JP6585537B2 - TRANSMISSION DEVICE, TRANSMISSION METHOD, SYSTEM, COMMUNICATION DEVICE, AND COMMUNICATION METHOD - Google Patents

Description

  The present invention relates to a transmission device, a transmission method, a system, a communication device, and a communication method.

  In Long Term Evolution (LTE), which is currently in widespread use, OFDM (Orthogonal Frequency Division Multiplexing) is employed. In OFDM, by providing a guard interval called a cyclic prefix (Cyclic-Prefix) at the beginning of each OFDM symbol, inter-symbol interference (hereinafter referred to as Inter-Symbol Interference, hereinafter) that the delayed wave of the previous OFDM symbol affects the next OFDM symbol. It is possible to reduce or eliminate interference between subcarriers caused by the collapse of orthogonality between subcarriers (referred to as ISI).

  However, the cyclic prefix is a section in which data transmission cannot be performed substantially, and can be a source of interference with adjacent symbols or other signals. In contrast, Non-Patent Document 1 describes some of the beginning and end of a symbol (in the time domain) included in an input sequence to a DFT of a transmission system in a DFTS (Discrete Fourier Transform Spread) -OFDM signal. A technique for reducing the intensity of the tail of the output time signal by setting “0” is disclosed. By keeping the tail intensity sufficiently small, it is expected that interference with adjacent symbols or other signals is sufficiently small in the time range corresponding to the tail.

G. Berardinelli, F. Tavares, T. Sorensen, P. Mogensen, and K. Pajukoski, "Zero-tail dft-spread-ofdm signals," in Globecom Workshops (GC Wk-shps), 2013 IEEE, Dec 2013, pp 229-234.

  In DFTS-OFDM, pilot symbols for channel estimation are usually inserted in frequency domain processing after DFT. However, when the technique described in Non-Patent Document 1 is employed, if such a pilot symbol is inserted, a decrease in the tail strength of the output time signal cannot be guaranteed.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a communication technique that can achieve both reduction in intensity of a predetermined portion of an output time signal and channel estimation using a pilot signal.

  One embodiment of the present invention relates to a transmission device. This transmitting apparatus converts a time-domain input symbol sequence into frequency-domain frequency data, and converts the frequency data obtained by the conversion into a time-domain data signal having a desired frequency band and having a predetermined portion intensity. A conversion unit that converts the data signal in a time domain smaller than the intensity of the other part; and an addition unit that adds a time domain pilot signal for channel estimation to a predetermined part of the data signal.

  Another aspect of the present invention is a system. The system includes a transmission device and a reception device that communicates wirelessly with the transmission device, and the transmission device converts an input symbol sequence in the time domain into frequency data in the frequency domain, and the frequency data obtained by the conversion A time domain data signal having a desired frequency band and converting a predetermined part intensity to a time domain data signal smaller than the intensity of the other part, and a time domain pilot for channel estimation An adder that adds the signal to a predetermined portion of the data signal, and the receiving device demodulates the radio frequency signal modulated by the signal output from the adder of the transmitter, and the demodulation by the demodulator Of the signals obtained as a result of the above, a portion corresponding to a predetermined portion of the data signal is processed as a pilot signal, and a portion corresponding to the other portion of the data signal is used as a data signal. Comprising a processing unit for processing, the.

  It should be noted that any combination of the above-described constituent elements, or those obtained by replacing the constituent elements and expressions of the present invention with each other between apparatuses, methods, systems, computer programs, recording media storing computer programs, and the like are also included in the present invention. It is effective as an embodiment of

  According to the present invention, it is possible to achieve both the reduction of the strength of a predetermined portion of the output time signal and the channel estimation using the pilot signal.

It is a schematic diagram which shows the structural example of the radio | wireless communications system which concerns on 1st Embodiment. It is a figure which shows the hardware structural example of the terminal of FIG. It is a block diagram which shows the function and structure of the communication apparatus of FIG. It is a block diagram which shows the function and structure which concern on transmission of the baseband signal processing part of FIG. FIG. 5 is a block diagram illustrating a function and a configuration relating to generation of an input data symbol sequence in an input sequence generation unit in FIG. 4. FIG. 6 is a data structure diagram illustrating an example of an input / output characteristic holding unit in FIG. 5. It is explanatory drawing of the data hold | maintained at the pilot codebook holding | maintenance part of FIG. FIG. 5 is a schematic diagram illustrating an example of a waveform of a signal generated by a pilot addition unit in FIG. 4. It is a block diagram which shows the function and structure which concern on reception of the base station apparatus of FIG. 2 is a chart showing a flow of a series of processes in the wireless communication system of FIG. FIGS. 11A and 11B are explanatory diagrams for explaining the ISI reduction effect between terminals. It is a block diagram which shows the function and structure of the baseband signal processing part which concern on a modification. It is a wave form diagram which shows an example of the data signal with LPT. It is a block diagram which shows the function and structure which concern on transmission of the baseband signal processing part which concerns on 2nd Embodiment. It is a data structure figure which shows an example of the code book holding | maintenance part of FIG. It is a time-domain waveform diagram which shows one example of the data signal which a receiver receives. It is a spectrum of the frequency domain which shows four examples of the data signal which a receiver receives.

  Hereinafter, the same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated description is appropriately omitted. In addition, in the drawings, some of the members that are not important for explanation are omitted.

(First embodiment)
In the first embodiment, a time-domain pilot signal is added to a low-intensity tail (Low Power Tail, hereinafter referred to as LPT) of a waveform obtained by DFTS-OFDM for a data symbol. This makes it possible to perform channel estimation without using frequency-domain pilot symbols or pilot subcarriers.

  With respect to the LPT, in the present embodiment, the OH symbol is set so that the influence of the data symbol included in the input symbol sequence on the tail and the influence of the overhead (OH) symbol included in the input symbol sequence on the tail cancel each other. decide. As a result, the value of the OH symbol is not a fixed value such as “0” but a value (for example, a complex number) that varies depending on the data symbol. Thereby, the strength of the tail can be reduced regardless of the data symbol, and the ISI and inter-subcarrier interference can be suppressed sufficiently low.

  FIG. 1 is a schematic diagram showing a configuration example of a radio communication system 100 according to the present embodiment. The radio communication system 100 includes a base station apparatus 101 and a terminal 102 that each operate as a radio communication apparatus. Although a system including one base station apparatus 101 and one terminal 102 is illustrated as an example, there may be a plurality of these communication apparatuses. The wireless communication system 100 is a cellular communication system that employs, for example, Long Term Evolution (LTE), but may be a subsequent generation cellular communication system or a wireless communication system such as a wireless LAN. That is, the following technique can be applied when an OFDM-based communication method is used between two communication apparatuses, and the target is not necessarily limited to a specific system such as a cellular communication system.

  Hereinafter, the configuration of the transmission apparatus (terminal 102) and the configuration of the reception apparatus (base station apparatus 101) in uplink (uplink), that is, signal transmission from the terminal 102 to the base station apparatus 101 will be described. However, it will be apparent to those skilled in the art who have touched this specification that the technical idea according to the present embodiment can be applied to any communication apparatus that transmits and receives signals using an OFDM-based communication method.

