KR20070077709A - Apparatus and Method for Eliminating Cell Interference in Wireless Communication Systems - Google Patents

Abstract

The present invention relates to an apparatus and a method for canceling neighboring cell interference in a wireless communication system. The present invention relates to a method for canceling interference in a wireless communication system, comprising: receiving transmission signals of predetermined base stations through a plurality of receiving antennas; Calculating a mean square error for the received signal, determining whether to perform sequential interference cancellation on the interference signal of the interfering base stations corresponding to the calculated mean square error, and averaging according to the determination result. Estimating a transmission signal of the serving base station using the square error.

Description

Apparatus and method for eliminating cell interference in wireless communication systems {APPARATUS AND METHOD FOR INTERFERENCE CANCELLATION IN A WIRELESS COMMUNICATION SYSTEM}

1 illustrates an example of a wireless communication system contemplated in accordance with an embodiment of the present invention;

2 is a diagram schematically illustrating a configuration of a receiving apparatus for canceling inter-cell interference according to an embodiment of the present invention;

3 is a diagram illustrating an interference cancellation process in a wireless communication system according to an embodiment of the present invention;

4 illustrates a performance graph through cell interference cancellation according to an embodiment of the present invention.

TECHNICAL FIELD The present invention relates to a wireless communication system, and more particularly, to an apparatus and method for efficient cell interference cancellation in a multi antenna communication system.

Commonly used technologies for providing data services to users in the current wireless communication environment include CDMA2000 Code Division Multiple Access 2000 1x Evolution Data Optimized (GPDMA), General Packet Radio Services (GPRS), and Universal Mobile Telecommunication Service (UMTS). And wireless LAN technologies such as 2.5 generation or 3 generation cellular mobile communication technology, and IEEE (Institute of Electrical and Electronics Engineers) 802.11 wireless local area network (hereinafter referred to as "LAN"). Divided into.

The most prominent feature of the 3rd generation cellular mobile communication technology focused on voice services over a circuit network is that it provides packet data services that enable users to access the Internet in a wide range of wireless communication environments. will be.

In parallel with the evolution of these mobile communication technologies, various short range wireless access technologies such as IEEE 802.16 based wireless LANs are emerging. These techniques do not guarantee the same level of mobility as in cellular mobile communication systems. However, the short range wireless access technologies replace wired communication networks such as cable modems or digital subscriber lines (xDSLs) in hot spot areas or home networks, such as public places or schools. In the meantime, it has been proposed as an alternative for providing a high speed data service in a wireless environment.

However, when providing a high-speed data service over the wireless LAN described above, there are limitations in providing public network services to users due to radio interference, as well as extremely limited mobility and narrow service area.

Therefore, efforts to overcome the above limitations have been made at various angles. For example, researches on portable Internet technologies that complement the advantages and disadvantages of cellular mobile communication systems and wireless LANs are being actively conducted. As a representative example of the portable Internet technology, which is currently being standardized and developed, researches on a wireless broadband Internet (WiBro) system are being actively conducted. The WiBro system can provide high-speed data services in mobile environments such as indoor / outdoor stop environment, walking speed, and medium / low speed (about 60 km / h) using various types of mobile terminals (MS).

On the other hand, in the wireless communication system as described above, active research for providing various quality of service (hereinafter, referred to as 'QoS') to users is in progress. In addition, wireless communication systems require high-speed mass communication systems capable of processing and transmitting a variety of information such as video and wireless data beyond voice-oriented services. Therefore, by increasing the system transmission efficiency, an appropriate channel coding method for improving system performance becomes an essential element.

However, unlike a wired channel environment, a wireless channel environment exists in a wireless communication system such as multipath interference, shadowing, propagation attenuation, time varying noise, interference, and fading. Many factors lead to unavoidable errors and loss of information. The loss of information causes severe distortion in the actual transmission signal, thereby degrading the overall performance of the wireless communication system.

As described above, an interference signal is generated in a wireless communication system, and this interference signal has a great influence on system performance. An example is the cell edge region of a system with a frequency reuse factor of one. In such a cell boundary region, the neighboring base station uses the same frequency in addition to the reception signal from a base station (BS), for example, a serving base station (BS), to which a mobile station (MS) is connected and receiving information. There will be a signal sent to the other user. Such a signal acts as an interference signal directly to the mobile terminal, resulting in a decrease in reception performance of the mobile terminal.

