WO2022162739A1 - 通信路推定方法および無線通信装置 - Google Patents
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0417—Feedback systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
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- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
Definitions
- channel estimation is performed using a virtually generated training signal section.
- SC single carrier
- FIR Finite Impulse Response
- Non-Patent Document 1 discloses a method of estimating a communication channel in an SC-MIMO system using FIR transmission beamforming. Specifically, this document discloses a method of estimating the channel response with the CIR transfer function matrix H(z) when the number of transmitting and receiving antennas is N and the CIR (Channel Impulse Response) length is L. ing.
- the CIR transfer function matrix H(z) is nonsingular, its inverse matrix H(z) ⁇ 1 is the inverse response det ⁇ H(z) ⁇ ⁇ 1 of the determinant det ⁇ H(z) ⁇ and the adjoint matrix adj Obtained by multiplying with ⁇ H(z) ⁇ .
- the inverse matrix H(Z) ⁇ 1 of H(z) is separated into the above adjoint matrix adj ⁇ H(z) ⁇ and the inverse response det ⁇ H(z) ⁇ ⁇ 1 ,
- a technique is disclosed that uses the former as the transmission weight W T (z) and the latter as the reception equalization weight W R (z).
- H(z)W T (z) becomes a diagonal matrix whose diagonal elements are det ⁇ H(z) ⁇ . . Then, when H(z)W T (z) is diagonalized, it is as if N single-input single-output streams are formed between the N transmit antennas and the N receive antennas. An environment similar to that in which the stream is present is established, and interference between streams is suppressed.
- Non-Patent Document 1 furthermore, when the received signal is multiplied by det ⁇ H(z) ⁇ ⁇ 1 as the reception equalization weight W R (z), H(z) is converted into a unit matrix to reduce inter-symbol interference. It is disclosed that it can be suppressed.
- a MIMO system that does not require separation of received signals can be constructed.
- Channel estimation for calculating the reception equalization weight W R (z) is desirably performed using a transmission beam formed by multiplying the transmission weight W T (z). Since the virtual channel after transmission beam formation is represented by the convolution of the channel response between the antennas along with the multiplication of the transmission weight W T (z), it becomes virtually longer than the actual delay wavelength. .
- a delay wavelength that occurs is assumed, and a communication channel is estimated using a training signal section that enables estimation of the delay wavelength.
- the estimable delay wavelength is necessarily fixed.
- the delay wavelength that actually occurs may exceed expectations due to the difference in environment between the transmitting side and the receiving side.
- the virtual communication channel for calculating the reception equalization weight W R (z) may exceed the estimable delay wavelength.
- reception equalization weight W R (z) cannot be calculated correctly, and the bit error rate increases.
- the problem of accuracy deterioration of the reception equalization weight W R (z) can be avoided. deteriorates.
- the present disclosure has been made in view of the above problems, and a first object thereof is to provide a communication path estimation method capable of extending an estimable delay wavelength without extending an actual training signal section.
- a second object of the present disclosure is to provide a wireless communication device that functions as a transmitting station for extending an estimable delay wavelength without extending an actual training signal interval.
- a third object of the present disclosure is to provide a wireless communication device that functions as a receiving station for extending an estimable delay wavelength without extending an actual training signal interval.
- a first aspect relates to a MIMO system comprising a transmitting station having multiple transmitting antennas and a receiving station having multiple receiving antennas, and between the transmitting station and the receiving station A communication channel estimation method for estimating a communication channel, a transmission weight calculating step of calculating an adjoint matrix adjH(z,t) of a transfer function matrix H(z,t) established between the transmitting station and the receiving station as a transmission weight W T (z);
- a training signal that is beamformed by multiplying the transmission signal by the transfer function matrix H(z,t) and the transmission weight W T (z), and containing a known symbol group as a correlation sequence part, is transmitted from the transmission station to the transmitting from at least two of said transmit antennas towards a receiving station; generating a virtual training signal block by serially concatenating the correlation sequence portions included in each of at least two training signals received by at least two of the receiving antennas; By calculating the correlation between the two at each position while sliding the comparison sequence part composed of the same symbol group
- a second aspect is a wireless communication apparatus comprising a plurality of transmitting antennas and forming a MIMO system together with a receiving station having a plurality of receiving antennas, a transmit beamformer including a processor unit and a memory device;
- the transmission beam forming unit a process of acquiring, as a transmission weight W T (z), an adjoint matrix adjH(z,t) of a transfer function matrix H(z,t) established between the wireless communication device and the receiving station;
- a training signal that is beamformed by multiplying the transmission signal by the transfer function matrix H(z,t) and the transmission weight W T (z) and including a known symbol group as a correlation sequence part is directed to the receiving station.
