JP2012199750A - Wireless transmitter and wireless receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to improvement of estimation accuracy of a propagation path without sacrifice of throughput of data transfer in communication technology by OFDM.SOLUTION: In a plurality of symbols (SMBL) constituting a slot (SLT_adv), a series of known signals (SIGDIV_ref) for estimating the propagation path of wireless communication is arranged in regions α, β while being divided. In other words, a symbol is generated by combining an information signal and the known signal and arranged in a slot. Since a series of known signals assigned to one symbol is arranged in each symbol while being distributed, the propagation path can be estimated in units of symbol. Followability of propagation path estimation is improved by estimating the propagation path in units of symbol.

Description

  The present invention relates to a wireless transmission device, a wireless reception device, and a wireless communication device using OFDM (Orthogonal Frequency Division Multiplexing) technology. For example, the present invention relates to a mobile communication system and further to a technology effective when applied to a mobile communication terminal.

  The OFDM technology is used in many systems such as LTE (Long Term Evolution) in 3GPP (Third Generation Partnership Project). In mobile communication, information is transmitted using the phase and amplitude of radio waves. However, since mobile communication terminals move, the phase and frequency of radio waves change from moment to moment. It is necessary to improve reception performance. For propagation path estimation, a known reference signal is included in a transmission slot and transmitted by a receiving device, and a component of the received wave in the time domain is analyzed with respect to the transmitted reference signal to extract a known signal. A technique for estimating the arrival time and amplitude of the plurality of reflected waves is used. Conventionally, a cyclic prefix (hereinafter also simply referred to as CP) as a guard band has been used in the OFDM technique in order to maintain orthogonality between subcarriers in a multipath environment.

  A communication frame structure used in a system such as LTE has, for example, one frame of 10 ms, and each 0.5 ms slot includes 19 slots, and each slot is composed of a plurality of symbols. A reference signal having a length of 1 symbol per slot is added to an uplink signal from the terminal to the base station, and a CP is added to each symbol of the data signal before the payload. In addition, there exists the following nonpatent literature 1 as an example of the literature described about LTE.

Long Term Evolution (LTE): Overview of LTE Air-Interface Technical White Paper http://business.motorola.com/experiencelte/pdf/LTEAirInterfaceWhitePaper.pdf

  However, the conventional reference signal has a constant bit length such as one symbol length per slot. In order to improve the estimation accuracy (synchronization detection accuracy) of the propagation path, it is conceivable to increase the number of symbols of the reference signal. However, if this is done, the data length of the payload in the slot or frame will be shortened and the data transmission efficiency will be reduced Throughput is sacrificed.

  An object of the present invention is to contribute to improvement of propagation path estimation accuracy without sacrificing data transmission throughput in OFDM communication technology.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  That is, a sequence of known signals for estimating a radio communication propagation path is divided and arranged in a plurality of symbols constituting a slot. In other words, a symbol obtained by combining the information signal and the known signal is generated and placed in the slot.

  As a result, since a sequence of known signals assigned to one symbol is distributed and arranged in each symbol, the radio reception apparatus can estimate a propagation path in symbol units. By performing propagation path estimation on a symbol basis, the followability of transmission path estimation is improved.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  In other words, it is possible to contribute to improvement of propagation path estimation accuracy without sacrificing data transmission throughput in the communication technology using OFDM.

FIG. 1 is an explanatory diagram of a slot format in which reference signals are aggregated and arranged in one symbol and a slot format in which a reference signal is divided into symbols. FIG. 2 is a block diagram illustrating a radio transmission apparatus according to the first embodiment of the invention. FIG. 3 is a block diagram illustrating a wireless reception device that receives and processes a signal transmitted from the wireless transmission device of FIG. FIG. 4 is a block diagram illustrating a wireless transmission device that varies the bit length of the reference signal according to the wireless communication state. FIG. 5 is a flowchart illustrating the β value calculation and selection function by the calculator and the selector. FIG. 6 is a block diagram illustrating a wireless reception device that receives and processes a signal transmitted from the wireless transmission device of FIG.