Typically, in a wireless communication system such as a code division multiple access (hereinafter referred to as "CDMA") or orthogonal frequency division multiplexing (hereinafter referred to as "OFDM") based system. Frequency reuse factor 1 is used to improve frequency efficiency and facilitate cell planning. However, in the cell boundary overlap region, the signal of the serving base station and the interference signal of the neighboring base station are overlapped with similar power and received by the mobile terminal. Therefore, the mobile terminal has a problem in that the link performance is seriously degraded due to mutual interference by the neighboring base stations.

As described above, in the wireless communication system, the efficiency of use of frequency resources is increased through a frequency reuse factor. The frequency reuse coefficient refers to an index indicating how far apart two base stations (BS) use the same frequency resource. That is, the frequency reuse coefficient indicates how far apart the frequency band used by a particular base station is geographically reused and may have a different value depending on the system.

In general, as the frequency reuse coefficient is increased, interference between cells is reduced, but the frequency use efficiency is lowered. On the contrary, the smaller the frequency reuse coefficient is, the higher the frequency use efficiency is, but there is a disadvantage in that inter-cell interference increases.

That is, as the frequency reuse coefficient is increased, signal to interference & noise ratio (hereinafter referred to as 'SINR') in the cell boundary region increases to secure reception performance in the cell boundary region. However, in this case, since the same frequency resources are not used by neighboring base stations, there is a disadvantage in that the frequency use efficiency is lowered.

On the contrary, when the frequency reuse factor is 1, since the neighboring base stations all use the same frequency band, the frequency use efficiency can be maximized. However, in this case, the SINR is reduced due to the increase in the interference power at the cell boundary region.

For example, the CDMA system uses the frequency reuse factor 1 as it is robust against interference of neighboring base stations through a spreading / despreading process. However, in such a case, there is also a disadvantage in that interference between adjacent cells cannot be reduced because spreading / despreading gain does not exist in a full loading situation.

In addition, in the OFDM system, which has been recently adopted for high frequency use efficiency, the spreading / despreading technique used in the CDMA system is not applied. Therefore, when the frequency reuse factor is set to 1, performance is degraded due to interference signals received from adjacent cells at the cell boundary. Therefore, there is a need for a method capable of eliminating neighboring cell interference in such an environment.

In the OFDM system, techniques such as partial loading and fractional frequency reuse have been proposed. However, since these techniques do not use all of the used frequency resources, the frequency use efficiency is inferior. In addition, the techniques such as partial loading and partial frequency reuse are difficult to be applied to an actual system because coordination between neighboring cells is necessary. Therefore, in recent years, various methods for reducing interference by neighboring cells have been actively developed. Is being studied.

For example, while the neighboring base stations use different interleavers, an interleave division multiple access (IDMA) scheme has been proposed in which iterative detection and decoding is applied to eliminate neighboring cell interference. In the IDMA scheme, neighboring base stations reduce neighboring cell interference by using different scramble codes, which must be accompanied by an iterative decoding process. For this reason, the IDMA technique has a disadvantage in that the complexity of a mobile station (MS) is greatly increased.

Therefore, there is an urgent need for an efficient inter-cell interference cancellation method that can improve the reception performance by removing the inter-cell interference in a wireless communication system.

Accordingly, the present invention has been made to solve the aforementioned problems of the prior art, and an object of the present invention is to provide an apparatus and method for efficient intercell interference cancellation in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for improving reception performance through intercell interference cancellation in a wireless communication system.

It is still another object of the present invention to provide an apparatus and method for canceling cell interference using multiple reception antennas in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for improving reception performance by eliminating interference between adjacent cells by modifying a multiple antenna scheme in a wireless communication system.

Another object of the present invention is to provide an interference cancellation apparatus and method considering neighbor cell interference in a MIMO system.

A method according to an embodiment of the present invention for achieving the above object, in the interference cancellation method in a wireless communication system, receiving the transmission signals of a plurality of base stations through a plurality of receiving antennas, and for the received signal Calculating a mean squared error; determining whether sequential interference cancellation is performed on the interference signals of the interfering base stations according to the calculated mean squared error; and a serving base station using the mean squared error corresponding to the determination result. Estimating a transmission signal of the apparatus.

