KR20090010582A - Full duplex relay device and method which can switch between relay mode and repeater mode - Google Patents

Abstract

The present invention relates to a full duplex relay device and method capable of switching between a relay mode and a relay mode, comprising: a transmission modem for generating a control signal for switching to a relay mode when an idle resource occurs while operating in a relay mode; A receiving switch for switching a signal from a receiving end to a transmitting switch according to a control signal for switching to the repeater mode, and a signal switched from the receiving switch to the transmitting end according to a control signal for switching to the repeater mode Including the transmitting switch to switch, there is an advantage that the relay can act as a relay in the idle period to effectively use the available resources of the increasing relay.

Description

Full duplex relay device and method that can switch between relay mode and repeater mode {APPARATUS AND METHOD FOR FULL DUPLEX RELAY CONVERTIBLE BETWEEN RELAY MODE AND REPEATER MODE}

The present invention relates to a multi-hop relay system, and more particularly, to a full duplex relay device and method capable of switching between relay mode and repeater mode.

The development of a new 4th generation mobile communication system is required to support a higher transmission rate than that provided by the 3rd generation mobile communication system and to expand the serviceable coverage. Research institutes and companies in many developed countries are already pushing ahead with technological developments for the next generation of standardization.

In the fourth generation mobile communication system operating in the high frequency region, the transmission rate and the service region are limited due to the high path loss. In order to solve this problem, a signal transmission method using multi-hop has been studied.

Signal transmission using the multi-hop requires one or more wireless repeaters or wireless relays to relay data between the transmitter and the receiver. Here, the wireless repeater simply amplifies the radio signal received from the transmitter and retransmits it to the receiver. Although the implementation is relatively simple, the noise is simultaneously amplified with the signal. In addition, since the repeater transmission signal is fed back to the repeater receiving antenna due to the nature of wireless, the amplifier may oscillate in an environment where it is difficult to secure sufficient isolation between the transmitting antenna and the receiving antenna, which may cause the repeater to malfunction. Recently, commercially available Interference Cancellation System (ICS) repeaters predict interference signals from the repeater outputs to the receiving antennas to prevent the oscillation of the repeaters by removing the predicted interference signals before the amplifier input.

Next, unlike the repeater, the relay basically demodulates and decodes the data received from the transmitter, and then encodes and modulates the data again to transmit to the receiver. The relay enables high-speed data communication by reducing path loss between radio links and enables communication even when the receiver is far from the transmitter or located in a shaded area. In general, the relay transmits and receives using different time or different frequency resources because of the interference of the transmitted signal to the received signal.

In a multi-hop relay system using the relay, communication between two nodes is performed through a serial radio link of a transmitter-relay, a relay-relay, and a relay-receiver.

1 illustrates a path in which one frame is transmitted in a multi-hop relay system using N-1 relays according to the prior art.

As shown, transmission of one frame is performed using N resource units, which may be configured on a time or frequency axis. In the following description, it is assumed that a unit resource is configured by a time slot for convenience of description. In slot 1, a transmitter transmits a frame to relay 1, in slot N-1, a relay N-2 transmits a frame received in a previous slot to relay N-1, and in slot N, a relay N -1) transmits the frame received in the previous slot to the receiver.

As such, the conventional relay cannot simultaneously transmit / receive using the same radio resource (full duplex relay) due to the interference of the transmitted signal on the received signal, and thus transmit and receive using different time or different frequency resources (half). Half duplex relay). This has a problem of causing a loss of transmission rate.

Meanwhile, if the interference problem can be solved, a full duplex relay capable of simultaneously transmitting and receiving using the same radio resource is possible, and in this case, the full duplex relay can use the same resource as the base station in downlink transmission. In case of uplink transmission, the same resource as the terminal may be used. Thus, the amount of radio resources (available resources) that the full duplex relay can use is increased compared to conventional relays that cannot use radio resources for reception.

2 illustrates available resources of a conventional relay and a full duplex relay in case of downlink transmission.

As shown, when the length of a transmission frame is T and the time at which a base station (BS) transmits data to a specific relay (RS) is T _R , in the case of a conventional relay, TT _R interval while the terminal: the other hand to push the data to the (mobile station MS) (5a) , full-duplex relay is the T _R Data may be transmitted to the terminal during the T interval including the interval (5b).