  FIG. 2 is a diagram illustrating a hardware configuration example of the terminal 102. The terminal 102 includes a CPU 201, a ROM 202, a RAM 203, an external storage device 204, and a communication device 205. In the terminal 102, for example, a computer program for realizing each function of the terminal 102 recorded in any of the ROM 202, the RAM 203, and the external storage device 204 is executed by the CPU 201. And the terminal 102 controls the communication apparatus 205, for example by CPU201, and performs communication between the base station apparatus 101 and the terminal 102. FIG.

  In FIG. 2, the terminal 102 has one communication device 205. However, for example, the terminal 102 may have a plurality of communication devices corresponding to a plurality of frequency bands. Note that the terminal 102 may have a communication device for receiving an uplink signal or a communication device for transmitting a downlink signal for direct communication between the terminals. May be. Further, the terminal 102 may include dedicated hardware for executing each function, or may be executed by a computer that executes a part of the hardware and executes a program. Alternatively, the terminal 102 may execute all the functions by a computer and a program.

  FIG. 3 is a block diagram showing the function and configuration of the communication apparatus 205 of FIG. The communication device 205 includes a baseband signal processing unit 302, a transmission / reception unit 304, an amplification unit 306, and an antenna 308.

  The transmission function of the communication device 205 will be described. The baseband signal processing unit 302 acquires transmission data that is user data to be transmitted. The baseband signal processing unit 302 performs precoding processing, discrete Fourier transform (DFT) processing, IDFT processing, pilot signal addition processing, and the like on the acquired transmission data. The baseband signal processing unit 302 transfers the baseband signal obtained as a result of these processes to the transmission / reception unit 304. The transmission / reception unit 304 modulates a carrier wave with the baseband signal output from the baseband signal processing unit 302, and generates a radio frequency signal having a desired radio frequency band. The amplification unit 306 amplifies the radio frequency signal generated by the transmission / reception unit 304 and transmits the amplified signal through the antenna 308.

  The reception function of the communication device 205 will be described. The radio frequency signal received by the antenna 308 is amplified by the amplification unit 306, demodulated by the transmission / reception unit 304, and converted into a baseband signal. The baseband signal processing unit 302 performs DFT processing, error correction decoding, and the like on the baseband signal.

  FIG. 4 is a block diagram illustrating functions and configurations related to transmission of the baseband signal processing unit 302 of FIG. The baseband signal processing unit 302 includes a first terminal 402, an input sequence generation unit 404, an OH parameter determination unit 408, a DFT unit 412, a frequency domain processing unit 414, an IDFT unit 416, and a pilot addition unit 418. , P / S conversion section 428, data OH parameter holding section 422, pilot OH parameter holding section 424, frequency profile selection section 430, pilot symbol determination section 432, pilot codebook holding section 434, 2 terminals 420.

  Input sequence generation section 404 receives a transmission data symbol, which is a symbol representing transmission data, from first terminal 402. The input series generation unit 404 acquires the data OH parameter from the data OH parameter holding unit 422. Based on the acquired data OH parameter and the received transmission data symbol, the input sequence generation unit 404 determines an OH symbol including a prefix OH symbol and a suffix OH symbol. Input sequence generation section 404 generates an input data symbol sequence by adding the determined OH symbol to the received transmission data symbol.

  Input sequence generation section 404 receives pilot symbols for channel estimation from pilot symbol determination section 432. Input sequence generation section 404 acquires pilot OH parameters from pilot OH parameter holding section 424. Based on the acquired pilot OH parameter and the received pilot symbol, input sequence generation section 404 determines an OH symbol including a prefix OH symbol and a suffix OH symbol. Input sequence generation section 404 generates an input pilot symbol sequence by adding the determined OH symbol to the received pilot symbol.

  The DFT unit 412, the frequency domain processing unit 414, and the IDFT unit 416 constitute a signal conversion unit 406. The signal conversion unit 406 converts the input data symbol sequence generated by the input sequence generation unit 404 into frequency domain frequency data. The signal converter 406 converts the frequency data obtained by the conversion into a time domain data signal having a desired frequency band, and outputs the data signal to the pilot adder 418. The signal conversion unit 406 converts the input pilot symbol sequence generated by the input sequence generation unit 404 into frequency domain frequency data. The signal conversion unit 406 converts the frequency data obtained by the conversion into a time domain pilot signal having a desired frequency band, and outputs the pilot signal to the pilot addition unit 418.

  The input data symbol series is a time domain series, and in particular, a time series of M symbols (M is a natural number). The input data symbol sequence is expressed by a vector having symbols as elements. This vector is denoted as an input symbol vector S. In the input symbol vector S, M elements are arranged along the time axis. The same applies to the input pilot symbol sequence.

  The DFT unit 412 performs serial / parallel conversion on the input data symbol sequence generated by the input sequence generation unit 404, converts the time domain sequence into frequency domain frequency data by performing DFT processing, and outputs the frequency domain processing unit 414 to the frequency domain processing unit 414. Output. The size (in this case, M) of the DFT corresponds to the bandwidth of the radio frequency signal generated by the transmission / reception unit 304.

  The frequency domain processing unit 414 performs predetermined processing in the frequency domain on the frequency data obtained as a result of the conversion in the DFT unit 412. For example, the frequency domain processing unit 414 maps the frequency data after DFT processing to a desired frequency band or an assigned frequency band, and maps a non-signal (0 signal) to other frequency bands. Is output to the IDFT unit 416.

  IDFT section 416 performs IDFT processing on the sequence output from frequency domain processing section 414, generates a data signal, and outputs the data signal to pilot adding section 418. The size of the IDFT (in this case, a natural number F greater than M) corresponds to the total received signal bandwidth of the base station apparatus 101. In particular, F may be the number of subcarriers available in the base station apparatus 101.

  DFT section 412, frequency domain processing section 414, and IDFT section 416 perform similar processing on the input pilot symbol sequence, generate a pilot signal, and output the pilot signal to pilot adding section 418.

  FIG. 5 is a block diagram showing functions and configuration relating to generation of an input data symbol sequence in input sequence generation section 404 of FIG. The input series generation unit 404 includes a data symbol acquisition unit 502, an input / output characteristic holding unit 504, an OH symbol calculation unit 506, and a synthesis unit 508.

An input symbol vector S of size M output from the input sequence generation unit 404 is
^{_{S = (h Nh T, d}} M-Nh-Nt T, t Nt T) T
It is expressed. Here, h _Nh is a prefix OH vector having Nh (Nh is an integer of 0 or more) prefix OH symbols as elements, and t _Nt is Nt (Nt is a natural number) suffix OH symbols as elements. This is a postfix OH vector. d _M-Nh-Nt is a transmission data vector composed of M-Nh-Nt transmission data symbols. Nh and Nt satisfy M> Nh + Nt. As described above, in this embodiment, precoding for generating an input data symbol sequence is performed by adding a different symbol to a transmission data symbol.

  In the input symbol vector S, the transmission data symbols are arranged so as to be sandwiched between the prefix OH symbol and the suffix OH symbol. The post-OH symbol is included in the input symbol vector S as an element corresponding to a time later than the time of the transmission data symbol. The prefix OH symbol is included in the input symbol vector S as an element corresponding to the previous time compared to the time of the transmission data symbol.

In input sequence generation section 404, Nh prefix OH symbols and Nt prefix OH symbols are transmitted to the rear end portion of the data signal output from signal conversion section 406 corresponding to input symbol vector S, that is, LPT. The influence of the data vector d _M-Nh-Nt and the influence of the front OH vector h _Nh and the rear OH vector t _{Nt on the} LPT are determined so as to cancel each other.