An apparatus according to an embodiment of the present invention for achieving the above object, in the interference cancellation apparatus in a wireless communication system, a plurality of antennas for receiving each of the transmission signals of the base stations, and through the plurality of antennas A channel estimator for estimating a channel for the received signal, an MSE detector for detecting a mean square error (MSE) from the estimated received signal, and a sequential signal for interference signals of adjacent base stations corresponding to the MSE detected by the MSE detector SIC determiner for determining whether to perform the interference cancellation (SIC) and the first and second estimators for estimating the transmission signal of the serving base station using the mean square error corresponding to the determination result of the SIC determiner.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

Prior to the description of the present invention, the terms or words used in the specification and claims described below should not be construed as being limited to the ordinary or dictionary meanings, and the inventors should consider their own invention in the best way. For the purpose of explanation, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention on the basis of the principle that it can be appropriately defined as the concept of term. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

The present invention relates to an apparatus and a method for canceling cell interference in a wireless communication system. In particular, the embodiment of the present invention relates to an apparatus and method for removing interference between adjacent cells using multiple reception antennas. That is, according to the embodiment of the present invention, the mobile terminal can efficiently remove the interference between adjacent cells through the modification of the multi-antenna technique, thereby increasing the reception performance.

That is, an embodiment of the present invention provides an apparatus and method for canceling interference in consideration of adjacent cell interference in a multiple input multiple output (MIMO) system. To this end, an embodiment of the present invention receives the transmission signals of neighboring base stations, determines whether to apply a sequential interference cancellation (SIC) technique to the received signal, and corresponds to the result By adjusting the mean square error (hereinafter referred to as "MSE") value to improve the reception performance.

An embodiment of the present invention includes a multiple receiving antenna, a channel estimator and an interference canceller in a reception device for interference cancellation between adjacent cells. In the embodiment of the present invention, among the configuration of the above-described receiving apparatus, in particular, the interference canceller is proposed. Hereinafter, a preferred operation embodiment according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 illustrates an example of a wireless communication system contemplated in accordance with an embodiment of the present invention.

Referring to FIG. 1, FIG. 1 illustrates a situation in which a mobile station (MS) 110 communicates with a serving BS, for example, a base station BS1 131. In this case, the mobile terminal 110 receives not only the signal of the serving base station BS1 131 but also the signals transmitted from the BS2 133 and the BS3 135 which are neighbor BSs. In this case, the signals transmitted by the neighbor base stations BS2 133 and BS3 135 act as interference in the receiving device of the mobile terminal 110.

In FIG. 1, the mobile terminal 110 has a predetermined number of M _r multiple receive antennas, for example, the serving base station 131 and M _t antennas of neighboring base stations 133 and 135 serving as interference. Assuming it exists, this may apply a conventional multiple antenna, for example MIMO reception technique. The MIMO technique can be roughly divided into a maximum likelihood (ML) series, which is a nonlinear technique, and a linear technique.

In the embodiment of the present invention, a minimum mean square error (hereinafter, referred to as 'MMSE') series technique is used in consideration of the complexity of the mobile terminal 110. However, the present invention is limited thereto. Since the MMSE technique is applied in consideration of the complexity of the mobile terminal as described above, the present invention can be applied to various techniques according to the MIMO scheme.

)를 가정한다. 이러한 경우 상기 이동 단말기(110)가 수신하는 신호는 하기 <수학식 1>과 같이 나타낼 수 있다.In addition, if, according to the use of the MMSE technique, as the number of the mobile terminal 110 that is multiple receive antennas, wherein M _r is the number of antennas of the base stations that is, equal to or greater than M _t (

Assume). In this case, the signal received by the mobile terminal 110 may be represented by Equation 1 below.

이고, M_r 차원을 가진다. As shown in Equation 1, y represents a received signal received by the mobile terminal 110, H represents a matrix having dimensions (M _r , M _t ), and a channel estimator. Is estimated through. The x represents a signal vector transmitted by each base station and has a dimension M _t . N represents thermal noise and includes interference signals of other base stations that the mobile terminal 110 cannot remove. In this case, the power of n is

And has M _r dimension.

라 할 때,

를 만족하는 MMSE 가중 행렬 G는 하기 <수학식 2>와 같이 나타낼 수 있다.Using Orthogonal Principle, Inferred Transmission Signal

When we say

MMSE weighting matrix G satisfying may be expressed by Equation 2 below.

