JP4387989B2 - Receiver - Google Patents

Description

  The present invention relates to a receiving apparatus capable of separately receiving radio signals from a plurality of users existing in the same frequency channel using a plurality of antennas in a digital radio communication system.

  One of the methods for separating and receiving radio signals from multiple users existing on the same frequency channel using multiple antennas. The transmission signal is independent of each user on the transmission side and is known to each other on the transmission side and reception side. There is a technique in which a preamble is added, a transfer function is estimated using the preamble on the receiving side, and separate reception is performed based on the estimated transfer function. However, particularly in packet communication, there is a problem that the throughput is greatly reduced due to the assigned preamble, and when communication is performed to assign an independent preamble for each user, the throughput is further reduced due to the communication. there were.

  Therefore, in packet communication, when radio signals from a plurality of users existing on the same frequency channel are separated and received using a plurality of antennas, the transmission side is independent of the transmission signal for each user and the transmission side and the reception side are mutually independent. There is a need for a technique for performing separate reception using an unknown information sequence on the receiving side without adding a known preamble. Since an unknown information sequence is used on the receiving side, this processing is called blind processing.

  As a technique for separating and receiving wireless signals from a plurality of users existing on the same frequency channel using a plurality of antennas by blind processing, a technique combining two of arrival direction estimation and adaptive array is known. In Patent Document 1, the direction of arrival is estimated by a MUSIC (Multiple Signal Classification) method, and the adaptive array is controlled based on the obtained direction of arrival, thereby realizing a function of separating an arbitrary signal from a plurality of incoming waves. "Receiving device" is disclosed.

  By the way, the arrival direction estimation described above operates based on a predetermined number of arrival waves. Therefore, in general, arrival direction estimation such as AIC (Akaike Information Criteria) and MDL (Minimum Description Length) is used in combination for the arrival direction estimation. Patent Document 2 discloses a “direction detection device” that combines arrival direction estimation by the MUSIC method and arrival wave number estimation.

  FIG. 5 is a diagram showing a configuration of a receiving apparatus 200 having a function of separating and receiving signals from a plurality of users by blind processing by combining the three techniques of arrival wave number estimation, arrival direction estimation, and adaptive array described above. . The receiving apparatus 200 includes antennas 1_1 to 1_M, radio units 2_1 to 2_M, an eigenvalue analysis circuit 31, an arrival direction estimation circuit 32, an arrival wave number estimation circuit 50, a signal extraction circuit 33, and demodulation circuits 34_1 to 34_M-1. Yes.

In the receiving apparatus 200, the radio signals are received by the antennas 1_1 to 1_M, and the signals received by the radio units 2_1 to 2_M are subjected to frequency conversion and conversion into digital signals. The eigenvalue analysis circuit 31 generates a covariance matrix of the signal converted into a digital signal, performs eigenvalue analysis on the covariance matrix, and calculates an eigenvalue and a corresponding eigenvector. The arrival wave number estimation circuit 50 estimates the arrival wave number from the calculated eigenvalue using a technique such as MDL or AIC. The arrival direction estimation circuit 32 estimates the arrival direction assuming the estimated number of arrival waves based on the calculated eigenvalue and the corresponding eigenvector. The signal extraction circuit 33 extracts signal components corresponding to the estimated arrival directions. Demodulation circuits 34-1 to 34_M-1 reproduce information sequences from the extracted signals, respectively.
Japanese Patent No. 3224591 JP 2002-107440 A

  However, in general, even when the above-described methods such as AIC and MDL are applied, the total number of antenna elements and the number of incoming waves are almost the same, the incoming waves have an angular spread, or there is mutual coupling between the antenna elements. Are prone to errors in estimating the number of incoming waves. If an error occurs in the estimation of the number of arrival waves, the estimation accuracy of the subsequent arrival direction estimation will deteriorate, the arrival direction of the arrival wave that should have existed is not estimated, or the arrival direction of the arrival wave that should not have existed is incorrect. May be estimated. As a result, compared to the case where the same operation is performed with the correct number of incoming waves, the operation of the adaptive array becomes inaccurate, the SINR (Signal to Interference plus Noise Ratio) of the adaptive array output signal is reduced, and the information series is reproduced correctly. The probability that it can be reduced.

  The present invention has been made in view of the above, and an object of the present invention is to provide an adaptive array in which a direction of arrival is estimated using a wrong number of incoming waves as a parameter in a receiving apparatus that separates and receives signals from a plurality of users by blind processing. It is an object of the present invention to provide a receiving apparatus that avoids a decrease in SINR of an output signal and extracts more information sequences.

  In order to solve the above-described problem, the present invention provides a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas, and connects M (M ≧ 2) antennas to the antennas. An information sequence extraction unit having an input terminal, wherein the information sequence extraction unit calculates a reception correlation matrix from a signal input from the input terminal, and calculates an eigenvalue and an eigenvector of the reception correlation matrix And M-1 pieces of directions for estimating the direction of arrival on the basis of the eigenvalues and the eigenvectors calculated by the eigenvalue analysis means and assuming the number of incoming waves of different m waves (1 ≦ m ≦ M−1). Arrival direction estimation means, M-1 signal extraction means for extracting signal components corresponding to the arrival directions estimated by the arrival direction estimation means, and the signal extraction means M × (M−1) / 2 demodulation means for reproducing an information sequence from the signals extracted by each of the stages, and whether or not the information sequence reproduced by each of the demodulation means includes an error. Whether M × (M−1) / 2 error detection means that outputs only information sequences that have been detected and determined to be error-free and information sequences output from each of the error detection means overlap. And a duplicated sequence detecting means for outputting and outputting a non-overlapping information sequence as it is, and selecting and outputting only one information sequence out of the information sequence. It is.

