JP2001053714A - Multi-carrier signal transmission device and multi- carrier signal reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a preamble signal with a processing by less delay time by extracting information required for synchronously acquiring a transmission signal, accumulating synchronous data to be received, correlating the output of a filter part with accumulated synchronous data and detecting synchronism by the peak position of a correlation value. SOLUTION: The phase and the power level of the basic wave of a sub- carrier are equal to those of the output of a delay circuit 12. A power level synthesized by an adder 13 becomes twice as much as the other level. Correlation with a value which is set in a preamble buffer 15 is obtained. Thus, the power level becomes a waveform having a peak in the output of an accumulation adder 17. A judgment part 18 judges whether the power level that the accumulation adder 17 accumulates, adds and outputs is not less than a threshold level which is previously set. Thus, the transmission timing of a preamble signal is precisely detected. Consequently, synchronous timing is precisely detected based on the peak detection of the power level by detecting the preamble signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-carrier signal transmitting apparatus and a multi-carrier signal receiving apparatus which are suitably applied to wireless transmission of a multi-carrier signal.

[0002]

2. Description of the Related Art At present, TDMA (Time Division Maltip)
PDC (Personal Digit) based on lex Access) technology
al Cellular) ・ PHS (Personal Handyphone Syste)
m) and communication terminal devices that communicate audio and video using various wireless technologies such as CdmaOne and wireless LAN based on CDMA (Coed Division Maltiplex Access) technology are on the market. On the other hand, with the improvement of the frequency utilization efficiency of broadcasting and mobile communication in recent years, orthogonal frequency division multiplexing (Orthogoanl Frequen
Technology development of a multicarrier scheme called cy Division Multiplexing (OFDM scheme) has been active.

[0003] The OFDM system is a system in which a plurality of carriers (hereinafter, subcarriers) orthogonal to each other are arranged at predetermined frequency intervals within one transmission band, and data is distributed to each subcarrier, modulated, and transmitted. . In this method, the transmitting apparatus virtually arranges transmission data obtained in time series on the frequency axis, allocates transmission data to each subcarrier, and performs multicarrier transmission at predetermined frequency intervals by inverse fast Fourier transform or the like. The signal is orthogonally transformed and transmitted. On the other hand, the receiving apparatus obtains received data as data obtained in a time series by performing a conversion opposite to that performed when transmitting the received multicarrier signal. A transmission signal based on the OFDM method has an advantage that good transmission characteristics can be ensured even in the case of multipath, an advantage that the frequency use efficiency is high, and interference is hardly given to other frequency bands.

FIG. 6 is a diagram showing an example of the configuration of an OFDM radio transmission apparatus. The configuration will be described below. The wireless transmission device 100 here includes a video circuit 101 and an audio circuit 102, and performs encoding processing of the video signal and the audio signal input by the respective circuits 101 and 102.
For example, the video circuit 101 converts a video signal as a moving image into image data of a Moving Picture Expers Group (MPEG) system, and converts a video signal as a still image into a JPEG (Joint Photograhic coding Expers Group).
The image data is encoded by an irreversible image compression encoding method such as a process of converting image data into a system. Or JBIG (Jo
It may be encoded by a reversible image compression method such as an int Bi-level Image Experts Group method. In the audio circuit 102, the MPEG audio system, CELP (Code Excited
Linear Predicttion (PCM), Pulse Code Mod
coding) is performed by a voice coding method such as a coding method.
In addition, an ECC (Error Correcting Code) such as a Reed-Solomon code or a turbo code may be added to the encoded data.

The video data output from the video circuit 101 and the audio data output from the audio circuit 102 are
Then, the data is supplied to an interleaver 104 to be subjected to an interleave process of changing a data arrangement and dispersing a bit sequence. Interleaver 1
The data interleaved in 04 is subjected to modulation processing for transmission by the modulator 105. In this modulator 105,
First, a preamble signal is inserted into a bit sequence, and then, as primary modulation, for example, QPSK modulation (Quadrature Phase)
Shift keying). Note that a modulation method other than QPSK modulation, for example, a modulation method such as BPSK, 8PSK, or QAM may be applied.

[0006] The data primary-modulated by the modulator 105 is supplied to an inverse fast Fourier transform circuit (IFFT circuit) 106, which is arranged on the time axis by a fast Fourier transform operation as a secondary modulation. An inverse Fourier transform process is performed to convert the data into a data array on the frequency axis, and a windowing process for multiplying the window data is performed. This IFFT circuit 106
, The transmission symbol stream virtually arranged on the frequency axis so far is averaged on the time axis to form a transmission sequence.

The output of IFFT circuit 106 is a digital /
The analog signal is supplied to an analog converter 107, converted into an analog signal, and the converted analog signal is converted into a high frequency unit (RF unit).
The signal is supplied to the transmission unit 108 and subjected to high-frequency processing such as filtering and frequency conversion to obtain a transmission signal of a predetermined transmission channel. The processing timing in each circuit in the wireless transmission device 100 is controlled by a time base controller (TBC) 109.

FIG. 7 is a diagram showing a radio receiving apparatus for receiving a signal transmitted from radio transmitting apparatus 100 shown in FIG. The configuration will be described below. The radio receiving apparatus 200 here supplies a signal received by the antenna 201 to a high frequency unit (RF unit) 202 to perform reception processing such as filtering and frequency conversion, and to perform predetermined processing. Obtain the received signal of the channel. The received signal is supplied to an analog / digital converter 203 to be converted into digital data, and the digitally converted received sequence is supplied to a window detection unit 204. The window detection unit 204 performs a synchronization detection process for detecting a break in data to be Fourier-transformed based on window data multiplied in the transmission system from the reception sequence.

