JP2000332725A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce memory capacity, without deteriorating AGC and synchronization accuracy. SOLUTION: A timing control section 106 controls a selector 105, so that a selector 105 outputs a pilot symbol for an AGC use symbol period, outputs a synchronization symbol for a synchronization symbol period, or outputs a pilot symbol for a phase reference symbol period. Then the selector 105 properly selects transmission data and a known signal after modulation processing, on the basis of an output of the timing control section 106 and outputs the selected signal to form a frame format of the transmission signal, an IFFT processing section 107 applies IFFT processing to the transmission signal, a guard period insertion section 108 inserts a guard period to a pre-stage of a valid symbol if the transmission signal, a transmission processing section 109 applies transmission processing to the transmission signal and an antenna 110 transmits the transmission signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a transmitting device,
In particular, the present invention relates to a transmission device used for OFDM mobile communication and a transmission signal generation method thereof.

[0002]

2. Description of the Related Art A conventional OFDM transmission apparatus adds three types of known signals, an AGC symbol, a synchronization symbol, and a phase reference symbol, to a valid symbol as a preamble.

Hereinafter, a conventional transmitting apparatus will be described with reference to FIGS. 6 and 7. FIG. 6 is a main block diagram showing a schematic configuration of a conventional transmitting apparatus, and FIG. 7 is a conventional OF apparatus.
FIG. 3 is a schematic diagram illustrating a frame format of a DM transmission signal.

In FIG. 6, a modulation section 601 modulates transmission data, and a memory 602 is a memory for holding a known signal, and includes a pilot symbol storage section 603, a synchronization symbol storage section 604, an AGC symbol And a storage unit 605.

[0005] The selector 606 includes a timing controller 60.
Based on the output of 7, the transmission data after the modulation processing and the known signal are appropriately switched and output, a frame format is formed, and a transmission signal is generated.

[0006] IFFT processing section 608 converts the transmission signal into an IF signal.
After performing FT processing, guard section insertion section 609 inserts a guard section before the effective symbol (transmission data) of the transmission signal, and transmission processing section 610 performs transmission processing on the transmission signal,
Transmit from the antenna 611.

FIG. 7 shows a frame format of a transmission signal. The transmission signal includes an AGC symbol 701, a synchronization symbol 702, phase reference symbols (pilot symbols) 703 and 704, a guard section 705, and an effective symbol 706. Note that a configuration in which the phase reference symbol is only one OFDM symbol may be used.

[0008] As described above, the conventional transmitting apparatus provides three types of known signals to be added as a preamble: an AGC symbol, a synchronization symbol, and a phase reference symbol (pilot symbol). AGC, synchronization acquisition, and phase compensation can be performed.

[0009]

However, the conventional transmitting device needs to hold three different types of known signals that are uncorrelated with each other in advance, and has a problem that the memory capacity becomes large.

[0010] Further, a proposal to solve this problem by using the same signal for the AGC symbol and the synchronization symbol (for example, in 1999, IEICE B-5)
-10).

However, according to the proposed method, when the reception level is low, the forward correlation power decreases and the rear timing error increases, and when the reception level is high, the forward correlation power decreases. Since the timing error becomes higher and the timing error in the front increases, a new problem arises that the synchronization error increases in any case.

[0012] The present invention has been made in view of the above, and an object of the present invention is to provide a transmitting apparatus that reduces the memory capacity without lowering the AGC accuracy and the synchronization accuracy.

[0013]

The gist of the present invention is to use a pilot symbol held in advance not only as a phase reference symbol but also as an AGC symbol, so that a known signal used only for an AGC symbol is obtained in advance. This is to eliminate the need for holding the data and reduce the memory capacity.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A transmitting apparatus according to a first aspect of the present invention includes at least an effective symbol including transmission data,
A transmission signal for generating an OFDM transmission signal to which a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation have been added so that the known signal for AGC and the known signal for phase compensation are the same known signal. A configuration including a generating unit and a transmitting unit that performs inverse Fourier transform on the generated transmission signal and transmits the signal is employed.

[0015] A transmitting apparatus according to a second aspect of the present invention, in the first aspect, adopts a configuration in which the same known signal is a pilot symbol.

