WO2012105074A1

WO2012105074A1 - Receiving device, receiving method, receiving program and communication system

Info

Publication number: WO2012105074A1
Application number: PCT/JP2011/068186
Authority: WO
Inventors: 貴司吉本; 良太山田; 加藤　勝也
Original assignee: シャープ株式会社
Priority date: 2011-02-03
Filing date: 2011-08-09
Publication date: 2012-08-09
Also published as: JP2012165064A

Abstract

The present invention provides a receiving device, a receiving method, a receiving program or a communication system capable of determining a proper data signal segment even under an environment where a delay path with a delay time longer than a GI length is generated. A receiving unit (202) receives a signal, signal detecting units (221-1, 221-2) extract a signal having a segment with a predetermined length from the received signal, a decoding unit (211) decodes the signal of the extracted segment, a synchronizing unit (203) detects a plurality of timings from the received signal on the basis of mutually different criterion, and each of the signal detecting units (221-1, 221-2) defines a segment to extract a signal by using one of the detected plurality of timings.

Description

Reception device, reception method, reception program, and communication system

The present invention relates to a receiving device, a receiving method, a receiving program, and a communication system.
This application claims priority on February 3, 2011 based on Japanese Patent Application No. 2011-021939 filed in Japan, the contents of which are incorporated herein by reference.

In a wireless communication system such as a cellular phone and a wireless LAN, a plurality of paths (multipaths) are generated by reflecting or diffracting a transmitted radio wave by an obstacle such as a building or terrain. Interfering with each other causes inter-symbol interference (Inter Symbol Interference: ISI) or inter-carrier interference (Inter Carrier Interference; ICI). Therefore, in order to extract a signal without being affected by ISI or ICI, in a multicarrier transmission scheme, for example, orthogonal frequency division multiplexing (OFDM), a guard having a certain length (GI length). A signal in which an interval (GI; Guard Interval, for example, CP; Cyclic Prefix) is inserted before the data signal is transmitted.

For example, in Non-Patent Document 1, a correlation value between a pilot signal included in a received signal and a signal obtained by delaying an original pilot signal held by the receiving device is calculated, and the receiving device calculates the calculated correlation value. Describes the FFT synchronization that determines the end of the GI section included in the received signal, that is, the start position (FFT start position) of the data signal section (FFT section), based on the delay amount that gives the peak.
Further, in Non-Patent Document 2, in FFT synchronization, a delay amount in a predetermined section centered on a correlation value peak and a radio wave of a path (path) whose received power exceeds a predetermined threshold is received. It is described that the start position of the data signal interval is determined based on the amount, and thereby the data signal interval can be easily determined even when the reception power of the delay path is larger than the reception power of the preceding path.

However, the inventions described in

Non-Patent Documents

1 and 2 have a problem that, when the delay time for the delay path exceeds the GI length, the data signal section cannot be determined without missing a part of the data signal in the data signal section. There is a point.
The present invention has been made in view of the above points, and an object of the present invention is to provide a receiving apparatus, a receiving method, a receiving program, and a communication system that can determine an appropriate data signal section.

The present invention has been made in view of the above points, and an object thereof is to provide a receiving device, a receiving method, a receiving program, and a communication system.

(1) The present invention has been made to solve the above-described problems, and one aspect of the present invention includes a receiving unit that receives a signal, and a signal having a predetermined length from the received signal. A plurality of signal detection units to extract, a decoding unit to decode the signal of the extracted section, and a synchronization unit to detect a plurality of timings based on different criteria from the received signal, each of the signal detection units A receiving apparatus is characterized in that a section for extracting a signal is determined using one of the detected timings.

(2) According to another aspect of the present invention, the plurality of signal detection units include a first signal detection unit and a second detection unit, and the first signal detection unit converts the received signal into a time. A time-frequency conversion unit for converting from a domain to a frequency domain, wherein the second signal detection unit generates a residual signal obtained by removing an interference replica generated based on a signal decoded by the decoding unit from the received signal. An interference cancellation unit to generate, and a time-frequency conversion unit that converts the residual signal from the time domain to the frequency domain, wherein the first signal detection unit and the second signal detection unit use different timings, respectively. Determining a section in which a signal is extracted.

(3) According to another aspect of the present invention, the first signal detector performs processing on the received signal, and then the second signal detector satisfies a predetermined condition. The receiving apparatus is characterized in that it is repeatedly performed until it is received.

(4) According to another aspect of the present invention, the synchronization unit detects the timing based on a signal-to-interference noise ratio of the reception signal as one of the references. .

(5) According to another aspect of the present invention, the synchronization unit detects a timing at which the signal-to-interference / noise ratio becomes maximum.

(6) According to another aspect of the present invention, the synchronization unit detects the timing based on a signal-to-interference noise ratio of the received signal as one of the references, and the first signal detection unit A receiving apparatus is characterized in that a section for extracting a signal is determined based on the detected timing.

(7) According to another aspect of the present invention, the synchronization unit detects the timing based on a signal-to-noise ratio of the reception signal as one of the references.

(8) According to another aspect of the present invention, the synchronization unit detects a timing at which the signal-to-noise ratio is maximized.

(9) According to another aspect of the present invention, the synchronization unit detects the timing based on a signal-to-noise ratio of the received signal as one of the references, and the second signal detection unit includes: The receiving apparatus is characterized in that a section for extracting a signal is determined based on the detected timing. *

(10) According to another aspect of the present invention, the synchronization unit detects the timing based on power of the reception signal as one of the references.

(11) According to another aspect of the present invention, the synchronization unit detects a timing at which the power of the reception signal becomes maximum.

(12) According to another aspect of the present invention, the synchronization unit detects the timing based on power of the reception signal as one of the references, and the second signal detection unit detects the detection. The receiving apparatus is characterized in that a section for extracting a signal is determined based on the determined timing.

(13) According to another aspect of the present invention, the synchronization unit detects the timing based on an arrival path of the reception signal as one of the references.

(14) According to another aspect of the present invention, the synchronization unit detects a timing at which the arrival path first arrives.

(15) According to another aspect of the present invention, the synchronization unit detects the timing based on an arrival path of the received signal as one of the references, and the second signal detection unit detects the detection. The receiving apparatus is characterized in that a section for extracting a signal is determined based on the determined timing.

(16) According to another aspect of the present invention, the synchronization unit detects the timing based on an error frequency of the decoded signal as one of the references. .

(17) In another aspect of the present invention, the synchronization unit detects a timing at which the error frequency is minimized.

(18) According to another aspect of the present invention, the synchronization unit detects the timing based on an error frequency of the decoded signal as one of the references, and the second signal detection unit A receiving apparatus is characterized in that a section for extracting a signal is determined based on the detected timing.

(19) According to another aspect of the present invention, the synchronization unit detects the timing based on a signal-to-noise ratio of the received signal as one of the references, and the first signal detection unit includes: The receiving apparatus is characterized in that a section for extracting a signal is determined based on the detected timing.

(20) According to another aspect of the present invention, there is provided a receiving method in a receiving device, wherein the receiving device receives a signal first, and the receiving device is predetermined from the received signal. A plurality of second processes for extracting a signal of a length section, a third process in which the receiving apparatus decodes the signal of the extracted section, and a reference in which the receiving apparatus is different from the received signal. And a fourth process of detecting a plurality of timings, wherein each of the plurality of second processes defines a section for extracting a signal using one of the detected plurality of timings, Is a receiving method characterized by the above.

(21) According to another aspect of the present invention, there is provided a first procedure for receiving a signal to a computer included in a receiving apparatus, and a plurality of second procedures for extracting a signal having a predetermined length from the received signal. A receiving program for executing a fourth procedure for detecting a plurality of timings based on different criteria from the received signal, a third procedure for decoding the signal of the extracted section, Each of the second procedures is a receiving program characterized in that a section for extracting a signal is determined using one of the detected timings.

(22) According to another aspect of the present invention, there is provided a communication system including a transmission device that transmits a signal and a reception device that receives the signal, and the reception device has a predetermined length from the reception signal. A plurality of signal detectors for extracting signals in the interval, a decoder for decoding the signals in the extracted interval, and a synchronization unit for detecting a plurality of timings based on different criteria from the received signal, Each of the signal detection units is a communication system characterized by determining a section for extracting a signal using one of the detected timings.

According to the present invention, a received data signal can be demodulated without error under the influence of multipath.

1 is a conceptual diagram showing a communication system 1 according to a first embodiment of the present invention. 1 is a schematic diagram of a transmission device 100 according to the present embodiment. It is a conceptual diagram which shows an example of the frame format of the OFDM signal which concerns on this embodiment. It is a conceptual diagram which shows an example of the sub-frame format of the OFDM signal which concerns on this embodiment. It is a schematic block diagram which shows the structure of the receiver 200 which concerns on this embodiment. It is the schematic which shows the structure of the synchronizer 203 which concerns on this embodiment. It is a conceptual diagram showing an example of the signal energy and interference energy which concern on this embodiment. It is a conceptual diagram showing the other example of the signal energy and interference energy which concern on this embodiment. It is a conceptual diagram showing an example of the signal energy which concerns on this embodiment. It is a conceptual diagram showing the other example of the signal energy which concerns on this embodiment. It is the schematic which shows the structure of the interference removal part 205 which concerns on this embodiment. It is the schematic which shows the structure of the replica production | generation part 251 which concerns on this embodiment. It is a flowchart which shows the reception process which concerns on this embodiment. It is the schematic which shows the structure of the synchronizer 303 which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the structure of the synchronizer 403 which concerns on the 3rd Embodiment of this invention. It is the schematic which shows the structure of the synchronizer 503 which concerns on the 4th Embodiment of this invention. It is the schematic which shows the structure of the timing detection part 533-1 which concerns on the 4th Embodiment of this invention. It is the schematic which shows the structure of the transmitter 700 which concerns on the 5th Embodiment of this invention. It is the schematic which shows the structure of the receiver 600 which concerns on this embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing a communication system 1 according to the present embodiment. The communication system 1 includes a transmission device 100 and a reception device 200.
The transmission device 100 is, for example, a base station device, particularly a transmission part thereof, and transmits data to the reception device 200 by using, for example, an OFDM method via a downlink of a mobile phone system.
The receiving device 200 is, for example, a mobile station device, particularly a receiving part thereof, and receives data from the transmitting device 100.

As described above, in this embodiment, a case will be described as an example in which data is applied to a downlink in which data is transmitted from the base station apparatus as the transmission apparatus 100 to the mobile station apparatus as the reception apparatus 200 using the OFDM scheme. However, the present invention is not limited to a mobile phone system, and can be applied to other transmission systems that transmit data signals by adding a GI to other wireless communication systems such as a wireless LAN, or a mobile phone system. It can also be applied to the uplink.

Next, the transmission device 100 according to the present embodiment will be described.
FIG. 2 is a schematic diagram of the transmission device 100 according to the present embodiment. The transmission apparatus 100 includes an encoding unit 101, a modulation unit 102, a control signal generation unit 103, a reference signal generation unit 104, a resource mapping unit 105, an IDFT unit 106, a GI insertion unit 107, a transmission unit 108, and a transmission antenna 109. Is done.
The encoding unit 101 performs error correction encoding processing on a data signal input from an upper layer (not shown) and outputs encoded bits. Here, the upper layer is a layer of functions higher than the physical layer (physical layer) among the layers of communication functions defined in the OSI reference model, for example, a data link layer, a network layer, and the like.
The input data signal may include an error detection code, for example, an error detection code such as a CRC (Cyclic Redundancy Check) code. The error correction coding process is, for example, turbo coding, LDPC (Low Density Parity Check) or convolutional coding processing.
Also, the encoding unit 101 may include a rate matching processing unit for adjusting the coding rate (coding rate) to the data transmission rate. In the rate matching processing unit, for example, puncture processing for deleting some data, repetition for repeating some data, or padding for inserting temporary data (for example, zero value) to some data Processing such as (Padding) is performed.

