KR20150112399A - Method for transmitting uplink data and apparatus for the same - Google Patents

Abstract

Disclosed are a method and an apparatus for transmitting uplink data. The method for transmitting uplink data may include the steps of: multiplying data symbol by ZCZ code; generating a transmission symbol by performing a reverse FFT with respect to the data symbol multiplied by the ZCZ code; diffusing the transmission symbol on the time axis as much as the length of the ZCZ code; and transmitting the diffused transmission symbol. Therefore, in an OFDMA-based cooperative base station communication system, time error between users due to uplink data transmission can be minimized.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for transmitting uplink data,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uplink data transmission technique, and more particularly, to an uplink cooperative base station (OFDMA) technique for maximizing diversity in an environment where a time error exists.

BACKGROUND ART [0002] In recent years, a demand for a high transmission rate and a service quality of a mobile communication system has been demanded as a usage amount for a large number of mobile communication devices including a smart phone has increased sharply. To this end, it is necessary to provide high-quality data services to users (i.e. terminals) located in the shadow area or the cell boundary. However, even if the user is close to the base station, there is a problem that the intensity of the signal is drastically reduced when the user is located in the shadow area. In addition, if the user is located at the cell boundary, serious performance degradation may occur due to interference from neighboring cells. Studies are underway to utilize the diversity gain of the base station cooperative communication to provide a high quality mobile communication service to the users located in the cell boundary or the propagation shadow area.

Generally, in the uplink, a separate synchronization process (i.e., a ranging process) is required to minimize the synchronization error between users unlike in the downlink. That is, since the base station synchronizes the signals to be transmitted to all users in the downlink and then transmits them in a batch, the orthogonality between the signals of the users is maintained regardless of the distance and reception timing of each user.

On the other hand, in the uplink, signals of users located at different positions from each base station are received at different timings. This destroys the orthogonality of the signals between users, which is a major cause of performance degradation. In order to prevent this, in the uplink, the transmission timing of each user is appropriately adjusted to minimize the time synchronization error (i.e., the ranging process).

However, it is impossible to apply the synchronization process in the uplink cooperative base station communication. That is, the optimal transmission timing determined in consideration of the distance of each user in one base station can not be the optimal transmission timing in other base stations. Therefore, in any one of the base stations, there is a time error between the users, and therefore the cooperative diversity gain, which is the main purpose of the cooperative base station communication system, can not be obtained sufficiently.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission / reception method for eliminating interference even in an environment where there is a time error between users in uplink data transmission.

Another object of the present invention is to provide a data transmission / reception apparatus for eliminating interference even in an environment where there is a time error between users in uplink data transmission.

According to an aspect of the present invention, there is provided an uplink data transmission method including multiplying a data symbol by a ZCZ code, performing an inverse fast Fourier transform (FFT) on a data symbol multiplied by the ZCZ code IFFT) to generate a transmission symbol, spreading the transmission symbol on a time axis by the length of the ZCZ code, and transmitting the spread transmission symbol.

Here, the data symbol multiplied by the ZCZ code may be generated by multiplying all the subcarriers by the same ZCZ code.

Here, the ZCZ code may have zero correlation within a delay range for one chip.

Here, the length of the ZCZ code may be the number of consecutive OFDM symbols to be transmitted by the UE.

Here, the transmission symbol may be generated by performing the IFFT on all subcarriers.

According to another aspect of the present invention, there is provided an uplink data reception method, comprising: receiving a signal; despreading the signal based on a ZCZ code to detect a received symbol; Performing Fast Fourier Transform (FFT) on the received symbol, and detecting a data symbol from the received symbol on which the FFT has been performed.

Here, the signal may be a signal spread over a time axis by the length of the ZCZ code.

Here, the ZCZ code may have zero correlation within a delay range for one chip.

According to another aspect of the present invention, there is provided a terminal for performing a reverse fast Fourier transform (IFFT) on a data symbol multiplied by a ZCZ code with a ZCZ code, A processing unit for generating transmission symbols, spreading the transmission symbols on a time axis by a length of the ZCZ code, transmitting spread transmission symbols, and a storage unit for storing information stored in the processing unit and information to be stored.

