KR101944506B1 - Method for detecting uplink signal in base station - Google Patents

Abstract

The present invention relates to a method for detecting an uplink signal in a base station. The method for detecting an uplink signal in a base station includes: a step of estimating a first index of a short-distance transmission antenna corresponding to a short-distance user terminal by performing MRRC about a whole received signal received from multiple user terminals to a base station; a step of detecting a short-distance uplink signal in a method of estimating a first symbol corresponding to the short-distance uplink signal using the first index; a step of removing the short-distance uplink signal in the whole received signal by performing SIC using the short-distance uplink signal; a step of estimating a second index of a long-distance transmitting antenna corresponding to the long-distance user terminal by performing MLE about a residual signal in which the short-distance uplink signal is removed; and a step of detecting the long-distance uplink signal by a method of estimating the second symbol corresponding to the long-distance uplink signal by using the second index. The method for detecting an uplink signal in a base station can effectively detect the uplink signal transmitted from the multiple user terminals from the base station by using spatial modulation (SM) and non-orthogonal multiple access (NOMA).

Description

TECHNICAL FIELD [0001] The present invention relates to a method for detecting an uplink signal in a base station,

The present invention relates to a method and apparatus for efficiently detecting an uplink signal transmitted from a plurality of user terminals using a spatial modulation (SM) and a non-orthogonal multiple access (NOMA) To a link signal detection method.

As is well known, mobile communication systems have been developed to provide voice services while ensuring the user's activity. However, the mobile communication system has expanded to the area of not only voice but also data service. At present, due to an increase of explosive traffic, there is a shortage of resources and users demand a higher speed service and a more advanced mobile communication system is required .

The requirements of this next-generation mobile communication system are largely due to the explosion of data traffic acceptance, a dramatic increase in the per-user data rate, a significant increase in the number of connected devices, very low end-to-end latency, It should be able to support.

For this purpose, a dual connectivity, a massive multiple input multiple output (MIMO), an in-band full duplex, a non-orthogonal multiple access (NOMA), a super wide- Support, and device networking. A variety of technologies such as device networking are being studied, and techniques for satisfying data rate and spectral efficiency are continuously being researched and developed.

1. Korean Patent Publication No. 10-2017-0023953 (published on Mar. 06, 2017)

An aspect of the present invention is to provide a method for detecting an uplink signal in a base station in which a base station can effectively detect an uplink signal transmitted from a plurality of user terminals using spatial modulation (SM) and non-orthogonal multiple access (NOMA).

In addition, the present invention performs MRRC (Maximum Receive Ratio Combining, hereinafter referred to as MRRC) on all received signals received from a plurality of user terminals to a base station, And estimates a first symbol corresponding to the nearest uplink signal using the estimated first index, thereby estimating a first symbol corresponding to the nearest uplink signal transmitted from the near- And to provide a link signal detection method.

In addition, it performs SIC (Successive Interference Cancellation, hereinafter referred to as 'SIC') using a local uplink signal detected from the entire received signal, removes a near-field uplink signal, and outputs a residual likelihood Estimates a second index of a long-distance transmission antenna corresponding to a remote user terminal by performing estimation and maximum likelihood estimation (hereinafter, referred to as 'MLE'), and estimates a second index corresponding to a second uplink signal corresponding to the far- A method for detecting an uplink signal in a base station capable of effectively detecting a long distance uplink signal transmitted from a remote user terminal by estimating a symbol.

The objects of the embodiments of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description .

According to an embodiment of the present invention, a method is provided for performing maximum receive ratio combining (MRRC) on an entire received signal received from a plurality of user terminals to estimate a first index of a local transmission antenna corresponding to a local user terminal , Detecting the nearest uplink signal by estimating a first symbol corresponding to the nearest uplink signal using the first index, and performing successive interference cancellation (SIC) using the nearest uplink signal And performing a maximum likelihood estimation (MLE) on the residual signal from which the near-field uplink signal has been removed, thereby obtaining a second index of a far-field transmission antenna corresponding to the far- Estimating a second upward index, using the second index, In a way of estimating the second symbol corresponding to a signal it can be provided with a UL signal detection method in a base station, comprising the step of detecting the distance up-link signal.

