KR100800228B1 - Apparatus for transmitting signals with a reduced papr - Google Patents

Abstract

A signal transmission device for offering a reduced PAPR(Peak-to-Average Power Ratio) is provided to conduct retransmission by reconfiguring transmission sequence of a signal having a PAPR value more than a reference value as preventing transmission of the signal, thus a low-cost signal transmission device can be configured without causing performance deterioration. A distributor(108) distributes a transmission signal consisting of plural transmission data into the first and second distribution signals. A phase inversion unit(112) inverts a phase of the second distribution signal. If a PAPR value of the first distribution signal is more than a predetermined reference value in a predetermined time slot, an adder(116) adds up the first distribution signal and the phase-inverted second distribution signal. A transmitter(126) transmits the added signals.

Description

Signal Transmitter with Reduced PAP (APPARATUS FOR TRANSMITTING SIGNALS WITH A REDUCED PAPR)

1 is a diagram showing the structure of a signal transmission apparatus implemented in a base station according to an embodiment of the present invention;

2 is a flowchart illustrating a signal transmission method according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

106, 110: multiplexer 108: distributor

112: Phase Inverter 114: PAPR Calculator

116: summer 118: switch

120: ARQ check unit 122: retransmission controller

124: DAC

The present invention relates to a signal transmission apparatus and a signal transmission method for reducing the peak-to-average power ratio (PAPR) of a transmission signal in a communication system of a multiple access method.

The rapid increase in demand and interest in mobile communication has led to the development of multiple access digital data communication. Multiple access digital data communication is intended to allow multiple individual signals to be transmitted and received simultaneously via limited radio resources. In particular, a multi-access communication system capable of simultaneously transmitting signals of multiple channels using signals having orthogonal characteristics is widely used because it can greatly improve signal transmission speed.

When data is transmitted according to a multiple access scheme for simultaneously transmitting signals of multiple channels using the orthogonal characteristics of the signals, channel coding is performed on each data for transmission, and multiplexing of these channel coded data, that is, The signal is summed into one signal, converted into an analog signal, and the baseband analog signal is up-converted to a transmission frequency band to perform power amplification by a power amplifier and then transmitted through an antenna. As such, when summing a plurality of channel coded signals, an increase in power is generated in the summed signal. In particular, an increase in peak power is markedly increased compared to an increase in average power, and thus, PAPR is increased. . Although the probability of generating peak power signals is low, in order to deliver the transmitted signal to the receiver without distortion, even these peak power signals must be able to pass through the transmitter, thus enabling high capacity wireless devices such as high capacity wireless up-converters, Power amplifiers, filters, etc. are required, which leads to an increase in system cost. In particular, since the increase of the PAPR becomes larger in proportion to the increase in the number of channels, the problem becomes serious as the number of multiple access signals increases.

Therefore, there is a need for a signal transmission apparatus and a signal transmission method capable of reducing the PAPR of a transmission signal without causing a decrease in transmission performance in a multiple access communication system.

Accordingly, an object of the present invention is to provide a low capacity and low cost signal transmission apparatus and a signal transmission method capable of reducing PAPR of a transmission signal without causing a decrease in transmission performance in a communication system of a multiple access method.

According to one aspect of the invention, there is provided a signal transmission apparatus having a reduced PAPR. The apparatus of the present invention includes a divider for distributing a transmission signal composed of a plurality of transmission data into first and second divided signals, and a phase inverter for inverting the phase of the second divided signal. In addition, when the PAPR value of the first divided signal in a predetermined time interval is equal to or greater than a predetermined reference value, the adder includes a summer summating the first divided signal and the second divided signal inverted in phase, and the summed signal is added by the adder. And a signal transmitter for transmitting.

According to an embodiment of the present invention, when the PAPR value of the first divided signal is greater than or equal to a predetermined reference value in a predetermined time interval, the second divided signal is transmitted to the summer, or the second divided signal is blocked. A switch is further included.

According to an embodiment of the present invention, if the PAPR value of the first divided signal in a predetermined time interval is greater than or equal to a predetermined reference value, a retransmission controller for controlling retransmission of transmission data corresponding to the predetermined time interval is further included. .

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. However, in the following description, when there is a risk of unnecessarily obscuring the gist of the present invention, a detailed description of well-known functions and configurations will be omitted. In addition, it should be understood that the embodiments described below are intended to illustrate the present invention, but not to limit the present invention.