Here, the data symbol multiplied by the ZCZ code may be generated by multiplying all the subcarriers by the same ZCZ code.

Here, the ZCZ code may have zero correlation within a delay range for one chip.

Here, the length of the ZCZ code may be the number of consecutive OFDM symbols to be transmitted by the UE.

Here, the transmission symbol may be generated by performing the IFFT on all subcarriers.

According to the present invention, in the OFDMA-based cooperative base station communication system, a time error between users due to uplink data transmission can be minimized. As a result, the base station can sufficiently obtain the cooperative diversity gain.

In addition, since the base station does not need to discriminate the distance with the user every time for the ranging process, the complexity and the power consumption can be reduced.

1 is a conceptual diagram illustrating an uplink collaborative base station system.
2 is a flowchart illustrating an uplink data transmission method according to an embodiment of the present invention.
3 is a conceptual diagram illustrating an OFDM symbol structure according to the conventional OFDMA scheme.
4 is a conceptual diagram illustrating an OFDM symbol structure according to an embodiment of the present invention.
5 is a flowchart illustrating an uplink data receiving method according to an embodiment of the present invention.
6 is a block diagram illustrating a terminal according to an embodiment of the present invention.
FIG. 7 is a graph illustrating performance of the uplink data transmission / reception method and the sparse SC-FDMA scheme according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, the network can be, for example, a wireless Internet such as WiFi (wireless fidelity), a wireless broadband internet (WiBro) or a portable internet such as world interoperability for microwave access (WiMax) A 3G mobile communication network such as Wideband Code Division Multiple Access (WCDMA) or CDMA2000, a high speed downlink packet access (HSDPA), or a high speed uplink packet access (HSUPA) A 3.5G mobile communication network, a 4G mobile communication network such as an LTE (Long Term Evolution) network or an LTE-Advanced network, and a 5G mobile communication network.

Throughout the specification, a terminal is referred to as a mobile station, a mobile terminal, a subscriber station, a portable subscriber station, a user equipment, an access terminal, And may include all or some of the functions of a terminal, a mobile station, a mobile terminal, a subscriber station, a mobile subscriber station, a user equipment, an access terminal, and the like.

Here, a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch, smart watch, smart glass, e-book reader, portable multimedia player (PMP), portable game machine, navigation device, digital camera, digital multimedia broadcasting (DMB) A digital audio recorder, a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player ) Can be used.

Throughout the specification, a base station is referred to as an access point, a radio access station, a node B, an evolved node B, a base transceiver station, an MMR mobile multihop relay) -BS, and may include all or some of the functions of a base station, an access point, a radio access station, a Node B, an eNodeB, a base transceiver station, and a MMR-BS.

Next, a data transmission / reception method will be described after the communication system is defined first. Here, the communication system may be applied to the uplink data transmission and reception method and apparatus according to an embodiment of the present invention.

로 나타낼 수 있으며,

는 가장 가까운 정수로 내림하는 연산자로서 N을 정수로 만들기 위해 사용될 수 있다.The communication system assumes that a total of P users (i. E., Terminals) are present in an even distribution within M cells of radius R-km, and that there is no interference between cells. The total number of subcarriers is represented by N _c , and the number of subcarriers used by one user is denoted by N. In this case,

Lt; / RTI >

Is an operator that rounds down to the nearest integer and can be used to make N an integer.

로 표기한다. 즉,

는 N-포인트(point) 역 고속 푸리에 변환(inverse fast fourier transform, IFFT)의 입력이 되며,

을 OFDM 변환한 p번째 사용자의 u번째 송신 심볼

은 아래 수학식 1과 같이 나타낼 수 있다.Also, a data symbol transmitted by the k-th subcarrier in the u-th orthogonal frequency division multiplexing (OFDM) symbol of one frame of the p-th user

. In other words,

Is an input of an N-point inverse fast fourier transform (IFFT)

Th user < RTI ID = 0.0 >

Can be expressed by Equation (1) below.