The present invention can effectively detect an uplink signal transmitted from a plurality of user terminals at a base station using spatial modulation (SM) and non-orthogonal multiple access (NOMA).

The present invention estimates a first index of a short-distance transmission antenna corresponding to a near-end user terminal by performing MRRC on all reception signals received from a plurality of user terminals at a base station, By estimating the first symbol corresponding to the link signal, the local uplink signal transmitted from the local user terminal can be effectively detected.

In addition, the SIC using the local uplink signal detected from the entire received signal is performed to remove the local uplink signal, and the MLE is performed on the residual signal to estimate the second index of the remote transmission antenna corresponding to the remote user terminal And estimating the second symbol corresponding to the far uplink signal using the estimated second index, thereby effectively detecting the far uplink signal transmitted from the far user terminal.

FIG. 1 is a flowchart illustrating a process of detecting an uplink signal transmitted from a plurality of user terminals in a base station according to an embodiment of the present invention.
2 is a diagram for explaining a NOMA system model applied to a method of detecting an uplink signal in a base station according to an embodiment of the present invention,
3 is a diagram for explaining an uplink signal detection system model in a base station according to an embodiment of the present invention,
4 to 8 are diagrams for explaining simulation results of a method of detecting an uplink signal in a base station according to an embodiment of the present invention.

Advantages and features of embodiments of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

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

FIG. 1 is a flowchart illustrating a process of detecting an uplink signal transmitted from a plurality of user terminals in a base station according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a method of detecting an uplink signal in a base station FIG. 3 is a view for explaining a model of an uplink signal detection system in a base station according to an embodiment of the present invention. Referring to FIG.

Referring to FIGS. 1 to 3, a first index of a short-distance transmission antenna corresponding to a near-end user terminal can be estimated by performing MRRC on a total reception signal received from a plurality of user terminals at a base station (step 110).

Then, the near-field uplink signal may be detected by estimating the first symbol corresponding to the near-field uplink signal using the first index (step 120).

Next, the SIC using the short distance uplink signal is performed to remove the short distance uplink signal from the entire received signal (step 130).

Then, MLE may be performed on the residual signal from which the near-field uplink signal is removed to estimate the second index of the far-field transmission antenna corresponding to the far-field user terminal (step 140).

Then, the remote uplink signal may be detected by estimating a second symbol corresponding to the far uplink signal using the second index (step 150).

2, in the uplink NOMA system model, a different power is transmitted to each UE (User Equipment, Quot; UE "), for example, a fixed user power allocation may be applied.

If it is assumed that a signal of a far-end user terminal (FEU) can be received at a base station (BS), a maximum transmission power can be applied to a near-end user terminal (NEU) The transmission power to the terminal FEU can be adjusted to a low level.

In the uplink NOMA system model as shown in FIG. 2, the transmitted signal can be expressed as Equation (1).

Where P _i denotes the i th user transmit power and s denotes the UE modulated symbol vector.

Then, by assuming perfect time and frequency synchronization for UE-i (i = 1, 2) at the base station (BS), the total received signal can be expressed as Equation (2).

Herein, h ₁ and h ₂ denote a complex channel impulse response matrix for UE-1 and UE-2, respectively, and n to CN (0, σ ² ) denote a complex band Gaussian noise (AWGN) Quot;).

Then, | h ₁ | ² > | h ₂ | ² , it can be clearly seen that UE-1 is a local user terminal (NEU) and UE-2 is a remote user terminal (FEU).

Also, the signal of the local user terminal (NEU) at the base station (BS) can be estimated before the signal of the remote user terminal (FEU) considering the signal of the remote user terminal (FEU) as noise, Lt; RTI ID = 0.0 > (NEU). ≪ / RTI > Here, in the case of the uplink NOMA system model, the SIC can be performed directly using the symbol of the detected near-end user terminal (NEU).

