JP2009033666A - Radio communication apparatus, radio transmission method and radio reception method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus capable of estimating characteristics of a wireless transmission line for each antenna from a plurality of known signals transmitted by a plurality of the antennas. <P>SOLUTION: A first known symbol and a second known symbol are multiplied by a first weight sequence, and the first known symbol and the second known symbol are multiplied by a second weight sequence orthogonal with the first weight sequence to generate a first frame including the first and the second known symbols multiplied by the first weight sequence and a second frame including the first and the second known symbols multiplied by the second weight sequence, the first frame is transmitted using a first antenna, and the second frame is transmitted using a second antenna. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio communication apparatus that applies transmission diversity to a known signal.

  In a wireless communication system, it is necessary to synchronize transmission / reception timing and the like between a wireless transmission device and a wireless reception device. For this reason, the wireless transmission device transmits a signal having a predetermined transmission waveform (hereinafter referred to as a known signal) periodically or at the start of communication, and the wireless reception device needs to detect the known signal. Further, since the signal transmitted by the wireless transmission device is performed in accordance with a predetermined format called a wireless frame or the like, a plurality of timings depending on the configuration of the wireless frame are synchronized. For example, the boundary of each of a symbol that is a minimum unit of a radio frame, a slot configured by a plurality of symbols, and a frame configured by a plurality of slots may be detected. Furthermore, together with timing synchronization, a wireless transmission device that has transmitted a known signal may be specified at the same time (see, for example, Non-Patent Document 1).

  In addition, since various synchronization processes are performed in the wireless reception device as described above, a plurality of known signals may be defined for the purpose of efficiently performing the processes (see, for example, Non-Patent Document 2).

  In general, since the synchronization processing described above is performed prior to the start of communication, it is desirable that the detection accuracy in the wireless reception device be high, and in particular, when the wireless transmission device periodically transmits known signals, a plurality of wireless receptions are performed. Since the device receives the known signal, it is desirable that the known signal can be detected even by a wireless reception device that is located far from the wireless transmission device. For this reason, when the wireless transmission device has a plurality of antennas, a technique called transmission diversity may be applied for the purpose of improving detection accuracy in the wireless reception device.

For example, there is a technique in which known signals transmitted from a plurality of antennas are multiplied by a predetermined weight for each antenna and the weight is changed at a predetermined cycle (for example, Non-Patent Document 3). reference).
Physical layer procedures (FDD), 3GPP, TS25.214, v7.3.0, p.56 Physical channels and mapping of transport channels onto physical channels (FDD), 3GPP, TS25.211, v7.0.0, p.33 3GPP, TSGRAN WG1, R1-070746, ETRI, “Comparison of SCH diversity schemes”, St. Louis, USA, February, 2007

  As described above, a signal for synchronizing transmission / reception timing or the like is a predetermined known signal. Therefore, the signal can be used not only for synchronization in the radio reception apparatus but also for estimating the characteristics of the radio propagation path, for example. In this case, when the wireless transmission device includes a plurality of antennas, it is desirable that the characteristics of the wireless propagation path for each antenna can be estimated.

  By the way, in the above-described prior art, two known signals are defined, and the same weight is multiplied to each known signal in any period. In this case, it is difficult to estimate the characteristics of the radio propagation path for each antenna using any known signal.

  Therefore, in view of the above problems, the present invention provides a plurality of known signals when the wireless transmission device includes a plurality of antennas and transmission diversity is applied to a plurality of known signals whose transmission waveforms are predetermined. An object of the present invention is to provide a wireless communication device, a wireless transmission method, and a wireless reception method that can be used to estimate the characteristics of a wireless propagation path for each antenna.

  (1) A wireless communication device including first and second antennas generates a first known symbol and a second known symbol, and generates a first known symbol and a second known symbol, 1 weight sequence is multiplied, the first known symbol and the second known symbol are multiplied by a second weight sequence orthogonal to the first weight sequence, and the first weight sequence is multiplied. Generating a first frame including the first and second known symbols and a second frame including the first and second known symbols multiplied by the second weight sequence, The first frame is transmitted using an antenna, and the second frame is transmitted using the second antenna.

  (2) The receiving apparatus may be configured to multiply the first known symbol and the second known symbol multiplied by the first weight sequence, and the second weight sequence orthogonal to the first weight sequence. When the signal including the known symbol and the second known symbol is received, the first known symbol and the second known symbol are extracted from the signal, and the first known symbol extracted is extracted from the first known symbol. 2 by adding and subtracting the result of multiplying the complex conjugate of the replica of the known symbol and the result of multiplying the extracted second known symbol by the complex conjugate of the replica of the second known symbol. Estimate the characteristics of the radio transmission path for each of the two antennas.

  The characteristics of the radio transmission path for each antenna can be estimated from a plurality of known signals transmitted by a plurality of antennas.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of signals used in the wireless communication system according to the present embodiment. FIG. 1A shows a signal used in a multi-carrier wireless communication system represented by OFDM (Orthogonal Frequency Division Multiplexing), and FIG. 1B shows a signal used in a single-carrier wireless communication system to which a cyclic prefix is added. Signal. In any case, since a cyclic prefix is assigned, the wireless reception device is characterized in that distortion of the wireless propagation path is compensated in the frequency domain.

