KR101631178B1 - Transmitter, reciever for relayed telecommunication and relayed telecommunication system using isotropic orthogonal transform algorithm prototype and offset quadrature amplitude modultation - Google Patents

Abstract

The present invention relates to a transmitter, a receiver, and a system for relay communications using an isotropic orthogonal transform algorithm prototype and an offset quadrature amplitude modulation. The system for relay communications comprises: a source node for transmitting a real component of a first OQAM symbol carried on a first subcarrier in a first cycle and transmitting an imaginary component of a first OAQM symbol carried on the first subcarrier in the next cycle of the first cycle; a relay node for demodulating a signal received from the source node in a second cycle and forwarding the demodulated signal in the next cycle of the second cycle; and a receiving node for demodulating the signal, which is transmitted from the source node and received in a third cycle, and the signal, which is forwarded from the relay node and received in the next cycle of the third cycle, into one OQAM symbol. The system of the present invention can reduce interference between the signal, which is forwarded through the relay node and transmitted to a destination node, and the signal, which is directly transmitted from the source node to the destination node, and improve communication quality in the relay communications.

Description

TECHNICAL FIELD The present invention relates to a transmitter, a receiver, and a relay communication system for relay communication using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation, and a transmitter, a receiver, and a relay communication system using offset quadrature amplitude modulation.

The present invention relates to a transmitter, a receiver and a communication system for relay communication using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation, and more particularly to a transmitter, a receiver and a communication system using offset orthogonal transformation algorithm prototype, Receiver and communication system for relay communication using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation to improve the quality of relay communication by using the immunity.

The decode and forward (DF) cooperative communication system, which has been recently actively researched, has advantages in terms of error probability due to the diversity gain and the error correction function of the DF relay. However, the DF repeater has a limitation of delaying a signal by a symbol period for the modulation / demodulation process. At this time, there is a problem that signals received from the source and the repeater at the destination act as interference with each other, causing performance deterioration or reducing the transmission rate.

Meanwhile, an Orthogonal Frequency Division Multiplexing (OFDM) system adopts a protection interval such as a Cyclic Prefix (CP) to provide a strong immunity from inter-symbol interference and inter-carrier interference by a multipath channel . However, insertion of a guard interval causes a problem of causing a decrease in effective transmission power and transmission efficiency. In this regard, an OFDM / Offset Quadrature Amplitude Modulation (OQAM) system using an isotropic orthogonal transform algorithm (IOTA) prototype is proposed as an alternative to an OFDM system using CP, . The OFDM / OQAM system uses an IOTA filter that maintains orthogonality in the time domain and frequency domain and has a characteristic that the energy dispersion is concentrated at the center of the pulse. The IOTA prototype has the advantage of improving the effective transmission power and transmission efficiency by replacing the guard interval insertion of the existing system.

Korean Patent Laid-Open No. 10-2005-0105224 (published on November 3, 2005, entitled "Wireless Data Transmission Method and Signals, System, Transmitter and Receiver, Claim 1)".

The present invention relates to a method and an apparatus for suppressing interference between a signal transmitted to a destination node forwarded through a relay node and a signal directly transmitted to a destination node from a signal transmitted to a destination node using the immunity to interference between adjacent symbols and carriers of an isotropic satellite orthogonal transformation algorithm prototype And orthogonal transformation algorithm prototype for reducing communication quality and improving communication quality, and transmitter, receiver and communication system for relay communication using offset quadrature amplitude modulation.

The relay communication system using the isotropic satellite orthogonal transformation algorithm prototype and the offset quadrature amplitude modulation according to an aspect of the present invention includes an OQAM symbol and an imaginary component representing a real component of a QAM symbol included in each subcarrier of one cycle of OFDM symbols A first node for transmitting a signal modulated with at least one of the OQAM symbols through an IOTA filter in one cycle, a relay node for demodulating a signal received from the source node in a first cycle, and forwarding the signal in the next cycle of the first cycle And a receiving node for recovering one QAM symbol from the signal transmitted from the source node received in the second period and the signal forwarded from the relay node received in the next period of the second period.

Preferably, the signals carried on adjacent subcarriers of mutually adjacent periods modulated through the IOTA filter have orthogonal phase characteristics.

Preferably, the OQAM symbol representing the real number component of the QAM symbol and the OQAM symbol representing the imaginary number component are modulated through the IOTA filter and have orthogonal phase characteristics.

