KR970009676B1 - Apparatus for wireless communication of multi-carrier wave - Google Patents

Abstract

A multiple carrier wave radio-communication apparatus monitors a sub-channel's fading influence, does not transmit a data to a bad sub-channel of a bad channel state, thereby achieving an effective or accurate data transmission. The apparatus includes: a reference symbol supply means for providing a reference symbol allocated in a sub-channel corresponded to a predetermined reference symbol; an amplitude/phase error detector for detecting an amplitude/phase error between a reference symbol of a transmitting part and a reference sykbol of a receiving part; a channel fading influence calculator for calculating a fading influence degree of a corresponding sub-channel; a reference sub-channel selector for selecting a sub-channel according to the fading degree measured by the channel fading influence calculator; a bit distribution regulator for regulating an allocation and a maping of an optimum bit number; a bit distribution and bit mapping means for performing a bit distribution and bit mapping; and a bit back-distribution or bit reading means for receiving each sub-channel's bit, performing a bit back-distribution/reading about the received signal, and transmitting the signal to the amplitude/phase error detector.

Description

Multi-carrier wireless communication device

1 is a schematic diagram of a multi-carrier wireless communication device according to the present invention.

2 is a diagram illustrating an output spectrum of a multicarrier.

* Explanation of symbols for main parts of the drawings

10: Digital data input sequence 20: Bit allocation and bitmapper

30: modulator 40: parallel / serial converter

50: digital / analog converter 60: up-frequency converter

70,80: Antenna 90: Downlink Frequency Converter

100: analog / digital converter 110: serial / parallel converter

120: demodulator 130: bit de-divider and bit reader

140: digital data output sequence 150: bit distribution controller

160: reference symbol supply 170: amplitude, phase detector

180: fading calculator for each channel 190: fading information for each channel

The present invention relates to a multi-carrier wireless communication system, and in particular, checks the fading effect of a multi-carrier modem used in a wireless channel, and if the fading effect exceeds a predetermined limit, the subchannel is fluidly replaced and the multi-channel communication is performed. A device to perform.

In general, since a signal transmitted from a transmitter is received by a receiver through a different propagation path in a radio channel, there is a multipath fading phenomenon in which the received electric field intensity changes with time due to mutual interference or changes in the propagation path state. . This has a big impact on the probability of bit error, and its countermeasures change over time. Therefore, countermeasures must be taken. In particular, when frequency selective fading exists, the subchannels change over time, and thus the fading effect is affected, and thus the transmitted data is damaged.

Accordingly, an object of the present invention is to solve the problems of the prior art described above, and to monitor the effect of fading of each subchannel over time so that data is not transmitted to a subchannel having a very bad channel state. To provide a device for accurate data transmission.

An apparatus of the present invention for achieving the above object is a multi-carrier wireless communication apparatus, comprising: means for supplying a reference symbol for allocating a reference symbol promised in a transmission / reception period to a corresponding subchannel; Means for detecting an amplitude and a phase error for measuring an amplitude and a phase difference between the reference symbol on the transmission side and the detected reference symbol on the receiving side from the reference symbol supply means; Channel fading influence calculation means for measuring the amplitude and phase difference between the reference symbol on the transmitting side and the detected reference symbol on the receiving side from the means for detecting the amplitude and phase error to calculate the degree of fading influence of the corresponding subchannel; Reference subchannel selecting means for selecting a subchannel according to the degree of fading measured from said fading effect calculation means for each channel; Bit distribution adjusting means for adjusting allocation and mapping of an optimal number of bits for each subchannel selected by the reference subchannel selecting means; Bit distribution and bit mapping means for performing bit distribution or mapping for each channel to be used or transmitted according to the result adjusted by the bit distribution adjusting means; And bit de-distribution and bit reading means for allocating bits of each sub-channel adjusted by the bit distribution adjusting means and debit-distributing and reading the received signal and sending the bits to means for detecting the amplitude and phase error. do.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

1 is a schematic diagram of a multi-carrier wireless communication device according to the present invention. In FIG. 1, reference numeral 10 denotes a digital data input signal, 20 denotes a bit divider and a bitmapper that allocates and maps the optimal number of bits according to fading effects for each subchannel, 30 denotes a modulator, and 40 denotes a A parallel / serial converter, 50 is a digital / analog converter, 60 is an up-frequency converter up frequency, 70 and 80 are antennas, 90 is a down-frequency converter down frequency, 100 is an analog / digital converter , 110 is a serial / parallel converter, 120 is a demodulator, 130 is a bit de-divider and bit reader, 140 is a digital data output signal, 150 is a bit divider, 160 is a reference symbol supply, 170 is an amplitude and A phase detector, 180 is a fading calculator for each channel, 190 is fading information for each channel, and 200 is a reference subchannel selector.