  FIG. 2 shows an example of a frame format of the wireless transmission signal according to the present embodiment. FIG. 2 shows an example of a frame format suitable when the wireless communication system to which the present embodiment is applied is the multicarrier wireless communication system shown in FIG.

  According to FIG. 2, a slot is composed of a plurality of symbols, and a frame is composed of a plurality of slots. In addition, a first known symbol, a second known symbol, and a data symbol are defined as symbol types. Further, the first known symbol and the second known symbol are included only in a predetermined slot in the frame and are arranged in adjacent symbols.

  In FIG. 2, two types of known symbols are defined, but in the present embodiment, N (N ≧ 2) types of known symbols can be defined without being limited to two types. In addition, two slots including the first known symbol and the second known symbol are defined in one frame, but in this embodiment, an arbitrary number can be defined. Furthermore, the position of the slot including the first known symbol and the second known symbol in the frame and the position of the first known symbol and the second known symbol in the slot can be arbitrarily defined.

  In the example of FIG. 2, the first known symbol and the second known symbol are arranged in adjacent symbols in a predetermined slot in the frame. However, as shown in FIG. 3, they need to be arranged adjacent to each other. There is no. However, although details will be described later, the effects of the present invention can be fully enjoyed when the first known symbol and the second known symbol are arranged at close positions.

[Transmitter]
FIG. 4 shows a configuration example of the wireless transmission device according to the present embodiment. 4 includes an antenna 1 (1a, 1b), a radio processing unit 2 (2a, 2b), a CP adding unit 3 (3a, 3b), a multiplexing unit 4, a first weight multiplication unit 5a, and a second weight. A multiplier 5b, a transmission data symbol generator 6, a first known symbol generator 7, and a second known symbol generator 8 are provided. The antenna 1, the radio processing unit 2, and the CP adding unit 3 have the same number as the number of antennas. In the example of FIG. 4, the number of antennas is described as “2” (hereinafter referred to as the first transmission antenna 1a and the second transmission antenna 1b). In addition, the number N of known symbols is “2”.

  Next, the operation of the wireless transmission device in FIG. 4 will be described. The transmission data is input to the transmission data symbol generation unit 6. The transmission data symbol generation unit 6 adds a predetermined error detection code such as CRC (Cyclic Redundancy Check) to the input data, performs error correction coding with a predetermined coding method and coding rate, and a predetermined modulation method. In addition to performing modulation according to the above, processing such as diversity encoding is performed as necessary, and the result is input to the multiplexing unit 4 as a transmission data symbol.

  The first known symbol generator 7 generates a first known symbol having a predetermined known signal waveform, and inputs the first known symbol to the first weight multiplier 5a and the second weight multiplier 5b. Similarly, the second known symbol generator 8 generates a second known symbol having a predetermined known signal waveform, and inputs the second known symbol to the first weight multiplier 5a and the second weight multiplier 5b.

  The first weight multiplier 5a corresponds to the first transmission antenna 1a, and multiplies each of the first known symbol and the second known symbol by a predetermined weight to multiplex the unit 4. Enter.

  The second weight multiplication unit 5b corresponds to the second transmission antenna 1b, and multiplies each of the first known symbol and the second known symbol by a predetermined weight to multiplex unit 4. Enter.

  The multiplexing unit 4 multiplexes the input transmission data symbol, the first known symbol, and the second known symbol, for example, in accordance with a predetermined frame format as shown in FIG. 2 or FIG. Are output to the CP adding section 3 (3a, 3b) corresponding to each antenna.

  The CP adding unit 3 (3a, 3b) adds a cyclic prefix (CP) for each symbol to the input frame signal and inputs it to the radio processing unit 2 (2a, 2b). The radio processing unit 2 (2a, 2b) generates a radio signal by predetermined radio processing such as D / A conversion, quadrature modulation, up-conversion, band limitation, power amplification, and the like, and the radio signal is transmitted to the antenna 1 (1a, 1b). ).

  Here, referring to FIG. 5, the first and second weight multipliers 100a and 100b in the prior art (corresponding to the first weight multiplier 5a and the second weight multiplier 5b in FIG. 4), respectively. An operation example will be described. Here, following the configuration of the transmission apparatus in FIG. 4, the transmission apparatus including the first and second weight multiplication units in FIG. 5 includes two transmission antennas, and the number N of known symbols is “2”. It is said.

  The first weight multiplication unit 100a of FIG. 5 includes a weight storage unit 101a that stores predetermined weights, and is the same for each of the input first known symbol and second known symbol. Multiply the weight of. Similarly, the second weight multiplication unit 100b includes a weight storage unit 101b that stores predetermined weights, and is the same for each of the input first known symbol and second known symbol. Multiply the weight of. Here, the weight changes for each slot in which the first known symbol and the second known symbol are transmitted, and the repetition period is “4”. That is, with a period of 4 slots, a different weight is multiplied for each slot.

