JP2009010968A - Wireless transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further stabilize communication by transmitting a transmission stop signal to a partner with whom communication may not be performed any more. <P>SOLUTION: The present invention relates to a wireless transmission apparatus comprising a plurality of terminals A-D for performing transmission/reception, each of the terminals A-D being configured to transmit at least one or more transmission stop signals for commanding transmission stop, by utilization directions, to another terminal that is not a target of transmission/reception. For example, on the assumption that the terminal A transmits a predetermined signal to search for the terminal B, upon receipt of the signal, the terminal B recognizes the signal as a communication request to the terminal itself, performs a propagation path estimation and a transmission scheme determination and redirects a control signal to the terminal A. On the other hand, the terminal C, D receives the signal from the terminal A, recognizes that the signal is not a transmission request to the terminal itself, enters a standby state, then receives the control signal from the terminal B to the terminal A as a transmission stop signal, and stops communication operation so as not to communicate any more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio transmission apparatus, and more particularly to a radio transmission apparatus that performs signal transmission using a plurality of antennas at a transmission / reception station.

  As a signal transmission method for performing high-speed signal transmission in wireless communication, research on a MIMO (Multi-Input Multi-Output) system using a plurality of antennas at a transmitting / receiving station has been actively conducted in recent years. In a MIMO system, it is known that a high capacity can be achieved by using a plurality of antennas at a transmission / reception station as compared with a case where only one antenna is used at a transmission / reception station (see, for example, Patent Documents 1 and 2). ).

  In the MIMO system, there are a method using space time coding (Space-Time Coding) and a method using beam forming. In the method using space time coding, as shown in FIG. 15, the transmission side encodes a signal and transmits an uncorrelated signal from each antenna. In this configuration, since the transmission station does not perform weighting multiplication on the signal, the configuration is greatly different from that of the present invention described later that performs weighting multiplication.

Therefore, a case where beam forming is used as a conventional technique instead of a method using space time coding will be described. As a conventional example using beam forming, for example, Karasawa, “Spatial Time Communication Modeling”, 2001 SITA Workshop, Nov. 2001. There is what is described in. FIG. 16 shows a configuration of a transmission / reception station when performing transmission / reception beam forming. In FIG. 16, 101 is a transmission weight multiplication device (transmission station), 102 is a propagation path, and 103 is a reception weight multiplication device (reception station). In this method, transmission beam forming is performed at the transmitting station and reception beam forming is performed at the receiving station. The signal processing configuration of this method will be described below. Here, the description will proceed with N transmission antennas and M reception antennas. Further, the propagation coefficient from the transmission antenna n to the reception antenna m is represented as h _mn, and the propagation characteristic between the transmitting and receiving stations is represented as a matrix H = [h _mn ].

As shown in FIG. 16, the transmitting station multiplies the time series data S (t) to be transmitted by a transmission weight W _1n for each antenna and transmits a signal. The transmission signal passes through the propagation path H (reference numeral 102) and is received by M reception antennas. The receiving station multiplies the signals received at the M antennas by the weight v _1m at the antenna m, and then performs signal synthesis.

In the following, this series of processes is expressed using mathematical formulas. If the received signal at the receiving antenna m is x _m (p), the received vector x (p) = [x ₁ (p),..., X _M (p)] ^T is given by the following equation.
x (p) = Hws (p) + z (p)
Here, w = [w ₁ ,..., W _N ] ^T is a transmission weight vector, z _m (p) is an interference noise component at antenna m, and z (p) = [z ₁ (p),. •, z _M (p)] ^T represents an interference noise vector. The final output y after weight multiplication and signal synthesis on the receiving side is given by the following equation.
y (p) = v ^T x (p)
= V ^T Hws (p) + v ^T z (p)
Although various determination methods can be considered for the transmission weight w and the reception weight v, the transmission / reception weight is determined so that the reception signal level is as high as possible.

  This series of signal processing can also be described using the transmission / reception beam pattern shown in FIG. On the transmission side, the transmission signal power varies depending on the direction by weighted transmission from a plurality of antennas, and a transmission beam is formed. Similarly, a reception beam is formed on the reception side. In this way, the transmission / reception stations perform beam forming, respectively, so that signals can be received with high signal power. Note that the signal processing configuration in FIG. 16 and the beam pattern in FIG. 17 only show the same phenomenon with different explanations. In particular, the beam pattern has the advantage of being intuitively easy to understand. On the contrary, the signal processing configuration is suitable for describing a strict description, and the following description will be given with an emphasis on details of signal processing.