Here, T _g is the length of the guard interval, and the length of the OFDM symbol not including the guard interval is denoted by T _s . That is, if the length of the OFDM symbol including the guard interval is T, T = T _s + T _g . Also, f _k is the frequency of the k-th subcarrier, and is calculated by f _k = k / T _s . In addition, C ^(p) is a sub-carrier index determined for the user, and the sub-carrier index can be adjusted according to the number of users in the cell. The OFDM symbol x ^(p) (t) of the p-th user having consecutive N _F OFDM symbols can be expressed by Equation (2) below.

Further, the i-th base station and has a p-th mark the distance between the user to d ^{(i, p),} and d ^{(i, p)} is independent and uniform distribution in the R-km range from the center of the base station. Here, it is assumed that there is no component of the signal attenuated by the distance by performing the power control ideally, and only the attenuation due to the flat fading exists. Therefore, the OFDM symbol can reach each base station after experiencing the channel function H ^{(i, p)} between the i-th base station and the p-th user. At this time, the received signal r ⁽ⁱ⁾ (t) arriving at the i-th base station can be expressed by Equation (3) below.

이고, w⁽ⁱ⁾(t)는 전력 스펙트럼 밀도가 N₀/2인 i번째 기지국에 더해진 복소 부가 백색 가우스 잡읍(additive white gaussian noise, AWGN) 신호이다.Here, r ^{(i, p)} is the signal of the p-th user received at the i-th base station

And, w ^{(i) (t)} is complex additive white Gaussian japeup (additive white gaussian noise, AWGN) the signal is added to the power spectral density N _0/2 of the i-th base station.

을 통해 계산될 수 있다. 여기서, τ^(i,p)는 각 사용자들이 동시에 전송하지 않고 독립적으로 전송함으로 인해 발생하는 지연으로 [0 T_s/10] 범위 내에 균등한 분포를 갖고 랜덤하게 발생한다고 가정한다.In addition, t ^{(i, p)} is i is the time difference between the reference time and the p-th user of the second base station, considering the speed of light c and the distance and the transmission timing (timing) of each user among the base station and the user τ ^{(i, p)} . That is, t ^{(i, p)}

Lt; / RTI > Here, it is assumed that τ ^{(i, p)} is a delay caused by independently transmitting each user without transmitting simultaneously, and is randomly generated with an even distribution within a range of [0 T _s / 10].

는 아래 수학식 4와 같다.In the demodulation process, a k-th fast fourier transform (FFT) output from the u-th OFDM symbol of the received signal of the p-th user of the i-th base station

Is expressed by Equation (4) below.

를 i번째 기지국과 p번째 사용자의 주파수 채널 함수 H^(i,p)를 ZF(zero forcing) 또는 MMSE(minimum mean square error)를 이용하여 보상함으로써 아래 수학식 5와 같이 양자화 과정 이전의 검출 신호

를 얻을 수 있다.here,

Is compensated for by using ZF (zero forcing) or MMSE (minimum mean square error) for the frequency channel function H ^{(i, p)} of the i-th base station and the p-th user ^,

Can be obtained.

의 채널보상을 하기 위한 계수이다. 최종적으로, 각 기지국에서 검출한 신호

를 평균한 후, 양자화 연산자 Q(ㆍ)를 통해 최종 검출 심볼

을 아래 수학식 6과 같이 얻을 수 있다.Here, Z ^{(i, p)} is obtained through ZF or MMSE

Is a coefficient for channel compensation. Finally, the signal detected by each base station

And then the quantization operator Q ()

Can be obtained as shown in Equation (6) below.

On the other hand, as shown in Equation (3), the orthogonality of the subcarriers can be destroyed because the signals of the respective users are received at different times. In order to prevent this, the base station determines each user's distance, then transmits the signal of the user farthest away first, and transmits the signal of the nearest user later (i.e., a ranging technique) Thereby minimizing the time difference between the signals of the two.

In a single base station system, this process can be performed without difficulty, but it is difficult to apply such a ranging scheme in a cooperative base station system.

1 is a conceptual diagram illustrating an uplink collaborative base station system.