Then, the output of the window detecting section 204 is supplied to a fast Fourier transform circuit (FFT circuit) 205, and a Fourier transform operation is performed at the timing of the break of the data detected by the window detecting section 204, and the Fourier transform is calculated. In processing
A conversion process of converting data on the frequency axis into a data array on the time axis is performed. The Fourier-transformed received sequence is output to the demodulator 2
06, and performs a demodulation process for restoring the conversion process performed during transmission, such as QPSK demodulation, to generate a received symbol stream.

[0010] The received symbol stream is supplied to a deinterleaver 207, which performs a deinterleave process of returning the bit sequence dispersed by the interleave process at the time of transmission to an original data array, thereby obtaining a reception encoded bit sequence.
The received encoded bit sequence is supplied to a Viterbi decoder 208, converted into a received information bit sequence by a Viterbi decoding process, the video information in the converted received information bit sequence is supplied to a video circuit 209, and the audio information is converted into audio data. Circuit 210
To supply.

The video circuit 209 decodes the data encoded by the video circuit 101 of the transmission system to obtain the transmitted video data. The audio circuit 210 decodes the data encoded by the audio circuit 102 of the transmission system to obtain transmitted audio data. The processing timing in each circuit in the wireless receiving device 200 is controlled by a time base controller (TBC) 211.

With the above-described configuration, transmission and reception of an OFDM signal are performed. Here, the primary modulation in the modulator 105 at the time of transmission is a modulation method in which the phase of a carrier is discretely changed according to transmission data, and has a great advantage in frequency use efficiency. The IFFT circuit 106
In the inverse Fourier transform processing in, since the bit sequence arranged on the subcarrier is averaged on the time axis, there is a great advantage that it is resistant to interference waves such as fading and shadowing.

[0013]

However, on the side receiving such a signal, there is a problem that each bit sequence cannot be demodulated unless Fourier transform processing is performed in the FFT circuit 205. Also, when receiving, the FFT circuit 2
When the Fourier transform process is performed in step 05, there is a problem that an accurate bit sequence cannot be demodulated unless a break for one modulation (hereinafter referred to as a break) is correctly recognized. In order to solve these problems, the present applicant has previously proposed a method of generating a transmission symbol stream having the configuration shown in FIG. 8 and performing transmission and reception of the OFDM scheme using the symbol stream ( Japanese Patent Application No. 9-191351
issue).

Referring to the transmission symbol stream shown in FIG.
To explain, here, for example, 24 subcarriers
Applied to multi-carrier communication system with one channel
It is an example. 24 subcarriers SC₁~ SC_{twenty four}Both ends of
Subcarrier SC₁And SC_{twenty four}Is a guard carrier
Yes, nothing is transmitted. Provide this guard carrier
That is, there is an interval for each piece of information transmitted in one modulation time.
Then, it becomes resistant to multipath interference. The remaining 22 subs
Career SC_Two~ SC_{twenty three}Is used for transmitting the first information
Subcarrier and subkey used for transmission of the second information
Carriers are divided into Here, one subcarrier
For each of the first information and the second information.
You. That is, the subcarrier SC_Two, SC_Four, SC₆, SC₈, S
C_Ten, SC₁₂, SC ₁₄, SC₁₆, SC₁₈, SC₂₀, SC_{twenty two}The first information
Information is transmitted (modulated) as subcarriers,
Career SC_Three, SC_Five, SC₇, SC₉, SC₁₁, SC₁₃, SC_Fifteen,
SC₁₇, SC ₁₉, SC_{twenty one}, SC_{twenty three}Is transmitted (modulated) by the second information.
As a subcarrier.

[0015] As the first information, a known preamble signal is transmitted. For example, all the preamble signals are set to the same polar coordinate point [0, 0] (the phase at this time is 0). As the second information, data to be actually transmitted (for example, data obtained by encoding a video signal or an audio signal) is transmitted. FIG.
Is the frequency on the horizontal axis, and is shown as a multicarrier signal in which each subcarrier has been subjected to inverse Fourier transform and arranged at regular frequency intervals.

FIG. 9 shows a configuration in which a preamble signal is detected by a preamble signal detection circuit in the receiving device when a signal having the configuration shown in FIG. 8 is transmitted from the transmitting device.
When the received sequence is obtained at the input terminal 91, a signal obtained by delaying the received sequence by the delay circuit 92 and a signal that is not delayed (that is, the signal itself obtained at the input terminal 91) are supplied to the adder 93. And add. The delay circuit 92
This is a circuit that delays by one half of one modulation time of the reception sequence. Here, one modulation time is 240 μs, and the delay circuit 92 performs a delay processing of 120 μs.

By adding the signal delayed by 1/2 modulation time and the signal not delayed by the adder 93, only the preamble signal is extracted from the signals transmitted in the state shown in FIG. Functions as a shape filter. When QPSK modulation is performed as the primary modulation in the modulator 105 on the transmission side, the spectrum of the data has a constant coordinate on the circumference formed by the orthogonal I component and Q component shown in FIG. Points. The preamble signal extracted by the adder 93 is supplied to a shift register 94.

