JP2006345429A - Receiver associated with digital communication/broadcast, reception method, reception circuit, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a mobile object to attain a stable reception by minimizing deterioration in the quality of a received signal at a virtual reception point even when deterioration is caused in a reception characteristic of an antenna among a plurality of reception antennas. <P>SOLUTION: The receiver for generating a received signal (hereinafter called a virtual reception signal a) at a point relatively fixed with respect to ground by moving a receiving point (hereinafter called a virtual receiving point P) at a speed of -v (just reverse in a moving direction) with respect to a moving speed v is configured such that the receiver selects an antenna in use in response to a reception characteristic of a signal in the case of generating the virtual reception signal a. Even when deterioration of a reception characteristic is caused in received signals of some antennas, the deterioration in the reception characteristic of the virtual reception signal a can thereby be minimized and a high speed mobile body can attain stable and excellent reception. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a receiving apparatus for receiving digital communication / broadcasting in a moving body that moves at high speed.

  At present, orthogonal frequency division multiplexing (OFDM) is widely adopted as a transmission method in various digital communications such as terrestrial digital broadcasting and IEEE802.11a. OFDM is a transmission system that is frequency-multiplexed with a plurality of narrowband digitally modulated signals by subcarriers orthogonal to each other, and is excellent in frequency utilization efficiency. Further, in OFDM, one symbol period is composed of an effective symbol period and a guard interval period, and a part of the signal of the effective symbol period is copied to the guard interval period in order to have periodicity within the symbol. Therefore, it is possible to reduce the influence of inter-symbol interference caused by multipath interference, and it has excellent resistance against multipath interference.

  On the other hand, OFDM has a length of one symbol longer than that of a wideband digital modulation signal, and therefore is less resistant to time fluctuations in a channel fading environment that occurs in mobile reception or the like. Further, under a fading environment, not only the time variation of the amplitude of the received signal due to delay dispersion due to multipath interference, but also a frequency variation called Doppler shift occurs. Due to this Doppler shift, the orthogonal relationship between the individual subcarriers is broken, causing mutual interference, and as a result, it becomes difficult to correctly demodulate. Interfering subcarriers with each other is called ICI (Inter-Carrier Interference), and in mobile communication, suppressing deterioration of communication quality due to ICI is a key.

In recent years, several methods have been proposed as means for reducing deterioration due to ICI. As one of them, there is a method of suppressing ICI by controlling an antenna as in Patent Document 1 shown below.
20 shows the arrangement of antennas attached to a mobile unit described in Patent Document 1, FIG. 21 shows the configuration of a transmitting / receiving device of a mobile unit, and FIG. 22 shows the configuration of the transmitting / receiving unit of a base station. Indicates.

  21 includes K antennas 221 to 22K, a modulation unit 201, a modulation parameter control unit 202, an instantaneous fading estimation unit 203, a demodulation unit 204, a modulation parameter estimation unit 211, switching units 205 and 206, 207, a received signal estimation unit 210. Further, the received signal estimation unit 210 includes an interpolation calculation unit 208 and a movement distance estimation unit 209.

As shown in FIG. 20, the K antennas 221 to 22K are arranged on a straight line along the traveling direction in the casing of the moving body. The distance between adjacent antennas is d (m), and the distance from the first antenna to the last antenna is (K-1) · d (m).
The interpolation estimation unit 208 performs a predetermined interpolation operation on the received signals S221 to S22K received via the antennas 211 to 21K, so that the moving direction of the moving object is reversed from the leading antenna 211. A received signal received at a point P separated by x in the direction is estimated. This distance x is calculated by the movement distance estimation unit 209. The movement distance estimation unit 209 receives a signal indicating the speed V at which the moving body moves, calculates a distance x using Equation 1 from this signal and the elapsed time t from the reference time t0, and outputs the distance x to the interpolation calculation unit 208. To do.

  Since the reception point at this distance x moves at a speed V in the direction opposite to the traveling direction of the moving body, the relative speed is zero, that is, fixed with respect to the ground. Therefore, by estimating the reception signal at a fixed reception point, the estimated reception signal can be regarded as a signal received with the moving body stopped, and a reception signal that compensates for fading fluctuation can be obtained. it can.

  The received signal compensated for fading fluctuation obtained by the interpolation calculation unit 208 is input to the modulation parameter estimation unit 211, and the modulation parameter estimation unit 211 estimates the modulation parameter of the signal transmitted from the base station. The demodulator 204 demodulates the signal obtained by the interpolation calculator 208 according to the estimated modulation parameter, and as a result, demodulated data is generated.

22 includes a modulation parameter estimation unit 241, a demodulation unit 242, an instantaneous fading estimation unit 243, a modulation parameter control unit 244, a modulation unit 245, and a switching unit 246.
FIG. 23 shows the timing of communication between the mobile unit and the base station, and the ground positions (relative positions with respect to the ground) of the antennas 221 and 22K.

  At timing 251 shown in FIG. 23, a signal (pilot tone signal) for measuring the propagation characteristics of the transmission path and the measurement (pilot tone signal) is transmitted from the mobile unit to the base station. The base station receives the pilot tone signal transmitted from the mobile unit, and the instantaneous fading estimation unit 243 estimates the propagation characteristics of the propagation path. The modulation parameter control unit 244 selects the parameter having the highest transmission rate among the modulation parameters satisfying the required transmission quality under the estimated transmission characteristics, and the modulation unit 245 modulates the transmission data. The modulated data is transmitted from the base station to the mobile unit in the interval 252 in FIG.

  In the section 252 in FIG. 23, the mobile unit can perform the above-described interpolation processing, whereby the fading fluctuation received by the transmitted signal in the section 252 can be regarded as constant, and good reception is possible. . At this time, in the movement distance estimation unit 209, the reference time t0 is the timing of 251 and is the time when the pilot tone signal is transmitted from the mobile unit to the base station.

Next, a pilot tone signal for measuring the propagation characteristic of the transmission path is transmitted from the base station to the mobile unit in the timing section 253 in FIG. Even in the section 253, fading fluctuation is made constant by interpolation processing.
In such a series of transmissions and receptions, the receiving side in the mobile body performs interpolation processing to make the fading fluctuation received by the signal constant and enable good reception.

