JP2014183532A - Radio communication system, radio communication device and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device using optimized signal constellation for a multipolarized spatial multiplex transmission system.SOLUTION: A transmitter 1000 performs transmission using a multipolarized wave spatial multiplex transmission system, in which a signal point is allocated onto a vertical polarization wave, a horizontal polarization wave, and a space consisting of the vertical polarized wave and the horizontal polarized wave. An I/Q mapping data storage part 106 stores signal constellation, calculated so as to minimize the maximum value of Hamming distance ratio to an Euclidean distance in a set of transmission symbols. A V/H mapping processing part 104 allocates output of an error correction coding processing part onto plane of in-phase component and quadrature-phase component, within the vertical polarization wave and the horizontal polarization wave on the basis of the stored signal constellation in the multipolarized wave spatial multiplex transmission system.

Description

  The present invention relates to a wireless communication apparatus, a wireless communication system, and a wireless communication method that communicate with signals of a plurality of polarizations.

  For modulation schemes for digital transmission, phase modulation (PSK modulation) in which information is transmitted by changing the phase of the carrier wave, quadrature amplitude modulation (QAM) in which the transmission speed (frequency utilization efficiency) is increased by changing the amplitude and phase are often used. Used.

  In these modulation schemes, the transmission rate can be increased by increasing the number of bits per symbol, but the linear distance between symbols (Euclidean distance) is reduced, so that the same bit error rate (BER) is achieved. This requires high signal power. Under the condition of constant transmission power, it is important to increase the minimum inter-symbol distance (minimum Euclidean distance) to improve the bit error rate. Arrangement) is known (see, for example, Non-Patent Document 1).

  In addition, in an additive white Gaussian noise (AWGN) environment, symbol errors occur between adjacent symbols on the phase plane, so that graying is performed so that the adjacent symbols have a 1-bit difference (Hamming distance is 1). It is known that the bit error rate of each modulation method can be minimized by using the signal point arrangement. Furthermore, a trellis coded modulation method (TCM) is known as a coded modulation method that increases an Euclidean distance equivalently by combining an error correction code and digital modulation (for example, see Non-Patent Document 2).

  On the other hand, in recent years, with the widespread use of wireless communication systems, a shortage of frequency resources has become apparent, especially in the microwave band, and transmission techniques for achieving high frequency utilization efficiency are required. The orthogonal polarization multiplexing technique pays attention to the wavefront direction of a radio wave radiated from an antenna, and transmits independent signals having wavefronts orthogonal to each other at the same frequency.

  When this orthogonal multiplexing polarization technology is applied, in the case of linear polarization used in fixed wireless communication or the like, V and H polarization multiplexing using vertical (V) polarization and horizontal (H) polarization can be realized. In this case, the frequency utilization efficiency is doubled compared to the case where the orthogonal polarization multiplexing technique is not applied (see, for example, Patent Document 1). The V and H polarization multiplexed signals can be transmitted and received by, for example, arranging two linear radiating elements orthogonally in a cross shape.

  Furthermore, in satellite communication, a polarization multiplexing scheme is known in which signals are multiplexed on three or more polarizations that are not necessarily orthogonal to improve frequency utilization efficiency (see, for example, Non-Patent Document 3). In this method, a bit is assigned to each polarization, and the signal point is obtained by multiplexing (synthesizing) the values obtained by mapping each polarization component before synthesis onto the horizontal (H) / vertical (V) polarization IQ plane. Form. At this time, the signal point arrangement is optimized so that the minimum Euclidean distance between symbols on each polarization of H / V is maximized.

JP 2007-189306 A

Gerard J. Foschini, Richard D. Gitlin, Stephen B. Weinstein, “Optimization of Two-Dimensional Signal Constellation in the Presence of Gaussian Noise”, IEEE Trans. Commun., Vol. COM-22, No. 1, pp. 28 -38, Jan. 1974. G. Ungerboeck “Trellis-coded modulation with redundant signal sets part 1 and part 2”, IEEE Comm. Mag., Vol. 25, No. 2, pp. 5-21, 1987. Yafune, Webber, Yano, Ban, Kobayashi, "Proposal of Multi-Polarization Spatial Multiplexing Technology for Satellite Communications", IEICE Technical Report, Vol. 112, No. 191, pp.1-5, Aug. 2012.