1. First, an outline of a typical embodiment of the invention disclosed in the present application will be described. Reference numerals in the drawings referred to in parentheses in the outline description of the representative embodiments merely exemplify what are included in the concept of the components to which the reference numerals are attached.

[1] <Divided arrangement of known signal sequences in a plurality of symbols>
A wireless transmission apparatus that performs wireless communication using an OFDM scheme according to a representative embodiment of the present invention includes a sequence of known signals for determining a propagation path of wireless communication and an information signal obtained by modulating information to be transmitted. A slot generator that generates slots by arranging the symbols in a plurality of symbols having a predetermined symbol length, and an OFDM signal in the time domain by performing inverse Fourier transform on the symbols arranged in the slots generated by the slot generator And a radio transmission unit that modulates the OFDM signal generated by the inverse Fourier transform processing unit into a predetermined radio communication frequency band and transmits the modulated signal as an RF signal. The slot generator divides and arranges the sequence of known signals into each symbol.

  As a result, since a sequence of known signals assigned to one symbol is distributed and arranged in each symbol, the throughput of the information signal when viewed in slot units does not decrease, and the radio receiving apparatus estimates the propagation path in symbol units. It becomes possible to do. Compared with the case where a sequence of known signals is arranged in one symbol, the bit length of the known signal for each symbol is shorter and the correlation due to propagation path estimation obtained for each symbol is smaller, but the propagation path of each symbol is reduced. By performing the estimation, the followability of the transmission path estimation is improved. Therefore, it is possible to contribute to improving the estimation accuracy of the propagation path without reducing the throughput.

[2] <Cyclic prefix area and postfix area in the symbol are known signals>
In the wireless transmission device according to Item 1, the region where the known signal sequence is divided and arranged is a cyclic prefix region arranged at the head of the symbol and a region arranged at the rear end of the symbol.

  By using not only the area arranged at the rear end of the symbol but also the cyclic prefix area for the arrangement of the known signal, the number of bits of the known signal when viewed in symbol units increases, and the follow-up performance of the transmission path estimation However, the area of the cyclic prefix diverted to the arrangement of known signals can still function as a guard band. However, in this case, the cyclic prefix cannot be formed by copying the end of the information signal.

[3] <Data processing unit for generating a sequence of known signals and information to be transmitted>
The wireless transmission device according to Item 2 includes a data processing unit that generates the known signal sequence and the information signal and supplies the information signal to the slot generation unit.

  The slot and symbol format can be easily controlled by the control of the data processing unit.

[4] <Variable control of bit length of known signal>
4. The wireless communication device according to item 3, wherein the data processing unit variably sets the bit length of the known signal according to a predetermined rule that shortens the bit length as the wireless communication state of the propagation path is better. Supply.

  When the wireless communication state is good, it is possible to estimate a good transmission path with a small number of bits of the known signal. In this case, priority is given to improving the transmission throughput of the information signal by reducing the number of bits of the known signal. it can.

[5] <Control bit length of known signal according to reception sensitivity>
The wireless transmission device according to item 4 includes a reception sensitivity detection unit, and the data processing unit sets the bit length of the known signal according to the reception sensitivity of the detection unit.

  It is possible to contribute to stabilization of wireless communication by dynamically controlling the followability of the transmission path estimation and the transmission throughput of the information signal.

[6] <The rear end area of the symbol is the variable length area of the known signal>
In the wireless communication device according to Item 5, the data processing unit controls a region arranged at a rear end portion of the symbol among regions where the known signal is arranged as a variable bit length target.

  The cyclic prefix area format for symbols can be kept constant to increase compatibility with other slot formats.

[7] <Postfix area in symbol is known signal>
In the wireless communication device according to Item 1, the region where the known signal series is divided and arranged is a region arranged at the rear end of each symbol.

  Although it is slightly inferior to item 2 in terms of improving the follow-up performance of transmission path estimation, the symbol format constituting the cyclic prefix can be maintained by the copy at the end of the information signal and has such a cyclic prefix. Compatibility with other slot formats can be increased.

