JPH05110489A - Radio communication equipment - Google Patents

Abstract

PURPOSE:To eliminate the effect of fading without deteriorating the throughput with small scale hardware. CONSTITUTION:A coder 102 applies error correction coding to parallel data and modulators 103-1-20 modulate each symbol of an error correction code word onto a carrier whose frequency is apart by a coherent band width or over in a transmission line, an adder 104 adds them and the result is sent from a transmission antenna 107. On the other hand, a signal received by a reception antenna 109 is demodulated by demodulators 112-1-20 by a frequency band corresponding to each carrier signal of the reception signal and a demodulation data group is decoded by a decoder 113 applying error decoding it as a reception word.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication device for transmitting data in a frequency selective fading environment.

[0002]

2. Description of the Related Art In mobile communication, since there is frequency selective fading originating from multiple propagation paths, when high-speed data transmission is performed, waveform distortion and intersymbol interference occur, and reliable communication is achieved. Difficult to do. Conventionally, an automatic equalizer has been used to remove this waveform distortion and intersymbol interference.

[0003]

However, when the automatic equalizer is used, (1) it is necessary to send a training signal, which causes an increase in overhead, which leads to a decrease in throughput. (2) High speed In the case of transmission, there is a drawback that the hardware scale of the automatic equalizer increases.

[0004]

According to the present invention, a plurality of carrier waves are used and an information signal and a check signal obtained by error-correcting encoding the information signal are transmitted in parallel, so that the carrier wave that has undergone fading on the receiving side is transmitted. This makes it possible to correct the error in the signal and realizes highly reliable high-speed data transmission.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
Is a serial-parallel converter, 102 is an error correction encoder, 103-
1 to 103-20 are modulators, 104 is an adder, 105 is a mixer, 106 is an amplifier, 107 is a transmitting antenna, 10
8 is a local oscillator, 109 is a receiving antenna, 110 is an amplifier, 111 is a mixer, 112-1 to 111-20 are demodulators, 113 is an error correction decoder, and 114 is a parallel-serial converter.

In the above structure, the input serial data is converted by the serial-parallel converter 101 into parallel data composed of a plurality of symbols (16 symbols in the embodiment, 1 symbol = 2 bits). The parallel data is encoded by the error correction encoder 102 and converted into a plurality of bits of parallel data (20 symbols in the embodiment, 16 inner information symbols, and 4 check symbols).
The parallel data output from the error correction encoder 102 is
Subsequently, each symbol has a plurality of modulators 103-1 to 103-.
20 (in the embodiment, the number of modulators is 2)
0).

Here, the signal bandwidth of each modulator is not more than the coherence bandwidth of the propagation path. The carrier frequencies of the modulators are assumed to be separated from each other by a coherence bandwidth of the propagation path or more. In the embodiment, the modulation method is a four-value modulation method (QPSK or the like). The outputs of the modulators are added by the adder 104 and input to the mixer 105. The mixer 105 uses the addition signal and the local oscillator 108.
It is multiplied by the frequency signal input from to output a transmission band signal. The multiplied signal is amplified to a predetermined amplitude by the amplifier 106 and transmitted from the transmitting antenna 107. The state of the transmission signal at this time is shown in FIG.

On the receiving side, the signal input from the receiving antenna 109 is amplified to a predetermined amplitude by the amplifier 110 and input to the mixer 111. The mixer 111 multiplies the signal from the amplifier 110 with the frequency signal from the local oscillator 108, converts the signal into a predetermined frequency signal, and outputs the plurality of demodulators 1
12-1 to 112-20. Multiple demodulators 11
2-1 to 112-20 are a plurality of modulators 103-1 to 10-1.
It has a demodulation band corresponding to each frequency band signal which is an output of 03-20. Demodulators 112-1 to 11
2-20 demodulate the corresponding carrier signals and output them to the error correction decoder 113. The error correction decoder 113 performs error correction decoding on the input data, and then the parallel-serial converter 114 converts the data into serial data and outputs the serial data as received data.