JP-T-2001-505723 JP 2001-237751 A

  In the conventional beam forming method, when one signal is transmitted and received in one-to-one communication, a plurality of signals cannot be simultaneously transmitted in parallel. For this reason, there has been a limit on the transmission rate of signals that can be transmitted. For this reason, there has been a problem that the user's request to perform higher-speed wireless communication cannot be sufficiently satisfied.

  The present invention has been made to solve such a problem, and obtains a wireless transmission device capable of further stabilizing communication by transmitting a transmission stop signal to a partner that does not perform communication. It is an object.

  The present invention is a wireless transmission device including a plurality of terminal devices for performing transmission / reception, wherein the terminal device instructs other terminal devices not to be transmitted / received to stop transmission for each usage direction. At least one transmission stop signal for transmitting.

  The present invention is a wireless transmission device including a plurality of terminal devices for performing transmission / reception, wherein the terminal device instructs other terminal devices not to be transmitted / received to stop transmission for each usage direction. Since at least one transmission stop signal is transmitted for transmission, a transmission stop signal can be transmitted to a non-communication partner even if a plurality of terminal devices exist in the vicinity. Can be further stabilized.

Embodiment 1 FIG.
The present embodiment relates to a transmission method using a plurality of transmission / reception beams. FIG. 1 is a configuration diagram showing the configuration of the present embodiment. In FIG. 1, 1 is a transmission signal, 2 is a transmission antenna (array antenna), 3 is a reception antenna (array antenna), 4 is a reception signal, 5 is a transmission station (transmission weight multiplier), 6 is a propagation path, 7 Is a receiving station (receiving weight multiplier). The transmission weight multiplying unit 5, as shown in FIG., The transmitted signal s _{k (t)} and a signal copying means for the N copying, the N transmission signals s _{k (t)} in different weights w and a multiplier for multiplying _kn (k = 1,..., K, n = 1,..., N). The outline of the present invention will be described below with reference to FIG.

In the present embodiment, in one-to-one communication, the transmitting and receiving stations respectively transmit a plurality of signals in parallel using a plurality of beams. In FIG. 1, the transmitting station first prepares _K signals 1s ₁ (t), ..., s _k (t), ..., s _K (t), and copies each of them N times. Te, the weight _w k ₌ for N signals _{s k (t) [w k1} , ···, w kN] T (k = 1, ···, K) after multiplying each one by K pieces The signals are combined and signals are transmitted from the N antennas 2. With this configuration, K beams are formed at the transmitting station.

After passing through the propagation path 6, the receiving side receives signals using M antennas 3. Accordingly, the reception vector is K reception vectors composed of M components. That is, the reception vector x (p) = [x ₁ (p),..., X _M (p)] ^T is given by the following equation.
x (p) = Σ _{k = 1} ^K H w _k s _k (p) + z (p)
Here, z (p) = [z ₁ ,..., Z _M ] ^T represents an interference noise vector. In the above equation, the reception vector of the signal k is given by Hw _k , which differs for each signal. That is, each signal is received at a different reception vector at the receiving station, and depending on the receiving method, the signals can be received separately.

On the receiving side, the weight v _km is multiplied by the antenna m, and signal synthesis for the signal k is performed. The same applies to other signals, and K beams are formed on the receiving side. As described above, in the transmission / reception station according to the present embodiment, a signal is received by forming a plurality of beams at the transmission station and the reception station. FIG. 2 shows an example of transmission / reception beam formation when this embodiment is used. In FIG. 2, 1 is a transmission signal, 2 is a transmission antenna, 3 is a reception antenna, 4 is a reception signal, 5 is a transmission station (transmission weight multiplier), 6 is a propagation path, and 7 is a reception station (reception weight multiplication). Device). In the configuration of FIG. 2, the final output 4y _k (p) after weight multiplication and signal synthesis for the signal k is given by the following equation.
y _k (p) = v _k ^T x (p)
= Σ _{k ′ = 1} ^K v _k ^T Hw _{k ′} s _{k ′} (p) + v _k ^T z (p)
Although various determination methods can be considered for the transmission weight w _k and the reception weight v _k , the transmission / reception weight is determined so that the reception level of the signal k is as high as possible.