[8] <Radio receiving apparatus that processes symbols in which known signals are divided and arranged>
According to another embodiment of the present invention, there is provided a radio reception apparatus that performs radio communication using the OFDM method, a radio reception unit that converts an RF signal transmitted from the radio transmission apparatus according to Item 1 into a baseband signal, and the radio A Fourier transform unit that performs Fourier transform on the baseband signal transformed by the receiving unit to generate a symbol in the frequency domain, and an extraction unit that extracts a known signal and an information signal contained in the symbol transformed by the Fourier transform unit And having.

  A radio reception apparatus applied to a base station of a mobile communication system uses a received known signal, so that a propagation path can be used even when the position of the radio transmission apparatus applied to a mobile communication terminal changes from moment to moment. Wireless communication can be performed with improved estimation accuracy.

[9] <Radio receiving apparatus corresponding to variable bit length of known signal>
A radio reception apparatus that performs radio communication using an OFDM scheme according to still another embodiment of the present invention includes: a radio reception unit that converts an RF signal transmitted from the radio transmission apparatus according to Item 5 into a baseband signal; A Fourier transform unit that generates a frequency-domain symbol by performing a Fourier transform on the baseband signal converted by the wireless reception unit, and an extraction that extracts a known signal and an information signal included in the symbol converted by the Fourier transform unit The extraction unit acquires the bit length of the known signal determined by the wireless transmission device, and extracts the known signal from the symbol according to the acquired bit length.

  A radio reception apparatus applied to a base station of a mobile communication system obtains the number of bits of a known signal transmitted by a radio transmission apparatus applied to a mobile communication terminal or the like with a bit number corresponding to a communication state. Therefore, a known signal can be easily obtained from the transmitted symbol.

2. Details of Embodiments Embodiments will be further described in detail.

Embodiment 1
FIG. 2 illustrates a radio transmission apparatus according to the first embodiment of the present invention. The wireless transmission device 1 shown in the figure performs OFDM wireless communication and is applied to a mobile communication terminal such as a mobile phone used in a mobile communication system. That is, the wireless transmission device 1 is used for uplink transmission. The wireless transmission device 1 includes a data processing unit 2, a slot generation unit 3, an inverse Fourier transform processing unit (IFFT processing unit) 4, a band modulation unit 5 as a wireless transmission unit, and an antenna 6.

  The slot generation unit 3 generates a slot by arranging a sequence of known signals for determining a radio communication propagation path and an information signal obtained by modulating information to be transmitted in a plurality of symbols having a predetermined symbol length.

  The inverse Fourier transform processing unit 4 performs an inverse Fourier transform on the symbols arranged in the slots generated by the slot generation unit 3 to generate a time domain OFDM signal.

  The band modulation unit 5 modulates the OFDM signal generated by the inverse Fourier transform processing unit 4 into a predetermined radio communication frequency band, and transmits it from the antenna 5 as an RF signal.

  The data processing unit 2 generates the known signal series and the information signal, and supplies them to the slot generation unit 3. The data processing unit 2 is realized by a processor as a program processing device, an accelerator, and its peripheral circuits, and is applied to communication protocol processing for a mobile communication terminal, display control for a mobile communication terminal, and the like. The information signal generator 20 generates transmission data that constitutes the payload. The known signal generation unit 21 generates a reference signal as a known signal that is known in the base station of the mobile communication system.

  An example of a slot format conventionally used in radio communication by OFDM is SLT_prv in FIG. The slot SLT_prv of this format is not particularly limited, but one symbol SMBL constitutes one slot, and one symbol SMBL includes a payload x as an information signal and a cyclic prefix CP as a guard band. Have. In the case of 3GPP LTE, the cyclic prefix CP has 160 bits for the first symbol SMBL corresponding to 1st, 144 bits for the other cyclic prefix CP, and 2048 bits for the payload x. At this time, the reference signal SIG_ref is arranged in one symbol SMBL. The reference signal SIG_ref is a known signal at the receiving base station, and the base station estimates the arrival time and amplitude of the plurality of reflected waves based on the signal extracted from the received wave of the received reference signal SIG_ref. Estimate

  On the other hand, the slot generated by the slot generation unit 3 has a format indicated by SLT_adv in FIG. That is, the slot SLT_adv has a format in which a series of reference signals is divided and arranged in each symbol SMBL in the slot. SIGDIV_ref is a divided reference signal. Each SIGDIV_ref is also a known signal in the receiving base station, and the base station estimates the arrival time and amplitude of the plurality of reflected waves based on the signal extracted from the received wave of the received reference signal SIGDIV_ref. Estimate In this case, a symbol of only the reference signal SIG_ref as shown in the slot SLT_prv is not necessary.