The shift register 94 is a register in which 11-symbol data is set. The shift register 94 compares the correlation with the 11-symbol preamble data previously stored in the preamble buffer 95 by an individual multiplier 96a, Take 96b @ 96g. Each multiplier 96
The outputs of the correlation values of a to 96 g are supplied to the accumulator 97,
The power levels of 11 symbols are cumulatively added, and the output of the added value is supplied to the determination unit 98. The determination unit 98 performs a process of determining whether or not the cumulatively added power level is within a preset range. When determining that the power level is within the preset range, the determination output is output to a terminal 99. To the time base controller 211 in the receiver, and controls the reception timing such as the Fourier transform timing in the FFT circuit 205 based on the timing.

The preamble signal having the configuration shown in FIG. 8 is included in the transmission signal, and based on the detection of the preamble signal on the receiving side, for example, FFT of an OFDM signal is performed.
By adjusting the processing timing in the circuit, there is an effect that synchronization can be easily obtained in the receiving system. However, when the transmission signal shown in FIG. 8 is generated and transmitted, the receiving side must always delay the reception sequence by 変 調 modulation time, and there has been a problem that the configuration of the reception system is complicated accordingly. That is, although the operation is ideal for detecting a preamble signal, the hardware circuit scale is large, and the actual processing time always requires 1/2 modulation time or more, and the circuit scale and processing time can be further reduced. Has been requested.

Further, as the number of preamble signals to be transmitted is smaller, the amount of transmission of other information (second information shown in FIG. 8) can be increased, which is effective for a communication system having a large number of subcarriers. There is a demand that similar processing can be performed with a small number of preamble signals.

An object of the present invention is to make it possible to detect a preamble signal by processing with a small delay time on the receiving side when preamble signals are arranged at regular intervals in a signal transmitted as a multicarrier signal, An object of the present invention is to increase the transmission amount of information other than signals.

[0022]

According to a first aspect of the present invention, there is provided a multicarrier signal receiving apparatus comprising:
In a multi-carrier signal receiving apparatus for receiving a signal transmitted as a multi-carrier signal, a signal arranged at a constant interval between pieces of second information which is other information, When symbols are used, delay means for delaying the received symbol stream by the time of one modulation time / (n + 1), the received symbol stream delayed by the delay means, and the received symbol stream which is not delayed are used. A filter unit for extracting the first information, a synchronous data storage unit for storing synchronization data to be received, and a correlator for correlating an output of the filter unit with the synchronization data stored by the synchronization information storage unit. And determination means for performing synchronization detection based on the peak position of the correlation value of the correlator.

According to the multicarrier signal receiving apparatus of the first invention, the detection of the first information, which is information necessary for acquiring synchronization, is performed by determining the peak position of the correlation value with the previously prepared data detected by the correlator. And synchronous detection can be performed based on the peak position.

According to a second aspect of the present invention, there is provided a multicarrier signal transmitting apparatus, wherein the first information necessary for acquiring synchronization of a transmission signal is a signal in which the first information is arranged at regular intervals between second information as other information. In a multi-carrier signal transmitting apparatus for transmitting the first information as a multi-carrier signal, interleaving means for rearranging the coded bit sequence, bit sequence storing means for storing the bit sequence rearranged by the interleaving means, Transmitting symbol stream generating means for arranging the first information at intervals of the second information, and selecting means for setting the predetermined interval at which the first information is arranged by the transmitting symbol stream generating means, Modulating means for modulating a transmission symbol stream output by the transmission symbol stream generating means. .

According to the multi-carrier signal transmitting apparatus of the second invention, the first information which is information necessary for obtaining synchronization is:
It is possible to generate a transmission symbol stream arranged between the pieces of second information at predetermined regular intervals, modulate the transmission symbol stream, and transmit the modulated symbol stream as a multicarrier signal.

According to a third aspect of the present invention, there is provided a multicarrier signal receiving apparatus in which the first information necessary for acquiring synchronization of a transmission signal is a signal arranged at regular intervals between second information as other information. A multi-carrier signal receiving apparatus for receiving a signal transmitted as a multi-carrier signal, a receiving mode setting means for setting a receiving mode, a delay means for variably setting a delay amount by the receiving mode setting means, Means for extracting the first information by using the received symbol stream delayed by the means and the received symbol stream not delayed, storing a plurality of types of synchronization data to be received, and setting the reception mode setting means A synchronous data storage unit that outputs synchronous data corresponding to the mode set by the control unit, and an output of the filter unit and the synchronization information storage unit. A correlator for obtaining a correlation with the synchronous data to be output by multiplication, a discriminating means for performing synchronization detection based on a peak position of a correlation value of the correlator, and when the discrimination means cannot detect synchronization, the reception mode setting means Control means for changing the set reception mode.

According to the multicarrier signal receiving apparatus of the third invention, when the reception is performed in one of the reception modes and the synchronization cannot be detected from the correlation between the received symbol stream and the stored synchronization data by the correlator, the reception mode Change
By changing the amount of delay in the delay means and the synchronization data for performing the correlation detection, the synchronization can be detected regardless of the mode of the transmitted multicarrier signal.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the present invention is applied to wireless transmission of a multi-carrier signal, and the basic configuration of a transmitting apparatus is the same as that of the conventional wireless transmitting apparatus 100 shown in FIG. Yes, the configuration for transmitting the preamble signal is changed. Also, the basic configuration of a receiving apparatus that receives a multicarrier signal wirelessly transmitted from the transmitting apparatus is the same as that of wireless receiving apparatus 200 shown in FIG. 7 as a conventional example, and a preamble signal included in the received signal is included. The configuration for detecting is changed.
Here, the primary modulation in the modulator included in the transmission device is to perform QPSK modulation here.