  As described above, in this embodiment, a plurality of signals can be simultaneously transmitted in parallel by forming a plurality of beams at the transmitting and receiving stations, so that the user's request to perform more restrictive wireless communication is met. The effect that it can respond to it is acquired.

Embodiment 2. FIG.
In the present embodiment, a case will be described in which a specific reception weight is used in the transmission method using a plurality of transmission / reception beams of the first embodiment.

In the first embodiment, the reception vector x (p) = [x ₁ (p),..., X _M (p)] ^T when transmitting using a plurality of transmission weights is given by the following equation.
x (p) = Σ _{k = 1} ^K H w _k s _k (p) + z (p)
Here, the reception vector of the signal k is given by Hw _k , which differs for each signal. That is, each signal is received at a different reception vector at the receiving station, and a plurality of signals can be received separately from each other depending on the reception method.

Therefore, in the present embodiment, the received vector is determined according to the MMSE combining standard. In the MMSE synthesis machine, there are an SMI algorithm, an RLS algorithm, an LMS algorithm, and the like, but any algorithm may be used here. For example, when the reception weight of the signal k is determined using the SMI algorithm, the reception weight v _k is given by the following equation. Here, Φ is a correlation matrix, and Φ ⁻¹ is its inverse matrix.
v _k = Φ ⁻¹ u _k
Φ = Σ _{p = 1} ^{p = po} x (p) x (p) ^H
u _k = Σ _{p = 1} ^{p = po} x (p) s _k (p) ^*
Here, p0 represents the number of weight calculation samples. This calculation algorithm itself is the same as the conventional method, and the same calculation can be performed for the RLS algorithm and the LMS algorithm. FIG. 3 shows the configuration of the receiving station when the SMI algorithm is used. In FIG. 3, 1 is a transmission signal, 2 is a transmission antenna, 3 is a reception antenna, 4 is a reception signal, 5 is a transmission station (transmission weight multiplication device), 6 is a propagation path, and 7 is a reception station (reception weight multiplication). Device). In the present embodiment, the receiving station 7 includes an MMSE standard algorithm such as an SMI algorithm for determining a reception weight, as shown in the figure.

  The present embodiment is characterized in that an MMSE standard algorithm such as an SMI algorithm is used in determining a plurality of reception weights when performing transmission / reception in one-to-one communication using a plurality of beams (not one). Have. In the example of FIG. 3, the case where the SMI algorithm is used is shown. However, the present invention is not limited to this case. It is done.

In addition to the MMSE standard type algorithm, a method using a maximum ratio combining type weight calculation method is also possible. In this case, the reception weight is determined according to the following equation.
v _k = u _k
u _k = Σ _{p = 1} ^{p = po} x (p) s _k (p) ^*

  In addition to the MMSE reference type algorithm and the maximum ratio combining type, there are many conventional weight calculation algorithms, which can be applied to one-to-one communication using a plurality of beams of the present invention. That is, in this embodiment, each signal is received more efficiently by receiving a signal using a specific weight calculation algorithm in determining the reception weight.

  As described above, according to the present embodiment, the reception weight is determined using the MMSE combining standard or the maximum ratio combining method. Therefore, by using the receiving beam weight calculation method suitable for signal reception, Quality signal reception is possible.

Embodiment 3 FIG.
In the second embodiment described above, when the SMI algorithm is used for the calculation of the reception weight, the correlation matrix can be shared by each reception beam. This signal processing method is shown in FIG. In FIG. 4, 1 is a transmission signal, 2 is a transmission antenna, 3 is a reception antenna, 4 is a reception signal, 5 is a transmission station (transmission weight multiplier), 6 is a propagation path, and 7 is a reception station (reception weight multiplication). Device) 10 receives the received signal x _m (p) received by the receiving antenna 3, and from the received vector x (p), the correlation matrix Φ = Σ _{p = 1} ^{p = po} x (p) x (p The correlation matrix calculation unit calculates ^H and its inverse matrix Φ ⁻¹ . The correlation matrix Φ obtained by the correlation matrix calculation unit 10 and its inverse matrix Φ ⁻¹ are commonly used in the SMI algorithm when calculating each reception weight.

  As described above, in the present embodiment, the basic configuration is the same as that of the second embodiment, but here, by providing the correlation matrix calculation unit 10, the correlation matrix calculation used for each beam and its inverse matrix are provided. The calculation is standardized. With such a configuration, it is possible to reduce the amount of calculation when calculating the reception weight.