  The area where the divided reference signal SIGDIV_ref is arranged can be a first arrangement form using both areas α and β in each symbol SMBL, or a second arrangement form using only the region β in each symbol SMBL. The region α is a region of the cyclic prefix CP as a guard band in the conventional slot format SLT_prv, and is a region provided at the head of the symbol SMBL. The region β is a region provided at the rear end portion of the symbol SMBL. At this time, the payload is set to y.

  In either the first arrangement form or the second arrangement form, the sequence of the reference signal SIGDIV_refh assigned to one symbol is dispersedly arranged in each symbol, so that the transmission throughput of payloadons when viewed in slot units is reduced. Therefore, it is possible to estimate the propagation path in symbol units. Compared with the case where a sequence of known signals is arranged in one symbol, the bit length of the known signal for each symbol is shorter and the correlation due to propagation path estimation obtained for each symbol is smaller, but the propagation path of each symbol is reduced. By performing the estimation, the followability of the transmission path estimation is improved. Therefore, it is possible to contribute to improving the estimation accuracy of the propagation path without reducing the throughput.

  In particular, in the first arrangement form, not only the region β arranged at the rear end of the symbol but also the cyclic prefix region α is used for the arrangement of the reference signal SIGDIV_ref, so that the reference signal SIGDIV_ref when viewed in symbol units is used. Since the number of bits increases, the followability of the transmission path estimation is further improved, and the cyclic prefix area α diverted to the arrangement of the reference signal SIGDIV_ref can still maintain its function as a guard band. However, in this case, the cyclic prefix CP cannot be formed by copying the end of the information signal.

  In the second arrangement form, although it is slightly inferior to the first arrangement form in terms of improving the follow-up performance of the transmission path estimation, the symbol format constituting the cyclic prefix CP can be maintained by the copy at the end of the payload, It becomes possible to increase compatibility with other slot formats having such a cyclic prefix CP.

The number of bits of the reference signal SIGDIV_ref when the first arrangement form is adopted will be specifically described. For example, the CP in the 1st symbol SMBL is 160 samples, the CP in the 2nd to 7th symbols SMBL is 144 samples, and the payload length is 2048 samples. This definition is as follows:
CP (1 ^st ) = 160 samples
CP (2 ^{nd 〜} 7 ^th ) = 144 samples
The length of payload = 2048 samples
Write like this. Note that one sample is equivalent to 1 bit, for example.

In the slot format SLT_prv of FIG. 1, the ratio (Reference samples / Total samples) of the number of bits of the reference signal (energy) to the number of bits (energy) of the entire slot, and the number of bits of the payload (energy) is the number of bits of the entire slot. The ratio (Payload samples / Total samples) in (energy) relates to the total number of samples in the slot SLT_prv (Total samples), the total number of samples of the reference signal SIG_ref (Reference samples), and the total number of payload samples (Payload samples). The following formula,
Total samples = 15360 samples
Reference samples = 2048 + 144 = 2192 samples
Payload samples = 2048 * 6 = 12288 samples
By
∴Reference samples / Total samples = 2192/15360 = 14.27%
∴Payload samples / Total samples = 12288/15360 = 80%
It is estimated.

On the other hand, when the sequence of the reference signal SIGDIV_ref is divided and arranged in the regions α and β in the slot format SLT_adv of FIG. / Total samples) and the ratio of the number of bits (energy) of the payload to the number of bits (energy) of the entire slot (Payload samples / Total samples) is equivalent to the above-mentioned 12288 samples (12288/7 = 1756 ) Subject to the following formula:
Total samples = 15360 samples
Reference samples = (2048-1756) * 7 + (160 + 144 * 6) = 2044 + 1024 = 3068 samples
Payload samples = 1756 * 7 = 12292 samples
By
∴Reference samples / total samples = 3068/15360 = 19.96%
∴Payload samples / Total samples = 12292/15360 = 80.03%
It is estimated.