- the receiving station receives a reception equalization weight W R corresponding to the inverse response det ⁇ H(z,t) ⁇ ⁇ 1 of the determinant det ⁇ H(z,t) ⁇ of the transfer function matrix H(z,t) After calculating (z), a process of transmitting a data signal beamformed by multiplying the transmission weight W T (z) to the receiving station; should be performed.
- a third aspect is a wireless communication apparatus comprising a plurality of receiving antennas and configuring a MIMO system together with a transmitting station having a plurality of transmitting antennas, an equalization unit including a processor unit and a memory device;
- the equalization unit At least a training signal that is transmitted from at least two of the transmit antennas in a beamformed state using a transmission weight W T (z) for eliminating inter-stream interference and includes a known symbol group as a correlation sequence part a process of receiving via two said receiving antennas; generating a virtual training signal block by serially concatenating the correlation sequence portions included in each of at least two of the training signals;
- the transmission weight W T (z) is used to calculate the a process of calculating a channel response R(m) virtually realized between the transmitting station and the wireless communication device; a process of calculating a reception equalization weight W R (z) for
- a sufficiently long virtual training signal block can be formed by serially concatenating the correlation sequence parts included in each of at least two training signals. With this virtual training signal block, it is possible to ensure a sufficient sliding range corresponding to a sufficiently long delay. Therefore, according to these aspects, the estimable delay wavelength can be extended without extending the actual training signal section.
- FIG. 1 is a diagram showing a model of a system according to Embodiment 1 of the present disclosure
- FIG. 1 is a block diagram of a system according to Embodiment 1 of the present disclosure
- FIG. 4 is a flowchart for explaining the flow of processing performed by the system according to the first embodiment of the present disclosure
- FIG. 4 is a diagram for explaining a transfer function matrix H(z,t) established between a transmitting station and a receiving station in Embodiment 1 of the present disclosure
- FIG. 4 is a diagram for explaining the relationship between a transmission signal s(t), a transfer function matrix H, and a reception signal Hs(t);
- FIG. 1 is a diagram showing a model of a system according to Embodiment 1 of the present disclosure
- FIG. 1 is a block diagram of a system according to Embodiment 1 of the present disclosure
- FIG. 4 is a flowchart for explaining the flow of processing performed by the system according to the first embodiment of the present disclosure
- FIG. 4 is
- FIG. 4 is a diagram for explaining an example of a method of calculating a channel response R(m) for calculating reception equalization weights
- FIG. 7 is a diagram showing an example of a channel response R(m) obtained by the sliding correlation method shown in FIG. 6
- FIG. 10 is a diagram for explaining a state in which the influence of an unexpected delay cycle is superimposed on the training signal
- FIG. 10 is a diagram for explaining how the calculation accuracy of channel response R(m) deteriorates due to superimposition of an unexpected delay period on the training signal
- FIG. 4 is a diagram for explaining a characteristic method used for calculating channel response R(m) in Embodiment 1 of the present disclosure
- FIG. 1 is a diagram showing a model of a system according to Embodiment 1 of the present disclosure.
- the communication system 10 of this embodiment comprises a transmitting station 12 and a receiving station 16.
- FIG. A transmitting station 12 and a receiving station 16 are spaced apart from each other and each have N antennas.
- the transmitting station 12 and the receiving station 16 constitute a MIMO system, and can perform wireless communication using the N antennas provided by each.
- Multipaths as shown in FIG. 1 are generally formed between each of the antennas of the transmitting station 12 and each of the antennas of the receiving station 16 .
- solid-line arrows indicate paths of direct waves
- dashed-line arrows indicate paths of reflected waves.
- FIG. 2 shows a block diagram of the communication system 10 shown in FIG.
- Transmitting station 12 comprises hardware including a general purpose computer system.
- the hardware includes a processor unit such as a CPU and various memory devices.
- the transmitting station 12 implements the functions of the transmitting station 12 by having the processor unit proceed with processing according to the program stored in the memory device. The same is true for the receiving station 16 as well.
- the transmitting station 12 has a transmission beam forming section 14 as shown in FIG.
- the transmission beam forming unit 14 is provided with N transmission signals s 1,t to s N,t at time t.
- Each of the transmission signals s 1,t to s N,t is a signal corresponding to each of the N antennas ATt(1) to ATt(N).
- the transmission beam forming unit 14 can generate a transmission beam by multiplying the transmission signal s 1,t to s N,t by the transmission weight W T (z).
- the receiving station 16 comprises an equalizer 18 .