A vector whose elements are K time samples of the data signal output from the signal conversion unit 406 corresponding to the input symbol vector S is denoted as an output vector X. Elements corresponding to the tail of the elements of the output vector X, ie P counted from behind (P is smaller than K a natural number) is denoted a vector of elements from th element to the last element and the output tail vector X _P. The output tail vector _XP is a part of the output vector X. More specifically,
X = (x ₁ , x ₂ ,..., X _K−1 , x _K ) ^T
When written as
X _P = (x _{K−P + 1} , x _{K−P + 2} ,..., X _K ) ^T
It is. Output tail vector _{X P} corresponds to the LPT, the number P of elements of the output tail vector _{X P} is the length of the LPT.

Since the signal conversion unit 406 is a linear system, each element of the output tail vector X _P is expressed as a linear combination of elements of the input symbol vector S. That is,
_{X P = A · d M-} Nh-Nt + B · (h Nh T, t Nt T) T ... ( Equation 1)
Is established. Here, “·” represents a matrix product. A transmission data vector _{d M-Nh} to transmit data vector _{d M-Nh-Nt} and an input matrix representing the input-output characteristics of the signal conversion unit 406 to output the output tail vector _{X P,} i.e. the signal conversion unit 406 it is a matrix input _-Nt defines what effect the output tail vector X _P. B is pre OH before matrix representing the input-output characteristic of the location OH vector _{h Nh} and post OH vector _{t Nt} of the input output tail signal converter 406 to output a vector _{X P,} i.e. to the signal conversion unit 406 is a matrix input vectors h _Nh and post OH vector t _Nt defines what effect the output tail vector X _P. In order to minimize or minimize the signal strength in the LPT of the output vector X,
X _P = 0
Imposing. This is equivalent to the condition in which the first term and the second term on the right side of Equation 1 cancel each other. Then
(H _Nh ^T , t _Nt ^T ) ^T = (B ^H · B) ⁻¹ · B ^H · (−A) · d _M−Nh−Nt (Formula 2)
Is obtained. Here, B ^H represents an adjoint matrix of B.

Equation 2 is based on the transmission data vector d _M-Nh-Nt representing the transmission data symbol and the matrices A and B representing the input / output characteristics of the signal conversion unit 406, and the prefix OH vector h _Nh and the suffix OH vector It shows that t _Nt can be determined. The input sequence generation unit 404 obtains A and B corresponding to the set of P, Nh, and Nt in advance, and after obtaining the transmission data vector d _M-Nh-Nt , acts on the prefix OH vector by applying A and B thereto. h _Nh and postfix OH vector t _Nt are obtained and an input symbol vector S is constructed.

The data symbol acquisition unit 502 receives a transmission data symbol from the first terminal 402. The data symbol acquisition unit 502 refers to the data OH parameter holding unit 422 and identifies Nh and Nt to be used. Nh and Nt are both OH parameters for data. Data symbol acquisition section 502 collects M-Nh-Nt received transmission data symbols and generates transmission data vector d _M-Nh-Nt . The data symbol acquisition unit 502 outputs the generated transmission data vector d _M-Nh-Nt to the synthesis unit 508 and the OH symbol calculation unit 506.

Based on the transmission data vector d _M-Nh-Nt output from the data symbol acquisition unit 502 and the matrices A and B corresponding to the set of (P, Nh, Nt), the OH symbol calculation unit 506 A post OH vector h _Nh and a post OH vector t _Nt are determined. The OH symbol calculation unit 506 receives the transmission data vector d _M-Nh-Nt from the data symbol acquisition unit 502. The OH symbol calculation unit 506 refers to the data OH parameter holding unit 422 and identifies a set of (P, Nh, Nt) to be used.

  The OH symbol calculation unit 506 refers to the input / output characteristic holding unit 504 and acquires the matrices A and B corresponding to the specified (P, Nh, Nt) set. FIG. 6 is a data structure diagram showing an example of the input / output characteristic holding unit 504. The matrices A and B all depend on P, Nh, and Nt. In particular, the matrix A is a matrix of P rows (M−Nh−Nt) columns, and the matrix B is a matrix of P rows (Nh + Nt) columns. The input / output characteristic holding unit 504 holds a set of (P, Nh, Nt), a matrix A, and a matrix B in association with each other. Data registered in the input / output characteristic holding unit 504 may be registered at the time of shipment based on a test or simulation result before shipment to the signal conversion unit 406. The matrix A and the matrix B themselves are matrices whose elements are values unique to the device regardless of the state of the radio channel. Note that the matrices A and B may be directly obtained by calculation instead of being held in the holding unit.

Returning to FIG. 5, the OH symbol calculation unit 506 calculates the prefix OH vector h _Nh by calculating Equation 2 using the acquired matrices A and B and the received transmission data vector d _M-Nh-Nt. And determine the postfix OH vector t _Nt . The OH symbol calculation unit 506 outputs the determined prefix OH vector h _Nh and postfix OH vector t _Nt to the synthesis unit 508.

Combining unit 508 receives an input from transmission data vector d _M-Nh-Nt received from data symbol acquisition unit 502, and pre-OH vector h _Nh and post-OH vector t _Nt received from OH symbol operation unit 506. A symbol vector S is synthesized. The synthesizer 508 outputs the generated input symbol vector S to the signal converter 406.

  The processing for generating the input pilot symbol sequence by the input sequence generation unit 404 is performed by replacing the transmission data symbol with the pilot symbol and the data OH parameter holding unit 422 with the pilot OH parameter holding unit 424 in the above description. Explained. Further, since the number Np of pilot symbols is determined by a pilot symbol determining unit 432 described later, Nh and Nt of the pilot OH parameter holding unit 424 are determined so that M-Nh-Nt = Np is satisfied.

A vector having K time samples of the pilot signal output from the signal conversion unit 406 corresponding to the input pilot symbol sequence as an element is denoted as an output vector Y. Among the elements of the output vector Y, an element corresponding to the tail, that is, a vector composed of the elements from the Pth element (P ′ is a natural number smaller than K) from the back to the last element is referred to as an output tail vector YP _′ . write. The output tail vector YP _′ is a part of the output vector Y. Further, among the elements of the output vector Y, the element corresponding to the non-LPT part of the data signal, that is, the vector composed of the elements from the first element to the (KP) th element is denoted as the corresponding vector Y _KP . More specifically,
Y = (y ₁ , y ₂ ,..., Y _K−1 , y _K ) ^T
When written as
Y _{P ′} = (y _{K−P ′ + 1} , y _{K−P ′ + 2} ,..., Y _K ) ^T
_{Y K-P = (y 1} , ..., y K-P) T
It is. By imposing Y _{P ′} = 0 and Y _K−P = 0, an expression corresponding to Expression 2 is derived.

  Returning to FIG. 4, the OH parameter determination unit 408 determines the OH parameter to be used based on the size of the temporal overlap of symbols related to the radio frequency signal transmitted by the communication apparatus 205, and determines the determined OH The parameter is registered in the data OH parameter holding unit 422 and the pilot OH parameter holding unit 424. The data OH parameter includes P, Nh, and Nt. The OH parameter determination unit 408 determines the value of P based on the expected value and / or statistical value of the delay due to timing offset and multipath. The OH parameter determination unit 408 determines the values of Nh and Nt based on the determined value of P.