  The present invention provides a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas, and an information sequence extracting means having M (M ≧ 2) antennas and input terminals connected to the antennas. And the information series extracting means calculates an input signal management means for managing a signal input from the input terminal, and calculates a reception correlation matrix from the input signal managed by the input signal management means, Based on the eigenvalue analysis means for calculating the eigenvalues and eigenvectors of the reception correlation matrix, a counter that sequentially counts from 1 to M-1, and the eigenvalue and eigenvector calculated by the eigenvalue analysis means, From the arrival direction estimation means for estimating the arrival direction assuming the number of arrival waves, and the input signal managed by the input signal management means, A signal extraction means for extracting a signal component corresponding to the direction; M-1 demodulation means for reproducing an information sequence from the signal extracted by the signal extraction means; and an information sequence reproduced by each of the demodulation means M-1 error detection means for outputting only information sequences determined to contain no errors, and managing information sequences output from each of the error detection means, When a series of processing from the counter to the error detection means is executed M-1 times, the information series management means for outputting the managed information series and the information series output from the information series management means overlap. And overlapping sequence detection means for selecting and outputting only one information sequence out of the information sequence, and outputting the non-overlapping information sequence as it is. It is a receiver that.

  The present invention relates to a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas, M antennas (M ≧ 2), one input terminal, and first and second two An N-stage (N ≧ 1) signal separation means having an output terminal, wherein the input terminal of the first stage is connected to the antenna, and the first output terminal is connected to the input terminal of the subsequent stage; It is connected to the second output terminal of each of the signal separators connected in multiple stages, and detects whether or not the information series output from the second output terminals of all the signal separators overlap, A redundant information sequence is output as it is, and an overlapping information sequence is selected by outputting only one information sequence out of the information sequence, and an overlapping sequence detection unit is provided, and each of the signal separation units includes the input sequence Input from the terminal A predetermined information series is extracted based on the signal, and the information series extraction means for outputting the extracted information series to the second output terminal, the information series extracted by the information series extraction means and the input terminal Based on the received signal, propagation path information estimation means for estimating propagation path information relating to the information series, based on the information series extracted by the information series extraction means and the propagation path information estimated by the propagation path information estimation means A replica generating means for generating a received signal replica; and a replica subtracting means for subtracting the received signal replica from the signal input from the input terminal and outputting the subtracted signal to the first output terminal. It is a receiver.

The present invention provides a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas, M antennas (M ≧ 2), a first input terminal connected to the antennas, and a second input terminal. Switching means having an input terminal and one output terminal, one input terminal connected to the output terminal of the switching means, a first output terminal connected to the second input terminal of the switching means, and a second A signal separation means having an output terminal, an information series management means connected to a second output terminal of the signal separation circuit, and an overlapping series detection means connected to the information series management means, the switching The means outputs a signal from the antenna only when the signal separation means is in an initial state, and when the signal from the antenna is input to the signal separation means, the first output terminal of the signal separation means thereafter From It outputs a signal, the information sequence management means,
A series of processes from managing the information series output from the second output terminal of the signal separating means, receiving a signal from the input terminal of the signal separating means, and outputting a signal from the second output terminal Is executed for a predetermined number of times, the managed information series is output, and the duplicate series detection means detects whether the information series output from the information series management means overlaps, The non-overlapping information series is output as it is, the overlapping information series selects and outputs only one information series out of the information series, and each of the signal separation means is predetermined based on the signal input from the input terminal. The information series extracting means for extracting the information series and outputting the extracted information series to the second output terminal; the information series extracted by the information series extracting means; and the input from the input terminal Based on the received signal, propagation path information estimation means for estimating propagation path information related to the information series, information series extracted by the information series extraction means, and propagation path information estimated by the propagation path information estimation means A replica generating means for generating a received signal replica; and a replica subtracting means for subtracting the received signal replica from the signal input from the input terminal and outputting the subtracted signal to the first output terminal. It is a receiver.

  According to the present invention, in the above-described invention, the information sequence extraction unit calculates an eigenvalue and an eigenvector of the reception correlation matrix from a signal input from the input terminal, and calculates an eigenvalue and an eigenvector of the reception correlation matrix; Based on the eigenvalue and the eigenvector calculated by the eigenvalue analyzing means, M-1 arrival directions for estimating the arrival direction assuming different arrival wave numbers of m waves (1 ≦ m ≦ M−1) are used. An M-1 signal extraction means for extracting signal components corresponding to the arrival directions estimated by the estimation means and the arrival direction estimation means, and an information sequence from the signals extracted by the signal extraction means. It is determined that there are no errors by detecting M × (M−1) / 2 demodulating means to be reproduced and whether or not the information sequence reproduced by each of the demodulating means contains an error. M × (M−1) / 2 error detection means for outputting only the information series that has been output and whether or not the information series output from the error detection means are duplicated. Second overlapping sequence detection means for outputting to the second output terminal, selecting only one information sequence from among the information sequences as the overlapping information sequence, and outputting to the second output terminal; It is characterized by that.

  According to the present invention, in the above-described invention, the information series extraction unit receives from the input signal management unit that manages the signal input from the input terminal and the input signal that is managed by the input signal management unit. Based on the eigenvalue analyzing means for calculating the correlation matrix and calculating the eigenvalue and eigenvector of the received correlation matrix, the counter for counting from 1 to M-1 in order, the eigenvalue and the eigenvector calculated by the eigenvalue analyzing means An arrival direction estimation means for estimating an arrival direction assuming an output of the counter as an arrival wave number and a signal extraction means for extracting a signal component corresponding to the arrival direction from an input signal managed by the input signal management means M-1 demodulating means for reproducing an information sequence from the signal extracted by the signal extracting means, and each of the demodulating means M-1 error detection means for detecting whether or not the reproduced information sequence includes an error and outputting only the information sequence determined to have no error, and the error detection means output from each of the error detection means Information series management means for managing an information series and outputting a managed information series when a series of processing from the counter to the error detection means is executed M-1 times, and output from the information series management means Whether or not the information series overlap, and the non-overlapping information series is output to the second output terminal as it is, and only one information series is selected as the overlapping information series, and the first And second overlapping sequence detection means for outputting to the second output terminal.

  The present invention is characterized in that, in the invention described above, the signal extraction means performs signal extraction using any one algorithm of MRC, ZF, MMSE, MSN, and DCMP.

  According to the present invention, in the above-described invention, the arrival direction estimation means arrives using any one of the algorithms of MUSIC, Root-MUSIC, ESPRIT, Unitary MUSIC, ESPRIT, Unitary MUSIC, Unitary Root-MUSIC, and Unitary ESPIRT. Direction estimation is performed.

