Single-carrier MIMO transmitter and single-carrier MIMO receiver

Abstract

To improve a transmission efficiency when performing a MIMO transmission using an SC-FDE system.SOLUTION: In a pilot signal insertion part 15-1 of a transmission device 1, two continuous UWs or null data are arranged on a diagonal line against a symbol sequence of a block that is the same number of the number of transmission (A), a pilot signal group is constructed by null data (B), the number of pilot signal symbols is powers of 2 (C), the number of MIMO detection range symbols SS is powers of 2, and the following equation is satisfied: SS=(a+b)×d+c×(2×d-1) when a is the number of MIMO block number symbols, b is the number of data symbols, c is the number of pilot signal symbols, and d is the number of MIMO transmissions (D), and the pilot signal is inserted into a predetermined position so that it has a block construction that satisfies the condition that the two continuous pilot signals contained in the first block of a detection object block are the same (E).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a single-carrier MIMO (Multiple Input Multiple Output) transmitter and a single-carrier MIMO receiver that can be used in a wireless transmission system such as broadcasting or communication, and particularly relates to an improvement in transmission efficiency in a MIMO SC-FDE (Single Carrier-Frequency Domain Equalization) system that performs channel equalization in the frequency domain.

Background Art

[0002] Conventionally, in a wireless transmission system for fixed transmission such as broadcasting or communication, a single-carrier system using one carrier wave has been widely used. On the other hand, in a wireless transmission system in a mobile environment, an OFDM (Orthogonal Frequency Division Multiplexing) system using multiple carrier waves, which can follow rapid channel variations by performing channel equalization in the frequency domain on a symbol-by-symbol basis, is generally used.

[0003] Although the OFDM system is suitable for mobile transmission, compared with the single-carrier system, it generally has a large PAPR (Peak to Average Power Ratio), which is the ratio of the peak power to the average power of the transmitted signal. Therefore, it is vulnerable to non-linear distortion of the power amplifier, and it is necessary to use the operating point of the power amplifier in a region with high linearity. For this reason, in many cases, operation is performed with a large output back-off from the output level (P1dB) at the point where the gain has decreased by 1 dB with respect to the ideal linear gain, resulting in a problem of low power efficiency.

[0004] In recent years, among single-carrier systems, an SC-FDE system that performs channel equalization (a process of restoring changes in amplitude and phase generated in the propagation path) in the frequency domain has been proposed (see, for example, Non-Patent Document 1 and Patent Document 1).

[0005] In the SC-FDE method, channel estimation and channel equalization in the frequency domain are performed in units of a fixed number of consecutive symbols (block units), enabling it to follow high-speed channel variations in mobile transmission. Therefore, the SC-FDE method is more suitable for mobile transmission than the conventional single-carrier method that performs channel equalization in the time domain.

[0006] Generally, in the SC-FDE method, similar to the OFDM method, by providing a guard interval (GI), inter-block interference in a multipath environment can be prevented. A receiving device applying the SC-FDE method performs block synchronization to detect the start of a block, and extracts a unique word (UW) (a signal with a known fixed pattern in the transmitting and receiving devices), which is a pilot signal for channel estimation, and data. Then, the receiving device converts the UW and data into the frequency domain by Fourier transform to perform channel estimation and channel equalization processing. After that, the receiving device converts the data back into a time-domain signal by inverse Fourier transform and performs processing such as symbol determination.

[0007] Since this SC-FDE method generally has a smaller PAPR than the OFDM method, it is possible to reduce the output back-off of the power amplifier, enabling high-efficiency operation of the power amplifier and also enabling miniaturization of the power amplifier in mobile transmission.

[0008] Furthermore, a MIMO SC-FDE method corresponding to MIMO, which wirelessly transmits a large amount of information at high speed using multiple antennas, has been proposed (see, for example, Patent Document 2). In MIMO, a plurality of signals corresponding to the number of transmissions (multiplicity) are transmitted, and these signals are received in a state where they are mixed with each other.

[0009] Therefore, in the receiving device, MIMO detection (MIMO channel estimation and equalization in the frequency domain) is required to detect the original transmitted signal from the received signal. To distinguish a plurality of transmitted signals, an arrangement is made such that the positional relationship of the UW is different across a plurality of blocks, and a device is devised so that the transmitted signals are orthogonal between the transmission systems.

[0010] FIG. 9 is a diagram showing the symbol block configuration of the null structure of the MIMO SC-FDE system in the prior art, showing the case where the number of transmissions is 2. The transmission signal x1 indicates the signal transmitted from the first transmission system in the transmission device, and the transmission signal x2 indicates the signal transmitted from the second transmission system.

[0011] The transmission signals x1 and x2 are configured in units of two blocks: an MIMO odd block and an MIMO even block. When the number of transmissions is 2, MIMO detection is performed at the receiving device in units of these two blocks.

[0012] Each block of the transmission signals x1 and x2 is composed of two consecutive UW or null data, a GI in which the latter part of the data is inserted as a CP (Cyclic Prefix), an MIMO block number, and data.

[0013] The UW and null data are pilot signals used for channel estimation. The UW consists of a known fixed pattern between transmission and reception, and a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence with excellent periodic autocorrelation characteristics such as a Zadoff-Chu sequence with a constant amplitude in the time domain and frequency domain is used. The CP is information obtained by copying the latter part of the data and is necessary for performing the conversion between the time domain and the frequency domain.

[0014] The MIMO block number is information for identifying from where each of the multiple blocks starts in order for the receiving device to correctly perform MIMO detection. The first MIMO odd block and the second MIMO even block are identified before MIMO signal separation is performed by the MIMO block number.

[0015] For the MIMO odd blocks, a symbol sequence obtained by differentially modulating the value corresponding to 1 is set as the MIMO block number, and for the MIMO even blocks, a symbol sequence obtained by differentially modulating the value corresponding to 2 is set as the MIMO block number. As the differential modulation, a method enabling delay detection such as DBPSK (Differential Binary Phase Shift Keying) or DQPSK (Differential Quadrature Phase Shift Keying) is used.

[0016] The MIMO block number is generated using the differential modulation method described above and is arranged within the symbol sequence to be equalized. Thereby, the identification accuracy of the positional relationship of the UW and the transmission efficiency can be improved (see, for example, Patent Document 3).

[0017] As shown in FIG. 9, in two consecutive blocks, it is arranged such that the presence or absence (null data) of two consecutive UWs is set alternately in two transmission systems.

[0018] Thereby, in the MIMO SC-FDE system, the transmission rate can be improved as compared with the SISO (Single Input Single Output) (SISO SC-FDE system) using the SC-FDE system of Patent Document 1 described above.

Prior Art Documents

Patent Documents

[0019]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0020]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0021] However, in the MIMO SC-FDE system of Patent Document 2 described above, a CP is individually added to the signal to be equalized, whereas in the SISO SC-FDE system of Patent Document 1 described above, since the UW also serves as the CP, the CP is not individually added.

[0022] Therefore, the MIMO SC-FDE system has a lower data ratio (data efficiency) with respect to the transmission signal than the SISO SC-FDE system. In the MIMO SC-FDE system, it has been desired to improve the transmission efficiency.

[0023] Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a single-carrier MIMO transmitter and a single-carrier MIMO receiver capable of improving the transmission efficiency when performing MIMO transmission using the SC-FDE system.

Means for Solving the Problems

[0024] To solve the above problems, the single-carrier MIMO transmission apparatus according to claim 1 includes a plurality of transmission antennas, and for each of a plurality of transmission systems corresponding to the plurality of transmission antennas, generates a block of the MIMO SC-FDE method, and transmits a modulated wave of the block for each transmission system via the transmission antenna. In the single-carrier MIMO transmission apparatus, an inter-system allocation unit that allocates to the plurality of transmission systems a coded bit sequence of data to be transmitted, a mapping unit for each transmission system that performs mapping on the coded bit sequence of the data to be transmitted allocated by the inter-system allocation unit by a predetermined modulation method and outputs a bit sequence after mapping, a MIMO block number insertion unit for each transmission system that inserts a MIMO block number at a predetermined position in the bit sequence after mapping output by the mapping unit and outputs a symbol sequence in which the MIMO block number is inserted, a pilot signal insertion unit for each transmission system that inserts two consecutive pilot signals at a predetermined position in the symbol sequence in which the MIMO block number is inserted output by the MIMO block number insertion unit and generates a symbol sequence of a detection target block composed of the same number of the blocks as the number of transmission systems with the block composed of the two consecutive pilot signals, the MIMO block number, and the data to be transmitted as a unit, where the number of symbols of the MIMO block number is set as a MIMO block number symbol number a, the number of symbols of the data to be transmitted is set as a data symbol number b, the number of symbols of the pilot signal is set as a pilot signal symbol number c, the number of the plurality of transmission antennas is set as a MIMO transmission number d, the number of symbols of a MIMO detection range where equalization is performed in the frequency domain is set as a MIMO detection range symbol number SS, the MIMO detection range is set as a range from the MIMO block number included in the first block in the detection target block to the leading pilot signal included in the first block in the next detection target block of the detection target block, when the pilot signal insertion unit configures a matrix with the two consecutive pilot signals included in the detection target block in the plurality of transmission systems as one element,Two consecutive UW (Unique Word) elements consisting of signals of a known fixed pattern are arranged on the diagonal of the matrix (A), among all the pilot signals constituting the matrix, the pilot signals other than the two consecutive UW arranged on the diagonal are null data (B), the number of pilot signal symbols c is a power of 2 (C), the MIMO detection range symbol number SS is a power of 2 and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). The two consecutive pilot signals are inserted at a predetermined position so as to satisfy each condition, and a symbol sequence of the detection target block is generated.

[0025] Further, the single-carrier MIMO transmission apparatus according to claim 2 includes a plurality of transmission antennas, and for each of a plurality of transmission systems corresponding to the plurality of transmission antennas, generates a block of the MIMO SC-FDE system, and transmits the modulated wave of the block for each transmission system via the transmission antenna. In the single-carrier MIMO transmission apparatus, an inter-system allocation unit that allocates to the plurality of transmission systems the coded bit sequence of the data to be transmitted, a mapping unit for each transmission system that performs mapping on the coded bit sequence of the data to be transmitted allocated by the inter-system allocation unit by a predetermined modulation method and outputs the bit sequence after mapping, a MIMO block number insertion unit for each transmission system that inserts a MIMO block number at a predetermined position in the bit sequence after mapping output by the mapping unit and outputs a symbol sequence in which the MIMO block number is inserted, and a pilot signal insertion unit for each transmission system that inserts two consecutive pilot signals at a predetermined position in the symbol sequence in which the MIMO block number is inserted output by the MIMO block number insertion unit and generates a symbol sequence of a detection target block composed of the same number of the blocks as the number of transmission systems with the block composed of the two consecutive pilot signals, the MIMO block number, and the data to be transmitted as a unit. Let the symbol number of the MIMO block number be a, the symbol number of the data to be transmitted be b, the symbol number of the pilot signal be c, the number of the plurality of transmission antennas be d, the symbol number of the MIMO detection range where equalization is performed in the frequency domain be SS, and the MIMO detection range be set as the range from the MIMO block number included in the first block in the detection target block to the leading pilot signal included in the first block in the next detection target block of the detection target block. When the pilot signal insertion unit configures a matrix with the two consecutive pilot signals included in the detection target block in the plurality of transmission systems as one element, null data elements are arranged on the diagonal of the matrix (A).Of all the pilot signals constituting the matrix, the pilot signals other than the null data arranged on the diagonal are two consecutive UW (Unique Word) signals consisting of known fixed pattern signals (B), the number of pilot signal symbols c is a power of 2 (C), the number of MIMO detection range symbols SS is a power of 2 and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). The two consecutive pilot signals are inserted at a predetermined position so as to satisfy each condition, and a symbol sequence of the detection target block is generated.