- the equalization unit 18 is provided with received signals y 1,t to y N,t that have reached the antennas ATr(1) to ATr(N) at time t.
- the equalization unit 18 multiplies the reception signals y 1,t to y N,t by the reception equalization weight W R (z), thereby performing equalization processing for demodulating the transmission signal.
- FIG. 3 is a flowchart for explaining the details of the processing performed by the transmitting station 12 and the receiving station 16 in this embodiment.
- a training signal is sent from the transmitting station 12 to the receiving station 16 (step 100).
- the training signal transmitted in this step 100 is a signal necessary for calculating the transmission weight W T (z).
- training signals are sequentially transmitted to the receiving station 16 from each of the transmitting antennas ATt(1) to ATt(N).
- the receiving station 16 which has received the training signal at each of the receiving antennas ATr(1) to ATr(N), estimates the channel response based on those signals (step 200).
- FIG. 4 is a diagram for explaining the principle by which the receiving station 16 estimates the channel response based on the training signal sent from the transmitting station 12.
- the upper part of FIG. 4 shows the gain of the received signal obtained at the nr-th receiving antenna ATr(n r ) due to the training signal transmitted from the n t -th transmitting antenna ATt(n t ) at time t. (amplitude).
- the signal transmitted from the transmitting station 12 reaches the receiving station 16 via multipaths.
- the signal that has passed through the path of the reflected wave arrives with a delay and attenuation compared to the signal that has passed through the path of the direct wave.
- an input as shown in the upper part of FIG. 4 is generally obtained.
- FIG. 5 shows how signals s 1,t , s 2,t , s 3,t are transmitted from three transmit antennas in 3 ⁇ 3 MIMO.
- the received signal Hs(t) obtained by the three receiving antennas is obtained using each element of the transfer function matrix H(z,t) representing the estimated channel response, as shown in the lower part of FIG. can be represented.
- the transmission signal is multiplied by an appropriate transmission weight W T (z) together with the transfer function matrix H(z,t).
- W T (z) the transmission weight W T (z)
- H(z,t) the transfer function matrix
- each of the received signals y 1,t to y n,t contains only a single transmitted signal, and that all streams have the same indicates the channel response of
- N streams are formed between the transmitting station 12 and the receiving station 16, each of which exhibits single-input single-output characteristics and which can be represented by the same channel response.
- a process of setting the inverse response det ⁇ H(z,t) ⁇ ⁇ 1 of the determinant det ⁇ H(z,t) ⁇ to the reception equalization weight W R (z) is necessary thereafter. Signal separation processing may be unnecessary.
- the receiving station 16 feeds back the channel information to the transmitting station 12 after step 200 in order to realize the above function (step 202).
- the information of the transfer function matrix H(z,t) estimated in step 200 is fed back.
- the transmitting station 12 Upon receiving the feedback, the transmitting station 12 acquires information on the transfer function matrix H(z,t) as communication channel information (step 102).
- the transmitting station 12 then calculates the adjoint matrix adj ⁇ H(z,t) ⁇ of the transfer function matrix H(z,t) as the transmission weight W T (z) for FIR beamforming (step 104).
- the transmitting station 12 transmits the FIR beam formed using the transmission weight W T (z) as a training signal for calculating the reception equalization weight W R (z) (step 106).
- the inverse response det ⁇ H(z,t) ⁇ ⁇ 1 of the determinant det ⁇ H(z,t) ⁇ of H(z,t) representing the channel response is received and equalized. Used as weight W R (z). Therefore, the reception equalization weight W R (z) can also be calculated from H(z,t) obtained in the process of step 200 .
- the environment between the transmitting station 12 and the receiving station 16 changes over time due to, for example, movement of a mobile object located between them.
- channel estimation is performed again for calculating the reception equalization weight W R (z).
- the FIR beams formed by multiplying the transmission weights W T (z) can be treated as if no interference occurs between streams. Therefore, in this step 106, it is possible to simultaneously transmit up to N training signals from the N transmitting antennas ATt(1) to ATt(N). In this embodiment, it is assumed that at least two training signals are transmitted simultaneously in this step 106 .
- FIG. 6 is a diagram for explaining a basic method of calculating the channel response R(m) for calculating the reception equalization weight W R (z).
- the principle of calculating the channel response R(m) for calculating the reception equalization weight W R (z) by the sliding correlation method will be described.
- the upper part of FIG. 6 shows an example of a training signal sent from one transmitting antenna when using the sliding correlation technique.
- the training signal shown in FIG. 6 includes a prefix part Sprefix, an M-sequence part S, and a suffix part Ssuffix.
