KR20120055343A - Wireless transmission module - Google Patents

Abstract

PURPOSE: A wireless transmission module is provided to prevent distortion of a signal when data are transmitted by a high order modulation method. CONSTITUTION: A plurality of power amplifiers(430,440,450,460) amplify input data. The power amplifiers are connected each other in parallel. A control unit turns the power amplifiers on/off according to an MCS(Modulation and Coding Scheme) level for transmitting the data. Output of at least one power amplifier is summed wherein the power amplifier is turned on by the control unit.

Description

Wireless Transmission Module {WIRELESS TRANSMISSION MODULE}

The present invention relates to a wireless transmission module, and more particularly, power provided in a transmitter of a communication system to which an adaptive modulation and coding (AMC) scheme is applied. A transmission / reception module, which is configured to vary transmission linearity according to a modulation and coding scheme (MCS) level, and relates to a transmission module having optimal linearity according to a channel environment.

In the wireless communication system, a multiple access method for efficiently allocating a frequency band to a plurality of users is applied for efficient wireless communication. Such a multiple access scheme is a platform technology that is the basis of a wireless transmission technology for efficiently using limited frequency resources, and is determined according to an allocated frequency band, the number of users, a transmission rate, mobility, a cell structure, and a wireless environment.

OFDM-FDMA (OFDMA), which is one of the wireless access schemes using the multiple access scheme, is suitable for 4G macro / micro cellular infrastructure, and has no intra-cell interference, high frequency reuse efficiency, and excellent adaptive modulation. In addition, the OFDMA method is suitable for a large number of subcarriers, and thus is effectively applied to a wireless communication system having a large area cell having a relatively large time delay spread.

In general, in a broadband wireless communication system capable of high-speed packet data transmission by using the OFDMA scheme, a base station uses modulation to coding (MCS) of bursts allocated to a frame by using carrier to interference & noise ratio (CINR) information measured from a terminal. Adaptive Modulation and Coding (hereinafter, referred to as 'AMC') is applied.

Meanwhile, as demand for terminals and communication devices using a broadband wireless communication system increases, there is a demand for a communication device that is compact, light in weight, low power consumption, and can be used for a long time. There is a need for techniques to improve the quality of the system. A communication device such as a wired or wireless telephone or a mobile phone includes a power amplifier module (PAM) that amplifies power in the transmitter as a wireless transmission module. In particular, the power amplification module embedded in a mobile terminal such as a mobile phone is a component that amplifies a high frequency signal output from the mobile terminal and transmits it to a base station. It is a key component that determines the talk time and call quality of the mobile terminal.

When transmitting data in a higher order modulation scheme of 64QAM or more in a mobile terminal, a wireless transmission module having high linearity is required. This means that in case of data transmission using a higher-order modulation scheme of 64QAM or more, a signal to noise ratio (SNR) of at least a certain level must be maintained, which means that high linearity is required. The demand for high linearity increases the amount of current consumption, which leads to a decrease in the transmission efficiency of the communication modem, which results in a decrease in the service time of the communication modem. Therefore, even in the case of data transmission using a higher-order modulation method, while supporting linearity so that signal distortion does not occur, current research has been conducted on a highly efficient wireless transmission module that does not significantly increase the consumption in terms of current consumption.

The present invention provides a new wireless transmission module that supports high transmission power so that signal distortion does not occur even when data is transmitted in a higher-order modulation scheme, but the total current consumption is not different from that of a conventional wireless transmission module. Its purpose is to provide a wireless transmission module configured to be variable.

Therefore, the wireless transmission module according to the present invention relates to a wireless transmission module that varies linearity in signal transmission according to a modulation and coding scheme (MCS) level of a signal received by a wireless terminal, and parallelly amplifies and outputs input data. A plurality of power amplifiers (PAs) connected to each other; And a controller configured to control power on / off of each of the plurality of power amplifiers according to a modulation and coding scheme (MCS) level for transmitting the data. The sum of the outputs of at least one power amplifier turned on by the power is output.