  However, when error correction coding is performed, error tolerance for each bit of each symbol is different, and therefore it is not necessarily obvious whether the signal point arrangement with the maximum minimum Euclidean distance is optimal as error tolerance. In addition, it is not realistic to verify all the signal point arrangements that can be generated one by one, and it is not easy to optimize the coding / modulation scheme according to the error correction decoding scheme as described above in TCM, At present, there is no method for easily and directly deriving the optimal signal point arrangement.

The present invention has been made to solve the above problems, and its purpose is as follows.
To provide a wireless communication system, a wireless communication apparatus, and a wireless communication method using a signal point arrangement optimized for a multi-polarization spatial multiplexing transmission system.

  According to one aspect of the present invention, wireless communication performs transmission / reception using a multi-polarization spatial multiplexing transmission system in which signal points are assigned to vertical polarization, horizontal polarization, and a space constituted by vertical and horizontal polarization. A system comprising a transmitter and a receiver, the transmitter including a transmission antenna, an error correction coding processing unit for performing error correction coding processing on a transmission symbol, and a first storage unit The first storage unit is a function of the Euclidean distance and the Hamming distance, and is a predetermined set of transmission symbols of a function that monotonously increases as the Euclidean distance decreases and increases monotonously as the Hamming distance increases. The signal point constellation calculated so as to minimize the maximum value is stored, and based on the information stored in the first storage unit, the output of the error correction coding processing unit in the multi-polarization spatial multiplexing transmission system Based on the processing result of the mapping processing unit and the mapping processing unit assigned in the in-phase component and the orthogonal phase component plane in the vertical polarization and the horizontal polarization, and executing the quadrature modulation for the vertical polarization and the horizontal polarization, A receiver that transmits from the transmission antenna, the receiver includes a reception antenna, a reception unit that performs quadrature detection on the vertically polarized wave and the horizontally polarized wave, respectively, for the signal received by the receive antenna; A second storage unit that stores information corresponding to the signal point arrangement stored in the storage unit, and a vertical polarization and a horizontal polarization in the multi-polarization spatial multiplexing transmission system based on the information stored in the second storage unit. For polarization, a maximum likelihood determination processing unit for executing maximum likelihood determination and an error correction decoding processing unit for executing error correction decoding processing based on the determination result of the maximum likelihood determination processing unit are included. .

  Preferably, the function is a ratio of the Hamming distance to the Euclidean distance in a predetermined set of transmission symbols.

  Preferably, the multi-polarization spatial multiplexing transmission system is a non-orthogonal polarization multiplexing system.

  Preferably, the multi-polarization spatial multiplexing transmission system is a multi-polarization spatial modulation system.

  According to another aspect of the present invention, wireless communication that performs transmission using a multi-polarization spatial multiplexing transmission system that assigns signal points to vertical polarization, horizontal polarization, and a space composed of vertical and horizontal polarization An apparatus comprising: a transmission antenna; an error correction encoding processing unit for executing error correction encoding processing on a transmission symbol; and a storage unit, wherein the storage unit is a function of Euclidean distance and Hamming distance. Storing the signal point arrangement calculated so as to minimize the maximum value in a predetermined set of transmission symbols of a function that increases monotonously with decreasing Euclidean distance and monotonically increases with increasing Hamming distance. Based on the information stored in the storage unit, in the multi-polarization spatial multiplexing transmission system, the output of the error correction coding processing unit is converted to the in-phase and quadrature component planes in the vertical polarization and the horizontal polarization. Based on the assigned mapping processor, mapping processing unit processing result, by executing the orthogonal modulation for the vertically polarized waves and horizontally polarized waves, further comprising a transmitting unit for transmitting from the transmitting antenna.

  According to still another aspect of the present invention, wireless reception is performed using a multi-polarization spatial multiplexing transmission system in which signal points are assigned to vertical polarization, horizontal polarization, and a space constituted by vertical and horizontal polarization. A communication device, comprising: a reception antenna; a reception unit that performs quadrature detection for vertical polarization and horizontal polarization for a signal received by the reception antenna; and a storage unit, wherein the storage unit includes a Euclidean distance and A function of the Hamming distance, which increases monotonically with decreasing Euclidean distance, and that increases monotonically with increasing Hamming distance, and is calculated to minimize the maximum value in a given set of transmitted symbols. The signal point arrangement is stored, and the maximum likelihood determination is executed for the vertical polarization and the horizontal polarization in the multi-polarization spatial multiplexing transmission system based on the information stored in the storage unit. Further comprising a maximum likelihood determination processing of the eye, based on the determination result of the maximum likelihood determination processing unit, an error correction decoding unit for performing error correction decoding.