[0026] Furthermore, the single-carrier MIMO receiver according to claim 3 includes one or more receiving antennas, receives modulated waves transmitted from a plurality of transmitting antennas provided in a single-carrier MIMO transmitter via the one or more receiving antennas in corresponding one or more receiving systems, estimates a MIMO channel based on received pilot signals included in a received signal in which blocks of the MIMO SC-FDE system are multiplexed, and performs equalization in the frequency domain. In the single-carrier MIMO receiver, the block is composed of two consecutive pilot signals, a MIMO block number, and data. Let the number of symbols of the MIMO block number be a MIMO block number symbol number a, the number of symbols of the data be a data symbol number b, the number of symbols of the pilot signal be a pilot signal symbol number c, the number of the plurality of transmitting antennas be a MIMO transmission number d, and the number of symbols in a MIMO detection range where equalization is performed in the frequency domain be a MIMO detection range symbol number SS. Assume that a detection target block is composed of the same number of the blocks as the MIMO transmission number d. Let the MIMO detection range be a range from the MIMO block number included in the first block in the detection target block to the leading pilot signal included in the first block in the next detection target block of the detection target block. When a matrix is configured with the two consecutive pilot signals included in the detection target block in a plurality of transmitting systems of the single-carrier MIMO transmitter as one element, two consecutive UW (unique word) elements composed of signals of a known fixed pattern are arranged on the diagonal of the matrix (A), among all the pilot signals constituting the matrix, the pilot signals other than the two consecutive UW arranged on the diagonal are null data (B), the pilot signal symbol number c is a power of 2 (C), the MIMO detection range symbol number SS is a power of 2, and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). Then, perform fast Fourier transform on the pilot signal to estimate the MIMO channel.For each receiving system, perform upsampling of the MIMO channel so as to match the number of symbols SS of the preset MIMO detection range symbol, and output the upsampled MIMO channel; perform fast Fourier transform on the MIMO detection range corresponding to the preset number of symbols SS of the MIMO detection range, and output a signal in the frequency domain; input the upsampled MIMO channel output by the MIMO channel estimation unit for each receiving system and the signal in the frequency domain output by the Fourier transform unit for each receiving system, and perform MIMO channel equalization in the frequency domain using the upsampled MIMO channel and the signal in the frequency domain corresponding to the preset number of symbols SS of the MIMO detection range. The MIMO channel estimation unit extracts the received pilot signals included in the same number of blocks as the MIMO transmission number d constituting the detection target block from the signals received by the receiving system, performs fast Fourier transform on the received pilot signals, and divides the fast Fourier transform result of the received pilot signals by the fast Fourier transform result of the UW in the time domain to estimate the channel response between each of the plurality of transmitting antennas and the receiving antenna of the receiving system.

[0027] Further, the single-carrier MIMO receiving apparatus according to claim 4 includes one or more receiving antennas, receives modulated waves transmitted from a plurality of transmitting antennas provided in a single-carrier MIMO transmitting apparatus via the one or more receiving antennas in corresponding one or more receiving systems, estimates a MIMO channel based on a received pilot signal included in a received signal in which blocks of the MIMO SC-FDE system are multiplexed, and performs equalization in the frequency domain. In the single-carrier MIMO receiving apparatus, the block is composed of two consecutive pilot signals, a MIMO block number, and data. Let the number of symbols of the MIMO block number be a MIMO block number symbol number a, the number of symbols of the data be a data symbol number b, the number of symbols of the pilot signal be a pilot signal symbol number c, the number of the plurality of transmitting antennas be a MIMO transmission number d, and the number of symbols in a MIMO detection range where equalization is performed in the frequency domain be a MIMO detection range symbol number SS. It is assumed that a detection target block is composed of the same number of the blocks as the MIMO transmission number d. The MIMO detection range is defined as a range from the MIMO block number included in the first block of the detection target block to the leading pilot signal included in the first block of the next detection target block of the detection target block. When a matrix is configured with the two consecutive pilot signals included in the detection target block in a plurality of transmitting systems of the single-carrier MIMO transmitting apparatus as one element, elements of null data are arranged on the diagonal line of the matrix (A). Among all the pilot signals constituting the matrix, the pilot signals other than the null data arranged on the diagonal line are two consecutive UW (Unique Word) consisting of signals of a known fixed pattern (B). The pilot signal symbol number c is a power of 2 (C). The MIMO detection range symbol number SS is a power of 2 and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D). And the two consecutive pilot signals included in the first block of the detection target block are the same (E). The pilot signal is subjected to fast Fourier transform to estimate the MIMO channel.For each receiving system, an MIMO channel estimator that upsamples the MIMO channel so as to match the number of symbols SS of the preset MIMO detection range symbol and outputs the upsampled MIMO channel; a Fourier transform unit for each receiving system that performs a fast Fourier transform on the MIMO detection range corresponding to the preset number of symbols SS of the MIMO detection range and outputs a signal in the frequency domain; and the upsampled MIMO channel output by the MIMO channel estimator for each receiving system, and the signal in the frequency domain output by the Fourier transform unit for each receiving system are respectively input, and MIMO channel equalization is performed in the frequency domain using the upsampled MIMO channel and the signal in the frequency domain corresponding to the preset number of symbols SS of the MIMO detection range, a frequency domain MIMO channel equalization unit, wherein the MIMO channel estimator extracts the received pilot signals included in the same number of blocks as the MIMO transmission number d constituting the detection target block from the signals received by the receiving system, performs a fast Fourier transform on each of the same number of received pilot signals as the MIMO transmission number d, and based on the fast Fourier transform results of these received pilot signals and the fast Fourier transform result of the UW in the time domain, estimates the channel response between each of the plurality of transmitting antennas and the receiving antenna of the receiving system.

Advantages of the Invention

[0028] As described above, according to the present invention, when performing MIMO transmission using the SC-FDE method, the transmission efficiency can be improved.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0030] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The single-carrier MIMO transmitter of the present invention performs MIMO demultiplexing on the coded bit sequence of data to be transmitted, and configures a symbol block of the MIMO SC-FDE system so as to satisfy the following conditions (A), (B), (C), (D), and (E), such as UW or null data, which are pilot signals, being arranged on the diagonal in the block configuration of a plurality of transmission signals.

[0031] Further, the single-carrier MIMO receiver of the present invention estimates the MIMO channel by using the fact that UW or null data, which are pilot signals included in the received signal, satisfy the following conditions (A), (B), (C), (D), and (E) such as being arranged on the diagonal in the block configuration of a plurality of transmission signals, and performs MIMO detection on the MIMO detection range that satisfies the condition (D) described below.

[0032] As a result, in the transmitted signal, the UW can be used as the CP, and it is not necessary to insert the latter part of the data as the CP. Therefore, transmission by the MIMO SC-FDE method becomes possible without individually adding the CP, and the data efficiency can be improved compared to the prior art. Accordingly, when performing MIMO transmission using the SC-FDE method, the transmission efficiency can be improved.

[0033] Also, since the power of the pilot signal does not deviate between the transmitted signals, on the receiving side, it is possible to estimate a MIMO channel with no deviation in accuracy between the transmitted signals.

[0034] Hereinafter, an example of a 2-transmit and 2-receive MIMO SC-FDE method with the number of transmissions and the number of receptions both being 2 will be given to describe an embodiment of the present invention. However, it is possible to increase the number of transmissions and the number of receptions, and it is also possible to set the number of receptions to 1.

[0035] 〔Single-carrier MIMO transmission device〕 First, a single-carrier MIMO transmission device according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a schematic configuration of the single-carrier MIMO transmission device according to the embodiment of the present invention.

[0036] This transmission device (single-carrier MIMO transmission device) 1 is configured as a single-carrier transmission device that generates a signal capable of MIMO detection in the frequency domain by a receiving device shown in FIG. 5 described later, and wirelessly transmits information using a plurality of antennas (transmission antennas 20-1, 20-2).

[0037] This transmission device 1 includes a pre - transmission processing unit 10, an inter - system distribution unit 11, inner interleaving units 12 - 1 and 12 - 2, mapping units 13 - 1 and 13 - 2, MIMO block number insertion units 14 - 1 and 14 - 2, pilot signal insertion units 15 - 1 and 15 - 2, band - limiting filter units 16 - 1 and 16 - 2, digital quadrature modulation units 17 - 1 and 17 - 2, DA conversion units 18 - 1 and 18 - 2, transmission high - frequency units 19 - 1 and 19 - 2, and transmission antennas 20 - 1 and 20 - 2.

[0038] The pre - transmission processing unit 10 performs pre - processing such as energy spreading processing, error - correction coding processing, and interleaving processing on the information bit sequence (data to be transmitted) to be transmitted, generates a coded bit sequence, and outputs the coded bit sequence to the inter - system distribution unit 11. This pre - processing can apply arbitrary energy spreading processing, error - correction coding processing, interleaving processing, etc.

[0039] The inter - system distribution unit 11 inputs the coded bit sequence from the pre - transmission processing unit 10, distributes the bits of the coded bit sequence to two transmission systems, and outputs the coded bit sequence after bit distribution to the inner interleaving units 12 - 1 and 12 - 2. This bit distribution is performed according to the number of transmissions, and can be distributed in an arbitrary pattern as long as it corresponds to the reverse distribution on the receiving side.

[0040] Hereinafter, the inner interleaving unit 12 - 1, mapping unit 13 - 1, MIMO block number insertion unit 14 - 1, pilot signal insertion unit 15 - 1, band - limiting filter unit 16 - 1, digital quadrature modulation unit 17 - 1, DA conversion unit 18 - 1, transmission high - frequency unit 19 - 1, and transmission antenna 20 - 1 of the first transmission system will be described. The same applies to the inner interleaving unit 12 - 2, mapping unit 13 - 2, MIMO block number insertion unit 14 - 2, pilot signal insertion unit 15 - 2, band - limiting filter unit 16 - 2, digital quadrature modulation unit 17 - 2, DA conversion unit 18 - 2, transmission high - frequency unit 19 - 2, and transmission antenna 20 - 2 of the second transmission system.

[0041] The inner interleaving unit 12-1 receives the coded bit sequence after bit allocation from the inter-system allocation unit 11, and performs inner interleaving processing such as bit interleaving and time interleaving on the coded bit sequence after bit allocation. Then, the inner interleaving unit 12-1 outputs the coded bit sequence after inner interleaving to the mapping unit 13-1.

[0042] The mapping unit 13-1 receives the coded bit sequence after inner interleaving from the inner interleaving unit 12-1, and performs mapping on the coded bit sequence after inner interleaving processing by a predetermined modulation method such as QPSK, 16QAM, 16APSK, etc. Then, the mapping unit 13-1 outputs the bit sequence after mapping to the MIMO block number insertion unit 14-1.

[0043] The MIMO block number insertion unit 14-1 receives the bit sequence after mapping from the mapping unit 13-1, and inserts the MIMO block number (MIMO block number symbol) at a predetermined position in the bit sequence after mapping. Then, the MIMO block number insertion unit 14-1 outputs the symbol sequence with the MIMO block number inserted to the pilot signal insertion unit 15-1.

[0044] Here, the MIMO block number insertion unit 14-1 generates a value for identifying the MIMO block number as a MIMO block number symbol in the modulation process in order to arrange a value for identifying the MIMO block number for the bit sequence after mapping. Specifically, the MIMO block number insertion unit 14-1 modulates the value for identifying the MIMO block number by a differential modulation method such as DBPSK or DQPSK to generate a MIMO block number symbol.