In one example, the OH parameter determination unit 408 may set an initial value of P based on the communicable range of the base station device. When the maximum radius of the communicable range is expressed as R _max and the speed of light is expressed as c, the maximum delay D _max within the communicable range is D _max = R _max / c
Given in. When the sampling interval is expressed as T _s , the initial value P _i of P is
P _i T _{s> D max}
Is given as the smallest integer that satisfies. That is, when [] is a Gaussian symbol,
P _i = [R _max / cT _s ] +1
Gives an initial value P _i .

The OH parameter determination unit 408 may perform statistical processing on the measured value of delay due to timing offset and multipath, and adjust the value of P based on the result of the processing. For example, when many delays exceeding the maximum delay D _max are observed, the OH parameter determination unit 408 may increase P from the initial value P _i . The actual measured value of the delay is obtained, for example, in a closed loop synchronization (CLS) process between the base station apparatus and the terminal. By repeating the closed-loop synchronization process, the actual measured delay value is accumulated.

The OH parameter determination unit 408 may determine Nh and Nt so that (Nh + Nt) increases as the determined P value increases and Nh <Nt. Nh <Nt is based on the inventor's finding that a strong influence of the higher positioned elements back to the output tail vector X _P in the input symbol vector S. Moreover, because of the periodicity of the IDFT processing in the signal conversion unit 406, which may also affect the output tail vector X _P positioned elements at the beginning of the input symbol vector S. Therefore, the value of Nh may be set to 1 or more. In one example, the OH parameter determination unit 408 has a table that holds P values and predetermined Nh and Nt pairs in association with each other, and includes Nh and Nt corresponding to the determined P values. Nh and Nt may be determined by specifying a set from the table. The data registered in the table may be obtained empirically or theoretically in advance.

  The pilot OH parameters include P ', Nh, and Nt. P ′ may be determined in the same manner as P. P '<P. For the determination of Nh and Nt, a constraint condition of M−Nh−Nt = Np is added.

  Alternatively, the OH parameter determination unit 408 receives control signals such as BCCH (Broadcast Control Channel), PDCCH (Physical Downlink Control Channel), and control signals such as PUCCH (Physical Uplink Control Channel) from control channels and data. These OH parameters may be determined by extracting pilot OH parameters.

FIG. 7 is an explanatory diagram of data held in the pilot codebook holding unit 434. Pilot code book holding section 434 holds an ID for identifying a set of pilot symbols and the value of each pilot symbol included in the set in association with each other. FIG. 7 shows an example of three pilot symbol sets when Np = 3. Sequence 1 includes three pilot symbols having the same value of “1 + i”. The frequency component | W (f) | ² of the pilot signal corresponding to the sequence 1 has a relatively flat profile. Sequence 2 includes three pilot symbols in a sequence of “1 + i, 1-i, 1 + i”. The frequency component | W (f) | ² of the pilot signal corresponding to the sequence 2 has two peaks. Sequence 3 includes three pilot symbols in a sequence of “1 + i, 1-i, 1-i”. The frequency component | W (f) | ² of the pilot signal corresponding to the sequence 3 has a local profile and one peak.

  Returning to FIG. 4, the frequency profile selection unit 430 selects the frequency profile of the pilot signal to be used based on the frequency characteristics of the channel to be estimated in the channel estimation. For example, the frequency profile selection unit 430 selects a relatively flat profile as the frequency profile when it is desired to estimate the influence of frequency selective fading. The frequency profile selection unit 430 selects a local profile as a frequency profile when it is desired to estimate the influence of flat fading.

  Pilot symbol determination section 432 determines pilot symbols to be provided to input sequence generation section 404 based on the frequency characteristics of the channel to be estimated. Pilot symbol determination section 432 acquires the selection result in frequency profile selection section 430, and identifies a pilot symbol corresponding to the acquired selection result from pilot codebook holding section 434. Pilot symbol determination section 432 provides the identified pilot symbols to input sequence generation section 404.

  For example, when a relatively flat profile is selected by the frequency profile selection unit 430, the pilot symbol determination unit 432 refers to the pilot codebook holding unit 434 and identifies the sequence 1 corresponding to the flat profile. When a local profile is selected in frequency profile selection section 430, pilot symbol determination section 432 refers to pilot codebook holding section 434 and identifies sequence 3 corresponding to the local profile.

  Pilot adder 418 adds the data signal output from signal converter 406 and the pilot signal output from signal converter 406 in the same manner. As a result of this addition processing, the non-low strength portion of the pilot signal is added to the LPT of the data signal, and the non-LPT portion of the data signal is added to the low strength portion of the pilot signal. For example, the pilot adder 418 stores the data signal previously obtained from the signal converter 406 in a buffer (not shown) such as a register. When pilot adder 418 next acquires the pilot signal from signal converter 406, pilot adder 418 superimposes the previously acquired data signal and the next pilot signal.

  The P / S conversion unit 428 performs parallel-serial conversion on the signal generated by the pilot addition unit 418 and outputs the serialized signal to the second terminal 420. The second terminal 420 is connected to the transmission / reception unit 304.

  FIG. 8 is a schematic diagram illustrating an example of a waveform of a signal generated by the pilot adder 418. A solid line waveform indicated by reference numeral 802 is a waveform of a signal generated by the pilot adder 418. A broken line waveform indicated by reference numeral 804 is a waveform of a data signal. A dashed-dotted line waveform indicated by reference numeral 806 is a pilot signal waveform. A portion indicated by reference numeral 808 is a portion where the LPT of the data signal and the LPT of the pilot signal are overlapped. The LPT of the data signal is longer than the LPT of the pilot signal, and a main body portion having a relatively high strength of the pilot signal is superimposed on the LPT of the data signal. The pilot signal has a low power head (hereinafter referred to as LPH) 810 in addition to the LPT. The main part of the data signal is superimposed on the pilot signal LPH 810.

  A signal having a solid line waveform indicated by reference numeral 802 is transmitted from the antenna 308 to the base station apparatus 101 through P / S conversion, modulation, amplification, and the like. Base station apparatus 101 demodulates the received signal and inputs it to DFT section 836. At this time, first, a signal replaced with 0 or no signal indicating that no signal other than the second intensity peak is received is input to the DFT unit 836 as a pilot signal. The output is used for channel estimation. Next, a signal obtained by replacing other than the first intensity peak with 0 or no signal is input to the DFT unit 836 as a data signal. The output is converted into received data.

  FIG. 9 is a block diagram showing functions and configurations related to reception of the base station apparatus 101 of FIG. Each block shown here can be realized by hardware and other elements such as a computer CPU and a mechanical device, and software can be realized by a computer program or the like. Draw functional blocks. Therefore, it is understood by those skilled in the art who have touched this specification that these functional blocks can be realized in various forms by a combination of hardware and software.

  Base station apparatus 101 includes demodulation section 830, S / P conversion section 832, separation section 834, DFT section 836, data OH parameter holding section 838, and pilot OH parameter holding section 840. The data OH parameter holding unit 838 and the pilot OH parameter holding unit 840 correspond to the data OH parameter holding unit 422 and the pilot OH parameter holding unit 424 of the baseband signal processing unit 302 shown in FIG. Holds content information.

  Demodulation section 830 acquires and demodulates the radio frequency signal transmitted from antenna 308 of terminal 102. The S / P converter 832 performs serial-parallel conversion on the signal obtained as a result of demodulation by the demodulator 830 and outputs the parallelized signal to the separator 834. The signal output from S / P converter 832 corresponds to the signal generated by pilot adder 418 of terminal 102.

