not performed, according to step 'S12' To UE1, which is a terminal to be performed.

In this regard, UE1, which is a terminal on which SIC is performed, measures a channel state associated with UE2, which is a terminal in which SIC is not performed, using information related to the pilot signal of UE2 received from base station apparatus 100, Demodulate and remove the signal of the UE 2 from the signal received from the base station apparatus 10 by using the demodulation and demodulation of the signal of the UE 2.

At this time, it is presupposed that the probability of error occurrence in the channel state measurement result is minimized due to the increase in the number of pilot signals determined for UE2, and therefore, UE1, which performs SIC using the channel state measurement result, It can be expected that the signal of the UE 2 can be completely demodulated and removed from the signal received from the base station apparatus 10 as described with reference to Equations (1) to (4).

10 is a flowchart for explaining an operation flow in the terminal 20 according to an embodiment of the present invention.

First, the receiving unit 21 receives information related to the pilot signal determined for the UE 2, which is a terminal to which the SIC is not performed among the terminals to which the same radio resource is allocated, from the base station apparatus 10 according to step 'S21'.

In this regard, in order to increase the accuracy of the channel state measurement result in the UE 2 in which the SIC is not performed, the base station apparatus 10 may increase the number of pilot signals for the UE 2 in which the SIC is not performed, .

Then, the measuring unit 22 measures channel conditions associated with the UE 2 using the information related to the pilot signal determined for the UE 2 according to step S22.

At this time, the measuring unit 22 measures a channel state of a subcarrier on which the pilot signal determined for the UE 2 is carried. For the subcarrier for which the pilot signal is not received, for example, interpolation using a correlation between subcarriers, Lt; RTI ID = 0.0 &gt; state. &Lt; / RTI &gt;

Here, in the case of the number of pilot signals determined for UE2, since the number of pilot signals determined for UE2 is determined to be larger than that of UE1 in which SIC is not performed, it can be seen that the number of subcarriers carrying pilot signals increases accordingly.

As a result, in the measurement result of the channel state measured in relation to the UE 2 in the measurement unit 22, since it corresponds to a result substantially measured for a large number of subcarriers as many as the number of pilot signals of the UE 2, It can be expected that the probability becomes low.

Thereafter, the demultiplexer 23 demodulates and removes the signal of the UE 2 from the signal received from the base station apparatus 10 using the channel state measurement progress when the channel state measurement associated with the UE 2 is completed according to step 'S23' It is possible to demodulate its own signal received from the base station apparatus 10. [

Here, since it is assumed that the error occurrence probability in the channel state measurement result is minimized due to the increase in the number of pilot signals determined for UE2, the channel state measurement result measured with respect to UE2 is expressed by Equation (1) It can be expected that the signal of the UE 2 can be completely demodulated and removed from the signal received from the base station apparatus 10 as described above.

As described above, according to the operation flow of the base station apparatus 10 and the terminal 20 according to the embodiment of the present invention, in a wireless environment in which a non-orthogonal multiple access (NOMA) , It is possible to minimize the error generated in the process of removing the signal of the terminal located close to the base station device and the signal of the other terminal located relatively far away from the base station device (SIC) The throughput of each terminal can be expected to be improved.

Meanwhile, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, or may be embodied in a computer readable medium, in the form of a program instruction, which may be carried out through various computer means. 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 configured for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

According to the base station apparatus, the terminal, and the signal processing method according to the present invention, when a non-orthogonal multiple access (NOMA) scheme is applied, each terminal It is possible to allocate a different amount of radio resources to each mobile station in consideration of the difference in data transmission rate between the mobile station and the mobile station, This is an invention that is industrially applicable because it is not only possible but also practically possible to carry out clearly.

10: base station device
11: Decision section 12:
20: terminal
21: receiving section 22: measuring section
23: Rejection

Claims (12)

A determination unit configured to determine a number of pilot signals transmitted to a specific terminal in a terminal group to which the same radio resource is allocated in a cell to be different from a number of pilot signals transmitted to the remaining terminals in the terminal group; And
And transmitting the information related to the pilot signal determined as the other number to the remaining terminal so that the remaining terminal can measure the channel state associated with the specific terminal based on the pilot signal determined to be the other number The base station apparatus comprising: The method according to claim 1,
The number of pilot signals transmitted to the specific terminal may be determined based on
Wherein the number of pilot signals is determined to be greater than the number of pilot signals transmitted to the remaining terminals. The method according to claim 1,
When the number of pilot signals transmitted to the specific terminal is determined to be greater than the number of pilot signals transmitted to the remaining terminals, the accuracy of the channel state measurement result associated with the specific terminal is less than the accuracy of the channel state measurement results associated with the remaining terminals The base station apparatus comprising: The method according to claim 1,
The specific terminal,
Wherein the terminal is located farther from the base station than the remaining terminal or the terminal is less accurate than the remaining terminal. 5. The method of claim 4,
The accuracy of the channel state measurement result may be determined,
And the signal-to-noise ratio in the channel state information decreases. A receiving unit for receiving, from a base station apparatus, information related to a pilot signal determined for a specific terminal in a terminal group to which a same radio resource is allocated in a cell, the pilot signal being determined to be different from the remaining terminals;
A measuring unit for measuring a channel state associated with the specific terminal based on information related to the pilot signal determined as the other number; And
And a demultiplexer for demultiplexing a signal of the specific terminal received through the radio resource based on a channel state measurement result associated with the specific terminal. The method according to claim 6,
Wherein the number of pilot signals determined for the specific terminal is:
Wherein the number of pilot signals is determined to be greater than the number of pilot signals determined for the remaining terminals in the terminal group. The method according to claim 6,
The specific terminal,
The terminal being located farther from the base station apparatus than the remaining terminal in the terminal group or being a terminal having a lower accuracy of the channel state measurement result than the remaining terminal. Determining a number of pilot signals transmitted to a specific terminal in a group of terminals to which the same radio resource is allocated in a cell differently from a number of pilot signals transmitted to the remaining terminals in the terminal group; And
The base station apparatus transmits information related to the pilot signal determined to be the other number to the remaining terminal so that the remaining terminal can measure the channel state associated with the specific terminal based on the pilot signal determined to be the other number And a transmitting step. 10. The method of claim 9,
The number of pilot signals transmitted to the specific terminal may be determined based on
Wherein the number of pilot signals is determined to be greater than the number of pilot signals transmitted to the remaining terminals. A receiving step of receiving, from a base station apparatus, information related to a pilot signal determined for a specific terminal in a terminal group to which the same radio resource is allocated in the cell, the pilot signal being different from the remaining terminals;
A measuring step of measuring, by the terminal, a channel state associated with the specific terminal based on information related to the pilot signal determined by the other number; And
And removing the signal of the specific terminal received through the radio resource based on a channel state measurement result associated with the specific terminal. 12. The method of claim 11,
Wherein the number of pilot signals determined for the specific terminal is:
Wherein the number of pilot signals is determined to be larger than the number of pilot signals determined for the remaining terminals in the terminal group.

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