The modulation unit 102 modulates the coded bits input from the coding unit 101 and generates data modulation symbols. The modulation process performed by the modulation unit 102 includes, for example, BPSK (Binary Phase Shift Keying; two-phase phase modulation), QPSK (Quadrature Phase Shift Keying; four-phase phase modulation), 16QAM (16 Quadrature Amplitude Modulation value). Or 64QAM (64 Quadrade Amplitude Modulation; 64-value quadrature amplitude modulation). Modulation section 102 outputs the generated data modulation symbol to resource mapping section 105. Modulation section 102 may interleave the generated data modulation symbols and output the interleaved data modulation symbols to resource mapping section 105.

The control signal generation unit 103 encodes control data input from an upper layer (not shown), modulates the encoded control data to generate a control signal, and sends the generated control signal to the resource mapping unit 105 Output.
The control signal is a control signal for notifying the receiving apparatus of, for example, a synchronization signal or a modulation and coding scheme (MCS) such as a coding rate and a modulation multi-level number for a data signal.
The synchronization signal is, for example, a primary synchronization signal (PSS; Primary Synchronization Signal) and a secondary synchronization signal (SSS; Secondary Synchronization Signal). The PSS is a data sequence that can detect the symbol timing and the cell ID, for example, an orthogonal sequence such as a Zadoff-Chu sequence. The cell ID is an ID assigned to each cell corresponding to the base station apparatus (transmitting apparatus 100), and the mobile station apparatus (receiving apparatus 200) identifies the cell, that is, the base station apparatus (transmitting apparatus 100). It becomes a clue. The SSS is a data series that can detect frame timing, for example, an M series.
In LTE (Long Term Evolution), which is one of the standards of mobile communication systems, 168 cell groups corresponding to SSS and three intra-group cells corresponding to PSS, a total of 504 (168 × 3) cell recognitions A number is defined.
The control signal for notifying the receiving apparatus of MCS is, for example, PDCCH (Physical Downlink Control Channel).

The reference signal generation unit 104 generates a reference signal (RS; Reference Signal) for estimating a transfer function in the receiving apparatus, and outputs the generated reference signal to the resource mapping unit 105. The code sequence constituting the reference signal is an orthogonal sequence, for example, a Hadamard code or a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence.
The resource mapping unit 105 assigns the data modulation symbol input from the modulation unit 102, the control signal input from the control signal generation unit 103, and the reference signal input from the reference signal generation unit 104 to resource elements. A resource element is a minimum unit for assigning a data modulation symbol, a control signal, and a reference signal, and is specified by one subcarrier corresponding to a predetermined frequency band and one OFDM symbol corresponding to a predetermined time interval. That is, the resource element is a frequency region defined for each predetermined time interval. Resource mapping section 105 outputs the frequency domain signal assigned to the resource element to IDFT section 106.

The IDFT unit 106 performs an inverse discrete Fourier transform (IDFT) on the frequency domain signal output from the resource mapping unit 105, converts the frequency domain signal into a time domain signal, and inserts the converted time domain signal into the GI. Output to the unit 107. The IDFT unit 106 performs a function of converting a frequency domain signal into a time domain signal, but is not limited thereto, and may execute, for example, an inverse fast Fourier transform (IFFT). .
GI insertion section 107 adds an GI to the time domain signal input from IDFT section 106 and generates an OFDM symbol. That is, the GI insertion unit 107 uses the time domain signal as an effective symbol and prepends a part of the latter half thereof as an effective symbol as GI. An effective symbol to which this GI is added is an OFDM symbol.
The GI insertion unit 107 outputs the generated OFDM symbol to the transmission unit 108. By using this OFDM symbol, receiving apparatus 200 can remove distortion due to a delay path having a delay time shorter than the GI length. For example, in LTE, the GI length, that is, the number of sample points is 144 (6.7 μs).
The signal s _l (t) of the l-th OFDM symbol output from the GI insertion unit 107 is expressed by the following equation.

However, lT _s ≦ t <(l + 1) T _s , T _s is the OFDM symbol length (T _s = T _f + T _G ), T _f is the FFT interval length, _TG is the GI length, N _f is the number of IDFT points, C _{k, l} is the l-th OFDM first k allocated data modulation symbols to the subcarriers of the symbol, the control signal or reference signal, the delta _f is the sub-carrier interval. For example, in LTE, N _f is 2048 and Δ _f is 15 kHz.
The transmission unit 108 performs D / A (Digital-to-Analog) conversion of the OFDM symbol input from the GI insertion unit 107 to generate an analog signal, and band-limits the generated analog signal by filtering processing. To generate a band-limited signal. Transmitter 108 upconverts the generated band-limited signal to a radio frequency band to generate a carrier band OFDM signal, and transmits the carrier band OFDM signal generated from antenna 109 to reception apparatus 200 as a radio wave. Note that the transmission apparatus 100 may include a plurality of antennas 109 and perform diversity (Diversity) transmission or MIMO (Multiple Input Multiple Output) transmission.

Next, the frame format of the OFDM signal transmitted by the transmission apparatus 100 will be described.
FIG. 3 is a conceptual diagram showing an example of the frame format of the OFDM signal according to the present embodiment. In FIG. 3, the horizontal direction indicates time. As shown in FIG. 3, each frame of the OFDM signal includes 10 subframes. Each subframe includes two slots. Each slot is configured to include 7 OFDM symbols.
The PSS is indicated in the sixth OFDM symbol of each of the 0th subframe and the 5th subframe (filled portion in FIG. 3). The SSS is indicated in the fifth OFDM symbol of each of the 0th subframe and the 5th subframe (shaded portion in FIG. 3). Note that the PSS and SSS channels are defined in advance in the communication system 1 and stored in a storage device (not shown) in the transmission device 100 and the reception device 200.

Next, a subframe format of a transmission signal transmitted by transmission apparatus 100 will be described.
FIG. 4 is a conceptual diagram showing an example of the subframe format of the OFDM signal according to the present embodiment. However, the example illustrated in FIG. 4 is an example in which the transmission apparatus 100 transmits an OFDM signal using one antenna.
In FIG. 4, the horizontal direction indicates time and the vertical direction indicates frequency. FIG. 4 shows formats of the 0th subframe and the 5th subframe in FIG. The PSS is the sixth OFDM symbol and is arranged in a resource element composed of 63 subcarriers (frequency bands) in the middle of the system band (filled portion). SSS is the fifth OFDM symbol and is arranged in a resource element composed of 63 subcarriers (frequency bands) in the middle of the system band (shaded portion). Data modulation symbols and reference signals are allocated in units of resource blocks (thick lines).
Each resource block is composed of 168 resource elements that occupy a frequency indicated by 12 subcarriers and a time indicated by 14 OFDM symbols. Of the 14 OFDM symbols constituting each resource block, control signals such as PDCCH (Physical Downlink Control Channel) are mainly arranged in the first three regions. The remaining 11 OFDM symbol regions are regions in which data modulation symbols are mainly arranged. The reference signal is arranged in a predetermined resource element that configures each resource block (upward diagonally shaded portion).

Next, the configuration of the receiving device 200 according to this embodiment will be described.
FIG. 5 is a schematic block diagram illustrating a configuration of the receiving device 200 according to the present embodiment.
The reception apparatus 200 includes an antenna unit 201, a reception unit 202, a synchronization unit 203, a propagation path estimation unit 204, a demapping unit 209, a demodulation unit 210, a decoding unit 211, a switching unit 212, and a signal detection unit 221-α (α is 1 or 2). The signal detection unit 221-1 includes a GI removal unit 206-1, a DFT unit 207-1, and a propagation path compensation unit 208-1.
The signal detection unit 221-2 includes an interference removal unit 205, a GI removal unit 206-2, a DFT unit 207-2, and a propagation path compensation unit 208-2. The reception unit 202 outputs an output signal to the signal detection unit 221-1 or 221-2. As will be described later, when an error is detected in the signal that has passed through the signal detection unit 221-1, the output signal from the reception unit 202 is not output to the signal detection unit 221-1, and the signal detection unit 221- Output to 2.

The antenna unit 201 receives the carrier band OFDM signal propagated as a radio wave from the transmission apparatus 100, and outputs the received carrier band OFDM signal to the reception unit 202.
The receiving unit 202 down-converts the OFDM signal input from the antenna unit 100 to a frequency band where digital signal processing is possible, and further performs filtering processing on the down-converted signal to remove unnecessary components (Spurious). The receiving unit 202 converts the filtered signal from an analog signal to a digital signal (A / D; Analog-to-Digital), and the converted digital signal is synchronized with a synchronization unit 203, a propagation path estimation unit 204, and a switching unit. The signal is output to the signal detection unit 221-1 or 221-2 via 212. Here, the reception unit 202 initially outputs the converted digital signal to the signal detection unit 221-1 without outputting it to the signal detection unit 221-2. In other words, the switching unit 212 outputs the digital signal input from the receiving unit 202 to the signal detecting unit 221-1 when the digital signal output from the receiving unit 202 is not decoded by the decoding unit 211 ( b). When the decoding unit 211 detects an error based on the signal output to the signal detection unit 221-1, the reception unit 202 outputs the converted digital signal to the signal detection unit 221-2. That is, when there is an error in the decoding unit 211 based on the digital signal output from the receiving unit 202, the switching unit 212 outputs the digital signal input from the receiving unit 202 to the signal detecting unit 221-2 (connected to a). ).
In addition, when the decoding unit 211 performs decoding processing on the digital signal output from the receiving unit 202 one or more times, the switching unit 212 transmits the digital signal input from the receiving unit 202 to the signal detecting unit 221-2. May be output (connected to a).
In addition, when the soft decision value for the digital signal output from the receiving unit 202 is not input from the decoding unit 211 to the interference removing unit 205 from the decoding unit 211, the switching unit 212 receives the digital signal input from the receiving unit 202 as the signal detecting unit 221. -1 (connected to b), and when the soft decision value for the digital signal output from the receiving unit 202 is input from the decoding unit 211 to the interference removing unit 205, the digital signal input from the receiving unit 202 is The signal may be output to the signal detector 221-2 (connected to a).

The synchronization unit 203 performs a synchronization process with the transmission apparatus 100 using a control signal (for example, PSS, SSS).
FIG. 6 is a schematic diagram illustrating a configuration of the synchronization unit 203 according to the present embodiment. The synchronization unit 203 includes a filter unit 231, a correlation unit 232, and a timing detection unit 233-β (β is 1 or 2).
The filter unit 231 extracts the band component signal of the subcarrier in which PSS or SSS is arranged from the digital signal input from the reception unit 202, and outputs the extracted band component signal of the subcarrier to the correlation unit 232. For example, in the example of the frame format of the OFDM signal shown in FIG. 4, the filter unit 231 extracts 63 subcarrier band components included in the system band. In order to extract this component, the filter unit 231 uses a time domain filter whose pass band is a band of 63 subcarriers, for example, FIR (Finite Impulse Response Filter), IIR (Infinite Impulse Response Filter), or a matched filter (Matched Filter). Filter) can be used.