- This training signal contains T symbols (eg, 60 symbols).
- the M sequence part S is a correlation sequence of T M symbols (for example, 31 symbols) and has symbols of s 0 to s TM ⁇ 1 (for example, s 0 to s 30 ).
- the prefix part Sprefix includes the latter half of the M-sequence part S, Tpre symbols (for example, 15 symbols, s 16 to S 30 ).
- the suffix part Ssuffix includes the first half Tsuf symbols of the M-sequence part S (for example, 14 symbols, s 0 to S 13 ).
- the symbol name of r m (eg, r 0 ) is attached to the beginning of the M-sequence part S of the training signal, and the symbol name of r m + TM (eg, r 31 ) is attached to the beginning of the suffix part Ssuffix. attached.
- the M-sequence part S for comparison is shown so that the head position of the M-sequence part S of the training signal is aligned.
- the M-sequence part S in the lower part of FIG. 6 also includes T M symbols of s 0 to s TM-1 , like the M-sequence part S of the training signal.
- a downward-sloping triangular figure is written in each of the prefix part Sprefix, the M-sequence part S, and the suffix part Ssuffix. Since the training signal shown in FIG. 6 reaches the receiving station 16 via multipaths, it reaches the receiving station 16 with delay and attenuation like the signal shown in the upper part of FIG.
- a triangular figure written in the prefix part Sprefix indicates the delay and attenuation appearing in the head symbol of the prefix part Sprefix. The same applies to the triangles written in the M-sequence part S and the suffix part Ssuffix. All symbols included in the training signal in the upper part of FIG. 6 reach the receiving station 16 with similar delay and attenuation.
- the gain of each symbol included in the training signal is the largest in the case of zero delay. Therefore, the correlation between the upper M-sequence part S and the lower M-sequence part S is shown in FIG. It is the highest when it is in the positional relationship shown. Sliding the lower M-sequence part S backward by one symbol results in a comparison with the M-sequence part S attenuated by one symbol, so the correlation is lowered accordingly. Similarly thereafter, the correlation between the two decreases as the M-sequence part S in the lower stage slides backward.
- the end of the lower M-sequence part S matches the end of the upper suffix part Ssuffix.
- the correlation between the two is calculated by sliding the lower M-sequence part S up to .
- the correlation at each position in the course of sliding is calculated by the following equation.
- the prefix part Sprefix may be affected by the delay component of the previous slot of the signal. Therefore, in the present embodiment, the prefix part Sprefix is excluded from comparison targets for calculating the correlation, and the channel response R(m) is estimated using the symbols after the beginning of the M sequence part S.
- the prefix part Sprefix in order to create a guard area between the previous slot and the previous slot, it is necessary to include the prefix part Sprefix in the training signal.
- FIG. 7 shows the channel response obtained by plotting the correlation R(m) calculated by the above method in relation to the slide amount. Similar to the channel response Hn r n t (z, t) shown in [Equation 1], the channel response shown in FIG. It correctly represents the multipath situation with the receiving antenna.
- the transfer function matrix (for convenience, H(z,t)) virtually established between the transmitting station 12 and the receiving station 16 is a diagonal matrix with R(m) as the diagonal element. . Then, by obtaining the inverse response det ⁇ H(z,t) ⁇ -1 based on that R(m), it is possible to obtain an appropriate reception equalization weight W R (z).
- the slide described above can be repeated until the end s TM ⁇ 1 of the M sequence part S in the lower part of FIG. 6 matches the end rm +TM+Tsuf of the suffix part Ssuffix in the upper part.
- the upper limit of the slide range is Tsuf+1 as shown in FIG. If the delay period of the training signal falls within the range of Tsuf+1, it is possible to obtain a channel response R(m) that correctly reflects the multipath state. Therefore, in this case, an appropriate receive equalization weight W R (z) can be calculated based on the channel response.
- the training signal for calculating the reception equalization weight W R (z) is multiplied by the transmission weight W T (z).
- the signal reaching the receiving station 16 is obtained by multiplying the transmission signal s i,t by det ⁇ H(z,t) ⁇ , as shown in [Equation 4] above.
- H(z,t) is a 2 ⁇ 2 matrix
- det ⁇ H(z,t) ⁇ H 11 (z,t)H 22 (z,t) ⁇ H 12 (z,t )H 21 (z,t).
- FIG. 8 shows an example of a training signal for calculating the reception equalization weight W T (z) generated as a result of the environment between the transmitting station 12 and the receiving station 16 exhibiting a delay period L exceeding the initial assumption. show.
- this training signal for example, the influence of the delay of the leading symbol of the M-sequence part S extends to near the end of the M-sequence part S.