Preferably, the receiving node includes an OQAM symbol indicating at least one of a real number component and an imaginary number component of a QAM symbol held in a subcarrier of an OFDM symbol in at least one of a forwarded signal from the relay node and a signal transmitted from the source node, Is demodulated through an IOTA filter.

Preferably, when the receiving node indicates a real component of an OAM symbol carried by one subcarrier, the OQAM symbol demodulated in the forwarded signal from the relay node indicates the real component of the signal transmitted from the source node, If the OQAM symbol representing the imaginary component of the OAM symbol is demodulated and the OQAM symbol demodulated in the signal forwarded from the relay node by the receiving node indicates the imaginary component of the OAM symbol carried in one subcarrier, The OQAM symbol representing the real component of the OAM symbol carried on the subcarrier is demodulated.

Preferably, the receiving node combines OQAM symbols representing the demodulated real and imaginary components proportional to respective signal-to-noise ratios.

Preferably, the receiving node selects an OQAM symbol having a higher SNR from among the OQAM symbol received from the relay node and the OQAM symbol received from the source node, and combines OQAM symbols representing a real component and an imaginary component.

Preferably, the source node includes: a full-variable part for performing orthogonalization by phase change so that OQAM symbols extracted from QAM symbols included in adjacent subcarriers are orthogonal to each other; And an IOTA filter unit for performing pulse shaping by applying the IOTA shaping function to the multiplexed modulated signal.

Preferably, the transmitter comprises: a first serial-to-parallel converter for extracting an OAQM symbol in a QAM symbol placed in each subcarrier of the one-period OFDM symbol based on an input signal; And a first parallel-to-serial conversion unit for calculating a transmission signal based on the formatted signal.

Preferably, the receiving node includes an IOTA orthogonal filter unit for calculating an orthogonality of a phase space by applying a complex conjugate of an IOTA shaping function to a received signal divided for each subcarrier, a Fourier transform form An equalizer section for estimating and recovering an OQAM symbol transmitted from an approximation of the OQAM symbol, and a postmodulation section for extracting only a real component from the output of the equalizer section.

Preferably, the receiver comprises: a second serial-to-parallel converter for dividing the received signal by each subcarrier according to a frequency corresponding to a subcarrier and outputting the resultant signal to the IOTA orthogonal filter unit; And a second parallel-to-serial converter for outputting an OFDM symbol for each subcarrier.

Advantageously, the equalizer estimates an OQAM symbol by equalizing an approximation of the OQAM symbol using a zero forcing technique.

Preferably, the relay node includes: a full-variable part for performing orthogonalization by phase change so that OQAM symbols extracted from QAM symbols included in adjacent subcarriers are orthogonal to each other; And an IOTA filter unit that receives the multiplexed modulated signal and performs pulse shaping by applying an IOTA shaping function, and a transmitter including an IOTA filter unit for each subcarrier, An IOTA orthogonal filter unit for calculating an orthogonality on a phase space by applying a complex conjugate function of a shaping function, a Fourier transform form unit for calculating an approximate value of an OQAM symbol by applying a Fourier transform to the orthogonal phase on the phase space, An equalizer section for estimating and recovering the transmitted OQAM symbol, And a post-modulation unit for extracting only a real component from the output of the negative.

According to the present invention, it is possible to improve the transmission rate reduction problem of the cooperative communication model using the existing DF repeater, to improve the transmission power and transmission band loss due to the guard interval of the existing OFDM system, and to improve the diversity gain by the MRC and SC techniques Therefore, it is possible to reduce the interference between the signal transmitted through the relay node and the signal transmitted to the destination node and the signal transmitted directly from the transmitting node to the destination node in the relay communication, and the communication quality can be improved.

1 is a schematic diagram of a relay communication system for relay communication using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with an embodiment of the present invention.
Figure 2 is a block diagram of a transmitter for relay communications using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with another embodiment of the present invention.
3 is a block diagram of a receiver for relay communication using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with another embodiment of the present invention.

Hereinafter, a transmitter, a receiver, and a relay communication system for relay communication using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation according to the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

1 is a schematic diagram of a relay communication system for relay communication using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with an embodiment of the present invention. 1, the relay communication system according to the present invention may include a source node 10, a receiving node 20, and a relay node 30.