  As a result, when viewed in slot units, the number of bits of the sequence of the reference signal SIGDIV_ref in the slot SLT_adv is increased by 5.69% than the number of bits of the reference signal SIG_ref in the slot SLT_prv. At this time, the data transmission throughput in the slot SLT_adv at least maintains the data transmission throughput in the slot SLT_prv. Therefore, by adopting the format of the slot SLT_adv, the energy (number of bits) of the reference signal can be increased without causing deterioration of the output to be transmitted. Improvement can be expected. As the propagation path changes from moment to moment, the accuracy of synchronization detection and the follow-up performance of transmission path estimation can be easily increased, contributing to the reduction of the cost of parts used to configure the wireless receiver. .

  FIG. 3 illustrates a wireless reception device that receives and processes a signal transmitted from the wireless transmission device 1 of FIG. A radio reception apparatus 11 shown in the figure performs radio communication by OFDM, and is applied to, for example, a base station used in a mobile communication system, and is used for radio reception in uplink transmission. The wireless reception device 11 includes an antenna 12, a band demodulation unit 13 as a wireless reception unit, a Fourier transform unit (FFT processing unit) 14, an extraction unit 15, and a data processing unit 16.

  The band demodulator 13 receives the RF signal transmitted from the wireless transmission device 1 shown in FIG. 2 by the antenna 12 and converts it into a baseband signal. The Fourier transform unit 14 performs a Fourier transform on the baseband signal converted by the band demodulation unit 13 to generate a frequency domain symbol. The extraction unit 15 extracts a known signal and an information signal included in the symbol converted by the Fourier transform unit 14. The data processing unit 16 estimates the transmission path using the extracted known signal, and controls a reception operation suitable for the estimated transmission path. Predetermined data processing is performed on the received information signal. Even when the position of the wireless transmission device 1 applied to a mobile communication terminal or the like changes every moment by using the received known signal, the wireless reception device 11 applied to a base station of the mobile communication system or the like. Wireless communication can be performed with improved estimation accuracy of the propagation path.

<< Embodiment 2 >>
FIG. 4 illustrates a wireless transmission device 1A that changes the bit length of a known signal in accordance with the wireless communication state. The difference from the wireless transmission device 1 of FIG. 2 described in the first embodiment is that the bit length of the known signal generated by the data processing unit 2A is variably controlled. Other configurations are the same as those in the case of FIG. 2 of the first embodiment, and functional blocks having the same functions are denoted by the same reference numerals, and detailed description thereof is omitted.

  The data processing unit 2A variably sets the bit length of the reference signal SIGDIV_ref as a known signal according to a predetermined rule that shortens the bit length as the wireless communication state of the propagation path is better, and supplies the reference signal SIGDIV_ref to the slot generation unit 3 . Here, although not particularly limited, the data processing unit 2A sets the maximum bit length of the region β arranged at the rear end of the symbol as a variable bit length, and the region α is subject to variable bit length. Shall not. This is to increase the compatibility with the slot format in which the cyclic prefix CP of the symbol is provided in the region α with a specified bit length.

  In order to variably control the bit length of the region β, a reception level detection unit 7 that detects the wireless communication state of the transmission path based on the electric field strength of the reception signal is provided, and the data processing unit 2A receives the detection level RSSI. The data processing unit 2A includes a register 22 in which a specified number of bits in the region β is set, and a calculation unit 23 that calculates the number of bits in the region β according to the detection level, and the number of bits calculated by the calculation unit 23 The selector 24 selects the value or the value of the number of bits held in the register 22 according to the detection level RSSI, and supplies the selected value to the information signal generator 20 and the known signal generator 21. Hereinafter, the number of bits allocated to the region β is also simply referred to as β value. Although not particularly limited, the β value assigned to the region β is assumed to be three levels: large, medium, and small. The β value of the prescribed number of bits held by the register 22 is the number of bits in the middle stage. The computing unit 23 computes the large number of bits or the small number of bits according to the detection level RSSI. The selector 24 selects the output of the register 22 or the output of the calculation unit 23 according to the detection level RSSI.