- FIG. 9 shows how the second half of the channel response R(m) protrudes from the slide range Tsuf+1.
- FIG. 10 is a diagram for explaining a technique used in this embodiment to solve the above problem. More specifically, FIG. 10 shows a configuration example of a training signal for calculating reception equalization weight W R (z) used in this embodiment when the communication system 10 is a 2 ⁇ 2 MIMO system.
- the training signal shown on the left side of the upper row represents the training signal #1 delivered in the first stream formed between the first transmitting antenna ATt(1) and the first receiving antenna ATr(1).
- the training signal #1 includes a prefix part Sprefix including Tpre_symbols (for example, 29 symbols) and an M -sequence part S including TM symbols.
- this training signal does not include the suffix part Ssuffix that the training signal shown in FIG. 6 has.
- the M sequence part S contains TM symbols (for example, 31 symbols) as in the case of the training signal shown in FIG. Specifically, the symbols s 0 to s TM ⁇ 1 (for example, s 0 to s 30 ) are included.
- the prefix part Sprefix includes Tpre ⁇ symbols (for example, 29 symbols).
- Tpre ⁇ is equal to the number of symbols Tpre+Tsuf included in the prefix part Sprefix and the suffix part Ssuffix of the training signal shown in FIG. Therefore, the total number of symbols #1 in the training signal shown in FIG. 10 is the same number (for example, 60) as the total number of symbols in the training signal shown in FIG.
- the prefix part Sprefix contains Tpre ⁇ symbols belonging to the latter half of s 0 to s TM ⁇ 1 (for example, s 0 to s 30 ) constituting the M-sequence part S, that is, It is assumed that s TM-1-Tpre und to s TM-1 (for example, s 2 to s 30 ) are included.
- the training signal shown on the right side of the upper row is the training signal #2 delivered in the second stream formed between the second transmitting antenna ATt(2) and the second receiving antenna ATr(2).
- a signal similar to training signal #1 is exchanged between transmitting station 12 and receiving station 16 as training signal #2.
- the receiving station 16 receives training signal #1 and training signal #2 as exactly the same signal.
- the two training signals #1 and #2 are sent from the transmitting station 12 at the same time. Therefore, the signals are received at the receiving station 16 simultaneously.
- FIG. 10 shows a signal obtained by serially synthesizing the M-sequence parts S of two training signals #1 and #2. This signal is hereinafter referred to as the "virtual training signal block".
- the virtual training signal block This signal is hereinafter referred to as the "virtual training signal block".
- triangular figures superimposed on the prefix part Sprefix and the M-sequence part S indicate the state of delay and attenuation appearing in the head symbol of each part, as in the case shown in FIG.
- the prefix part Sprefix is easily affected by the delay component of the previous slot.
- the receiving station 16 of the present embodiment calculates the channel response R(m) with the virtual training signal block shown in the lower part of FIG. 10 as the object of slide correlation.
- the calculation of the sliding correlation starts from the state where the head of the M-sequence part S for comparison (corresponding to the M-sequence part S shown in the lower part of FIG. 6) matches the head of the virtual training signal block, and It can be repeated until the end of the sequence part S matches the end of the virtual training signal block.
- the slide range is expanded from Tsuf+1 (eg, 15) to T M +1 (eg, 32) compared to the example shown in FIG. be able to. If the slide range is expanded in this way, even if the delay order N(L-1)+1 of the training signals #1 and #2 becomes a large value, the channel response R(m) can be properly calculated. can be done.
- a virtual training signal block is generated by concatenating the M-sequence parts S that are simultaneously transmitted in multiple streams. Therefore, the training signal is not extended as compared with the case shown in FIG. 6, and the time required for sending and receiving the training signal is not extended. Therefore, according to the method of the present embodiment, it is possible to extend the estimable delay wavelength without any deterioration in transmission capacity.
- step 106 multiple training signals are sent from the transmitting station 12 to the receiving station 16 via multiple streams exhibiting the same channel response, as described above.
- the receiving station 16 extracts the M-sequence part S from the signals received by each stream #1 to #N (step 204).
- Receiving station 16 then serially concatenates the M-sequence portions to generate a virtual training signal block (step 206).
- a virtual training signal block In the example described with reference to FIG. 10, two M-sequence parts S are concatenated, but the number is not limited to two. If a larger sliding range is required, three or more M-sequence parts S obtained from three or more streams may be concatenated in this step 206 .
- the channel response R(m) is calculated by the sliding correlation technique (step 208).
- reception equalization weight W R (z) is calculated based on the channel response R(m) (see FIG. 7) calculated in the above process (step 210).