Thus, if the relay has enough data to transmit, the system capacity can be increased using the increased available resources of the full duplex relay. However, when the relay can transmit enough data to be transmitted only by the TT _R interval, the full duplex relay does not have an advantage in terms of efficiency of resource use because only an idle interval increases compared to the conventional relay.

3 illustrates idle resources of a full duplex relay when only a part of a frame is used as a transmission period in downlink transmission.

As shown, terminal a (MSa) represents one or more terminals that are directly serviced by the base station (BS), terminal b (MSb) represents one or more terminals that receive relay service through the relay (RS). Here, it can be seen that an idle section occurs because the full duplex relay transmits using only a partial section of the frame. In this case, although the transmission period of the relay is illustrated as an example of the reception period, the transmission period of the relay may be larger or smaller than the reception period.

Accordingly, an object of the present invention is to provide a full duplex relay device and method capable of switching between relay mode and repeater mode.

Another object of the present invention is to provide a full duplex relay device and method for simultaneous transmission and reception using the same radio resources by applying the interference cancellation technology, the transmission in the relay mode and the transmission in the relay mode using the remaining idle resources. Is in.

According to an exemplary embodiment of the present invention, a relay device capable of switching between a relay mode and a relay mode may switch to a relay mode when an idle resource occurs while operating in a relay mode. A transmission modem for generating a control signal, a reception switch for switching a signal from a receiver to a transmission switch according to a control signal for switching to the repeater mode, and a control signal for switching to the relay mode And the transmission switch for switching the signal switched from the reception switch to a transmitting end.

In order to achieve the above object, according to an embodiment of the present invention, a method of switching between a relay mode and a relay mode of a relay may include switching to a relay mode when an idle resource occurs while operating in a relay mode. And switching to the relay mode when the idle resource is exhausted while operating in the relay mode.

The present invention is capable of simultaneous transmission and reception using the same radio resources by applying the interference cancellation technology, by providing a full duplex relay device and method for transmitting in the relay mode using the remaining idle resources after the transmission in the relay mode, Simultaneous transmission and reception using radio resources increases the amount of radio resources that can be transmitted by the relay, thereby increasing the efficiency and flexibility of resource allocation. In particular, there is an advantage that the relay can act as a repeater in the idle period, thereby effectively using the available resources of the increasing relay. In other words, by using the idle resources of the relay to act as a relay, the base station or the signal transmitted by the terminal can be amplified and delivered to the terminal or the base station, respectively, thereby improving the link performance of the user who does not receive relay service, thereby improving the overall system capacity. There is an advantage that can contribute to the increase.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a full duplex relay apparatus and method capable of switching between a relay mode and a repeater mode according to the present invention will be described.

The present invention is capable of simultaneous transmission and reception using the same radio resources by applying the interference cancellation technology, and in order to provide a relay service using the idle resources of the relay, a full duplex for switching the relay to the relay mode when the relay is in an idle state A relay device and method are disclosed.

Figure 4 shows the device configuration of a full duplex relay capable of switching between relay mode and repeater mode according to the present invention.

As shown, the full duplex relay includes a radio frequency / intermediate frequency (RF / IF) receiver 401, an analog / digital converter (403), a reception modem (405), a data buffer (407), Transmission modem 409, Digital / Analog (D / A) converter 411, IF / RF (Intermediate Frequency / Radio Frequency) transmitter 413, interference signal controller 417, receive switch 423, transmit switch ( 425). Further, when the full duplex relay removes interference of not only the base band but also the RF / IF band when operating in the relay mode, or when removing the interference of the RF / IF band when operating in the relay mode, the full duplex relay Further comprises a coupler 415, a size converter 419, and a delay converter 421.

Referring to FIG. 4, first, the RF / IF receiving terminal 401 decreases an RF signal received through a receiving antenna and then outputs a baseband signal. In addition, the RF / IF receiving terminal 401 receives an RF / IF band interference signal estimate from the delay converter 421, and subsequently estimates the RF / IF band interference signal from an RF signal received through the receiving antenna. After the interference signal is removed, the RF signal from which the interference signal is removed is subjected to a frequency drop, and then a baseband signal is output.