The source node 10 transmits a signal obtained by modulating at least one of an OQAM symbol representing a real number component of a QAM symbol included in each subcarrier of one period of OFDM symbols and an OQAM symbol representing an imaginary number through an IOTA filter in one cycle .

형태의 복소수 값으로 표현되나, IOTA-OFDM/OQAM 시스템은

와

로 나누어지는 실수 값으로 구성되는 OQAM 심벌을 전송한다. 이 때 m은 신호가 실리는 서브캐리어를 나타내며, n은 OFDM 심벌의 인덱스를 나타낸다. 즉,

는 n번재 OFDM 심벌의 m번째 서브캐리어에 변조되는 QAM 심벌을 나타내며, 이는 두 개의 실수 값으로 구성되는 OQAM 심벌로 표현될 수 있다.

는 QAM 심벌의 실수 성분을 나타낼 수 있으며,

는 QAM 심벌의 허수 성분을 나타낼 수 있다. 즉, IOTA-OFDM/OQAM 시스템에서는 복소수 값을 갖는 QAM 변조된 심볼 대신, 반 주기에 대하여 위상이 지연된 형태로 나타나며 실수 값을 갖는 OQAM 변조된 심볼을 이용할 수 있다. 이는 IOTA 프로토타입(Prototype)을 구성하는 정형(Pulse Shaping)함수가 실수 값에 대해 유효한 가우시안 함수를 직교화하는 방법으로 만들어지기 때문이다. 이러한 IOTA 프로토타입은 시간 및 주파수 영역에서 에너지의 분산이 펄스의 중앙에 집중된 특징을 가지며, 각각의 변조 심벌에 대해 강한 직교성을 보장하는 특징이 있는 있다. 이하 수학식 1이 IOTA 프로토타입의 정의를 나타내고, IOTA 프로토타입이 직교성을 유지하는 조건이 수학식 2에 의해 주어질 수 있다.The QAM symbols transmitted by the existing OFDM system are

IOTA-OFDM / OQAM system is represented by a complex value of the form

Wow

And an OQAM symbol composed of a real number value divided by the transmission power. Here, m denotes a subcarrier on which a signal is carried, and n denotes an index of an OFDM symbol. In other words,

Denotes a QAM symbol modulated on the m-th subcarrier of the n-th OFDM symbol, which can be represented by an OQAM symbol composed of two real values.

Can represent the real component of the QAM symbol,

May represent the imaginary component of the QAM symbol. That is, in the IOTA-OFDM / OQAM system, instead of a QAM modulated symbol having a complex value, an OQAM-modulated symbol having a phase value delayed with respect to a half period and having a real value can be used. This is because the pulse shaping function of the IOTA prototype is made by orthogonalizing the Gaussian functions valid for real values. These IOTA prototypes are characterized in that the variance of energy in the time and frequency domains is centralized at the center of the pulse, with the feature of ensuring strong orthogonality for each modulation symbol. Equation (1) represents the definition of the IOTA prototype, and the condition that the IOTA prototype maintains orthogonality can be given by Equation (2).

As described above, the energy dispersion of the IOTA prototype is concentrated at the center of the function, and has the property of ensuring the orthogonality between the subcarriers and the subcarriers in the time and frequency domains. Therefore, the signals carried on the subcarriers adjacent to each other in the cycles adjacent to each other modulated through the IOTA filter may have orthogonal phase characteristics. In addition, the OQAM symbol representing the real number component of the QAM symbol and the OQAM symbol representing the imaginary number component may be orthogonal to each other in the signal modulated through the IOTA filter.

는 이웃한 심벌이 서로 직교하는 위상 성분으로 구성되도록 하며,

는 역 푸리에 변환(Inverse Fast Fourier Transform, IFFT)의 표현 방식에 따른 다중화 변조 기법을 나타내고,

와

는 각각

와

에 대한 IOTA 정형함수를 의미한다. 이 때, 송신 노드(10)가 송신하는 신호 s(t)는 다음의 수학식 3에 의하여 정의될 수 있다.In Equations (1) and (2)

The adjacent symbols are configured to be orthogonal to each other,

Shows a multiplexing modulation scheme according to a representation scheme of Inverse Fast Fourier Transform (IFFT)

Wow

Respectively

Wow

IOTA < / RTI > At this time, the signal s (t) transmitted by the transmitting node 10 can be defined by the following equation (3).