Furthermore, the following Non-Patent Document 1 is a configuration for generating and demodulating a received signal stationary with respect to the ground, as in Patent Document 1, and an interpolation operation for generating a received signal stationary with respect to the ground. Are also described in detail and are discussed for OFDM demodulation. However, unlike Patent Document 1 having a transmission / reception configuration, it is discussed as a receiving device.
FIG. 24 is a block diagram illustrating a receiving device of Non-Patent Document 1, and FIG. 25 is a diagram illustrating the movement of the reception point x described above with respect to the interpolation processing of Non-Patent Document 1. In FIG. 25, GI281 represents a guard interval period, and DATA282 represents a valid symbol period.

In FIG. 24, similarly to Patent Document 1, signals received by the antennas 261 to 26K are interpolated by the interpolator unit 271 to compensate for fading fluctuations. Here, the Interpolator unit 271 corresponds to the interpolation calculation unit 208 of Patent Document 1.
The relative position unit 273 is a block that calculates the distance x necessary for performing the interpolation operation in the interpolator unit 271, and corresponds to the movement distance estimation unit 209 of Patent Document 1. Here, the reference time signal t is output together with the demodulated signal from the OFDM receiver unit 272, and the distance x is calculated using this time signal t. As shown in FIG. 25, the distance x is discontinuous for each symbol section. This is because the distance x is reduced to the start point for each OFDM symbol interval in order to prevent the distance x from increasing monotonously infinitely to be extrapolated. More specifically, the functions for calculating the distance x are expressed by Equations 2 and 3.

It differs from Patent Document 1 in that the distance x is periodically reduced to the start point based on the OFDM symbol interval information that is the reference time signal. Here, as described in the background art, the OFDM symbol period is composed of a guard interval period and an effective symbol period. Hereinafter, the guard interval length is denoted as Tg, the effective symbol period length as Tu, and the 1 symbol period length as Ts. From Equation 2 and FIG. 25, x is reduced to the start point every symbol period, and although it is discontinuous between symbols, there is no problem because it is within the guard interval.

  When the antenna input signal is expressed by Equation 4, the Interpolator unit 271 calculates the received signal r (t; x) at the reception point P by executing the weighting calculation of Equation 5. Here, the weighting is expressed by Equation 6 based on the distance x. P, which is a cross-correlation vector between the reception signals of the antennas 261 to 26K and the reception signal at the reception point P, is expressed by Equations 7 and 8, and R which is a covariance matrix of the reception signals of the antennas 261 to 26K is Equation 9, It is calculated by Equation 10. Note that T in Equation 4 represents transposition, and H in Equations 6 and 9 represents Hermitian transposition. J0 is a first-order zeroth-order Bessel function, and λ represents the wavelength of the carrier wave.

  The configuration of the interpolator 271 is shown in a block diagram as shown in FIG. The interpolator unit 271 includes a matrix R ^ -1 generation unit 291, a vector P generation unit 292, a vector W generation unit 293, and a virtual received signal main generation unit 294. Here, “R ^ −1” indicates an inverse matrix of the matrix R. The matrix R is uniquely obtained from Equation 9 and Equation 10 from the inter-antenna distance d and the wavelength of the carrier wave, and therefore the matrix R ^ -1 is also uniquely obtained. Thus, the matrix R ^ -1 generation unit 291 calculates the matrix R ^ -1, and the vector P generation unit 292 calculates the vector P using Equation 8. The vector W generation unit 293 calculates the weighting coefficient W by the calculation of Equation 6, and the virtual reception signal main generation unit 293 generates a reception signal at a virtual reception point stationary with respect to the ground from Equation 5.

As a result, a signal with constant fluctuation in fading can be created, and reception performance is improved in mobile reception.
JP 2002-152105 A (P3 to P6, FIGS. 1 to 3) Effect of improving high-speed mobile reception characteristics of digital terrestrial broadcasting due to time-varying propagation using an array antenna. 2, pp. 237-244 (2002)

  However, in the methods shown in Patent Document 1 and Non-Patent Document 1, all of the reception signals of the antennas 221 to 22K or the antennas 261 to 26K are used to generate a virtual reception signal that is stationary with respect to the ground. Therefore, the reception characteristics such as the voltage standing wave ratio (VSWR) and the radiation characteristics in the signal band must be uniform between the antennas. Therefore, if the reception characteristic of one antenna deteriorates, the average reception level at the antenna decreases compared to the other antennas, and as a result, the reception quality of the created virtual reception signal is greatly deteriorated. There was a problem.

More specifically, it is as follows.
The method of combining antenna reception signals by diversity reception suppresses the influence on the combined signal due to poor quality received signals by calculating weights according to the quality of the signal itself such as reception level and SN ratio. It is possible. On the other hand, the virtual received signal is calculated by taking the inner product of the weighting coefficient shown in Expression 5 and each received signal, and this weighting coefficient is calculated in the matrix R as calculated in Expression 4 to Expression 10. Is calculated with respect to the distance d between the antennas and the wavelength λ of the carrier wave, and the vector p is calculated by a function related to the distance d between the antennas, the wavelength λ of the carrier wave and the distance x of the virtual reception point P. In other words, the weighting coefficient is calculated regardless of the quality of the received signal of the antenna, and if the received signal of the antenna having a deteriorated reception characteristic is used, the quality of the calculated virtual received signal is deteriorated. It is. Since this weighting coefficient is determined by the mutual arrangement of the antennas as shown in Equations 6 to 10, in Equation 5, an element of the weighting vector W corresponding to an antenna that is not used or a received signal It cannot be solved simply by setting the element of the vector r to 0.

  The present invention solves the above-mentioned conventional problem, and even if the reception characteristics of a certain antenna among the plurality of reception antennas deteriorate, the deterioration of the quality of the received signal at the virtual reception point is minimized. The purpose is to enable stable reception in a mobile object.

  In order to solve the conventional problem, a receiving apparatus according to claim 1 of the present invention includes a receiving characteristic measuring unit that measures and evaluates receiving characteristics of a plurality of received signals, and a point relatively stationary with respect to the ground. A virtual reception signal creation unit that creates a virtual reception signal in the virtual reception signal creation unit, and the virtual reception signal creation unit uses only a signal determined by the reception characteristic measurement unit and whose reception characteristic satisfies a predetermined characteristic. The virtual reception signal is created.