이 근거리 사용자 단말(NEU)의 검출된 심볼임을 정의함으로써, SIC의 나머지 결과는 다음의 수학식 3과 같이 표현될 수 있다.If a base station (BS) assumes a perfect channel

By defining that this is the detected symbol of the local user terminal (NEU), the remaining result of the SIC can be expressed as: < EMI ID = 3.0 >

On the other hand, in a spatial modulation (SM) system model, a third dimension called spatial dimension can be extended. Space modulation (SM) can provide low complexity and high spectral efficiency, and a transmit antenna index uses only one transmit antenna , And the total transmission bit per carrier wave (bpcu) can be expressed as Equation (4).

Where N _t means the number of transmitter antennas, M means the number of all possible modulated symbols, M for Quadrature Phase Shift Keying (QPSK) is 4, M for 8PSK Is 8.

로 나타낼 수 있다. 이어서, N_r이 수신 안테나의 수인 경우, 심볼 x₁은 다음의 수학식 5와 같은 MIMO(Multiple Input Multiple Output) 채널 H를 통해 송신된다:And, if it is assumed that q (k) is a vector including a m-bit to be sent, q (k) = can be expressed by _{[q 1 q 2 ... q m} ], the binary vector q (k) are N _t (K) of another vector x (k), and can be an element of a vector different from zero. Accordingly, the ₁ < _st > symbol of the vector x (k) is _xl , and l is the number of mapped transmission antennas

. Then, if N _r is the number of receive antennas, the symbol x ₁ is transmitted over a Multiple Input Multiple Output (MIMO) channel H as follows:

Here, h _{v and τ} denote the composite channel impulse response between the size of the receiving antenna v of N _r and the size of the transmitting antenna τ, and the size of the channel matrix H means N _r ㅧ N _t .

Finally, when w (k) is defined as AWGN, the reception vector can be expressed by the following Equation (6).

On the other hand, the receiver side can estimate the transmission antenna index and the transmission symbol of the UE. The transmission antenna index and the transmission symbol of the UE can be estimated using MRRC and MLE.

In the case of MRRC, the hidden covariance of the channel matrix H assumed to be known at the receiver and the received vector y (k) can be multiplied as shown in Equation (7).

Assuming perfect time and frequency synchronization, g (k) is equal to x (k), and if w (k) exists, the estimated antenna index number 1 can be calculated as Equation (8) .

Here, g _j (k) means the j-th element of the vector g (k).

Next, assuming that the antenna index can be accurately estimated, the transmitted symbol may be estimated as: < EMI ID = 9.0 >

는 열 벡터 g(k)에서 원소 번호

를 의미하고, Q[.]는 성상도 양자화(슬라이싱) 함수(constellation quantization (slicing) function)를 의미한다.From here,

(K) is an element number

, And Q [.] Denotes a constellation quantization (slicing) function.

On the other hand, another estimation technique, MLE, can be expressed as Equation (10).

에 대해 x(k)는 각각 추정된 안테나 인덱스 및 추정된 심볼을 의미하고, x_s는 가능한 전체 전송된 심볼을 포함하는 벡터를 의미한다.Here, j = 1, ..., N _t , s = 1, ..., M,

X (k) denotes an estimated antenna index and an estimated symbol, respectively, and x _s denotes a vector including the entire transmitted symbols.

The uplink SM NOMA system model combining the uplink NOMA system model and the SM system model as described above will be described. The vector q _n (t) for UE _n (n = 1, 2) vector, containing the m-bit transmission in both the _{UE-2, q n (t} ) is the Nt _n again maps to a different vector x _n (k) size, 0 and only one other vector x _n (k) Element.

The symbol numbers p and q of the vector x _n (k) are x _p and x _q , respectively, and p and q are mapped to the transmission antenna numbers p ∈ [1: Nt ₁ ] and q ∈ [1: Nt ₂ ] . In addition, Nr is the number of receive antennas, P ₁ and P ₂ are the UE-1 and UE-2 transmit powers, and symbols x _p and x _q are MIMO radio channels H _n Lt; / RTI >

_Here, h _{n (v, τ)} denotes the complex channel impulse response between the Nr receive antennas v size and Nt _n transmission antennas of a size τ. Therefore, the size of the channel matrix H _n can be Nr N Nt _n .