  Here, a set of weights multiplied by each known symbol transmitted by each antenna in each cycle is referred to as a set. That is, set = {weight to multiply the first known symbol transmitted by the first antenna, weight to multiply the second known symbol transmitted by the first antenna, and first known to transmit by the second antenna Weight multiplied by symbol, Weight multiplied by second known symbol transmitted by second antenna}.

  In the example shown in FIG. 5, there are four types of sets from the following set 1 to set 4.

Set 1 = {exp (j * 0), exp (j * 0), exp (j * 0), exp (j * 0)}
Set 2 = {exp (j * 0), exp (j * 0), exp (j * π / 2), exp (j * π / 2)}
Set 3 = {exp (j * 0), exp (j * 0), exp (j * π), exp (j * π)}
Set 4 = {exp (j * 0), exp (j * 0), exp (j * 3π / 2), exp (j * 3π / 2)}
Also, the weight by which the Nth known symbol transmitted from the Mth antenna in the Lth set is multiplied by _Wlmn, and each known symbol transmitted from the Mth transmitting antenna in the Lth set is multiplied. If the combination of weights to be performed is a weight vector (weight series) V _lm , L = 1, 2, 3, 4, M = 1, 2, N = 1, 2 in the example shown in FIG. V ₁₁ = (W ₁₁₁ , W ₁₁₂ ) = (exp (j * 0), exp (j * 0))
V ₁₂ = (W ₁₂₁ , W ₁₂₂ ) = (exp (j * 0), exp (j * 0))
V ₂₁ = (W ₂₁₁ , W ₂₁₂ ) = (exp (j * 0), exp (j * 0))
V ₂₂ = (W ₂₂₁ , W ₂₂₂ ) = (exp (j * π / 2), exp (j * π / 2))
V ₃₁ = (W ₃₁₁ , W ₃₁₂ ) = (exp (j * 0), exp (j * 0))
V ₃₂ = (W ₃₂₁ , W ₃₂₂ ) = (exp (j * π), exp (j * π))
V ₄₁ = (W ₄₁₁ , W ₄₁₂ ) = (exp (j * 0), exp (j * 0))
V ₄₂ = (W ₄₂₁ , W ₄₂₂ ) = (exp (j * 3π / 2), exp (j * 3π / 2))
It can be expressed as.

  Next, the configuration and operation of the first and second weight multipliers 5a and 5b in FIG. 4 will be described with reference to FIG. Here, according to the configuration of the transmission apparatus of FIG. 4, the transmission apparatus is provided with two transmission antennas, and the number N of known symbols is “2”. Furthermore, the weight to be multiplied changes for each slot, and the repetition period is set to “2”.

  In FIG. 6, the first weight multiplication unit 5 a includes a first weight storage unit 500 a 1 that stores a predetermined weight for the first known symbol and a predetermined value for the second known symbol. And a second weight storage unit 500a2 for storing weights.

  The multiplier 501a1 multiplies the input first known symbol by the weight stored in the first weight storage unit 500a1, and the multiplier 501a2 performs the input second known symbol. Multiply the weight stored in the second weight storage unit 500a2.

  Similarly, the second weight multiplication unit 5b includes a first weight storage unit 500b1 that stores a predetermined weight for the first known symbol, and a predetermined weight for the second known symbol. And a second weight storage unit 500b2.

  The multiplier 501b1 multiplies the input first known symbol by the weight stored in the first weight storage unit 500b1, and the multiplier 501b2 performs the input second known symbol. Multiply the weight stored in the second weight storage unit 500b2.

  In the example shown in FIG. 6, the first known symbol and the second known symbol transmitted by the first transmitting antenna 1a are multiplied by one set of the first known symbol and the second known symbol. The weights to be used are exp (j * 0) and exp (j * 0), respectively, and the weights to be multiplied with respect to the first known symbol and the second known symbol transmitted by the second transmitting antenna 1b are: They are exp (j * 0) and exp (j * π), respectively.

  Further, in a set different from the above, the weights to be multiplied for the first known symbol and the second known symbol transmitted by the first transmitting antenna 1a are exp (j * 0) and exp (j *, respectively). 0), and the weights for multiplying the first known symbol and the second known symbol transmitted by the second transmitting antenna 1b are exp (j * π) and exp (j * 0), respectively. ing.

  That is, in the example shown in FIG. 6, the following set 1 and set 2 exist.

Set 1 = {exp (j * 0), exp (j * 0), exp (j * 0), exp (j * π)}
Set 2 = {exp (j * 0), exp (j * 0), exp (j * π), exp (j * 0)}
Therefore, since the weight vector V _lm in the example shown in FIG. 6 is L = 1, 2, M = 1, 2, N = 1, 2, V ₁₁ = (W ₁₁₁ , W ₁₁₂ ) = (exp ( j * 0), exp (j * 0))
V ₁₂ = (W ₁₂₁ , W ₁₂₂ ) = (exp (j * 0), exp (j * π))
V ₂₁ = (W ₂₁₁ , W ₂₁₂ ) = (exp (j * 0), exp (j * 0))
V ₂₂ = (W ₂₂₁ , W ₂₂₂ ) = (exp (j * π), exp (j * 0))
It can be expressed as.