This makes it possible to create a reception signal at a virtual reception point that is stationary with respect to the ground without adaptively using a reception signal with poor reception characteristics, and to improve the reception quality of the virtual reception signal. Degradation can be minimized.
According to a second aspect of the present invention, in the receiving device according to the first aspect, the reception characteristic measuring unit includes a received signal strength measuring unit that measures a signal level of each received signal, and the received signal strength measurement. A plurality of comparison / determination units for comparing the measurement results of the signal levels of the respective reception signals by the unit with a threshold, and the reception characteristics of the respective reception signals are determined by the predetermined comparison units by the determination by the plurality of comparison / determination units. It is configured to determine whether or not the characteristics are satisfied.

Thus, by measuring the signal level of each received signal, it is possible to accurately detect a received signal having reception characteristics worse than a certain reference.
According to a third aspect of the present invention, in the receiving device according to the first aspect, the reception characteristic measuring unit includes a received signal strength measuring unit that measures a signal level of each received signal, and the received signal strength measurement. An average calculator for calculating the average value of the signal level measurement results of each received signal by the unit, an adder for adding the calculated average value and a constant, and each reception by the received signal strength measuring unit A plurality of comparison / determination units that compare the signal level measurement result with the output of the adder, and the reception characteristics of each received signal are determined by the plurality of comparison / determination units according to the predetermined characteristic. It is set as the structure which determines whether it satisfy | fills.

As a result, each signal level is measured, and a reception signal having a relatively poor reception characteristic with respect to the average value of the signal level can be detected with high accuracy.
According to a fourth aspect of the present invention, in the receiving device according to the second or third aspect, in the received signal strength measuring unit, the signal level of each received signal is the power of a predetermined time length of each received signal. The measurement is based on the average value.

As a result, the signal level can be stably measured.
According to a fifth aspect of the present invention, in the receiving device according to the first aspect, the virtual received signal generation unit calculates a cross-correlation between the plurality of received signals and the virtual received signal. Using the calculation result of the P generation unit, the matrix R generation unit that calculates the covariance of the plurality of reception signals, and the calculation result of the vector P generation unit, the signal that satisfies the predetermined characteristic and the virtual reception A vector P correction unit that calculates a cross-correlation with a signal, a matrix R correction unit that calculates a covariance of a signal whose reception characteristics satisfy a predetermined characteristic, using the calculation result of the matrix R generation unit, and the matrix A matrix R ^ -1 generation unit that generates an inverse matrix of the matrix corrected by the R correction unit, and calculates a weighting coefficient from the output of the vector P correction unit and the output of the covariance correction unit A W generator, A serial vector W generator, said calculating a virtual reception signal using the plurality of received signals, and configured.
Further, the receiving apparatus according to claim 6 is the receiving apparatus according to claim 5, wherein the vector P correcting unit is configured to output the receiving characteristic measuring unit among the plurality of received signals at an output of the vector P generating unit. The cross-correlation value corresponding to a received signal other than the signal determined to satisfy the predetermined characteristic at 0 is set to 0, and the matrix R correcting unit includes, among the plurality of received signals, at the output of the matrix R generating unit, The covariance value corresponding to a received signal other than the signal determined to satisfy the predetermined characteristic by the reception characteristic measuring unit is set to 0 and 1.

This makes it possible to create a virtual reception signal using only a reception signal having excellent reception characteristics, regardless of the reception characteristics of any reception signal.
In addition, the receiving device according to claim 7 is the number of signals satisfying a predetermined characteristic having a reception characteristic determined by the reception characteristic measurement unit among the plurality of reception signals with respect to the reception apparatus according to claim 1. Is limited to an integer of 2 or more.

As a result, even if reception characteristics deteriorate, a virtual reception signal can be reliably generated using two or more reception signals.
Further, the receiving apparatus according to claim 8 is the number of signals satisfying a predetermined characteristic having a reception characteristic determined by the reception characteristic measuring unit among the plurality of reception signals, with respect to the receiving apparatus according to claim 1. Is set to 1, the creation of the virtual reception signal is stopped in the virtual reception signal creation unit.

As a result, when the number of reception signals having excellent reception characteristics becomes one, a virtual reception signal cannot be correctly created. Therefore, the reception characteristics of the reception signals can be reduced by demodulating the reception signals as they are. Deterioration can be suppressed.
Further, the receiving device according to claim 9 is different from the receiving device according to claim 1 in that
A reception device that receives a transmission signal in which data is transmitted for each symbol separated by a certain length, and in the virtual reception signal creation unit, selection of a reception signal used for creation of the virtual reception signal, It is configured to keep constant within the symbol.

This makes it possible to correctly create a virtual received signal without becoming discontinuous within the symbol period.
The receiving device according to claim 10 is different from the receiving device according to claim 1 in that, in the virtual reception signal generating unit, a point relatively stationary with respect to the ground is The moving body moves in the opposite direction to the moving direction at the same speed as the moving body, and returns to the starting point for the moving body at a predetermined periodic time interval. The starting point generates the virtual reception signal. The configuration is variable according to the combination of received signals used in the above.

As a result, the range of extrapolation processing can be minimized with respect to the arrangement of antennas to be used, and the accuracy of virtual received signals can be improved.
And the structure of the above Claims 1-11 enables the stable favorable reception in a high-speed moving body.

  According to the receiving apparatus of the present invention, it is possible to create a reception signal at a virtual reception point stationary with respect to the ground without adaptively using a reception signal having poor reception characteristics among a plurality of reception signals. Therefore, it is possible to minimize the degradation of the reception quality of the virtual reception signal. Also, depending on the arrangement of antennas with good reception characteristics, extrapolation processing may occur when creating virtual reception signals. However, interpolation processing should be performed by optimizing the position of virtual reception points. And a virtual received signal can be created with high accuracy. As a result, stable and good reception is possible in a high-speed moving body.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
Embodiment 1 of a receiving apparatus according to the present invention will be described with reference to FIGS.
1 is a diagram showing an antenna arrangement of a receiving apparatus according to Embodiment 1 of the present invention. The antenna arrangement in the receiving apparatus shown in FIG. 1 is similar to Patent Document 1, in which a plurality (K) of antennas are installed as the inter-antenna distance d in parallel with the traveling direction in which the moving body moves. Point P2 is an estimated virtual reception point, which will be described later. Here, the inter-antenna distance d and the number of antennas may be set in consideration of restrictions on the installation location, the wavelength of the carrier frequency of the received signal, cost, and the like.