According to these configurations, the AGC symbol is composed of the same pilot symbol as the phase reference symbol, and it is not necessary to previously hold a known signal used only for the AGC symbol. The memory capacity can be reduced.

According to a third aspect of the present invention, in the transmission apparatus according to the first aspect or the second aspect, the transmission signal generation means may be configured such that the transmission signal generating means has a length of 1 / 2n of 1 OFDM symbol length (where n is a positive integer). ), A configuration having a subcarrier selection unit for controlling so as to add the known signal for AGC to only the subcarriers whose subcarrier number is an integral multiple of 2n is adopted.

According to this configuration, the subcarrier number is 2
AGC symbols are added only to subcarriers that are integral multiples of n, and the AGC symbol length is set to 1 / 2n of 1 OFDM symbol length.
It is possible to reduce GC symbols and improve transmission efficiency.

[0019] In the transmission apparatus according to a fourth aspect of the present invention, in the third aspect, the transmission signal generating means may be configured such that the amplitude of the AGC known signal section is larger than the amplitude of another known signal section. A configuration having an amplitude converter for converting the amplitude in advance is employed.

[0020] In a transmission apparatus according to a fifth aspect of the present invention, in the fourth aspect, the subcarrier selection section outputs a known signal for AGC having a length of 1/4 of the OFDM symbol length to a subcarrier having four subcarriers. The amplitude conversion unit adopts a configuration in which the amplitude of the signal in the known signal section for AGC is bit-shifted to double the amplitude by adding the subcarrier only to an integer multiple of the subcarrier.

According to these configurations, since the amplitude of the AGC symbol is made larger than the other symbols in advance, even when the AGC symbol is added only to a predetermined subcarrier, the accuracy of the AGC at the receiving station side is increased. Degradation can be prevented.

A communication terminal according to a sixth aspect of the present invention employs a configuration including the transmission device according to any one of the first to fifth aspects.

A base station apparatus according to a seventh aspect of the present invention comprises:
A configuration for performing wireless communication with the communication terminal device according to the sixth aspect is employed.

[0024] A base station apparatus according to an eighth aspect of the present invention comprises:
A configuration including the transmission device according to any one of the first to fifth aspects is adopted.

A communication terminal apparatus according to a ninth aspect of the present invention employs a configuration for performing wireless communication with the base station apparatus according to the eighth aspect.

According to these configurations, the pilot symbol held in advance is used not only as a phase reference symbol but also as an AGC symbol, so that A
Since it is unnecessary to previously store the known signal used only for the GC symbol, the memory capacity can be reduced without lowering the AGC accuracy and the synchronization accuracy.

[0027] A transmission signal generation method according to a tenth aspect of the present invention is directed to an OFDM system in which at least a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation are added to an effective symbol including transmission data. Transmit signal to AG
The known signal for C and the known signal for phase compensation are generated so as to be composed of the same known signal.

A transmission signal generation method according to an eleventh aspect of the present invention is directed to an OFDM system in which at least a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation are added to an effective symbol including transmission data. Transmit signal to AG
The known signal for C and the known signal for phase compensation are generated so as to consist of pilot symbols.

According to these methods, the AGC symbol is composed of the same pilot symbol as the phase reference symbol, and it is not necessary to previously hold a known signal used only for the AGC symbol. The memory capacity can be reduced.

A transmission signal generation method according to a twelfth aspect of the present invention is the transmission signal generation method according to the tenth or eleventh aspect, for an AGC having a length equal to 1 / 2n of 1 OFDM symbol length (n is a positive integer). The known signal is added only to the subcarrier whose subcarrier number is an integral multiple of 2n.

According to this method, when the subcarrier number is 2
AGC symbols are added only to subcarriers that are integral multiples of n, and the AGC symbol length is set to 1 / 2n of 1 OFDM symbol length.
It is possible to reduce GC symbols and improve transmission efficiency.

In the transmission signal generating method according to a thirteenth aspect of the present invention, in the twelfth aspect, the amplitude is converted in advance so that the amplitude of the known signal section for AGC becomes larger than the amplitude of the other known signal sections. I did it.

According to this method, since the amplitude of the AGC symbol is made larger than that of the other symbols in advance, even when the AGC symbol is added only to a predetermined subcarrier, the accuracy of the AGC accuracy at the receiving station side is increased. Deterioration can be prevented.