  Here, differences between the conventional example shown in FIG. 5 and the present embodiment shown in FIG. 6 will be described. In the conventional example shown in FIG. 5, the weight vector of each transmitting antenna in each set (each period) is the same weight. On the other hand, in FIG. 6, the weight vector of each transmission antenna in each set (each cycle) includes different weights for at least one transmission antenna weight vector, and the weight vector in each set (each cycle). Is in an orthogonal relationship.

That is, when focusing on the set 1, the inner product of the weight vector V ₁₁ and the weight vector V ₁₂ is
exp (j * 0) × exp (j * 0)) + exp (j * 0) × exp (j * π)
= 1 × 1 + 1 × (−1) = 0
It becomes. Similarly for Set 2,
exp (j * 0) × exp (j * 0)) + exp (j * π) × exp (j * 0)
= 1 × 1 + (− 1) × 1 = 0
_{It becomes.}
In FIG. 6, the weights included in the weight vector corresponding to the first transmission antenna 1a have the same value. Therefore, in such a case, as shown in FIG. 6, the first weight multiplication unit 5a does not need to include the weight storage units 501a1 and 501a2 for each known symbol. For example, as shown in FIG. The configuration and the operation may be provided with only (for example, only the first weight storage unit 501a1).

  Next, another configuration and operation of the first and second weight multipliers 5a and 5b in FIG. 4 will be described with reference to FIG. Here, according to the configuration of the transmission apparatus of FIG. 4, the transmission apparatus is provided with two transmission antennas, and the number N of known symbols is “2”. Furthermore, the weight to be multiplied changes for each slot, and the repetition period is “4”. In FIG. 8, the same parts as those in FIG. 6 are denoted by the same reference numerals, and different parts will be described.

  The difference from FIG. 6 is that the repetition period is set to “4”. Therefore, in each period, the set of weights to be multiplied to each known symbol transmitted by each antenna is set as follows: There are four types.

Set 1 = {exp (j * 0), exp (j * 0), exp (j * 0), exp (j * π)}
Set 2 = {exp (j * 0), exp (j * 0), exp (j * π / 2), exp (j * 3π / 2)}
Set 3 = {exp (j * 0), exp (j * 0), exp (j * π), exp (j * 0)}
Set 4 = {exp (j * 0), exp (j * 0), exp (j * 3π / 2), exp (j * π / 2)}
Therefore, the weight vector V _lm is different from the example shown in FIG. Since the weight vector V _lm in the example shown in FIG. 8 is L = 1, 2, 3, 4, M = 1, 2 and N = 1, 2, V ₁₁ = (W ₁₁₁ , W ₁₁₂ ) = ( exp (j * 0), exp (j * 0))
V ₁₂ = (W ₁₂₁ , W ₁₂₂ ) = (exp (j * 0), exp (j * π))
V ₂₁ = (W ₂₁₁ , W ₂₁₂ ) = (exp (j * 0), exp (j * 0))
V ₂₂ = (W ₂₂₁ , W ₂₂₂ ) = (exp (j * π / 2), exp (j * 3π / 2))
V ₃₁ = (W ₃₁₁ , W ₃₁₂ ) = (exp (j * 0), exp (j * 0))
V ₃₂ = (W ₃₂₁ , W ₃₂₂ ) = (exp (j * π), exp (j * 0))
V ₄₁ = (W ₄₁₁ , W ₄₁₂ ) = (exp (j * 0), exp (j * 0))
V ₄₂ = (W ₄₂₁ , W ₄₂₂ ) = (exp (j * 3π / 2), exp (j * π / 2))
It can be expressed as.

  Also in this case, the weight vector of each transmission antenna in each set (period) includes different weights as the weight vector of at least one transmission antenna, and the weight vectors in each set (period) are in an orthogonal relationship. I understand that there is.

  As will be described later, in order to estimate the characteristics of the radio propagation path for each antenna, when the number of antennas is “2”, the number of known symbols needs to be “2” or more. That is, as described above, the number of known symbols multiplied by the weight vector needs to be equal to or more than the number of antennas.

"Receiver"
FIG. 9 shows a configuration example of the wireless reception apparatus according to this embodiment. 9 includes an antenna 31, a radio processing unit 32, a synchronization detection unit 33, a CP removal unit 34, an S / P conversion unit 35, a time / frequency conversion unit 36, a separation unit 37, a P / S conversion unit 38, A data symbol demodulator 39 and a transmission path estimator 40 are provided. In FIG. 9, the number of reception antennas is assumed to be “1”.

  Next, the operation of the receiving apparatus in FIG. 9 will be described. The radio signal received by the antenna 31 is subjected to predetermined radio processing such as power amplification, band limitation, down-conversion, quadrature demodulation, and A / D conversion by the radio processing unit 32, and is converted into a received digital signal to detect synchronization. Input to the unit 33 and the CP removal unit 34.