  FIG. 2 is a block diagram showing a receiving apparatus according to Embodiment 1 of the present invention. The receiving apparatus includes antennas 101 to 10K and tuners 111 to 11K, a reception characteristic measurement unit 51, a virtual reception signal generation unit 5, a moving speed estimation unit 11, a demodulation unit 31 that performs demodulation processing, and an MPEG (Moving Picture Experts Group) -2. The decoding part 21 which decodes the signal compressed by etc., and the display part 22 which outputs video / audio are comprised.

  Based on the channel selection information signal, tuners 111 to 11K select reception signals of desired reception channels from the respective antennas 101 to 10K, perform level amplification (level adjustment), A / D conversion, and virtual reception The signal is passed to the signal generator 5 and the reception characteristic measuring unit 51. The virtual reception signal generation unit 5 includes a virtual reception signal calculation unit 13 and a movement distance estimation unit 12.

  In the moving distance estimation unit 12, the symbol position information signal that is the reference signal t (s) obtained from the demodulation unit 31 and the moving speed V (m / s) of the receiving device estimated by the moving speed estimation unit 11. Assuming a virtual reception point P2 that moves at a speed V (m / s) in the direction opposite to the moving direction, the distance x (m) from the antenna 101 of the reception point P2 at time t (s) is calculated. To the virtual received signal calculation unit 13. The distance x may be calculated using Equations 2 and 3 and moved as shown in FIG. 4, but is not limited to this. For example, instead of Equation 3, Equation 11 or Equation 12 may be used. Good.

Here, the moving speed estimator 11 may use a device that is a component outside the receiving device that measures the speed installed in the moving body as an estimation means, or estimates the Doppler shift from the received signal. By doing so, it may be configured to estimate the speed of the moving body, and any process may be used as long as the moving speed can be estimated.
The virtual reception signal calculation unit 13 estimates a reception signal (hereinafter referred to as a virtual reception signal a) at a virtual reception point P <b> 2 at a distance x and outputs the estimation signal to the demodulation unit 31. The virtual received signal calculation unit 13 will be described in detail later.

  FIG. 3 is a block diagram showing the configuration of the demodulator 31 in FIG. The demodulation unit 31 includes an orthogonal demodulation unit 41, an FFT unit 43, a symbol synchronization unit 44, a transmission path estimation unit 45, an equalization unit 46, and an error correction unit 47. The virtual received signal a is quadrature demodulated by the quadrature demodulation unit 41 and output to the FFT unit 43 and the symbol synchronization unit 44. The symbol synchronization unit 44 synchronizes the OFDM symbol section and outputs a symbol position information signal to the FFT unit 43 and the movement distance estimation unit 12. Based on the symbol position information signal, the FFT unit 43 performs a Fourier transform on the orthogonally demodulated signal to obtain a frequency domain signal. Thereafter, the transmission path estimation unit 45 performs transmission path estimation, and the equalization unit 46 equalizes the frequency domain signal based on the transmission path estimation. The equalized signal is input to the error correction unit 47 and error correction is performed.

The present embodiment is significantly different from the prior art in that a reception characteristic measurement unit 51 described below is newly provided and the virtual reception signal a is generated in the virtual reception signal calculation unit 13.
As shown in FIG. 5, the reception characteristic measurement unit 51 includes a reception signal strength measurement unit 52 and an effective reception characteristic determination unit 53. The received signal strength measuring unit 52 receives the received signals from the antennas 101 to 10K, measures the signal strength (signal level) of each received signal, and outputs the received signal level signal. The signal strength is calculated as an average value over the OFDM symbol length of the received signal. However, the average length of time is not limited to this. As shown in FIG. 6, the effective reception characteristic determination unit 53 includes an average value calculator 411, an adder 412, and comparison determination units 401 to 40 </ b> K. The average value calculator 411 calculates the average value of each received signal level. By calculating and comparing each received signal level signal obtained by adding a predetermined value to the average value by the comparison / determination units 401 to 40K, a signal having a relatively small level from the average value is determined as a signal having poor reception characteristics. Then, a reception characteristic information signal indicating whether reception characteristics of the reception signals of the antennas 101 to 10K are good or bad is output. Here, the average value of each received signal level is calculated. However, the median value of each received signal level may be calculated, and can be evaluated relatively to each received level. Anything can be used. Further, although the adder 412 adds a predetermined value to the average value, it may be multiplied by a predetermined value using a multiplier. Further, whether or not the predetermined characteristic is satisfied is evaluated using the signal level. However, the present invention is not limited to this, and the reception characteristic may be evaluated based on how the signal level varies.

  At this time, in order to perform the interpolation (or extrapolation) calculation in the virtual reception signal calculation unit 13, the reception signals of two or more antennas may be determined as signals having excellent reception characteristics. When it is determined that only one antenna is a good signal without adding such limitation, the generation of the virtual reception signal a is stopped and the reception signal of the one antenna is demodulated as it is. May be.

In addition, as shown in FIG. 7, the effective reception characteristic determination unit 53 includes a comparison determination unit 401 to 40 </ b> K as a reception characteristic determination method, and compares the reception signal level signal for each antenna with a predetermined value. If the received signal level signal is larger than the predetermined value, it may be determined that the reception characteristic is good, and if it is smaller than the predetermined value, it may be determined that the reception characteristic is bad.
The virtual reception signal calculation unit 13 uses the reception signal having the excellent reception characteristics determined by the reception characteristic measurement unit 51 among the reception signals of the antennas 101 to 10K, and calculates the virtual reception signal a at the virtual reception point P2. create.

