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Orthogonal frequency division multiplexing communication apparatus

A technology of a communication device and a communication method, which is applied in the directions of multiplexing communication, orthogonal multiplexing system, multi-frequency code system, etc., can solve the problems of incapable of phase compensation of user data and deterioration of precision.

Inactive Publication Date: 2005-02-02
WI FI ONE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, in a communication environment, when the level of thermal noise is high, in other words, when the carrier-to-noise ratio (C / N ratio) is low, the accuracy of phase error detection using a known signal deteriorates, resulting in inability to perform accurate The problem of phase compensation

Method used

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  • Orthogonal frequency division multiplexing communication apparatus
  • Orthogonal frequency division multiplexing communication apparatus
  • Orthogonal frequency division multiplexing communication apparatus

Examples

Experimental program
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Effect test

no. 1 example

[0026] Figure 4 is a block diagram of the OFDM communication device according to the first embodiment of the present invention.

[0027] First, the transmission data (message) of each subcarrier is subjected to digital modulation processing in the modulation section 101, such as QPSK (Quadrature Phase Shift Keying) or QAM (Quadrature Amplitude Modulation), and then is subjected to IFFT operation in the IFFT section 102 as OFDM signal.

[0028] The known signal of the pilot frequency is output to the multiplier 103 for amplitude adjustment using a predetermined coefficient. The known signal is subjected to IFFT operation in the IFFT section 102 to be an OFDM signal in the same manner as described above.

[0029] These OFDM signals are converted into baseband signals in the D / A converter 104 . The baseband signal is passed through a low-pass filter (not shown) to remove unnecessary components from the signal, and then amplified in an amplifier to be sent as a transmission si...

no. 2 example

[0042] This embodiment illustrates the case where a message signal is transmitted using a multi-value quadrature amplitude modulation system. When a multi-value quadrature amplitude modulation system (16QAM system is used here) is used to send message signals, the signal points at the receiving end are arranged as Figure 5 shown.

[0043] exist Figure 5 In the signal space diagram shown, since the distance from the origin to the signal point represents the amplitude, the amplitude becomes larger as the distance from the origin becomes longer. That is, in Figure 5 In , the signal points (0010), (1010), (1000) and (0000) have large amplitudes.

[0044] The transmitting end performs carrier allocation, so that the signals respectively corresponding to the above-mentioned signal points become the known signals of the pilot frequency. The amplitudes of these four signal points are larger than those of the other signal points, as described above. Thus, the signals correspond...

no. 3 example

[0050] This embodiment explains a case where a coefficient used in amplitude adjustment is set to a value obtainable by using a bit shifter and addition and subtraction without using a multiplier in order to reduce the hardware scale.

[0051] Figure 6 is a block diagram of an OFDM communication device according to a third embodiment of the present invention. exist Figure 6 in, with Figure 4 The same part is given as with Figure 4 The same reference numerals are used to omit descriptions thereof.

[0052] Figure 6 The OFDM communication device shown is provided with a bit shifter 301 instead of the multiplier 103 . Amplitude adjustment (gain control) is performed by this bit shifter 301 .

[0053] The operation of the OFDM communication apparatus having the above-mentioned structure will be described below.

[0054] The data of the pilot, that is, the known signal is output to the bit shifter 301 for amplitude adjustment (gain control) using a predetermined coeffic...

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Abstract

The known signal that is transmission data for the pilot carrier is output to multiplier 103 to be subjected to amplitude adjustment (gain control) using a predetermined coefficient. The coefficient is set as appropriate in the range that makes an amplitude of the known signal larger than the amplitude of a message signal in consideration of, for example, error rate deterioration and increment of peak power in the entire transmission power. In addition, since the number of pilot carriers is small as compared to the number of all carries, the increment of the gain of the pilot carrier does not generally have a large effect on the increment of the peak power.

Description

technical field [0001] The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) communication device, in particular to an OFDM communication device in a mobile communication system. Background technique [0002] The main factor that causes deterioration of ground wave transmission characteristics in the transmission path is multipath interference. OFDM transmission systems resistant to multipath interference have recently attracted attention. OFDM multiplexes multiple (tens to hundreds) digital modulated signals that are orthogonal to each other within a signal interval. [0003] use Figures 1 to 3 A conventional OFDM communication device will be described. figure 1 is a partial block diagram of a schematic structure of an existing OFDM communication device, figure 2 It is a schematic structural diagram of OFDM sending / receiving signals, image 3 is the signal space diagram of a multivalued modul...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04J11/00H04L27/26
CPCH04L27/2602H04L27/2647H04L27/2657H04L27/2626H04L27/262H04L27/2675H04J11/00
Inventor 须藤浩章
Owner WI FI ONE