는 열잡음에 파워를 나타내며, 상기 위 첨자 H는 허미시안(Hermitian)을 나타내며, 상기 N은 열잡음을 나타내며, 상기 I는 단위 행렬을 나타낸다. As shown in Equation 2, G represents an MMSE weighting matrix, H represents a channel matrix, and

Represents power in thermal noise, the superscript H represents Hermitian, N represents thermal noise, and I represents the identity matrix.

Next, a reception apparatus and method for canceling inter-cell interference according to an embodiment of the present invention will be described in consideration of the above circumstances.

2 is a diagram schematically illustrating a configuration of a receiving device for canceling inter-cell interference according to an embodiment of the present invention.

Referring to FIG. 2, the receiving apparatus according to the embodiment of the present invention includes a plurality of receiving antennas 201 to 205 and a plurality of radio frequency (hereinafter, referred to as 'RF') processors ( 211 to 215, and a channel estimator 220 and an interference canceller 230. In addition, the interference canceller 230 according to an embodiment of the present invention includes an MSE detector 231, an SIC determiner 233, an MMSE estimator 235, and an MMSE-SIC estimator 237.

The receiving device receives a signal in which a transmission signal from a serving base station 131 and an interference signal from neighboring base stations 133 and 135 overlap with each other through the multiple antennas 201 to 205. Received and transmitted to the RF processors (211 to 215), respectively. The RF processors 211 to 215 perform RF processing on the received signals and transmit the RF signals to the channel estimator 220 and the interference canceller 230.

The channel estimator 220 then performs channel estimation on the received signals and passes the result to the interference canceller 230.

를 통해 구할 수 있다. 즉, 상기 <수학식 2>의 첫 번째 성분인

는 MSE를 나타내며, 상기 MSE 검출기(231)의 출력은 하기 <수학식 3>과 같이 나타낼 수 있다.The interference canceller 230 first detects an MSE from the estimated transmission signals through the MSE detector 231. In this case, the MSE detection is the first component of the MMSE weighting matrix G for obtaining the estimated transmission signals, as shown in Equation (2).

Available through That is, the first component of Equation 2

Denotes MSE, and the output of the MSE detector 231 may be expressed as Equation 3 below.

의 대각 성분(diagonal components)의 합을 나타낸다.In Equation 3, tr (A) is the matrix A, that is, MSE

Sum of the diagonal components of.

Subsequently, the MSE detector 231 transfers the obtained MSE to the SIC determiner 233. Then, the SIC determiner 233 determines whether to perform the SIC by using the MSE transmitted from the MSE detector 231.

For example, first, the MSE _k for a signal transmitted from a kth base station before MMSE estimation may be referred to as a Signal to Interference and Noise Ratio (SINR) hereinafter for a kth base station (SINR _k ). It has a relationship as shown in Equation 4 below.

의 대각 성분 값을 이용할 수 있다. 따라서, 서빙 기지국의 신호를 x₁이라 할 때, 행렬 A의 첫 번째 대각 성분과 나머지 대각 성분의 비교를 통해 SIC를 판단한다. 이때, a_k를 행렬 A의 k 번째 대각 성분이라 할 때, 상기 SIC 판단기(233)는 다음과 같이 SIC 판단을 수행할 수 있다.Therefore, when SIC is added to the MMSE to increase reception performance, when the signal having the largest SINR is detected and removed, the MSE,

Diagonal component values of can be used. Therefore, when the signal of the serving base station is x ₁ , the SIC is determined by comparing the first diagonal component of the matrix A with the remaining diagonal components. In this case, when a _k is a k-th diagonal component of the matrix A, the SIC determiner 233 may perform SIC determination as follows.

First, when the diagonal component a ₁ <min (a ₂ , a ₃ , ..., a _Rt ) is satisfied, the SIC determiner 233 does not perform SIC. That is, in the above case, since the signal of the serving base station is the best in terms of SINR, the SIC is not performed. Here, a ₁ represents an MSE of a serving base station transmission signal and an estimated value, and a ₂ , a ₃ , ..., a _Rt represent an MSE of a transmission signal and an estimated value of neighboring base stations.