Signal r _s of the filter unit 231 outputs is expressed by the following equation.

Here, the signal r _s is a column vector (r ₀ ... R _m ... R _{Ns + D− 2} ) ^T having (N _s + D−1) elements. The element of this column vector is the output value r _m (0 ≦ m <N _s + D) at the discrete time m. N _s is the total value of the number of DFT points N _f and the number of sample points N _{G of} GI. D is the number of multipaths.
The matrix h is a matrix of (N _s + D−1) rows N _s columns composed of complex amplitudes h _d (0 ≦ d <D) in the d-th path, and is expressed by the following equation.

Complex amplitude _{h d} shows a propagation path characteristic of the d path from the antenna unit 109 of the transmitting apparatus 100 to the antenna unit 201 of the receiving device 200. n is the amplitude _n consists noise _{_{m (N s + D-1}} ) noise vector having a number of elements _{_{_{(n 0 ... n m ... n}}} Ns + D-2) T.
The s _PSS is a column vector (s _{PSS, 0} ... s _{PSS, m)} having N _s elements composed of _{the mth} OFDM symbol s _{PSS, m} in which the synchronization signal (PSS) extracted by the filter unit 231 is arranged. ... s _{PSS, Ns-1} ) ^T. The OFDM symbol s _{PSS, m} is a sequence C _{k, m} (a signal arranged in a resource element filled and shaded in FIG. 4) arranged in the k-th subcarrier of the m-th OFDM symbol, for example, It is expressed as:

Correlation section 232 calculates the correlation between the PSS indicated by the subcarrier band component signal input from filter section 231 and the PSS previously stored in the storage area, and calculates the complex amplitude based on the calculated correlation. Here, the correlation unit 232 prepends the signal r _s input from the filter unit 231 with N _f value zeros, and the signal sequence r _c (= 0 0... [N _f pieces]... 0 r ₀ . r _m ... r _{Ns + D−1} ) is generated. To prepend N _f number of value zero to the signal r _s, in order to provide a delay of N _f samples the signal r _s. OFDM symbol _{s PSS,} with _m and signal sequence _{r c,} complex amplitude _{h u} at the sample points of the u can be expressed, for example, as follows.

The correlation unit 232 outputs the calculated complex amplitude to the timing detection units 233-1 and 233-2.
The timing detection unit 233-1 includes a SINR (Signal to Interference Noise Ratio) estimation unit 234 and a first timing determination unit 235. The SINR estimation unit 234 estimates SINR based on the complex amplitude input from the correlation unit 232 and outputs the estimated SINR to the first timing determination unit 235.
Here, SINR estimation unit 234, around the sample complex amplitude h _u input from the correlation unit 232 is maximized, to extract a predetermined number of samples of the interval as the arrival path. In the present embodiment, a sample in which the square of the absolute value of the complex amplitude h _u | h _u | ² is equal to or greater than a predetermined threshold value α may be extracted as an arrival path.
The SINR estimation unit 234 uses the extracted sample point x _d (d is the sample point of the extracted complex amplitude h; 0 ≦ d <D) as the energy P _S when the DFT interval is the start point of the DFT process. and energy P _I of the interference, for example, is calculated using the following equation.

However, t _u takes to for example the following values depending on the sample point x _u of the extracted complex amplitude h _d.

Here, _{T f} is, DFT section length, _{T G} is GI length, _{t s} is the sample interval.
FIG. 7 is a conceptual diagram illustrating an example of signal energy and interference energy according to the present embodiment. In the upper part of FIG. 7, the horizontal axis indicates the discrete time n, and the vertical axis indicates the square of the absolute value of the complex amplitude | h _u | ² . In the upper part of FIG. 7, sample points that give a complex amplitude exceeding the threshold α are x ₀ , x ₁ , x _2, and x ₃ , and the square of the absolute value of the complex amplitude corresponding to x ₀ is | h ₀ | ² , x The square of the absolute value of the complex amplitude corresponding to ₁ is | h ₁ | ² , the square of the absolute value of the complex amplitude corresponding to x ₂ is | h ₂ | ² , and the square of the absolute value of the complex amplitude corresponding to x ₃ is | H ₃ | ² . Here, the SINR estimation unit 234 extracts sample points x ₀ , x ₁ , x ₂ and x ₃ that give a complex amplitude exceeding the threshold α.
In the lower part of FIG. 7, the horizontal axis represents discrete time n. Indicates. The lower part of FIG. 7 shows the signal model when the DFT timing, that is, the first sample of the DFT section (PSS) is set to the sample points x ₀ , x ₁ , x ₂ and x _{3 in} order from the upper row to the lower row. Indicates. However, the width of each column is the square of the absolute value of the complex amplitude, that is, | h ₀ | ² , | h ₁ | ² , | h ₂ | ² and | h ₃ | ² , respectively. In the example of FIG. 7, in each column, _TG is the length of two sample intervals, and _Tf is the length of five sample intervals.
Here, the SINR estimation unit 234 uses the equation (6) to calculate the signal energy P _S (x _n ) and the equation (7) to extract the interference energy P _I (x _n ) within the range of the extracted sample points. To calculate for each sample point _xn .
For example, when the DFT timing is n = x ₀ , the signal energy P _S (x ₀ ) in the path exceeding the threshold corresponds to the area of the shaded portion in the lower part of FIG. The interference energy P _I (x ₀ ) corresponds to the area of the painted portion in the lower part of FIG.

FIG. 8 is a conceptual diagram illustrating another example of signal energy and interference energy according to the present embodiment.
However, the time series of the complex amplitude | h _u | ² shown in the upper part of FIG. 8 is the same as the example shown in the upper part of FIG. The signal model shown in the lower part of FIG. 8 is the same as the example shown in the lower part of FIG.
Here, when the DFT timing and n = x _1, the signal power P _{S (x} ₁₎ in the path exceeding the threshold value corresponds to the area of the shaded portion of FIG lower. The interference energy P _I (x ₁ ) corresponds to the area of the painted portion in the lower part of FIG.

H u

^| _| 7, the complex amplitude as shown in the example of FIG. 8 the upper as long obtained square of the absolute value of ^2, similarly, SINR estimation unit 234, even in the DFT timing _{_x} n ₌ _x 2, _x ₃ , P _S (x _n ) and P _I (x _n ) can be calculated.

Next, the SINR estimation unit 234 calculates SINR using the calculated P _S (x _n ) and P _I (x _n ). The SINR at the DFT timing _xn is expressed by the following equation.

Here, N (x _n ) is noise energy in the DFT interval. The noise energy may be a value measured in advance for each temperature in the receiving apparatus 200, or may be calculated based on an OFDM symbol in a resource element to which no data signal is allocated among received signals.

The first timing detection unit 235 detects the DFT timing from the SINR for each DFT timing input from the SINR estimation unit 234, and detects the detected timing as the interference removal unit 205, the GI removal unit 206-1, and the DFT unit 207-. Output to 1. If the SINR set element output from the SINR estimation unit 234 is SINR (x _n ), the first timing determination unit 235 has a sample timing at which the SINR (x _n ) output from the SINR estimation unit 234 becomes maximum. x _n ⁽¹⁾ is determined as the DFT timing. That is, the determined timing x _n ⁽¹⁾ is expressed by the following equation.

Here, arg max _xn (...) Indicates x _n that maximizes.
For example, in the upper stage of FIG. 7, the square of the absolute value of the complex amplitude is | h ₀ | ² = 5 | h | ² , | h ₁ | ² = 10 | h | ² , | h ₂ | ² = 7 | h | ² , | h ₃ | ² = 7 | h | ² , assuming that x ₀ , x ₁ , x ₂ , and x ₃ are DFT timings, the SINR calculated by Equation (9) is x ₁ ^{( In case of 1)} , it becomes the maximum. Therefore, the sample point _{x 1} becomes the DFT timing.

Returning to FIG. 6, the timing detection unit 233-2 includes an SNR (Signal to Noise Ratio) estimation unit 236 and a second timing determination unit 237. SNR estimator 236, using the complex amplitude _{h u} input from the correlation unit 232 estimates the SNR, and outputs the estimated SNR to the second timing determination unit 237.
First, the SNR estimation unit 236 extracts sample points for estimating the SNR. Extraction of sample points, especially in sample points square becomes the maximum absolute value of the complex amplitude h _u, may be a predetermined number of points in the section, the square of the absolute value of the complex amplitude h _u is given It is good also as a sample point exceeding a threshold. Further, the threshold value may be the same as the threshold value of the SINR estimation unit, or a different threshold value may be set.
Here, similarly to the SINR estimator 234, SNR estimator 236 may extract sample points exceeding the threshold value α squared is preset absolute value of the complex amplitude h _u.
Then, SNR estimator 236, the signal energy P _S at sample points x _n of the complex amplitude h _d for each extracted sample points, for example, is calculated based on the following equation.

However, _{t n} is given by the following equation.

FIG. 9 is a conceptual diagram illustrating an example of signal energy according to the present embodiment. However, the time series of the complex amplitude | h _u | ^{2 in} the upper part of FIG. 9 is the same as the example shown in the upper part of FIG. The signal model in the lower part of FIG. 9 is the same as the example shown in the lower part of FIG.
The upper part of FIG. 9 also shows that the sample points that give the complex amplitude exceeding the threshold α are x ₀ , x ₁ , x _2, and x ₃ . Further, the SNR estimation unit 236 extracts sample points x ₀ , x ₁ , x ₂ and x ₃ that give a complex amplitude exceeding the threshold α.
The lower part of FIG. 9 shows a signal model when the DFT timing, that is, the first sample in the DFT section (PSS) is set to the sample points x ₀ , x ₁ , x ₂ and x _{3 in} order from the upper row to the lower row. Show. In the example of FIG. 9, _TG is 2 and _Tf is 5 in each column.
Here, the SNR estimation unit 236 calculates the signal energy P _S (x _n ) for each sample point x _n within the range of the extracted sample points using Expression (11).
For example, when the DFT timing is n = x ₀ , the signal energy P _S (x ₀ ) in the path exceeding the threshold corresponds to the area of the shaded portion in the lower part of FIG.

FIG. 10 is a conceptual diagram illustrating another example of signal energy according to the present embodiment. However, the time series of the complex amplitude | h _u | ^{2 in} the upper part of FIG. 10 is the same as the example shown in the upper part of FIG. The signal model in the lower part of FIG. 10 is the same as the example shown in the lower part of FIG.
Here, when the DFT timing and n = _{x 1,} the signal energy _P S _{(x 1)} in the path exceeding the threshold value corresponds to the area of FIG. 10 lower shaded portion.
8 top and as shown in the example of FIG. 9 the upper, complex amplitude _| h u ^| as long to obtain the square of the absolute value of ^2, likewise, SNR estimator 236, DFT timing _{_x} n ₌ _x 2, _x ₃ Can also calculate P _S (x _n ).

Next, the SNR estimation unit 236 calculates the SNR using the calculated P _S (x _n ). The SNR at the DFT timing _xn is expressed by the following equation.

Here, the SNR estimator 236 can provide the noise energy N (x _n ) in the same manner as the SINR estimator 234.