Embodiment 4 FIG.
In this embodiment, a method for improving the efficiency of signal transmission using a specific transmission weight in the transmission method using a plurality of transmission / reception beams of Embodiment 1 will be described. FIG. 5 shows the configuration of the transmission / reception station in the present embodiment. In FIG. 5, 1 is a transmission signal, 2 is a transmission antenna, 3 is a reception antenna, 4 is a reception signal, 5 is a transmission station (transmission weight multiplier), 6 is a propagation path, and 7 is a reception station (reception weight multiplication). Device). As described above, the reception vector x (p) = [x ₁ (p),..., X _M (p)] ^T when transmitting using a plurality of transmission weights is given by the following equation.
x (p) = Σ _{k = 1} ^K H w _k s _k (p) + z (p)
Here, the reception vector of the signal k is given by Hw _k , which differs for each signal. At this time, as the vector Hw _k varies greatly depending on the signal, it becomes easier to form a unique beam for each signal on the receiving side and perform signal separation.

Therefore, in the present embodiment, transmission beam forming is performed so that the transmission weights w _k are orthogonal to each other. The orthogonal relationship is given by
w _k1 ^H w _k2 = 0 k1, k2 = 1,..., K (1)
When there are N transmitting antennas, N such orthogonal beams can be generated at the maximum, and the maximum value of K when this method is used is N. In this way, when transmission is performed using orthogonal transmission weights, the reception vectors Hw _k of each signal are likely to be different from each other. When the mutual vectors Hw _k are greatly different, each signal can be easily received and received, and parallel signal transmission can be performed with high quality.

Various methods are conceivable as means for determining the orthogonal transmission weight satisfying the expression (1). For example, if N is a power of 2, such as 2, 4, 8, 16, 32, ...
w _k = [w _k1 ,..., w _kN ] ^T
By expressing each element using a Walsh code or the like, it is possible to create a state in which the correlation between the weight vectors is zero. In the case of 4 antennas, w ₁ = [1, 1, 1, 1] ^T
w ₂ = [1, 1, −1, −1] ^T
w ₃ = [1, −1, 1, −1] ^T
w ₄ = [1, −1, −1, 1] ^T
It becomes. In addition to this, a method of determining a weight vector using the Gramschmitt orthogonalization method for general N is also possible. Also, the transmission quality of this method can be improved by using orthogonal vectors by other methods.

  As described above, according to the present embodiment, transmission is performed using transmission weights that are orthogonal to each other at the transmitting station, so that the channels are close to orthogonal without using propagation information or the like. Is possible.

Embodiment 5 FIG.
In this embodiment, a block configuration in a transmission method using a plurality of transmission / reception beams is described. FIG. 18 is a block configuration diagram showing the present embodiment. In FIG. 18, (a) shows the configuration of the data transmission requesting station, and (b) shows the configuration of the data receiving station.

  In FIG. 18A, S51 is a transmission signal, 52 is a communication request signal generator for generating a communication request signal S52 for requesting the other party to perform communication, and 51 switches between the transmission signal and the communication request signal. A switch 53 is a weight control unit that multiplies the transmission signal S53 output from the switch 51 by a weight for each beam based on the weighting signal S56, and 55 is information S54 weighted and synthesized for each beam and each antenna. And an antenna for receiving the communication request response signal from the receiving station for the communication request signal, S55 for each antenna output of the communication request response signal from the receiving station, and 54 for analyzing the antenna output S55 for each channel used. Is a weight analysis unit for generating the weighting signal S56. In FIG. 18B, 56 is a receiving station side array antenna, S56 is an output of each antenna of a communication request signal from a transmission requesting station, and 57 is a transmission path response S57 between the transmitting and receiving antennas based on information of the antenna output S56. Is a communication channel search unit that analyzes the transmission line response S57 and outputs the state S58 of each communication channel, and 59 is a use channel that selects a use channel based on the state S58 of the communication channel. The selection unit 60 is a power distribution calculation unit that determines the power allocation of each channel based on the information S59 on the channel used, 61 is the channel information S60 including the power allocation of each channel, and determines the weight of each channel and each antenna. Weight calculation unit for calculating 62, communication request response signal generating unit for generating communication request response signal S62, 63 for weight Controls weights of each antenna based on the distribution S61, generation and weighted signal S63 in the communication request response signal S62, a weight control unit for generating a reception signal S65 by weighting and combining the antenna outputs S64.