1, the numbers on the dashed lines between the base stations 100 and 200 and the terminals 10, 20 and 30 indicate the distance between the base stations 100 and 200 and the respective terminals 10, 20 and 30 The transmission order to be performed when considered. The first base station 100 requests the first terminal 10 that is farthest from the first base station 100 to transmit the transmission signal first and requests the second terminal 20 closest to the first terminal 10 to transmit the transmission signal latest. However, when each of the terminals 10, 20, and 30 transmits at this transmission timing, a serious synchronization error occurs in the second base station 200.

The first terminal 10 which is the first to transmit a transmission signal from the first base station 100 is located closest to the second base station 200 and the transmission signal is transmitted from the first base station 100 The second terminal 20 to be transmitted latest is located at the farthest distance from the second base station 200. Therefore, it is not easy to perform a time synchronization process to satisfy all the base stations 100 and 200 at the same time.

2 is a flowchart illustrating an uplink data transmission method according to an embodiment of the present invention. The following description will be made using the same notation used in the description of the communication system.

Referring to FIG. 2, a terminal may multiply a data symbol by a zero correlation zone (ZCZ) code (S100). A ZCZ code may have zero correlation within a delay range for one chip. The spreading factor (SF) of the ZCZ code can be set to N _F (i.e., the number of consecutive OFDM symbols to be transmitted by the UE) to use the same resources as the existing OFDMA (orthogonal frequency division multiplex access).

이고,

는 가장 가까운 2의 멱승으로 올림해주는 연산이다. 예를 들어,

와 같이 나타낼 수 있다.If SF is set to 2P '

ego,

Is an operation that rounds up to the nearest power of 2. E.g,

As shown in Fig.

는 u에 상관없이 0≤u<N_F-1에서 모두 동일하다. 즉,

이라 할 수 있으므로,

를

로 표기할 수 있다. ZCZ 코드 기반의 OFDMA 기법에서 p번째 사용자(즉, 단말)의 k번째 부반송파에 의해 전송될 ZCZ 코드가 곱해진 데이터 심볼(즉, IFFT 입력이 될 신호)은 아래 수학식 7과 같다.Meanwhile, in one embodiment of the present invention, the data symbols are spread on the time axis into N _F OFDM symbols

Are all the same in 0? U < N _F -1 regardless of u. In other words,

Therefore,

To

. In the ZCZ code-based OFDMA technique, a data symbol (i.e., a signal to be an IFFT input) multiplied by a ZCZ code to be transmitted by a k-th subcarrier of a pth user (i.e., a UE) is expressed by Equation (7).

는 p번째 사용자의 ZCZ 코드의 u번째 칩으로써 모든 부판송파에 동일하게 곱해진다.here,

Is multiplied equally to all subcarriers as the u-th chip of the ZCZ code of the p-th user.

)은 p번째 사용자의 u번째 칩에 의해 출력되고, 아래 수학식 8과 같다.The terminal may perform an inverse fast Fourier transform (IFFT) on the data symbol multiplied by the ZCZ code to generate a transmission symbol (S110). Here, the transmission symbol may be generated by performing an IFFT transform on all subcarriers. As shown in Equation (1) described in the communication system, a transmission symbol

) Is output by the u &lt; th &gt; chip of the p &lt; th &gt;

은 아래 수학식 9와 같다.The terminal may spread the transmission symbol on the time axis by the length of the ZCZ code (S120). The OFDM symbol spread in the time domain

Is expressed by Equation (9) below.

The UE can transmit the spread transmission symbol (S130).

In this way, by applying the ZCZ code to the OFDM signal, the terminal can prevent interference with other terminals even if a time error within ± 1 OFDM symbol occurs.

Next, an OFDM symbol structure according to the conventional OFDMA scheme and a structure of an OFDM symbol according to an embodiment of the present invention will be described.

FIG. 3 is a conceptual diagram illustrating an OFDM symbol structure according to the conventional OFDMA scheme, and FIG. 4 is a conceptual diagram illustrating an OFDM symbol structure according to an embodiment of the present invention.