  Preferably, the function is a ratio of the Hamming distance to the Euclidean distance in a predetermined set of transmission symbols.

  Preferably, the multi-polarization spatial multiplexing transmission system is a non-orthogonal polarization multiplexing system.

  Preferably, the multi-polarization spatial multiplexing transmission system is a multi-polarization spatial modulation system.

  According to still another aspect of the present invention, wireless transmission / reception is performed in a multi-polarization spatial multiplexing transmission system in which signal points are assigned to vertical polarization, horizontal polarization, and a space constituted by vertical polarization and horizontal polarization. A communication method, wherein the transmitter performs error correction coding processing on the transmission symbol; and the transmitter is a function of the Euclidean distance and the Hamming distance, and monotonously increases as the Euclidean distance decreases, In addition, in a multi-polarization spatial multiplexing transmission system, an error correction code based on a signal point arrangement calculated to minimize the maximum value in a predetermined set of transmission symbols of a function that increases monotonically as the Hamming distance increases A mapping process for assigning the result of the conversion process to the in-phase and quadrature component planes in the vertical polarization and horizontal polarization, and the transmitter performs mapping Based on the results of the processing, orthogonal modulation is performed on the vertical polarization and horizontal polarization, and the signal is transmitted from the transmitting antenna, and the receiver performs quadrature detection on the vertical polarization and horizontal polarization of the received signal, respectively. A step in which the receiver performs a maximum likelihood determination for vertical polarization and horizontal polarization in a multi-polarization spatial multiplexing transmission system based on the signal point arrangement in the transmitter, and the receiver And executing an error correction decoding process based on the determination result of the maximum likelihood determination.

  According to the present invention, in a multi-polarization spatial multiplexing transmission system, transmission or reception can be performed with a signal point arrangement optimized so as to minimize bit errors.

It is a functional block diagram for demonstrating the structure of the transmitter 1000 of this Embodiment. It is a functional block diagram for demonstrating the structure of the receiver 2000 of this Embodiment. It is a conceptual diagram which shows the outline | summary of a non-orthogonal polarization multiplexing system. It is a conceptual diagram which shows the outline | summary of a multi-polarization spatial modulation system. It is a figure which shows the result of having performed optimization of the signal point arrangement | positioning of this Embodiment. This is the signal point arrangement shown as arrangement A in FIG. 5 is a signal point arrangement shown as arrangement B in FIG. 6 is a flowchart for explaining processing in a transmitter 1000 and a receiver 2000. It is a figure which shows the result of having confirmed the bit error rate in each signal point arrangement | positioning by computer simulation.

  Hereinafter, a radio communication system according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, components and processing steps given the same reference numerals are the same or equivalent, and the description thereof will not be repeated unless necessary.

  As will be described below, the wireless communication system of the present embodiment employs a polarization multiplexing communication system.

  Preferably, in the present embodiment, a communication device in a system that transmits information using two polarized waves is more suitable for use in a system system that does not stand out between transmission and reception, such as satellite communication. is there. Note that a communication device having only the transmission function can be configured to include only the transmission function of the present embodiment, and a communication device having only the reception function can be configured to include only the reception function of the present embodiment. The transceiver can also be configured to have a transmission / reception function.

  In addition, the wireless communication system of the present embodiment is a wireless communication device that simultaneously uses two orthogonal polarizations (which are orthogonal at a realistic level and the cross polarization component need not be 0) for information transmission. It is a target. However, in the transmitter, receiver, and transmitter / receiver of this embodiment, it is possible to temporarily stop the polarization multiplexing communication function as described below and switch to communication using the conventional communication method. It is also possible to configure the system.

(Configuration of transmitter and receiver)
FIG. 1 is a functional block diagram for explaining the configuration of transmitter 1000 according to the present embodiment.

  Referring to FIG. 1, transmitter 1000 receives an error correction coding processing unit 100 that receives a digital data signal (information bit) to be transmitted, performs error correction coding processing on the information bit, and converts the information bit into a transmission symbol. Is provided. In addition to the error correction coding process, an “interleave process” or the like may be executed.

  Transmitter 1000 further includes an S / P converter 102 for serial / parallel conversion (S / P conversion) of symbols to be transmitted, and a transmission symbol converted to a parallel signal in I / Q mapping data storage unit 106. V / H mapping processing for mapping each polarization component of horizontal polarization (H polarization) and vertical polarization (V polarization) to signal points in a signal space diagram (constellation) based on the retained information Unit 104.