The second timing detection unit 237 detects the DFT timing from the SNR for each DFT timing input from the SNR estimation unit 236, and determines the detected DFT timing as the interference removal unit 205, the GI removal unit 206-2, and the DFT unit. Output to 207-2. Assuming that the SNR _n for each DFT timing input from the SNR estimation unit 236, the second timing detection unit 237 selects the DFT timing x _n ⁽²⁾ that satisfies the following expression, that is, the timing at which the SNR is maximized. .

When the complex amplitude shown in the upper part of FIG. 9 or the upper part of FIG. 10 is given, SNR ₀ is the maximum.
Therefore, the sample point x ₀ ⁽²⁾ is the DFT timing.
In the above description, the example in which the signal energy P _S (x _n ) is calculated as the DFT interval as shown in the equation (12) is shown, but not limited to this, the SNR estimation unit 236 performs the DFT described later. You may calculate based on an area. The SNR estimator 236 may calculate the signal energy P _S (x _n ) using the following equation based on, for example, DFT intervals including GI for all the reaching paths.

As described above, the synchronization unit 203 includes a plurality of timing detection units 233-β that perform timing detection based on different standards, that is, different physical quantities, threshold values, and other variables.
In the above description, the synchronization unit 203 exemplifies the case where the lengths of the DFT sections are different between the first timing detection unit 233-1 and the second timing detection unit 233-2. May be the same length.
Moreover, although the case where PSS was used was demonstrated above, in this embodiment, it is also possible to use SSS.
In the present embodiment, instead of the SINR estimation process performed by the SINR estimation unit 234 described above, SINR estimation processing for the received signal input from the reception unit 202 may be performed.
Further, in the present embodiment, instead of the SNR estimation process performed by the SNR estimation unit 236 described above, the SINR for the signal after propagation channel compensation input from the propagation channel compensation unit 208-1 or the propagation channel compensation unit 208-2. A process equivalent to the estimation process may be performed.

Returning to FIG. 5, the propagation path estimation unit 204 estimates propagation path characteristics from the transmission device 100 to the reception device 200 based on the digital signal input from the reception unit 202. The propagation path estimation unit 204 calculates propagation path characteristics from, for example, a reference signal included in the input digital signal and a reference signal stored in a storage unit included in the propagation path estimation unit 204 itself. The reference signal used for the propagation path characteristic is, for example, a signal that is assigned to the upward-sloping diagonal line portion of the OFDM signal in the resource mapping shown in FIG. The propagation path estimation unit 204 outputs the calculated propagation path characteristics to the signal detection units 221-1 and 22-1.
The signal detection unit 221-1 includes a GI removal unit 206-1, a DFT unit 207-1, and a propagation path compensation unit 208-1. The signal detection unit 221-2 includes a GI removal unit 206-2, a DFT unit 207-2, a propagation path compensation unit 208-2, and an interference removal unit 205. The signal detection unit 221-2 performs signal processing again on the reception signal that has been subjected to signal detection processing in the signal detection unit 221-1.

The interference removal unit 205 uses the propagation path characteristics input from the propagation path estimation unit 204 and the soft decision value input from the decoding unit 211 to remove interference components from the digital signal input from the reception unit 202. I do. Specifically, the interference removal unit 205 is a signal transmission source based on the soft decision value input by the decoding unit 211, that is, the LLR (Log Likelihood Ratio) of the coded bits after decoding. A signal replica estimated to be transmitted by the transmission apparatus 100 is generated. The interference removal unit 205 generates an interference replica based on the generated signal replica and the propagation path characteristics from the propagation path estimation unit 204, and subtracts the generated interference replica from the data signal input from the reception unit 202. The interference removal unit 205 outputs the residual signal obtained by this subtraction to the GI removal unit 206-2. The configuration and function of the interference removal unit 205 will be described later.

GI removal section 206-1 removes GI from the digital signal output from reception section 202, and outputs the removed signal to DFT section 207-1. GI removing section 206-2 removes GI from the residual signal output from interference removing section 205, and outputs the removed signal to DFT section 207-2. Here, the GI removal units 206-1 and 206-2 determine the GI length section as a section having a predetermined length from the DFT timing input from the synchronization unit 203.
The GI removal unit 206-1 removes the GI from the digital signal input from the reception unit 202 based on the DFT timing input from the first timing detection unit 235. That is, the GI removal unit 206-1 starts from the DFT timing input from the first timing detection unit 235 from the digital signal input from the reception unit 202, and has a preset DFT interval length T _f (data signal interval). ) Signal is extracted. For example, when DFT timing input from the first timing detecting section 235 is _{x 1,} GI removing section 206-1, a digital signal input from the reception unit 202, DFT section length starting at an _{x 1} T A signal for _f minutes is extracted. That, GI removing section 206-1, as the end point of _{x 1,} to remove a section of the GI interval length _{T G} from the beginning.
The GI removal unit 206-2 removes the GI from the residual signal input from the interference removal unit 205 based on the DFT timing input from the second timing detection unit 237. That is, the GI removal unit 206-2 uses the DFT timing input from the second timing detection unit 237 as the starting point from the residual signal input from the interference removal unit 205, and the DFT interval length T _f (data signal interval). Signal is extracted. For example, when the detection timing input from the second timing detection unit 237 is x ₀ , the GI removal unit 206-2 uses the D ₀ interval starting from x ₀ as the starting point from the residual signal input from the interference removal unit 205. A signal for the length _Tf is extracted. Here, GI removing section 206-2, as the end point of the sample points of the previous _{x 0,} removing the GI interval length _{T G} component signal.

The DFT units 207-1 and 202-1 and 2 perform Discrete Fourier Transform (DFT) for converting the signal from which the GI is input from the GI removal units 206-1 and 206-1 and 2 from a time domain signal to a frequency domain signal. The converted frequency domain signals are output to the propagation path compensators 208-1 and 208-2, respectively. That is, the DFT unit 207-1 performs DFT on the signal from which the GI input from the GI removal unit 206-1 is removed, based on the DFT timing input from the first timing detection unit 235. Based on the DFT timing input from the second timing detection unit 237, the DFT unit 207-2 performs DFT on the signal from which the GI input from the GI removal unit 206-2 is removed.
For example, if DFT timing input from the first timing detecting section 235 is _{x 1,} DFT unit 207-1, GI inputted from GI removing section 206-1 of _{x 1} as the starting point has been removed signal DFT is performed on If DFT timing input from the second timing detecting section 237 is _{x 0,} DFT section 207-2, to signal GI inputted from GI removing section 206-2 and _{x 0} as a starting point has been removed DFT is performed.
Note that the DFT unit 207-1 and the DFT unit 207-2 perform other methods, for example, fast Fourier transform (FFT), as long as the signal can be converted from the time domain to the frequency domain. May be.

The propagation path compensators 208-1 and 208-2, ZF (Zero Forcing) equalization, MMSE (Minimum Mean Square Error) equalization based on the propagation path characteristics input from the propagation path estimation unit 204. For example, a weighting coefficient for correcting propagation path distortion due to fading is calculated. The propagation path compensators 208-1 and 208-2 multiply the frequency domain signals input from the DFT sections 207-1 and 20-2 by the weighting coefficients to generate propagation path compensation signals, and demap the generated propagation path compensation signals. Output to the unit 209.
Demapping section 209 extracts data modulation symbols from the propagation path compensation signals input from propagation path compensation sections 208-1 and 208-2, and outputs the extracted data modulation symbols to demodulation section 210.

Demodulation section 210 performs demodulation processing on the data modulation symbol input from demapping section 209, and outputs a soft decision value (encoded bit LLR) to decoding section 211. The processing of the demodulation unit 210 will be described by taking the case where the data modulation method is QPSK as an example. Here, the QPSK symbol transmitted by the transmission apparatus 100 is represented by X, and the data modulation symbol input to the demodulation unit 210 is represented by Xc. Assuming that bits constituting X are b ₀ and b ₁ (b ₀ , b ₁ = ± 1), X is represented by the following expression.

However, j represents an imaginary unit. The demodulator 210 calculates a soft decision value based on Xc, that is, λ (b ₀ ) and λ (b ₁ ), which are LLRs of the bits b ₀ and b ₁ , using, for example, the following equations.

However, Re (Xc) represents the real part of the complex number Xc, and Im (Xc) represents the imaginary part of the complex number Xc. μ is an equivalent amplitude after propagation path compensation. For example, if the propagation path characteristic in the k-th subcarrier is H (k) and the propagation path distortion compensation weight coefficient calculated by the MMSE method is W (k), μ is W (k) · H (k). Note that the demodulator 210 may demodulate data modulated by another modulation scheme, for example, 16QAM, using a demodulation scheme corresponding to the modulation scheme. Demodulator 210 may output bits b ₀ and b ₁ (hard decision value) to decoding unit 211 instead of the soft decision value.

The decoding unit 211 performs error correction decoding processing on the soft decision value or hard decision value input from the demodulation unit 210, and calculates an error corrected soft decision value or hard decision value. This error correction decoding processing method is a method corresponding to error correction coding such as turbo coding and convolution coding performed by the transmission apparatus 100 as a transmission source. When transmitting apparatus 100 transmits interleaved data modulation symbols, decoding section 211 performs deinterleaving corresponding to interleaving the input soft decision value or hard decision value before performing error correction decoding processing. Process. Then, the decoding unit 211 performs error correction decoding processing on the signal that has been subjected to deinterleaving processing.
The decoding unit 211 outputs the calculated soft decision value to the interference removal unit 205. When there is no error in the information bits constituting the error-corrected soft decision value or hard decision value, or when the decoding unit 211 reaches a preset number of repetitions in an iterative process described later, the decoding unit 211 performs error correction. The information bits constituting the judgment value or the hard judgment value are output.
Further, the decoding unit 211 is a signal indicating whether or not a decoding process has been performed on the digital signal output from the receiving unit 202, a signal indicating whether or not an error has been detected in the decoding process, or an output from the receiving unit 202 A signal indicating the number of times the digital signal has been decoded is output to switching section 212. These signals are used for the above-described processing in the switching unit 212.

Next, the configuration and function of the interference removal unit 205 (FIG. 5) according to the present embodiment will be described.
FIG. 11 is a schematic diagram illustrating a configuration of the interference removal unit 205 according to the present embodiment. The interference removal unit 205 includes a replica generation unit 251 and a subtraction unit 252.
The replica generation unit 251 generates an interference component replica (interference replica) based on the propagation path characteristics input from the propagation path estimation unit 204 and the soft decision value input from the decoding unit 211.
Specifically, the replica generation unit 251 generates a signal replica that is estimated to be transmitted by the transmission apparatus 100 that is a transmission source based on the LLR of the encoded bit after decoding as a soft decision value. The replica generation unit 251 generates an interference replica using the generated signal replica and the propagation path characteristics input from the propagation path estimation unit 204, and outputs the generated interference replica to the subtraction unit 252.
The subtracting unit 252 subtracts the interference replica input from the subtracting unit 252 from the digital signal input from the receiving unit 202 to generate a residual signal. The subtraction unit 252 outputs the generated residual signal to the GI removal unit 206-2. Residual signal ^r _~ i the subtraction unit 252 outputs (t) is expressed by the following equation.