는 k번째 사용자의 l번째 데이터 심볼을 의미하고,

는 k번째 사용자의 길이가 N인 ZCZ 코드의 u번째 칩을 의미한다. 또한, ZCZ 코드 한 칩의 길이(T_c)가 한 OFDM 심볼 길이(T_s)와 같다. 기존 OFDMA 방식은 다수의 사용자들이 전체 부반송파를 주파수 축에서 나누어 사용한다. 반면, 본 발명의 일 실시예에 따른 ZCZ 코드 시간-확산 OFDMA 방식은 각 사용자들이 전체 부반송파를 동시에 사용하고, 확산 코드를 통해 각 사용자의 신호를 구분할 수 있게 한다.
Referring to Figures 3 and 4,

Denotes the l-th data symbol of the k-th user,

Denotes the u-th chip of the ZCZ code having a length k of the k-th user. Further, the length (T _c ) of one chip of the ZCZ code is equal to one OFDM symbol length (T _s ). In the conventional OFDMA scheme, a plurality of users divides all subcarriers on the frequency axis. On the other hand, the ZCZ code time-spreading OFDMA scheme according to an embodiment of the present invention enables each user to simultaneously use all subcarriers and distinguish signals of each user through a spreading code.

5 is a flowchart illustrating an uplink data receiving method according to an embodiment of the present invention.

Referring to FIG. 5, the uplink data reception method may be performed in the reverse order of the procedure described with reference to FIG. The base station can receive a signal from an arbitrary terminal (S200), perform despreading on the signal based on the ZCZ code, and detect the received symbol (S210). Here, the signal may mean a signal spread on the time axis by the length of the ZCZ code. The ZCZ code may have zero correlation within a delay range for one chip.

The base station may perform an FFT on the received symbol (S220) and may detect the final data symbol from the received symbol on which the FFT has been performed (S230).

That is, the base station performs despreading using the ZCZ code in the demodulation process, and then detects the final symbol based on Equations (4) to (6) described above.

Accordingly, even if the base station does not additionally apply the transmission time to each of the UEs, the interference between the UEs does not occur, so that the spatial diversity gain through the cooperative base station system can be expected to be maximized. In addition, since the base station does not have to measure the distance to the terminal necessary for time synchronization every time, unnecessary power consumption can be prevented.

6 is a block diagram illustrating a terminal according to an embodiment of the present invention.

Referring to FIG. 6, the terminal 10 may include a processing unit 11 and a storage unit 12.

The processing unit 11 may multiply the data symbol by the ZCZ code, and the specific process of multiplying the ZCZ code may be the same as the step S100 of FIG. 2 described above. Here, the data symbol multiplied by the ZCZ code can be generated by multiplying all subcarriers by the same ZCZ code. The ZCZ code may have zero correlation within a delay range for one chip, and the length of the ZCZ code may mean the number of consecutive OFDM symbols to be transmitted by the UE.

The processing unit 11 can generate a transmission symbol by performing IFFT on the data symbol multiplied by the ZCZ code. The concrete procedure of generating the transmission symbol may be the same as that of step S110 of FIG. 2 described above. Here, the transmission symbol may be generated by performing an IFFT on all subcarriers.

The processing unit 11 can spread the transmission symbol on the time axis by the length of the ZCZ code and can transmit the spread transmission symbol. Here, the concrete spreading process of the transmission symbol may be the same as the step S120 of FIG. 2 described above, and the specific process of transmitting the spread transmission symbol may be the same as the step S130 of FIG. 2 described above.

Meanwhile, the processing unit 11 may include a processor and a memory. A processor may be a general purpose processor (e.g., a central processing unit (CPU), etc.) or a dedicated processor for performing a data transfer method. The memory may store program code for performing the data transfer method. That is, the processor can read the program code stored in the memory, and can perform each step of the data transmission method based on the read program code.

The storage unit 12 may store information stored in the processing unit and stored information. For example, the storage unit 12 may transmit a data symbol, a ZCZ code, a transmission symbol, a spread transmission symbol, and the like.

According to the uplink data transmission and reception method and apparatus according to the embodiment of the present invention described above, due to the strong characteristics of the synchronization error of the ZCZ code time-spread OFDMA, It is possible to maximize the spatial diversity gain through the cooperative base station system because no inter-terminal interference occurs. In addition, since the base station does not have to measure the distance to the terminal necessary for time synchronization every time, unnecessary power consumption can be prevented.