[0045] As an example of the MIMO block number, when the number of transmissions is 2, it is 0, 1. Also, when the number of transmissions is 4, it is 00, 01, 10, 11. Note that the MIMO block number insertion unit 14-1 may perform error correction coding or coding that enables error detection on the MIMO block number.

[0046] The pilot signal insertion unit 15-1 receives the symbol sequence with the MIMO block number inserted from the MIMO block number insertion unit 14-1. Then, the pilot signal insertion unit 15-1 inserts two consecutive pilot signals at predetermined positions with respect to the symbol sequence with the MIMO block number inserted. Specifically, the pilot signal insertion unit 15-1 inserts a predetermined pilot signal composed of UW and null data at a predetermined position so that the block configuration is such that two consecutive UWs are arranged diagonally or the null data is arranged diagonally, with the transmission signals (symbol sequences) of the same number of blocks as the number of transmissions as a unit.

[0047] For example, in the example of FIG. 2 described later, the pilot signal insertion unit 15-1 inserts the pilot signal of UW and null data at a predetermined position so that the block configuration is such that two consecutive UWs are arranged diagonally in the transmission signals x1 and x2 of the same number of blocks as the number of transmissions 2. In this case, in the transmission signals x1 and x2 of the same number of blocks as the number of transmissions 2, the block configuration in which two consecutive UWs are arranged diagonally is also the block configuration in which the null data is arranged diagonally.

[0048] The pilot signal insertion unit 15-1 generates the symbol sequence with two consecutive pilot signals inserted as the symbol sequence of the MIMO SC-FDE block and outputs this to the band-limiting filter unit 16-1.

[0049] Here, the predetermined pilot signal is a pilot signal set in advance so as to satisfy the following conditions (A) to (E). (A) In the block configuration of the transmission signal consisting of the same number of blocks as the number of transmissions, two consecutive UWs or null data are arranged diagonally (UW diagonal structure or null data diagonal structure). This condition of (A) means that when a matrix is constructed with two consecutive pilot signals included in the detection target blocks (refer to α in FIGS. 2, 3, and 4 described later) in the plurality of transmission systems provided in the transmission device 1 as one element, two consecutive UW elements or null data elements are arranged on the diagonal of the matrix. For example, in the example of FIG. 3, the two consecutive UW elements arranged on the diagonal of the matrix refer to the elements in the first row and first column, second row and second column, third row and third column, and fourth row and fourth column of the matrix.

[0050] (B) The plurality of pilot signals included in the block configuration of the transmission signal consisting of the same number of blocks as the number of transmissions are composed of UW and null data. When UW is arranged diagonally under the condition of (A) described above, the other pilot signals are null data. When null data is arranged diagonally, the other pilot signals are UW.

[0051] (C) The number of symbols of the pilot signal (pilot signal symbol number c) is a power of 2. (D) The number of symbols (MIMO detection range symbol number, number of symbols to be equalized) SS of the MIMO detection range in which MIMO channel equalization is performed in the frequency domain is a power of 2 and is expressed by the following formula. [Equation 1] SS = (a + b) × d + c × (2 × d - 1) ···(1) Let a be the number of symbols of the MIMO block number, b be the number of data symbols, c be the number of symbols of the pilot signal, and d be the number of transmissions (MIMO transmission number, number of transmission antennas, number of transmission systems).

[0052] Here, the MIMO SC-FDE block is composed of two consecutive pilot signal sequences, the MIMO block number symbol sequence, and the data symbol sequence. The block to be detected (refer to α in FIGS. 2, 3, and 4 described later) is composed of the same number of MIMO SC-FDE blocks as the number of transmissions d. That is, the pilot signal insertion unit 15-1 generates a block to be detected in units of MIMO SC-FDE blocks.

[0053] The MIMO detection range is the range from the MIMO block number included in the first block in the block to be detected to the first pilot signal included in the first block in the next block to be detected of the block to be detected. That is, the MIMO detection range is the MIMO block number symbol sequence, the data symbol sequence, the pilot signal sequence, the pilot signal sequence, the MIMO block number symbol sequence, the data symbol sequence, ···, the MIMO block number symbol sequence, the data symbol sequence, and the pilot signal sequence.

[0054] (E) The two consecutive pilot signals included in the first block in the block to be detected are the same. For example, in FIGS. 2, 3, and 4 described later, the first block includes two consecutive UWs.

[0055] In this way, by satisfying the above conditions (A) and (B), the UW or null data can be evenly arranged among the transmission signals. As a result, the power of the pilot signals is equal among the transmission signals and does not deviate among the transmission signals. Therefore, on the receiving side, a MIMO channel with no bias in accuracy can be estimated among the transmission signals, and equal receiving performance can be obtained among the transmission signals.

[0056] Also, by satisfying the above condition (C), the pilot signals can be made the subject of fast Fourier transform, and on the receiving side, the MIMO channel can be estimated.

[0057] Also, by satisfying the condition of (D) described above, the signals within the MIMO detection range can be made the targets of fast Fourier transform and inverse fast Fourier transform, and at the receiving side, MIMO channel equalization can be performed and data can be decoded.

[0058] Furthermore, by satisfying the condition of (E) described above, since the latter (second) UW among the two consecutive UWs in the first block also serves as a CP, there is no need to insert a CP into the block. As a result, the transmission efficiency can be improved and, since there is no need to handle the CP, the processing load can be reduced.

[0059] FIG. 2 is a diagram showing an example of a symbol block configuration of the MIMO SC-FDE system when the number of transmissions is 2 in an embodiment of the present invention. The transmission signals x1 and x2 indicate the respective signals transmitted from the first and second transmission systems in the transmission device 1.

[0060] The pilot signals are UW and null data. The UW is a signal of a known fixed pattern between transmission and reception, and a CAZAC sequence or the like having excellent periodic autocorrelation characteristics such as a Zadoff-Chu sequence with a constant amplitude in the time domain and the frequency domain is used as described with reference to FIG. 9.

[0061] The transmission signals x1 and x2 are configured in units of two blocks, namely the first block which is a MIMO odd block and the second block which is a MIMO even block. These two blocks constitute a detection target block α, and MIMO detection is performed at the receiving side in units of this block α.

[0062] The first block of the transmission signal x1 is composed of two consecutive UWs, a MIMO block number, and data (DATA1 t0 ). The first block of the transmission signal x2 is composed of null data having the same number of symbols as two consecutive UWs, a MIMO block number, and data (DATA2 t0 ).

[0063] The second block of the transmission signal x1 consists of null data having the same number of symbols as two consecutive UWs, the MIMO block number, and data (DATA1 t1 )). The second block of the transmission signal x2 consists of two consecutive UWs, the MIMO block number, and data (DATA2 t1 ).

[0064] For the transmission signal x1, the latter (second) UW among the two consecutive UWs in the first block included in the detection target block α is the same as the former (first) UW among the two consecutive UWs in the first block included in the next detection target block, and also serves as the CP in the MIMO detection range. That is, for the transmission signal x1, the first block includes two consecutive UWs, and it can be said that the latter UW among the two consecutive UWs is the GI in which the latter part of the MIMO detection range is inserted as the CP.

[0065] The transmission signal x2 has the same configuration as when the transmission signal x1 is shifted by one block. Therefore, for the transmission signal x2 as well, it can be said that the latter UW among the two consecutive UWs is the GI inserted as the CP.

[0066] As a result, since it is not necessary to insert the latter part of the MIMO detection range as the CP, the transmission efficiency can be improved and the processing load can be reduced.

[0067] In FIG. 2, from the above-mentioned conditions (C) and (D), the number of transmissions d = 2, the number of symbols of the MIMO block number a = 2, and the number of symbols of the pilot signal c = 2 8 = 256, then the number of data symbols b = 1662, and the MIMO detection range is 2 12 = 4096.

[0068] The number c of pilot signal symbols is actually the number of symbols corresponding to the GI length in the OFDM system, which is set according to the maximum delay time at which the multipath arrives. The symbol length of the pilot signal is determined from the number of symbols and the symbol rate, and is set so as not to exceed the maximum delay time.

[0069] As described above, as shown in FIG. 2, the pilot signal insertion unit 15-1 inserts pilot signals of UW and null data at the positions shown in FIG. 2 so that the block configuration is such that two consecutive UWs are arranged diagonally in the transmission signals x1 and x2 of the same number of blocks as the transmission number 2.

[0070] FIG. 3 is a diagram showing an example of a symbol block configuration (an example of UW diagonal structure) of the MIMO SC-FDE system when the number of transmissions is 4 in the embodiment of the present invention, showing an example in which two consecutive UWs are arranged diagonally. The transmission signals x1, x2, x3, and x4 represent the respective signals transmitted from the first, second, third, and fourth transmission systems in the transmission device 1. The pilot signals are UW and null data.

[0071] The transmission signals x1, x2, x3, and x4 are configured in units of four blocks from the first to the fourth. The four blocks constitute a detection target block α, and MIMO detection is performed on the reception side in units of this block α.

[0072] The first block of the transmission signal x1 is composed of two consecutive UWs, a MIMO block number, and data (DATA1 t0 ). The first blocks of the transmission signals x2, x3, and x4 are composed of null data having the same number of symbols as two consecutive UWs, a MIMO block number, and data (DATA2 t0 , DATA3 t0 , DATA4 t0 ).

[0073] The second block of the transmission signal x2 is composed of two consecutive UWs, a MIMO block number, and data (DATA2t1 ) is composed of. The second block of the transmission signals x1, x3, x4 is null data with the same number of symbols as two consecutive UW, the MIMO block number, and data (DATA1 t1 , DATA3 t1 , DATA4 t1 ).

[0074] The third block of the transmission signal x3 is composed of two consecutive UW, the MIMO block number, and data (DATA3 t2 ). The third block of the transmission signals x1, x2, x4 is null data with the same number of symbols as two consecutive UW, the MIMO block number, and data (DATA1 t2 , DATA2 t2 , DATA4 t2 ).

[0075] The fourth block of the transmission signal x4 is composed of two consecutive UW, the MIMO block number, and data (DATA4 t3 ). The fourth block of the transmission signals x1, x2, x3 is null data with the same number of symbols as two consecutive UW, the MIMO block number, and data (DATA1 t3 , DATA2 t3 , DATA3 t3 ).

[0076] For the transmission signal x1, the latter (second) UW of the two consecutive UW in the first block included in the detection target block α is the same as the first (first) UW of the two consecutive UW in the first block included in the next detection target block, and also serves as the CP in the MIMO detection range. That is, for the transmission signal x1, the first block includes two consecutive UW, and the latter UW of the two consecutive UW can be said to be the GI in which the latter part of the MIMO detection range is inserted as the CP.

[0077] The transmission signal x2 has the same configuration as when the transmission signal x1 is shifted by one block. The transmission signal x3 has the same configuration as when the transmission signal x2 is shifted by one block. The transmission signal x4 has the same configuration as when the transmission signal x3 is shifted by one block. Therefore, also for the transmission signal x2, it can be said that the latter UW of the two consecutive UWs in the second block is the GI inserted as the CP. The same applies to the third block of the transmission signal x3 and the fourth block of the transmission signal x4.

[0078] As a result, since it is not necessary to insert the latter part of the MIMO detection range as the CP, the transmission efficiency can be improved and the processing load can be reduced.

[0079] In FIG. 3, from the above-mentioned conditions (C) and (D), the number of transmissions d = 4, the number of symbols a = 2 in the MIMO block number, and the number of pilot signal symbols c = 2 8 = 256, then the number of data symbols b = 1598, and the MIMO detection range is 2 13 = 8192.