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

(Embodiment 1) The transmitting apparatus according to the present embodiment also uses pilot symbols as AGC symbols.

The symbol for AGC is provided on the receiving station side.
Any signal can be used since only the reception level is detected. In addition, the accuracy of synchronization acquisition at the receiving station does not deteriorate if the AGC symbol and the synchronization symbol are uncorrelated.

Therefore, in the present embodiment, the AGC symbol is composed of the same pilot symbol as the phase reference symbol.

Hereinafter, the transmitting apparatus according to the present embodiment will be described using FIG. 1 and FIG. FIG. 1 is a main block diagram showing a schematic configuration of a transmitting apparatus according to Embodiment 1 of the present invention. FIG. 2 is a frame format of a transmission signal generated by transmitting apparatus according to Embodiment 1 of the present invention. FIG.

In FIG. 1, a modulation section 101 modulates transmission data, and a memory 102 is a memory for holding a known signal, and includes a pilot symbol storage section 103 and a synchronization symbol storage section 104.

The selector 105 is connected to the timing controller 10
Based on the output of No. 6, the transmission data after the modulation processing and the known signal are appropriately switched and output to generate a frame format of the transmission signal.

Here, the timing control unit 106
The selector 105 is controlled to output a pilot symbol in the C symbol section, output a synchronization symbol in the synchronization symbol section, and output a pilot symbol in the phase reference symbol section.

The IFFT processing section 107 converts the transmission signal into an IF
After performing FT processing, guard section insertion section 108 inserts a guard section before the effective symbol (transmission data) of the transmission signal, and transmission processing section 109 performs transmission processing on the transmission signal,
Transmit from antenna 110.

FIG. 2 shows a frame format of a transmission signal. The transmission signal includes an AGC symbol (pilot symbol) 201, a synchronization symbol 202, phase reference symbols (pilot symbols) 203 and 204, a guard interval 205, and an effective symbol 206. Note that a configuration in which the phase reference symbol is only one OFDM symbol may be used.

Next, the operation of the transmitting apparatus having the above configuration will be described.

The transmission data is subjected to modulation processing by modulation section 101 to become an effective symbol. The effective symbol is determined by the selector 105 controlled by the timing control unit 106.
Thus, an AGC symbol (pilot symbol), a synchronization symbol, and a phase reference symbol (pilot symbol) are added in a frame format as shown in FIG.

The transmission signal obtained by adding a known symbol to an effective symbol is subjected to IFFT processing by IFFT processing section 107, a guard section is inserted before the effective symbol by guard section insertion section 108, and transmission processing is performed by transmission processing section 109. , From the antenna 110.

As described above, according to the present embodiment, AG
The C symbol is composed of the same pilot symbol as the phase reference symbol, and it is not necessary to previously store a known signal different from the pilot symbol for the AGC symbol, so that the memory capacity can be reduced. it can.

The receiving station receiving the OFDM signal having the frame format according to the present embodiment
Since the synchronization symbol of the OFDM signal has the same configuration as that of the related art, synchronization can be obtained by the same processing as that of the related art, and there is no need to particularly change the device configuration. Therefore,
It can be used in combination with any conventionally proposed synchronization acquisition method.

(Embodiment 2) The transmitting apparatus according to the present embodiment has the same configuration as that of Embodiment 1 except that AGC
Symbols are added only to subcarriers whose subcarrier number is an integral multiple of 2, and at the same time, the length of AGC symbols to be added is set to 1 / OFDM symbol length.
2 in length.

In the OFDM wireless communication, if the angular frequency of subcarrier 1 is ω, the angular frequency of subcarrier n can be expressed as nω. Therefore, for example, the subcarrier 2 has a half period of the subcarrier 1, and a signal corresponding to one period exists in a half time of one OFDM symbol period.

The AGC symbol is used only for measuring the reception level after the signals of all the subcarriers are combined on the receiving station side, and need not be added to each subcarrier.

Therefore, in the present embodiment, an AGC symbol is added only to subcarriers (subcarriers 2, 4, 6, 8,...) Whose subcarrier number is an integral multiple of 2, and the AGC symbol is further added. The symbol length is １ ／ of the OFDM symbol length.