  Here, the I component means an in-phase component in quadrature modulation, the Q component means a quadrature phase component in quadrature modulation, and I / Q mapping means I component and Q component. This means that signal points are arranged on a plane stretched by.

  The transmitter 1000 further includes a quadrature modulation unit 108a that quadrature modulates the I / Q component for V polarization from the V / H mapping processing unit 104 with a corresponding modulation scheme (for example, QPSK modulation scheme), and V / H A quadrature modulation unit 108b that quadrature modulates the I / Q component for H polarization from the H mapping processing unit 104 with a corresponding modulation scheme (for example, QPSK modulation scheme), and a digital-analog conversion of the output of the quadrature modulation unit 108a A D / A conversion unit 110a for converting the output of the quadrature modulation unit 108b and a D / A conversion unit 110b for digital / analog conversion of the output of the orthogonal modulation unit 108b.

  The output of the D / A conversion unit 110a is amplified by a power amplifier (not shown), subjected to filter processing for suppressing unnecessary frequency components by the transmission filter processing unit 112a, and then transmitted from the vertically polarized antenna 114a. The output of the D / A conversion unit 110b is amplified by a power amplifier (not shown), filtered by the transmission filter processing unit 112b, and then transmitted from the horizontal polarization antenna 114b.

  FIG. 2 is a functional block diagram for explaining the configuration of the receiver 2000 of the present embodiment.

  Referring to FIG. 2, receiver 2000 performs a reception filter for filtering a signal amplified by a low-noise amplifier (not shown) of a reception signal from vertical polarization antenna 200a, horizontal polarization antenna 200b, and vertical polarization antenna 200a. A processing unit 202a, a reception filter processing unit 202b for filtering a signal amplified by a low noise amplifier (not shown) from a reception signal from the horizontally polarized antenna 200b, and an analog-to-digital conversion for a signal from the reception filter processing unit 202a An analog-digital conversion unit (A / D conversion unit) 204a and an A / D conversion unit 204b for analog-digital conversion of a signal from the reception filter processing unit 202b are provided.

  Receiver 2000 further includes quadrature detection units 206a and 206 that receive signals from A / D conversion units 204a and 204b, respectively, and separate I / Q components on the constellation.

  Based on the mapping information from the I / Q mapping data storage unit 210, the maximum likelihood determination processing unit 208 calculates the likelihood for a predetermined signal point on the signal space diagram for the signals from the quadrature detection units 206a and 206b. The maximum likelihood decoding is performed by the MLD (Maximum Likelihood Detection) method. In the MLD method, a metric is calculated using all combinations of transmission signals that can be transmitted from a transmission antenna with respect to a reception signal. Then, a combination of transmission signals that gives the minimum distance is selected.

  The “signal point” refers to a reference position defined on the constellation by the modulation method, and the “symbol” is a unit of information that is modulated on the transmission side and transmitted by the reference clock. Means “sign”.

  The bit information of the transmission signal calculated by the maximum likelihood determination processing unit 208 is subjected to error correction by the error correction decoding processing unit 214 via the P / S conversion unit 212 that performs parallel / serial conversion (P / S conversion). Are output as received symbols.

Note that convolutional decoding and deinterleaving processing may be performed in the error correction decoding processing unit 214 according to the configuration on the transmitter side.
(Signal system for improving frequency utilization efficiency in orthogonal polarization multiplexing)
As described in Non-Patent Document 3 described above, in the orthogonal polarization multiplexing method, “non-orthogonal polarization multiplexing method” and “multi-polarization spatial modulation method” are used as methods for improving the frequency utilization efficiency. Has been proposed.

  The following is a summary of the contents.

(Non-orthogonal polarization multiplexing)
FIG. 3 is a conceptual diagram showing an outline of the non-orthogonal polarization multiplexing system.

  Referring to FIG. 3 (a), in this non-orthogonal polarization multiplexing system, a non-orthogonal polarization (represented as S in FIG. 3 (a)) is additionally combined with the orthogonal H / V polarization. By increasing the amount of transmission information, it is possible to perform more efficient transmission than the conventional method using only H / V polarized waves independently.

  At this time, a plurality of signal points are simultaneously arranged in the H / V space as shown in FIG. Signal points in this method are formed by combining values mapped to the respective polarization components H / V polarization before combination.

  In FIG. 3A, the non-orthogonal polarization component is only S polarization, but more generally, a plurality of non-orthogonal polarization components can be assumed.

Here, assuming that the complex signal point of the modulation scheme assigned to the nth polarization Sn is rn _{, a} , the signal point arrangement points Ha, Va on the H / V polarization after the polarization synthesis are given by the following equations. It is done.