Finally, if w (k) is defined as an AWGN vector, the reception vector can be expressed by the following equation (12).

Here, | h _{1 (v,? = P)} | ² > | h _{2 (v,? = Q)} | ² , it can be clearly understood that UE-1 is a local user terminal (NEU) and UE-2 is a remote user terminal (FEU).

Next, the process of detecting the uplink signal in the base station proposed in the present invention by combining the spatial modulation SM and the non-orthogonal multiple access (NOMA) as described above (i.e., steps 110 to 150) The combination of spatial modulation (SM) and non-orthogonal multiple access (NOMA) can provide high spectral efficiency. Hybrid detection for estimating UE symbols and antenna index, as in the system model shown in FIG. 3, Method can be performed.

For example, the total received signal at the receiver can be expressed as Equation (12) above, and the MRRC can be performed on the received vector y (t).

은 다음의 수학식 13과 같이 나타낼 수 있다. 즉, 복수의 사용자 단말로부터 기지국에 수신되는 전체수신신호(y(t))에 대해 MRRC를 수행하여 근거리 사용자 단말(NEU)에 대응하는 근거리 송신 안테나의 제 1 인덱스(

)를 추정할 수 있다(단계110).Then, by assuming that the channel matrix H ₁ is known at the receiver, the estimated antenna index of UE-1

Can be expressed by the following Equation (13). That is, MRRC is performed on the entire received signal y (t) received from the plurality of user terminals to the base station to obtain a first index

) (Step 110).

는 제 1 인덱스를 의미하고, g_f(t)는 g(t)의 f번째 요소를 의미한다.Here, g (t) denotes a column vector, H ₁ ^H denotes a hidden covariance of a channel matrix of a local user terminal, y (t) denotes an entire received signal, P ₁ denotes a local user terminal Transmission power,

Denotes the first index, and g _f (t) denotes the f th element of g (t).

가 정확하다고 가정할 경우, 송신된 심볼은 다음의 수학식 14와 같이 추정될 수 있다. 즉, 제 1 인덱스(

)를 이용하여 근거리 상향 링크 신호에 대응하는 제 1 심볼(

)을 추정하는 방식으로 근거리 상향 링크 신호를 검출할 수 있다(단계120).Next, the estimated antenna index

The transmitted symbol may be estimated as: < EMI ID = 14.0 > That is, the first index (

) Corresponding to the short distance uplink signal using the first symbol (

(Step 120). [0031] In step 120, the local uplink signal is estimated.

은 제 1 심볼을 의미하고,

은 열 벡터 g(t)에서 요소 번호

를 의미하며, Q[.]는 성상도 양자화 함수를 의미한다.From here,

Denotes a first symbol,

(T) < / RTI >

, And Q [.] Denotes constellation quantization function.

"를 제거하기 위해 SIC를 수행할 수 있는데, 완벽한 SIC 시나리오에서는 추정된 심볼

는 x_p와 동일하다고 가정할 수 있지만, 불완전한 SIC 시나리오를 사용하기 때문에 SIC의 나머지 결과는 다음의 수학식 15과 같이 나타낼 수 있다. 즉, 근거리 상향 링크 신호를 이용한 SIC를 수행하여 전체수신신호(y(t))에서 근거리 상향 링크 신호(

)를 제거할 수 있다(단계130).Next, from the received vector y (t), the component "

&Quot; can be performed in a full SIC scenario,

The rest of the results but can be assumed to be the same as x _p, due to the use of incomplete SIC SIC scenario can be expressed as Equation (15) of. That is, the SIC using the short distance uplink signal is performed to calculate the short distance uplink signal (y (t)) from the entire reception signal y

(Step 130).