  The processing unit of the base station apparatus 101 including the demultiplexing unit 834 and the DFT unit 836 is the portion corresponding to the LPT of the data signal among the signals obtained as a result of demodulation by the demodulation unit 830 (from (K−P + 1) th) The samples up to (KP ') are processed as pilot signals. The processing unit processes the first to (KP) th samples, which are portions corresponding to the main part of the data signal, as the data signal.

  The separation unit 834 stores the signal output from the S / P conversion unit 832 in a buffer (not shown). The separation unit 834 refers to the data OH parameter holding unit 838 and the pilot OH parameter holding unit 840, and acquires the values of P and P ′. First, the separation unit 834 extracts the (K−P + 1) th to (K−P ′) th samples from the stored signals as pilot signals. Specifically, the separation unit 834 reduces the intensities of the first to (K−P) th samples and the (K−P ′ + 1) th to Kth samples of the signal replicated from the buffer. Especially replace with zero. Separation section 834 outputs the extracted pilot signal to DFT section 836.

  Next, the separation unit 834 extracts the first to (KP) -th samples of the stored signals as data signals. Specifically, the separation unit 834 reduces the intensity of the (K−P + 1) th to Kth samples of the signal duplicated from the buffer, and replaces it with zero in particular. The separation unit 834 outputs the extracted data signal to the DFT unit 836. Since the processing after the DFT unit 836 is the same as the known signal processing, the description thereof is omitted.

The operation of the wireless communication system 100 configured as above will be described.
FIG. 10 is a chart showing a flow of a series of processes in the radio communication system 100. The base station apparatus 101 determines P ′, P, Nh, and Nt to be used (S702). The base station apparatus 101 notifies the determined P ′, P, Nh, and Nt to the terminal 102 through downlink control channels such as BCCH and PDCCH and control messages (S704). In the terminal 102, transmission data to be transmitted is generated by user operation, physical quantity measurement, or the like (S706). The terminal 102 determines an OH symbol included in the input data symbol sequence based on the transmission data, and determines an OH symbol included in the input pilot symbol sequence based on the pilot symbol (S708). The terminal 102 combines the input data symbol sequence by adding the determined OH symbol to the transmission data symbol, and combines the input pilot symbol sequence by adding the determined OH symbol to the pilot symbol (S710). The terminal 102 performs signal generation processing using the combined input data symbol sequence and input pilot symbol sequence as inputs (S712). In the baseband processing of the signal generation processing, terminal 102 adds the data signal corresponding to the input data symbol sequence and the pilot signal corresponding to the input pilot symbol sequence.

  The base station apparatus 101 receives the generated radio frequency signal from the terminal 102 (S714). When the terminal 102 measures the delay and uses new Nh and Nt values based on the measured delay, the terminal 102 transmits the new Nh and Nt to the base station apparatus via the uplink control channel. 101 is notified (S716). In this case, Nh and Nt notified in step S704 are different from Nh and Nt notified in step S716. The base station apparatus 101 performs signal reception processing for converting the received radio frequency signal into a baseband signal (S718). At this time, the base station apparatus 101 first extracts a pilot signal from the demodulated signal and uses it for channel estimation, and then extracts and processes a data signal. The base station apparatus 101 extracts transmission data from the received data series using the values of Nh and Nt (S720).

  FIG. 10 illustrates a case where the processing according to the present embodiment is applied to data transmission in the uplink. When the processing according to the present embodiment is applied to data transmission in the downlink, the processing flow is the same as in FIG.

  Note that the delay due to multipath may be measured, and it may be determined whether to perform precoding based on the measured delay. In this case, in FIG. 10, before step S702, (1) the base station apparatus 101 measures the multipath delay in the uplink, and (2) the base station apparatus 101 pre-links in the uplink based on the measured multipath delay. Decide whether to do coding. Regarding the downlink, first, (1) an instruction to measure the downlink multipath delay is transmitted from the base station apparatus 101 to the terminal 102, and (2) the multipath delay measured in response to the instruction is transmitted from the terminal 102. Based on the received multipath delay measurement value transmitted to the base station apparatus 101, the base station apparatus 101 determines whether or not to perform precoding. Here, Nh and Nt in the uplink and Nh and Nt in the downlink may be different.

  According to radio communication system 100 according to the present embodiment, it is possible to transmit a pilot signal using LPT of a data signal. Thus, both data signals and pilot signals can be transmitted within the same radio resource (ie, the same multicarrier symbol and the same band). As a result, data transmission and channel estimation can be performed in parallel even when frequency-domain pilot symbols and pilot subcarriers cannot be used. Further, the degree of freedom of resource allocation of pilot symbols and data symbols is increased.

  For example, when pilot symbols and pilot subcarriers in the frequency domain cannot be used, channel estimation by pilot and data transmission may be performed using different radio resources. However, it is inefficient that radio resources are occupied for channel estimation. In contrast, the method according to the present embodiment is more efficient because data transmission and channel estimation can be realized with the same radio resource.

  In radio communication system 100 according to the present embodiment, the main part of the data signal is overlapped with the LPH of the pilot signal, and the main part of the pilot signal is overlapped with the LPT of the data signal. Therefore, interference between the data signal and the pilot signal is suppressed.

  Furthermore, according to radio communication system 100 according to the present embodiment, the signal strength of the tail of the output signal can be suppressed, so that ISI between terminals due to timing shift between terminals and ISI due to multipath delay can be reduced. As a result, it is possible to construct a more efficient communication system that applies a common frame configuration to both large and small cells.

  FIGS. 11A and 11B are explanatory diagrams for explaining the ISI reduction effect between terminals. FIG. 11A shows a radio communication system including a base station apparatus 101 and first and second user terminals UE1 and UE2 each having the same configuration as the terminal 102. The first user terminal UE1 uses open-loop synchronization (OLS) and therefore does not perform propagation delay compensation for transmission (uplink) to the base station apparatus 101. The second user terminal UE2 uses CLS and compensates for propagation delay using timing advance or the like.

FIG. 11B is a diagram illustrating an uplink signal reception status in the base station apparatus 101. The signal S _UE1 transmitted from the first user terminal UE1 arrives at the base station apparatus 101 with a delay due to propagation delay. This is expressed by a rectangular area indicated by “UE1” in FIG. 11B protruding from the receiver window RW. The signal S _UE2 (rectangular area indicated by “UE2”) transmitted from the second user terminal UE2 so as to reach the next receiver window fits in the next receiver window because of propagation delay compensation. As a result, the tail of the signal transmitted from the first user terminal UE1 and the head of the signal transmitted from the second user terminal UE2 overlap in a period IUD having a length corresponding to the propagation delay of the first user terminal UE1. However, since the tail strength of the signal S _UE1 transmitted from the first user terminal UE1 is small in the present embodiment, the ISI in the period IUD is small. In addition, since the important part of the signal S _UE1 transmitted from the first user terminal UE1 has a relatively high intensity enters the receiver window RW and the intensity of the tail part outside the receiver window RW is small, the base station The device 101 can decode the signal S _UE1 transmitted from the first user terminal UE1 more accurately.