Next, when the diagonal component a ₁ > min (a ₂ , a ₃ ,..., A _Rt ) is satisfied, the SIC determiner 233 performs SIC.

Meanwhile, the SIC determiner 233 transfers the result determined through the above procedure to the MMSE estimator 235 or the MMSE-SIC estimator 237. That is, the MMSE estimator 235 and the MMSE-SIC estimator 237 operate according to the determination result of the SIC determiner 233.

When the SIC determiner 233 does not perform the SIC, the MMSE estimator 235 determines the transmission signal of the serving base station using the MMSE solution as it is. Therefore, when the SIC is not performed as described above, the transmission signal of the serving base station is estimated as in Equation 5 below.

은 서빙 기지국의 추정 송신 신호를 나타내며, 상기

는 MMSE 가중 행렬 G의 첫 번째 행 벡터(row vector)를 나타내며, 상기 y는 수신 신호를 나타낸다.As shown in Equation 5,

Represents an estimated transmission signal of the serving base station, and

Denotes the first row vector of the MMSE weighting matrix G, and y denotes the received signal.

In the MMSE-SIC estimator 237, when the SIC determiner 233 performs the SIC, the MSE-SIC estimator 233 estimates the smallest signal and then slices the slice using a slicer. The transmission signal of the serving base station is estimated. To briefly explain this process, the case where M _r = M _t = 2 is as follows. Here, the slicer may be included in the MMSE-SIC estimator to perform a slice function. In addition, the slicer may be configured to be included separately in the interference cancellation device described above.

First, when SIC is performed when M _r = M _t = 2 as described above, the transmission signal of the interfering base station may be estimated as in Equation 6 below.

은 간섭 기지국의 추정 송신 신호를 나타내며, 상기

는 MMSE 가중 행렬 G의 두 번째 행 벡터(row vector)를 나타내며, 상기 y는 수신 신호를 나타낸다. As shown in Equation 6,

Denotes an estimated transmission signal of the interfering base station, and

Denotes a second row vector of the MMSE weighting matrix G, and y denotes a received signal.

를 상기한 바와 같이 소정의 슬라이서를 통과한 신호를

라 할 때, 상기 MMSE-SIC 추정기(237)에서는 상기 <수학식 1>에서 상기

에 해당하는 성분을 제거한다. 이를 표현하면 하기 <수 학식 7>과 같이 나타낼 수 있다.Next, the above estimation estimated by Equation 6

As described above, the signal passing through the predetermined slicer

In the above, MMSE-SIC estimator 237 in the <Equation 1>

Remove the corresponding component. This can be expressed as Equation 7 below.

신호가 제거된 수신 신호를 나타내며, 상기 y는 수신 신호를 나타내며, 상기 h₂는 채널 행렬 H의 2번째 열 벡터(column vector)를 나타내며, 상기

은 간섭 기지국의 추정 송신 신호를 나타낸다.As shown in Equation 7, y _s has passed through the slice in the received signal.

Signal represents a received signal from which the signal has been removed, y represents a received signal, h ₂ represents a second column vector of the channel matrix H, and

Denotes an estimated transmission signal of the interfering base station.

In this case, the MMSE-SIC estimator 237 estimates a signal of a serving base station by MRC (maximum ration combining) the signal y _s . If this process is expressed by an equation, it may be expressed as Equation 8 below.

은 서빙 기지국의 추정 신호를 나타내며, 상기 h₁은 채널 행렬 H의 1번째 열 벡터를 나타내며, 상기 y_s는 수신 신호에서 슬라이스를 통과한

신호가 제거된 수신 신호를 나타내며, 상기 위 첨자 H는 허미시안(Hermitian)을 나타낸다.As shown in Equation 8,

Denotes an estimated signal of a serving base station, h ₁ denotes a first column vector of the channel matrix H, and y _s denotes a signal passed through a slice in a received signal.

The signal represents the received signal from which the superscript H is removed, and the superscript H represents Hermitian.

On the other hand, the interference cancellation apparatus according to the embodiment of the present invention as described above, in performing the interference cancellation of the neighboring base stations, preferably a predetermined number of subcarriers (ie, tones) in a specific time period It is more preferable to perform each tone). However, the present invention is not limited thereto. Next, the interference cancellation method according to the embodiment of the present invention as described above will be described with reference to FIG. 3.