로 같게 될 수 있다.At this time, the transmission signal s (t) is pulse-shaped and multiplex-modulates each of the OQAM symbols included in the m-th subcarriers for the total M subcarriers constituting the n-th transmission symbol, that is, the OFDM symbol, using the IOTA function. Since the IOTA function is isotropic in time and frequency domain, the symbol period and sub-carrier band v ₀

≪ / RTI >

Figure 2 is a block diagram of a transmitter for relay communication using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with another embodiment of the present invention. 2, the transmitter includes a first serial-to-parallel converter 110, a first and second inverter 120 and 130, an inverse Fourier transformer 140 and 150, an IOTA filter 160 and 170, And a parallel-to-serial conversion unit 180, and the source node 10 may include a transmitter.

에 의하여 표현될 수 있다.The pre-modulation units 120 and 130 perform orthogonalization by phase shifting so that the OQAM symbols extracted from QAM symbols included in adjacent subcarriers are orthogonal to each other. In this case, the I-side variable part 120 may be composed of a real side front side variable part 120 for performing orthogonalization on the real component of the QAM symbol and an imaginary room modulation part 130 for performing orthogonalization on the imaginary component of the QAM symbol This orthogonalization is expressed by Equations (1) and (3)

Lt; / RTI >

에 의하여 표현될 수 있다.The inverse Fourier transformers 140 and 150 include a first inverse Fourier transformer 140 for performing an inverse Fourier transform on a real component and a second inverse Fourier transformer 150 for performing an inverse Fourier transform on an imaginary component, And can perform multiplexing modulation by inverse Fourier transform upon receiving a signal subjected to orthogonalization. At this time, the multiplex modulation performed by the inverse Fourier transform units 140 and 150 is expressed by Equations (1) and

Lt; / RTI >

와

에 의하여 표현될 수 있다. 이 때, IOTA 필터부(160, 170)는

에 해당하는 펄스 정형화를 수행하는 제1 IOTA 필터부(160) 및

에 대한 펄스 정형화를 수행하는 제2 IOTA 필터부로 구성될 수 있다.The IOTA filter units 160 and 170 receive the multiplexed modulated signal and perform pulse shaping by applying the IOTA shaping function. The pulse shaping is performed using Equation 1 and Equation 3

Wow

Lt; / RTI > At this time, the IOTA filter units 160 and 170

A first IOTA filter unit 160 for performing pulse shaping corresponding to

And a second IOTA filter portion for performing pulse shaping for the second IOTA filter portion.

에 의하여 표현되는 OQAM 심벌을 각 서브캐리어에 대하여 추출한다.The first serial-to-parallel converter 110 extracts an OQAM symbol from a QAM symbol included in each subcarrier of one cycle of OFDM symbols based on an input signal. That is, the first serial-to-parallel converter 110 converts an OFDM symbol into an equation

Lt; / RTI > is extracted for each subcarrier.

The first parallel-to-serial conversion unit 180 calculates a transmission signal based on the pulse-shaped signal for each subcarrier. That is, the first parallel-to-serial converter 180 performs the operation represented by the Σ symbol of the right side of the above Equation 3 to calculate s (t).

The receiving node 20 receives at least one of a real number component and an imaginary number component of a QAM symbol placed in a subcarrier of an OFDM symbol in at least one of a signal forwarded from the relay node 30 and a signal transmitted from the source node 10 OQAM symbols can be demodulated through an IOTA filter. That is, the receiving node 20 can demodulate the signals by performing the operations performed by the transmitter included in the source node 10 in the reverse order.

3 is a block diagram of a receiver for relay communication using an isotropic satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation in accordance with another embodiment of the present invention. 3, the receiver includes a second serial-parallel converter 210, IOTA orthogonal filter units 221 and 222, Fourier transformers 231 and 232, equalizer units 241 and 242, 252, 253, and 254 and a second parallel-to-serial conversion unit 260. The receiving node 20 may include a receiver.

In this case, when the gain of the channel experienced by each subcarrier of the signal s (t) transmitted by the transmitter is h _{m, n} , and the thermal noise added to the receiver is n (t), the signal reception signal r t) can be expressed by the following equation (4).

Assuming that the channel experienced by each subcarrier is a quasi-steady state, the demodulation process of the IOTA prototype for the received signal r (t) and the equalization process by the equalizer for recovering the OQAM symbol are expressed by the following equation (5) .