는 전체수신신호에서 근거리 상향 링크 신호를 제거한 신호를 의미하고,

는 전체수신신호를 의미하며,

는 근거리 상향 링크 신호를 의미하고, P₂는 원거리 사용자 단말의 송신 전력을 의미한다.From here,

Denotes a signal obtained by removing the near-field uplink signal from the entire received signal,

Denotes the entire received signal,

Denotes a short distance uplink signal, and P ₂ denotes a transmission power of a remote user terminal.

)를 추정할 수 있고(단계140), 제 2 인덱스(

)를 이용하여 원거리 상향 링크 신호에 대응하는 제 2 심볼(

)을 추정하는 방식으로 원거리 상향 링크 신호를 검출할 수 있다(단계150).The UE-2 transmission symbol and the antenna index can be expressed by Equation (16) using MLE. That is, MLE is performed on the residual signal from which the near-field uplink signal has been removed, and the second index of the far-field transmission antenna corresponding to the far-end user terminal (FEU)

) (Step 140), and the second index (

) Corresponding to the far-end uplink signal and a second symbol (

(Step 150). ≪ tb >< TABLE >

는 제 2 인덱스를 의미하고,

는 제 2 심볼을 의미하며, x_g는 제 2 심볼의 전체 가능성을 포함하는 벡터를 의미한다.Here, d = 1, ..., Nt ₂ , g = 1, ..., M,

Denotes a second index,

Denotes a second symbol, and x _g denotes a vector including the entire possibility of the second symbol.

Therefore, the present invention can effectively detect an uplink signal transmitted from a plurality of user terminals at a base station using spatial modulation (SM) and non-orthogonal multiple access (NOMA).

The present invention estimates a first index of a short-distance transmission antenna corresponding to a near-end user terminal by performing MRRC on all reception signals received from a plurality of user terminals at a base station, By estimating the first symbol corresponding to the link signal, the local uplink signal transmitted from the local user terminal can be effectively detected.

In addition, the SIC using the local uplink signal detected from the entire received signal is performed to remove the local uplink signal, and the MLE is performed on the residual signal to estimate the second index of the remote transmission antenna corresponding to the remote user terminal And estimating the second symbol corresponding to the far uplink signal using the estimated second index, thereby effectively detecting the far uplink signal transmitted from the far user terminal.

Next, a simulation result obtained by applying the uplink signal detection method in the base station having the above-described procedure will be described with reference to FIG. 4 to FIG. 8. When using bit error transmission and characteristic parameters that are fair for all systems The maximum transmission bit q of each system can be represented as shown in FIG.

에 의해 주어지고,

는 잡음 전력이다.And, in the simulation of the method of detecting the uplink signal at the base station, a complete channel identification can be assumed at the receiver, and the receive antenna can be assumed to be wide enough to avoid correlation and the maximum transmit power, P, , And the signal-to-noise-ratio (SNR) (hereinafter referred to as SNR) at the receiver is the same

Lt; / RTI >

Is the noise power.

In addition, a full BER (bit error rate, hereinafter referred to as BER) simulation parameter may be represented as shown in FIG. 5, where N is the number of UEs paired, M _n is the UE- N _n is the number of transmit antennas, P _n is the normalized UE-n, d _n is the normalized distance of UE-n, v is the path loss index, and h _n is the UE-n channel distribution.

5, for the SM NOMA system model of the present invention and the conventional NOMA system model, it is clear that UE-1 is a local user terminal (NEU) and UE-2 is a remote user terminal (FEU) It can be seen that the SM NOMA system model, a proposed system for a remote user terminal (FEU), outperforms the existing NOMA system model at a given SNR.

It can be seen here that the existing NOMA system model is superior to the proposed SM NOMA system model by approximately 1 dB at BER = 10 ^-3 in the case of the near user terminal (NEU) It can be seen that the estimation is incomplete and the signal of the local user terminal (NEU) is not completely removed during the SIC.

In addition, it can be seen that at a SNR of approximately 17 dB, the far-end user terminal (FEU) of the SM NOMA system model intersects with the near-end user terminal (NEU) of the SM NOMA system model, But because the decoded signal of the local user terminal (NEU) tends to be inaccurate.