  The known signal generation unit 21 generates the reference signal SIGDIV_ref with the number of bits determined by the number of bits corresponding to the β value supplied from the selector 24 and the prescribed number of bits in the region α.

  The information signal generator 20 generates a payload information signal with the number of bits determined by the number of bits indicated by the β value and the number of bits in the region α.

  The β value calculation and selection function by the calculation unit 23 and the selector 24 will be described with reference to FIG. The reception level detection unit 7 generates a detection level RSSI by performing a simple moving average or a weighted moving average on a plurality of latest detection values detected at a predetermined interval (S1). The calculation unit 23 calculates a large β value when the detection level RSSI is smaller than the predetermined threshold LVth1 (S2), and conversely calculates a small β value when the detection level RSSI is larger than the predetermined threshold LVth2 ( S3) In any case, the selector 24 selects and outputs the output of the calculation unit 23 (S2, S3). On the other hand, when the detection level RSSI is equal to or higher than the predetermined threshold LVth1 or lower than the threshold LVth2, the calculation unit 23 stops the β value calculation, and the selector 24 selects and outputs the specified β value of the register 22 (S4).

  By variably controlling the bit length (β value) of the region β, the transmission path can be estimated with a small number of bits of the reference signal SIGDIV_ref when the wireless communication state is good. In this case, the number of bits of the reference signal SIGDIV_ref Therefore, priority can be given to improving the transmission throughput of the information signal. Conversely, when the wireless communication state is poor, the transmission path estimation accuracy can be improved with a large number of bits of the reference signal SIGDIV_ref. In particular, it is possible to contribute to stabilization of wireless communication by dynamically controlling the followability of transmission path estimation and the transmission throughput of information signals.

  FIG. 6 illustrates a wireless reception device 11A that receives and processes a signal transmitted from the wireless transmission device 1A of FIG. The difference from the wireless transmission device 1 of FIG. 3 described in the first embodiment is that the extraction unit 15A acquires the bit length of the reference signal SIGDIV_ref determined by the wireless transmission device 1A, and from the symbol according to the acquired bit length. It is to extract a known signal. For example, the reception level detected by the wireless transmission device 1A is detected by the reception level detection unit 17 and given to the extraction unit 15A. The reception level detection unit 17 is not particularly limited, but has the same configuration as the reception level detection unit 7, detects the reception level when receiving the transmission signal from the wireless transmission device 1A, and generates a β value according to the detection level. The generated β value is given to the extraction unit 15A. Accordingly, the extraction unit 15A acquires the bit length of the reference signal SIGDIV_ref. Other configurations are the same as those in the case of FIG. 3 of the first embodiment, and functional blocks having the same functions are denoted by the same reference numerals, and detailed description thereof is omitted.

  The radio reception device 11A applied to a base station of a mobile communication system uses the number of bits of the reference signal SIGDSIV_ref transmitted by the radio transmission device 1A applied to a mobile communication terminal or the like with the number of bits corresponding to the communication state. Since it can be acquired, the reference signal SIGDSIV_ref can be easily acquired from the transmitted symbol.

  In a mobile communication system using the wireless transmission device 1A and the wireless reception device 11A, in an unfavorable propagation path, when the β value is decreased to improve the throughput, the accuracy of synchronization establishment is reduced by the reference signal SIGDIV_ref, and reception is performed correctly. I can't do it. In such a case, the correlation value is improved by increasing the β value, and synchronization tolerance between the mobile communication terminal to which the wireless transmission device 1A is applied and the base station to which the wireless reception device 11A is applied is improved. Can strengthen. Conventionally, the transmission path is estimated for each slot, but since the transmission path can be estimated for each symbol, it is possible to accurately follow the change of the propagation path. As a result, the propagation path estimation accuracy can be increased as compared with the conventional case. On the contrary, in a static propagation path, throughput can be improved by reducing β.