의 복소켤레함수

를 적용하여 위상 공간 상의 정사영을 산출할 수 있으며, 이는 송신부의 IOTA 필터부(160, 170)가 수행하는 작업을 역으로 수행하는 데에 해당할 수 있다.That is, the IOTA orthogonal filter units 221 and 222 add the IOTA orthogonal function to the received signals divided for each subcarrier,

Complex conjugate function of

May be applied to calculate the orthogonality in the phase space, which may correspond to the inverse operation performed by the IOTA filter units 160 and 170 of the transmitting unit.

에 의하여 표현된다.The Fourier transform units 231 and 232 can calculate an approximate value of an OQAM symbol by applying a Fourier transform to the orthogonality of the phase space. This is inversely performed by the inverse Fourier transform units 140 and 150 of the transmitter . In Equation (5), the approximate value of the OQAM symbol is

Lt; / RTI >

와 같이 표현될 수 있다. 즉, 제로 포싱 기법에 의하여 채널 이득에 의해 왜곡된 y_m,n 으로부터 전송되는 OQAM 심벌 a_m,n 을 추정하여 복수할 수 있다. 이 때

는 본래의 OQAM 심볼의 추정값을 나타내고,

은 이퀄라이저를 거친 잡음 성분을 나타낼 수 있다.The equalizer units 241 and 242 estimate and recover the OQAM symbol transmitted from the approximate value of the OQAM symbol. At this time, the equalizer units 241 and 242 can estimate the OQAM symbol by equalizing the approximate values of the OQAM symbols using a zero-forcing scheme. This zero-forcing technique is based on Equation (5)

Can be expressed as That is, the OQAM symbol a _{m, n} transmitted from y _{m, n} distorted by the channel gain by the zero-forcing technique can be estimated and multiplied. At this time

Represents the estimated value of the original OQAM symbol,

Can represent a noise component through the equalizer.

으로 표현되는 내재 간섭(Intrinsic Interference)으로서 IOTA 프로토타입의 직교성을 설명하는 모호성 함수(Ambiguity Funciton)의 특성에 의하여 0이 되어 소거될 수 있다. 따라서 제1 및 제 2 실수 후변조부(252, 253)가 이퀄라이저부(241, 242)의 출력에서 실수 성분만을 추출할 수 있으며, 이는 OFDM 심벌을 복원하는 데에 사용될 수 있다. The postmodulation units 251, 252, 253 and 254 extract only the real component from the output of the equalizer unit. In this case, the first and second imaginary post-modulation units 251 and 254 can extract imaginary components from the outputs of the equalizer units 241 and 242,

And can be cleared to 0 by the characteristic of the Ambiguity Funciton which explains the orthogonality of the IOTA prototype as an Intrinsic Interference. Therefore, the first and second post-real-time modulators 252 and 253 can extract only real components from the outputs of the equalizer units 241 and 242, which can be used to recover OFDM symbols.

The second serial-to-parallel converter 210 may divide the received signal r (t) for each subcarrier according to the frequency corresponding to the subcarrier, and output the divided signal to the IOTA orthogonal filter units 221 and 222. That is, it is possible to demodulate the received signal r (t) according to the frequency and demodulate by the IOTA prototype for each signal corresponding to each subcarrier.

The second parallel-to-serial converter 260 outputs the OFDM symbols for each subcarrier based on the real components extracted by the postmodulators 251, 252, 253, and 2454. That is, as described above, QAM symbols for each subcarrier can be restored from OQAM symbols estimated by a zero-forcing technique, and OFDM symbols transmitted by summing QAM symbols corresponding to subcarriers for one period can be restored have.

At this time, the IOTA orthophoric filter units 221 and 222, the Fourier transform units 231 and 232, the equalizer units 241 and 242, and the post-modulators 251 and 252, A first Fourier transformer 231, a first equalizer 241, first imaginary and real difference modulators 251 and 252 and a second IOTA orthogonal filter unit 222, a second Fourier transform A second equalizer unit 242, a second real number and imaginary part modulating unit 253 and 254, and the former demodulates the OQAM symbol corresponding to the real component of the QAM symbol, The OQAM symbol corresponding to the imaginary component of the QAM symbol can be demodulated.