During the above operation, the signal in the section from the transmitting antenna 107 to the receiving antenna 109 is usually subjected to frequency selective fading originating from multiple propagation paths. At this time, since each carrier component of the transmission signal is equal to or less than the coherence bandwidth as described above, it is considered that fading is uniform for each carrier component. Also,
Since the carrier components are separated from each other by more than the coherence bandwidth, it is considered that the fading occurs independently between the carrier components. Therefore, if the error correction code is a random error correction code and the number of carrier components undergoing fading is equal to or less than the correction capability of the code, the error due to fading will be corrected.

That is, this embodiment uses the encoder 102.
, The parallel data is error-correction coded, and the modulator 103-1
20 to 20 respectively modulate each symbol of the error correction codeword into a carrier distant from each other with a frequency equal to or more than the coherent bandwidth of the transmission path and add them by the adder 104 before transmitting antenna 1
Sent from 07. On the other hand, the signal received by the receiving antenna 109 is demodulated by the demodulators 112-1 to 112-20 having the frequency bands corresponding to the individual carrier signals of the received signal, and further, the demodulated data group is subjected to error decoding as a received word. Bowl 1
It is decoded by 13.

FIG. 3 shows a second embodiment. Since the second embodiment is almost the same as the first embodiment, only different points will be described. 215-1 to 215-20 are level detection circuits for detecting the signal strength in the demodulation band of each demodulator,
6 determines a carrier component that has undergone fading from the signal strength of each demodulator, and outputs the information to the error correction decoder 113.
It is an erasure determination circuit that outputs to.

With this configuration, the level detection circuits 215-1 to 215-1
215-20 detects the signal strength of each carrier component and outputs it to the erasure determination circuit 216. The erasure determination circuit 216 determines a carrier component having a signal strength extremely lower than the other carrier components as a carrier component undergoing fading, and uses this information as an error correction decoder 113.
Output to. The error correction decoder 113 performs erasure correction decoding by erasing the information input from the erasure determination circuit 216, that is, demodulated data corresponding to the position of the carrier component undergoing fading. Since there is erasure information, even if the same error correction code as in the first embodiment is used, a higher error correction capability than that in the first embodiment can be realized.

[0013]

As described above, using a plurality of carriers separated by a coherence bandwidth or more, in the frequency axis direction,
In other words, by transmitting codewords subjected to random error correction coding in parallel using each carrier signal as a symbol, it becomes possible to perform error correction or erasure correction on a carrier signal that has undergone fading on the receiving side, and it is highly reliable. It realizes high-speed data transmission in a mobile communication environment.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless communication device embodying the present invention.

FIG. 2 is a spectrum diagram of a transmission signal transmitted from a wireless communication device implementing the present invention.

FIG. 3 is a block diagram showing the configuration of another wireless communication device embodying the present invention.

[Explanation of symbols]

 101 serial-parallel converter 102 error correction encoder 103-1 to 103-20 modulator 104 adder 105 mixer 112-1 to 112-20 demodulator 113 error correction decoder 114 parallel-serial converter 215-1 to 215- 20 Level detection circuit 216 Erasure determination circuit

Claims (3)

[Claims] 1. An error correction coding means for error correcting coding parallel data, and a coherence bandwidth of mutual propagation paths each of which receives each symbol of a codeword output from the error correction coding means as an input. A wireless communication apparatus comprising: a plurality of modulating means having carrier waves having different frequencies; an adding means for adding outputs of the plurality of modulating means; and a sending means for sending an output of the adding means to a propagation path. .. 2. A receiving means for receiving a predetermined frequency band signal from a channel, a plurality of demodulating means having a frequency band corresponding to each received carrier signal, and a demodulated data group which is an output of the demodulating means. And a error correction decoding means for performing error correction decoding as a received word. 3. Level detection means for detecting the signal strength within the demodulation band of the plurality of demodulation means, and an output group of the plurality of level detection means as an input, and a predetermined value or less than the output group of the plurality of level detection means. Detecting the position of the demodulator output having the strength of ## EQU1 ## and determining the demodulation means output as an erasure symbol, the error correction decoding means uses the erasure symbol position which is the output of the erasure determination means. The wireless communication device according to claim 2, which is erasure correction decoding means for performing error correction.