  According to the present invention, in the above-described invention, the signal extraction means connected to the arrival direction estimation means for estimating the arrival direction assuming the number of arrival waves of one wave among the signal extraction means is the eigenvalue analysis means. A signal component corresponding to the first eigenvector obtained in step 1 is extracted.

  According to the present invention, in the above-described invention, the signal extraction unit corresponds to the first eigenvector obtained by the eigenvalue analysis unit when the arrival direction estimation unit operates assuming that the number of arrival waves is one wave. A signal component is extracted.

  According to the present invention, in the invention described above, the signal extraction unit connected to the arrival direction estimation unit that operates assuming that the number of arrival waves is m waves among the signal extraction units is the arrival direction estimation unit. A portion in which m eigenvectors corresponding to the upper m eigenvalues obtained by the eigenvalue analyzing unit span a response vector representing the amplitude ratio and phase difference of each antenna element when a signal enters from the estimated direction of arrival. A signal component corresponding to the response vector after correction is extracted by projecting to a space.

  According to the present invention, in the above-described invention, the signal extraction unit receives signals from m directions corresponding to the arrival directions estimated by the arrival direction estimation unit that operates assuming that the number of arrival waves is m waves. A response vector representing the amplitude ratio and phase difference of each antenna element when incident is projected and corrected to a subspace spanned by m eigenvectors corresponding to the upper m eigenvalues obtained by the eigenvalue analyzing means, A signal component corresponding to the response vector after correction is extracted.

  The present invention is characterized in that, in the above-described invention, when all of the error detection means detect an error, the reception process is terminated.

  The present invention is characterized in that, in the above-described invention, when all of the error detection means detect an error M-1 times consecutively, the reception process is terminated.

  In the present invention described above, the propagation path information estimated by the propagation path information estimation means includes a frequency difference between a local oscillator of the receiving apparatus and a local oscillator of the transmitting apparatus, a clock timing error between the receiving apparatus and the transmitting apparatus, and It is a response vector between the antenna of the transmitting device and the antenna array of the receiving device.

According to this invention, the receiving apparatus includes M (M ≧ 2) antennas and an information sequence extracting unit having an input terminal connected to the antennas. The information series extraction unit calculates a reception correlation matrix from a signal input from the input terminal, and calculates an eigenvalue and an eigenvector of the reception correlation matrix, and an eigenvalue and an eigenvector calculated by the eigenvalue analysis unit Thus, M-1 arrival direction estimation means for estimating the arrival direction assuming different arrival wave numbers of m waves (1 ≦ m ≦ M−1), and arrival directions estimated by the arrival direction estimation means, respectively. M−1 signal extraction means for extracting signal components corresponding to the signal input from the input terminal, and M × (M− 1) / 2 demodulating means, and detecting whether or not an information sequence reproduced by each of the demodulating means contains an error, and outputting only an information sequence determined not to contain an error M × M-1) / 2 It is detected whether or not the information sequences output from each of the error detection means and the error detection means are overlapped, and the non-overlapping information series is output as it is, and the overlapping information series is the information An overlapping sequence detection unit that selects and outputs only one information sequence from the sequence, and for the arrival direction estimation unit that estimates the arrival direction assuming the number of m-wave arrival waves, The m number of demodulating means are connected via the signal extracting means, and one error detecting means is connected to one demodulating means. The number of incoming waves m is not estimated, and the number of incoming waves m is The direction of arrival is estimated for all cases of 1 or more and M-1 or less, and the information sequence reproduced at that time is output as an information sequence obtained when the correct number of incoming waves m is estimated with no error included. , Duplicate information series It was set as the structure which outputs only one of them . As a result, when signals from multiple users were separately received based on the arrival direction estimation, the arrival direction estimation was performed by assuming all the arrival wave numbers that can be estimated, without using the arrival wave number estimation. It is possible to extract signal components corresponding to all arrival directions. By operating in this way, the output from the at least one signal extraction means can avoid a decrease in SINR due to an error in estimation of the number of incoming waves. Further, by performing error detection and overlapped sequence detection on the reproduced information sequence, it is possible to prevent an erroneous information sequence or a plurality of identical information sequences from being output.

Further, according to the present invention, the receiving apparatus includes M (M ≧ 2) antennas and an information sequence extracting unit having an input terminal connected to the antennas. The information series extracting means calculates the reception correlation matrix from the input signal management means for managing the signal inputted from the input terminal, and the input signal managed by the input signal management means, and the eigenvalue and eigenvector of the reception correlation matrix Based on the eigenvalue and eigenvectors calculated by the eigenvalue analyzing means, the eigenvalue analyzing means for calculating the arrival direction, the arrival direction is estimated based on the eigenvalue and eigenvector calculated by the eigenvalue analyzing means. A direction estimation unit, a signal extraction unit that extracts a signal component corresponding to the direction of arrival from an input signal managed by the input signal management unit, and an M- that reproduces an information sequence from the signal extracted by the signal extraction unit Information determined by detecting whether there is an error in one demodulating means and whether the information sequence reproduced by each demodulating means contains an error M-1 error detection means for outputting only the columns, and the information series output from each of the error detection means are managed, and when a series of processing from the counter to the error detection means is executed M-1 times, Information sequence management means for outputting the managed information series and whether or not the information series outputted from the information series management means are duplicated, the non-overlapping information series is outputted as it is, And an overlapping sequence detecting means for selecting and outputting only one information sequence out of the information sequences, without estimating the number of incoming waves m, and for all cases where the number of incoming waves m is 1 or more and M-1 or less. Estimate the information sequence that is reproduced without error and output it as the information sequence obtained when the correct number of incoming waves m is estimated. Only one of the overlapping information sequences Configured to output. As a result, only one set of arrival direction estimation means, signal extraction means, demodulation means, and error detection means that operates using the number of incoming waves as a parameter is prepared. By reusing these circuits, it is possible to reduce the circuit scale without reducing the information sequence extraction capability.

  Further, according to the present invention, the signal extraction means according to the receiving apparatus can perform signal extraction using any one algorithm of MRC, ZF, MMSE, MSN, and DCMP.

  Also, according to the present invention, the arrival direction estimation means for the receiving device arrives using any of the algorithms of MUSIC, Root-MUSIC, ESPRIT, Unitary MUSIC, ESPRIT, Unitary MUSIC, Unitary Root-MUSIC, and Unitary ESPIRT. Direction estimation can be performed.