In addition, the relay node 30 demodulates the signal received from the source node 10 in the first period and forwards the signal in the next period of the first period. That is, the relay node 30 may include all of the transmitter and the receiver, demodulate the received signal for one OFDM period, and perform forwarding for the next OFDM period. Therefore, the signal transmitted to the receiving node 20 through the relay node 30 is delayed by one period from the signal transmitted from the source node 10 directly to the receiving node 20.

At this time, if the OQAM symbol demodulated in the forwarded signal from the relay node 30 indicates the real component of the OAM symbol placed in one subcarrier, the signal transmitted from the source node 30 An OQAM symbol representing an imaginary component of an OAM symbol carried on a carrier is demodulated and an OQAM symbol demodulated in a signal forwarded from the relay node 30 by the receiving node 20 is an imaginary component of an OAM symbol placed in one subcarrier The OQAM symbol representing the real component of the OAM symbol placed in the subcarrier in the signal transmitted from the source node can be demodulated. 1, the OQAM symbol received from the source node 10 in the first period of the receiving node 20 represents an imaginary component, and the OQAM symbol received from the relay node 20 is a real component . On the other hand, in the second period, the OQAM symbols received from the source node 10 represent real components and the OQAM symbols received from the relay node 20 represent imaginary components. That is, when one of the OQAM symbols received by the receiving node 20 from the relay node and the OQAM symbol received from the source node 10 in the same period represents a real component, the other represents an imaginary component, So that the reception performance and the transmission rate can be improved as compared with the conventional DF Hill Ray cooperative communication.

Also, the receiving node 20 restores one QAM symbol from the signal transmitted from the source node 10 received in the second period and the signal forwarded from the relay node 30 received in the next period of the second period. As described above, the signal transmitted to the receiving node 20 through the relay node 30 is delayed by one period from the signal transmitted from the source node 10 directly to the receiving node 20, An OQAM symbol coinciding with an OQAM symbol representing an imaginary component of the mth subcarrier of the first symbol received from the source node 10 in the first period is transmitted from the relay node 30 in the second period It is possible to recover one QAM symbol by combining them. In this case, the QAM symbols reconstructed by combining the OQAM symbols and the OQAM symbols matched by the equalizer after demodulating the signals received in the 0th to 2 < th > periods by the IOTA prototype are expressed by Equation .

은 목적지에서 결합 기법을 통해 얻은 QAM 심볼을 나타내고, α는 결합 기법의 적용으로 인한 다이버시티 이득과 채널 이득을 나타내며, n'은 변복조 및 결합 과정을 통해 변형된 잡음 성분의 합을 나타낸다.In Equation (6)

Denotes a QAM symbol obtained through a combining technique at a destination, a denotes a diversity gain and a channel gain due to the application of the combining technique, and n 'denotes a sum of noise components modified through modulation and demodulation.

At this time, the receiving node 20 uses the at least one of the Maximum Ratio Combining (MRC) technique and the Selection Combining (SC) technique to transmit the symbol delayed by the relay node 30 to the source node 10, < / RTI > it is possible to obtain additional diversity gain. At this time, the receiving node 20 can combine the OQAM symbols representing the real and imaginary components demodulated using the MRC scheme in proportion to the respective signal-to-noise ratios. The combination by the MRC technique can be expressed by the following equation (7).

및

는 각각 중계 노드(30)와 소스 노드(10)로부터 수신한

및

에 해당하는 OQAM 심벌이 복조 과정과 이퀄라이저부(241, 242)를 통과한 뒤의 신호대잡음비 합을 나타낸다. In Equation (7)

And

Are received from the relay node 30 and the source node 10, respectively

And

To-noise ratio after the demodulation process and the equalizer units 241 and 242 have passed.

Also, the receiving node 20 selects an OQAM symbol having a higher signal-to-noise ratio among the OQAM symbols received from the relay node 30 and the OQAM symbols received from the source node 10 using the SC scheme, Lt; RTI ID = 0.0 > OQAM < / RTI > The combination by the SC technique can be expressed by the following equation (8).

및

는 각각 중계 노드(30)와 소스 노드(10)로부터 수신한

및

에 해당하는 OQAM 심벌이 복조 과정과 이퀄라이저부(241, 242)를 통과한 뒤 두 심볼 중 큰 신호대잡음비 성분을 지닌 OQAM 심벌인

및

를 결합하여 얻는 신호대잡음를 나타낸다.In Equation (8)

And

Are received from the relay node 30 and the source node 10, respectively

And

And the OQAM symbol corresponding to the large signal-to-noise ratio component of the two symbols after passing through the demodulation process and the equalizer units 241 and 242

And

To-noise ratio.