Herein, the controller controls the power of each of the plurality of power amplifiers such that more power amplifiers are powered on than in the case of transmitting the data in the higher-order modulation scheme according to the MCS level. It is characterized in that the power (On) / off (Off).

The control unit may include at least one switching element for turning on / off power of each of the plurality of power amplifiers according to the MCS level.

The wireless transmission module according to the present invention supports linearity even in the case of higher order modulation. In addition, considering that a wireless transmission module that supports linearity even when transmitting data of a higher-order modulation method is configured to support high transmission power regardless of the modulation method, the wireless transmission module according to the present invention has a total current consumption compared thereto. It is small and more efficient.

Accordingly, the present invention prevents signal distortion even when data is transmitted in a higher-order modulation scheme, and contributes to implementing an optimal communication system suitable for peak power to average power ratio (PAR) of a transmission signal.

1 is a diagram illustrating an embodiment of an AMC communication system configuration to which the present invention is applied.
2 is a diagram illustrating a transmitter to which the present invention is applied.
3 is a diagram schematically illustrating a configuration of a wireless transmission module according to the present invention.
4 is a diagram illustrating a wireless transmission module configuration according to an embodiment of the present invention.
5 is a diagram illustrating a state in which a wireless transmission module according to the present invention supports linearity according to a modulation scheme.

The following detailed description is only illustrative, and merely illustrates embodiments of the present invention. In addition, the principles and concepts of the present invention are provided for the purpose of explanation and most useful.

The AMC scheme supports a plurality of modulation schemes and a plurality of coding rates according to a modulation and coding scheme (MCS) level. The combination of coding rate and modulation scheme is called a Modulation and Coding Scheme (MCS), and a plurality of MCS levels may be defined from level 1 to level N according to the number of MCSs.

Table 1 below shows the MCS level setting according to the standards of High-Speed Downlink Packet Access (HSDPA) and 3G Long Term Evolution (LTE).

MCS Level Data rate (Kbps) Per frame
Number of bits Code rate Modulation method Transfer rate
(15 codes) One 180 1800 1/3 QPSK 2.7 Mbps 2 360 3600 1/2 QPSK 5.4 Mbps 3 536 5360 1/2 16QAM 8.0 Mbps 4 720 7200 1/2 64QAM 10.8 Mbps

As shown in Table 1, the MCS level is higher from MCS level 1 (QPSK, turbo code 1/3) to MCS level 4 (64 QAM, turbo code 1/2). Can be set to be assigned. The higher order modulation method and the coding rate have the advantage of better data rate than the lower order modulation method and the coding rate, and the lower order modulation method and the coding rate have the advantage of low error rate. Therefore, when the channel condition is good, a higher order modulation scheme and a higher coding rate (eg, MCS level 4) may be selected, and as the channel state worsens, a lower order modulation scheme and a coding rate (eg, MCS level 1) may be selected.

Here, the channel state may be estimated according to a signal to noise ratio (SNR), and the MCS level corresponding to the preset SNR range may be applied. For example, it is possible to set MCS level 1 to be selected when the SNR range is -10 dB to -5 dB, and to set MCS level 4 when it is +10 dB or more. Criteria for setting the MCS level may be variously set according to each system.

1 is a diagram illustrating an embodiment of an AMC communication system configuration to which the present invention is applied.

The receiver 200 may be composed of a receiving antenna 210, a wireless receiving module 220, a demodulator 230, a channel deinterleaver 240, and a decoder 250. Operation of each component is as follows.

The wireless receiving module 220 filters and amplifies the signal received through the receiving antenna 210, and the demodulator 230 demodulates the received signal output through the wireless receiving module 220, and dechannels the channel. The channel 240 deinterleaves the demodulated received bit data, and the decoder 250 decodes the channel deinterleaved bit data and outputs the received data. The channel state estimator 260 estimates the channel state based on the RSSI / CINR of the received signal output through the wireless receiving module 220.