Next, a comparison between the performance of the uplink data transmission / reception method according to an embodiment of the present invention and the performance of the conventional uplink data transmission / reception method will be described. The experimental values used for the performance comparison are shown in Table 1 below.

In order to compare the performance of the uplink data transmission / reception method according to an embodiment of the present invention, the method is compared with a sparse SC-FDMA (single-carrier frequency division multiple access) scheme having strong characteristics for the time synchronization error between the uplinks. The sparse SC-FDMA scheme uses a structure in which a plurality of mobile stations share the entire subcarrier. At this time, data is not transmitted through subcarriers adjacent to subcarriers of other terminals in order to have strong characteristics against interference due to time error even if there is a time error between the terminals. However, it takes half the bandwidth loss. The method for transmitting / receiving uplink data according to an embodiment of the present invention also satisfies the same condition for the data rate because there are half the bandwidth loss since a total of eight terminals use a ZCZ code of length 16. It is assumed that the signal of each terminal reaches an equal distribution within the range of [0 T _s / 2] when the OFDM symbol interval is T _s .

FIG. 7 is a graph illustrating performance of the uplink data transmission / reception method and the sparse SC-FDMA scheme according to an embodiment of the present invention.

Referring to FIG. 7, it can be seen that the performance of the sparse SC-FDMA scheme using two base stations has improved performance over the sparse SC-FDMA scheme using only one base station due to the diversity gain. However, the sparse SC-FDMA scheme using two base stations has a performance difference as the E _b / N ₀ increases as compared with the sparse SC-FDMA scheme in which there is no time error between the UEs despite the strong characteristic of the time synchronization error . On the other hand, the uplink data transmission / reception method according to an embodiment of the present invention has almost the same performance as that of the sparse SC-FDMA scheme in which there is no time synchronization error between the UEs Able to know.

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 as defined in the appended claims. It will be possible.

10:
20:
30: Third terminal
100: first base station
200: Second base station

Claims (13)

A method for uplink data transmission to a cooperative base station performed in a terminal,
Multiplying a data symbol by a zero correlation zone (ZCZ) code;
Performing inverse fast fourier transform (IFFT) on the data symbols multiplied by the ZCZ code to generate transmission symbols;
Spreading the transmission symbol on a time axis by a length of the ZCZ code; And
And transmitting the spread transmission symbol. The method according to claim 1,
Wherein the data symbol multiplied by the ZCZ code is generated by multiplying all the subcarriers by the same ZCZ code. The method according to claim 1,
Wherein the ZCZ code has a zero correlation within a delay range for one chip. The method according to claim 1,
Wherein the length of the ZCZ code is a number of consecutive orthogonal frequency division multiplexing (OFDM) symbols to be transmitted by the mobile station. The method according to claim 1,
Wherein the transmission symbol is generated by performing the IFFT on all subcarriers. A method for receiving uplink data performed at a cooperative base station,
Receiving a signal;
Detecting a received symbol by performing inverse spreading on the signal based on a zero correlation zone (ZCZ) code;
Performing a fast fourier transform (FFT) on the received symbol; And
And detecting a data symbol from the FFT performed received symbol. The method of claim 6,
Wherein the signal is a signal spread on a time axis by a length of the ZCZ code. The method of claim 6,
Wherein the ZCZ code has a zero correlation within a delay range for one chip. A terminal for transmitting uplink data to a cooperative base station,
A data symbol is multiplied by a zero correlation zone (ZCZ) code, and an inverse fast fourier transform (IFFT) is performed on the data symbol multiplied by the ZCZ code, A processing unit for spreading the transmission symbol on the time axis by the length of the ZCZ code and transmitting the spread transmission symbol; And
And a storage unit for storing information stored in the processing unit and information to be stored. The method of claim 9,
Wherein the data symbols multiplied by the ZCZ code are generated by multiplying all the subcarriers by the same ZCZ code. The method of claim 9,
Wherein the ZCZ code has a zero correlation within a delay range for one chip. The method of claim 9,
Wherein the length of the ZCZ code is a number of consecutive orthogonal frequency division multiplexing (OFDM) symbols to be transmitted by the terminal. The method of claim 9,
Wherein the transmission symbol is generated by performing the IFFT on all subcarriers.

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