In this case, the SNR components received from the source node 10 and the relay node 30 using the MRC scheme and the SC scheme can be expressed by the following Equation (9).

As described above, according to the present invention, it is possible to improve the transmission rate reduction problem of the cooperative communication model using the existing DF repeater, to improve transmission power and transmission band loss due to the guard interval of the existing OFDM system, The reception performance can be improved by the diversity gain and interference between the signal transmitted to the destination node forwarded through the relay node and the signal directly transmitted from the transmitting node to the destination node in the relay communication can be reduced, .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill 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 by the appended claims. I will understand. Accordingly, the technical scope of the present invention should be defined by the following claims.

10: source node 20: receiving node
30; Relay node 110: first serial-to-
120: real number front panel 130: imaginary front panel
140: first inverse Fourier transform unit 150: second inverse Fourier transform unit
160: first IOTA filter unit 170: second IOTA filter unit
180: first parallel-to-serial conversion unit 210: second parallel-to-
221: first IOTA normal projection filter unit 222: second IOTA normal projection filter unit
231: first Fourier transform unit 232: second Fourier transform unit
241: first equalizer section 242: second equalizer section
251: first imaginary post-modulation unit 252: first real post-modulation unit
253: second post-error modulating unit 254: second post-imaginary modulating unit
260: a second parallel-to-serial converter

Claims (21)