  The synchronization detection unit 33 performs synchronization processing such as detection of symbols, slots, and frame timing using the first known symbol and the second known symbol, and the result (particularly symbol timing) is sent to the CP removal unit 34. Notice. Furthermore, the first known symbol and the second known symbol used for detection belong to, for example, which set (of the two or four sets described above) belongs, and the detection result (set identification) Information) to the transmission path estimation unit 40.

  The CP removal unit 34 removes the cyclic prefix based on the notified symbol timing and inputs the cyclic prefix to the S / P conversion unit 35. The S / P converter 35 performs serial / parallel conversion on the input received digital signal in units of a predetermined number of samples, and inputs it to the time / frequency converter 36. The time / frequency conversion unit 36 converts a time domain digital signal into a frequency domain digital signal by, for example, DFT (Discrete Fourier Transform) or FFT (Fast Fourier Transform).

  The separation unit 37 separates the input digital signal into a transmission data symbol, a first known symbol, and a second known symbol, for example, according to a predetermined frame format described using FIG. 2 or FIG. If it is a symbol, it is output to the P / S converter 38, and if it is a first known symbol and a second known symbol, it is output to the transmission path estimator 40.

  The P / S conversion unit 38 performs parallel / serial conversion on the input digital signal in units of a predetermined number of samples and inputs the digital signal to the data symbol demodulation unit 39.

  The transmission path estimation unit 40 estimates the radio transmission path for each antenna of the transmission apparatus using the input first known symbol and second known symbol, and inputs the result to the data symbol demodulation unit 39. The data symbol demodulator 39 performs processing such as diversity decoding on the input transmission data symbol as necessary, and demodulates the input transmission data symbol by a demodulation method based on a predetermined modulation method. The transmission data is decoded by a decoding method based on the conversion rate. Further, error detection is performed using an error detection code, and an error detection result is output.

  Note that the transmission path estimation unit 40 performs the transmission path estimation processing using the first known symbol and the second known symbol used for the synchronization processing, but general frame formats include those shown in FIGS. In addition to the symbol types shown in FIG. 3, a pilot symbol for performing transmission path estimation processing in the receiving apparatus is included, and the transmission path estimation unit 40 also performs transmission path estimation processing using the pilot symbol. Can do.

  FIG. 10 illustrates a configuration example of the transmission path estimation unit 40 illustrated in FIG. Here, a case where the weight multiplication unit 5 of the wireless transmission device performs the configuration and operation shown in FIG. 6 is shown, and transmission path estimation processing performed using the first known symbol and the second known symbol is shown. .

  The input first known symbol and second known symbol are separated by the selector 401. If the first known symbol is the first known symbol, the first known symbol (generated by the first known symbol replica generation unit 402) is used. If the complex conjugate of the replica in the frequency domain of the symbol is multiplied and the second known symbol, the complex of the replica in the frequency domain of the second known symbol (generated by the second known symbol replica generation unit 403) is obtained. The conjugate is multiplied.

The multiplication result of the complex conjugate of the first known symbol and its replica in the frequency domain indicates that the transmission path estimation value corresponding to the first transmission antenna and the transmission path estimation value corresponding to the second transmission antenna are the first known This is the result of combining according to the weight multiplied for the symbol. At this time, assuming that the channel estimation value corresponding to the first transmission antenna is H ₁ , the channel estimation value corresponding to the second transmission antenna is H _2, and set 1 is used, the above multiplication Result is,
W ₁₁₁ × H ₁ + W ₁₂₁ × H ₂ (1)
It becomes.

Similarly, the multiplication result of the complex conjugate of the second known symbol and its replica in the frequency domain has the transmission path estimation value corresponding to the first transmission antenna and the transmission path estimation value corresponding to the second transmission antenna as the first. It is the result of combining according to the weights multiplied for two known symbols,
W ₁₁₂ × H ₁ + W ₁₂₂ × H ₂ (2)
It becomes.

Here, when the transmission path estimation process is performed on the set 1,
V ₁₁ = (W ₁₁₁ , W ₁₁₂ ) = (exp (j * 0), exp (j * 0))
V ₁₂ = (W ₁₂₁ , W ₁₂₂ ) = (exp (j * 0), exp (j * π))
Therefore, Formula (1) can be expressed as the following Formula (3), and Formula (2) can be expressed as the following Formula (4).

H ₁ + H ₂ (3)
H ₁ −H ₂ (4)
In FIG. 10, the multiplication result (first multiplication result) of the first known symbol and the complex conjugate of the replica in the frequency domain shown in the above equations (3) and (4), the second known symbol, The multiplication result (second multiplication result) with the complex conjugate of the replica in the frequency domain is added and subtracted.

Formula (3) + Formula (4) = 2H ₁ (5)
Formula (3) -Formula (4) = 2H ₂ (6)
As a result, it is shown that the channel estimation value for each antenna is obtained, and the channel estimation value for each antenna is output to the data symbol demodulator 39.

  Note that the calculations shown in the equations (5) and (6) include an error when there is a large variation in the radio propagation path between the first known symbol and the second known symbol. Therefore, as described above, when the first known symbol and the second known symbol are arranged as close as possible, a highly accurate transmission path estimation value can be obtained even when a large fluctuation on the radio propagation path occurs. Is obtained.