  Further, according to the present invention, the signal extraction means connected to the arrival direction estimation means for estimating the arrival direction assuming the number of arrival waves of one wave among the signal extraction means for the receiving device is an eigenvalue analysis means. The signal component corresponding to the obtained first eigenvector is extracted. Thereby, the arrival estimation means for estimating the arrival direction assuming the number of arrival waves of one wave can be omitted, and the circuit scale can be reduced. In addition, with the above configuration, it is possible to avoid deterioration in the accuracy of response vector estimation when the incoming wave has an angular spread.

Further, according to the present invention, the signal extraction means according to the receiving device, when the arrival direction estimation means operates assuming that the number of arrival waves is 1, the signal component corresponding to the first eigenvector obtained by the eigenvalue analysis means It was set as the structure which extracts. As a result, when the number of incoming waves is one, the first eigenvector e ₁ itself becomes a response vector. Therefore, when the signal extraction unit extracts a signal component corresponding to the first eigenvector, the incoming wave has an angular spread. It is possible to reduce a decrease in SINR of a signal after extraction due to deterioration in estimation accuracy of the response vector.

  According to the present invention, the signal extraction means connected to the arrival direction estimation means that operates assuming that the number of incoming waves is m waves among the signal extraction means according to the receiving apparatus is estimated by the arrival direction estimation means. The response vector representing the amplitude ratio and phase difference of each antenna element when a signal enters from the direction of arrival is projected onto a subspace spanned by m eigenvectors corresponding to the upper m eigenvalues obtained by the eigenvalue analysis means. The signal component corresponding to the response vector after correction is extracted. As a result, the correct response vectors for each arriving wave are all present in the signal subspace. By projecting the response vector corresponding to the estimated direction of arrival to the signal subspace, the arrival wave has an angular spread. It is possible to reduce a decrease in SINR of a signal after extraction due to deterioration of response vector estimation accuracy.

  Further, according to the present invention, the signal extraction means according to the receiving apparatus receives signals from m directions corresponding to the arrival directions estimated by the arrival direction estimation means that operates assuming that the number of arrival waves is m waves. The response vector representing the amplitude ratio and phase difference of each antenna element is corrected by projecting to the subspace spanned by the m eigenvectors corresponding to the upper m eigenvalues obtained by the eigenvalue analysis means, and after the correction The signal component corresponding to the response vector is extracted. As a result, the correct response vectors for each arriving wave are all present in the signal subspace. By projecting the response vector corresponding to the estimated direction of arrival to the signal subspace, the arrival wave has an angular spread. It is possible to reduce a decrease in SINR of a signal after extraction due to deterioration of response vector estimation accuracy.

Hereinafter, first to fourth embodiments according to the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram illustrating a functional configuration of the receiving apparatus 101 according to the first embodiment. As shown in FIG. 1, the receiving apparatus 101 includes antennas 1_1 to 1_M, radio units 2_1 to 2_M, and an information series extraction circuit 3a. The information series extraction circuit 3a includes an eigenvalue analysis circuit 31, arrival direction estimation circuits 32_1 to 32_M-1, signal extraction circuits 33_1 to 33_M-1, demodulation circuits 34_1_1 to 34_M-1_M-1, and error detection circuits 35_1_1 to 35_M-. 1_M−1 and an overlapping sequence detection circuit 36a.

  Next, the operation of the receiving apparatus 101 according to the first embodiment will be described with reference to FIG. The receiving apparatus 101 receives radio signals by the antennas 1_1 to 1_M, and performs frequency conversion and conversion to digital signals on the signals received by the radio units 2_1 to 2_M. The information series extraction circuit 3a extracts an information series included in the signal converted into a digital signal by the radio units 2_1 to 2_M.

  Next, the operation of each circuit provided in the information series extraction circuit 3a of the first embodiment will be described. The eigenvalue analysis circuit 31 generates a covariance matrix of signals input from the input terminals connected to the radio units 2_1 to 2_M, performs eigenvalue analysis on the covariance matrix, and calculates eigenvalues and corresponding eigenvectors. The arrival direction estimation circuits 32_1 to 32_M−1 perform arrival direction estimation assuming the number of arrival waves of 1 to M−1 waves based on the calculated eigenvalues and corresponding eigenvectors. The signal extraction circuits 33_1 to 33_M-1 extract signal components corresponding to the arrival directions estimated by the arrival direction estimation circuits 32_1 to 32_M-1. The demodulating circuits 34_1_1 to 34_M-1_M-1 reproduce information sequences from the signals extracted by the signal extracting circuits 33_1 to 33_M-1. The error detection circuits 35_1_1 to 35_M-1_M-1 detect whether or not there is an error in the information sequence reproduced using, for example, CRC (Cyclic Redundancy Check), and output only the information sequence with no error. The duplicate sequence detection circuit 36a detects, for example, whether there is a duplicate sequence in an error-free information sequence using, for example, all-bit coincidence detection between information sequences, and outputs a non-overlapping sequence as it is. Only one of them will be output.

Next, the detailed operation of the eigenvalue analysis circuit 31 will be described. First, from the digital signals y ₁ (t) to y _M (t) from the radio units 2_1 to 2_4, a covariance matrix R _yy is calculated as in the following equation (1).

Here, the subscript H represents a conjugate transposition, and E [] represents an average operation. Then, eigenvalues λ _{1 to} λ _M satisfying the following expression (2) and corresponding eigen vectors e ₁ to e _M are obtained from the covariance matrix R _yy .

  Next, a detailed operation of the arrival direction estimation circuit 32_2 will be described. The arrival direction estimation circuit 32_2 operates assuming that the number of arrival waves is two. In the following description, it is assumed that the MUSIC method is used for the arrival direction estimation algorithm. However, as indicated in the appended claims, the arrival direction estimation algorithm includes ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) in addition to the MUSIC method. ) Method, Root-MUSIC method, Unitary MUSIC method, Unitary ESPRIT method, and Unitary Root-MUSIC method.