3 is a diagram illustrating an interference cancellation process in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 3, first, in step 301, the reception apparatus according to an embodiment of the present invention proceeds to step 303 when at least one transmission signal is received through a plurality of multiple antennas. In this case, the transmission signal includes a transmission signal from a serving base station or a signal in which an interference signal from neighboring base stations and a transmission signal from the serving base station overlap, and the receiving apparatus includes the plurality of base stations through a plurality of receiving antennas Receive signals transmitted from each other. In step 303, the receiving apparatus performs channel estimation on the received signal, and then proceeds to step 305.

In step 305, the receiving apparatus detects an MSE from the estimated transmission signal, and then proceeds to step 307. In step 307, it is determined whether to perform SIC using the detected MSE, and then proceeds to step 309 or 311 according to the result.

In other words, if the determination is not performed in step 307, the process proceeds to step 309 to estimate the minimum MSE. In this case, when the MSE is not performed in step 307, the MSE estimation is performed by applying the MMSE solution as it is, and then proceeding to step 317 after estimating the MSE having the minimum value. In step 317, the signal of the serving base station is estimated using the estimated value.

On the other hand, when performing the SIC in step 307, after estimating the MSE having the minimum value proceeds to step 313. In step 313, the MSE is sliced, and then step 315 is performed. In step 315, the value sliced in step 313 is removed from the received signal, and then step 317 is performed. In step 317, the transmission signal of the serving base station is estimated using the sliced value as in step 315.

4 is a diagram illustrating a performance graph through cell interference cancellation according to an embodiment of the present invention.

Referring to FIG. 4, FIG. 4 shows a bit error rate (BER) performance graph according to an embodiment of the present invention, where M _r = M _t = 2 and a two-cell environment. It is assumed. In addition, the channel assumes a Rayleigh fading channel, and assumes that both base stations transmit using Binary Phase Shift Keying (BPSK). In addition, it is assumed that the channel is perfectly known at the receiver and assumes an uncoded situation.

In addition, in FIG. 4, the SIC and the MMSE are compared using the maximum ratio combining (MRC) technique for comparison with other techniques. In the case where the interference was completely removed to know the bound), the MRC case was considered.

인 경우 본 발명에서 제안하는 방법은 성능 바운드를 의미하는 간섭이 없을 때, 상기 MRC한 경우와 비교하여 약 2dB의 성능 열화가 있다. 다른 기법과 비교하면 MMSE를 사용하는 경우에 비해 약 8dB 성능 이득이 있고, MRC 기법을 이용해 SIC를 하는 경우보다 현저히 우수한 성능 이득이 있음을 알 수 있다. 4 illustrates a performance graph according to the above case, and it can be seen that the proposed method effectively removes neighboring base station interference as shown in FIG. 4. Specifically, BER

In the case of the method proposed in the present invention, when there is no interference which means performance bound, there is a performance degradation of about 2 dB compared to the case of the MRC. Compared with other techniques, it can be seen that there is about 8dB performance gain compared to using MMSE, and significantly better performance than SIC using MRC technique.

As described above, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are of course possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below, but also by the equivalents of the claims.

According to the apparatus and method for removing cell interference in the wireless communication system of the present invention proposed as described above, it is possible to effectively remove the interference of the neighboring base station in the wireless communication system, thereby improving the reception performance. In addition, by enabling the use of higher coding rates or modulation orders through the reception performance improvement, there is an advantage of improving the overall system throughput.

Claims (23)

In the interference cancellation method in a wireless communication system, Receiving transmission signals of predetermined base stations through a plurality of receiving antennas, Calculating a mean square error for the received signals; Determining whether to perform sequential interference cancellation on the interference signals of the interfering base stations corresponding to the average square error calculated; Estimating a transmission signal of a serving base station using a mean square error corresponding to the determination result. The method of claim 1, Estimating a transmission signal of the serving base station using the minimum mean square error when the sequential interference cancellation is not performed. The method of claim 2, The estimated transmission signal of the serving base station is represented as follows.

Represents an estimated transmission signal of the serving base station,

Is the first row vector of the minimum mean squared error (MMSE) weighting matrix, and y is the received signal. The method of claim 1, Estimating an interference signal of a neighbor base station having a minimum mean square error when performing sequential interference cancellation as a result of the determination; And after slicing the estimated signal, determining a transmission signal of a serving base station using the sliced value. The method of claim 4, wherein The determination process, Removing the sliced signal from the received signals from the base stations; Estimating a transmission signal of the serving base station based on the received signal from which the slice signal has been removed. The method of claim 5, The estimated signal of the interference base station is represented as follows.