However, a is the symbol number ^{(1 ≦ a ≦ 2 b)} , b is the number of bits of the or one symbol, N is the polarized wave number (the number of multiplexing), m _sn the polarization S _n amplitude, [psi _Sn is polarized Let S _{n be} the polarization angle (relative to H polarization).

  FIG. 3 (b) shows the H when the S-polarized wave that is non-orthogonal to the H / V-polarized wave is additionally combined, assuming QPSK modulation for each of the H-polarized wave, V-polarized wave, and S-polarized wave The signal point arrangement of polarization and V polarization is shown.

That is, when the number of polarization multiplexing in the non-orthogonal polarization multiplexing system is 3, and the number of modulation bits allocated to each polarization is 2 bits (QPSK), the information bit i is represented by rn _{, a} as shown in the following equation. (N) and q (n) are assigned, and mapping is performed on the signal points H _a and V _a represented by the equations (1) and (2).

However, i (n) = (0, 1), q (n) = (0, 1).

Under this setting condition, the amplitude m _s1 (= 1) and the polarization angle ψ _S1 (= 0 °) of the reference polarization S ₁ (H polarization) are fixed, and the amplitude m _s2 of S ₂ / S ₃ , It is assumed that the polarization angles ψ _S2 and ψ _S3 with respect to m _s3 and the polarization S ₁ are changed.

As an example, when m _s2 = 1 and ψ _S2 = 90 °, the combination of parameters that maximizes the minimum Euclidean distance when m _s3 and ψ _S3 are changed is (m _s1 , m _s2 , m _s3 ) = (1: 1: 0.707), (ψ _S1 , ψ _S2 , ψ _S3 ) = (0 °: 90 °: 45 °). This is the arrangement shown in FIG.

  In this case, in the H-polarization space or the V-polarization space, one signal point (symbol) corresponds to 6-bit information, and is degenerate fourfold. However, by combining information of signal points of H polarization and V polarization, information bits to be expressed can be specified by solving the degeneracy.

(Multi-polarization spatial modulation system)
In the multi-polarization spatial modulation method, the combined vector expressed by the I / Q component of the carrier wave and the polarization angle φ _l is regarded as one arrangement point in the H / V space, and the modulation multi-value number is increased. Enables more efficient transmission than conventional methods.

  FIG. 4 is a conceptual diagram showing an outline of such a multi-polarization spatial modulation system.

  As shown in FIG. 4A, one signal point is simultaneously arranged on the H / V space. That is, in the conventional method, the signal points are arranged such that the H space and the V space are independent from each other. In the multi-polarization spatial modulation system, signal points are arranged in a space spanned by H and V by controlling the polarization angle.

Here, when a reference (assigned to I / Q components of the carrier wave) the complex signal points of the modulation scheme and r _c, constellation points H _a on H / V polarized wave in this manner, V _a, the following It is given by the formula.

Where c is the symbol number of the reference modulation method (1 ≦ c ≦ 2 ^d ), d is the number of bits of the reference modulation method, angle φ _l is the polarization angle (1 ≦ l ≦ 2 ^e ), and e is The number of bits assigned to the polarization angle.

In the multi-polarization spatial modulation method, when the modulation method used as a reference is QPSK (2 bits) and 1 bit is assigned to the polarization angle, information bits i, q, and k are assigned to r _c and φ as shown in the following equation. , Mapping is performed on the signal points Ha and Va expressed by the equations (4) and (5).

However, i = (0, 1), q = (0, 1), k = (0, 1), and 0 ° ≦ ψ ≦ 180 °.

  Under this setting condition, when the polarization angle at which the minimum Euclidean distance is maximized when the polarization angle ψ is changed from 0 ° to 180 ° is obtained, it is 45 ° or 135 °.

  This is the arrangement shown in FIG.

  For example, in FIG. 4B, if ψ = 45 °, each signal point (symbol) corresponds to 3-bit information and is degenerate in a double manner. However, by combining information of signal points of H polarization and V polarization, information bits to be expressed can be specified by solving the degeneracy.

  As explained above, the “non-orthogonal polarization multiplexing method” and the “multi-polarization spatial modulation method” use the following properties in order to improve the frequency utilization efficiency over the conventional polarization multiplexing method. In common.

  That is, the conventional orthogonal polarization multiplexing method using V polarization and H polarization defines signal points using multilevel modulation in V polarization and H polarization which are physically independent from each other. . As a result, the efficiency is doubled as compared with the case where only the V polarization or only the H polarization is used.