1 is a diagram showing the structure of a signal transmission apparatus implemented in a base station according to an embodiment of the present invention. As shown in FIG. 1, the signal transmission apparatus 100 includes traffic channel coding units 102a-102n for individually coding a plurality of traffic signals to be transmitted, and a control channel coding unit 104 for coding a control signal. do. The multiplexer 106 receives the channel coded signal from each of the traffic channel coding units 102a-102n, and the divider 108 receives the resulting signal processed by the multiplexer 106. Multiplexer 110 and phase inverter 112 each receive a signal distributed at divider 108. Phase inverter 112 inverts the phase of the received signal and transfers it to switch 118. The multiplexer 110 receives a channel coded signal from the control channel coding unit 104 in addition to the signal input from the divider 108, and the PAPR calculator 114 receives a result signal processed by the multiplexer 110. The signal input to the PAPR calculator 114 is transmitted to the summer 116 as it is. The switch 118 receives the control signal C1 determined according to the PAPR value calculated by the PAPR calculator 114, and the automatic repeat request (ARQ) checker 120 also calculates the PAPR calculator 114. The control signal C2 according to the PAPR value is received. The retransmission controller 122 receives the control signal C3 from the ARQ checker 120, and the control signal from the retransmission controller 122 is controlled by the control channel coding unit 104 and each traffic channel coding unit 102a-102n. Is delivered. Summer 116 receives signals from PAPR calculator 1114 and switch 118 and sums them. The digital-to-analog converter (DAC) 124 receives the signal processed by the summer 116, and the signal transmitter 126 receives the output signal from the digital-to-analog converter 124 and wirelessly transmits it.

Each traffic channel coding section 102a-102n receives each traffic data desired to be transmitted and performs channel coding for each. Such channel coding is made in a direction to allow a receiver to recognize whether an error has occurred and to perform self-correction of the error in consideration of occurrence of an error due to radio transmission between the transceivers. For example, the traffic channel coding units 102a to 102n may be implemented to perform Reed Solomon coding, convolutional coding, interleaving, and the like. In addition, the traffic channel coding units 102a to 102n perform channel coding as signals having orthogonal characteristics so as to identify each individual traffic data. For example, in the case of the CDMA scheme, frequency spreading using a spreading code having an orthogonal characteristic is included.

The control channel coding unit 104 performs channel coding on a control signal to be transmitted to the transmitter together with the traffic data. The control signal may include information about each traffic channel, synchronization information, receiver activation information, and the like. The control channel coding unit 104 performs encoding processing in preparation for the occurrence of an error with respect to the control signal similarly to the traffic channel coding units 102a to 102n. In addition, the control channel coding unit 104 performs channel coding as a signal having an orthogonal characteristic so that the control signal can be identified from each traffic data.

The multiplexer 106 receives the channel coded signals at each traffic channel coding section 102a-102n and sums the output signals from each of the traffic channel coding sections 102a-102n to perform multiplexing. In the conventional mobile communication system, the output signals from the traffic channel coding unit are multiplexed together with the output signals from the control channel coding unit, but according to the present invention, the traffic signals are first multiplexed before the multiplexing with the signal from the control channel coding unit 104. Multiplexing between the signals from the channel coding units 102a-102n is performed.

Splitter 108 receives one signal multiplexed at multiplexer 106 and distributes it into two signals. Divider 108 performs signal distribution such that the two divided signals maintain the same characteristics as the original signal.

The multiplexer 110 receives one of two signals distributed at the divider 108. The multiplexer 110 also receives the channel coded signals from the control channel coding section 104 as well as the signals from the divider 108 and sums these signals to perform multiplexing.

Phase inverter 112 receives the other of the two signals distributed at divider 108. Then, the phase of the received signal is inverted 180 °. As described later, when the PAPR value is greater than or equal to the reference value, the signal is canceled by summing the phase-inverted signal and the original signal.

The PAPR calculator 114 receives the multiplexed signal at the multiplexer 110 and calculates the magnitude of the PAPR signal of the corresponding signal. Then, the magnitude of the calculated signal is compared with a predetermined reference value, and when the comparison determines that the magnitude of the PAPR signal is greater than or equal to the reference value, the time interval of the signal is determined. Then, the PAPR calculator 114 generates the respective control signals C1 and C2 to control the switch 118 and the ARQ checker 120 in relation to the signal of the corresponding time period. Specifically, when it is determined that the calculated size of the PAPR signal is greater than or equal to the reference value, the PAPR calculator 114 outputs a control signal for turning on the signal of the corresponding time interval, and the NAK for the ARQ checker 120. Outputs a negative acknowledgment signal. Here, the NAK signal is a control signal informing that transmission of corresponding data is required because the PAPR size of the transmission signal exceeds a reference value and transmission is impossible. Meanwhile, the PAPR calculator 114 outputs the signal received from the multiplexer 110 as it is and delivers it to the summer 116.

The switch 118 is turned on / off in accordance with the control signal C1 from the PAPR calculator 114. As described above, when the control signal C1 input to the switch 118 determines that the PAPR size of the transmission signal is greater than or equal to the reference value by the PAPR calculator 114, the control signal C1 is used to turn on the switch 118 for the signal. Signal, otherwise, switch 118 is turned off. When the switch 118 is turned on, the phase inversion signal from the phase inverter 112 is transmitted to the summer 116 through the switch 118. When the switch 118 is in the off state, the phase inversion signal is blocked from affecting the transmission signal on the transmission path.