  As shown in FIG. 8, when there are four sets of weights to be multiplied by each known symbol transmitted by each antenna, that is, when the repetition period of the set is 4 slots, as shown in FIG. 11 is added to the transmission path estimation unit 40 of the wireless reception device.

  According to FIG. 11, the transmission path estimated value corresponding to the second transmission antenna obtained as shown in FIG. Further, the selector 404 has a weight indicating to which set the first known symbol and the second known symbol used for the synchronization process detected by the synchronization detection unit 33 belong (for example, among four sets). The set identification information is notified. Based on the identification information, the selector 404 selects a phase rotation amount to be given to a transmission path estimation value corresponding to the second transmission antenna, and the selected phase rotation amount is a transmission path estimation value corresponding to the second transmission antenna. Is given to and then output.

  Depending on which of the four sets the weights multiplied by the first and second known symbols transmitted by the second antenna belong to, the second obtained in the configuration of FIG. The transmission path estimation value (second transmission path estimation value) corresponding to the transmission antenna is different.

For set 1:
W ₁₁₁ × H ₁ + W ₁₂₁ × H ₂ = H ₁ + H ₂
W ₁₁₂ × H ₁ + W ₁₂₂ × H ₂ = H ₁ −H ₂
Therefore, the second transmission path estimation value is 2H ₂ .

For set 2:
_{W 211 × H 1 + W 221} × H 1 = H 1 + j × H 2
W ₂₁₂ × H ₁ + W ₂₂₂ × H ₂ = H ₁ −j × H ₂
Therefore, the second transmission path estimation value is 2j × H ₂ .

For set 3:
W ₃₁₁ × H ₁ + W ₃₂₁ × H ₂ = H ₁ −H ₂
W ₃₁₂ × H ₁ + W ₃₂₂ × H ₂ = H ₁ + H ₂
Therefore, the second transmission path estimation value is −2H ₂ .

For set 4:
W ₄₁₁ × H ₁ + W ₄₂₁ × H ₂ = H ₁ −j × H ₂
W ₄₁₂ × H ₁ + W ₄₂₂ × H ₂ = H ₁ + j × H ₂
Therefore, the second transmission path estimation value is −2j × H ₂ .

  Therefore, when the notified set identification information is the set 1 identification information, the selector 404 selects “no phase rotation”. Then, the second channel estimation value input to the selector 404 is output from the channel estimation unit 40 as it is without giving phase rotation.

  When the notified set identification information is the set 2 identification information, the selector 404 selects phase rotation −j, that is, −90 °. Then, the second transmission path estimation value input to the selector 404 is output from the transmission path estimation unit 40 after being given a phase rotation of −90 °.

  When the notified identification information of the set is the identification information of the set 3, the selector 404 selects phase rotation −1, that is, 180 ° (or −180 °). Then, the second transmission path estimation value input to the selector 404 is output from the transmission path estimation unit 40 after being given a phase rotation of 180 ° (or −180 °).

  When the notified set identification information is the set 4 identification information, the selector 404 selects the phase rotation j, that is, 90 °. Then, the second transmission path estimation value input to the selector 404 is 90. After being given a phase rotation of °, it is output from the transmission path estimation unit 40.

[Other examples of weight multiplier]
FIG. 12 shows an example of a frame format related to still another operation of the first and second weight multipliers 5a and 5b. The frame format shown in FIG. 12 is a modification of the frame format shown in FIG. 2, and specifically, in some of the slots including the first known symbol and the second known symbol. Differs from FIG. 2 in that a notification symbol is further included.

  The broadcast symbol means a symbol including information that the wireless transmission device broadcasts to a plurality or all of the wireless reception devices.

  In view of synchronization processing in a wireless communication system, since a wireless transmission device that has transmitted the known signal may be identified at the same time as timing synchronization, notification symbols are arranged before and after the known signal. There is a case. The transmission path estimation value corresponding to the first transmission antenna and the transmission path estimation value corresponding to the second transmission antenna described with reference to FIGS. 9 to 11 are before and after the first known symbol and the second known symbol. The weight multiplication described with reference to FIGS. 6 to 8 is used only for the first known symbol and the second known symbol arranged before and after the broadcast symbol because it is preferably used when demodulating the located symbol. Even if the operation of the unit is applied, the intended effect of the present invention can be obtained.

  As shown in FIG. 12, FIG. 13 shows the first and second preferred symbols when a specific symbol such as a broadcast symbol is arranged at a different period from the first known symbol and the second known symbol. 2 shows the configuration and operation of the second weight multipliers 5a and 5b.

  Here, according to the configuration of the transmission apparatus of FIG. 4, the transmission apparatus is provided with two transmission antennas, and the number N of known symbols is “2”. Furthermore, the weight to be multiplied changes for each slot, and the repetition period is “4”.

  Further, FIG. 13 illustrates a case where specific symbols such as broadcast symbols are arranged in set 1 and set 3 among the above-described four sets.