- the training processing in the transmitting station 12 and the receiving station 16 is completed.
- the transmitting station 12 transmits the data signal formed with the FIR beam by the transmission weight W T (z) (step 108).
- the receiving station 16 also demodulates the transmission data by equalizing the received signal with the reception equalization weight W R (z) (step 212). This establishes communication by the N ⁇ N MIMO system.
- the M sequence is used as the training signal for calculating the reception equalization weight W R (z), but the present disclosure is not limited to this.
- the M-sequence another sequence that is generally used for channel response estimation may be used.
- the first embodiment described above does not include processing for notifying the transmitting station 12 that the receiving station 16 has finished calculating the reception equalization weight W R (z). However, the receiving station 16 notifies the transmitting station 12 of the end of calculation of W R (z), and the transmitting station 12 waits for the notification before starting the processing of step 108, that is, the transmission of the data signal. good.
- Tpre ⁇ is equal to or close to TM.
- the value of Tpre ⁇ is preferably greater than 1/2 of TM (eg, 15.5).
- the value of Tpre ⁇ is preferably greater than 2/3 of TM (eg, 20.7), more preferably greater than 3/4 of TM (eg, 23.25). preferable.
- the transmitting station 12 and the receiving station 16 are base stations for wireless communication, but the present disclosure is not limited to this.
- the transmitting station 12 and receiving station 16 in this disclosure may be implemented in user terminals.
- the transmitting station 12 calculates the transmission weight W T (z), but the present disclosure is not limited to this.
- the transmission weight W T (z) may be calculated by the receiving station 16 and may be fed back to the transmitting station 12 by the receiving station 16 .
- the M sequence part S shown in FIG. It corresponds to the "comparative series section" described.
- the transmitting station 12 corresponds to the “wireless communication apparatus” according to claims 5 and 6
- the receiving station 16 corresponds to the "wireless communication apparatus” according to claims 7 and 8. ” is equivalent to
Abstract
Description
前記送信局と前記受信局との間に成立する伝達関数行列H(z,t)の随伴行列adjH(z,t)を、送信ウェイトWT(z)として算出する送信ウェイト算出ステップと、
送信信号に前記伝達関数行列H(z,t)と共に前記送信ウェイトWT(z)を乗算することでビーム形成され、既知のシンボル群を相関系列部として含むトレーニング信号を、前記送信局から前記受信局に向けて、少なくとも二つの前記送信アンテナから送出するステップと、