The MUSIC method uses a subspace spanned by noise eigenvectors (eigenvectors corresponding to eigenvalues equal to or lower than 3 when the incoming wave is assumed to be 2 waves) and response vectors of each user (complex impulse responses between transmission antennas and reception antennas). The direction of arrival is estimated using the fact that the inner product of becomes zero. Specifically, θ ₁ and θ ₂ indicating the two peaks of the evaluation function f (θ) represented by the following equation (3) are defined as directions of arrival.

  Here, a (θ) represents a response vector when a plane wave is incident from an angle θ. The direction of arrival estimation circuits other than the direction of arrival estimation circuit 32_2 are the same as the direction of arrival estimation circuit 32_2 except that the number of incoming waves is different.

Next, detailed operation of the signal extraction circuit 33_2 will be described. The signal extraction circuit 33_2 obtains weights w ₁ and w ₂ based on the response vectors a (θ ₁ ) and a (θ ₂ ) corresponding to the two arrival directions estimated by the arrival direction estimation circuit 32_2, and uses these weights. The received signal components corresponding to the response vectors a (θ ₁ ) and a (θ ₂ ) are extracted. In the following description, the ZF (Zero Forcing) method is used as the adaptive array weight calculation algorithm. However, as shown in the appended claims, the weight calculation algorithm includes an MRC (Maximum Ratio) in addition to the ZF method. Combining method, MMSE (Minimum Mean Squared error) method, MSN (Maximum Signal-to-Noise ratio) method, DCMP (Directionally Constrained Minimization of Power) method can be used.

In the ZF method, the vector having the highest inner product with the response vector of the desired user among the vectors that make the inner product with the response vector of the user that causes interference zero is used as the weight. Specifically, the weights w ₁ and w ₂ are calculated from the following equation (4).

Using the w1 and w2 obtained in this way, the adaptive array is operated as shown in the following equation (5), and the received signals y ₁ (t) to y ₄ (t) correspond to θ ₁ and θ ₂ . The signal components z ₁ (t) and z ₂ (t) are extracted.

  The signal extraction circuits other than the signal extraction circuit 33_2 are the same as the signal extraction circuit 33_2 except that the number of response vectors used (input) is different.

  As described above in detail, in the first embodiment, when signals from a plurality of users are separately received based on direction-of-arrival estimation, all the number of arrival waves that can be estimated in the direction of arrival are assumed without using arrival-wave number estimation. The direction of arrival is estimated and signal components corresponding to all the directions of arrival obtained are extracted. By operating in this way, the output from the at least one signal extraction circuit can avoid a decrease in SINR due to an error in the estimation of the number of incoming waves.

However, as mentioned above, if direction of arrival estimation is performed assuming the wrong number of incoming waves, the direction of arrival that should have existed may not be estimated, or the direction of arrival that should not have existed may be estimated incorrectly. In the first embodiment, which operates assuming all the number of arrival waves for which the arrival direction can be estimated, an erroneous information sequence is often reproduced. Even if direction of arrival estimation is performed assuming an incorrect number of incoming waves, an error-free information sequence can be reproduced as long as the SINR after signal extraction is equal to or greater than a certain value. There is sex.
Therefore, in the first embodiment of the present invention, error detection and overlapped sequence detection are performed on the reproduced information sequence to prevent an erroneous information sequence or a plurality of identical information sequences from being output.

(Second embodiment)
FIG. 2 is a block diagram illustrating a functional configuration of the receiving apparatus 102 according to the second embodiment. As illustrated in FIG. 2, the reception device 102 includes antennas 1_1 to 1_M, radio units 2_1 to 2_M, and an information sequence extraction circuit 3b. The information series extraction circuit 3b includes an input signal management circuit 37, an eigenvalue analysis circuit 31, a counter 38, an arrival direction estimation circuit 32, a signal extraction circuit 33, demodulation circuits 34_1 to 34_M-1, and error detection circuits 35_1 to 35_M-1. , The information series management circuit 39 and the duplicate series detection circuit 36b.

  Next, the operation of the second embodiment will be described. In the receiving apparatus according to the second embodiment, the radio signals are received by the antennas 1_1 to 1_M, and the signals received by the radio units 2_1 to 2_M are converted into frequencies and digital signals. The information series extraction circuit 3b extracts an information series included in the signal converted into a digital signal.

  Next, the operation of each circuit constituting the information series extraction circuit 3b of the second embodiment will be described. The input signal management circuit 37 manages the input signal and supplies it to the eigenvalue analysis circuit 31 and the signal extraction circuit 33. The eigenvalue analysis circuit 31 generates a covariance matrix of the input signal, performs eigenvalue analysis on the covariance matrix, and calculates eigenvalues and corresponding eigenvectors. The counter 38 counts up from 1 to M-1 and outputs the value. Based on the calculated eigenvalue and the corresponding eigenvector, the arrival direction estimation circuit 32 estimates the arrival direction assuming that the counter output value (change from 1 to M−1) is the number of arrival waves. The signal extraction circuit 33 extracts a signal component corresponding to the estimated arrival direction. In the demodulation circuits 34_1 to 34_M-1, the information series is reproduced from the extracted signal M-1 times. The error detection circuits 35_1 to 35_M−1 detect whether or not there is an error in the information sequence reproduced using, for example, CRC, and output only the information sequence without error and store it in the information sequence management circuit 39. A series of operations from the counter 38 to the error detection circuits 35_1 to 35_M−1 is performed M−1 times, and then an information sequence stored in the information sequence management circuit 39 is output. The overlapping sequence detection circuit 36b detects whether there are overlapping sequences among the information sequences stored in the information sequence management circuit 39 by using, for example, all-bit coincidence detection between the information sequences. Is output as it is, and only one of the overlapping sequences is output. Detailed operations of the eigenvalue analysis circuit 31, the arrival direction estimation circuit 32, and the signal extraction circuit 33 are as follows. The eigenvalue analysis circuit 31, the arrival direction estimation circuits 32_1 to 32_M-1, and the signal extraction circuits 33_1 to 33_M-1 according to the first embodiment. Is the same.

  As described above, in the second embodiment, only one set of arrival direction estimation circuit 32, signal extraction circuit 33, demodulation circuits 34_1 to 34_M-1, and error detection circuits 35_1 to 35_M-1 operating with the number of incoming waves as parameters is prepared. Then, by providing parameters, that is, the number of incoming waves from 1 to M-1 in order by a counter and reusing these circuits, the circuit scale can be reduced without reducing the information sequence extraction capability as compared with the first embodiment. .