[0080] Thus, as shown in FIG. 3, the pilot signal insertion unit 15-1 inserts the pilot signals of the UW and the null data at the positions shown in FIG. 3 so that the block configuration is such that two consecutive UWs are arranged diagonally in the transmission signals x1, x2, x3, x4 of the same number of blocks as the number of transmissions 4.

[0081] FIG. 4 is a diagram showing an example of a symbol block configuration (example of a null data diagonal structure) of the MIMO SC-FDE method when the number of transmissions is 4 in the embodiment of the present invention, and shows an example in which null data is arranged diagonally. This example of the symbol block configuration uses null data of the same number of symbols instead of the two consecutive UWs shown in FIG. 3.

[0082] Similar to FIG. 3, the transmission signals x1, x2, x3, and x4 are each composed of four blocks numbered from the first to the fourth. These four blocks constitute the block α to be detected, and MIMO detection is performed on the receiving side using this block as a unit.

[0083] The first block of the transmission signals x1, x2, and x3 consists of two consecutive UWs, the MIMO block number, and data (DATA1 t0 , DATA2 t0 , DATA3 t0 ). The first block of the transmission signal x4 consists of null data with the same number of symbols as two consecutive UWs, the MIMO block number, and data (DATA4 t0 ).

[0084] The second block of the transmission signals x1, x2, and x4 consists of two consecutive UWs, the MIMO block number, and data (DATA1 t1 , DATA2 t1 , DATA4 t1 ). The second block of the transmission signal x3 consists of null data with the same number of symbols as two consecutive UWs, the MIMO block number, and data (DATA3 t1 ).

[0085] The third block of the transmission signals x1, x3, and x4 consists of two consecutive UWs, the MIMO block number, and data (DATA1 t2 , DATA3 t2 , DATA4 t2 ). The third block of the transmission signal x2 consists of null data with the same number of symbols as two consecutive UWs, the MIMO block number, and data (DATA2 t2 ).

[0086] The fourth block of the transmission signals x2, x3, and x4 consists of two consecutive UWs, the MIMO block number, and data (DATA2 t3 , DATA3 t3 , DATA4 t3) It is composed by. The fourth block of the transmission signal x1 is null data with the same number of symbols as two consecutive UW, MIMO block number, and data (DATA1 t3 ) It is composed by.

[0087] For the transmission signals x1, x2, and x3, among the two consecutive UW in the first block included in the detection target block α, the latter (second) UW is the same as the first (first) UW among the two consecutive UW in the first block included in the next detection target block, and it also serves as the CP in the MIMO detection range. That is, for the transmission signals x1, x2, and x3, the first block includes two consecutive UW, and the latter UW among the two consecutive UW can be said to be the GI inserted as the CP in the latter part of the MIMO detection range.

[0088] The transmission signal x2 has the same configuration as when the transmission signal x1 is shifted by one block, the transmission signal x3 has the same configuration as when the transmission signal x2 is shifted by one block, and the transmission signal x4 has the same configuration as when the transmission signal x3 is shifted by one block. Therefore, for the second blocks of the transmission signals x1, x2, and x4, it can also be said that the latter UW among the two consecutive UW is the GI inserted as the CP. The same applies to the third blocks of the transmission signals x1, x3, and x4 and the fourth blocks of the transmission signals x2, x3, and x4.

[0089] As a result, since it is not necessary to insert the latter part of the MIMO detection range as the CP, the transmission efficiency can be improved and the processing load can be reduced.

[0090] In FIG. 4, from the above-mentioned conditions (C) and (D), the number of transmissions d = 4, the number of symbols of the MIMO block number a = 2, and the number of pilot signal symbols c = 2 8 = 256, then the number of data symbols b = 1598, and the MIMO detection range is 2 13 = 8192.

[0091] In this way, as shown in FIG. 4, the pilot signal insertion unit 15-1 arranges null data with the same number of symbols as two consecutive UW in the transmission signals x1, x2, x3, x4 of the same number of blocks as the transmission number 4 in a block configuration where the null data is arranged diagonally, and inserts the pilot signals of UW and null data at the positions shown in FIG. 4.

[0092] Also, as shown in FIGS. 3 and 4, the power of the pilot signal is equal among the transmission signals and does not deviate among the transmission signals.

[0093] Returning to FIG. 1, the band-limiting filter unit 16-1 inputs the symbol sequence of the MIMO SC-FDE block from the pilot signal insertion unit 15-1. Then, the band-limiting filter unit 16-1 performs 2-fold upsampling on the symbol sequence of the MIMO SC-FDE block and performs waveform shaping by band-limiting filter processing. The band-limiting filter unit 16-1 outputs the symbol sequence of the MIMO SC-FDE block after waveform shaping to the digital quadrature modulation unit 17-1. Generally, a root raised cosine filter is used as the band-limiting filter.

[0094] The digital quadrature modulation unit 17-1 inputs the symbol sequence of the MIMO SC-FDE block after waveform shaping from the band-limiting filter unit 16-1. Then, the digital quadrature modulation unit 17-1 performs digital quadrature modulation processing on the symbol sequence of the MIMO SC-FDE block after waveform shaping.

[0095] Also, the digital quadrature modulation unit 17-1 performs aperture correction to correct the aperture effect due to digital / analog conversion in the DA conversion unit 18-1. The digital quadrature modulation unit 17-1 outputs the signal after quadrature modulation to the DA conversion unit 18-1.

[0096] The DA conversion unit 18-1 inputs the signal after quadrature modulation from the digital quadrature modulation unit 17-1, converts the digital signal, which is the signal after quadrature modulation, into an analog signal, and outputs the analog signal to the transmission high-frequency unit 19-1.

[0097] The transmission high-frequency section 19-1 receives an analog signal from the DA conversion section 18-1, converts the frequency of the analog signal into a radio frequency, amplifies it with a power amplifier so as to obtain a specified power, and transmits a modulated wave from the transmission antenna 20-1.

[0098] As described above, according to the transmission apparatus 1 of the embodiment of the present invention, the pilot signal insertion section 15-1 forms a block configuration in which two consecutive UW are arranged diagonally or a block configuration in which null data is arranged diagonally, with the transmission signals of the same number of blocks as the number of transmissions as a unit for the symbol sequence, and generates an MIMO SC-FDE block by inserting two consecutive pilot signals so as to satisfy the above-described conditions (A), (B), (C), (D), and (E).

[0099] Then, from the transmission apparatus 1, a modulated wave including a pilot signal satisfying the above-described conditions (A), (B), (C), (D), and (E), that is, a pilot signal of two consecutive UW or null data arranged diagonally in the transmission signals of the same number of blocks as the number of transmissions is transmitted.

[0100] FIG. 8 is a diagram for comparing symbol block configuration examples in the prior art and the embodiment of the present invention. FIG. 8(1) is a symbol block configuration example when the number of transmissions is 2 in the prior art, and FIG. 8(2) shows a symbol block configuration example when the number of transmissions is 2 in the embodiment of the present invention.

[0101] From FIGS. 8(1) and 8(2), it can be seen that in the prior art, a CP is inserted into the MIMO SC-FDE block, whereas in the embodiment of the present invention, the UW also serves as the CP and no CP is inserted into the MIMO SC-FDE block.

[0102] Thus, in the embodiment of the present invention, since the latter (second) UW of the two consecutive UW in the first block also serves as the CP, there is no need to individually insert the CP into the MIMO SC-FDE block.

[0103] That is, in each transmission system, since it is not necessary to insert CP, the transmission efficiency can be improved and the processing load can be reduced.

[0104] Therefore, when performing MIMO transmission using the SC-FDE method, the ratio of valid data increases with respect to all transmission signals. Therefore, when compared at the same symbol rate, the transmission rate can be made higher than that of the prior art, and the transmission efficiency can be improved.

[0105] Also, the pilot signal is composed of UW and null data. In the examples shown in FIGS. 2 and 3, two consecutive UWs are arranged diagonally, and the other pilot signals are null data. Also, in the example shown in FIG. 4, null data is arranged diagonally, and the other pilot signals are UW.

[0106] As a result, the power of the pilot signal does not deviate between the transmission signals. Therefore, on the receiving side, an MIMO channel with no deviation in accuracy between the transmission signals can be estimated, and equal reception performance can be obtained between the transmission signals.

[0107] 〔Single-Carrier MIMO Receiver〕 Next, a single-carrier MIMO receiver according to an embodiment of the present invention will be described. FIG. 5 is a block diagram showing a schematic configuration of the single-carrier MIMO receiver according to the embodiment of the present invention.

[0108] This receiver (single-carrier MIMO receiver) 2 receives modulated waves transmitted from a plurality of transmission antennas 20-1 and 20-2 of the transmission device 1 shown in FIG. 1 by a plurality of antennas (reception antennas 30-1 and 30-2), and performs MIMO detection (MIMO channel estimation and equalization in the frequency domain).

[0109] The receiving device 2 includes receiving antennas 30-1 and 30-2, receiving processing units 40-1 and 40-2, MIMO block number detection units 41-1 and 41-2, MIMO block number comparison units 42-1 and 42-2, noise power detection units 43-1 and 43-2, MIMO channel estimation units 44-1 and 44-2, Fourier transform units 45-1 and 45-2, frequency domain MIMO channel equalization unit 46, inverse Fourier transform units 47-1 and 47-2, symbol determination / likelihood calculation units 48-1 and 48-2, equalized MIMO block number decoding units 49-1 and 49-2, equalized MIMO block number determination unit 50, inner deinterleaving units 51-1 and 51-2, and a decoding unit 52.

[0110] Hereinafter, the receiving antenna 30-1, receiving processing unit 40-1, MIMO block number detection unit 41-1, MIMO block number comparison unit 42-1, noise power detection unit 43-1, MIMO channel estimation unit 44-1, Fourier transform unit 45-1, inverse Fourier transform unit 47-1, symbol determination / likelihood calculation unit 48-1, equalized MIMO block number decoding unit 49-1, and inner deinterleaving unit 51-1 of the first receiving system will be described. However, the same applies to the receiving antenna 30-2, receiving processing unit 40-2, MIMO block number detection unit 41-2, MIMO block number comparison unit 42-2, noise power detection unit 43-2, MIMO channel estimation unit 44-2, Fourier transform unit 45-2, inverse Fourier transform unit 47-2, symbol determination / likelihood calculation unit 48-2, equalized MIMO block number decoding unit 49-2, and inner deinterleaving unit 51-2 of the second receiving system.

[0111] FIG. 6 is a block diagram showing a schematic configuration of the receiving processing unit 40-1. This receiving processing unit 40-1 includes a receiving high-frequency unit 60, an AD conversion unit 61, a digital quadrature demodulation unit 62, a band-limiting filter unit 63, and a block synchronization unit 64. Note that the configuration of the receiving processing unit 40-2 is the same as that shown in FIG. 6.

[0112] The receiving high-frequency unit 60 amplifies a radio frequency signal received via the receiving antenna 30-1 to a desired power by a low-noise amplifier, and then converts the radio frequency to an intermediate frequency. Then, the receiving high-frequency unit 60 outputs the intermediate frequency signal to the AD conversion unit 61.

[0113] The AD conversion unit 61 receives an intermediate frequency signal from the reception high frequency unit 60, converts the analog signal, which is the intermediate frequency signal, into a digital signal, and outputs the digital signal to the digital quadrature demodulation unit 62.

[0114] The digital quadrature demodulation unit 62 receives a digital signal from the AD conversion unit 61, performs automatic frequency control on the digital signal, and generates a complex baseband signal obtained by quadrature demodulation while correcting the frequency deviation. Then, the digital quadrature demodulation unit 62 outputs the complex baseband signal after frequency correction to the band-limiting filter unit 63.