As for the digital data input signal sequence 10 input to the bit divider and bitmapper 20, an optimal number of bits (lattice number) is determined for each subchannel by the bit divider 150 so that N parallel signals are modulated ( 30). Of course, the optimal number of bits has little meaning for the first input signal. As will be described later, the fading effect of each subchannel is checked by the received signal, and then the number of bits of the corresponding channel is determined in consideration of the measured fading influence. The modulator 30 is composed of an Inverse Fast Fourier Transform (IFFT) converting the frequency domain into the time domain. The output signals of the modulator 30 are output as 2N time domain parallel signals. The signal passes through the parallel / serial converter 40 to be converted into a serial signal in the time domain. After passing through the digital / analog converter 50, the frequency is increased by the up-frequency converter 60, and then the air is passed through the antenna 70. Is sent to. This signal will be received at the receiver after passing through the wireless channel, subject to attenuation and fading effects for a variety of reasons. In the receiver, the signal received through the antenna 80 is lowered in the downlink frequency converter 90, and then converted into a digital signal by the analog / digital converter 100, passing through the serial / parallel converter 110, and 2N pieces. After converted into a parallel time domain signal, it is input to a demodulator 120. The demodulator 120 is composed of a Fast Fourier Transform (FFT) that transforms the frequency domain from the time domain. The output signal of the demodulator 120 is a parallel signal in the frequency domain, that is, a component of N multicarrier signals. . The N parallel signal strings have information according to the number of bits of each sub-channel adjusted by the bit divider 150 and are converted into data strings through the bit de-splitter and the bit reader 130 so that the digital data signal string 140 is outputted. do. Then, another signal path of the signal passing through the bit divider and the bit reader 130 is sent to the amplitude and phase error detector 210. The phase error detector 210 detects a difference in amplitude and phase of a signal between a reference symbol of each received subchannel and a reference symbol of a subchannel originally applied to the subchannel. As the reference symbol of the received signal is affected by fading in the air, the reference symbol of the received signal will be distorted in amplitude and phase. The amplitude and phase detector 210 calculates the difference between the detected amplitude and the phase of each subchannel in the fading calculator 220 for each channel, and the influence information of the fading of each subchannel is the reference subchannel selector 240. And the bit distribution controller 170 to adjust the use of each subchannel and the number of bits capable of carrying data. In this case, if the influence of fading exceeds a predetermined threshold, the corresponding subchannel is not used. If the influence of fading is relatively weak, the subchannel may reduce the number of bits. Allocate a large number of bits to carry data.

For the sake of clarity, the matters on the prevention of data loss due to the frequency selective fading will be described with reference to the drawings.

2 is a diagram illustrating an output spectrum of a multicarrier.

In the present invention, in order to reduce data loss due to frequency selective fading, a reference symbol, which is previously accelerated, is inserted into a sub-channel previously promised in a transmission / reception period of the total N sub-channels as shown in FIG. The amplitude and phase error between the known reference symbol and the received reference symbol are detected and the fading effect of the subchannel is measured. Tell the transmitter not to send data on the channel. In this case, the number of subchannels to which the reference symbol is sent is n (n < N, n = 1, 2, ...), and the radio channel is determined according to the environment and frequently receives frequency selective fading over several subchannels. N is increased but considering the transmission efficiency, it is determined to be smaller than the total number of subchannels (N). On the other hand, the selection of the reference symbol among the total N sub-channels are determined sequentially or randomly from sub-channel 1 to N, or if the fading characteristics of the radio channel can be statistically known, selectivity is selected using a separate algorithm. Use the best means to find the subchannels affected by fading.

That is, the present invention can be applied to a multi-carrier modem used in a radio channel whose channel characteristics frequently change in time, so that the state of influence on fading of all sub-channels can be monitored periodically and thus the state is not well received by fading. No data is transmitted on the subchannels.

The present invention configured as described above can prevent data corruption due to fading in multicarrier wireless communication. In addition, since the degree of fading of each subchannel can be known, fading information for each channel can be provided even for a part of equalizing a signal received by a receiver, so that the signal can be equalized accurately.

Claims (3)

A multi-carrier radio communication apparatus, comprising: means for supplying a reference symbol for allocating a reference symbol promised in a transmission / reception period to a corresponding subchannel; Means for detecting an amplitude and a phase error for measuring an amplitude and a phase difference between the reference symbol on the transmission side and the detected reference symbol on the receiving side from the reference symbol supply means; Channel fading influence calculation means for measuring the amplitude and phase difference between the reference symbol on the transmitting side and the detected reference symbol on the receiving side from the means for detecting the amplitude and phase error to calculate the degree of fading influence of the corresponding subchannel; Reference subchannel selecting means for selecting a subchannel according to the degree of fading measured from said fading effect calculation means for each channel; Bit distribution adjusting means for adjusting allocation and mapping of an optimal number of bits for each subchannel selected by the reference subchannel selecting means; Bit distribution and bit mapping means for performing bit distribution or mapping for each channel to be used or transmitted according to the result adjusted by the bit distribution adjusting means; And bit de-distribution and bit reading means for allocating bits of each sub-channel adjusted by the bit distribution adjusting means and debit-distributing and reading the received signal and sending the bits to means for detecting the amplitude and phase error. Multi-carrier wireless communication device characterized in that. The method of claim 1, wherein the selection of subchannels for transmitting a reference symbol in the reference subchannel selecting means for selecting a subchannel for transmitting the reference symbol is performed sequentially or randomly from subchannels 1 to N. Carrier radio communication device. The multi-carrier radio communication as claimed in claim 1, wherein the selection of the subchannel sending the reference symbol in the reference subchannel selecting means for selecting the subchannel sending the reference symbol is an algorithm obtained by statistically obtaining the fading characteristics of the radio channel. Device.