  On the other hand, the “non-orthogonal polarization multiplexing method” or “multi-polarization spatial modulation method” is not limited to V polarization and H polarization, but also to a space constituted by V polarization and H polarization. Also, by assigning signal points, frequency utilization efficiency higher than that of the conventional method is achieved.

  Therefore, in the following, when such a method for assigning signal points to a space composed of V polarization and H polarization is generically referred to as a “multi-polarization spatial multiplexing transmission method”.

  As described above, FIGS. 3 and 4 show a case where the arrangement of signal points is determined so that the minimum Euclidean distance between the signal points is maximized.

  However, a determination error between symbols having a small Euclidean distance and a large Hamming distance, that is, it is difficult to correct an error, is a major factor in BER (Bit Error Rate) characteristic deterioration.

  Therefore, in this embodiment, the signal point arrangement that minimizes the evaluation formula (8) that combines the Hamming distance Hdist and the Euclidean distance Edist is set as the optimum arrangement. By using this evaluation formula (8), it is possible to easily derive a signal point arrangement that minimizes the influence of a symbol (Hdist: large, Edist: small) that is a main factor of BER characteristic deterioration.

Here, M is a set arbitrarily selected from n (1 ≦ n ≦ 2 ^N ), m is an index of the set M, and n is a symbol index (1 ≦ n ≦ 2 ^N) on the H / V polarization plane. N indicates the number of bits per symbol on the H / V polarization.

  Note that the set M in the above formula (8) may be arbitrarily selected (for example, all symbols n, or symbols having a value of Hdist (m) / Edist (m) from the minimum to the (arbitrary) kth). Assume that the evaluation target can be selected.

The evaluation formula may be a function of the Euclidean distance and the Hamming distance, and may be a maximum value in a set M of functions that monotonously increase as the Euclidean distance decreases and increase monotonously as the Hamming distance increases. For example, it is not limited to the formula (8). The signal point arrangement is optimized so as to minimize such an evaluation formula.
(Example applied to non-orthogonal polarization multiplexing)
Hereinafter, a case where the signal point arrangement based on the evaluation formula as described above is applied to the non-orthogonal polarization multiplexing scheme will be described. However, the optimization method of the present embodiment is not limited to such a case, and can be applied to, for example, a multi-polarization spatial modulation system.

Therefore, here, a signal in which 2 bits are allocated to signal points on the IQ plane for each of three polarizations (S _{1 to} S ₃ ) that are not necessarily orthogonal is synthesized as shown in Equation (9), and (6 bits per symbol) It is assumed that the combined signal point arrangement on the H / V polarization is formed by mapping on the IQ plane on the H / V polarization (expressed by

Here, H is an IQ component (complex number) of horizontal polarization, V is an IQ component (complex number) of vertical polarization, and α _{1 to} α ₃ and β _{1 to} β ₃ are the amplitude, phase, and polarization of each polarization. It is a parameter for controlling the angle, and takes a value in the range of ± 1 for each real part and imaginary part. As optimization conditions, the horizontal and vertical polarizations are perfectly synchronized and no interference occurs, and the arrangement is normalized so that the total power between H / V polarizations is 1.

  Further, when the H / V power balance is not guaranteed, a power amplifier for high power is required on the transmission side (because it is necessary to adjust to a large power when the magnitude relationship of H / V power is indefinite). When the power of each polarization of the optimally arranged H / V is different, adjustment is made to the signal point arrangement of H / V equal power by multiplying the polarization rotation matrix (Equation 10) of an appropriate angle θ. Note that there is no difference in BER characteristics between the arrangements before and after power equalization.

FIG. 5 is a diagram illustrating a result of optimization of signal point arrangement according to the present embodiment.

That is, in FIG. 5, which can be generated when the respective real part imaginary part of the parameters (alpha ₁ to? ₃ and β ₁ ~β ₃₎ of Equation (9), was changed by 0.00001 in the range of ± 1 With respect to the signal point arrangement, the result of searching for the optimum arrangement that minimizes the maximum value of Hdist (m) / Edist (m) for all 2 ^N symbols in Expression (8) is shown.

  FIG. 6 is a signal point arrangement shown as arrangement A in FIG.

  That is, the arrangement A is a signal point arrangement that maximizes the minimum Euclidean distance as a comparison target.

  On the other hand, FIG. 7 is a signal point arrangement shown as arrangement B in FIG.