  The operation of this embodiment will be described. A data transmission requesting station (hereinafter referred to as station A) that has generated a transmission request generates a communication request signal S52 and transmits it from the antenna 55. At this time, the weight control is usually not performed. The data receiving station (hereinafter referred to as B station) that has received the communication request signal estimates the transmission path between the transmitting antenna 55 and the receiving antenna 56 using the antenna output S56 of the communication request signal, and generates a transmission path response S57. Based on the transmission path response S57, the communication channel search unit 58 checks the state of each communication channel (beam) and generates channel state information S58. Although the maximum number of communication channels is defined by the number of transmission / reception antennas, the use channel selection unit 59 selects a channel to be used for communication between the A station and the B station based on the state of each channel. Further, the power distribution calculation unit 60 calculates the power distribution of each channel from various information about each used channel so that the most efficient communication is possible, and then the weight calculation unit 61 includes the power allocation channel. The antenna weight S61 at the time of data transmission / reception is calculated from the information S60. Thereafter, the communication request response signal generation unit 62 generates a communication request response signal S62 that is orthogonal to each channel, performs weighted synthesis using the calculated antenna weight S61, and transmits the weighted signal S63 toward the station A. . In the station A, the weight analysis unit 54 can know the communication channel (beam) used by analyzing each antenna output S55 when the communication request response signal S62 from the station B is received. Based on this, the antenna weight S56 of each channel is determined. The weight control unit 53 performs weighting according to the weight information S56 and starts data transmission. In the B station, the received information S64 from the A station is weighted and synthesized with the already set weight S61, and the received signal S65 is extracted. When the transmission path information is known in the A station, the communication request response signal S62 does not need to be orthogonal for each channel.

  As described above, in the present embodiment, it is possible to synchronize use channels between transmitting and receiving stations by adopting the configuration as described above, and efficient communication using a plurality of channels (beams). Is possible.

  In the following embodiments, various examples for realizing this configuration will be shown.

Embodiment 6 FIG.
In the present embodiment, a method for improving the efficiency of signal transmission using a specific transmission / reception weight in the transmission method using a plurality of transmission / reception beams of the fifth embodiment will be described. FIG. 6 shows the configuration of the transmission / reception station in this embodiment. In FIG. 6, 5 is a transmission station (transmission weight multiplication device), 6 is a propagation path, and 7 is a reception station (reception weight multiplication device).

In the present embodiment, transmission beam forming is performed using eigenvectors of the matrix H ^H H. Here, the matrix H ^H is a complex conjugate transposed matrix of the matrix H. Therefore, the properties of the matrix H ^H H are outlined below. The eigenvalue of the matrix H ^H H is λ _{n, the} eigenvector is e _n (n = 1, 2,..., N),
E = [e ₁ , e ₂ ,..., E _N ]
Λ = diag [λ ₁ , λ ₂ ,..., Λ _N ]
Is defined, the following equation holds.
H ^H H = EΛE
Here, H ^H H is a Hermitian matrix, and the matrix E is a unitary matrix. Therefore, the following relationship is satisfied.
E ^H E = EE ^H = I
The method of the present embodiment will be described using such matrix properties.

In this embodiment, it transmits the transmission weight as w _{n =} e _n at the weight controller 53. At this time, the received vector x (p) = [x ₁ (p),..., X _M (p)] ^T is given by the following equation.
x (p) = Σ _{k = 1} ^K a _k s _k (p) + z (p)
a _k = H w _k
Here, a _k is an equivalent propagation vector of the signal k viewed from the receiving station. Matrix _{A = [a 1, ···,} a N], W = [w 1, ···, w N] By defining, following equation holds.
A ^H A = W ^H H ^H H W
= E ^H H ^H H E
= Λ
From this result, it can be seen that the equivalent propagation vectors a _k are orthogonal to each other. Therefore, when array signal processing is performed between the antennas using the reception weight v _k = a _k ^* in the weight control unit 63, the output k for the signal k is y _k (p) = a _k ^H x (p).
= Λ _k s _k (p) + a _k ^H z (p)
And other signals are removed. Thus, interference transmission weight in weight control unit 53 by a _w n = _{e n,} to _v k = receiving weight in weight control section 63 _(H w ^{k) *,} mutually the K transmission signal Can be transmitted. This communication channel is hereinafter referred to as an orthogonal channel. By this method, it is possible to cope with higher speed transmission than the conventional method without deterioration of communication quality. When H is added from the left side of the eigen equation H ^H Hw _k = λ _k w _k , the relationship of H ^* H ^T v _k = λ _k v _k is established. Therefore, the transmission weight _{v k} has become a eigenvectors of ^H * ^{H T.} Note that, H ^* is the conjugate transpose of the matrix H, H ^T is a transposed matrix of the matrix H.