On the other hand, the decoded signal of the local user terminal (NEU) of the SM NOMA system model can be used to perform the SIC. If the decoded signal of the local user terminal (NEU) of the SM NOMA system model is incorrect, (NEU) of the SM NOMA system model in the total received signal, and at the high SNR, the decoded signal of the near user terminal (NEU) of the SM NOMA system model is accurately estimated (NEU) of the SM NOMA system model is crossed by the remote user terminal (FEU) of the SM NOMA system model due to the BER performance of the MLE, as shown in FIG. 6 MRRC. ≪ / RTI >

On the other hand, the simulation results of the user and system transmission bits, which can be achieved as shown in FIGS. 7 and 8, are shown. In the case of the user transmission bit achievable as shown in FIG. 7, the near user terminal (NEU) and the far user terminal (FEU) of the SM NOMA system model are connected to the near user terminal (NEU) and the far user terminal FEU).

8, the SM NOMA system model of the present invention shares the same bandwidth for both the near user terminal (NEU) and the far user terminal (FEU), and as shown in FIG. 4, the SM NOMA Because the system model achieves the highest transmission bit, it can be seen that the SM NOMA system model outperforms all other systems at achievable system transmission bits.

As described above, the spatial modulation (SM) and the non-orthogonal multiple access (NOMA) combination (fusion) can be performed in order to detect the uplink signal in the base station. The near user terminal Hybrid detection techniques have been introduced to estimate the symbols and antenna indexes transmitted from the mobile station and spatial modulation (SM) and non-orthogonal multiple access (NOMA) combining (fusion) It can be seen that the combined system of spatial modulation (SM) and non-orthogonal multiple access (NOMA) outperforms all other systems in terms of the performance of the system transmission bits, since more than twice as many bits can be transmitted as compared to other systems have.

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 embodiments, but, on the contrary, It will be readily apparent that such substitutions, modifications, and alterations are possible.

Claims (6)

Estimating a first index of a local transmission antenna corresponding to a local user terminal by performing maximum receive ratio combining (MRRC) on a total reception signal received from a plurality of user terminals to a base station;
Detecting the nearest uplink signal by estimating a first symbol corresponding to the nearest uplink signal using the first index;
Performing successive interference cancellation (SIC) using the short distance uplink signal to remove the short distance uplink signal from the entire received signal;
Performing MLE (Maximum Likelihood Estimation) on the residual signal from which the near-field uplink signal has been removed to estimate a second index of a far-field transmission antenna corresponding to the far-
And detecting the second uplink signal by estimating a second symbol corresponding to the far uplink signal using the second index,
The method of claim 1, wherein estimating the first index comprises: estimating the first index according to the following equation:

Where H (t) denotes a column vector, H ₁ ^H denotes a hidden covariance of a channel matrix of the local user terminal, y (t) denotes the entire received signal, P ₁ denotes a near- Means the transmission power of the user terminal,

Denotes the first index, and g _f (t) denotes the f th element of g (t).
delete The method according to claim 1,
Wherein the step of detecting the near-field uplink signal estimates the first symbol according to the following equation.

From here,

Denotes the first symbol,

(T) < / RTI >

, And Q [.] Denotes constellation quantization function.
The method according to claim 1,
Wherein the step of removing the short distance uplink signal is performed according to the following equation.

From here,

Denotes a signal obtained by removing the near-field uplink signal from the entire received signal,

Means the entire received signal,

Denotes the near-end uplink signal, and P ₂ denotes the transmission power of the remote user terminal.
The method according to claim 1,
Wherein the step of detecting the long distance uplink signal is performed according to the following equation.

Here, d = 1, ..., Nt ₂ , g = 1, ..., M,

Denotes the second index,

Denotes the second symbol, and x _g denotes a vector including the entire possibility of the second symbol.
6. The method according to any one of claims 1 to 5,
Wherein the near user terminal is set to a maximum transmission power at the base station,
Wherein the remote user terminal is set to a relatively low transmission power in the base station.

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