The A / D converter 403 converts an analog signal from the RF / IF receiver 401 into a digital signal and outputs the digital signal.

The reception modem 405 demodulates and decodes the data from the signal from the A / D converter 403 and outputs the demodulated data. The receiving modem 405 also uses the signal from the A / D converter 403 and the output signal of the transmitting modem 409 to establish an interference channel between the receiving modem 405 and the transmitting modem 409. An estimated interference signal estimate is output to the interference signal controller 417. Thereafter, the receiving modem 405 receives a baseband interference signal estimate from the interference signal controller 417, and subsequently uses the baseband interference signal estimate in the signal from the A / D converter 403 to interfere. After the signal is removed, data is demodulated and decoded in the signal from which the interference signal is removed and output.

The data buffer 407 buffers data from the reception modem 405 and outputs the data to the transmission modem 409.

The transmission modem 409 encodes and modulates data from the data buffer 407 and outputs a transmission signal to the D / A converter 411, the reception modem 405, and the interference signal controller 417. In addition, the transmission modem 409 generates a transmission / reception switch control signal for switching between a relay mode and a relay mode to the reception switch 423 and the transmission switch 425. In other words, a control signal for operating in a relay mode is generated in a section having data to be transmitted, and a control signal for operating in a repeater mode is generated in an idle section in which there is no data to be transmitted. The transmission modem 409 may know an idle section at the time of scheduling or MAP formation, and thus may generate a transmission / reception switch control signal using the transmission modem 409.

The D / A converter 411 converts the digital signal from the transmission modem 409 into an analog signal and outputs the analog signal.

The IF / RF transmitter 413 increases the frequency of the signal from the D / A converter 411 and transmits the signal through the transmit antenna.

The coupler 415 couples the signal output from the IF / RF transmitter 413 to the magnitude converter 419.

The interference signal controller 417 generates the baseband interference signal estimate using the interference channel estimate from the receive modem 405 and the output signal of the transmit modem 409 and sends it to the receive modem 405. Output In addition, the interference signal controller 417 may also provide control signals for magnitude and delay conversion to the magnitude converter 419 and delay converter 421 to control interference cancellation of the RF / IF band for the corresponding path, respectively. have. Here, the control signal for magnitude and delay conversion is generated by using the interference channel estimate estimated by the reception modem 405 when operating in the relay mode.

The magnitude converter 419 converts the magnitude of the coupled signal from the coupler 415 using the magnitude conversion control signal from the interference signal controller 417, and outputs the magnitude to the delay converter 421.

The delay converter 421 converts the delay of the signal from the magnitude converter 419 using the delay conversion control signal from the interference signal controller 417 to generate an RF / IF band interference signal estimate, and Output to the RF / IF receiving end 401.

The receive switch 423 and the transmit switch 425 are controlled by a transmit / receive switch control signal for switching between the relay mode and the repeater mode generated by the transmit modem 409. When the transmit / receive switch control signal is a control signal for operating in a relay mode, the receive switch 423 switches the signal from the RF / IF receiving terminal 401 to the A / D converter 403 and outputs it. The transmission switch 425 switches and outputs the signal from the D / A converter 411 to the IF / RF transmitter 413. That is, to operate as a relay, the receive switch 423 and the transmit switch 425 are each closed to the position of a. On the other hand, when the transmit / receive switch control signal is a control signal that operates in the repeater mode, the receiving switch 423 switches the signal from the RF / IF receiving terminal 401 to the transmitting switch 425, The transmission switch 425 switches and outputs a signal from the reception switch 423 to the IF / RF transmission terminal 413. That is, in order to operate as a repeater, the receiving switch 423 and the transmitting switch 425 are closed to the position of b, and thus the output of the RF / IF receiver 410 is directly connected to the IF / RF transmitter 413.

Here, the operation of the interference signal controller 417 will be described in more detail.

First, s (k) transmits a signal transmitted by a transmitter through a specific frequency at a specific time k, H (k) transmits a channel from the transmitter to the reception modem 405 of the relay, and outputs the transmission modem 409 of the relay. X (k), and the interference channel from the transmission modem 409 to the reception modem 405 is called H _I (k). For convenience of explanation, it is assumed that channels H (k) and H _I (k) are constant at a given time and frequency, and if the channels are not constant, an equalizer technique or an orthogonal frequency division multiple access Multiplexing techniques such as Multiplexing (OFDM) can be used to pre-process the radio channel to be constant at a given time and frequency as described above. Then, the input signal y of the reception modem 405 can be expressed as Equation 1 below.