As shown in FIG. 8, the virtual received signal calculation unit 13 includes a matrix R generation unit 64, a matrix R correction unit 65, a matrix R ^ (− 1) generation unit 61, a vector P generation unit 62, a vector P correction unit 66, A vector W generation unit 63 and a virtual reception signal main generation unit 67 are configured. Here, “R ^ (− 1)” indicates an inverse matrix of the matrix R.
As shown in Equations 6 to 10, the vector W is a vector P and a matrix R for all K existing antennas depending on the distance between the antennas and the distance from the virtual reception point P2 to each antenna. Are calculated by performing a matrix operation. Therefore, in order to create the virtual reception signal a without using the reception signal of the poor reception characteristic antenna, the vector element corresponding to the unused antenna in the vector W or the vector r in Equation 6 can be simply set to 0. It cannot be realized with simple processing. This is a significant difference from a method such as diversity combining in which the weighting coefficient and the element of the received signal vector r need only be zero.

  That is, as shown in FIG. 9A, for example, when the reception characteristics of the antenna 102 among the four antennas 101 to 104 are deteriorated and are not used for creating the virtual reception signal a, FIG. ), It is necessary to calculate the matrix R and the vector P using the mutual relationship of only the remaining three antennas 101, 103, and 104, and calculate the weighting vector W. This is realized by the virtual received signal calculation unit 13 of the present invention shown in FIG.

  In FIG. 8, a matrix R generation unit 64 that calculates the covariance of K antennas 101 to 10K generates a matrix R from Equation 10 based on the wavelength λ based on the channel selection information signal. Further, the vector P generation unit 62 that calculates the correlation between the K antennas 101 to 10K and the virtual reception signal a is based on the wavelength λ based on the music selection information signal and the distance x that is the output of the movement distance estimation unit 12. A vector P (a column vector of K rows) is generated using Equation 8. After that, in the matrix R correction unit 65 (corresponding to the covariance correction unit of claim 6), the reception characteristic information signal is input, and the new row and column of the matrix R corresponding to the reception signal with inferior reception characteristics are deleted. A simple matrix R is created. This concept will be described with reference to FIG. Here, as an example, consider a case where the reception characteristics of the received signal of the second antenna 102 from the front among the four antennas 101 to 104 as shown in FIG. Of the 4 × 4 matrix R (Equation 13) using Equations 9 and 10 generated by the matrix R generator 64, the reception characteristic of the reception signal of the second antenna 102 from the reception characteristic information signal is degraded. Is obtained, and a new matrix R (Expression 14) of 3 rows and 3 columns corresponding to the antenna 102 is generated by cutting the second row and the second column. As a result, a matrix R representing the covariance of only the antennas 101, 103, and 104 shown in FIG. 9B can be generated. Here, an example of the deterioration of one of the four signals is shown. However, when m of the K signals deteriorates, the matrix R correction unit 65 similarly uses the matrix R of K rows and K columns. To generate a matrix of (Km) rows (Km) columns.

Similarly, the vector P correcting unit 66 also removes elements corresponding to the received signal having inferior quality indicated by the reception characteristic information signal from the column vector P of K rows generated in Expressions 7 and 8 (K−m). ) Generate a vector of rows.
The matrix R ^ -1 generation unit 61 calculates an inverse matrix of the matrix R corrected by the matrix R correction unit 65 and performs an operation on the vector W with the vector P corrected by the vector P correction unit 66. As the calculation, Equation 6 is obtained. When m of the K signals deteriorate, the number of elements of W is (K−m). Then, the virtual reception signal main generation unit 67 performs calculation with the vector r of (K−m) rows from which elements corresponding to m reception signals with inferior reception characteristics indicated by the reception characteristic information signal are removed, A virtual reception signal a is generated. This makes it possible to generate the virtual reception point a with a simple configuration.

Here, when using the reception characteristic information signal, in order to avoid the virtual reception signal a being discontinuous in the symbol, the selection of which antenna from which the reception signal is used to create the virtual reception signal a is an OFDM symbol. However, the present invention is not limited to this, and the selection may be changed as needed.
FIG. 10 is a simulation result showing the effect of the first embodiment. Here, there are four antennas, the reception characteristics of one antenna are degraded, and the bit error rate in the demodulated signal before error correction is measured. The modulation parameters and the like are shown in FIG. In FIG. 10, the horizontal axis is C / N (Carrier / Noise), and the vertical axis is the bit error rate. As shown in FIG. 10, the present invention is applied and the configuration in which an antenna having poor reception characteristics is not used than in the case where the present invention is not applied and all four antennas are used. It can be seen that better reception than before is possible.

With the above configuration, even when reception characteristics of some antennas among a plurality of antennas 101 to 10K deteriorate, reception quality of the virtual reception signal a can be minimized. In a high-speed moving body, stable and good reception is possible.
Note that each component of the receiving apparatus according to Embodiment 1 may be realized by an integrated circuit. At this time, each component may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

Furthermore, a program that performs at least a part of the reception processing in the receiving apparatus according to the first embodiment may be used, and is realized by using a reception method that performs at least a part of the reception processing in the receiving apparatus according to the first embodiment. May be.
Further, Embodiment 1 may be realized by combining any receiving device, receiving method, receiving circuit, or program that performs a part of the receiving processing that realizes Embodiment 1.

(Embodiment 2)
A receiving apparatus according to a second embodiment of the present invention will be described with reference to FIG. 1, FIG. 12, and FIG. The same constituent elements as those in FIGS. 2 to 6 and FIG.
FIG. 12 shows a block diagram of the receiving apparatus according to the second embodiment of the present invention, and FIG. 13 shows a block diagram of the virtual received signal calculation unit 14. The arrangement of the antennas 101 to 10K is as shown in FIG.