Denotes the estimated transmission signal of the interfering base station,

Denotes the second row vector of the MMSE weighting matrix, and y denotes the received signal. The method of claim 5, The signal from which the sliced signal is removed from the received signal is represented as follows.

y _s passes the slice in the received signal

Signal represents the received signal from which the signal has been removed, y represents the received signal, h ₂ represents the second column vector of the channel matrix H,

Denotes the estimated transmission signal of the interfering base station. The method of claim 5, The estimated transmission signal of the serving base station is represented as follows.

Denotes the estimated signal of the serving base station, h ₁ denotes the first column vector of the channel matrix H, and y _s denotes that the slice passes the slice in the received signal.

Represents the received signal from which the signal has been removed, and the superscript H represents Hermitian. The method of claim 1, The determination of whether or not the sequential interference cancellation comprises: comparing the interference signal received from the interfering base station with the magnitude of the received signal received from the serving base station in the received signal. The method of claim 9, And the magnitude of the signal is determined by detecting a signal-to-interference noise ratio (SINR). The method of claim 1, The transmission signal of the predetermined base stations includes a signal in which the transmission signal of the serving base station or the transmission signal of the serving base station and the interference signal of neighboring base stations overlap. An interference cancellation apparatus in a wireless communication system, A plurality of antennas each receiving transmission signals of predetermined base stations, A channel estimator for estimating a channel for received signals received through the plurality of antennas; An MSE detector for detecting a mean square error (MSE) for the estimated received signals; An SIC determiner for determining whether to perform sequential interference cancellation (SIC) on interference signals of adjacent base stations according to the MSE detected by the MSE detector; And first and second estimators for estimating the transmission signal of the serving base station using the mean square error corresponding to the determination result of the SIC determiner. The method of claim 12, And the first estimator comprises an MMSE estimator for estimating a transmission signal of a serving base station using a minimum mean square error when the SIC determiner does not perform the SIC. The method of claim 13, And an estimated transmission signal of the serving base station estimated by the first estimator is represented as follows.

Represents an estimated transmission signal of the serving base station,

Is the first row vector of the minimum mean squared error (MMSE) weighting matrix, and y is the received signal. The method of claim 12, The second estimator estimates an interference signal of a neighboring base station having a minimum mean square error when performing the SIC as a result of the determination by the SIC determiner, slices the estimated signal, and then decodes the sliced value. And an MMSE-SIC estimator for estimating a transmission signal of the serving base station by using the interference elimination apparatus. The method of claim 15, And the second estimator removes the sliced signal from the received signals from the base stations and estimates a transmission signal of the serving base station based on the received signal from which the slice signal has been removed. The method of claim 16, And the estimated signal of the interfering base station estimated by the second estimator is represented as follows.

Denotes the estimated transmission signal of the interfering base station,

Denotes the second row vector of the MMSE weighting matrix, and y denotes the received signal. The method of claim 16, And the signal from which the sliced signal is removed in the second estimator is represented as follows.

y _s passes the slice in the received signal

Signal represents the received signal from which the signal has been removed, y represents the received signal, h ₂ represents the second column vector of the channel matrix H,

Denotes the estimated transmission signal of the interfering base station. The method of claim 16, And the estimated transmission signal of the serving base station estimated by the second estimator is represented as follows.

Denotes the estimated signal of the serving base station, h ₁ denotes the first column vector of the channel matrix H, and y _s denotes that the slice passes the slice in the received signal.

Represents the received signal from which the signal has been removed, and the superscript H represents Hermitian. The method of claim 16, And the second estimator comprises a slicer that removes the sliced signal from received signals from the base stations. The method of claim 12, The SIC determination of the SIC determiner, the interference elimination apparatus, characterized in that by comparing the size of the received signal received from the serving base station and the interference signal received from the interference base station. The method of claim 21, The SIC determiner detects a signal-to-interference noise ratio (SINR) to determine the magnitude of the signal. The method of claim 12, And the interference cancellation device comprises a slicer for removing the sliced signal from the received signals from the base stations.

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