Here, in order to grasp the communication capacity of the present embodiment, the communication capacity is measured based on the Shannon capacity index. For simplicity, it is assumed that meets state noise vector are uncorrelated with each antenna of the receiving station, namely the relationship between ^{E [z z H] = P} z I. Further, it is assumed that K = N and the transmission power of the same power Ps is used for each transmission beam. At this time, from the orthogonality between _{a k,} the noise _a ^k H z at each output (p) is uncorrelated. Eventually, the signal power of the signal k is Psλ _k ^{2 and the} noise power is P _z λ _k , and the SINR of the kth orthogonal channel formed by the transmission weight w _{k and the} reception weight v _k is given by (Ps / P _z ) λ _k . It is done. N orthogonal channels are equivalently formed between the transmitting and receiving stations, and the communication capacity is given by the following equation.
C = Σ _{k = 1} ^K log ₂ (1+ (Ps / P _z ) λ _k )
In the conventional beam forming, the communication capacity is equivalent to this one channel, so the communication capacity is greatly improved by this method.

The communication capacity when space time coding is used is given by the following equation.
C = log ₂ det (I + (P _s / P _z ) H ^H H)
= Σ _{k = 1} ^N log ₂ (1+ (P _s / P _z ) λ _k )
Thus, when the same transmission power is allocated to each beam, the communication capacity is the same as when space time coding is used.

  In this embodiment, the weight is determined using the information of the propagation vector H. Various methods have been considered so far for estimating the propagation vector H, but here, any existing method may be used to estimate H. Further, it is not always necessary to make all the powers of the transmission beams constant. If the power for each transmission beam is changed (under constant total transmission power), the overall communication capacity can be further improved. In this case, the communication capacity can be further improved as compared with the case where space time coding is used.

  As described above, when the method of the present embodiment is used, a communication capacity larger than that of the conventional beam forming method is possible. In addition, it is possible to ensure a communication capacity equal to or higher than that of a method using space time coding.

  As described above, according to the present embodiment, it is possible to construct a plurality of orthogonal channels without mutual interference by determining transmission weights using propagation path information.

Embodiment 7. FIG.
In the present embodiment, an example of a method for estimating the propagation path H in the transmission method using the plurality of transmission / reception beams of the above-described fifth embodiment will be described. FIG. 7 shows the configuration of the transmission / reception station in this embodiment. In FIG. 7, 6 is a propagation path, 7 is a receiving station (receiving weight multiplier), and 20 is a receiving filter corresponding to a transmission signal.

In the transmitting station, when estimating the propagation path H, the communication request signal generating unit 52 transmits a different signal for each antenna. At this time, the transmission signals are set so that the signals to be transmitted are orthogonal within the range of sample 1 to sample p0. That is, transmission signals s ₁ (t),..., S _k (t),..., S _N (t) corresponding to each antenna satisfy the relationship of the following equation.
When Σ _{p = 1} ^{p = po} s _k1 (p) s _k2 (p) ^* = p0 k1 = k2
= 0 In other cases, such an orthogonal signal is transmitted from each antenna. At this time, each transmission signal has the same symbol time and is transmitted from the antenna at the same timing.

A reception signal x _m (p) at the reception antenna m is expressed by the following equation.
x _m (p) = Σ _{n = 1} ^N h _mn s _n (p) + z _m (p)
In the propagation path estimation unit 57 following each reception antenna 56, a matched filter corresponding to each transmission signal is prepared. The output g (m, k) of the matched filter 20 corresponding to the receiving antenna m and the signal k is given by the following equation.
g (m, k) = (1 / p0) Σ _{p = 1} ^po s _k (p) ^* x _m (p)
= H _mk + (1 / p0) Σ _{p = 1} ^po s _k (p) ^* z _m (p)
The second term is a noise term, and the noise becomes smaller as p0 is larger.