Compared with Embodiment 1, the receiving apparatus according to Embodiment 2 of the present invention uses a matrix R using reception characteristic information signals in the matrix R correction unit 75 and the vector P correction unit 76 of the virtual received signal calculation unit 14. The method of correcting the vector P is different.
The matrix R correction unit 75 is a row of the matrix R corresponding to a reception signal having a poor reception characteristic, which is indicated by the reception characteristic information signal, out of the matrix R generated by the matrix R generation unit 64 using Equations 9 and 10. Among the elements in the column, a new matrix R is generated with the diagonal component set to 1 and the rest set to 0. This is specifically shown using FIG. Here, as an example, the reception characteristic of the reception signal of the second antenna 102 from the front among the three antennas 101 to 103 shown in FIG. 14A is deteriorated (FIG. 14B). think of. Information in which the reception characteristic of the reception signal of the second antenna 102 is deteriorated from the reception characteristic information signal in the matrix R (Formula 15) of 3 rows and 3 columns generated using Equation 10 by the matrix R generation unit 64 Then, a new matrix R (Equation 16) is generated with the diagonal component as 1 and the rest as 0 among the elements in the second row and the second column corresponding to the antenna 102.

  Thereafter, the matrix R ^ -1 generator 71 generates an inverse matrix of a new matrix R. At this time, similarly to the matrix R corrected by the matrix R correction unit 75, the calculated inverse matrix also has a diagonal component of 1 in the row and column elements corresponding to the received signal whose reception characteristics are degraded. Other than the corner component is 0. Further, the matrix from which the rows and columns are deleted is an inverse matrix of the matrix R from which the corresponding rows and columns are deleted.

  This is shown in Equations 20 to 31 in a 3 × 3 matrix. The matrix R ′ in Expression 20 is obtained by deleting the second row and the second column of the matrix R. Equations 21 to 30 are obtained by calculating a determinant of the matrix R and cofactor expansion in order to obtain an inverse matrix of the matrix R, and using these, the inverse matrix of the matrix R is calculated by Equation 31. As described above, among the elements in the second row and the second column, the diagonal component is 1 and the other components are 0. Further, it can be easily understood that the matrix obtained by deleting the second row and the second column of the matrix 31 is an inverse matrix of the matrix R ′.

The same applies to the 1st row, the 1st column, and the 3rd row, the 3rd column regarding the 3 × 3 matrix, and the same can be said for the N × N matrix.
On the other hand, the vector P correction unit 76 generates a new vector P in which the row element corresponding to a received signal with poor reception characteristics is set to zero. From these, when the vector W generation unit uses the inverse matrix of the matrix R and the vector P, a vector W in which the row element corresponding to the received signal with inferior reception characteristics is 0 is generated. A virtual received signal a is generated using the vector W and the vector r. Here, the vector W ′ (column vector of (K−m)) in which the row elements of 0 corresponding to the received signal with poor quality of W (K row vector) are deleted is the embodiment. It can be easily confirmed that this is nothing but the vector W shown by 1. That is, the virtual reception signal a finally obtained is the same signal as that in the first embodiment.

Thus, unlike the first embodiment, the matrix R of K rows and K columns and the vectors P and W of K rows, which are a fixed number of rows and columns, are used regardless of the number of reception signals having inferior reception characteristics. Since each can be used for computation, there is an effect that the configuration becomes very easy.
With the above configuration, even if the quality of reception signals of some of the plurality of antennas 101 to 10K deteriorates, the reception characteristics of the virtual reception signal a are minimized. Therefore, stable and good reception is possible in a high-speed moving body.

Note that the effective reception characteristic determination unit 53 of the reception characteristic measurement unit 51 in FIG. 12 may use the effective reception characteristic determination unit 54 shown in FIG.
In addition, each component of the receiving apparatus according to the second embodiment may be realized by an integrated circuit. At this time, each component may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

Furthermore, a program that performs at least a part of the reception processing in the receiving apparatus according to the second embodiment may be used, and may be realized by using a reception method that performs at least a part of the reception processing in the receiving apparatus according to the second embodiment. May be.
Further, the second embodiment may be realized by combining any receiving device, receiving method, receiving circuit, or program that performs a part of the receiving process for realizing the second embodiment.

(Embodiment 3)
Embodiment 3 of the receiving apparatus according to the present invention will be described with reference to FIGS. 1 and 15 to 19. The same constituent elements as those in FIGS. 2 to 6 and FIG.
FIG. 15 is a block diagram showing a receiving apparatus according to the third embodiment of the present invention. The arrangement of the antennas 101 to 10K is as shown in FIG.

The receiving apparatus according to the third embodiment of the present invention is different from the first embodiment in the method of calculating the distance x from the antenna 101 at the virtual reception point P2 in the moving distance estimation unit 16.
The movement distance estimation unit 16 receives the reception characteristic information signal, and among the antennas having excellent reception characteristics, the distances (Ant_l and Ant_r) from the antenna 101 of the frontmost antenna and the rearmost antenna, respectively. And). Then, the distance x from the antenna 101 of the virtual reception point P2 is calculated using Equation 18 instead of Equation 3.

ここで、図１６で示すように、４本アンテナ１０１〜１０４において、仮想受信信号を作成することを考える。距離ｘの算出に数３を用いた場合の、仮想的な受信点Ｐ２の動く範囲を太い矢印で示している。

Here, as shown in FIG. 16, it is considered that a virtual reception signal is created in the four antennas 101 to 104. The range in which the virtual reception point P2 moves when Equation 3 is used to calculate the distance x is indicated by a thick arrow.

  As shown in FIG. 17, when the reception characteristics of the received signal of the antenna 101 deteriorate, assuming that the distance x is calculated by the conventional equation 3, the virtual received signal a using the remaining three antennas 102 to 104 An operation may be an extrapolation process. As shown in FIG. 18, this is extrapolated by using Equation 18 and adaptively controlling the starting position of the distance x according to the arrangement of the antennas having excellent reception characteristics used to create the virtual reception signal a. The range can be minimized.

  FIG. 19 is a simulation result showing the effect of the fourth embodiment. Here, the number of antennas is four, the reception characteristics of one antenna are deteriorated, and the bit error rate in the demodulated signal before error correction is measured. Equation 18 is used as an equation for calculating the virtual reception point P2. The modulation parameters and the like are shown in FIG. In FIG. 19, the horizontal axis is C / N (Carrier / Noise), and the vertical axis is the bit error rate. As shown in FIG. 19, the fourth embodiment of the present invention in which the adaptive control of the virtual reception point P2 is performed is used rather than the first embodiment of the present invention in which the adaptive control of the virtual reception point P2 is not performed. It can be seen that the above-described configuration can further reduce the error rate and can perform better reception than before.