(Third embodiment)
FIG. 3 is a block diagram illustrating a functional configuration of the receiving apparatus 103 according to the third embodiment. As illustrated in FIG. 3, the reception device 103 includes antennas 1_1 to 1_M, radio units 2_1 to 2_M, signal separation circuits 41_1 to 41_N, and an overlapping sequence detection circuit 5. The signal separation circuits 41_1 to 41_N all have the same configuration. For example, each of the signal separation circuits 41_1 is the same as the information series extraction circuit 3a shown in FIG. 1 or the information series extraction circuit 3b shown in FIG. The configuration includes an information series extraction circuit 411_1, a propagation path information estimation circuit 412_1, a replica generation circuit 413_1, and a replica subtraction circuit 414_1.

  Next, the operation of the third embodiment will be described. In the receiving apparatus of the third embodiment, radio signals are received by the antennas 1_1 to 1_M, and frequency conversion and conversion to digital signals are performed on the signals received by the radio units 2_1 to 2_M. In the signal separation circuits 41_1 to 41_N having the first and second output terminals (the output terminal 1 and the output terminal 2 in FIG. 3), extraction of the information series included in the input signal and the information from the input signal Cancels the received signal replica of the sequence. In the overlapping sequence detection circuit 5, for example, it is detected whether there is an overlapping sequence among the information sequences extracted by the signal separation circuit using, for example, all-bit coincidence detection between information sequences, and the non-overlapping sequence is output as it is. Only one of the overlapping sequences is output.

  Next, the operation of each circuit constituting the signal separation circuits 41_1 to 41_N of the third embodiment will be described. Since all of the signal separation circuits 41_1 to 41_N perform the same operation, only the operation of the signal separation circuit 41_1 will be described below. In the information series extraction circuit 411_1, the information series extraction circuit 3a shown in FIG. 1 or the information series extraction circuit 3b shown in FIG. 2 is applied to extract the information series included in the input signal and to output the second output terminal. Output from. The propagation path information estimation circuit 412_1 estimates propagation path information corresponding to the information series extracted by the information series extraction circuit 411_1. The replica generation circuit 413_1 generates a received signal replica based on the information sequence extracted by the information sequence extraction circuit 411_1 and the propagation path information estimated by the propagation path information estimation circuit 412_1. The replica subtraction circuit 414_1 subtracts the reception signal replica generated by the replica generation circuit 413_1 from the input signal and outputs the result to the first output terminal.

Next, detailed operation of the propagation path information estimation circuit 412_1 will be described. In the following description, it is assumed that K information sequences x _k (t) have been extracted by the information sequence extraction circuit 411_1. The propagation path information estimation circuit 412_1 has a frequency difference Δf _k between the local oscillator of the receiving apparatus and the local oscillator of the transmitting apparatus corresponding to each information series based on the information series x _k (t) extracted by the information series extraction circuit 411_1. The clock timing error Δt _k between the transmitting device and the receiving device and the response vector h _k between the antenna of the transmitting device and the antenna array of the receiving device are estimated. Below, an example of the estimation method of the three propagation path information mentioned above is demonstrated, However, An estimation method is not limited to this. First, Δt that maximizes the evaluation function g _k (Δt) of the following equation (6) is defined as Δt _k .

Here, T is the symbol length, and _NT is the number of symbols in one frame. After determining Δt _k , Δf _k is estimated from the following equation (7).

Finally, the response vector h _k is estimated by the following equation (8).

Next, a detailed operation of the replica generation device 413_1 will be described. In the replica generation circuit 413_1, the information sequence x _k (t) extracted by the information sequence extraction circuit 411_1 and the frequency difference Δf _k corresponding to x _k (t) estimated by the propagation path information estimation circuit 412_1, the clock timing error Δt _A received signal replica y _k (t) is generated by the following equation (9) using _k and response vector h _k .

Next, detailed operation of the replica subtraction circuit 414_1 will be described. The replica subtraction circuit 414_1 subtracts K reception signal replicas y _k (t) obtained by the replica generation circuit 413_1 from the reception signal y ⁽¹⁾ (t) as shown in the following equation (10), and the result is The signal is output to the subsequent signal separation circuit 41_2.

Here, y ⁽ⁿ⁾ (t) is an input signal of the signal separation circuit 41 — ⁿ .

  As described in detail above, the signal separation circuit 41_1 extracts an information sequence from the input signal, subtracts the received signal replica of the extracted information sequence, and cancels the extracted information sequence component. In the subsequent signal separation circuit 41_2, since the signal from which the components of the information series already extracted by the signal separation circuit 41_1 are canceled is used as an input signal, an information series that cannot be extracted by the signal separation circuit 41_1 can be extracted. The possibility increases. As described above, by arranging a plurality of signal separation circuits and continuously performing the above-described operation, it is possible to extract more information series as compared with the first and second embodiments.

(Fourth embodiment)
FIG. 4 is a block diagram illustrating a functional configuration of the receiving device 104 according to the fourth embodiment. As illustrated in FIG. 4, the reception device 104 includes a signal separation circuit having antennas 1_1 to 1_M, radio units 2_1 to 2_M, and first and second output terminals (output terminal 1 and output terminal 2 in FIG. 4). 4, an overlapping sequence detection circuit 5, a switching circuit 6, and an information sequence management circuit 7. Next, the operation of the fourth embodiment will be described. In the receiving apparatus according to the fourth embodiment, the radio signals are received by the antennas 1_1 to 1_M, and the signals received by the radio units 2_1 to 2_M are converted into frequencies and digital signals. In the signal separation circuit 4, as in the signal separation circuits 4_1 to 4_N shown in FIG. 3, the information series included in the input signal is extracted and the received signal replica of the information series from the input signal is canceled. The switching circuit 6 outputs signals from the radio units 2_1 to 2_M only when the signal separation circuit 4 is in an initial state, and once the signals from the radio units 2_1 to 2_M are input to the signal separation circuit 4, the switching circuit 6 thereafter A signal input from the first output terminal of the signal separation circuit 4 is output. The information series management circuit 7 manages the information series extracted by the signal separation circuit 4, and when a series of processing from the input terminal of the signal separation circuit 4 to the second output terminal is executed a predetermined number of times, Output managed information series. The duplicate sequence detection circuit 5 detects whether or not there is a duplicate sequence among the information sequences output from the information sequence management circuit 7 using, for example, all-bit coincidence detection between information sequences. The data is output as it is, and only one of the overlapping sequences is output.