The transmitter 100 may include an MCS level selector 140, an encoder 110, a channel interleaver 120, a modulator 130, a wireless transmission module 150, and a transmission antenna 160. The operation is as follows.

The MCS level selector 140 selects the MCS level according to the channel state information estimated by the channel state estimator 260, and the encoder 110 codes the transmission data according to the MCS level selected by the MCS level selector 140. The channel interleaver 120 channel interleaves the coded transmission bit data according to the MCS level, and the modulator 130 modulates the channel interleaved transmission bit data according to the MCS level. The wireless transmission module 150 converts the modulated transmission data into an RF signal, amplifies it according to transmission power, and outputs it through the transmission antenna 160.

The MCS level selector 140 may be included in the transmitter 100 or may be included in the receiver 200. The modulator 130 and the demodulator 230 of the transmitter 100 and the receiver 200 may modulate and demodulate a signal in a QPSK, 16QAM, or 64QAM modulation scheme. The encoder 110 and the channel interleaver 120, the decoder 250, and the channel deinterleaver 240 may perform channel coding and channel decoding using turbo coding methods having coding rates 1/3 and 1/2. The MCS level selector 140 selects a higher order modulation method and a higher coding rate (eg, MCS level 4) when the channel condition is good, and selects a lower order modulation method and a coding rate (eg, MCS level 1) as the channel condition worsens. You can choose.

Accordingly, the transmission data is subjected to coding and interleaving according to the MCS level selected by the MCS level selector 140 and then similarly subjected to a modulation process according to the modulation technique selected by the MCS level selector 140 and then through the wireless transmission module 150. It is sent out.

The present invention relates to a wireless transmission module 150 applied to the transmitter of the AMC communication system, the appearance of the transmitter to which the present invention is applied is shown in FIG.

The wireless transmission module 150 according to the present invention is configured to receive an MCS level selection signal from the MCS level selector 140 and vary the transmission linearity according to the selected MCS level. In other words, when the MCS level selector 140 modulates the higher order modulation scheme according to the MCS level selected by the MCS level selector 140 to transmit data, the radio transmission module 150 may not cause distortion in the output signal. Perform the operation in the high linear mode of operation. In the case of transmitting data after being modulated by the lower order modulation method, the linear signal operation mode is performed because distortion is not generated in the output signal even in a relatively low linear operation region as compared with the higher order modulation method.

This operation may implement an optimized communication system that meets the peak power to average power ratio (PAR) of the transmission signal while supporting the minimum linearity in any case where the wireless transmission module 150 transmits data in a low order or high order modulation scheme. To be. In addition, in terms of current consumption, the efficiency is higher because the power consumption is small compared to a wireless transmission module that provides high linearity that should be used when transmitting data in a higher-order modulation scheme.

3 is a diagram schematically illustrating a configuration of a wireless transmission module according to the present invention, and may include a plurality of power amplifiers PAs 310-1, 2, n and a controller 300 connected in parallel. have. The wireless transmission module 150 receives an MCS level selection signal from the MCS level selector 140 and also receives modulated transmission data through the modulator 130.

The controller 300 is configured to perform a function of turning on / off power of the plurality of power amplifiers 310-1, 2, n connected in parallel, and in parallel according to the MCS level selection signal. Controls the number of power amplifiers for amplifying the transmission data among the plurality of power amplifiers 310-1, 2, n connected to each other. In addition, the outputs of the power amplifiers 310-1, 2, n performing the signal amplification operation under the control of the controller 300 are summed and output from the wireless transmission module 150.

More specifically, the controller 300 increases the number of power amplifiers that operate to temporarily increase linearity when data transmission is to be performed in a higher order modulation scheme of 64QAM or higher, and the modulation scheme is lowered due to a change in the MCS level. In this case, the number of power amplifiers operating to reduce the increased linearity is reduced.