[0115] The band-limiting filter unit 63 receives the complex baseband signal after frequency correction from the digital quadrature demodulation unit 62, and performs band limitation on the complex baseband signal after frequency correction by filtering. Then, the band-limiting filter unit 63 outputs the complex baseband signal after band limitation to the block synchronization unit 64. Generally, a root raised cosine filter is used as the band-limiting filter.

[0116] The block synchronization unit 64 receives the complex baseband signal after band limitation from the band-limiting filter unit 63, and detects the synchronization timing of the MIMO SC-FDE block with reference to the IQ signal of the UW part for the complex baseband signal after band limitation. Then, the block synchronization unit 64 outputs the MIMO SC-FDE block for which the synchronization timing has been detected to the MIMO block number detection unit 41-1.

[0117] Returning to FIG. 5, the MIMO block number detection unit 41-1 receives the MIMO SC-FDE block for which the synchronization timing has been detected from the block synchronization unit 64 of the reception processing unit 40-1. Then, the MIMO block number detection unit 41-1 detects the MIMO block number by performing differential demodulation by delayed detection with reference to the position (synchronization position) of the synchronization timing detected by the block synchronization unit 64 for the MIMO SC-FDE block.

[0118] The MIMO block number detector 41-1 outputs the MIMO block number to the MIMO block number comparator 42-1 and the MIMO channel estimator 44-1. Also, the MIMO block number detector 41-1 outputs the MIMO SC-FDE block to the noise power detector 43-1, the MIMO channel estimator 44-1, and the Fourier transform unit 45-1.

[0119] The MIMO block number comparator 42-1 receives the MIMO block number from the MIMO block number detector 41-1 and also receives the equalized MIMO block number from the equalized MIMO block number determination unit 50, which will be described later. Then, the MIMO block number comparator 42-1 compares the MIMO block number with the equalized MIMO block number.

[0120] When the MIMO block number comparator 42-1 determines that the MIMO block number and the equalized MIMO block number match based on the comparison result, the MIMO block number comparator 42-1 outputs the comparison result indicating a match and the MIMO block number to the MIMO channel estimator 44-1. On the other hand, when the MIMO block number comparator 42-1 determines that the MIMO block number and the equalized MIMO block number are different, the MIMO block number comparator 42-1 outputs the comparison result indicating a difference and the equalized MIMO block number to the MIMO channel estimator 44-1.

[0121] Thereby, when the MIMO block number and the equalized MIMO block number are different, the MIMO channel estimator 44-1 is controlled so that MIMO detection is performed based on the equalized MIMO block number input from the equalized MIMO block number determination unit 50 in the frequency domain MIMO channel equalizer 46, which will be described later.

[0122] The noise power detector 43-1 receives the MIMO SC-FDE block from the MIMO block number detector 41-1, measures the noise power n1 of the received signal using the MIMO SC-FDE block, and outputs the noise power n1 to the frequency domain MIMO channel equalizer 46.

[0123] The MIMO channel estimator 44-1 receives the MIMO SC-FDE block and the MIMO block number from the MIMO block number detector 41-1, and receives the comparison result, the MIMO block number, or the equalized MIMO block number from the MIMO block number comparator 42-1.

[0124] For the MIMO SC-FDE block, the MIMO channel estimator 44-1 extracts pilot signals in the time domain included in a series of MIMO SC-FDE blocks (the same number of blocks as the number of transmissions constituting the detection target block) based on the position of the synchronization timing detected by the block synchronization unit 64, according to the MIMO block number or the equalized MIMO block number corresponding to the comparison result, performs a fast Fourier transform, and estimates the MIMO channel.

[0125] After estimating the MIMO channel, the MIMO channel estimator 44-1 upsamples the MIMO channel so as to match the number of symbols (the preset number of MIMO detection range symbols SS) for which frequency domain equalization is performed by the subsequent frequency domain MIMO channel equalizer 46. Then, the MIMO channel estimator 44-1 outputs the upsampled MIMO channel (for example, when the number of transmissions is 2, the channel responses h 11 , h 12 ) to the frequency domain MIMO channel equalizer 46. The upsampled MIMO channel becomes a MIMO channel corresponding to the number of symbols (the preset number of MIMO detection range symbols SS) for which frequency domain equalization is performed.

[0126] Here, the number of symbols of the MIMO channel before upsampling is the number of pilot signal symbols c under the condition of (C) described above. The number of symbols of the MIMO channel after upsampling, that is, the number of symbols for which frequency domain equalization is performed, is the MIMO detection range symbol number SS of the formula (1) under the condition of (D) described above. For example, when the number of transmissions is 2, if the MIMO block number symbol number a = 2 and the pilot signal symbol number c = 2 8 = 256, then the MIMO detection range symbol number SS = 212 is 4096.

[0127] (Channel Estimation When the Transmission Count Is 2) When the transmission count is 2 as shown in FIG. 2, for example, the MIMO channel estimation unit 44-1 performs a fast Fourier transform on two pilot signals in the time domain (the pilot signal of the first block and the pilot signal of the second block) in the received signal y1 of the first reception system (the signal of the reception system of the reception antenna 30-1), and estimates the channel responses h 11 , h 12 .

[0128] Also, the MIMO channel estimation unit 44-2 performs a fast Fourier transform on two pilot signals in the time domain (the pilot signal of the first block and the pilot signal of the second block) in the received signal y2 of the second reception system (the signal of the reception system of the reception antenna 30-2), and estimates the channel responses h 21 , h 22 .

[0129] The MIMO channel H when the transmission count is 2 is expressed by the following equation. [Equation 2] TIFF0007702854000001.tif15170

[0130] FIG. 7 is a diagram for explaining an example of the channel estimation process, and corresponds to the case where the transmission count is 2 as shown in FIG. 2. The received signal y1 is the signal of the first reception system as described above, and the received signal y2 is the signal of the second reception system.

[0131] The MIMO channel estimation units 44-1 and 44-2 estimate the channel responses h 11 , h 12 , h 21 , h 22 .

[0132] The MIMO channel estimation unit 44-1, in the received signal y1, based on the position shifted by the FFT window offset from the end position of the latter pilot signal (the start position of the data signal) among two consecutive pilot signals, extracts the received pilot signal h 11 UW t , and the received pilot signal h 12 UW t of the second block. UW t indicates that it is a pilot signal in the time domain.

[0133] Then, the MIMO channel estimation unit 44-1 performs a fast Fourier transform on the extracted received pilot signal h 11 UW t , and divides the fast Fourier transform result by the fast Fourier transform result UW t of the pilot signal UW f to estimate the channel response h 11 . Also, the MIMO channel estimation unit 44-1 performs a fast Fourier transform on the extracted received pilot signal h 12 UW t , and divides the fast Fourier transform result by the fast Fourier transform result UW t of the pilot signal UW f to estimate the channel response h 12 .

[0134] Similarly, the MIMO channel estimation unit 44-2, in the received signal y2, based on the position shifted by the FFT window offset from the end position of the latter pilot signal (the start position of the data signal) among two consecutive pilot signals, extracts the received pilot signal h 21 UW t , and the received pilot signal h 22 UW t .

[0135] Then, the MIMO channel estimation unit 44-2 performs a fast Fourier transform on the extracted received pilot signal h 21 UW tPerform a fast Fourier transform on it, and use the fast Fourier transform result as the pilot signal UW t The fast Fourier transform result UW of f to divide, thereby estimating the channel response h 21 Also, the MIMO channel estimator 44-2 extracts the received pilot signal h 22 UW t Perform a fast Fourier transform on it, and use the fast Fourier transform result as the pilot signal UW t The fast Fourier transform result UW of f to divide, thereby estimating the channel response h 22 is estimated.

[0136] The processing example of channel estimation shown in FIG. 7 will be described using mathematical formulas. The formula for 2×2 MIMO when the number of transmissions is 2 and the number of receptions (MIMO reception number) is 2 is as follows. n1 and n2 are noise powers. [Equation 3] TIFF0007702854000002.tif16170

[0137] Within the two blocks for MIMO separation, it is assumed that the channel response h nm is constant as shown in the following equation. [Equation 4] h nm =h nm (t = 0)=h nm (t = 1) ···(4) t = 0 indicates the first block, and t = 1 indicates the second block. n = 1, 2, m = 1, 2.

[0138] Regarding the received signal y1 of the first receiving system, the received signal y of the first block 1t=0 and the received signal y of the second block 1t=1 are represented by the following equation. [Equation 5] TIFF0007702854000003.tif16170

[0139] This equation is transformed into the following equation. [Equation 6] TIFF0007702854000004.tif27170

[0140] That is, the channel response h 11 , h 12 is expressed by the following equation when ignoring the noise power n 1t=0 , n 1t=1 : [Equation 7] TIFF0007702854000005.tif54170

[0141] Thus, for the received signal y1 of the first receiving system, the channel response h 1t=0 , y 1t=1 is obtained from the received signals y 11 , h 12 of two consecutive blocks by the above equation.

[0142] Similarly, for the received signal y2 of the second receiving system, the channel response h 2t=0 , y 2t=1 is obtained from the received signals y 21 , h 22 of two consecutive blocks by the same equation as above.

[0143] (Channel Estimation in the Case of Transmission Number 4) Next, the channel estimation in the case of transmission number 4 will be described. As described above, in the symbol block configuration example of the MIMO SC-FDE system when the transmission number is 4, there are an example of a UW diagonal structure in which two consecutive UWs shown in FIG. 3 are arranged diagonally, and an example of a null data diagonal structure in which the null data shown in FIG. 4 is arranged diagonally. It is assumed that which diagonal structure to use is preset in the transmitting device 1 and the receiving device 2.

[0144] If the pilot signal groups having a UW diagonal structure or a null data diagonal structure are preset in the transmission device 1 and the reception device 2, they may be rearranged among the transmission signals x1, x2, x3, and x4. For example, in FIG. 3, the pilot signal group of the transmission signal x1 and the pilot signal group of the transmission signal x2 may be swapped. In this case, although the pilot signal group after the swap is not formally a UW diagonal structure, by restoring the pilot signal group of the transmission signal x1 and the pilot signal group of the transmission signal x2 to their original states, the pilot signal group becomes a UW diagonal structure.

[0145] That is, the diagonal here means that when the pilot signal groups are rearranged among the transmission signals x1, x2, x3, and x4, they form a diagonal relationship (UW diagonal structure or null data diagonal structure).

[0146] Assume that pilot signals are extracted from each of the same number of blocks as the transmission number 4 in the transmission signals x1, x2, x3, and x4, and a matrix composed of the pilot signal groups is formed.

[0147] If two consecutive UWs are set to "1" and the null data corresponding to two consecutive UWs is set to "0", then in the case of the UW diagonal structure in FIG. 3, the pilot signal group is represented by the following matrix. [Number 8] TIFF0007702854000006.tif26170

[0148] Also, in the case of the null data diagonal structure in FIG. 4, the pilot signal group is represented by the following matrix. [Number 9] TIFF0007702854000007.tif26170

[0149] In the case of the UW diagonal structure in FIG. 3, by expanding the processing example of channel estimation shown in FIG. 7, the channel responses h 11 , h 12 , h 13 , h 14 etc. are estimated.

[0150] Specifically, with the transmission number being 4 and the reception number being 4, the MIMO channel estimator 44-1 extracts the received pilot signals h 11 UW t , h 12 UW t , h 13 UW t , h 14 UW t from the received signal y1.