As described above, the ARQ checker 120 receives the NAK signal from the PAPR calculator 114 when the magnitude of the PAPR value of the signal is greater than or equal to the reference value. When the ARQ checker 120 receives the NAK signal, the ARQ checker 120 recognizes that transmission data of the corresponding time interval has been erased and retransmission is required accordingly. Then, the ARQ checker 120 checks the frame or sequence of the data in which the loss of data is known by the NAK signal, and then outputs the checked result.

Summer 116 receives signals from PAPR calculator 114 and, if switch 118 is on, receives signals sent from phase inverter 112 via switches and sums them. When the switch 118 is in the OFF state, no signal is transmitted via the switch 118, so the signal transmitted from the PAPR calculator 114 is bypassed.

The digital / analog converter 124 receives a signal from the multiplexer 116 and converts the received digital signal into an analog signal. The signal transmitter 126 receives the converted analog signal, performs frequency conversion, power amplification, and the like, and wirelessly transmits the signal. As described above, in a time interval in which the PAPR signal is greater than or equal to the reference value, as the phase-inverted signal transmitted through the switch 118 is summed with the transmission signal in the multiplexer 116, the signal transmitted by the signal transmission unit 126 may be reduced. The traffic signal is canceled.

The retransmission controller 122 receives a signal from the ARQ checker 120. That is, the retransmission controller 122 receives a control signal C3 about whether there is a signal that needs to be retransmitted from the ARQ checker 120, and if so, what data frame or sequence is required for the retransmission. The retransmission controller 122 then performs random processing on the transmission order of the data for which retransmission is required. This is to prevent reconstruction of a transmission signal having a high PAPR value again upon retransmission. Since the probability of occurrence when the PAPR value is above the reference value is considerably low, a transmission signal having a high PAPR value rarely occurs even after such random processing. The control signal generated in the retransmission controller is used for control of channel coding of data performed in the control channel coding unit and each traffic channel coding unit.

2 is a flowchart illustrating a signal transmission method according to an embodiment of the present invention.

First, channel coding is performed on a plurality of traffic signals and control signals, respectively (202). Perform multiplexing on the channel coded multiple traffic signals (204) and distribute the multiplexed signal into two signals (206). A transmission signal is generated by multiplexing one of the distribution result signals with the channel coded control signal (208), and then the PAPR value in that transmission signal is calculated and compared to a reference value (210).

If it is determined in step 210 that the PAPR value is greater than or equal to the reference value, the other one of the distribution result signals is phase inverted by 180 °, and the phase inverted signal is summed with the generated transmission signal (212) to add up. Wirelessly transmit the result (214). In addition, by determining the time interval of the signal is determined that the PAPR value is greater than the reference value to find the data required for retransmission (216), and then reconstruct the order of the retransmission of the data that needs to be retransmitted (218). Then, the process returns to step 202 to perform transmission processing of data requiring retransmission in the reconstructed order. On the other hand, if it is determined in step 210 that the PAPR value is less than the reference value, the transmission signal is wirelessly transmitted as it is (222), and the procedure ends.

Although the present disclosure has been described mainly with respect to signal transmission in a CDMA communication system, it should be understood that the present invention may be applied to a communication system of various multiple access methods in which a plurality of channel signals are added and transmitted.

According to the present invention, in a communication system of a multiple access method, transmission of signals having a PAPR value higher than a reference value is prevented, and retransmission is performed by reconfiguring the transmission order for such signals, thereby causing performance degradation due to signal loss. Without this, the configuration of the low capacity and therefore low cost signal transmission apparatus becomes possible.

Claims (5)

As a signal transmission device, A distributor for distributing a transmission signal composed of a plurality of transmission data into first and second distribution signals, A phase inverter for inverting the phase of the second distribution signal, A summer for adding up the first divided signal and the second divided signal inverted in phase when the PAPR value of the first divided signal is equal to or greater than a predetermined reference value in a predetermined time period; Signal transmitting unit for transmitting the signal summed by the summer Signal transmission device comprising a. The method of claim 1, And transmitting a second divided signal to the summer when the PAPR value of the first divided signal is equal to or greater than a predetermined reference value in a predetermined time interval, and otherwise, blocking the second divided signal. Signal transmission device. The method of claim 1, And a retransmission controller for controlling retransmission of transmission data corresponding to the predetermined time interval when the PAPR value of the first divided signal is greater than or equal to a predetermined reference value in a predetermined time interval. The method of claim 3, And a retransmission controller randomly reconstructs the retransmission order of the transmission data corresponding to the predetermined time interval. The method of claim 1, And a multiplexer for summing a control signal and the first distributed signal.

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