  The difference from FIG. 8 is that only some weight vectors, that is, weight vectors in a period (set) in which specific symbols such as broadcast symbols are arranged are orthogonal, and in other sets. That is, a weight vector that is not orthogonal is used.

In the example of FIG. 13, since it is assumed that specific symbols such as broadcast symbols are arranged in the set 1 and the set 3, the weight vector V _lm is L = 1, 2, 3, 4, M = 1, 2 and N = 1, 2, so
V11 = (W111, W112) = (exp (j * 0), exp (j * 0))
V12 = (W121, W122) = (exp (j * 0), exp (j * π))
V21 = (W211, W212) = (exp (j * 0), exp (j * 0))
V22 = (W221, W222) = (exp (j * π / 2), exp (j * π / 2))
V31 = (W311, W312) = (exp (j * 0), exp (j * 0))
V32 = (W321, W322) = (exp (j * π), exp (j * 0))
V41 = (W411, W412) = (exp (j * 0), exp (j * 0))
V42 = (W421, W422) = (exp (j * 3π / 2), exp (j * 3π / 2))
It can be expressed as.

  As described above, according to the above embodiment, in the transmission device, the first multiplication unit 5a multiplies the first known symbol and the second known symbol by the first weight sequence, and the second multiplication unit. 5b multiplies the first known symbol and the second known symbol by a second weight sequence orthogonal to the first weight sequence. The first and second known symbols multiplied by the first weight sequence are transmitted from the first antenna 1a, and the first and second known symbols multiplied by the second weight sequence are the second It is transmitted from the antenna 1b.

  That is, the first weight sequence multiplied by the first and second known symbols transmitted from the first antenna 1a and the first and second known symbols transmitted from the second antenna 1b are multiplied. It is orthogonal to the second weight sequence being performed.

  As a result, the receiving apparatus can obtain a propagation path estimation value for each antenna as described below. That is, in the receiving device, the first known symbol and the second known symbol multiplied by the first weight sequence, and the first weight symbol multiplied by the second weight sequence orthogonal to the first weight sequence. When the signal including the known symbol and the second known symbol is received, the separation unit 37 extracts the first known symbol and the second known symbol from the signal. The propagation path estimation unit 40 multiplies the extracted first known symbol by the complex conjugate of the replica of the first known symbol and the extracted second known symbol to the second known symbol. By adding and subtracting the result obtained by multiplying the complex conjugates of the replicas, the characteristics of the wireless transmission path (propagation value) for each of the two antennas are obtained.

  Thus, according to the above embodiment, the characteristics of the radio transmission path for each antenna can be easily estimated from a plurality of known signals transmitted from a plurality of antennas.

  In the above embodiment, the case where two known signals are transmitted using two antennas has been described as an example. However, the present invention is not limited to this case.

  For example, when the transmission apparatus includes four antennas, four or more known symbols (known symbol group) may be used. In this case, the transmission apparatus stores four orthogonal weight series (weight vectors) including, as elements, a plurality of weights to be multiplied by each known symbol in the storage unit, and the four weight multiplication units use the known symbol group. Are multiplied by one of four weight series, respectively. The four weight multiplication units are assigned with the four weight sequences, and each weight multiplication unit multiplies the known symbol group by the weight sequence assigned to the weight multiplication unit.

  The configuration and operation of the receiving apparatus are the same as those in the above embodiment.

  Thus, according to the above embodiment, the characteristics of the radio propagation path for each antenna can be easily estimated from a plurality of known signals transmitted from a plurality of antennas.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which showed the example of the signal used with the radio | wireless communications system which concerns on this embodiment. The figure which showed an example of the frame format of a radio | wireless transmission signal. The figure which showed the other frame format of the radio transmission signal. The figure which showed the structural example of the radio | wireless transmitter. The figure for demonstrating the weight multiplication process in a prior art. The figure for demonstrating the structure and operation | movement of the weight multiplication part of FIG. The figure for demonstrating the other structure and operation | movement of the weight multiplication part of FIG. The figure for demonstrating the further another structure and operation | movement of the weight multiplication part of FIG. The figure which showed the structural example of the radio | wireless receiver. The figure for demonstrating the structure and operation | movement of the transmission-line estimation part of FIG. FIG. 10 is a diagram for explaining another configuration and operation of the transmission path estimation unit in FIG. 9, and shows a configuration that is further added to the configuration shown in FIG. 10. The figure which showed other frame formats of the radio transmission signal. FIG. 13 is a diagram for explaining the configuration and operation of the weight multiplication unit in FIG. 4 corresponding to the frame format shown in FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (1a, 1b) ... Antenna 2 (2a, 2b) ... Wireless processing part 3 (3a, 3b) ... CP addition part 4 ... Multiplexing part 5 (5a, 5b) ... Weight multiplication part 6 ... Transmission data symbol generation part 7 1st known symbol generation unit 8 2nd known symbol generation unit 500a1 1st weight storage unit 500a2 2nd weight storage unit 500b1 1st weight storage unit 500b2 2nd weight storage unit 501a1 , 501a2, 501b1, 501b2,...