In the present embodiment, in order to detect synchronization on the receiving side, a preamble signal is arranged in a multicarrier signal. The arrangement state of the preamble signal is set, for example, to the state shown in FIG. That is, the transmission symbol stream shown in FIG. 2 (however, shown in FIG. 2 as a multi-carrier signal having a frequency on the horizontal axis) will be described.
This is an example applied to a multi-carrier communication system using channels. There a configuration in which a subcarrier SC ₁ to SC ₂₄ 24 are arranged at regular frequency intervals, subcarriers SC ₁ and both ends of the sub-carrier SC ₁ to SC ₂₄ of 24
SC ₂₄ is as a guard carrier and nothing is transmitted. The remaining 22 subcarriers SC ₂ to SC ₂₃ includes a sub-carrier used for transmission of the first information is divided into a sub-carrier used for transmission of the second information. The first information is a known preamble signal. The second information is data that the user actually wants to transmit (for example, data obtained by encoding a video signal or an audio signal).

The arrangement of the first information and the second information is as follows.
Here, two pieces of second information and one piece of first information are exchanged.
They are arranged so that they are mutually placed. That is, the subcarrier S
C_Two, SC _Three, SC_Five, SC₆, SC₈, SC₉, SC₁₁, SC₁₂, SC
₁₄, SC_Fifteen, SC₁₇, SC₁₈, SC₂₀, SC _{twenty one}, SC_{twenty three}The second information
Are used as subcarriers to be transmitted (modulated).
Carrier SC_Four, SC₇, SC_Ten, SC₁₃, SC₁₆, SC₁₉, SC_{twenty two}Of 7
The book is a subcarrier on which the first information is transmitted.
For the first information, here, all seven sub
The information contained in the rear is the polar coordinate point of [0,0]
QPSK modulation is performed as described above. In the following explanation
And modulate it to be this [0,0] polar coordinate point.
Is referred to as absolute modulation.

A signal having the configuration shown in FIG. 2 is generated in the transmitting apparatus, and is transmitted by radio as a multicarrier signal. Then, the wirelessly transmitted multicarrier signal is received by the receiving device. FIG. 1 shows a configuration in which a detection circuit in the receiving apparatus detects a preamble signal in this case. The circuit shown in FIG. 1 is incorporated in a circuit before performing Fourier transform, such as the window detection unit 204 in the receiving apparatus shown in FIG. 7, for example. When the received sequence is obtained at the input terminal 11, a signal obtained by delaying the received sequence by the delay circuit 12 and an undelayed signal (that is, the signal itself obtained at the input terminal 11) are supplied to the adder 13. And add. The delay circuit 12 is a circuit that delays by one-third of one modulation time of the reception sequence. Here, one modulation time is set to 240 μsec, and the delay circuit 12 performs a delay process of 80 μsec.

By adding the signal delayed by 1/3 modulation time and the signal not delayed by the adder 13, only the preamble signal is extracted from the signals transmitted in the state shown in FIG. Functions as a shape filter. That is, the second
The first information is arranged at regular intervals between the information of
Assuming that the fixed interval is n, one modulation time / (n + 1)
The delay time of the delay circuit 12 is determined by the following equation. Here, Figure 2
As shown in (1), one piece of first information is arranged at a constant interval between two pieces of second information, so that n becomes 2 and 1 modulation time / (2 + 1) = 240 μsec / 3 = 80 μsec. Become.

The preamble signal extracted by the adder 13 is supplied to a shift register 14. Shift register 1
Reference numeral 4 denotes a register in which data of 7 symbols is set. The preamble buffer 15 stores preamble data of 7 symbols in advance. Correlation between data set in the shift register 14 and data previously stored in the preamble buffer 15 is performed by individual multipliers 16a, 16b１６16n for each symbol value.

The output of the correlation value of each of the multipliers 16a to 16n is supplied to a cumulative adder 17, which cumulatively adds the power levels of seven symbols, and supplies the output of the added value to a decision unit 18. The determining unit 18 performs a process of determining whether or not the cumulatively added power level is equal to or higher than a preset threshold level. When determining that the power level is equal to or higher than the threshold level, the determination unit 18 outputs the determination output from the terminal 19 to the terminal device. It is supplied to a reception timing control means (a circuit corresponding to the time base controller 211 in FIG. 7) to control the processing timing in the FFT circuit or the like based on the determined timing.

Here, the principle of detecting a preamble signal by detecting a correlation with the circuit shown in FIG. 1 will be described. The modulation process performed on the signal received at this time, that is, the modulation in the modulator 105 in the transmission device 100 is
Because of QPSK modulation, as shown in FIG. 3, four points ([0,0] / [1,0] / [0,0] on a circle on a rectangular coordinate axis formed by orthogonalizing the I component and the Q component. 1] /
QPSK modulation in which the phase position of any one of [1, 1]) is transmitted as data. FIG.
For the second information shown in (1), any one of these four points is selected. On the other hand, the first information is absolutely modulated so as to be at the phase position of the polar coordinate point [0, 0].