Here, r (t) is a digital signal input from the receiving unit 202. a t ≧ _{x 2.} That is, generation of the residual signal in the generation and the subtraction unit 252 of the signal replicas in the replica generation unit 251, a predetermined starting from the symbol points x ₂ represented by DFT timing inputted from the second timing detecting section 237 It is executed for the DFT interval.
r ^ _i (t) is an interference replica generated by the replica generation unit 251 in the i-th (i> 0) iteration. Here, repetition refers to repetition of processing performed by the interference removal unit 205 on the soft decision value input from the demodulation unit 211 for the digital signal input from the reception unit 202. Further, "r ^" notation "r ^~" each "^" over the letter "r" as represented in equation (19) is one which ^"~" is described . These notations also apply to “s ^”, “c ^”, and “h ^” described later.

Next, the configuration and function of the replica generation unit 251 (FIG. 11) according to the present embodiment will be described.
FIG. 12 is a schematic diagram illustrating a configuration of the replica generation unit 251 according to the present embodiment. The replica generation unit 251 includes a symbol replica generation unit 241, a mapping unit 242, an IDFT unit 243, a GI insertion unit 244, and an interference replica generation unit 245.
The symbol replica generation unit 241 generates a replica of the data modulation symbol (modulation symbol replica) based on the soft decision value (LLR of the coded bit) input from the decoding unit 211, and maps the generated modulation symbol replica to the mapping unit 242. Output to. For example, when the modulation scheme performed by the modulation unit 102 included in the transmission apparatus 100 is QPSK, the symbol replica generation unit 241 uses, for example, a modulation symbol replica expressed by the following equation based on LLR λ (b ₀ ) and λ (b ₁ ) Is generated. Here, b ₀ and b ₁ are bits constituting the QPSK modulation symbol.

Note that the symbol replica generation unit 241 may generate a modulation symbol replica not only for symbols modulated by QPSK but also for symbols modulated by other modulation schemes such as 16QAM.

Mapping section 242 arranges the modulation symbol replica input from symbol replica generation section 241 in resource elements in subcarriers arranged by resource mapping section 105 provided in transmitting apparatus 100. The mapping unit 242 outputs the signal arranged in the resource element to the IDFT unit 243. When the control signal is included in the modulation symbol replica, the mapping unit 242 may also arrange the control signal in a predetermined resource element. For example, when the subframe format of the OFDM signal received by the receiving apparatus 200 is as shown in FIG. 3, the resource element (outlined portion) in which the data modulation symbol is arranged is calculated by Expression (20). A modulation symbol replica is arranged for each data modulation symbol.

The IDFT unit 243 performs an IDFT (Inverse Discrete Fourier Transform) on the signal input from the mapping 242 to convert the frequency domain signal into a time domain signal. The IDFT unit 243 outputs the converted time domain signal to the GI insertion unit 244.
The GI insertion unit 244 adds a GI in front of the time domain signal input from the IDFT unit 243, and outputs the signal with the GI added to the interference replica generation unit 245. The signal to which the GI added by the GI insertion unit 244 is added, that is, the transmission signal replica s _{i, l} (t) of the l-th OFDM symbol in the i-th iteration is expressed by the following equation.

Here, c ^ _{i, k, l} are data modulation symbol replicas or reference symbols arranged in the kth subcarrier of the lth OFDM symbol in the i th iteration.
Interference replica generation section 245 generates an interference replica using the transmission signal replica input from GI insertion section 244 and the propagation path characteristics input from propagation path estimation section 204, and outputs the generated interference replica to subtraction section 252 To do. The interference replica is an estimated value of an interference component received until the OFDM signal transmitted from the transmission device 100 is received by the reception device 200. The symbol replica generation unit 245 generates an interference replica for each type of interference component.
There are types of interference components such as inter-symbol interference and inter-carrier interference.
For example, the interference replica generation unit 245 calculates an inter-symbol interference replica r _i (t) (t ≦ T _s , where T _s is an OFDM symbol length) in the i-th iteration using the following equation.

Here, s _{i −1} (t) represents a transmission signal replica input from the GI insertion unit in the ( _i−1 ) th repetitive processing. ＾ _d (t) is an impulse response of propagation path characteristics, and the complex amplitude of the d-th path (d-th delayed wave), t is time, τ _d is the reception time (DFT timing) of the first path (preceding wave) ) To the reception time of the d-th path, _TG is the inserted GI length. d is τ _d > T _G. When the number of iterations i = 1, s ₀ (t) becomes a soft decision value (LLR) that is an output from the decoding unit 221 based on the signal (propagation compensation signal) input from the signal detection unit 221-1. It is a data modulation replica calculated based on this. That is, the inter-symbol interference replica r _i (t) is generated from λ _i−1 which is the soft decision value (LLR) of the coded bit input from the decoding unit 211 in the _i− 1th iteration. Generated based on the signal replica s _{i -1} (t). Here, in each delayed wave that has been delayed beyond the GI length received by the receiving apparatus 200, the sum of the replicas of the portion included in the section of the OFDM symbol to be processed by DFT is the intersymbol interference replica r ^ _i. (T).
The interference replica generation unit 245 performs processing for subtracting the calculated interference replica for each OFDM symbol constituting the frame or packet to remove intersymbol interference. Note that intersymbol interference with control signals and pilot symbols can also be eliminated by executing similar processing.

Next, a reception process performed by the reception device 200 according to the present embodiment will be described.
FIG. 13 is a flowchart showing a reception process according to the present embodiment.
(Step S101) The synchronization unit 203 receives a digital signal based on the OFDM signal received by the antenna unit 201 from the reception unit 202, and detects a DFT timing (synchronization timing) using a control signal (for example, PSS). The DFT timing detected by the synchronization unit 203 includes a first synchronization timing using SINR as a detection reference and a second synchronization timing using SNR as a detection reference. For example, the timing detection unit 233-1 included in the synchronization unit 203 detects a sample point that maximizes the SINR calculated based on the input digital signal and the control signal as the first synchronization timing (DFT timing). The timing detection unit 233-2 detects a sample point that maximizes the SNR calculated based on the input digital signal and the control signal as the second synchronization timing (DFT timing).
(Step S102) The propagation path estimation unit 204 calculates propagation path characteristics based on the digital signal input from the reception unit 202 and the reference signal stored in the propagation path estimation unit 204.

(Step S <b> 103) The receiving apparatus 200 determines whether the number of repetitions i of the process performed by the interference removal unit 205 for the soft decision value input from the demodulation unit 211 is zero or greater than zero. That is, receiving apparatus 200 determines whether or not the processing for the information data signal included in the received OFDM signal is the first time. If i> 0 (Y in step S103), the switching unit 212 outputs the digital signal input from the receiving unit 202 to the signal detecting unit 221-2 (connected to a), and proceeds to step S105. If i = 0 (N in step S103), the switching unit 212 outputs the digital signal input from the receiving unit 202 to the signal detecting unit 221-1 (connected to b), and proceeds to step S104.
(Step S104) The GI removal unit 206-1 and the DFT unit 207-1 included in the signal detection unit 221-1 receive the first synchronization timing (DFT timing) from the synchronization unit 203. Thereafter, the process proceeds to step S107.
(Step S105) The interference removal unit 205, GI removal unit 206-2, and DFT unit 207-2 included in the signal detection unit 221-2 receive the second synchronization timing (DFT timing) from the synchronization unit 203. Thereafter, the process proceeds to step S106.
(Step S106) Based on the DFT timing input from the synchronization unit 203, the interference removal unit 205 subtracts the interference replica (generated in step S112) from the digital signal input from the reception unit 202 to generate a residual signal. . The interference removal unit 205 outputs the generated residual signal to the GI removal unit 206-2. Thereafter, the process proceeds to step S107.

(Step S107) GI removal sections 206-1 and 2 remove GI based on the DFT timing input from synchronization section 203 from the digital signal input from reception section 202 or the residual signal input from interference removal section 205. Then, the signal from which the GI has been removed is output to the DFT sections 207-1 and 2. The DFT sections 207-1 and 2 perform DFT on the signal (in the time domain) from which the GI input from the GI removal sections 206-1 and 2 is removed based on the DFT timing input from the synchronization section 203 (frequency domain). Convert to signal. DFT sections 207-1 and 2 perform conversion and output frequency domain signals to propagation path compensation sections 208-1 and 208-2. Thereafter, the process proceeds to step S108.

(Step S108) The propagation path compensators 208-1, 2 calculate a weighting coefficient for correcting propagation path distortion based on the propagation path characteristics input from the propagation path estimation unit 204. The propagation path compensators 208-1 and 2 multiply the calculated weighting factor by the frequency domain signal input from the DFT sections 207-1 and 2 to generate a propagation path compensation signal, and degenerate the generated propagation path compensation signal. The data is output to the mapping unit 209. Thereafter, the process proceeds to step S109.
(Step S109) The demapping unit 209 extracts a data modulation symbol from the channel compensation signals input from the channel compensation units 208-1 and 208-2, and outputs the extracted data modulation symbol to the demodulation unit 210. Demodulation section 210 performs demodulation processing on the data modulation symbol input from demapping section 209, and outputs a soft decision value (encoded bit LLR) to decoding section 211. Then, it progresses to step S110.

(Step S110) The decoding unit 211 performs error correction decoding processing on the soft decision value input from the demodulation unit 210, calculates an error corrected soft decision value, and determines whether there is a data error. If it is determined that there is a data error (Y in step S110), the process proceeds to step S111. When it is determined that there is no data error (N in step S110), the decoding unit 211 outputs the soft decision value in which the error is corrected, and ends the process. Then, receiving apparatus 200 waits for reception of the next received signal.
(Step S111) The receiving apparatus 200 determines whether or not the number of repetitions i of the processing performed by the interference removal unit 205 for the soft decision value input from the demodulation unit 211 has reached a preset number of repetitions M. To do. When the receiving apparatus 200 determines that the number of repetitions i of the process performed by the interference removal unit 205 with respect to the soft decision value input from the demodulation unit 211 has reached a preset number of repetitions M (step S111 Y) Then, the demodulator 211 outputs the soft decision value that has been error-corrected, and ends the process. Then, receiving apparatus 200 waits for reception of the next received signal. When it is determined that the number of repetitions i of the processing performed by the interference removal unit 205 is less than the preset number of repetitions M (N in step S111), the process proceeds to step S112.
(Step S112) The interference removal unit 205 generates an interference replica based on the propagation path characteristics input from the propagation path estimation unit 204 and the soft decision value input from the decoding unit 211. Thereafter, the process proceeds to step S105.

As described above, in the first embodiment, the signal detection unit 221-1 that does not include the interference removal unit 205 is based on the timing estimated based on the SINR that is the ratio of the signal power to the interference and noise power. Perform each process. Thereby, the data signal section based on the timing setting in consideration of the interference caused by the delay path exceeding the GI length can be determined. On the other hand, the signal detection unit 221-2 provided with the interference removal unit 205 removes the interference and performs GI removal, DFT, propagation path based on the timing estimated based on the SNR that is the ratio of the signal power and the noise power. Perform each compensation process. As described above, since the receiving apparatus performs the decoding process on the signal in the data signal section determined by different criteria (for example, reception power or interference amount), the receiving apparatus can obtain good reception characteristics.
In the above-described example, this embodiment has been described as having the function of removing the intersymbol interference by the interference removal unit 205. However, in this embodiment, other interference components such as inter-carrier interference are used instead. You may provide the function to remove.
Even if the interference removal method is different from the method of calculating the inter-symbol interference replica (for example, Equation (21), Equation (22)) as described above and subtracting this, the interference removal unit 205 performs decoding. Feedback such as a soft decision value may be input from a part or the like.
In the above example, the case where the transmission apparatus is SISO (Single Input Single Output) has been described. However, in the present embodiment, the transmission apparatus may be a MIMO (Multi Input Multi Output).