  With the above configuration, even when reception characteristics of some antennas among the plurality of antennas 101 to 10K deteriorate, reception characteristics of the virtual reception signal a are minimized. be able to. Further, adaptive control of the moving position of the virtual reception point P2 with respect to the antenna arrangement used can prevent the interpolation system from deteriorating. These enable stable and good reception in a high-speed moving body.

  Note that the calculation of the distance x is not limited to Equation 18, and may be, for example, Equation 17 or Equation 19. Furthermore, the effective reception characteristic determination unit 53 of the reception characteristic measurement unit 51 may be the effective reception characteristic determination unit 54 shown in FIG. 7, and the virtual reception signal calculation unit 13 calculates the virtual reception signal calculation shown in FIG. It is good also as part 14.

なお、実施の形態３の受信装置の各構成要素は、集積回路で実現してもよい。このとき、各構成要素は、個別に1チップ化されてもよいし、一部もしくは全てを含むように１チップ化されてもよい。

Note that each component of the receiving apparatus according to Embodiment 3 may be realized by an integrated circuit. At this time, each component may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

Furthermore, a program that performs at least a part of the reception processing in the receiving apparatus according to the third embodiment may be used, and is realized by using a reception method that performs at least a part of the reception processing in the receiving apparatus according to the third embodiment. May be.
Further, Embodiment 3 may be realized by combining any receiving device, receiving method, receiving circuit, or program that performs a part of the receiving processing that realizes Embodiment 3.

  In the first to third embodiments, the guard interval period has been described on the assumption that part of the signal of the effective symbol period is copied to the guard period. It is not a thing. Moreover, although Embodiment 1-3 demonstrated as an OFDM signal, not only this but single carrier transmission may be sufficient, and in order to return distance x to a starting point, a preamble signal etc. It is only necessary to include a signal corresponding to the guard interval period.

  The receiving apparatus according to the present invention has a function of reducing inter-carrier interference caused by frequency fluctuations caused by Doppler shift, wireless communication including wireless LAN, wireless PAN, wireless WAN, and wireless MAN, and ground / satellite This is useful in relay devices and receivers in digital broadcasting, and in receivers in a wide range of fields such as measurement.

The figure which shows arrangement | positioning of the antenna of the receiver in Embodiment 1 of this invention Block diagram of receiving apparatus in embodiment 1 of the present invention Block diagram of demodulator 31 in Embodiment 1 of the present invention The figure showing the relationship between the distance x of the movement distance estimation part 12 in FIG. 2, and time. Block diagram of reception characteristic measurement unit 51 in Embodiment 1 of the present invention Block diagram of quality degradation signal determination unit 53 in Embodiment 1 of the present invention The block diagram of the quality degradation signal determination part 54 different from FIG. 6 in Embodiment 1 of this invention. The block diagram of the virtual received signal calculating part 13 in Embodiment 1 of this invention. Conceptual diagram of corresponding antenna arrangement when using only high-quality signals The graph which shows the effect of Embodiment 1 of the present invention The figure which shows the conditions of the simulation of Embodiment 1 of this invention Block diagram of receiving apparatus according to Embodiment 3 of the present invention The block diagram of the virtual received signal calculating part 14 of Embodiment 3 of this invention. Conceptual diagram of corresponding antenna arrangement when using only high-quality signals Block diagram of receiving apparatus according to embodiment 4 of the present invention Conceptual diagram showing the arrangement of four antennas and the range of movement of the virtual reception point P according to Equation 3 Conceptual diagram showing the corresponding antenna arrangement when only a good quality signal is used and the range of movement of the virtual receiving point P according to Equation 3 Conceptual diagram showing the corresponding antenna arrangement when only a good quality signal is used and the range of movement of the virtual receiving point P according to Equation 16. The graph which shows the effect of Embodiment 4 of this invention The block diagram which shows antenna arrangement | positioning in the conventional transmission / reception apparatus (patent document 1) Block diagram showing a conventional transmission / reception apparatus (Patent Document 1) The block diagram which shows the structure of the conventional (patent document 1) base station The figure showing the relative position with respect to the ground of the transmission / reception timing of Patent Document 1 and the antennas 221 and 22K Block diagram showing a conventional (non-patent document 1) receiving device The figure showing the periodicity of the distance x in the relative position part 271 of the past (nonpatent literature 1). A block showing a conventional (Non-Patent Document 1) Interpolator 271

Explanation of symbols

1 Mobile 2 Virtual reception point P
DESCRIPTION OF SYMBOLS 5 Virtual received signal production part 6 Virtual received signal production part 7 Virtual received signal production part 11 Movement speed estimation part 12 Movement distance estimation part 13 Virtual reception signal calculation part 14 Virtual reception signal calculation part 16 Movement distance estimation part 21 Decoding part 22 Display Unit 31 demodulator 41 orthogonal demodulator 43 FFT unit 44 symbol synchronization unit 45 transmission path estimation unit 46 equalization unit 47 error correction unit 51 reception characteristic measurement unit 52 received signal strength measurement unit 53 effective reception characteristic determination unit 54 effective reception characteristic determination 54 Unit 61 Matrix R ^ -1 generator 62 Vector P generator 63 Vector W generator 64 Matrix R generator 65 Matrix R corrector 66 Vector P corrector 67 Virtual received signal main generator 71 Matrix R ^ -1 generator 73 Vector W generation unit 75 Matrix R correction unit 76 Vector P correction unit 77 Virtual received signal main generation unit 101 to 10K An Tena 111-11K tuner 201 Modulation unit 202 Modulation parameter control unit 203 Instantaneous fading estimation unit 204 Demodulation unit 205-207 Switching unit 208 Interpolation calculation unit 209 Moving distance estimation unit 210 Received signal estimation unit 221-22K Antenna 230 Mobile unit 241 Modulation Parameter estimation unit 242 Demodulation unit 243 Instantaneous fading estimation unit 244 Modulation parameter control unit 245 Modulation unit 246 Switching unit 261 to 26K Antenna 271 Interpolator unit 272 OFDM Receiver unit 273 Relative Position unit 281 Guard interval section 282 Data section (effective symbol section)
291 Matrix R ^ -1 generation unit 292 Vector P generation unit 293 Vector W generation unit 294 Virtual reception signal generation unit 401 to 40K Comparison determination unit 411 Average value calculation unit 412 Adder