It is assumed that the signal thus modulated and transmitted by radio is received by the receiving apparatus without interference in an ideal radio environment. The fundamental wave of the subcarrier received at this time is expressed as cos (2πft), cos (4πft), ‥‥ cos (2n
πft) and ‥‥ cos (48πft), a total of 22 lines (excluding two for guard band), the waveform delayed by 80 μs is cos ｛2πf (t + 1 / (3f))｝, cos ｛4πf (t + 1 / (3
f))｝, ‥‥ cos ｛2nπf (t + 1 / (3f))｝, ‥‥ cos ｛48
πf (t + 1 / (3f))}, where N = 0th to 23rd subcarriers and k = 0 to 7 are integers, the adder 1 shown in FIG.
The output of No. 3 is one of the following three types. When N = 3k, cos (2Nπft) + cos ｛2Nπf (t + 1 / (3f))｝ = sin (2nπft-2π / 3) When N = 3k + 1, cos (2Nπft) + cos ｛2Nπf ( t + 1 / (3f))｝ = sin (2nπft + 2π / 3) When N = 3k + 2, cos (2Nπft) + cos ｛2Nπf (t + 1 / (3f))｝ = 2sin (2nπft)

FIG. 3 illustrates the above equation in a diagram. FIG. 3A shows the case where N = 3k, and # 11
Is the phase and power level of the fundamental wave of the subcarrier (the size of the arrow: the same applies hereinafter), # 12 is the phase and power level of the output of the delay circuit 12, and # 13 is the output of the adder 13 forming the comb filter. Phase and power level. FIG. 3B shows the case where N = 3k + 1, where # 21 is the phase and power level of the fundamental wave of the subcarrier, # 22 is the phase and power level of the output of the delay circuit 12, and # 23 is the phase and power level of the output of the adder 13 constituting the comb filter. FIG. 3C shows a case where N = 3k + 2.
# 31 is the phase and power level of the subcarrier fundamental wave,
# 32 is the phase and power level of the output of the delay circuit 12,
Reference numeral 33 denotes the phase and power level of the output of the adder 13 constituting the comb filter.

When N = 3k + 2, the phase and power level # 31 of the fundamental wave of the subcarrier are equal to the phase and power level # 32 of the output of the delay circuit 12, and the power level synthesized by the adder 13 # 33 is twice as high as the other levels.

Accordingly, by calculating the correlation value with the value set in the preamble buffer 15, the power level when N = 3k + 2 becomes the power level when N = 3k or N = 3k + 1. , And appears as a waveform having a peak in the output of the accumulator 17. Then, the determination unit 18 determines whether or not the power level output by the cumulative addition by the cumulative adder 17 is equal to or higher than a preset threshold level, so that the transmission timing of the preamble signal can be accurately detected. . For example, the data at the detected timing is supplied to a time base controller in the receiving device, and the Fourier transform is executed by the FFT circuit at that timing, so that Fourier transform processing can be performed at accurate timing.

As described above, the multi-carrier signal having the configuration shown in FIG. 2 is received, and the preamble signal is detected by the circuit having the configuration shown in FIG. 1, whereby the synchronization timing can be accurately determined based on the peak detection of the power level. Can be detected. In this case, the amount of delay in the delay circuit 12 can be reduced as compared with the conventional circuit shown in FIG. 9, and the storage capacity of the memory constituting the delay circuit can be reduced accordingly.
The number of stages such as 4 and the buffer 15 can be reduced, and the circuit scale can be reduced accordingly.

The specific structure of the one-channel signal described in the present embodiment is not limited to the above. That is, the number of subcarriers, the used bandwidth, the subcarrier interval, and the number of preamble signals can take various values according to the data to be transmitted and the purpose of use. For example, in the example shown in FIG. 2, 1 is set for every two pieces of second information.
Three pieces of first information (preamble signal) are arranged,
A preamble signal may be arranged at regular intervals between two pieces of second information. When preamble signals are arranged every third of these, the delay circuit 12 shown in FIG.
Is 60 μs (when one modulation time is 240 μs), and the circuit scale can be further reduced.
Further, in the configuration shown in FIG.
Although the processing is performed by hardware, such a processing may be performed by software.

Although the adder 13 shown in FIG. 1 is used as a circuit constituting the comb filter, another circuit such as a subtractor may be configured to function as a similar filter.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

The present embodiment is also applied to the case of performing wireless transmission of a multicarrier signal using 24 subcarriers as one channel, and the basic configuration of the transmitting apparatus is shown in FIG. Wireless transmission device 1 shown in FIG.
This is the same as 00, except that the configuration for transmitting the preamble signal is changed. Also, the basic configuration of a receiving apparatus that receives a multicarrier signal wirelessly transmitted from the transmitting apparatus is the same as that of wireless receiving apparatus 200 shown in FIG. 7 as a conventional example, and a preamble signal included in the received signal is included. The configuration for detecting is changed. Note that the primary modulation in the modulator provided in the transmitting apparatus is QPS
It is assumed that K modulation is performed.

In this embodiment, the transmitting device
In generating a transmission symbol stream,
As a process for arranging the reamble signal, the first mode and the
Two kinds of arrangement states of the second mode are prepared. here
Are described in FIG. 2 described in the first embodiment or in the conventional example.
As shown in FIG. 8, 24 subcarriers SC₁~ SC
_{twenty four}Subcarrier SC at both ends of₁And SC_{twenty four}Is a guard
Rear and the remaining 22 subcarriers SC_Two~ SC_{twenty three}To
A subcarrier used for transmitting the first information;
It is divided into subcarriers used for transmitting information.

In the first mode, the first embodiment
As shown in FIG. 2 already described in the state, two pieces of second information
And one piece of first information is arranged alternately.
You. That is, the subcarrier SC_Two, SC_Three, SC_Five, SC₆, S
C₈, SC₉, SC₁₁, SC₁₂, SC₁₄, SC _Fifteen, SC₁₇, SC₁₈, SC
₂₀, SC_{twenty one}, SC_{twenty three}Is the sub-information on which the second information is transmitted (modulated).
As a carrier, subcarrier SC_Four, SC₇, SC_Ten,
SC₁₃, SC₁₆, SC₁₉, SC_{twenty two}The first information is transmitted through the seven
Subcarriers.