Claims (12)

Generating means for generating a first known symbol and a second known symbol;
A memory for storing a first weight sequence including a weight for multiplying the first known symbol and a weight for multiplying the second known symbol, and a second weight sequence orthogonal to the first weight sequence Means,
First multiplication means for multiplying the first known symbol and the second known symbol by the first weight sequence;
Second multiplying means for multiplying the first known symbol and the second known symbol by the second weight sequence;
A first frame including first and second known symbols multiplied by the first weight sequence, and a second frame including first and second known symbols multiplied by the second weight sequence. Means for generating
First transmission means for transmitting the first frame using a first antenna;
Second transmission means for transmitting the second frame using a second antenna;
A wireless communication device.   The wireless communication apparatus according to claim 1, wherein the first known symbol and the second known symbol are synchronization symbols.   The radio communication apparatus according to claim 1, wherein the first known symbol and the second known symbol in the first and second frames are adjacent to each other. The storage means stores a plurality of first weight sequences and a plurality of second weight sequences orthogonal to each of the plurality of first weight sequences,
The first multiplication means multiplies the first known symbol and the second known symbol by one of the plurality of first weight sequences in a predetermined order,
The second multiplication means multiplies the first known symbol and the second known symbol by one of the plurality of second weight sequences in a predetermined order. The wireless communication apparatus according to claim 1. The storage means includes a first set of a plurality of weight sequences including the first weight sequence, and a second set of a plurality of weight sequences including a second weight sequence orthogonal to the first weight sequence. Remember the set,
The first and second frames include specific time slots having specific information symbols along with the first and second known symbols;
The first multiplying unit multiplies the first known symbol and the second known symbol by each weight sequence in the first set in a predetermined order, and the first weight sequence is , Multiplying the first and second known symbols in the specific time slot in the first frame,
The second multiplication means multiplies the first known symbol and the second known symbol by each weight sequence in the second set in a predetermined order, and the second weight sequence is 2. The wireless communication apparatus according to claim 1, wherein the first and second known symbols in the specific time slot in the second frame are multiplied.   The radio communication apparatus according to claim 5, wherein the specific information symbol is a notification symbol having notification information. Generating means for generating a known symbol group;
Storage means for storing a plurality of orthogonal weight series;
A plurality of multiplication means for multiplying the known symbol group by one of the plurality of weight series;
Transmitting means for transmitting the plurality of known symbol groups each multiplied by the plurality of weight series by the plurality of multiplying means using a plurality of antennas;
Including
The plurality of weight sequences correspond to each of the plurality of antennas;
The plurality of weighting means are respectively assigned to the plurality of multiplying means, and each multiplying means multiplies the known symbol group by the weight series assigned to the multiplying means,
The number of known symbols included in the known symbol group generated by the generating means is equal to or more than the number of antennas. The first known symbol and the second known symbol multiplied by the first weight sequence, and the first known symbol and the second known symbol multiplied by the second weight sequence orthogonal to the first weight sequence. Receiving means for receiving a signal including known symbols of:
Extracting means for extracting the first known symbol and the second known symbol from the signal received by the receiving means;
First multiplying means for multiplying the first known symbol extracted by the extracting means by a complex conjugate of a replica of the first known symbol;
Second multiplying means for multiplying the second known symbol extracted by the extracting means by a complex conjugate of a replica of the second known symbol;
Transmission for estimating the characteristics of the radio transmission path for each of the two antennas by adding and subtracting the multiplication result obtained by the first multiplication means and the multiplication result obtained by the second multiplication means. A route estimation means;
A wireless communication device. A wireless transmission method in a wireless communication device including first and second antennas,
Generating a first known symbol and a second known symbol;
A first multiplication step of multiplying the first known symbol and the second known symbol by a first weight sequence;
A second multiplication step of multiplying the first known symbol and the second known symbol by a second weight sequence orthogonal to the first weight sequence;
A first frame including first and second known symbols multiplied by the first weight sequence; and a second frame including first and second known symbols multiplied by the second weight sequence. Generating and
Transmitting the first frame using the first antenna and transmitting the second frame using the second antenna;
A wireless transmission method including:   The radio transmission method according to claim 9, wherein the first known symbol and the second known symbol are synchronization symbols.   The radio transmission method according to claim 9, wherein the first known symbol and the second known symbol in the first and second frames are adjacent to each other. The first known symbol and the second known symbol multiplied by the first weight sequence, and the first known symbol and the second known symbol multiplied by the second weight sequence orthogonal to the first weight sequence. A receiving step for receiving a signal including known symbols of:
An extraction step of extracting the first known symbol and the second known symbol from the signal received in the reception step;
A first multiplication step of multiplying the first known symbol extracted in the extraction step by a complex conjugate of a replica of the first known symbol;
A second multiplication step of multiplying the second known symbol extracted in the extraction step by a complex conjugate of a replica of the second known symbol;
Transmission for estimating the characteristics of the radio transmission path for each of the two antennas by adding and subtracting the multiplication result obtained in the first multiplication step and the multiplication result obtained in the second multiplication step. A path estimation step;
A wireless reception method including:

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