A source node for transmitting, in one cycle, a signal modulated with at least one of an OQAM symbol representing a real number component of a QAM symbol and an OQAM symbol representing an imaginary number contained in each subcarrier of an OFDM symbol for one cycle;
A relay node for demodulating a signal received from the source node in a first cycle and forwarding the signal in a next cycle of the first cycle; And
And a receiving node for recovering one QAM symbol from the signal transmitted from the source node received in the second period and the signal forwarded from the relay node received in the next period of the second period,
If the OQAM symbol to be demodulated in the forwarded signal from the relay node indicates the real component of the OAM symbol carried in one subcarrier, the receiving node may calculate the imaginary number of the OAM symbol carried in the subcarrier in the signal transmitted from the source node The OQAM symbol representing the component is demodulated,
If the OQAM symbol to be demodulated in the signal forwarded from the relay node indicates an imaginary component of an OQAM symbol carried in one subcarrier, then OQAM indicating the real component of the OQAM symbol carried in the subcarrier in the signal transmitted from the source node, isotropic orthogonal transform algorithm satellite prototype, and offset the relay communication system using a quadrature amplitude modulation, it characterized in that the symbol is being demodulated.
The method according to claim 1,
Wherein the signals carried on the subcarriers adjacent to each other and modulated through the IOTA filter have phase characteristics orthogonal to each other, wherein the signals are orthogonal to each other, and the orthogonal transformation algorithm prototype and offset quadrature amplitude modulation are used.
The method according to claim 1,
An orthogonal orthogonal transformation algorithm prototype orthogonal to the orthogonal transformation algorithm and an offset quadrature amplitude modulation, characterized in that an OQAM symbol representing a real component of the QAM symbol and an OQAM symbol representing an imaginary component are modulated through the IOTA filter, A relay communication system to be used.
The method according to claim 1,
The receiving node transmits an OQAM symbol representing at least one of a real number component and an imaginary number component of a QAM symbol placed in a subcarrier of an OFDM symbol in at least one of a forwarded signal from the relay node and a signal transmitted from the source node to an IOTA filter Demodulating the orthogonal transformation algorithm based on the orthogonal orthogonal transformation algorithm.
delete The method according to claim 1,
Wherein the receiving node combines OQAM symbols representing the demodulated real and imaginary components in proportion to respective signal-to-noise ratios, and wherein the receiving node combines the OQAM symbols representing the real and imaginary components demodulated in proportion to respective signal-to-noise ratios.
The method according to claim 1,
Wherein the receiving node selects an OQAM symbol having a higher SNR among the OQAM symbols received from the relay node and the OQAM symbols received from the source node and combines OQAM symbols representing a real component and an imaginary component, A relay communication system using satellite orthogonal transformation algorithm prototype and offset quadrature amplitude modulation.
The method according to claim 1,
The source node comprising:
A full-order modulating unit for performing orthogonalization by phase shifting such that OQAM symbols extracted from QAM symbols included in adjacent subcarriers are orthogonal to each other;
An inverse Fourier transform unit that receives the orthogonalized signal and performs multiplexing modulation by inverse Fourier transform; And
And an IOTA filter unit that receives the multiplexed modulated signal and performs pulse shaping by applying an IOTA shaping function. The relay communication system of claim 1, further comprising: a transmitter including an orthogonal transform orthogonal transformation algorithm and offset quadrature amplitude modulation.
9. The method of claim 8,
The transmitter includes:
A first serial-to-parallel converter for extracting an OAQM symbol in a QAM symbol carried on each subcarrier of the OFDM symbol for one period based on an input signal; And
And a first parallel-to-serial conversion unit for calculating a transmission signal based on the pulse-shaped signal for each of the subcarriers.
The method according to claim 1,
The receiving node,
An IOTA orthogonal filter unit for calculating an orthogonality of a phase space by applying a complex conjugate of an IOTA shaping function to a received signal divided for each subcarrier;
A Fourier transform unit for calculating an approximate value of an OQAM symbol by applying a Fourier transform to the orthogonal projection on the phase space;
An equalizer for estimating and recovering an OQAM symbol transmitted from an approximation of the OQAM symbol; And
And a post-modulator for extracting only a real component from the output of the equalizer unit. The relay communication system using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation.
11. The method of claim 10,
The receiver includes:
A second serial-to-parallel converter for dividing the received signal for each subcarrier according to a frequency corresponding to the subcarrier and outputting the resultant signal to the IOTA orthopedic filter unit; And
And a second parallel-to-serial converter for outputting OFDM symbols for each subcarrier based on the real components extracted by the postmodulator. The orthogonal transformation algorithm and the relay parallel communication using offset quadrature amplitude modulation system.
11. The method of claim 10,
Wherein the equalizer unit estimates an OQAM symbol by equalizing an approximate value of the OQAM symbol using a zero forcing technique, wherein the equalizer unit estimates an OQAM symbol by approximating the OQAM symbol using a zero forcing technique.
The method according to claim 1,
The relay node comprising:
A full variable section for performing orthogonalization by phase change so that the OQAM symbols extracted from the QAM symbols included in adjacent subcarriers are orthogonal to each other,
An inverse Fourier transform unit that receives the orthogonalized signal and performs multiplexing modulation by inverse Fourier transform,
An IOTA filter unit for receiving the multiplexed modulated signal and performing pulse shaping by applying an IOTA shaping function; And
An IOTA orthogonal filter unit for calculating an orthogonality on a phase space by applying a complex conjugate of an IOTA shaping function to a received signal divided for each subcarrier,
A Fourier transform unit for calculating an approximate value of an OQAM symbol by applying a Fourier transform to the orthogonality of the phase space,
An equalizer section for estimating and recovering an OQAM symbol transmitted from an approximate value of the OQAM symbol,
And a post-modulator for extracting only a real component from the output of the equalizer unit. The relay communication system using an orthogonal orthogonal transformation algorithm prototype and offset quadrature amplitude modulation.
14. The method of claim 13,
The transmitter includes:
A first serial-to-parallel converter for extracting an OAQM symbol in a QAM symbol carried on each subcarrier of the OFDM symbol for one period based on an input signal; And
And a first parallel-to-serial conversion unit for calculating a transmission signal based on the pulse-shaped signal for each of the subcarriers.
14. The method of claim 13,
The receiver includes:
A second serial-to-parallel converter for dividing the received signal for each subcarrier according to a frequency corresponding to the subcarrier and outputting the resultant signal to the IOTA orthopedic filter unit; And
And a second parallel-to-serial converter for outputting OFDM symbols for each subcarrier based on the real components extracted by the postmodulator. The orthogonal transformation algorithm and the relay parallel communication using offset quadrature amplitude modulation system.
14. The method of claim 13,
Wherein the equalizer unit estimates an OQAM symbol by equalizing an approximate value of the OQAM symbol using a zero forcing technique, wherein the equalizer unit estimates an OQAM symbol by approximating the OQAM symbol using a zero forcing technique.




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