  In the case of ISI due to multipath delay, in the base station apparatus 101, ISI occurs because the rear end portion of the signal from the terminal 102 overlaps the front end portion of the next signal due to the multipath effect. In radio communication system 100 according to the present embodiment, the intensity of the tail of the signal is suppressed, and such ISI is reduced.

  Precoding according to the present embodiment can be applied to a terminal using OLS. In machine-type communications (IOT) such as Internet Of Things, synchronization processing before data transmission is omitted in order to reduce the cost of the communication device on the machine side and reduce the power consumption to extend the battery life. Many OLSs are used. In such a case, when the precoding according to the present embodiment is applied, the communication quality can be maintained satisfactorily.

  In radio communication system 100 according to the present embodiment, the OH symbol is determined so as to cancel the influence of the transmission data symbol on the tail of the output signal of signal conversion section 406 by the influence of the OH symbol on the tail. The Accordingly, for example, the intensity of the tail can be further reduced as compared with a case where a simple numerical value “0” is used instead of the OH symbol.

  In communication applications that require high reliability such as medical, safety, and emergency, the precoding according to the present embodiment is performed even when a terminal requests data reception from a base station other than its own serving base station. Applicable. In this case, the terminal is synchronized with the serving base station by CLS, but is not synchronized with other base stations. By applying the precoding according to the present embodiment to communication between such other base stations and terminals, it is possible to reduce ISI and realize better communication quality.

  The configuration and operation of the wireless communication system according to the first embodiment have been described above. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to each component and combination of processes, and such modifications are within the scope of the present invention.

  In the first embodiment, the case where the pilot signal is added to the LPT of the data signal has been described, but the present invention is not limited to this. The data signal may be generated such that the strength of a predetermined portion of the data signal is smaller than the strength of other portions. The predetermined portion may be a tip portion (LPH) or a central portion. The main part of the pilot signal may be added to a predetermined part where the strength of the data signal is low.

  In the first embodiment, in order to obtain the LPT, the OH symbol is determined so that the influence of the transmission data symbol on the tail of the output signal of the signal conversion unit 406 is offset by the influence of the OH symbol on the tail. However, the present invention is not limited to this. For example, the zero-tail DFTS-OFDM technique described in Non-Patent Document 1 may be used to obtain LPT.

  In the first embodiment, the case where the base station apparatus 101 determines P ′, P, and the like and notifies the terminal 102 of the determined P ′, P, and the like has been described with reference to FIG. Without being limited thereto, the terminal may determine P ′, P, etc., and notify the determined P ′, P, etc. to the base station apparatus. For example, if the terminal is a terminal adopting OLS, the terminal can transmit the first symbol to be transmitted to the base station apparatus including P ′, P, etc. Alternatively, the terminal 102 may include a notification unit that notifies the base station apparatus 101 of information held in its own data OH parameter holding unit 422 and pilot OH parameter holding unit 424. The base station apparatus 101 may update the contents of its own data OH parameter holding unit 838 and pilot OH parameter holding unit 840 with the notified information.

  In the first embodiment, the case where the OH symbols are arranged before and after the transmission data symbols in the input symbol vector S has been described, but the present invention is not limited to this. More generally, the number, position and value of OH symbols may be determined as follows.

Regarding the matrix V of K rows and M columns representing the input / output characteristics of the signal conversion unit 406,
X = V · S
Is established. X is an output vector. T, N _OH (= Nh + Nt) is a set (1, 2,..., M) of indexes of elements of the input symbol vector S (identifiers for identifying elements in the input symbol vector S, i's “i”) ) A set of indexes of OH symbols is denoted as J, and the other, that is, a set of indexes of M−N _OH transmission data symbols is denoted as D. J and D are each a subset of T, and D is a complementary set of J when T is a whole set.

ここでｐ（ｎ）はＩＳＩエネルギの分布を表し、経験的にまたは実測値の統計処理により得られる。特にｐ（ｎ）はタイミングオフセットおよびマルチパス遅延の確率分布により決定される。概略的には、ｐ（ｎ）が大きい場合、それは出力テールベクトルＸ_Ｐにおけるｎ番目の要素が統計的に大きくなる傾向にあることを示す。Ｖ（Ｋ−ｎ＋１：Ｋ、ｍ）は、Ｖの第ｍ列のなかの第（Ｋ−ｎ＋１）行目から第Ｋ行目までの要素からなるベクトルを表す。なお、同様にＸ_Ｐ＝Ｘ（Ｋ−Ｐ＋１：Ｋ）と表される。 when m is original T, then defined as follows contribution w _m to the output tail vector X _P from m-th element of the input symbol vector S.

Here, p (n) represents the distribution of ISI energy, and is obtained empirically or by statistical processing of actually measured values. In particular, p (n) is determined by the probability distribution of timing offset and multipath delay. Schematically, if p (n) is large, it indicates that there is a tendency that n-th element in the output tail vector X _P is greater statistically. V (K−n + 1: K, m) represents a vector composed of elements from the (K−n + 1) th row to the Kth row in the mth column of V. Similarly, X _P = X (K−P + 1: K).

w ₁ , w ₂ ,..., w _M are calculated, and N _OH pieces are selected in descending order from among them, and the set of indexes of the selected one is J. By this, the selected set of output tail vector X high impact N _OH number of indices to the _P from among the input symbol vector S (= position of the element) as J.

ＯＨシンボルからなるベクトルＳ（Ｊ）と送信データシンボルからなるベクトルＳ（Ｄ）とについて、Ｘ_Ｐ＝０を課すので、

これをＳ（Ｊ）について解くと、

となる。 Define the following matrices for D and J:

Since X _P = 0 is imposed on the vector S (J) composed of OH symbols and the vector S (D) composed of transmission data symbols,

Solving this for S (J)

It becomes.

  In the first embodiment, the case where both the input data symbol sequence and the input pilot symbol sequence are processed by the same signal conversion unit 406 has been described, but the present invention is not limited to this. For example, the baseband signal processing unit of the terminal may include a first signal conversion unit 472 for processing an input data symbol sequence and a second signal conversion unit 474 for processing an input pilot symbol sequence. Good. FIG. 12 is a block diagram illustrating functions and configurations of a baseband signal processing unit according to a modification. Each of the first signal converter 472 and the second signal converter 474 is configured in the same manner as the signal converter 406. The first signal converter 472 processes the input data symbol sequence to generate a data signal 478. Second signal converter 474 processes the input pilot symbol sequence to generate pilot signal 480. The pilot addition unit 476 adds the data signal 478 generated by the first signal conversion unit 472 and the pilot signal 480 generated by the second signal conversion unit 474 to generate a transmission signal 482.

  Alternatively, the pilot signal may be selected or acquired from a pilot holding unit that holds a predetermined pilot signal instead of being generated from the input pilot symbol sequence. In this case, the process of generating a pilot signal from the input pilot symbol sequence can be omitted.

  In the first embodiment, the case where baseband signal processing section 302 of terminal 102 has pilot codebook holding section 434 has been described, but this pilot codebook holding section 434 may be shared with base station apparatus 101. .

(Second Embodiment)
In the first embodiment, a case has been described in which a part of a signal is replaced with zero on the receiving side. In the second embodiment, a part of the LPT of the data signal is replaced with zero on the transmission side. As a result, out-of-band radiation when a delay occurs can be suppressed.