(Second Embodiment)
The second embodiment will be described below with reference to the drawings.
FIG. 14 is a schematic diagram illustrating a configuration of the synchronization unit 303 according to the present embodiment. The receiving apparatus according to the present embodiment includes a synchronizing unit 303 instead of the synchronizing unit 203 in the receiving apparatus 200 according to the first embodiment. Hereinafter, differences from the first embodiment will be mainly described.
The synchronization unit 303 includes a filter unit 231, a correlation unit 232, and timing detection units 233-1 and 333-2. That is, the synchronization unit 303 includes a timing detection unit 333-2 instead of the timing detection unit 233-2 of the synchronization unit 203 according to the first embodiment.
The timing detection unit 333-2 includes a power estimation unit 336 and a second timing determination unit 337. The power estimation unit 336 estimates the power of the received signal based on the complex amplitude input from the correlation unit 232, and outputs the estimated power to the second timing determination unit 337. The power estimation unit 336 uses, for example, Expression (11) or Expression (15) in order to estimate the power of the received signal. In addition, the power estimation unit 336 may include an RSSI (Received Signal Strength Indicator). In that case, the power estimation unit 336 estimates the power of the reception signal based on the digital signal directly input from the reception unit 202.

Second timing determination section 337 detects DFT timing based on the power of the received signal input from power estimation section 336. That is, the second timing determination unit 337 determines the sample point x2 _{, n at} which the power Power _n of the received signal of sample n input from the power estimation unit 336 is the maximum as the DFT timing.
For example, when the complex amplitude shown in the upper part of FIG. 7 or the upper part of FIG. 8 is given, the second timing determination unit 337 has the area of the shaded part in the lower part of FIG. 7 or the lower part of FIG. . 7 and 8, the second timing determination unit 337 determines the area of the hatched portion, that is, the sample point _{x2,0 at} which the power of the received signal is maximum, as the DFT timing.
Note that sample points x2 _{, n at} which the power Power _n of the received signal is maximum may be determined as the DFT timing, corresponding to the area of the shaded portion in the lower part of FIG. 9 or the lower part of FIG. Second timing determination section 337 outputs the determined DFT timing to interference cancellation section 205, GI cancellation section 206-2, and DFT section 207-2. The interference removal unit 205 performs interference removal based on the DFT timing input from the second timing determination unit 337. The GI removal unit 206-2 performs GI removal based on the DFT timing input from the second timing determination unit 337. The DFT unit 207 performs DFT based on the DFT timing input from the second timing determination unit 337.

As described above, in the present embodiment, the signal detection unit 221-2 including the interference removal unit 205 determines the data signal interval based on the DFT timing estimated with the received power as a reference. Thereby, the timing can be determined in consideration of the interference processing performed in the interference removal unit 205. As described above, in the present embodiment, the data signal interval is determined based on the timing estimated using different criteria for SINR and received power in the processing in the plurality of signal detection units. In the present embodiment, since the data signal in this section is decoded, it is possible for the receiving apparatus 200 to obtain good reception characteristics.

(Third embodiment)
The third embodiment will be described below with reference to the drawings.
FIG. 15 is a schematic diagram illustrating a configuration of the synchronization unit 403 according to the present embodiment. The receiving apparatus according to the present embodiment includes a synchronization unit 403 instead of the synchronization unit 203 in the receiving apparatus 200 according to the first embodiment. Hereinafter, differences from the first embodiment will be mainly described.
The synchronization unit 403 includes a filter unit 231, a correlation unit 232, and timing detection units 233-1 and 433-2. That is, the synchronization unit 403 includes a timing detection unit 433-2 instead of the timing detection unit 233-2 of the synchronization unit 203 according to the first embodiment.
The timing detection unit 433-2 includes a path search unit 436 and a second timing determination unit 437. The path search unit 436 estimates the arrival path based on the complex amplitude input from the correlation unit 232, and outputs the estimated arrival path and its sample point to the second timing determination unit 437. For example, the path search unit 436 estimates a complex amplitude whose square of the absolute value of the complex amplitude input from the correlation unit 232 is equal to or greater than a predetermined threshold α as an arrival path, and determines a sample point related to the arrival path.
The second timing determination unit 437 determines the earliest sample point of the complex amplitude sample points estimated as the incoming path input from the path search unit 436 as the DFT timing. For example, when | h ₀ |, | h ₁ |, | h ₂ |, and | h ₃ | are estimated as arrival paths as shown in the upper part of FIG. 6, the second timing determination unit 437 first appears | The sample point x ₀ of h ₀ | becomes the DFT timing.

The second timing determining unit 437 outputs the determined DFT timing to the interference removing unit 205, the GI removing unit 206-2, and the DFT unit 207-2. The interference removal unit 205 performs interference removal based on the DFT timing input from the second timing determination unit 437. The GI removal unit 206-2 performs GI removal based on the DFT timing input from the second timing determination unit 437. The DFT unit 207 performs DFT based on the DFT timing input from the second timing determination unit 437.

As described above, in the present embodiment, the signal detection unit 221-2 including the interference removal unit 205 performs each process based on the DFT timing estimated based on the arrival path sample point (arrival time). Thereby, signal detection processing using all effective arrival paths becomes possible. As described above, in the present embodiment, the data signal section is determined based on the timing detected by the plurality of signal detection units using the SINR and the reference different from the arrival path. In the present embodiment, since the data signal in this section is decoded, it is possible for the receiving apparatus 200 to obtain good reception characteristics.

(Fourth embodiment)
Hereinafter, a fourth embodiment will be described with reference to the drawings.
FIG. 16 is a schematic diagram illustrating a configuration of the synchronization unit 503 according to the present embodiment. The receiving apparatus according to the present embodiment includes a synchronization unit 503 instead of the synchronization unit 203 in the receiving apparatus 200 according to the first embodiment. Hereinafter, differences from the first embodiment will be mainly described.
The synchronization unit 503 includes a filter unit 231, a correlation unit 232, and timing detection units 533-1 and 233-2. That is, the synchronization unit 433 includes a timing detection unit 533-1 instead of the timing detection unit 233-1 of the synchronization unit 203 according to the first embodiment.
The filter unit 231 outputs the band component signal to the DFT unit 542 (described later) included in the timing detection unit 533-1.

FIG. 17 is a schematic diagram illustrating a configuration of the timing detection unit 533-1 according to the present embodiment.
The timing detection unit 533-1 includes a path search unit 541, a DFT unit 542, a demodulation unit 543, and a determination unit 544.
The path search unit 541 estimates the arrival path based on the complex amplitude input from the correlation unit 232 and outputs the estimated arrival path sample points to the DFT unit 542. Here, the path search unit 541 estimates a complex amplitude in which the square of the absolute value of the complex amplitude input from the correlation unit 232 is greater than a preset threshold value α as an incoming path, and sets a sample point related to the complex amplitude as a sample point. The arrival time of the arrival path is determined. For example, as shown in FIG. 7 upper _{_{| h 0 |, | h 1}} |, | h 2 |, | h 3 | If is presumed arrival path, the sample point at which the arrival time is _x _{0, x} 1, the _x _2, x _3.

The DFT unit 542 receives sample points from the path search unit 541 and receives band component signals from the filter unit 231. The DFT unit 542 sets the input sample points to the OFDM symbol in which the synchronization signal included in the input band component signal is arranged in the DFT section set in advance as the head of the DFT section, that is, as the DFT point. Then, DFT is performed to convert the signal into a frequency band component signal. The DFT unit 542 outputs the converted frequency band component signal to the demodulation unit 543.
Demodulation section 543 extracts a subcarrier component to which a synchronization signal is assigned from the frequency band component signal input from DFT section 542, and demodulates the extracted component to generate a demodulated signal. The demodulation process performed by the demodulation unit 543 is a demodulation process corresponding to the modulation process performed by the control signal generation unit 103 included in the transmission device 100. Demodulation section 543 outputs the generated demodulated signal to determination section 544.
The determination unit 544 compares the control signal sequence included in the demodulated signal input from the demodulation unit 543 with the control signal (for example, PSS) used for the synchronization process stored in the storage area of the determination unit 544, and determines an error. And the error rate is calculated based on the detected error frequency.
For example, when an OFDM symbol is input in the format shown in FIG. 4, since PSS is assigned as a control signal to 63 subcarriers, the determination unit 544 detects an error every 63 bits, and determines the number of detected errors. The error rate is calculated based on the number of bits 63 included in each frame.

The DFT in the DFT unit 542, the demodulation processing in the demodulation unit 543, and the error rate calculation in the determination unit 544 are performed for each sample point included in the DFT interval. Returning to FIG. 16, the first timing detector 533-1 determines the sample point at which the calculated error rate is the smallest as the DFT timing. In addition, the timing detection unit 533-1 may determine the sample point with the smallest number of errors as the DFT timing. The timing detection unit 533-1 outputs the determined DFT timing to the GI removal unit 206-1 and the DFT unit 207-1. The GI removal unit 206-1 performs GI removal based on the DFT timing input from the timing detection unit 533-1. The DFT unit 207-1 performs DFT based on the DFT timing input from the timing determination unit 533-1. Note that the receiving apparatus 200 according to the present embodiment includes the timing detection unit 333-2 of the second embodiment or the timing detection unit 433-2 of the third embodiment instead of the timing detection unit 233-2. Also good.

As described above, in this embodiment, the signal detection unit 221-1 that does not include the interference removal unit 205 performs each process based on the DFT timing estimated based on the error rate of the synchronization signal. Thereby, the DFT timing can be estimated in consideration of interference caused by a delay path exceeding the GI length. As described above, in the present embodiment, the data signal section is determined based on the timing estimated by using a reference different from the error rate and the SNR in the plurality of signal detection units. According to the present embodiment, since the signal in this section is decoded, the reception device 200 can obtain good reception characteristics.

(Fifth embodiment)
Hereinafter, a fifth embodiment will be described with reference to the drawings.
FIG. 18 is a schematic diagram illustrating a configuration of a transmission device 700 according to the fifth embodiment of the present invention.
Transmitting apparatus 700 includes coding sections 101-1 to 101-N _T (N _T is the spatial multiplexing number), modulation sections 102-1 to 102-N _T , control signal generation sections 103-1 to 103-N _T , reference signals Generation units 104-1 to 104-N _T , resource mapping units 105-1 to 105-N _T , IDFT units 106-1 to 106-N _T , GI insertion units 107-1 to 107-N _T , and transmission unit 108- 1 ~ _{108-N T} and configured to include the antenna section 109-1 ~ _{109-N T.}
The transmission apparatus 700 includes encoders 101-1 to 101-N _T , modulators 102-1 to 102-N _T , control signal generators 103-1 to 103-N _T , and reference signal generator 104-1. 104-N _T , resource mapping units 105-1 to 105-N _T , IDFT units 106-1 to 106-N _T , GI insertion units 107-1 to 107-N _T , and transmission units 108-1 to 108-N _{The T} and antenna units 109-1 to 109-N _T are provided in the transmission apparatus 100. The encoding unit 101, the modulation unit 102, the control signal generation unit 103, the reference signal generation unit 104, the resource mapping unit 105, and the IDFT unit 106 , The GI insertion unit 107, the transmission unit 108, and the antenna unit 109 have the same configuration and function. However, different pieces of information data are input to the encoding units 101-1 to 101- _NT included in the transmission apparatus. Also, different control data is input to each of the control signal generators 103-1 to 103- _NT . Hereinafter, the present embodiment will be described focusing on the differences from the first embodiment.