Hereinafter, the transmitting apparatus according to the present embodiment will be described using FIG. 3 and FIG. FIG. 3 is a main block diagram illustrating a schematic configuration of a transmitting apparatus according to Embodiment 2 of the present invention. FIG. 4 is a diagram illustrating a conventional transmitting apparatus and a frame format of a transmission signal according to Embodiment 2 of the present invention. It is a schematic diagram which shows a part of. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 3, switch 301 selectively outputs a pilot symbol or 0 signal to selector 105 based on the output of timing control section 106. In the AGC symbol section, the timing control section 106 sets the known signal input to the selector 105 as a pilot symbol in a subcarrier whose subcarrier number is an integer multiple of 2, and sets the subcarrier number to a value other than an integer multiple of 2. 0 signal (or null signal) in subcarrier
And

Further, the pilot symbol is selected by the selector 105.
１ ／ of one OFDM symbol length
Only the length of is input.

FIG. 4B shows a part of the frame format of the transmission signal according to the present embodiment. Unlike the conventional frame format shown in FIG.
In the above, the AGC symbol 401 is added only to subcarriers whose subcarrier number is an integral multiple of 2, and the length of the AGC symbol 401 is の the length of one OFDM symbol.

As described above, according to the present embodiment, only sub-carriers whose sub-carrier number is an integral multiple of 2
Since a GC symbol is added and the AGC symbol length is set to 1/2 of the 1 OFDM symbol length, the number of AGC symbols included in a transmission signal can be reduced and transmission efficiency can be improved.

The subcarrier to which the AGC symbol is added is not limited to a subcarrier whose subcarrier number is an integral multiple of 2, for example, one OFDM symbol length only for a subcarrier whose subcarrier number is an integral multiple of 4. May be added with a pilot symbol having a length of 1/4 of
Further, a pilot symbol having a length of 1/8 of one OFDM symbol may be added only to subcarriers whose subcarrier number is an integral multiple of 8.

That is, AGC symbols are added only to subcarriers whose subcarrier number is an integral multiple of 2n (n is a positive integer), and the AGC symbol length is 10 O
By setting the FDM symbol length to 長 n, the AG
Symbols for C can be reduced.

(Embodiment 3) The transmitting apparatus according to the present embodiment has a configuration similar to that of Embodiment 2, except that only the amplitude of the AGC symbol in the preamble is doubled before transmission. Things.

For example, as shown in Embodiment 2, A
When the GC symbol is added to only the subcarriers whose subcarrier number is an integral multiple of 4, compared to the case where the GC symbol is added to all the subcarriers, the AGC on the receiving station side is performed.
AGC because the average power in the symbol section becomes 1/4
Accuracy may deteriorate.

Therefore, in the present embodiment, the AGC
By doubling the amplitude of the pilot symbol added to the transmission signal as a symbol for use in advance, the average power of the AGC symbol section on the receiving station side is made equal to that of other symbol sections.

Hereinafter, the transmitting apparatus according to the present embodiment will be described using FIG. FIG. 5 is a main block diagram showing a schematic configuration of the transmitting apparatus according to Embodiment 3 of the present invention. The same components as those in Embodiments 1 and 2 are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 5, a switch 501 controls a pilot symbol based on the output of the timing control section 106 to provide a 1-bit shifter 502 for an AGC symbol section and a switch 50 for a phase reference symbol section.
3 respectively.

The 1-bit shifter 502 shifts the input pilot symbol by 1 bit to double the amplitude, and outputs it to the switch 503.

The switch 503 operates based on the output of the timing control unit 106 in the AGC symbol section.
If the subcarrier number is an integer multiple of 4, select the output of the 1-bit shifter 502; if the subcarrier number is a subcarrier other than an integer number of 4, select the 0 signal (or null signal). Then, the data is output to the selector 105.

In the phase reference symbol section, the pilot symbol input from switch 501 directly to switch 503 is selected without passing through 1-bit shifter 502 and output to selector 105.

The reason why the amplitude of the AGC symbol section is increased in advance is not limited to the case where the AGC symbol is added only to the subcarrier whose subcarrier number is an integral multiple of four. Also, the amount of increase in amplitude is not limited to twice.