FIG. 13 is a waveform diagram showing an example of a data signal accompanied by LPT. The vertical axis represents the average signal intensity, and the horizontal axis represents the sample index. The length of _LPT is expressed as L _LPT (unit: number of samples). The length of the data signal is represented as J (unit: number of samples). The assumed maximum value of delay is expressed as D _max (unit: number of samples). The D _max may be the same as the D _max of the first embodiment, may be different. LPT is set to be longer than the assumed maximum delay (L _LPT > D _max ). As described in the first embodiment, this makes it possible to suppress ISI when a delay occurs and to improve the decoding accuracy of the signal.

In the present embodiment, the index n _{min of the} sample 604 that gives the local minimum closest to the sample 602 among the local minimum values that appear before the sample 602 having the index corresponding to (J−D _max ) is specified. To do. Then, the intensities of all the samples 606 where the index n satisfies n> n _min are replaced with zero. As a result, the LPT has (J−n _min ) zero intensity samples, and the spectrum of the data signal thus processed is invariant to a delay of (J−n _min ) or less and out of band. Radiation is suppressed.

If the maximum value _{D max} of the delayed envisaged is given, the number or value and position of the length _{L LPT} i.e. OH symbols LPT _is, L LPT - the _{(J-n min)} to minimize the _{L LPT} It can be optimized by choosing.

  The position of the minimum value of the average intensity of the data signal as shown in FIG. 13 (that is, the index of the sample having the minimum value) depends only on the configuration of the transmission apparatus and the statistical distribution of the input symbol vector S. Thus, the terminal can calculate its location offline and store it in memory.

Moreover, since the index of the minimum value in the LPT is determined when the parameters for generating the LPT are determined, it is possible to create a correspondence table for them. Given the maximum delay value D _max that is assumed, parameters for _min and LPT generation can be determined from the correspondence table. By performing this operation for all values that can be taken by the maximum value D _{max, it} is possible to generate a codebook that holds the maximum values D _max , n _min, and LPT generation parameters in association with each other.

  The configuration of a radio communication system including a terminal that is a transmission apparatus according to the present embodiment conforms to the configuration of radio communication system 100 according to the first embodiment described with reference to FIG. The hardware configuration of the terminal according to the present embodiment conforms to the hardware configuration of the terminal 102 according to the first embodiment described with reference to FIG. The function and configuration of the communication device of the terminal according to the present embodiment conforms to the function and configuration of the communication device 205 according to the first embodiment described with reference to FIG.

  FIG. 14 is a block diagram illustrating functions and configurations related to transmission of the baseband signal processing unit 620 according to the second embodiment. The baseband signal processing unit 620 includes a first terminal 402, an input sequence generation unit 404, a DFT unit 412, a frequency domain processing unit 414, an IDFT unit 416, a window processing unit 616, a replacement unit 618, and a P / S converter 428, second terminal 420, OH parameter holding unit 610, codebook holding unit 612, and parameter determining unit 614.

FIG. 15 is a data structure diagram illustrating an example of the code book holding unit 612. The code book holding unit 612 holds the maximum delay value D _max assumed, the sample index n _min giving the minimum value, and the LPT length L _LPT in association with each other.

Returning to FIG. 14, the parameter determination unit 614 refers to the codebook holding unit 612, and calculates the sample index n _min and the LPT length L _LPT that give the minimum value corresponding to the maximum delay value D _max that is assumed. decide. The parameter determination unit 614 determines the values of Nh and Nt based on the determined LPT length L _LPT . The parameter determination unit 614 registers the determined L _LPT , Nh, and Nt in the OH parameter holding unit 610. The input sequence generation unit 404 acquires L _LPT , Nh, and Nt from the OH parameter holding unit 610 and generates an input symbol vector S.

  The IDFT unit 416 generates a data signal corresponding to the input symbol vector S and outputs it to the window processing unit 616. The window processing unit 616 acquires the output data signal and attenuates both the front end portion and the rear end portion of the acquired data signal. As a result, as shown in FIG. 13, the average intensity of the first sample of the data signal is substantially zero, and the average intensity of the last sample is also substantially zero.

The replacement unit 618 acquires a data signal obtained as a result of the window processing by the window processing unit 616. The replacement unit 618 acquires the index n _min of the sample that gives the minimum value determined by the parameter determination unit 614. The replacement unit 618 replaces the intensities of all samples in which the index n satisfies n> n _min among the samples of the acquired data signal with zero or no signal indicating that transmission is not performed. The replacement unit 618 outputs the data signal after the replacement process to the P / S conversion unit 428.

  FIG. 16 is a time domain waveform diagram showing four examples of data signals received by the receiving apparatus. FIG. 17 shows frequency domain spectra showing four examples of data signals received by the receiving apparatus. The waveform and spectrum indicated by the broken line are those when no replacement processing is performed and no delay occurs. The waveform and spectrum indicated by the solid line are those when a replacement process is performed and no delay occurs. The waveform and spectrum indicated by the alternate long and short dash line are those when no replacement processing is performed and a delay occurs. The waveform and spectrum indicated by the two-dot chain line are those when a replacement process is performed and a delay occurs.

  If a delay occurs without performing the replacement process, the intensity of the last sample of the received data signal is not zero as indicated by reference numeral 630 in FIG. As a result, discontinuity occurs between the last sample (rightmost) and the first sample (leftmost) of the IDFT window on the receiving side, so that a relatively large out-of-band radiation is generated (the one-dot chain line in FIG. 17). This is due to the fact that IDFT has a circulating property and that steep fluctuations in the time axis have a wide range of frequency components.

  On the other hand, when a delay occurs in a state where the replacement process is performed, the intensity of the last sample of the received data signal is zero (two-dot chain line in FIG. 16). Therefore, the discontinuity between the last and first samples of the receiving IDFT window can be reduced or eliminated, and as a result, out-of-band radiation can be reduced or eliminated (two-dot chain line in FIG. 17).

  Further, by performing the replacement processing with zero or no signal, it is possible to reduce the PAPR (Peak to Average Power Ratio) and to save the power of the amplifier.

  The configuration and operation of the wireless communication system according to the second embodiment have been described above. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to each component and combination of processes, and such modifications are within the scope of the present invention.

In the second embodiment, a case has been described in which the local minimum value in LPT is regarded as zero, and the intensity of the sample after n _min is replaced with zero or no signal, but the present invention is not limited to this. The local minimum may not be zero. In this case, the value to be replaced may be a minimum value instead of zero. Alternatively, instead of n _min , another minimum value before or after the minimum value may be adopted, and the intensity of the sample after the adopted minimum value may be replaced with zero. Even in this case, out-of-band radiation can be reduced for a delay shorter than the portion replaced with zero.

In the second embodiment, the case has been described in which the _LPT length L _LPT is determined based on the assumed maximum delay value D _max . However, the present invention is not limited to this, and the LPT length L _LPT is the maximum value D _max. And may be determined independently.

  In the second embodiment, the case of applying window processing has been described. However, the present invention is not limited to this, and for example, filtering processing may be applied.

  In the second embodiment, in order to obtain the LPT, the OH symbol is determined so that the influence of the transmission data symbol on the tail of the output signal of the signal converter 406 is offset by the influence of the OH symbol on the tail. However, the present invention is not limited to this. For example, the zero-tail DFTS-OFDM technique described in Non-Patent Document 1 may be used to obtain LPT.

In the second embodiment, the case where the codebook holding unit 612 holds n _min has been described. However, the present invention is not limited to this. For example, all or a plurality of minimum value indexes in the LPT may be held. In this case, the parameter determination unit can determine the index of the minimum value other than n _min depending on the situation.