[0151] Then, the MIMO channel estimator 44-1 performs a fast Fourier transform on each of the extracted received pilot signals h 11 UW t , h 12 UW t , h 13 UW t , h 14 UW t and divides each fast Fourier transform result by the fast Fourier transform result UW t of the pilot signal UW f to estimate the channel responses h 11 , h 12 , h 13 , h 14 .

[0152] The MIMO channel estimator 44-2 performs the same process on the received signal y2 to estimate the channel responses h 21 , h 22 , h 23 , h 24 . Similarly, the MIMO channel estimator 44-3 estimates the channel responses h 31 , h 32 , h 33 , h 34 from the received signal y3, and the MIMO channel estimator 44-4 estimates the channel responses h 41 , h 42 , h 43 , h 44 .

[0153] Also, in the case of the null data diagonal structure in FIG. 4, by solving a system of four linear equations for each of the received signals y1, y2, y3, and y4, the channel responses h 11 , h 12 , h 13 , h 14 etc. are estimated.

[0154] That is, the MIMO channel estimator 44-1 etc. extracts the received pilot signals included in the same number of blocks as the number of transmissions 4 that make up the detection target block, performs fast Fourier transform on each of the four received pilot signals, and based on the fast Fourier transform results of the four received pilot signals and the fast Fourier transform result of the UW in the time domain, as shown in Equation (22) described later, the channel responses h 11 , h 12 , h 13 , h 14 etc. are estimated.

[0155] By the way, the condition for enabling channel estimation from the received signals y1, y2, y3, and y4 is that the rank of this matrix is the same as the number of transmissions 4, as shown in the following equation. [Equation 10] It becomes TIFF0007702854000008.tif27170.

[0156] Even when the pilot signal group having a UW diagonal structure or a null data diagonal structure is rearranged among the transmission signals x1, x2, x3, and x4, since the rank of the matrix is 4, the condition for enabling channel estimation from the received signals y1, y2, y3, and y4 is satisfied.

[0157] Also, for example, in FIG. 4, assume a case where only the pilot signals of the fourth block of the transmission signal x2, the third block of the transmission signal x3, and the second block of the transmission signal x4 are null data, and the rest are UW.

[0158] The pilot signal group in this case is represented by the following matrix, and the rank is also 4. [Equation 11] TIFF0007702854000009.tif27170[Number 12] TIFF0007702854000010.tif27170

[0159] However, the power of the pilot signal is biased among the transmission signals x1, x2, x3, x4, and a MIMO channel with a bias in accuracy is estimated among the transmission signals x1, x2, x3, x4, resulting in deterioration of the transmission performance.

[0160] Therefore, the condition for enabling channel estimation is that the matrix of the pilot signal group is the same as the number of transmissions, that is, there is no rank deficiency. However, in order for the power of the pilot signal not to be biased among the transmission signals x1, x2, x3, x4, it is desirable that the pilot signal group has a UW diagonal structure in FIG. 3 or a null data diagonal structure in FIG. 4.

[0161] Hereinafter, a processing example of channel estimation in the case where the number of transmissions is 4 and the number of receptions is 4 will be described using mathematical formulas. The formula for 4×4 MIMO in this case is as follows. n1, n2, n3, n4 are noise powers. [Number 13] TIFF0007702854000011.tif56170

[0162] Within the four blocks for MIMO separation, the channel response h nm is assumed to be constant as shown in the following formula. [Number 14] h nm =h nm (t = 0)=h nm (t = 1)=h nm (t = 2)=h nm (t = 3) ··(14) t = 0 indicates the first block, t = 1 indicates the second block, t = 2 indicates the third block, and t = 3 indicates the fourth block. n = 1, 2, 3, 4, m = 1, 2, 3, 4.

[0163] (UW diagonal structure) Next, the channel estimation in the example of the UW diagonal structure when the number of transmissions shown in Fig. 3 is 4 will be described. For the received signal y1 of the first receiving system, the received signals y of four consecutive blocks 1t=0 ,y 1t=1 ,y 1t=2 ,y 1t=3 are represented by the following equation. [Equation 15] TIFF0007702854000012.tif28170

[0164] This equation is transformed into the following equation. [Equation 16] TIFF0007702854000013.tif48170

[0165] That is, the channel responses h 11 ,h 12 ,h 13 ,h 14 are represented by the following equation when the noise powers n 1t=0 ,n 1t=1 ,n 1t=2 ,n 1t=3 are ignored. [Equation 17] TIFF0007702854000014.tif89170

[0166] Thus, for the received signal y1, the channel responses h 1t=0 ,y 1t=1 ,y 1t=2 ,y 1t=3 are obtained from the received signals y of four consecutive blocks. 11 ,h 12 ,h 13 ,h 14

[0167] For the received signal y2 as well, the channel responses h 2t=0 ,y 2t=1 ,y 2t=2 ,y 2t=3 are obtained from the received signals y of four consecutive blocks in the same equation as described above. 21 ,h 22 ,h 23 ,h 24 ​is required. Also, for the received signal y3, the channel responses h 3t=0 ,y 3t=1 ,y 3t=2 ,y 3t=3 from the received signals of four consecutive blocks y 31 ,h 32 ,h 33 ,h 34 are required. Also, for the received signal y4, the channel responses h 4t=0 ,y 4t=1 ,y 4t=2 ,y 4t=3 from the received signals of four consecutive blocks y 41 ,h 42 ,h 43 ,h 44 are required.

[0168] (Null Data Diagonal Structure) Next, the channel estimation in the example of the null data diagonal structure when the number of transmissions shown in FIG. 4 is 4 will be described. For the received signal y1 of the first receiving system, the received signals y 1t=0 ,y 1t=1 ,y 1t=2 ,y 1t=3 of four consecutive blocks are represented by the following equation. [Equation 18] TIFF0007702854000015.tif32170

[0169] This equation is transformed into the following equation. [Equation 19] TIFF0007702854000016.tif50170[Equation 20] TIFF0007702854000017.tif49170

[0170] That is, the channel responses h 11 ,h 12 ,h 13 ,h 14 are represented by the following equation. [Equation 21] TIFF0007702854000018.tif49170

[0171] Also, for the channel response h 11 , h 12 , h 13 , h 14 ignoring the noise power n 1t=0 , n 1t=1 , n 1t=2 , n 1t=3 is expressed by the following formula. [Equation 22] TIFF0007702854000019.tif97170

[0172] Thus, for the received signal y1, from the received signals y of four consecutive blocks in the above formula 1t=0 , y 1t=1 , y 1t=2 , y 1t=3 the channel response h 11 , h 12 , h 13 , h 14 is obtained.

[0173] For the received signal y2 as well, from the received signals y of four consecutive blocks in the same formula as above 2t=0 , y 2t=1 , y 2t=2 , y 2t=3 the channel response h 21 , h 22 , h 23 , h 24 is obtained. Also, for the received signal y3 as well, from the received signals y of four consecutive blocks in the same formula as above 3t=0 , y 3t=1 , y 3t=2 , y 3t=3 the channel response h 31 , h 32 , h 33 , h 34 is obtained. Also, for the received signal y4 as well, from the received signals y of four consecutive blocks in the same formula as above 4t=0 , y 4t=1 , y 4t=2 , y 4t=3 the channel response h 41 , h 42 , h 43 , h 44 is obtained.

[0174] Further, when comparing the aforementioned formula (17) showing the channel estimation process of the UW diagonal structure with the aforementioned formula (22) showing the channel estimation process of the null data diagonal structure, the channel estimation process of the UW diagonal structure requires less processing load than that of the null data diagonal structure.

[0175] On the other hand, from FIGS. 3 and 4, the reception frequency of the pilot signal is higher in the null data diagonal structure than in the UW diagonal structure. For this reason, the detection accuracy of the block synchronization timing in the aforementioned reception processing unit 40-1 etc. is higher in the null data diagonal structure than in the UW diagonal structure.

[0176] Returning to FIG. 5, the Fourier transform unit 45-1 inputs the MIMO SC-FDE block from the MIMO block number detection unit 41-1. Then, the Fourier transform unit 45-1 corresponds to the number of symbols (predetermined MIMO detection range symbol number SS) for frequency domain equalization performed by the subsequent frequency domain MIMO channel equalization unit 46 in a series of MIMO SC-FDE blocks. The time domain MIMO block number symbol series, data symbol series, pilot signal series, pilot signal series, MIMO block number symbol series, data symbol series, ···, MIMO block number symbol series, data symbol series, and pilot signal series are shifted and extracted by the same amount as the FFT window offset of the MIMO channel estimation unit 44-1, and these symbol series are subjected to a fast Fourier transform in the frequency domain.

[0177] The Fourier transform unit 45-1 outputs a frequency domain signal (for example, when the number of transmissions is 2, the frequency domain signal r1(f)) to the frequency domain MIMO channel equalization unit 46.

[0178] Here, the number of symbols for performing frequency domain equalization is the MIMO detection range symbol number SS of the aforementioned formula (1) under the condition of (D).

[0179] The Fourier transform unit 45-1 performs a fast Fourier transform in the frequency domain for, for example, when the number of transmissions shown in FIG. 2 is 2, in the received signal y1 of the first reception system, in units of the MIMO block number symbol series, data symbol series, pilot signal series, pilot signal series, MIMO block number symbol series, data symbol series, and pilot signal series in the time domain corresponding to the number of MIMO detection range symbols SS = 4096 which is the number of symbols for performing frequency domain equalization.

[0180] Here, for example, when the number of transmissions is 2, the noise power detection unit 43-2 outputs the noise power n2, the MIMO channel estimation unit 44-2 outputs the channel responses h 21 ,h 22 , and the Fourier transform unit 45-2 outputs the frequency domain signal r2(f) to the frequency domain MIMO channel equalization unit 46, respectively.

[0181] The frequency domain MIMO channel equalization unit 46 inputs the noise power n1 from the noise power detection unit 43-1 and the channel responses h 11 ,h 12 when the number of transmissions is 2, for example. Further, the frequency domain MIMO channel equalization unit 46 inputs the frequency domain signal r1(f) from the Fourier transform unit 45-1. Also, the frequency domain MIMO channel equalization unit 46 inputs the noise power n2 from the noise power detection unit 43-2 and the channel responses h 21 ,h 22 and further inputs the frequency domain signal r2(f) from the Fourier transform unit 45-2.

[0182] The frequency domain MIMO channel equalization unit 46 equalizes (separates) the transmitted signals x1 and x2 mixed in the frequency domain signals r1(f) and r2(f) using criteria such as the zero forcing (ZF) criterion or the minimum mean square error (MMSE) criterion based on the noise powers n1, n2, the channel responses h 11 ,h 12 ,h 21 ,h 22 , and the frequency domain signals r1(f) and r2(f).

[0183] That is, the frequency-domain MIMO channel equalizer 46 equalizes the mixed transmission signals x1 and x2 by using the MIMO channel H corresponding to the number of symbols (predetermined MIMO detection range symbol number SS) for which frequency-domain equalization is performed, and the MIMO block number symbol sequence, data symbol sequence, pilot signal sequence, pilot signal sequence, MIMO block number symbol sequence, data symbol sequence, ···, MIMO block number symbol sequence, data symbol sequence, and pilot signal sequence (and noise power) in the frequency domain corresponding to the number of symbols (predetermined MIMO detection range symbol number SS) for which frequency-domain equalization is performed.

[0184] The frequency-domain MIMO channel equalizer 46 outputs the equalized frequency-domain signal x1^(f) corresponding to the transmission signal x1 to the inverse Fourier transform unit 47-1 and outputs the equalized frequency-domain signal x2^(f) corresponding to the transmission signal x2 to the inverse Fourier transform unit 47-2.