  That is, as shown in FIG. 7A, the arrangement B is an optimized arrangement that minimizes the evaluation value of the equation (8), and FIG. 7B shows the arrangement of FIG. This is the arrangement after the H / V equal power processing.

  The relationship between each symbol and the signal point arrangement on the I / Q plane of the H / V polarization calculated as shown in FIG. 7B is the I / Q mapping data storage unit 106 or I / Q described above. It is assumed that it is stored in the mapping data storage unit 210.

  FIG. 8 is a flowchart for explaining processing in transmitter 1000 and receiver 2000.

  Referring to FIG. 8, first, transmitter 1000 performs error correction coding processing of a transmission signal (S100).

  Subsequently, the transmitter 1000 performs optimization as described above, and sends signals to the V polarization space and the H polarization space based on the I / Q mapping data stored in the I / Q mapping data storage unit 106. Mapping is performed (S102).

  The transmitter 1000 further modulates (orthogonally modulates) the signal in the V polarization space and the H polarization space (S104), performs D / A conversion, and then transmits the V polarization and the H polarization from the antenna. A signal is transmitted (S106).

  On the other hand, the receiver 2000 receives V polarization and H polarization by the antenna (S110), and after A / D conversion, performs quadrature detection for each of the V polarization component and the H polarization component (S112). .

  Furthermore, the receiver 2000 is optimized as described above, and performs maximum likelihood estimation in the V polarization space and the H polarization space based on the I / Q mapping data stored in the I / Q mapping data storage unit 210. (S114), and error correction decoding processing is performed to obtain received symbols (S116).

  FIG. 9 is a diagram showing a result of confirming the bit error rate in each signal point arrangement of FIGS. 6 and 7B (after V / H power adjustment) by computer simulation.

  Note that a convolutional code having a coding rate of 1/2 and a constraint length of 7 is used for error correction coding, and a hard decision Viterbi algorithm and a soft decision Viterbi algorithm are used for error correction decoding.

  As shown in FIG. 9, the error rate of the arrangement B (FIG. 7B) optimized in the present embodiment is about 0.6 dB in the BER = 1E-04 region in the case of Hard Viterbi, and in the case of Soft Viterbi. Thus, it is improved by about 1.9 dB in the BER = 1E-04 region.

  Thus, according to the signal point arrangement of the present embodiment, it is possible to easily derive an optimal signal point arrangement having an excellent bit error rate for the multi-polarization spatial multiplexing transmission system.

  Embodiment disclosed this time is an illustration of the structure for implementing this invention concretely, Comprising: The technical scope of this invention is not restrict | limited. The technical scope of the present invention is shown not by the description of the embodiment but by the scope of the claims, and includes modifications within the wording and equivalent meanings of the scope of the claims. Is intended.

  100 error correction coding processing unit, 102 S / P conversion unit, 104 V / H mapping processing unit, 106, 210 I / Q mapping data storage unit, 108a, 108b orthogonal modulation unit, 110a, 110b D / A conversion unit, 112a, 112b Transmission filter processing unit, 114a, 200a Vertical polarization antenna, 114b, 200b Horizontal polarization antenna, 202a, 202b Reception filter processing unit, 204a, 204b A / D conversion unit, 206a, 206b Quadrature detection unit, 208 Likelihood determination processing unit, 212 P / S conversion unit, 214 error correction decoding processing unit, 1000 transmitter, 2000 receiver.

Claims (10)