  Although the invention made by the present inventor has been specifically described based on the embodiments, it is needless to say that the present invention is not limited thereto and can be variously modified without departing from the gist thereof.

  For example, the wireless transmission device is not limited to being applied to a mobile communication terminal, and can also be applied to a base station of a mobile communication system. Similarly, the radio reception apparatus is not limited to being applied to a base station of a mobile communication system, and can be applied to a mobile communication terminal.

  Needless to say, communication frames, slots, and symbols for wireless communication using OFDM can be changed as appropriate according to the communication scheme or communication protocol to which the present invention is applied.

DESCRIPTION OF SYMBOLS 1 Wireless transmitter 2 Data processing part 3 Slot production | generation part 4 Inverse Fourier-transform processing part (IFFT process part)
5 Band Modulation Unit 6 Antenna 20 Information Signal Generation Unit 21 Known Signal Generation Unit SLT_adv Slot Format SMBL Symbol SIG_ref Reference Signal SIGDIV_ref Divided Reference Signal 11 Radio Receiver 12 Antenna 13 Band Demodulation Unit 14 Fourier Transform Unit (FFT Processing Unit)
DESCRIPTION OF SYMBOLS 15 Extraction part 16 Data processing part 1A Wireless transmitter 2A Data processing part 22 Register 22
23 arithmetic unit 24 selector RSSI detection level 11A wireless receiver 15A extraction unit 17 reception level detection unit

Claims (9)

A wireless transmission device that performs wireless communication by OFDM,
A slot generation unit that generates a slot by arranging a sequence of known signals for determining a propagation path of wireless communication and an information signal obtained by modulating information to be transmitted in a plurality of symbols having a predetermined symbol length;
An inverse Fourier transform processing unit that performs an inverse Fourier transform on the symbols arranged in the slots generated by the slot generation unit to generate a time-domain OFDM signal;
A wireless transmission unit that modulates the OFDM signal generated by the inverse Fourier transform processing unit into a predetermined wireless communication frequency band and transmits it as an RF signal;
The slot generation unit is a wireless transmission apparatus that divides and arranges the sequence of known signals into respective symbols.   2. The radio transmission apparatus according to claim 1, wherein the area where the known signal sequence is divided and arranged is a cyclic prefix area arranged at a head of the symbol and an area arranged at a rear end portion of the symbol.   The radio transmission apparatus according to claim 2, further comprising a data processing unit that generates the series of known signals and the information signal and supplies the information signal to the slot generation unit.   4. The data processing unit according to claim 3, wherein the bit length of the known signal is variably set and supplied to the slot generation unit according to a predetermined rule that shortens the bit length as the wireless communication state of the propagation path is better. Wireless transmission device. It has a detection unit for reception sensitivity,
The wireless transmission device according to claim 4, wherein the data processing unit sets a bit length of the known signal in accordance with reception sensitivity of the detection unit.   The radio transmission apparatus according to claim 5, wherein the data processing unit controls a region arranged at a rear end portion of the symbol among regions where the known signal is arranged as a variable bit length target.   The radio transmission apparatus according to claim 1, wherein the area where the sequence of known signals is divided is an area arranged at a rear end portion of each symbol. A wireless receiver that performs wireless communication using an OFDM method,
A radio reception unit that converts an RF signal transmitted from the radio transmission device according to claim 1 into a baseband signal;
A Fourier transform unit that performs a Fourier transform on the baseband signal transformed by the wireless reception unit to generate a symbol in the frequency domain;
A radio receiving apparatus comprising: a known signal included in a symbol transformed by a Fourier transform unit; and an extraction unit that extracts an information signal. A wireless receiver that performs wireless communication using an OFDM method,
A radio reception unit that converts an RF signal transmitted from the radio transmission device according to claim 5 into a baseband signal;
A Fourier transform unit that performs a Fourier transform on the baseband signal transformed by the wireless reception unit to generate a symbol in the frequency domain;
An extraction unit for extracting a known signal and an information signal included in the symbol transformed by the Fourier transform unit;
The extraction unit is a wireless reception device that acquires a bit length of the known signal determined by the wireless transmission device and extracts a known signal from a symbol according to the acquired bit length.

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