Here, n (k) represents the noise signal of the relay.

를 간섭 신호 제어기(417)에 제공하고, 상기 송신 모뎀(409)은 출력 신호 x(k)를 상기 간섭 신호 제어기(417)에 제공한다. 이때, 상기 간섭 신호 제어기(417)는 상기 두 입력 신호로부터 기저대역 간섭 신호 추정치

를 생성하여 상기 수신 모뎀(405)에 제공한다. 이때, 상기 수신 모뎀(405)은 하기 <수학식 2>를 이용하여 입력되는 수신 신호에서 간섭 신호를 제거할 수 있다.The receive modem 405 estimates the interference channel H _I (k) from the y (k).

Is provided to the interference signal controller 417, and the transmission modem 409 provides an output signal x (k) to the interference signal controller 417. At this time, the interference signal controller 417 estimates a baseband interference signal from the two input signals.

It generates and provides to the receiving modem 405. In this case, the reception modem 405 may remove the interference signal from the received signal by using Equation 2 below.

라면, 상기 수신 모뎀(405)은 상기 z(k)로부터 간섭 신호의 영향 없이 송신 신호 s(k)를 복원할 수 있다. OFDM 시스템의 경우 간섭 신호 추정 및 제거는 매 프레임 k에서 부반송파별로 수행할 수 있다.Here, z (k) represents a received signal after interference cancellation. If the estimate of the interference channel is correct, i.e.

If so, the reception modem 405 may recover the transmission signal s (k) from the z (k) without the influence of the interference signal. In the OFDM system, interference signal estimation and removal may be performed for each subcarrier in each frame k.

Here, the reception modem 405 may estimate the interference channel H _I (k) from the signal x (k) and the reception signal y (k) transmitted by the transmission modem 409 as shown in Equation 3 below. have.

Here, if the interference channel is estimated in a section in which the transmitter does not send a signal for more accurate interference channel estimation, the interference channel can be estimated without the influence of the signal H (k) s (k) from the transmitter. Here, a section in which the transmitter does not send a signal may use a section that occurs randomly during communication, and the protocol may be designed so that the transmitter does not send a signal for artificially estimating an interference channel during a specific section. Another method of increasing the accuracy of the interference channel estimation is possible by taking the average of the estimates of Equation 3 above for the interference channel over a certain time or frequency interval.

5 is a flowchart illustrating a method of switching between a relay mode and a relay mode in a full duplex relay according to the present invention.

Referring to FIG. 5, the full duplex relay operates in a relay mode in step 501 to transmit data received from a transmitter to a receiver, and checks whether an idle resource is generated in step 503. Here, whether the idle resource is generated may be determined when scheduling or MAP is formed through an internal transmission modem. When the idle resource does not occur, the full duplex relay returns to step 501 to maintain the relay mode and repeat the following steps.

On the other hand, when the idle resource is generated, the full duplex relay switches the mode to the repeater mode in step 505, operates in the repeater mode, transmits data received from the transmitter to the receiver, and proceeds to step 507. Check whether it is exhausted. When the idle resource is not exhausted, the full duplex relay returns to step 505 to maintain the repeater mode and repeat the following steps. On the other hand, when the idle resource is exhausted, the full duplex relay returns to step 501 to switch the mode to the relay mode and repeats the following steps.

6 illustrates idle resources of the full duplex relay according to the present invention when only a part of a frame is used as a transmission period in downlink transmission.

As shown in the figure, when only a partial section of a frame is used as a transmission section during downlink transmission, the full duplex relay according to the present invention operates in a relay mode in a section in which there is data to be transmitted, and when an idle section occurs, the corresponding idle Since the operation is switched to the repeater mode in the interval, it can be seen that the amount of idle resources is significantly reduced compared to FIG.