Claims (14)

A receiving device for performing digital communication,
A reception characteristic measurement unit that measures and evaluates reception characteristics of a plurality of reception signals;
A virtual reception signal creation unit that creates a virtual reception signal at a point relatively stationary with respect to the ground,
The virtual reception signal creation unit creates the virtual reception signal using only a signal determined by the reception characteristic measurement unit and having a reception characteristic satisfying a predetermined characteristic. The reception characteristic measurement unit includes a reception signal strength measurement unit that measures a signal level of each reception signal, and
A plurality of comparison / determination units for comparing the measurement result of the signal level of each received signal by the received signal strength measuring unit with a threshold;
The receiving apparatus according to claim 1, wherein, by the determination by the plurality of comparison / determination units, it is determined whether or not a reception characteristic of each received signal satisfies the predetermined characteristic. The reception characteristic measurement unit includes a reception signal strength measurement unit that measures a signal level of each reception signal, and
An average calculator that calculates an average value of the measurement results of the signal level of each received signal by the received signal strength measuring unit;
Furthermore, an adder that adds the calculated average value and a certain constant;
A plurality of comparison / determination units for comparing the measurement result of the signal level of each reception signal by the reception signal strength measurement unit with the output of the adder;
The receiving apparatus according to claim 1, wherein, by the determination by the plurality of comparison / determination units, it is determined whether or not a reception characteristic of each received signal satisfies the predetermined characteristic. In the received signal strength measuring unit, the signal level of each received signal is:
The receiving apparatus according to claim 2, wherein the receiving apparatus measures the average value of power in a predetermined time length of each received signal. The virtual received signal generator is
A vector P generator for calculating a cross-correlation between the plurality of received signals and the virtual received signal;
A matrix R generator for calculating a covariance of the plurality of received signals;
Using the calculation result of the vector P generation unit, a vector P correction unit that calculates a cross-correlation between a signal whose reception characteristic satisfies a predetermined characteristic and the virtual reception signal;
A matrix R correction unit that calculates covariance of a signal whose reception characteristic satisfies a predetermined characteristic, using a calculation result of the matrix R generation unit;
A matrix R ^ -1 generation unit that generates an inverse matrix of the matrix modified by the matrix R modification unit, and
A vector W generation unit for calculating a weighting coefficient from the output of the vector P correction unit and the output of the covariance correction unit,
The receiving device according to claim 1, wherein the virtual received signal is calculated using the vector W generation unit and the plurality of received signals. The vector P correction unit, at the output of the vector P generation unit,
Among the plurality of received signals, the cross-correlation value corresponding to a received signal other than the signal determined to satisfy the predetermined characteristic by the reception characteristic measuring unit is set to 0,
The matrix R correction unit is configured to output an output from the matrix R generation unit.
6. The receiving apparatus according to claim 5, wherein among the plurality of received signals, covariance values corresponding to received signals other than the signal determined to satisfy the predetermined characteristic by the reception characteristic measuring unit are set to 0 and 1. . Among the plurality of received signals,
The receiving apparatus according to claim 1, wherein the number of signals satisfying a predetermined characteristic having a reception characteristic determined by the reception characteristic measurement unit is limited to an integer of 2 or more. Among the plurality of received signals,
When the number of signals satisfying a predetermined characteristic with a reception characteristic determined by the reception characteristic measurement unit is 1,
The receiving device according to claim 1, wherein the virtual reception signal creation unit stops creating the virtual reception signal. A receiving device that receives a transmission signal in which data is transmitted for each symbol separated by a certain length,
The receiving apparatus according to claim 1, wherein the virtual reception signal creation unit keeps selection of a reception signal used to create the virtual reception signal constant within the symbol. In the virtual reception signal creation unit, the point stationary relative to the ground moves in the direction opposite to the moving direction of the moving body at the same speed as the moving body,
Return to the starting point for the moving body at a certain periodic time interval,
The receiving apparatus according to claim 1, wherein the start point varies according to a combination of received signals used for creating the virtual received signal. A receiving device for performing digital communication,
A plurality of tuners for selecting signals in a desired frequency band from reception signals received via a plurality of antennas;
A reception characteristic measurement unit that measures and evaluates reception characteristics of reception signals selected by the plurality of tuners;
A virtual reception signal creation unit that creates a virtual reception signal at a point relatively stationary with respect to the ground;
A demodulator that demodulates the virtual received signal;
A decoding unit that decodes the demodulated signal demodulated by the previous demodulation unit;
A display unit for outputting audio or video of the signal decoded by the decoding unit,
The virtual reception signal creation unit creates the virtual reception signal using only a signal determined by the reception characteristic measurement unit and having a reception characteristic satisfying a predetermined characteristic. A receiving method for performing digital communication,
A reception characteristic measurement step for measuring and evaluating reception characteristics of a plurality of reception signals;
A virtual reception signal creation step for creating a virtual reception signal at a point relatively stationary with respect to the ground, and
The reception method in which the virtual reception signal creation step creates the virtual reception signal using only a signal having a reception characteristic that satisfies a predetermined characteristic, which is determined in the reception characteristic measurement step. A receiving circuit for performing digital communication,
A reception characteristic measurement circuit that measures and evaluates reception characteristics of a plurality of reception signals; and
A virtual reception signal generation circuit for generating a virtual reception signal at a point relatively stationary with respect to the ground,
The virtual reception signal creation circuit creates the virtual reception signal using only a signal determined by the reception characteristic measurement circuit and having a reception characteristic satisfying a predetermined characteristic. A program for receiving processing in digital communication,
A reception characteristic measurement step for measuring reception characteristics of a plurality of reception signals;
A virtual reception signal creation step for creating a virtual reception signal at a point relatively stationary with respect to the ground, and
The virtual reception signal creation step creates the virtual reception signal using only the signal having the reception characteristic that satisfies the predetermined characteristic, which is determined in the reception characteristic measurement step.

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