  101 base station device, 102 terminal, 201 CPU, 202 ROM, 203 RAM, 204 external storage device, 205 communication device.

Claims (17)

A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder that adds a time domain pilot signal for channel estimation to a predetermined portion of the data signal ;
The input symbol sequence includes a first symbol and a second symbol representing transmission data,
Said first symbol is transmitted, characterized in Rukoto be determined as a predetermined portion to the second symbol Affects and the influence of the predetermined portion to the first symbol gives cancel the data signal device . A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder that adds a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
The converting unit converts a pilot symbol sequence into frequency domain frequency data, converts the frequency data obtained by the conversion into the time domain pilot signal having a desired frequency band,
The strength of the portion corresponding to the other portions of the data signal of the pilot signal, the other parts transmit device you being smaller than the intensity of the pilot signal. A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder for adding a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
The pilot symbol sequence is converted into frequency data in the frequency domain, it comprises a separate converter for converting the frequency data obtained by the conversion to the pilot signal in the time domain with a desired frequency band, and
The strength of the portion corresponding to the other portions of the data signal of the pilot signal, the other parts transmit device you being smaller than the intensity of the pilot signal.   The transmission apparatus according to claim 2 or 3, further comprising a determination unit that determines pilot symbols included in the pilot symbol sequence based on frequency characteristics of a channel to be estimated. Pilot symbols that can be determined by the determination unit are:
A first pilot symbol whose frequency component of the corresponding pilot signal has a localized profile;
The transmission apparatus according to claim 4, wherein the frequency component of the corresponding pilot signal includes a second pilot symbol having a flat profile. The pilot symbol sequence includes pilot symbols and overhead symbols,
When the portion of the pilot signal corresponding to the other portion of the data signal is referred to as a low strength portion, the overhead symbol is defined as the influence of the pilot symbol on the low strength portion of the pilot signal and the low strength portion. 6. The transmission apparatus according to claim 2, wherein the transmission apparatus is determined so as to cancel the influence of the overhead symbol. The input symbol sequence includes a first symbol and a second symbol representing transmission data,
The first symbol is determined so that an influence of the second symbol on a predetermined portion of the data signal and an influence of the first symbol on the predetermined portion cancel each other. The transmission device according to any one of 2 to 6.   Generates a time domain pilot signal to be added to the predetermined part of the time domain data signal generated from the input symbol sequence, the intensity of the predetermined part being smaller than the intensity of the other part Transmitting at least one of pilot symbol length, index, and sequence information used to transmit A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. Converting to a smaller time domain data signal,
The pilot signal in the time domain for the channel estimation, and adding a predetermined portion of said data signal, only including,
The input symbol sequence includes a first symbol and a second symbol representing transmission data,
The transmission method according to claim 1, wherein the first symbol is determined so that the influence of the second symbol on a predetermined portion of the data signal cancels out the influence of the first symbol on the predetermined portion. . A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. The ability to convert to a smaller time domain data signal,
A function of adding a time-domain pilot signal for channel estimation to a predetermined portion of the data signal ;
The input symbol sequence includes a first symbol and a second symbol representing transmission data,
The first symbol is a computer program characterized Rukoto be determined as a predetermined portion to the second symbol Affects and the influence of the predetermined portion to the first symbol gives cancel the data signal . A transmitting device;
A receiving device that communicates wirelessly with the transmitting device,
The transmitter is
A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder that adds a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
The input symbol sequence includes a first symbol and a second symbol representing transmission data,
The first symbol is determined so that the influence of the second symbol on a predetermined portion of the data signal and the influence of the first symbol on the predetermined portion cancel each other.
The receiving device is:
A demodulator that demodulates a radio frequency signal modulated by a signal output from the adder of the transmitter;
Processing of processing a portion corresponding to a predetermined portion of the data signal as a pilot signal and processing a portion corresponding to another portion of the data signal as a data signal among signals obtained as a result of demodulation by the demodulator And a system. A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. Converting to a smaller time domain data signal,
Adding a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
The converting includes converting a pilot symbol sequence into frequency domain frequency data, and converting the frequency data obtained by the conversion into the time domain pilot signal having a desired frequency band;
The transmission method according to claim 1, wherein a strength of a portion of the pilot signal corresponding to another portion of the data signal is smaller than a strength of the other portion of the pilot signal. A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. The ability to convert to a smaller time domain data signal,
A function of adding a time-domain pilot signal for channel estimation to a predetermined portion of the data signal;
The converting function includes a function of converting a pilot symbol sequence into frequency domain frequency data, and converting the frequency data obtained by the conversion into the pilot signal in a time domain having a desired frequency band,
A computer program characterized in that the strength of a portion of the pilot signal corresponding to the other portion of the data signal is smaller than the strength of the other portion of the pilot signal. A transmitting device;
A receiving device that communicates wirelessly with the transmitting device,
The transmitter is
A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder that adds a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
The converting unit converts a pilot symbol sequence into frequency domain frequency data, converts the frequency data obtained by the conversion into the time domain pilot signal having a desired frequency band,
The strength of the portion of the pilot signal corresponding to the other portion of the data signal is smaller than the strength of the other portion of the pilot signal,
The receiving device is:
A demodulator that demodulates a radio frequency signal modulated by a signal output from the adder of the transmitter;
Processing of processing a portion corresponding to a predetermined portion of the data signal as a pilot signal and processing a portion corresponding to another portion of the data signal as a data signal among signals obtained as a result of demodulation by the demodulator And a system. A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. Converting to a smaller time domain data signal,
Adding a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
Converting a pilot symbol sequence into frequency domain frequency data, and converting the frequency data obtained by the conversion into the time domain pilot signal having a desired frequency band,
The transmission method according to claim 1, wherein a strength of a portion of the pilot signal corresponding to another portion of the data signal is smaller than a strength of the other portion of the pilot signal. A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. The ability to convert to a smaller time domain data signal,
A function of adding a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
A function of converting a pilot symbol sequence into frequency domain frequency data, and converting the frequency data obtained by the conversion into the pilot signal in the time domain having a desired frequency band, is realized in the transmission device,
A computer program characterized in that the strength of a portion of the pilot signal corresponding to the other portion of the data signal is smaller than the strength of the other portion of the pilot signal. A transmitting device;
A receiving device that communicates wirelessly with the transmitting device,
The transmitter is
A time-domain input symbol sequence is converted into frequency-domain frequency data, and the frequency data obtained by the conversion is a time-domain data signal having a desired frequency band, and the intensity of a predetermined part is the intensity of another part. A conversion unit for converting to a data signal in a smaller time domain,
An adder for adding a time domain pilot signal for channel estimation to a predetermined portion of the data signal;
Another conversion unit that converts a pilot symbol sequence into frequency domain frequency data and converts the frequency data obtained by the conversion into the pilot signal in the time domain having a desired frequency band, and
The strength of the portion of the pilot signal corresponding to the other portion of the data signal is smaller than the strength of the other portion of the pilot signal,
The receiving device is:
A demodulator that demodulates a radio frequency signal modulated by a signal output from the adder of the transmitter;
Processing of processing a portion corresponding to a predetermined portion of the data signal as a pilot signal and processing a portion corresponding to another portion of the data signal as a data signal among signals obtained as a result of demodulation by the demodulator And a system.

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