  As described above, in the fourth embodiment, the input terminal and the first output terminal of the signal separation circuit 4 are looped through the switching circuit 6, and the single signal separation circuit 4 is reused, so that the third Compared to the embodiment, the circuit scale can be reduced without reducing the information sequence extraction capability.

  Next, modifications of the receiving device according to the first to fourth embodiments will be described.

(Modification 1)
In the first modification, the arrival direction estimation circuit 32_1 shown in FIG. 1 is omitted in the first, third, and fourth embodiments, and the signal extraction circuit 33_1 uses the first eigenvector obtained by the eigenvalue analysis circuit 31 as a response vector. the e ₁ is used.

  Direction-of-arrival estimation operates assuming that the same signal does not come from multiple directions (one signal comes from only one direction), and the response vector corresponding to the estimated direction of arrival is assumed to be similar Therefore, when the incoming wave has an angular spread (the same signal arrives from a plurality of directions), the estimation accuracy of the arrival direction deteriorates, and finally the signal extraction circuits 33_1 to 33_M− Therefore, the estimation accuracy of the response vector of the incoming wave required in 1 is deteriorated.

By the way, as described above, all the correct response vectors of the incoming waves exist in the signal subspace. In other words, when the number of incoming waves is one, the first eigenvector e ₁ itself becomes a response vector. Therefore, by extracting the signal component corresponding to the first eigenvector e ₁ in the signal extraction circuit 33_1, the angle spread of the incoming wave is increased. It is possible to reduce a decrease in SINR of a signal after extraction due to a deterioration in estimation accuracy of a response vector at a certain time. Furthermore, the circuit scale can be reduced by omitting the arrival direction estimation circuit 32_1.

(Modification 2)
In the second modification, in the second to fourth embodiments, when the arrival direction estimation circuit 32 operates assuming that the number of arrival waves is one wave, the signal extraction circuit 33 is obtained by the eigenvalue analysis circuit 31 as a response vector. One eigenvector e ₁ is used. As described above, the subspace spanned by the noise eigenvector and the response vector of each incoming wave are always orthogonal. That is, all correct response vectors for each incoming wave exist in the signal subspace. Therefore, when the number of incoming waves is one, the first eigenvector e ₁ itself becomes a response vector. Therefore, by extracting the signal component corresponding to the first eigenvector e ₁ in the signal extraction circuit 33, the angle spread of the incoming wave is increased. It is possible to reduce a decrease in SINR of a signal after extraction due to a deterioration in estimation accuracy of a response vector at a certain time.

(Modification 3)
In Modification 3, in the first to fourth embodiments, the signal extraction circuit 33_m (1 ≦ m ≦ M−1) or the signal extraction circuit 33 is the arrival direction estimation circuit 32_m (1 ≦ m ≦ M−1) or arrival. The m response vectors a (θ _k ) (k = 1... M) when a signal enters from the direction of arrival estimated by the direction estimation circuit 32 are converted into the upper m eigenvalues obtained by the eigenvalue analysis circuit 31. A signal corresponding to the response vector a ′ (θ _k ) (k = 1... M) after correction is corrected by projecting to a subspace (hereinafter, signal subspace) spanned by the corresponding m eigenvectors. Extract ingredients. The corrected response vector a ′ (θ _k ) (k = 1... M) is calculated as in the following equation (11).

  As described above, when the incoming wave has an angular spread, the estimation accuracy of the response vector of the incoming wave deteriorates, and therefore the estimated response vector does not exist in the signal subspace. However, as described above, since the correct response vector of each incoming wave exists in the signal subspace, by projecting the response vector corresponding to the estimated arrival direction to the signal subspace, the angular spread of the incoming wave is increased. It is possible to reduce a decrease in SINR of a signal after extraction due to a deterioration in estimation accuracy of a response vector at a certain time.

(Modification 4)
In Modification 4, when the information sequence extraction circuit 3a shown in FIG. 1 is applied in the third and fourth embodiments, the reception process is performed when errors are detected in all of the error detection circuits 35_1_1 to 35_1_M-1_M-1. Exit.

  When an error is detected in all of the error detection circuits 35_1_1 to 35_1_M-1_M-1 included in the information sequence extraction circuit 411_1 illustrated in FIG. 3, no signal is output from the information sequence extraction circuit 411_1. Then, since subtraction of replicas is not performed, the input signal of the signal separation circuit 41_1 matches the input signal of the signal separation circuit 41_2. Since the signal separation circuit 41_2 performs the same operation with the same configuration as the signal separation circuit 41_1, even if the signal separation circuits 41_2 to 41_N are operated, no information series is extracted in the same manner. Similarly, in the signal separation circuit 4 shown in FIG. 4, the operation is continued even though errors are detected in all of the error detection circuits 35_1_1 to 35_1_M-1_M-1 constituting the information sequence extraction circuit provided therein. However, no further information series is extracted.

  As described above, even if an error is detected in all of the error detection circuits 35_1_1 to 35_1_M-1_M-1, even if the operation is continued, no further information series is extracted. By terminating the processing, useless processing can be omitted without reducing the ability to extract the information series.

(Modification 5)
In the fifth modification, in the third and fourth embodiments, the reception process ends when errors are detected M-1 times consecutively in all of the error detection circuits 35_1 to 35_M-1 shown in FIG. If an error is detected M-1 times consecutively in all of the error detection circuits 35_1 to 35_M-1, no information sequence is output from the information sequence extraction circuit. Even if the processing is continued, no further information series is extracted. Therefore, by ending the reception process at that time, it is possible to omit useless processing without reducing the ability to extract the information series.

  With the configuration of the above-described embodiment, the receiving apparatus can increase the number of information sequences to be extracted when performing separate reception by blind processing, as compared to the case where arrival wave number estimation is used in combination. Further, by combining with a multistage interference canceller, the number of information sequences to be extracted can be further increased.