Transmitting sections 108-1 to 108- _NT simultaneously transmit the generated OFDM signals from antennas 109-1 to 109- _NT by radio waves to receiving apparatus 600. The transmission apparatus 700 performs SIS0 (Single Input, Single Output) transmission when the number of antennas 109, that is, the number of spatial multiplexing n = 1, and MIMO (Multiple Input, Multiple Output) transmission when n = 2 or more. In MIMO transmission, a signal output from each antenna is called a stream.
Here, the signals s _{l, n} (t) of the l-th OFDM symbol output from the GI insertion units 107-1 to 107- _NT are expressed by the following equations.

Here, C _{k, l, n} are data modulation symbols assigned to the kth subcarrier of the lth OFDM symbol output from antenna 109-n (n = 1,..., N _T ), Control signal or reference signal.
In the following description, the signals output from the antennas 109-1 to 109- _NT are described as following the formats of FIGS. 3 and 4, but the present invention is not limited to this. Note that the control signals (for example, PSS and SSS) may be arranged in any of the OFDM signals output from the antennas 109-1 to 109- _NT .
In the example shown in FIG. 18, the resource mapping units 105-1 to 105-N _T assign control signals input from the control signal generation units 103-1 to 103-N _T for each stream. However, in this embodiment, a control signal based on control data for other streams may be assigned to only a predetermined part of the streams.

Next, the receiving apparatus 600 according to the present embodiment will be described.
FIG. 19 is a schematic diagram illustrating a configuration of a receiving device 600 according to the present embodiment. Receiving device 600 includes antenna units 201-1 to 201-N _R (N _R is the number of receiving antennas), receiving unit 202, synchronization unit 603, propagation path estimation unit 204, signal detection units 621-1 to 621-3), Demapping units 209-1 to 209-N _T , demodulation units 210-1 to 210-N _T, decoding units 211-1 to 211-N _T , and a switching unit 612 are included.
Antenna units 201-1 to 201-N _R provided in receiving apparatus 600, receiving unit 202, synchronizing unit 203, propagation path estimating unit 204, signal detecting units 621-1 and 621-2, and demapping units 209-1 to 209- N _T , demodulation units 210-1 to 210 -N _T and decoding units 211-1 to 211 -N _T are provided in the reception apparatus 200, including an antenna unit 201, a reception unit 202, a synchronization unit 203, a propagation path estimation unit 204, Each of the signal detection units 221-1 and 221-2, the demapping unit 209, the demodulation unit 210, and the decoding unit 211 has the same configuration and function. Note that the difference between the receiving apparatus 600 according to the present embodiment and the receiving apparatus 100 according to the first embodiment will be mainly described.

Receiving unit 202 is input an OFDM signal transmitted from the transmitter 700 to the antenna unit 201-1 ~ _{201-N R} received, digital signal processing the input OFDM signal is down-converted to a frequency band available. The receiving unit 202 performs filtering processing on the down-converted signal to remove unnecessary components, and converts the filtered signal from an analog signal to a digital signal (A / D conversion). The reception unit 202 outputs the converted digital signal to the propagation path estimation unit 204, the synchronization unit 603, and the signal detection units 621-1 to 621-3.
The synchronization unit 603 calculates a correlation value from the control signal included in the digital signal input from the reception unit and the control signal stored in the storage area included in the synchronization unit 603, and detects the DFT timing based on the calculated correlation value. The synchronization unit 603 uses the detected DFT timings as signal detection units 621-1 to 621-3, that is, the interference removal unit 205, the GI removal units 206-1 to 206-3, the DFT units 207-1 to 207-3, the propagation path The data is output to the compensation units 608-1 and 608-2 and the maximum likelihood detection unit 610. The synchronization unit 603 outputs the calculated correlation value to the switching unit 612.
The propagation path estimation unit 204 estimates propagation path characteristics from the antenna units 109-1 to 109- _NT of the transmission apparatus 700 to the antenna units 201-1 to 201-N _R of the reception apparatus 600, and the estimated propagation path The characteristics are output to the signal detectors 621-1 to 621-3. The propagation path characteristic represents variation in amplitude and phase due to fading between the antenna unit 109-1 ~ _{109-N T} and the antenna unit 201-1 ~ _{201-N R.} Here, the propagation path estimation unit 204 sets the propagation path characteristic to, for example, the reference signal included in the digital signal input from the reception unit 202 (for example, the rightward of the OFDM signals indicated by the resource mapping shown in FIG. 4). And a reference signal stored in a storage area provided by itself.

The switching unit 612 receives the digital signal input from the receiving unit as a signal detection unit 621-1 (connected to b), a signal detection unit 621-2 (connected to c), or a signal detection unit 621-3 (connected to a) Output to. Switching unit 612, the signal is input to these destinations from decoding section 211-1 ~ _{211-N T,} or for example, is input from the synchronization unit 603, switching unit 612, the correlation value synchronization unit 603 is calculated ( When a delay path exceeding the GI length is detected in the delay profile), the receiving apparatus 600 outputs the digital signal input from the receiving unit 202 to the signal detecting units 621-1 and 621-2 (connected to b and c). ).
Further, the switching unit 612 outputs the digital signal input from the receiving unit 202 to the signal detecting unit 621-2 when the digital signal output from the receiving unit 202 is decoded one or more times by the decoding unit 211. (Connect to c).
On the other hand, the switching unit 612, if the digital signal output from the receiving unit 202 also decoding is not performed once by the decoding unit 211-1 ~ _{211-N T,} a digital signal input from the reception unit 202 The signal is output to the signal detector 621-1 (connected to b).
In addition, the switching unit 612 does not detect a delay path exceeding the GI length in the correlation value (delay profile) input from the synchronization unit 603 and the input from the reception unit 202 when the spatial multiplexing number n is less than 2. The digital signal thus output is output to the signal detector 621-1 (connected to b).
In addition, the switching unit 612 does not detect a delay path exceeding the GI length in the correlation value input from the synchronization unit 603, and if the spatial multiplexing number n is 2 or more, the switching unit 612 converts the input digital signal into a signal detection unit Output to 621-3 (connected to a).
The spatial multiplexing number n is a part of the control information of the control signal included in the OFDM signal transmitted by the transmitting apparatus 700, and the switching unit 612 extracts the spatial multiplexing number n from the digital signal input from the receiving unit 202. To do.

Each of the signal detection units 621-1 to 621-3 includes GI removal units 206-1 to 206-3 and DFT units 207-1 to 207-3. Also, the GI removal units 206-1 to 206-3 and the DFT units 207-1 to 207-3 have the same configurations and functions as the GI removal unit 206 and the DFT unit 207 of the receiving apparatus, respectively.
The signal detection unit 621-1 includes a propagation path estimation unit 608-1 in addition to the GI removal unit 206-1 and the DFT unit 207-1.
The removal of the GI length section performed by the GI removal unit 206-1 and the DFT performed by the DFT unit 207-1 are set in advance starting from the DFT timing input from the first timing detection unit provided in the synchronization unit 603. This is performed for the section of the FFT section length _Tf .
Output signals R 1 ^to _{k, l} in the k-th subcarrier of the l-th OFDM symbol output from DFT section 207-1 are expressed by the following equations.

Here, R 1 ^to _{k, l} are N elements having outputs R 1 ^to _{k, l and m} from the DFT units 207-1 to 207-3 for each antenna 201-m (m = 1,..., N _R ) as elements. vector of the _R column ^{_{^{_{[R ~ k, l, 1}}}} ... R ~ k, l, NR] is ^T. H _{k, l} is a matrix of N _R × N _T expressed by the following equation having propagation path characteristics (frequency response) H _{k, l, mn} from the antenna 109-n to the antenna 201-m.

S _{k, l} is the modulation symbol _{c k} output from the modulating unit 102-n of the transmission device _{700, l,} _N and the _n elements _T columns of the vector _{_{[c k, l, 1 ...}} c k, l, NT] T It is. N _{k, l} is an N _R × 1 vector [N _{k, l, 1} ... N _{k, l, NR} ] ^T having noise components N _{k, l, m} for each antenna 201-m as elements.

The propagation path compensation unit 608-1 calculates a weighting factor for correcting the propagation path distortion based on the propagation path characteristic input from the propagation path estimation unit 204, and the calculated weighting factor is a frequency domain signal input from the DFT unit 207. To generate a propagation path compensation signal.
As a method of calculating the weighting factor by the propagation path compensation unit 608-1, for example, ZF (Zero Forcing) and MMSE (Minimum Mean Square Error) can be used as in the propagation path compensation unit 208-α.
Here, when the frequency domain signal input from DFT section 207-1 is a spatially multiplexed signal (MIMO signal) (n = 2 or more), MIMO separation processing is performed to detect modulation symbols _{Sk, l} To do. The propagation path compensation unit 608-1, for example, multiplies the ZF weight coefficient matrix M _{ZF, k} calculated using the following equation as the MIMO separation processing by ZF from the left of the vectors R 1 ^to _{K, l} , and modulates the modulation symbol S _{k , L} are detected.

The propagation path compensation unit 608-1, for example, multiplies the MMSE weight coefficient M _{MMSE, k} calculated using the following equation as the MIMO separation processing based on the MMSE standard from the left of the vectors R 1 ^to _{k, l} , and modulates the modulation symbol S _{k. , L} may be detected.

Where ^H is the complex conjugate transpose of the matrix, ⁻¹ is the inverse matrix, σ _N is the noise power, and I is the unit matrix.
The signal detection unit 621-2 includes an interference removal unit 605, a GI removal unit 206-2, a DFT unit 207-2, and a propagation path estimation unit 608-2.
The GI length section removal performed by the GI removal section 206-2 and the DFT performed by the DFT section 207-2 are FFT section lengths T starting from the DFT timing input from the second timing detection section provided in the synchronization section 603. _This is performed for the interval _f .
The interference canceller 205 receives the propagation path characteristic input from the propagation path compensator 204 and the input from the decoder 211-n from the digital signal based on the MIMO signal (spatial multiplexing number n = 2 or more) input from the receiver 202. An interference component is removed using the determined soft decision value. The interference removal unit 605 outputs the residual signal obtained by removing the interference component to the GI removal unit 206-2. Note that the interference removal unit 205 may remove a signal of another stream that is an interference component from a signal of a certain stream that constitutes the MIMO signal. For example, the interference removal unit 205 may remove the stream 2 to _NT signals received from the antennas 109-2 to 109- _NT from the stream 1 signal received from the antenna 109-1.
In order to remove the signals of other streams, the subtraction unit 252 included in the interference removal unit 205 subtracts the interference replica of a certain stream and the replica of the other stream from the signal of the certain stream. The replica generation unit 251 included in the interference removal unit 205 uses the propagation path characteristics input from the propagation path estimation unit 204 and the soft decision values for other streams to perform replicas of other streams by processing similar to the interference replica. Generate.

