JPH05336188A - Multi-value qam transmitter - Google Patents

Abstract

PURPOSE:To reduce the deterioration in a 16QAM transmitter in the case of transmission of a pilot symbol concerning the 16QAM transmitter transmitting, e.g. a data symbol and the pilot symbol. CONSTITUTION:A multi-value QAM transmitter 1 by using a signal inserted with a pilot symbol at a designated location in a time slot and with a data symbol at the remaining positions to generate and transmit a multi-value QAM modulation wave is provided with a pilot symbol generating means 3 generating a symbol located at a coordinates expressed in an integral number for both I, Q axis signals but different from coordinates for a data symbol and having a prescribed amplitude less than a maximum amplitude of the multi-value QAM modulation wave and a phase as a pilot symbol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 16QAM transmitter for transmitting, for example, data symbols and pilot symbols.

At the present time, when data is transmitted by the 16QAM modulation method, a pilot symbol of a known value is transmitted from the transmitting side. On the receiving side, the amplitude attenuation and phase difference are calculated from the above known values and the detected pilot symbols, and these are added to the received data symbols to correct the data symbols so that the data symbols can be received correctly. However, it is necessary to reduce the deterioration of the 16QAM transmitter when transmitting pilot symbols.

[0003]

2. Description of the Related Art FIG. 4 is a transmission time slot format diagram, FIG. 5 is a configuration diagram of a main part of a conventional 16QAM transmitter, and FIG. 6 is an operation explanatory diagram of FIG.

The operation of FIG. 5 will be described below with reference to FIGS. First, as shown in FIG. 4, 1 of 16QAM modulation method
Time slot (hereinafter abbreviated as TS) is, for example, 60
Symbols (the numbers in the figure indicate the number of symbols), and the first three symbols S ₁₁ , S ₂₁ ,, S ₃₁ ,, S ₄₁ (hatched portions in the figure) are the synchronization symbol parts, P ₁₁ , P ₂₁ ,, P ₃₁ , P ₄₁ is the pilot symbol part, and the rest is the data symbol part.

Incidentally, a synchronization symbol portion and a pilot symbol portion (hereinafter referred to as pilot symbol) in one TS.
Has 10 symbols inserted. Further, in FIG. 6, the mark x indicates a pilot symbol, and the mark o indicates a data symbol, but the amplitudes of the former are all (3 ² +3 ² ) ^1/2 = 18 ^1/2 , and the phase is set to the following value. ..

The degree is omitted. First, second, and third symbol parts of S ₁₁ : −22.5, −112.
5, −22.5 S _21st , 1st, 2nd and 3rd symbol parts: +112.5, −15
7.5, ＋112.5 1st, 2nd and 3rd symbol part of S ₃₁ : -112.5, ＋15
7.5, -112.5 S _41st , 2nd and 3rd symbol parts: +22.5, +112.
5, ＋ 22.5 P ₁₁ , P ₂₁ , P ₃₁ , P ₄₁ Symbol part _: −22.5, ＋112.5,
−112.5, +22.5 Next, the coordinates on the I-axis and the Q-axis (hereinafter referred to as pilot symbol data) corresponding to the amplitude and phase values taken by each pilot symbol are written in the ROM 21 in advance. .. Therefore, the transmission code processing unit 11 in the 16QAM transmission apparatus controls the selector 111 by using the timing signal generated internally to select the data or the pilot symbol data read from the ROM and select the format shown in FIG. Generate the signal.

The 16QAM modulator 12 utilizes the signals of these formats to generate a 16QAM modulated wave,
A built-in power amplifier (not shown) sends out at a predetermined frequency and transmission power to the outside.

As shown in FIG. 6, the pilot symbol is transmitted 10 times for each TS at the maximum transmission power (for example, about 30 W). This is because reception is performed with few errors as described above. Is.

[0009]

Here, the power amplifier in the 16QAM transmitter transmits pilot symbols at the maximum transmission power 10 times for each TS.
There is a problem that the QAM transmitter deteriorates quickly.

The present invention, when transmitting pilot symbols,
The purpose is to reduce the deterioration of the 16QAM transmitter.

[0011]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, reference numeral 1 is a multilevel QAM transmitting apparatus that generates and transmits a multilevel QAM wave using a signal in which a pilot symbol is inserted at a specified position in a time slot and a data symbol is inserted at another specified position.