少なくとも二つの前記受信アンテナで受信した少なくとも二つのトレーニング信号の夫々に含まれる前記相関系列部を直列に連結することで仮想トレーニング信号ブロックを生成するステップと、
前記相関系列部と同じシンボル群からなる比較系列部を前記仮想トレーニング信号ブロックに対してスライドさせながら各位置における両者の相関を計算することで、前記送信ウェイトWT(z)を用いることにより前記送信局と前記受信局との間に仮想的に実現されている通信路応答R(m)を計算するステップと、
前記通信路応答R(m)に基づいて、前記伝達関数行列H(z,t)の行列式det{H(z,t)}の逆応答det{H(z,t)}-1に相当する受信等化ウェイトWR(z)を算出するステップと、
を含むことが望ましい。
プロセッサユニットとメモリ装置とを含む送信ビーム形成部を備え、
前記送信ビーム形成部は、
当該無線通信装置と前記受信局との間に成立する伝達関数行列H(z,t)の随伴行列adjH(z,t)を、送信ウェイトWT(z)として取得する処理と、
送信信号に前記伝達関数行列H(z,t)と共に前記送信ウェイトWT(z)を乗算することでビーム形成され、既知のシンボル群を相関系列部として含むトレーニング信号を、前記受信局に向けて、少なくとも二つの送信アンテナから送出する処理と、
前記受信局が、前記伝達関数行列H(z,t)の行列式det{H(z,t)}の逆応答det{H(z,t)}-1に相当する受信等化ウェイトWR(z)を算出した後に、前記受信局に向けて、前記送信ウェイトWT(z)を乗算することでビーム形成したデータ信号を送出する処理と、
を実行することが望ましい。
プロセッサユニットとメモリ装置とを含む等化部を備え、
前記等化部は、
ストリーム間の干渉を排除するための送信ウェイトWT(z)を用いてビーム形成された状態で少なくとも二つの前記送信アンテナから送出され、既知のシンボル群を相関系列部として含むトレーニング信号を、少なくとも二つの前記受信アンテナを介して受信する処理と、
少なくとも二つの前記トレーニング信号の夫々に含まれる前記相関系列部を直列に連結することで仮想トレーニング信号ブロックを生成する処理と、
前記相関系列部と同じシンボル群からなる比較系列部を前記仮想トレーニング信号ブロックに対してスライドさせながら各位置における両者の相関を計算することで、前記送信ウェイトWT(z)を用いることにより前記送信局と当該無線通信装置との間に仮想的に実現されている通信路応答R(m)を計算する処理と、
前記通信路応答R(m)に基づいて、受信信号から送信信号を復調するための受信等化ウェイトWR(z)を算出する処理と、
を実行することが望ましい。
[実施の形態1の構成]
図1は、本開示の実施の形態1のシステムのモデルを示す図である。図1に示すように、本実施形態の通信システム10は、送信局12および受信局16を備えている。送信局12と受信局16は、互いに離間して配置されており、夫々がN個のアンテナを備えている。
図3は、本実施形態において送信局12と受信局16で実施される処理の内容を説明するためのフローチャートである。
図3に示すように、本実施形態では、先ず、送信局12から受信局16に向けて、トレーニング信号が送出される(ステップ100)。本ステップ100で送信されるトレーニング信号は、送信ウェイトWT(z)を計算するために必要な信号である。
図4の上段は、nt番目の送信アンテナATt(nt)から時刻tに送出されたトレーニング信号に起因して、nr番目の受信アンテナATr(nr)で得られた受信信号の利得(振幅)を示している。図中、例えば|h(0)nrnt(t)|に含まれる(0)、|h(L-1)nrnt(t)|に含まれる(L-1)は、夫々遅延の次数を表している。図1を参照して説明した通り、送信局12から送信される信号は、マルチパスを介して受信局16に到達する。この際、直接波のパスを経由した信号に比して、反射波のパスを経由した信号は、遅延して、かつ減衰して到達する。その結果、受信アンテナATr(nr)では、一般に図4上段に示すような入力が得られる。
図6は、受信等化ウェイトWR(z)算出のための通信路応答R(m)を計算する基本の手法を説明するための図である。ここでは、受信等化ウェイトWR(z)算出のための通信路応答R(m)を、スライド相関の手法で計算する原理を説明する。
det{H(z,t)}=X0+X1z-1+ … +XN(L-1)+1z-N(L-1)-1
ステップ106では、上記の通り、同じ通信路応答を示す複数のストリームを介して、複数のトレーニング信号が送信局12から受信局16に送出される。受信局16は、夫々のストリーム#1~#Nで受信した信号から、M系列部Sを抽出する(ステップ204)。
ところで、上述した実施の形態1では、受信等化ウェイトWR(z)を算出するためのトレーニング信号にM系列を用いることとしているが、本開示はこれに限定されるものではない。M系列に代えて、通信路応答の推定に一般に用いられる他の系列を用いることとしてもよい。
12 送信局
16 受信局
ATt(1)~ATt(N) 送信アンテナ
ATr(1)~ATr(N) 受信アンテナ
Hnrnt(z,t) 送信アンテナATt(nt)と受信アンテナATr(nr)との間の通信路応答
H(z,t) 送信局と受信局の間の伝達関数行列
adj{H(z,t)} H(z,t)の随伴行列
det{H(z,t)} H(z,t)の行列式
det{H(z,t)}-1 det{H(z,t)}の逆応答
WT(z) 送信ウェイト
WR(z) 受信等化ウェイト
R(m) スライド相関の手法で演算された通信路応答
Claims (8)