The signal detection unit 621-3 includes a GI removal unit 206-3, a DFT unit 207-3, and a maximum likelihood detection unit 610.
The removal of the GI length section performed by the GI removal unit 206-3 and the DFT performed by the DFT unit 207-3 are performed based on the DFT timing input from the first timing detection unit included in the synchronization unit 603.
The maximum likelihood detection unit 610 performs maximum likelihood detection on a portion based on information data in the frequency domain signal input from the DFT unit 207-3, and calculates a bit log likelihood ratio for each stream. The maximum likelihood detection unit 610 outputs the calculated bit log likelihood ratio for each stream to the decoding unit 211-n. Here, the bit sequence β _{k, l} of the information data included in the modulation symbol S _{k, l} is represented by [b _{k, l, 1,0} ... b _{k, l, 1, M-1} ... b _{k, l, NT , M−1} ]. M is a modulation multi-level number. For example, M = 2 for the modulation scheme QPSK and M = 4 for 16QAM. Further, b _{k, l, t, and q} represent the q-th bit of the t-th stream constituting the information data. In the following description, the subscript l indicating the symbol and the subscript k indicating the subcarrier are omitted. That is, β _{k, l} is expressed as β, b _{k, l,} _{t, q} is expressed as b _{t, q} .
The maximum likelihood detection unit 610 calculates the bit log likelihood ratio λ (b _{t, q} ) of the bits b _{t, q} using, for example, the following equation.

Demapping section 209-1 ~ _{209-N T} extracts data modulation symbols from the channel compensation signal input from the channel compensation unit 608-1,608-2, demodulates the extracted data modulation symbol unit 210- Output to 1-210- _NT .
Demodulation sections 210-1 to 210- _NT perform demodulation processing on the data modulation symbols input from demapping sections 209-1 to 209- _NT , calculate soft decision values, and calculate soft decision values. It is output to the decoding unit 211-1 ~ _{211-N T.} When the number of spatial multiplexing is 2 or more, demapping processing in demapping sections 209-1 to 209- _NT and demodulation processing in demodulation sections 210-1 to 210- _NT are performed for each stream.
Decoding sections 211-1 to 211 -N _T perform error correction decoding processing on soft decision values input from demodulation sections 210-1 to 210 -N _T , and eliminate interference of soft correction values corrected for errors The data is output to the unit 205. Further, the decoding unit 211-1 ~ 211-N _T, if no error is the information bits after error correction decoding, or when the iteration process reaches a preset number of iterations, the information a soft decision value obtained by the error correction Output as data.
Further, the decoding unit 211-1 ~ 211-N _T, a signal indicating whether or not subjected to decoding processing to the digital signal output from the receiving unit 202, a signal indicating whether an error is detected in the decoding process, or Signals indicating the number of times the decoding process is performed on the digital signal output from the receiving unit 202 are output to the switching unit 612, respectively. These signals are used by the switching unit 612 for the above-described processing.

As described above, in the present embodiment, the signal detection units 621-1 and 621-3 perform signal detection processing based on the first DFT timing input from the synchronization unit 203, and the signal detection unit 621-2. Performs signal detection processing based on the second DFT timing input from the synchronization unit 203. That is, in the receiving apparatus 600 in the present embodiment, each signal detection unit determines each data signal section based on one of a plurality of different references, for example, timings detected by SINR and SNR. By decoding the data section of this section, the receiving apparatus 600 according to the present embodiment can obtain good reception characteristics.
In addition, even if precoding, spreading, and the like are performed on the signals transmitted by the transmission apparatuses 100 and 700 in the above-described embodiment, the same applies.

Note that a part of the receiving devices 200 and 600 or the transmitting devices 100 and 700 in the above-described embodiment, for example, the encoding units 101, 101-1 to 101-N _T , the modulation units 102, 102-1 to 102-N _T , Control signal generators 103, 103-1 to 103-N _T , reference signal generators 104, 104-1 to 104-N _T , resource mapping units 105, 105-1 to 105-N _T , IDFT units 106 and 106- 1 to 106-N _T , GI insertion unit 107, 107-1 to 107-N _T , synchronization unit 203, propagation path estimation unit 204, signal detection units 211-1, 211-2, 621-1 to 621-3, Demapping units 209, 209-1 to 209-N _T , demodulating units 210, 210-1 to 210-N _T , and decoding units 211, 211-1 to 211-N _T are realized by a computer You may make it do. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by a computer system and executed.
Here, the “computer system” is a computer system built in the receiving devices 200 and 600 or the transmitting devices 100 and 700 and includes hardware such as an OS and peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM or a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In such a case, a volatile memory inside a computer system serving as a server or a client may be included and a program that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.
In addition, a part or all of the receiving devices 200 and 600 and the transmitting devices 100 and 700 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the receiving devices 200 and 600 and the transmitting devices 100 and 700 may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, in the case where an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology may be used.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to that described above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

As described above, the receiving apparatus, receiving method, receiving program, and communication system according to the present invention are useful for wireless communication, and are particularly suitable for mobile communication such as a mobile phone.

100, 700 ... transmitting device,
101, 101-1 to 101-N _T ... code part,
102, 102-1 to 102-N _T ... modulation unit,
103, 103-1 to 103-N _T ... control signal generation unit,
104, 104-1 to 104-N _T ... Reference signal generator,
105, 105-1 to 105-N _T ... Resource mapping unit,
106, 106-1 to 206-N _T IDFT section,
107, 107-1 to 107-N _T , 244... GI insertion part,
108, 108-1 to 108-N _T ... transmission unit,
109, 109-1 to 109-N _T ... antenna part,
200, 600 ... receiving device,
201, 201-1 to 201-N _R ... antenna unit, 202 ... receiving unit, 203, 303, 403, 503,603 ... synchronizing unit,
204 ... propagation path estimation unit, 205 ... interference removal unit,
206-1 to 206-3 ... GI removal unit,
207-1 to 207-3, 542 ... DFT section,
208-1, 208-2, 608-1, 608-2 ... propagation path compensation unit,
209, 209-1 to 209-N _T ... demapping unit,
210, 210-1 to 210-N _T , 543 ... demodulator,
211, 211-1 to 211-N _T ... decoding unit, 212, 612 ... switching unit, 221-1, 221-2, 621-1 to 621-3 ... signal detection unit,
231 ... Filter unit, 232 ... Correlation unit,
233-1, 233-2, 333-2, 433-2, 533-1... Timing detection unit,
234 ... SINR estimation unit, 235 ... first timing determination unit,
236 ... SNR estimation unit, 237, 337, 437 ... second timing determination unit,
241 ... Symbol replica generation unit, 242 ... Mapping unit, 243 ... IDFT unit,
244 ... GI insertion unit, 245 ... interference replica generation unit,
251 ... Replica generation unit, 252 ... Subtraction unit,
336 ... power estimation unit, 436, 541 ... path search unit, 544 ... determination unit,
610 ... Maximum likelihood detection unit

Claims

A receiver for receiving the signal;
A plurality of signal detectors that extract a signal of a predetermined length from the received signal;
A decoding unit for decoding the signal of the extracted section;
A synchronization unit for detecting a plurality of timings based on different references from the received signal;
With
Each of the signal detection units determines a section for extracting a signal using one of the detected timings;
A receiver characterized by.
The plurality of signal detection units include a first signal detection unit and a second signal detection unit,
The first signal detection unit includes:
A time frequency conversion unit for converting the received signal from the time domain to the frequency domain;
The second signal detector is
An interference cancellation unit that generates a residual signal by removing an interference replica generated based on the signal decoded by the decoding unit from the received signal;
A time frequency conversion unit for converting the residual signal from the time domain to the frequency domain,
The first signal detection unit and the second signal detection unit each define a section for extracting a signal using different timings;
The receiving apparatus according to claim 1.
The first signal detector performs processing on the received signal,
Thereafter, the second signal detector repeats until a predetermined condition is satisfied,
The receiving device according to claim 2.
The receiving apparatus according to claim 1, wherein the synchronization unit detects the timing based on a signal-to-interference noise ratio of the received signal as one of the references.
The receiving apparatus according to claim 4, wherein the synchronization unit detects a timing at which the signal-to-interference noise ratio is maximized.
The synchronization unit detects the timing based on a signal-to-interference noise ratio of the received signal as one of the criteria,
The receiving apparatus according to claim 2, wherein the first signal detection unit determines a section in which a signal is extracted based on the detected timing.
The receiving apparatus according to claim 1, wherein the synchronization unit detects the timing based on a signal-to-noise ratio of the received signal as one of the references.
The receiving apparatus according to claim 7, wherein the synchronization unit detects a timing at which the signal-to-noise ratio is maximized.
The synchronization unit detects the timing based on a signal-to-noise ratio of the received signal as one of the criteria,
The receiving apparatus according to claim 2, wherein the second signal detection unit determines a section in which a signal is extracted based on the detected timing.
The receiving apparatus according to claim 1, wherein the synchronization unit detects the timing based on power of the received signal as one of the references.
The receiving apparatus according to claim 10, wherein the synchronization unit detects a timing at which the power of the received signal becomes maximum.
The synchronization unit detects the timing based on the power of the received signal as one of the references,
The receiving apparatus according to claim 2, wherein the second signal detection unit determines a section in which a signal is extracted based on the detected timing.
The receiving apparatus according to claim 1, wherein the synchronization unit detects the timing based on an arrival path of the received signal as one of the references.
The receiving apparatus according to claim 13, wherein the synchronization unit detects a timing at which the arrival path first arrives.
The synchronization unit detects the timing based on an incoming path of the received signal as one of the references,
The receiving apparatus according to claim 2, wherein the second signal detection unit determines a section in which a signal is extracted based on the detected timing.
The receiving apparatus according to claim 1, wherein the synchronization unit detects the timing based on an error frequency of the decoded signal as one of the references.
The receiving apparatus according to claim 16, wherein the synchronization unit detects a timing at which the error frequency is minimized.
The synchronization unit detects the timing based on an error frequency of the decoded signal as one of the criteria,
The receiving apparatus according to claim 2, wherein the second signal detection unit determines a section in which a signal is extracted based on the detected timing.
The synchronization unit detects the timing based on a signal-to-noise ratio of the received signal as one of the criteria,
The receiving apparatus according to claim 2, wherein the first signal detection unit determines a section in which a signal is extracted based on the detected timing.
A receiving method in a receiving device,
A first process in which the receiving device receives a signal;
A plurality of second processes in which the receiving device extracts a signal having a predetermined length from the received signal;
A third process in which the receiving device decodes the signal of the extracted section;
A fourth process in which the receiving device detects a plurality of timings based on different criteria from the received signal, respectively.
Each of the plurality of second processes defines a section in which a signal is extracted using one of the detected plurality of timings;
A receiving method characterized by the above.
In the computer provided in the receiving device,
A first procedure for receiving a signal;
A plurality of second procedures for extracting a signal having a predetermined length from the received signal;
A third procedure for decoding the signal of the extracted section;
A reception program for executing a fourth procedure for detecting a plurality of timings based on different references from the received signal,
Each of the plurality of second procedures defines an interval for extracting a signal using one of the detected plurality of timings;
A receiving program characterized by the above.
A communication system comprising a transmitting device for transmitting a signal and a receiving device for receiving the signal,
The receiving device is:
A plurality of signal detectors that extract a signal of a predetermined length from the received signal;
A decoding unit for decoding the signal of the extracted section;
A synchronization unit for detecting a plurality of timings based on different references from the received signal;
With
Each of the signal detection units determines a section for extracting a signal using one of the detected timings;
A communication system characterized by the above.
A receiving program characterized by the above.