Further, although 3 is arranged at coordinate positions represented by integers on both the I-axis and the Q-axis, it is a symbol arranged at a coordinate position different from the coordinate position assigned to the data symbol, and The pilot symbol generating means generates a symbol having a predetermined amplitude and phase lower than the maximum amplitude of the value QAM wave as a pilot symbol.

[0013]

[Operation] In order to reduce the deterioration of the 16QAM transmitter, it is necessary to reduce the amplitude component of the pilot symbol or reduce the number of times the pilot symbol is transmitted within one TS.

In the latter case, as described above, the accuracy of correction on the receiving side deteriorates, and it becomes difficult to correct the amplitude and phase of the received data symbol. In the present invention, the amplitude component of the pilot symbol is reduced from 18 ^1/2 to, for example, 5 ^1/2 , and the coordinate positions of the pilot symbol I axis and Q axis are set to values represented by integers. 16QAM
It is possible to reduce deterioration of the transmission device and facilitate handling.

[0015]

2 is a block diagram of an embodiment of the present invention, and FIG.
FIG. 7 is an operation explanatory diagram of FIG. Here, the ROM 31 is a component of the pilot symbol generating means 3. Further, the same reference numerals denote the same objects throughout the drawings.

The operation of FIG. 2 will be described below with reference to FIGS. 3 and 4. The parts described in detail above will be briefly described, and the part of the present invention will be described in detail. The position of the pilot symbol of the present invention is indicated by an X mark in FIG. 3, but the position of the data symbol is the same as that of the conventional example.

First, the amplitudes of the pilot symbols (including the synchronization symbol portion and the pilot symbol portion as described above) in FIG. 4 are all 5 ^1/2 and the phases are as follows. The degree is omitted. First, second and third symbol parts of S ₁₁ : −26.566, −11
6.435, −26.565 S ₂₁ , 1st, 2nd and 3rd symbol parts: +116.435, −
153.435, the first, second, third symbol part of +116.435 S _31: -116.435, +
153.435, -116.435 S _41st , 2nd and 3rd symbol parts: +26.565, +15
_{3.435, +26.565 P 11, P 21} , the symbol portion of the _{P 31, P 41: -26.565,} +116.
435, −116.435, +26.565 Note that the amplitude is 5 ^1/2 and the phase is ± 26.565, ± 116.435, ± 15.
The coordinates of I-axis and Q-axis with respect to 3.435 are (+2, ± 1), (−1, ±
2), (−2, ± 1).

Now, in the ROM 31, the coordinates of the I-axis and the Q-axis corresponding to the amplitude and phase values taken by each pilot symbol are written in advance. Therefore, the transmission code processing unit 11 in the 16QAM transmission apparatus controls the selector by using the timing signal generated internally to select the data or the coordinates of the I-axis and the Q-axis read from the ROM 31 and select the data shown in FIG. Generate a signal in the format shown.

As a result, the amplitude component of the pilot symbol is reduced from 18 ^1/2 to 5 ^{1/2, which} is about 1/2, so that the deterioration of the power amplifier is reduced. In addition, the coordinates of both the I and Q axes are represented by integers, making them easy to handle.

[0020]

As described in detail above, according to the present invention, it is possible to reduce the deterioration of the 16QAM transmitter when transmitting pilot symbols.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of FIG. 2;

FIG. 4 is a transmission time slot format diagram.

FIG. 5 is a configuration diagram of a main part of a 16QAM transmission device of a conventional example.

FIG. 6 is an operation explanatory diagram of FIG. 5;

[Explanation of symbols]

 1 Multilevel QAM transmitter 2 Pilot symbol generating means

Claims (1)

[Claims] 1. A multilevel Q for generating and transmitting a multilevel QAM modulated wave by using a signal in which a pilot symbol is inserted at a designated position in a time slot and a data symbol is inserted at the remaining position.
In the AM transmitter (1), the I-axis and the Q-axis are arranged at coordinate positions represented by integers, but the symbols are arranged at coordinate positions different from the coordinate positions assigned to the data symbols, and A multi-level QAM transmitter, comprising pilot symbol generating means (3) for generating, as a pilot symbol, a symbol having a predetermined amplitude and phase lower than the maximum amplitude of the multi-level QAM modulated wave.