In the second mode, as shown in FIG. 8, which has already been described as a conventional example, the sub-carriers are alternately divided into first information and second information. That is, the sub-carrier _{SC 2, SC 4, SC 6} , SC 8, SC 10, SC 12, S
C ₁₄ , SC ₁₆ , SC ₁₈ , SC ₂₀ , SC ₂₂ are used as subcarriers for transmitting (modulating) the first information.
_{C 3, SC 5, SC 7} , SC 9, SC 11, SC 13, SC 15, SC 17, SC
_19, the SC _21, SC ₂₃ the second information is a sub-carrier to be transmitted (modulation).

In both the first mode and the second mode, the first information is absolutely modulated so that the information contained in all subcarriers has the phase of the polar coordinate point [0, 0]. I have. As for the second information, data to be actually transmitted (for example, data obtained by encoding a video signal or an audio signal) is transmitted.

FIG. 4 is a diagram showing a circuit configuration for generating both the transmission symbol stream of the first mode arrangement and the transmission symbol stream of the second mode arrangement. The circuit shown in FIG. 4 is a circuit replacing the modulator 105 in the transmission device shown in FIG. The transmission bit sequence obtained at the input terminal 21 is temporarily stored in the memory 22, and the stored transmission bit sequence is supplied to the first preamble arrangement unit 23 and the second preamble arrangement unit 24.

The first preamble arranging section 23 is a circuit for arranging the first information (preamble signal) in the first mode (ie, the state shown in FIG. 2) between the second information. The second preamble arranging unit 24 is a circuit that arranges the first information (preamble signal) in the second mode (that is, the state shown in FIG. 8) between the second information.

Which one of the first preamble arranging unit 23 and the second preamble arranging unit 24 is used is controlled by the selecting unit 25, and the preamble signal is output by one of the preamble arranging units 23 and 24. The arranged transmission symbol stream is supplied to the modulator 26. The modulator 26 performs, for example, QPSK modulation,
The modulated data is supplied from a terminal 27 to an IFFT circuit (not shown).

In order to select a mode by the selection section 25, a signal obtained by determining a reception signal obtained at the terminal 28 by a circuit of the reception system 29 is supplied to the selection section 25. That is, on the receiving device side receiving the signal transmitted by the transmitting device of the present embodiment, when the first information (preamble signal) included in the transmission signal can be correctly detected, the first information is detected. Is transmitted by a transmission circuit (not shown). Then, when the reception system 29 shown in FIG. 4 determines that the detection data is included in the reception signal, the detection system supplies the detection data to the selection unit 25.

The mode selection operation in the selection unit 25 based on the detection data includes, for example, the first
, And the modulation section 26 modulates the output of the first preamble arranging section 23. Then, when the detection data is supplied from the reception system 29 to the selection unit 25 during a period from the start of the transmission until a predetermined time elapses, the transmission in the first mode is continued.
Then, when the above-described detection data is not supplied during a period from the start of transmission until a predetermined time elapses, the transmission mode is changed from the first mode to the second mode under the control of the selection unit 25. Then, the output of the second preamble arrangement unit 24 is modulated by the modulation unit 26.

Next, a description will be given of a processing configuration in a receiving apparatus that receives a signal processed and transmitted in this way. FIG.
Shows a configuration in which a preamble signal is detected by a detection circuit in the receiving device in this case. The circuit shown in FIG. 5 is incorporated in a circuit before performing Fourier transform, such as the window detection unit 204 in the receiving apparatus shown in FIG. When the reception sequence is obtained at the input terminal 31, the reception sequence is supplied to the mode selection unit 32. This mode selector 3
Reference numeral 2 denotes a circuit for switching the output of the input reception sequence to the first delay circuit 33 and the output to the second delay circuit 41 and the adder 42 to select a reception mode.

When the output of the mode selector 32 is supplied to the first delay circuit 33, the delay circuit 33 delays the input data by １ ／ modulation time (here, 80 μsec) and adds the delay output to the adder. 34 and performs an addition process with a signal that has not been delayed. By this addition processing, the adder 34
When the received signal is a signal transmitted in the state shown in FIG. 2, it functions as a comb filter that extracts only the preamble signal from the signal. The addition output of the adder 34 is supplied to a shift register 35.

The shift register 35 is a register in which data of 7 symbols is set. The shift register 35 compares the correlation with the preamble data of 7 symbols previously stored in the preamble buffer 36 by an individual multiplier 37a for each symbol. Take 37b 37g. Each multiplier 37a-
The output of the 37 g correlation value is supplied to the accumulator 51, and the power level for seven symbols is supplied to the accumulator 51.

When the output of the mode selector 32 is supplied to the second delay circuit 41 and the adder 42, the input data is halved by the second delay circuit 41 (here, 120 μm).
Second), and supplies the delayed output to the adder 42 to perform an addition process with a signal that has not been delayed. By this addition processing, when the received signal is a signal transmitted in the state shown in FIG. 8, the adder 42 functions as a comb filter that extracts only the preamble signal from the signal.
The addition output of the adder 42 is supplied to a shift register 43.

The shift register 43 is a register in which 11-symbol data is set. The shift register 43 compares the correlation with the 11-symbol preamble data stored in the preamble buffer 44 in advance by an individual multiplier 45a, Take 45b ‥‥ 45k. Each multiplier 45
The outputs of the correlation values of a to 45k are supplied to the accumulator 51,
The power level for 11 symbols is supplied to the accumulator 51.