As described above, according to the present embodiment, AG
Since the amplitude of the C symbol is made larger than the other symbols in advance, even when the AGC symbol is added only to a predetermined subcarrier, it is possible to prevent the receiving station from deteriorating the AGC accuracy.

Further, since the amplitude increase is realized by the bit shift, the configuration for increasing the amplitude can be minimized.

It should be noted that the first to third embodiments are described.
Is applicable to a system in which the receiving station performs frequency offset compensation using AGC symbols. Since the detection range of the frequency shift is proportional to the reciprocal of the symbol period, when the period of the AGC symbol is short as in the second or third embodiment, the accuracy of the frequency offset compensation is also improved.

[0072]

As described above, according to the present invention,
By using the pilot symbol held in advance not only as a phase reference symbol but also as an AGC symbol, it becomes unnecessary to previously hold a known signal used only for the AGC symbol.
The memory capacity can be reduced without lowering the accuracy and synchronization accuracy.

[Brief description of the drawings]

FIG. 1 is a main block diagram showing a schematic configuration of a transmitting apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a schematic diagram showing a frame format of a transmission signal generated by a transmission device according to Embodiment 1 of the present invention.

FIG. 3 is a main block diagram showing a schematic configuration of a transmitting apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a schematic diagram illustrating a part of a frame format of a transmission signal according to a conventional transmission device and a second embodiment of the present invention.

FIG. 5 is a main block diagram showing a schematic configuration of a transmitting apparatus according to Embodiment 3 of the present invention.

FIG. 6 is a main block diagram showing a schematic configuration of a conventional transmission device.

FIG. 7 is a schematic diagram showing a frame format of a conventional OFDM transmission signal.

[Explanation of symbols]

 105 selector 106 timing control unit

Claims (13)

[Claims] 1. An OFDM transmission signal in which at least a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation are added to an effective symbol including transmission data,
A transmission signal generating means for generating a known signal for AGC and a known signal for phase compensation so as to be composed of the same known signal, and a transmitting means for performing an inverse Fourier transform on the generated transmission signal and transmitting the signal. Transmitting device. 2. The transmitting apparatus according to claim 1, wherein the same known signal is a pilot symbol. 3. The transmission signal generating means has a length of 1 OF.
AG that is 1 / 2n (n is a positive integer) of the DM symbol length
The transmission device according to claim 1 or 2, further comprising a subcarrier selection unit that controls the known signal for C to be added only to subcarriers whose subcarrier number is an integral multiple of 2n. 4. The transmission signal generating means includes an amplitude converter for converting the amplitude in advance so that the amplitude of a known signal section for AGC becomes larger than the amplitude of another known signal section. 3. The transmitting device according to 3. 5. The apparatus according to claim 1, wherein the subcarrier selection unit has a length of 10
The known signal for AGC, which is 1/4 of the FDM symbol length, is added only to the subcarrier whose subcarrier is an integral multiple of 4, and the amplitude conversion unit shifts the signal of the known signal section for AGC by 1 bit to reduce the amplitude. 5. The transmission device according to claim 4, wherein the transmission is doubled. 6. A communication terminal device comprising the transmission device according to claim 1. Description: 7. A base station apparatus for performing wireless communication with the communication terminal apparatus according to claim 6. 8. A base station apparatus comprising the transmitting apparatus according to claim 1. Description: 9. A communication terminal device for performing wireless communication with the base station device according to claim 8. 10. An OFDM transmission signal in which at least a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation are added to an effective symbol including transmission data, a known signal for AGC and a known signal for phase compensation are added. A method for generating a transmission signal, wherein the signal is generated so as to be composed of the same known signal. 11. An OFDM transmission signal in which at least a known signal for AGC, a known signal for synchronization acquisition, and a known signal for phase compensation are added to an effective symbol including transmission data, a known signal for AGC and a known signal for phase compensation are added. A method for generating a transmission signal, wherein the signal is generated so as to consist of a pilot symbol. 12. The length is one half of the OFDM symbol length.
The transmission signal generation method according to claim 10 or 11, wherein an AGC known signal of n (n is a positive integer) is added only to subcarriers whose subcarrier number is an integral multiple of 2n. 13. The transmission signal generation method according to claim 12, wherein the amplitude is converted in advance so that the amplitude of the known signal section for AGC becomes larger than the amplitude of the other known signal sections.