A wireless communication system that performs transmission / reception by multi-polarization spatial multiplexing transmission that assigns signal points in vertical polarization, horizontal polarization, and space constituted by vertical polarization and horizontal polarization,
With a transmitter and receiver,
The transmitter is
A transmitting antenna;
An error correction coding processing unit for performing error correction coding processing on a transmission symbol;
A first storage unit,
The first storage unit is a function of a Euclidean distance and a Hamming distance, and is a predetermined transmission symbol of a function that monotonously increases as the Euclidean distance decreases and increases monotonously as the Hamming distance increases. Store the constellation calculated to minimize the maximum value in the set of
Based on the information stored in the first storage unit, in the multi-polarization spatial multiplexing transmission, the output of the error correction coding processing unit is converted to the in-phase component and the quadrature phase in the vertical polarization and the horizontal polarization. A mapping processor assigned in the component plane;
Based on the processing result of the mapping processing unit, performing orthogonal modulation for vertical polarization and horizontal polarization, and further including a transmission unit that transmits from the transmission antenna,
The receiver
A receiving antenna;
A receiver that performs quadrature detection for the vertically polarized wave and the horizontally polarized wave, respectively, for the signal received by the receiving antenna;
A second storage unit that stores information corresponding to the signal point arrangement stored in the first storage unit;
Based on the information stored in the second storage unit, in the multi-polarization spatial multiplexing transmission, a maximum likelihood determination processing unit for performing maximum likelihood determination for vertical polarization and horizontal polarization,
A wireless communication system including an error correction decoding processing unit for executing an error correction decoding process based on a determination result of the maximum likelihood determination processing unit.   The wireless communication system according to claim 1, wherein the function is a ratio of a Hamming distance to an Euclidean distance in the predetermined set of transmission symbols.   The wireless communication system according to claim 1 or 2, wherein the multi-polarization spatial multiplexing transmission is a non-orthogonal polarization multiplexing system.   The wireless communication system according to claim 1, wherein the multi-polarization spatial multiplexing transmission is a multi-polarization spatial modulation system. A wireless communication device that performs transmission by multi-polarization spatial multiplexing transmission that assigns signal points in vertical polarization, horizontal polarization, and space constituted by vertical polarization and horizontal polarization,
A transmitting antenna;
An error correction coding processing unit for performing error correction coding processing on a transmission symbol;
A storage unit,
The storage unit is a function of a Euclidean distance and a Hamming distance, and increases in a monotonous manner as the Euclidean distance decreases, and increases in a monotonous manner as the Hamming distance increases. Store the calculated signal point arrangement to minimize the maximum value,
Based on the information stored in the storage unit, in the multi-polarization spatial multiplexing transmission, the output of the error correction coding processing unit is output in the in-phase and quadrature component planes in the vertical polarization and the horizontal polarization. A mapping processing unit to be assigned to
A wireless communication apparatus further comprising: a transmission unit that performs orthogonal modulation on vertical polarization and horizontal polarization based on a processing result of the mapping processing unit, and transmits the result from the transmission antenna. A wireless communication device that performs reception by multi-polarization spatial multiplexing transmission that assigns signal points in vertical polarization, horizontal polarization, and space constituted by vertical polarization and horizontal polarization,
A receiving antenna;
A receiver that performs quadrature detection for the vertically polarized wave and the horizontally polarized wave, respectively, for the signal received by the receiving antenna;
A storage unit,
The storage unit is a function of a Euclidean distance and a Hamming distance, and increases in a monotonous manner as the Euclidean distance decreases, and increases in a monotonous manner as the Hamming distance increases. Store the calculated signal point arrangement to minimize the maximum value,
Based on the information stored in the storage unit, in the multi-polarization spatial multiplexing transmission, maximum likelihood determination processing unit for performing maximum likelihood determination for vertical polarization and horizontal polarization,
A wireless communication device further comprising: an error correction decoding processing unit for executing an error correction decoding process based on a determination result of the maximum likelihood determination processing unit.   The wireless communication apparatus according to claim 5 or 6, wherein the function is a ratio of a Hamming distance to an Euclidean distance in the predetermined set of transmission symbols.   The wireless communication apparatus according to claim 5 or 6, wherein the multi-polarization spatial multiplexing transmission is a non-orthogonal polarization multiplexing system.   The radio communication apparatus according to claim 5 or 6, wherein the multi-polarization spatial multiplexing transmission is a multi-polarization spatial modulation system. A wireless communication method for performing transmission / reception by multi-polarization spatial multiplexing transmission in which signal points are allocated in vertical polarization, horizontal polarization, and space constituted by vertical polarization and horizontal polarization,
A transmitter performing error correction coding processing on the transmitted symbols;
A transmitter that is a function of Euclidean distance and Hamming distance, and that increases monotonically as the Euclidean distance decreases and increases monotonically as the Hamming distance increases; Based on the signal point arrangement calculated so as to minimize the value, in the multi-polarization spatial multiplexing transmission, the error correction coding processing result is obtained as an in-phase component and a quadrature in the vertical polarization and in the horizontal polarization. Mapping to assign in the phase component plane;
The transmitter performs orthogonal modulation for vertical polarization and horizontal polarization based on the result of the mapping process, and transmits from the transmission antenna;
A receiver performing quadrature detection for the vertical polarization and the horizontal polarization, respectively, for the received signal;
The receiver performs maximum likelihood determination for vertical polarization and horizontal polarization in the multi-polarization spatial multiplexing transmission based on the signal point arrangement in the transmitter; and
And a receiver that executes error correction decoding processing based on the determination result of the maximum likelihood determination.