- 複数の送信アンテナを有する送信局と、複数の受信アンテナを有する受信局とを備えるMIMOシステムに関して、前記送信局と前記受信局との間の通信路を推定する通信路推定方法であって、
前記送信局と前記受信局との間に成立する伝達関数行列H(z,t)の随伴行列adjH(z,t)を、送信ウェイトWT(z)として算出する送信ウェイト算出ステップと、
送信信号に前記伝達関数行列H(z,t)と共に前記送信ウェイトWT(z)を乗算することでビーム形成され、既知のシンボル群を相関系列部として含むトレーニング信号を、前記送信局から前記受信局に向けて、少なくとも二つの前記送信アンテナから送出するステップと、
少なくとも二つの前記受信アンテナで受信した少なくとも二つのトレーニング信号の夫々に含まれる前記相関系列部を直列に連結することで仮想トレーニング信号ブロックを生成するステップと、
前記相関系列部と同じシンボル群からなる比較系列部を前記仮想トレーニング信号ブロックに対してスライドさせながら各位置における両者の相関を計算することで、前記送信ウェイトWT(z)を用いることにより前記送信局と前記受信局との間に仮想的に実現されている通信路応答R(m)を計算するステップと、
前記通信路応答R(m)に基づいて、前記伝達関数行列H(z,t)の行列式det{H(z,t)}の逆応答det{H(z,t)}-1に相当する受信等化ウェイトWR(z)を算出するステップと、
を含む通信路推定方法。 - 前記トレーニング信号は、プレフィックス部Sprefixと、当該プレフィックス部Sprefixに続く前記相関系列部とを備え、
前記プレフィックス部Sprefixのシンボル数Tpreは、前記相関系列部のシンボル数TMの1/2以上である請求項1に記載の通信路推定方法。 - 前記送信ウェイト算出ステップは、
前記送信局が、前記複数の送信アンテナの夫々から、順次、送信ウェイト算出用トレーニング信号を送出するステップと、
前記受信局が、前記複数の受信アンテナの夫々で受信した前記送信ウェイト算出用トレーニング信号に基づいて、前記複数の送信アンテナの夫々と前記複数の受信アンテナの夫々との間に成立する通信路応答Hnrnt(z,t)を推定するステップと、
それらの通信路応答Hnrnt(z,t)に基づいて前記伝達関数行列H(z,t)を設定するステップと、
を含む請求項1または2に記載の通信路推定方法。 - 前記受信等化ウェイトWR(z)の算出後に、前記送信局が、前記受信局に向けて、前記送信ウェイトWT(z)を乗算することでビーム形成したデータ信号を送出するステップと、
前記受信局が、ビーム形成された前記データ信号を、前記受信等化ウェイトWR(z)で処理することにより送信データに復調するステップと、
を含む請求項1乃至3の何れか1項に記載の通信路推定方法。 - 複数の送信アンテナを備え、複数の受信アンテナを有する受信局と共にMIMOシステムを構成する無線通信装置であって、
プロセッサユニットとメモリ装置とを含む送信ビーム形成部を備え、
前記送信ビーム形成部は、
当該無線通信装置と前記受信局との間に成立する伝達関数行列H(z,t)の随伴行列adjH(z,t)を、送信ウェイトWT(z)として取得する処理と、
送信信号に前記伝達関数行列H(z,t)と共に前記送信ウェイトWT(z)を乗算することでビーム形成され、既知のシンボル群を相関系列部として含むトレーニング信号を、前記受信局に向けて、少なくとも二つの送信アンテナから送出する処理と、
前記受信局が、前記伝達関数行列H(z,t)の行列式det{H(z,t)}の逆応答det{H(z,t)}-1に相当する受信等化ウェイトWR(z)を算出した後に、前記受信局に向けて、前記送信ウェイトWT(z)を乗算することでビーム形成したデータ信号を送出する処理と、
を実行する無線通信装置。 - 前記トレーニング信号は、プレフィックス部Sprefixと、当該プレフィックス部Sprefixに続く前記相関系列部とを備え、
前記プレフィックス部Sprefixのシンボル数Tpreは、前記相関系列部のシンボル数TMの1/2以上である請求項5に記載の無線通信装置。 - 複数の受信アンテナを備え、複数の送信アンテナを有する送信局と共にMIMOシステムを構成する無線通信装置であって、
プロセッサユニットとメモリ装置とを含む等化部を備え、
前記等化部は、
ストリーム間の干渉を排除するための送信ウェイトWT(z)を用いてビーム形成された状態で少なくとも二つの前記送信アンテナから送出され、既知のシンボル群を相関系列部として含むトレーニング信号を、少なくとも二つの前記受信アンテナを介して受信する処理と、
少なくとも二つの前記トレーニング信号の夫々に含まれる前記相関系列部を直列に連結することで仮想トレーニング信号ブロックを生成する処理と、
前記相関系列部と同じシンボル群からなる比較系列部を前記仮想トレーニング信号ブロックに対してスライドさせながら各位置における両者の相関を計算することで、前記送信ウェイトWT(z)を用いることにより前記送信局と当該無線通信装置との間に仮想的に実現されている通信路応答R(m)を計算する処理と、
前記通信路応答R(m)に基づいて、受信信号から送信信号を復調するための受信等化ウェイトWR(z)を算出する処理と、
を実行する無線通信装置。 - 前記等化部は、
前記受信等化ウェイトWR(z)の算出後に、前記送信局が、前記受信局に向けて、前記送信ウェイトWT(z)を乗算することでビーム形成したデータ信号を受信する処理と、
ビーム形成された前記データ信号を、前記受信等化ウェイトWR(z)で処理することにより送信データに復調する処理と、
を更に実行する請求項7に記載の無線通信装置。
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