Controlling the number of power amplifiers operated according to the MCS level in the control unit 300 may be configured to be performed using a lookup table for the control stored therein, or as shown in FIG. 4. The switching element may be configured to directly turn on / off a power amplifier PA by the input MCS level selection signal.

As a result, when the outputs of the power amplifiers 310-1, 2, and n are summed and output in the wireless transmission module 150, the wireless transmitter module 150 operates to support optimal linearity according to the MCS level, thereby transmitting data in a higher-order modulation scheme. Even linearity can be supported. In addition, in consideration of the fact that the conventional wireless transmission module that supports linearity when transmitting data of high order as well as low order modulation method is configured to support high transmission power irrespective of the modulation method, the wireless transmission module 150 according to the present invention. ) Is more efficient due to the smaller total current consumption.

4 is a diagram illustrating a configuration of a wireless transmission module 150 according to an exemplary embodiment of the present invention, and a switching device for directly turning on / off a power amplifier power by an MCS level selection signal (a, b, c). The number of power amplifiers used to amplify the transmission data is shown. The power amplifiers in the wireless transmission module 150 may be configured in a series of two stages, for example, in which a plurality of series configurations are possible. Here, reference numeral 430 denotes a power amplifier of a first stage. In the second stage, three power amplifiers (A, B, C) 440, 450, and 460 are connected in parallel.

The switching element is provided with the number of power amplifiers connected in parallel. Accordingly, the first power switch 400 for turning on / off the power of the A power amplifier 440 according to the MCS level selection signals a, b, and c, and the B power amplifier (a) for the MCS level selection signals a, b, and c are provided. The second switch 410 for turning on / off the power of the 450 and the third switch 420 for turning on / off the power of the C power amplifier 460 according to the MCS level selection signals a, b, and c are provided. It is provided.

Table 2 below shows that the first, second, third switches 400, 410, and 420 operate to control the number of power amplifiers PA that operate according to the MCS level selection signals a, b, and c.

MCS Level Selector Output
(a, b, c) Modulation method PA in action ① (1,0,0) QPSK A ② (1,1,0) 16QAM A, B ③ (1,1,1) 64QAM A, B, C

As described above, the wireless transmission module 150 controls the number of power amplifiers (PAs) operating according to the MCS level, so that more power amplifiers operate to support high linearity when transmitting data in a higher-order modulation scheme. . And if the data is transmitted in a lower-order modulation scheme is the opposite. As a result, the wireless transmission module 150 may support higher or lower linearity according to the modulation scheme as shown in FIG. 5.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

100: transmitter 110: encoder
120: channel interleaver 130: modulator
140: MCS level selector 150: wireless transmission module
160: transmitting antenna 200: receiver
210: receiving antenna 220: wireless receiving module
230: demodulator 240: channel deinterleaver
250: decoder 260: channel state estimator
300:
310-1,2, n, 430,440,450,460: power amplifier (PA)
400: first switch 410: second switch
420: third switch

Claims (3)

The present invention relates to a wireless transmission module that varies linearity in signal transmission according to a modulation and coding scheme (MCS) level of a signal received by a wireless terminal.
A plurality of power amplifiers (PAs) connected in parallel to amplify and output input data; And
And a controller for controlling power on / off of each of the plurality of power amplifiers according to a modulation and coding scheme (MCS) level for transmitting the data.
The wireless transmission module for outputting the sum of the output of at least one power amplifier that is powered on (On) by the control unit.
The method of claim 1,
The control unit,
According to the MCS level, the power of each of the plurality of power amplifiers is turned on so that more power amplifiers are powered on than in the case of transmitting the data in the higher order modulation method than in the case of the low order modulation method. / Off (Off) characterized in that the wireless transmission module.
The method of claim 1,
The control unit,
And at least one switching element for turning on / off power of each of the plurality of power amplifiers according to the MCS level.

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