[0185] For example, when using the zero-forcing criterion, the frequency-domain MIMO channel equalizer 46 performs MIMO channel equalization by the following formula based on the MIMO channel H (channel response h 11 , h 12 , h 21 , h 22 ) and the frequency-domain signal r(f) (r1(f), r2(f)), and obtains the equalized frequency-domain signal x^(f) (x1^(f), x2^(f)). [Equation 23] TIFF0007702854000020.tif13170

[0186] Also, when using the minimum mean square error criterion, the frequency-domain MIMO channel equalizer 46 uses the noise power σ 2 , the MIMO channel H (channel response h 11 , h 12 , h 21 , h 22Based on the signals r(f) (r1(f), r2(f)) in the frequency domain, perform MIMO channel equalization using the following formula to obtain the equalized signals x^(f) (x1^(f), x2^(f)) in the frequency domain. The noise power σ 2 is calculated based on the noise powers n1 and n2. [Equation 24] Let the number of transmissions be N for TIFF0007702854000021.tif13170 t and the number of receptions be N r and N r Let the N-by-N identity matrix be I Nr and so on.

[0187] Here, the signal r(f) in the frequency domain is represented by the following formula. [Equation 25] For TIFF0007702854000022.tif19170

[0188] Also, the equalized signal x^(f) in the frequency domain is represented by the following formula. [Equation 26] For TIFF0007702854000023.tif18170

[0189] The inverse Fourier transform unit 47-1 receives the equalized signal x1^(f) in the frequency domain corresponding to the transmission signal x1 from the frequency domain MIMO channel equalization unit 46, converts the equalized signal x1^(f) in the frequency domain into the time domain, and outputs the signal in the time domain corresponding to the transmission signal x1 to the symbol decision / likelihood calculation unit 48-1.

[0190] The equalized signal in the frequency domain corresponding to the transmission signal x1 is a series of MIMO block number symbols, data symbol series, pilot signal series, pilot signal series, MIMO block number symbol series, data symbol series, ···, MIMO block number symbol series, data symbol series, and pilot signal series in the frequency domain corresponding to the number of symbols (the preset number of MIMO detection range symbols SS) for which frequency domain equalization has been performed.

[0191] In addition, the time-domain signal corresponding to the transmission signal x1 is a series of MIMO block number symbols, data symbol series, pilot signal series, pilot signal series, MIMO block number symbol series, data symbol series, ···, MIMO block number symbol series, data symbol series, and pilot signal series in the time domain corresponding to the number of symbols (predetermined MIMO detection range symbol number SS) for which frequency-domain equalization has been performed.

[0192] The symbol determination / likelihood calculation unit 48-1 inputs the time-domain signal corresponding to the transmission signal x1 from the inverse Fourier transform unit 47-1, extracts the MIMO block number symbol series and the data symbol series from the time-domain signal, and performs demapping and likelihood calculation on these series.

[0193] The symbol determination / likelihood calculation unit 48-1 outputs the metric series of the transmission signal x1 corresponding to the MIMO block number symbol series to the equalized MIMO block number decoder 49-1 after equalization. Also, the symbol determination / likelihood calculation unit 48-1 outputs the metric series of the transmission signal x1 corresponding to the information bit series (data subjected to error correction coding) constituting the data symbol series to the inner deinterleaver 51-1. The metric series can use the bit series after hard decision, likelihood, quantized likelihood, etc.

[0194] The equalized MIMO block number decoder 49-1 inputs the metric series of the transmission signal x1 corresponding to the MIMO block number symbol series from the symbol determination / likelihood calculation unit 48-1, extracts the value corresponding to the MIMO block number from the metric series, and outputs this as the equalized MIMO block number corresponding to the transmission signal x1 to the equalized MIMO block number determination unit 50.

[0195] The equalized MIMO block number determination unit 50 inputs the equalized MIMO block number corresponding to the transmission signal x1 from the equalized MIMO block number decoder 49-1 and inputs the equalized MIMO block number corresponding to the transmission signal x2 from the equalized MIMO block number decoder 49-2.

[0196] After equalization, the MIMO block number determination unit 50 compares these equalized MIMO block numbers. If these equalized MIMO block numbers match, it outputs the equalized MIMO block number to the MIMO block number comparison units 42-1 and 42-2. On the other hand, when the equalized MIMO block numbers do not match, after shifting the synchronization position of the block numbers forward and backward, the MIMO block number determination unit 50 causes the MIMO block number detection units 41-1, 41-2, etc. to re-perform the processes after MIMO block number detection.

[0197] Here, in the MIMO block number comparison units 42-1 and 42-2, when the MIMO block number input from the MIMO block number detection units 41-1 and 41-2 does not match the equalized MIMO block number input from the equalized MIMO block number determination unit 50, the MIMO channel H (channel response h 11 , h 12 , h 21 , h 22 ) estimated by the MIMO channel estimation units 44-1 and 44-2 will be described.

[0198] When the MIMO block number and the equalized MIMO block number do not match, each element of the MIMO channel H estimated by the MIMO channel estimation units 44-1 and 44-2 will be swapped. In the case of the example shown in FIG. 2, the channel response h 11 and the channel response h 12 will be swapped, and the channel response h 21 and the channel response h 22 will be swapped.

[0199] Therefore, when the MIMO channel estimation unit 44-1 inputs a comparison result indicating a mismatch from the MIMO block number comparison unit 42-1, the estimated channel responses h 11 and the channel response h 12These are swapped and output. Further, when the MIMO channel estimation unit 44-2 receives a comparison result indicating a mismatch from the MIMO block number comparison unit 42-2, the estimated channel response h 21 and the channel response h 22 These are swapped and output. As a result, normal MIMO channel estimation becomes possible.

[0200] Note that the MIMO block number detection units 41-1 and 41-2 may interrupt the detection process for one block and then resume it so as to detect a normal MIMO block number.

[0201] The inner deinterleaver unit 51-1 receives a metric sequence of the transmission signal x1 corresponding to the information bit sequence constituting the data symbol sequence from the symbol determination / likelihood calculation unit 48-1, performs the reverse process of the inner interleaver unit 12-1 shown in FIG. 1 on the metric sequence, and outputs the metric sequence of the transmission signal x1 after inner deinterleaving to the decoder 52.

[0202] The decoder 52 receives the metric sequence of the transmission signal x1 after inner deinterleaving from the inner deinterleaver unit 51-1 and the metric sequence of the transmission signal x2 after inner deinterleaving from the inner deinterleaver unit 51-2. Then, the decoder 52 performs a process of returning these metric sequences to one sequence in a form corresponding to the inter-system distribution unit 11 shown in FIG. 1. Then, the decoder 52 performs deinterleaving processing, error correction decoding processing, energy despreading processing, etc. corresponding to the pre-transmission processing unit 10 shown in FIG. 1, decodes the metric sequence after these processes, and outputs the original information bit sequence.

[0203] As described above, according to the receiving apparatus 2 of the embodiment of the present invention, a modulated wave transmitted from the transmitting apparatus 1 shown in FIG. 1 is received. The MIMO channel estimation unit 44-1 extracts the received pilot signal h 11 UW t from the received signal y1, performs a fast Fourier transform on it, and uses the fast Fourier transform result as the fast Fourier transform result UW t of the pilot signal UWf By dividing by f , the channel response h 11 is estimated. Also, the MIMO channel estimator 44-1 extracts the received pilot signal h 12 UW t from the received signal y1 for the second block, performs a fast Fourier transform on it, and divides the fast Fourier transform result by the fast Fourier transform result UW t of the pilot signal UW f to estimate the channel response h 12 .

[0204] Similarly, the MIMO channel estimator 44-2 extracts the received pilot signal h 21 UW t from the received signal y2 for the first block, performs a fast Fourier transform on it, and divides by UW f to estimate the channel response h 21 . Also, the MIMO channel estimator 44-2 extracts the received pilot signal h 22 UW t from the received signal y2 for the second block, performs a fast Fourier transform on it, and divides the transform result by UW f to estimate the channel response h 22 .

[0205] After the MIMO channel estimators 44-1 and 44-2 estimate the MIMO channel H (channel responses h 11 , h 12 , h 21 , h 22 ), they perform upsampling of the MIMO channel H so that it matches the number of symbols for performing frequency domain equalization (the preset number of MIMO detection range symbols SS in the condition (D) above).

[0206] The Fourier transform units 45-1 and 45-2 perform a fast Fourier transform on the MIMO block number symbol sequence, data symbol sequence, etc. in the time domain corresponding to the number of symbols for performing frequency domain equalization (the preset number of MIMO detection range symbols SS in the condition (D) above) into the frequency domain.

[0207] The frequency-domain MIMO channel equalizer 46 equalizes the mixed transmission signals x1 and x2 using the MIMO channel H, the MIMO block number symbol sequence in the frequency domain corresponding to the number of symbols for which frequency-domain equalization is performed (the preset MIMO detection range symbol number SS in the condition (D) above), the data symbol sequence, etc. (and the noise power).

[0208] The inverse Fourier transform units 47-1 and 47-2 perform a fast inverse Fourier transform on signals such as the MIMO block number symbol sequence and the data symbol sequence in the frequency domain corresponding to the number of symbols for which frequency-domain equalization has been performed (the preset MIMO detection range symbol number SS in the condition (D) above) into the time domain.

[0209] Here, since the number of pilot signal symbols c is a power of 2, the received pilot signal can be fast Fourier-transformed in the MIMO channel estimation units 44-1 and 44-2. Also, since the MIMO detection range symbol number SS is a power of 2, the MIMO detection range can be fast Fourier-transformed and fast inverse Fourier-transformed in the Fourier transform units 45-1 and 45-2 and the inverse Fourier transform units 47-1 and 47-2.

[0210] Furthermore, even when the MIMO detection range is shifted forward or there are delayed waves, as shown in FIGS. 2 to 4, since the latter (second) UW of the two consecutive UWs also serves as the CP, these effects are not received even when converted into the frequency domain. That is, the MIMO channel can be accurately estimated and the MIMO channel equalization can be accurately performed.

[0211] Therefore, when performing MIMO transmission using the SC-FDE method, since the ratio of effective data increases with respect to all transmission signals, the transmission rate can be made higher than the prior art when compared at the same symbol rate, and the transmission efficiency can be improved.

[0212] Also, the pilot signal is composed of UW and null data. In the examples shown in FIGS. 2 and 3, two consecutive UWs are arranged diagonally, and the other pilot signals are null data. Also, in the example shown in FIG. 4, null data is arranged diagonally, and the other pilot signals are UW.

[0213] As a result, since the power of the pilot signal does not deviate between transmission signals, on the receiving side, it is possible to estimate an MIMO channel with no deviation in accuracy between transmission signals, and it is possible to obtain equal reception performance between transmission signals.

[0214] As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical idea thereof.

[0215] For example, in the above embodiments, examples of the number of transmissions being 2 and 4 have been described. However, the number of transmissions may be a plurality other than 2 and 4. Also, in the above embodiments, examples of the number of receptions being 2 and 4 have been described. However, the number of receptions may be a single number, or may be a plurality other than 2 and 4.

Industrial Applicability

[0216] The transmission device 1 and the reception device 2 according to the embodiments of the present invention are useful for a wireless transmission system such as broadcasting or communication that performs MIMO transmission using the SC-FDE method.