  The above receiving apparatus has a computer system inside. The reception process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

It is a block diagram which shows roughly the structure of the receiver which concerns on 1st Embodiment of this invention. It is a block diagram which shows roughly the structure of the receiver which concerns on 2nd Embodiment of this invention. It is a block diagram which shows roughly the structure of the receiver which concerns on 3rd Embodiment of this invention. It is a block diagram which shows roughly the structure of the receiver which concerns on 4th Embodiment of this invention. It is a block diagram which shows schematically the structure of the conventional receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1_1, 1_M Antenna 2_1, 2_M Radio | wireless part 3a Information series extraction circuit 31 Eigenvalue analysis circuit 32_1 ... 32_M-1 Arrival direction estimation circuit 33_1 ... 33_M-1 Signal extraction circuit 34_1_1 ... 34_M-1_M-1 Demodulation circuit 35_1_1 ... 35_M-1_M- 1 Error Detection Circuit 36a Duplicate Sequence Detection Circuit 101 Receiver

Claims (8)

In a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas,
M antennas (M ≧ 2),
An information series extraction means having an input terminal connected to the antenna,
The information series extracting means includes
Eigenvalue analysis means for calculating a reception correlation matrix from a signal input from the input terminal and calculating an eigenvalue and an eigenvector of the reception correlation matrix;
Based on the eigenvalue and the eigenvector calculated by the eigenvalue analysis means, M-1 arrival direction estimations for estimating the arrival direction assuming different arrival wave numbers of m waves (1 ≦ m ≦ M−1). Means,
M-1 signal extraction means for extracting a signal component corresponding to the arrival direction estimated by each of the arrival direction estimation means from a signal input from the input terminal ;
M × (M−1) / 2 demodulation means for reproducing an information sequence from the signals extracted by each of the signal extraction means;
M × (M−1) / 2 error detecting means for detecting whether or not the information series reproduced by each of the demodulating means includes an error and outputting only the information series determined to have no error When,
Detecting whether or not the information series output from each of the error detection means is duplicated, outputting the non-overlapping information series as it is, and selecting only one information series among the information series as the duplicated information series; Output duplicate series detection means;
Equipped with a,
The arrival direction estimation means for estimating the arrival direction assuming the number of arrival waves of m waves is connected to the m demodulation means via one signal extraction means,
One error detection means is connected to one demodulation means,
The arrival wave number m is not estimated, and the arrival direction is estimated for all cases where the arrival wave number m is 1 or more and M−1 or less. A receiving apparatus that outputs as an information sequence obtained when m is estimated, and outputs only one of the overlapping information sequences . In a receiving apparatus capable of receiving signals from a plurality of users using a plurality of antennas,
Comprising M (M ≧ 2) antennas and an information sequence extracting means having an input terminal connected to the antennas,
The information series extracting means includes
Input signal management means for managing a signal input from the input terminal;
Eigenvalue analysis means for calculating a reception correlation matrix from the input signal managed by the input signal management means, and calculating eigenvalues and eigenvectors of the reception correlation matrix;
A counter that sequentially counts from 1 to M-1,
Based on the eigenvalue and the eigenvector calculated by the eigenvalue analysis means, the direction of arrival estimation means for estimating the arrival direction assuming the output of the counter as the number of incoming waves;
Signal extraction means for extracting a signal component corresponding to the direction of arrival from the input signal managed by the input signal management means;
M-1 demodulation means for reproducing an information sequence from the signal extracted by the signal extraction means;
M-1 error detection means for detecting whether or not the information sequence reproduced by each of the demodulation means includes an error, and outputting only the information sequence determined to have no error;
Information series management means for managing information series output from each of the error detection means and outputting a managed information series when a series of processing from the counter to the error detection means is executed M-1 times. When,
It is detected whether or not the information series output from the information series management means overlaps, and the non-overlapping information series is output as it is, and the overlapping information series selects and outputs only one information series of the information series Duplicate sequence detection means;
Equipped with a,
The arrival wave number m is not estimated, and the arrival direction is estimated for all cases where the arrival wave number m is 1 or more and M−1 or less. A receiving apparatus that outputs as an information sequence obtained when m is estimated, and outputs only one of the overlapping information sequences . The signal extraction means includes
3. The receiving apparatus according to claim 1, wherein signal extraction is performed using any one algorithm of MRC, ZF, MMSE, MSN, and DCMP. The arrival direction estimating means includes:
MUSIC, Root-MUSIC, ESPRIT, Unitary MUSIC, ESPRIT, Unitary MUSIC, Unitary Root-MUSIC, to claim 1 or 2, characterized in that the DOA estimation using any algorithm Unitary ESPIRT The receiving device described. Of the signal extraction means, the signal extraction means connected to the arrival direction estimation means for estimating the arrival direction assuming the number of arrival waves of one wave,
2. The receiving apparatus according to claim 1 , wherein a signal component corresponding to the first eigenvector obtained by the eigenvalue analyzing unit is extracted. The signal extraction means includes
3. The reception according to claim 2 , wherein when the arrival direction estimation unit operates assuming that the number of arrival waves is one wave, a signal component corresponding to the first eigenvector obtained by the eigenvalue analysis unit is extracted. apparatus. Of the signal extraction means, the signal extraction means connected to the arrival direction estimation means that operates assuming that the number of incoming waves is m waves,
A response vector representing the amplitude ratio and phase difference of each antenna element when a signal is incident from the direction of arrival estimated by the direction-of-arrival estimation means is represented by m corresponding to the top m eigenvalues obtained by the eigenvalue analysis means. The receiving apparatus according to claim 1 , wherein the signal component corresponding to the corrected response vector is extracted by projecting and correcting the partial space spanned by the eigenvectors. The signal extraction means includes
A response vector representing the amplitude ratio and phase difference of each antenna element when signals are incident from m directions corresponding to the arrival directions estimated by the arrival direction estimation means operating assuming that the number of arrival waves is m waves. Is corrected by projecting onto a partial space spanned by m eigenvectors corresponding to the top m eigenvalues obtained by the eigenvalue analyzing means, and a signal component corresponding to the corrected response vector is extracted. The receiving device according to claim 2 .

Images