The accumulator 51 includes multipliers 37a to 37g.
When the output of the correlation value is supplied, the cumulative addition process of the correlation value is performed, and when the output of the correlation value of the multipliers 45a to 45k is supplied, the cumulative addition process of the correlation value is performed. The cumulative addition value obtained by the cumulative adder 51 is supplied to the determination unit 52. The determination unit 52 performs a process of determining whether the cumulatively added power level is equal to or higher than a preset threshold level, and when determining that the power level is equal to or higher than the threshold level, outputs the determination output from the terminal 53 to the terminal It is supplied to a reception timing control means (a circuit corresponding to the time base controller 211 in FIG. 7) to control the processing timing in the FFT circuit or the like based on the determined timing.

A timer unit 54 started at the start of reception is connected to the determination unit 52. The mode selection unit 32 selects the first mode and outputs the correlation values of the multipliers 37a to 37n. When it is determined whether or not the threshold level is equal to or more than the threshold value from the accumulated addition value of the above, when it is determined that the threshold level is equal to or more than the threshold level until a predetermined time set in advance by the timer unit 54 elapses, Data for maintaining the reception mode in the mode selection unit 32 is supplied. When the receiving apparatus includes a transmission circuit, the data for maintaining the mode is output, and at the same time, the data indicating that the preamble signal can be detected is transmitted from the terminal 55 to the transmission circuit of the apparatus. And transmits data indicating that the preamble signal has been detected.

If it is not determined that the level is equal to or higher than the threshold level until the predetermined time set by the timer section 54 elapses, the reception mode selected by the mode selection section 32 is changed to the second mode. Supply data to be changed. Note that the predetermined time determined from the start of reception by the timer unit 54 is a time sufficient for detecting a preamble signal from the signal when the signal can be correctly received in the first mode (for example, one modulation time). (Time slightly longer than 1/3).

As described in the present embodiment, two modes are prepared as modes in which the preamble signal is arranged in the multicarrier signal on the transmitting side, and the first arrangement in which the arrangement intervals of the preamble signal are coarse at the start of transmission. Mode, and if transmission is good in the first mode,
If communication is performed in the same mode and communication is not possible in that mode, the second
In a good wireless communication environment, communication is performed with a small number of preamble signals, and in a poor wireless communication environment in which synchronization cannot be achieved in the first mode, the preamble is used. Communication is performed in the second mode in which the signal arrangement interval is narrow, and synchronization supplementation is easily performed. Therefore, an appropriate arrangement state of the preamble signal is automatically selected according to the communication environment at that time, and the synchronization for the Fourier transform processing of the multicarrier signal can be performed in any wireless environment. Supplementary processing is performed well.

In the present embodiment, a mode in which the first information, which is the preamble signal, is arranged every third of the second information, and the first information is arranged every other one of the second information. The communication is performed by preparing two modes, i.e., mode, but other arrangements may be used as long as the number of arrangements or the arrangement state of the preamble signals differs in each mode. For example, in the first mode, the first information, which is the preamble signal, is arranged every third of the second information, and in the second mode, the first information is arranged every other of the second information. You may do it.

Also, in the above-described embodiment, two modes are prepared and switched with respect to the number of modes of the arrangement state of the preamble signal prepared on the transmitting side.
Three or more modes may be prepared and an appropriate mode may be selected depending on the communication state at that time.

In the above-described embodiment, the delay circuits 33 and 41 are individually prepared for each mode in the preamble signal discriminating circuit of the receiving system shown in FIG.
The circuit configuration may be simplified by preparing only a set of circuits and changing the delay amount of the delay circuit in the one set of circuits to operate in a corresponding state. Further, in the configuration shown in FIG. 5, the adders 34 and 42 are used as circuits constituting the comb filter, but other circuits such as a subtracter may be configured to function as a similar filter. .

[0067]

According to the first aspect of the present invention, the first information, which is information necessary for acquiring synchronization, can be detected from the peak position of the correlation value detected by the correlator. The synchronization can be easily and accurately detected by the peak position.

According to the multi-carrier signal receiving apparatus described in claim 2, in the invention described in claim 1, the synchronization information stored by the synchronization information storage means is a known information pattern. Can be used to easily detect synchronization.

According to the multi-carrier signal transmitting apparatus according to the third aspect, the first information, which is information necessary for acquiring synchronization, is transmitted at a predetermined regular interval between the second information and the transmission symbol stream. Can be generated, the transmission symbol stream can be modulated and transmitted as a multicarrier signal, and a signal in which information necessary for acquiring synchronization is arranged at an arbitrary interval can be transmitted.

According to the multi-carrier signal transmitting device described in claim 4, in the invention described in claim 3, the notification regarding the synchronization detection from the side receiving the signal modulated by the modulation means is transmitted for a predetermined time from the start of transmission. If not, the selection unit changes the interval of the first information of the transmission symbol stream generated by the transmission symbol stream generation unit from the first interval to the second interval, thereby providing the first information. By changing the interval, it is possible to set so that synchronization detection can be easily performed on the receiving side, and perform processing so that communication can be performed well.

According to the multi-carrier signal transmitting apparatus described in claim 5, in the invention described in claim 4, the first interval is such that one piece of first information is equal to two or more pieces of second information. The second interval is an interval that is alternately arranged, and the second interval is an interval that is alternately arranged every other piece of the first information and the second information. , The synchronization can be easily detected on the receiving side.