Explanation of Signs

[0217] 1 Transmission device (single carrier MIMO transmission device) 2 Reception device (single carrier MIMO reception device) 10 Transmission preprocessing unit 11 Inter-system distribution unit 12 Inner interleaving unit 13 Mapping unit 14 MIMO block number insertion unit 15 Pilot signal insertion unit 16, 63 Band-limiting filter unit 17 Digital Orthogonal Modulation Unit 18 DA Conversion Unit 19 Transmitting High-Frequency Unit 20 Transmitting Antenna 30 Receiving Antenna 40 Receiving Processing Unit 41 MIMO Block Number Detection Unit 42 MIMO Block Number Comparison Unit 43 Noise Power Detection Unit 44 MIMO Channel Estimation Unit 45 Fourier Transform Unit 46 Frequency-Domain MIMO Channel Equalization Unit 47 Inverse Fourier Transform Unit 48 Symbol Decision / Likelihood Calculation Unit 49 Equalized MIMO Block Number Decoding Unit 50 Equalized MIMO Block Number Decision Unit 51 Inner Deinterleaver 52 Decoding Unit 60 Receiving High-Frequency Unit 61 AD Conversion Unit 62 Digital Orthogonal Demodulation Unit 64 Block Synchronization Unit a Number of Symbols in MIMO Block Number b Number of Data Symbols c Number of Pilot Signal Symbols d Number of Transmissions Number of Symbols in SS MIMO Detection Range α Detection Target Block

Claims

1. In a single-carrier MIMO transmission apparatus that includes a plurality of transmission antennas and generates a block of the MIMO SC-FDE method for each of a plurality of transmission systems corresponding to the plurality of transmission antennas, and transmits a modulated wave of the block for each transmission system via the transmission antenna, an inter-system allocation unit that allocates to the plurality of transmission systems a coded bit sequence of data to be transmitted; a mapping unit for each transmission system that performs mapping on the coded bit sequence of the data to be transmitted allocated by the inter-system allocation unit by a predetermined modulation method and outputs a bit sequence after mapping; a MIMO block number insertion unit for each transmission system that inserts a MIMO block number at a predetermined position in the bit sequence after mapping output by the mapping unit and outputs a symbol sequence in which the MIMO block number is inserted; a pilot signal insertion unit for each transmission system that inserts two consecutive pilot signals at a predetermined position in the symbol sequence in which the MIMO block number is inserted output by the MIMO block number insertion unit, and generates a symbol sequence of a detection target block composed of the same number of the blocks as the number of transmission systems, with the block composed of the two consecutive pilot signals, the MIMO block number, and the data to be transmitted as a unit; wherein the number of symbols of the MIMO block number is defined as a MIMO block number symbol number a, the number of symbols of the data to be transmitted is defined as a data symbol number b, the number of symbols of the pilot signal is defined as a pilot signal symbol number c, the number of the plurality of transmission antennas is defined as a MIMO transmission number d, and the number of symbols of a MIMO detection range in which equalization is performed in a frequency domain is defined as a MIMO detection range symbol number SS; the MIMO detection range is defined as a range from the MIMO block number included in the first block in the detection target block to the first pilot signal included in the first block in the next detection target block of the detection target block; the pilot signal insertion unit, when a matrix is configured with the two consecutive pilot signals included in the detection target block in the plurality of transmission systems as one element, two consecutive UW (unique word) elements composed of signals of a known fixed pattern are arranged on the diagonal line of the matrix (A), Of all the pilot signals constituting the matrix, the pilot signals other than the two consecutive UW signals arranged on the diagonal are null data (B), The number of pilot signal symbols c is a power of 2 (C), The number of symbols SS in the MIMO detection range is a power of 2 and is represented by the mathematical formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). The two consecutive pilot signals are inserted at a predetermined position to generate a symbol sequence of the detection target block. A single-carrier MIMO transmission apparatus characterized by this.

2. In a single-carrier MIMO transmission apparatus that includes a plurality of transmission antennas and generates a block of the MIMO SC-FDE method for each of a plurality of transmission systems corresponding to the plurality of transmission antennas, and transmits a modulated wave of the block for each transmission system via the transmission antenna, An inter-system allocation unit that allocates to the plurality of transmission systems the coded bit sequence of the data to be transmitted, A mapping unit for each transmission system that performs mapping on the coded bit sequence of the data to be transmitted allocated by the inter-system allocation unit by a predetermined modulation method and outputs the bit sequence after mapping, An MIMO block number insertion unit for each transmission system that inserts an MIMO block number at a predetermined position in the bit sequence after mapping output by the mapping unit and outputs a symbol sequence in which the MIMO block number is inserted, A pilot signal insertion unit for each transmission system that inserts two consecutive pilot signals at a predetermined position in the symbol sequence in which the MIMO block number is inserted output by the MIMO block number insertion unit, and generates a symbol sequence of a detection target block composed of the same number of blocks as the number of transmission systems, with the two consecutive pilot signals, the MIMO block number, and the data to be transmitted as a unit. Let the number of symbols of the MIMO block number be the MIMO block number symbol number a, the number of symbols of the data to be transmitted be the data symbol number b, the number of symbols of the pilot signal be the pilot signal symbol number c, the number of the plurality of transmission antennas be the MIMO transmission number d, and the number of symbols of the MIMO detection range where equalization is performed in the frequency domain be the MIMO detection range symbol number SS. Define the MIMO detection range as the range from the MIMO block number included in the first block in the detection target block to the leading pilot signal included in the first block in the next detection target block of the detection target block. The pilot signal insertion unit When a matrix is formed with two consecutive pilot signals included in the detection target block in the plurality of transmission systems as one element, the elements of null data are arranged on the diagonal of the matrix (A). Among all the pilot signals constituting the matrix, the pilot signals other than the null data arranged on the diagonal are two consecutive UW (Unique Word) consisting of signals of a known fixed pattern (B). The pilot signal symbol number c is a power of 2 (C). The MIMO detection range symbol number SS is a power of 2 and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). Insert the two consecutive pilot signals at a predetermined position to generate a symbol sequence of the detection target block. A single-carrier MIMO transmission apparatus characterized by the above.

3. A single-carrier MIMO receiving apparatus comprising one or more receiving antennas, receiving a modulated wave transmitted from a plurality of transmitting antennas provided in a single-carrier MIMO transmitting apparatus via the one or more receiving antennas in corresponding one or more receiving systems, estimating a MIMO channel based on a received pilot signal included in a received signal in which MIMO SC-FDE blocks are multiplexed, and performing equalization in the frequency domain. The block is composed of two consecutive pilot signals, a MIMO block number, and data. Let the number of symbols of the MIMO block number be the MIMO block number symbol number a, the number of symbols of the data be the data symbol number b, the number of symbols of the pilot signal be the pilot signal symbol number c, the number of the plurality of transmit antennas be the MIMO transmission number d, and the number of symbols of the MIMO detection range where equalization is performed in the frequency domain be the MIMO detection range symbol number SS. Assume that the detection target block is composed of the same number of blocks as the MIMO transmission number d, and the MIMO detection range is defined as the range from the MIMO block number included in the first block of the detection target block to the first pilot signal included in the first block of the next detection target block of the detection target block. When a matrix is formed with two consecutive pilot signals included in the detection target block in a plurality of transmission systems of the single-carrier MIMO transmission apparatus as one element, two consecutive UW (Unique Word) elements composed of signals of a known fixed pattern are arranged on the diagonal of the matrix (A). Among all the pilot signals constituting the matrix, the pilot signals other than the two consecutive UW arranged on the diagonal are null data (B). The pilot signal symbol number c is a power of 2 (C). The MIMO detection range symbol number SS is a power of 2 and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block of the detection target block are the same (E). A MIMO channel estimator for each receiving system that performs fast Fourier transform on the pilot signal, estimates the MIMO channel, upsamples the MIMO channel so as to match the preset MIMO detection range symbol number SS, and outputs the upsampled MIMO channel. A Fourier transform unit for each receiving system that performs fast Fourier transform on the MIMO detection range corresponding to the preset MIMO detection range symbol number SS and outputs a signal in the frequency domain. The upsampled MIMO channel output by the MIMO channel estimator for each of the receiving systems, and the signal in the frequency domain output by the Fourier transform unit for each of the receiving systems are respectively input, and the upsampled MIMO channel and the signal in the frequency domain corresponding to the preset number of symbols SS in the MIMO detection range are used to perform MIMO channel equalization in the frequency domain, a frequency domain MIMO channel equalization unit, and The MIMO channel estimator extracts the received pilot signals included in the same number of blocks as the MIMO transmission number d constituting the detection target block from the signals received by the receiving system, performs a fast Fourier transform on the received pilot signals, and divides the fast Fourier transform result of the received pilot signals by the fast Fourier transform result of the UW in the time domain, thereby estimating the channel response between each of the plurality of transmitting antennas and the receiving antenna of the receiving system. A single-carrier MIMO receiving apparatus characterized by

4. In a single-carrier MIMO receiving apparatus that includes one or more receiving antennas, receives modulated waves transmitted from a plurality of transmitting antennas provided in a single-carrier MIMO transmitting apparatus via the one or more receiving antennas in corresponding one or more receiving systems, estimates a MIMO channel based on received pilot signals included in a received signal in which blocks of the MIMO SC-FDE scheme are multiplexed, and performs equalization in the frequency domain, the block is composed of two consecutive pilot signals, a MIMO block number, and data, the number of symbols of the MIMO block number is defined as the MIMO block number symbol number a, the number of symbols of the data is defined as the data symbol number b, the number of symbols of the pilot signal is defined as the pilot signal symbol number c, the number of the plurality of transmitting antennas is defined as the MIMO transmission number d, and the number of symbols in the MIMO detection range where equalization is performed in the frequency domain is defined as the MIMO detection range symbol number SS, It is assumed that the detection target block is composed of the same number of blocks as the MIMO transmission number d, and the MIMO detection range is from the MIMO block number included in the first block in the detection target block to the first pilot signal included in the first block in the next detection target block of the detection target block. When a matrix is configured with two consecutive pilot signals included in the detection target block in a plurality of transmission systems of the single-carrier MIMO transmission apparatus as one element, elements of null data are arranged on the diagonal of the matrix (A). Among all the pilot signals constituting the matrix, the pilot signals other than the null data arranged on the diagonal are two consecutive UW (Unique Word) consisting of signals of a known fixed pattern (B). The pilot signal symbol number c is a power of 2 (C). The MIMO detection range symbol number SS is a power of 2, and is represented by the formula: SS = (a + b) × d + c × (2 × d - 1) (D), and the two consecutive pilot signals included in the first block in the detection target block are the same (E). A MIMO channel estimator for each receiving system that performs fast Fourier transform on the pilot signal, estimates the MIMO channel, upsamples the MIMO channel so as to match the preset MIMO detection range symbol number SS, and outputs the upsampled MIMO channel. A Fourier transform unit for each receiving system that performs fast Fourier transform on the MIMO detection range corresponding to the preset MIMO detection range symbol number SS and outputs a signal in the frequency domain. A frequency domain MIMO channel equalization unit that inputs the upsampled MIMO channel output by the MIMO channel estimator for each receiving system and the signal in the frequency domain output by the Fourier transform unit for each receiving system, and performs MIMO channel equalization in the frequency domain using the upsampled MIMO channel and the signal in the frequency domain corresponding to the preset MIMO detection range symbol number SS. The MIMO channel estimator is Extract the received pilot signals included in the same number of blocks as the MIMO transmission number d that constitutes the detection target block from the signal received by the reception system, perform fast Fourier transform on each of the received pilot signals in the same number as the MIMO transmission number d, and based on the fast Fourier transform results of these received pilot signals and the fast Fourier transform result of the UW in the time domain, estimate the channel response between each of the plurality of transmission antennas and the reception antenna of the reception system. A single-carrier MIMO reception apparatus characterized by this.

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