On the other hand, the switching mode between the relay mode and the repeater mode can be applied not only to the full duplex relay proposed in the present invention but also to the existing relay separating the transmission and reception intervals. That is, it is possible to operate by switching the relay to the relay mode during the interval except for the reception section and the transmission section of the relay.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a path in which one frame is transmitted in a multi-hop relay system using N-1 relays according to the prior art;

2 is a diagram illustrating available resources of a conventional relay and a full duplex relay in case of downlink transmission;

3 is a diagram illustrating idle resources of a full duplex relay when only a part of a frame is used as a transmission period in downlink transmission;

4 is a diagram illustrating a device configuration of a full duplex relay capable of switching between a relay mode and a repeater mode according to the present invention;

5 is a diagram illustrating a procedure of a method of switching between a relay mode and a relay mode in a full duplex relay according to the present invention; and

6 is a diagram illustrating idle resources of a full duplex relay according to the present invention when only a part of a frame is used as a transmission period in downlink transmission.

Claims (16)

In a relay device capable of switching between a relay mode and a repeater mode, A transmission modem for generating a control signal for switching to the relay mode when an idle resource occurs during operation in the relay mode; A receiving switch for switching a signal from a receiving end to a transmitting switch according to a control signal for switching to the repeater mode; And a transmitting switch for switching a signal switched from the receiving switch to a transmitting end according to a control signal for switching to the relay mode. The method of claim 1, The relay mode is a mode for transmitting the data received from the transmitter to the receiver after the demodulation, decoding and encoding and modulation again. The method of claim 1, The repeater mode is a mode for simply amplifying a signal received from the transmitter to transmit to the receiver. The method of claim 1, The relay device is characterized in that a full duplex relay device capable of transmitting and receiving at the same time using the same radio resources. The method of claim 1, wherein the transmission modem, And determining whether the idle resource is generated using a scheduling result. The method of claim 1, wherein the receiving end, Outputting a baseband signal after frequency dropping the signal received from the transmitter. The method of claim 1, wherein the transmitting end, A device which increases the frequency of an input signal and transmits it to the receiver. The method of claim 1, wherein the transmission modem, And transmitting / receiving switch control signals for switching to the relay mode when the idle resources are exhausted while operating in the relay mode. The method of claim 8, The receiving switch switches the signal from the receiving end to the receiving modem according to a control signal for switching to the relay mode, And the transmitting switch switches a signal from the transmitting modem to the transmitting end according to a control signal for switching to the relay mode. The method of claim 9, The receiving modem further demodulates and decodes data from the signal from the receiving end and outputs the data to a data buffer. And said transmission modem outputs a transmission signal by encoding and modulating data from a data buffer. The method of claim 10, And an interference signal controller for generating a baseband interference signal estimate using an interference channel estimate input from the receiving modem and an output signal of the transmitting modem, and outputting the baseband interference signal estimate to the receiving modem. The receiving modem estimates an interference channel between the receiving modem and the transmitting modem by using the signal from the receiving end and the output signal of the transmitting modem, outputs the estimated interference signal estimate to the interference signal controller, and then Subsequently, the baseband interference signal estimate inputted from the interference signal controller is used to remove the interference signal from the signal from the receiver, and to demodulate and decode the data from the signal from which the interference signal has been removed to output the data buffer. Characterized in that the device. The method of claim 11, A coupler for coupling and outputting a signal output from the transmitting end; A magnitude converter that adjusts and outputs a magnitude of the coupled signal according to a control signal of the interference signal controller; And a delay converter for adjusting the delay of the scaled signal according to a control signal of the interference signal controller to generate an interference signal estimate. The interference signal controller provides control signals for magnitude and delay conversion to the magnitude converter and delay converter, respectively, using the interference channel estimate; And the receiving end removes the interference from the signal received from the transmitter by using the generated interference signal estimate, and frequency-down the signal from which the interference is removed, and outputs a baseband signal. In a method of switching between a relay mode and a relay mode of a relay, Switching to the relay mode when an idle resource occurs while operating in the relay mode, Switching to the relay mode when the idle resource is exhausted while operating in the relay mode. The method of claim 13, The relay mode is a mode for demodulating and decoding data received from a transmitter, and then re-encoding and modulating the data to be transmitted to a receiver. The method of claim 13, The repeater mode is a mode for simply amplifying a signal received from the transmitter to transmit to the receiver. The method of claim 13, And the relay is a full duplex relay capable of transmitting and receiving at the same time using the same radio resource.

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