According to the multi-carrier signal receiving apparatus of the present invention, when the reception is performed in one of the reception modes and the synchronization cannot be detected from the correlation between the received symbol stream and the stored synchronization data by the correlator, the reception is performed. By changing the mode and changing the amount of delay in the delay means and the synchronization data for performing correlation detection, synchronization can be detected regardless of the mode of the transmitted multicarrier signal.

According to the multi-carrier signal receiving apparatus described in claim 7, in the invention described in claim 6, the first of the plurality of modes set by the reception mode setting means is set.
Is a mode in which one first information receives a symbol stream interleaved with two or more pieces of second information, and the second mode is a mode in which the first information and the second information are mixed.
Is a mode in which a symbol stream in which every other information is alternately arranged is received, so that a symbol stream in each arrangement can be received satisfactorily.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a preamble signal detection configuration according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration example of transmission data according to the first embodiment of the present invention.

FIG. 3 is a waveform chart showing a phase of a filter output according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating an example of a transmission configuration according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating an example of a preamble signal detection configuration according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating an example of a configuration of transmitting a multicarrier signal.

FIG. 7 is a block diagram illustrating an example of a configuration for receiving a multicarrier signal.

FIG. 8 is an explanatory diagram showing an example of a transmission data configuration proposed earlier.

9 is a configuration diagram illustrating an example of a data detection configuration illustrated in FIG. 8;

FIG. 10 is a waveform chart showing an example of the phase of a received symbol.

FIG. 11 is a waveform diagram showing an example of the phase of a preamble signal included in a received signal.

[Explanation of symbols]

12 delay circuit, 13 adder, 14 shift register, 15 preamble buffer, 16a to 16g multiplier, 17 cumulative accumulator, 18 decision unit, 22 memory, 23 first preamble placement unit , 24 ... second preamble arranging unit, 25 ... selecting unit, 26 ... modulating unit, 29
... Receiving unit, 32 ... Mode selecting unit, 33 ... Delay circuit, 34
... adder, 35 ... shift register, 36 ... preamble buffer, 37a-37k ... multiplier, 41 ... delay circuit,
42 adder, 43 shift register, 44 preamble buffer, 45a to 45g multiplier, 51 accumulator, 52 decision unit, 54 timer unit

Claims (7)

[Claims] 1. A signal in which first information necessary for obtaining synchronization of a transmission signal is arranged at regular intervals between second information which is other information, and a signal transmitted as a multicarrier signal. In the multi-carrier signal receiving apparatus, when the predetermined interval is n symbols, one modulation time /
Delay means for delaying the received symbol stream by the time of (n + 1); received symbol stream delayed by the delay means;
A filter unit that extracts the first information using a received symbol stream that is not delayed; a synchronization data storage unit that stores synchronization data to be received; an output of the filter unit and the synchronization information storage unit A multicarrier signal receiving apparatus comprising: a correlator for correlating with accumulated synchronization data; and a determination unit for performing synchronization detection based on a peak position of a correlation value of the correlator. 2. The multicarrier signal receiving apparatus according to claim 1, wherein the synchronization information stored by said synchronization information storage means is a known information pattern. 3. A multicarrier for transmitting, as a multicarrier signal, a signal in which first information necessary for obtaining synchronization of a transmission signal is arranged at regular intervals between second information serving as other information. In the signal transmission device, interleaving means for rearranging the coded bit sequence, bit sequence storage means for storing the bit sequence rearranged by the interleaving means, and the first information between the second information Transmission symbol stream generating means arranged at predetermined intervals, selecting means for setting the predetermined interval at which the transmission symbol stream generating means arranges the first information, transmission transmitted by the transmission symbol stream generating means A multicarrier signal transmission device comprising: a modulation unit that modulates a symbol stream. 4. The multi-carrier signal transmitting apparatus according to claim 3, wherein when there is no notification of synchronization detection from a side receiving the signal modulated by the modulation unit for a predetermined time or more from the start of transmission, the selection unit is configured to: A multi-carrier signal transmission apparatus for changing an interval of the first information of the transmission symbol stream generated by the transmission symbol stream generation unit from a first interval to a second interval. 5. The multicarrier signal transmitting apparatus according to claim 4, wherein the first interval is an interval in which one piece of first information is alternately arranged with two or more pieces of second information. The multicarrier signal transmission device, wherein the second interval is an interval in which the first information is alternately arranged with the second information every other interval. 6. A signal in which first information necessary for acquiring synchronization of a transmission signal is arranged at regular intervals between second information, which is other information, and a signal transmitted as a multicarrier signal. In a multi-carrier signal receiving apparatus for receiving a signal, a reception mode setting means for setting a reception mode, a delay means for variably setting a delay amount by the reception mode setting means, a reception symbol stream delayed by the delay means,
A filter unit for extracting the first information using a received symbol stream that has not been delayed; a plurality of types of synchronization data to be received that are stored; and synchronization data corresponding to a mode set by the reception mode setting unit. A synchronous data accumulating means for outputting a signal; a correlator for correlating the output of the filter unit with the synchronous data accumulated and output by the synchronous information accumulating means; and a synchronous detection based on a peak position of a correlation value of the correlator. A multicarrier signal receiving apparatus, comprising: a determination unit that performs the detection; and a control unit that changes a reception mode set by the reception mode setting unit when synchronization cannot be detected by the determination unit. 7. The multi-carrier signal receiving apparatus according to claim 6, wherein the first mode among the plurality of modes set by the reception mode setting means includes one or more pieces of first information. A mode in which a symbol stream alternately arranged with the second information is received. The second mode is a mode in which a symbol stream in which the first information and the second information are alternately arranged every other is used. A multi-carrier signal receiving device in a receiving mode.