  Thus, propagation path estimation can be performed by transmitting an orthogonal signal from each antenna on the transmission side.

Here, a method has been described in which a signal is transmitted from the transmission side and the propagation path estimation unit 57 on the reception side performs propagation path estimation. Based on the obtained propagation path information, the reception weight can be determined. An example of the weight determination method is shown in the sixth embodiment, but it can be applied to other weight determination methods. Incidentally, in accordance with the sixth embodiment, using the estimated H, performs eigenvalue decomposition of the matrix H ^* H ^T in weight calculation unit 61, the M eigenvectors and receive weights for each beam. This weight determination method is shown in FIG. Note that it is not always necessary to use all M weights, and a reception beam can be formed within a range of 1 to M.

  Up to this point, the orthogonal signal is transmitted from the transmission side (A station), and the propagation path is estimated on the reception side (B station). Conversely, the same control can be performed from the receiving side (B station) to the transmitting side (A station). That is, an orthogonal signal is transmitted from each antenna of station B, and propagation path estimation is performed on the transmission side (station A). FIG. 8 shows the configuration of the transmitting / receiving station in this control. In this way, it is possible to perform channel estimation between the A and B stations.

Incidentally, in accordance with the sixth embodiment performs eigenvalue decomposition of the matrix H ^{H H} using the estimated H, a transmission weight of each beam at the N eigenvectors information communication. This weight determination method is shown in FIG. It is not always necessary to use all N weights, and a transmission beam can be formed within a range of 1 to N.

  As described above, by grasping the propagation path information between the A and B stations, the transmission / reception weight can be determined using the propagation path estimation result H.

  As described above, according to this embodiment, it is possible to construct a plurality of orthogonal channels that do not interfere with each other by determining reception weights using propagation path information.

Embodiment 8 FIG.
The present embodiment relates to an effective transmission / reception weight determination method when there is an interference signal on the receiving side in the transmission method using a plurality of transmission / reception beams of the fifth embodiment. FIG. 9 shows the configuration of the transmission / reception station in this embodiment. In FIG. 9, 5 is a transmission station (transmission weight multiplication device), 6 is a propagation path, and 7 is a reception station (reception weight multiplication device).

In the present embodiment, similarly to the first embodiment, the reception vector x (p) = [x ₁ (p),..., X _M (p)] ^T is given by the following equation.
x (p) = Σ _{k = 1} ^K H w _k s _k (p) + z (p)
Here, z (p) is an interference noise vector and includes not only noise but also interference components. In addition, there is a correlation between the antennas, and the relationship R _IN = E [z (p) z (p) ^H ] is satisfied.

In this embodiment, a reception beam is formed on the reception side using eigenvectors of R _IN ^{−1 *} H ^* H ^T. On the transmission side, a transmission beam is formed using the eigenvector of H ^H R _IN ⁻¹ H. That is, each transmission / reception vector satisfies the following equation.
^{_{H H R IN -1 Hw n =}} ρ n w n
R _IN ^{−1 *} H ^* H ^T v _n = ρ _n v _n
Here, R _IN is an interference noise matrix at the receiving station. In addition, ρ _n represents an eigenvalue, and H ^H R _IN ⁻¹ H and R _IN ^{−1 *} H ^* H ^T have the same eigenvalue.

When such a weight is used, it is possible to receive a signal from a desired transmitting station with high quality while suppressing interference even when an interference signal is present at the receiving station. Various methods for estimating R _IN and H at the receiving station are conceivable, but any method may be used.

In addition, reception quality may be obtained in which a correlation matrix R = E [x (p) x (p) ^H ] of all received signals is used instead of R _IN . FIG. 10 shows the configuration of the transmission / reception station in this embodiment. In this case, the eigen equations satisfied by the transmission / reception weights are respectively R ^{−1 *} H ^* H ^T v _n = ρ _n v _n
It becomes. Even with such a configuration, it is possible to receive a signal from a desired transmitting station with high quality while suppressing interference even when an interference signal is present at the receiving station. Various methods for estimating R and H at the receiving station are conceivable, but any method may be used.

  As described above, in the present embodiment, by determining the transmission weight using the propagation path information, even when there is an interference component correlated between antennas at the receiving station, a plurality of mutual interferences are present. It is possible to construct no orthogonal channels.

Embodiment 9 FIG.
The present embodiment relates to a method that enables high-speed weight calculation, among the reception weight forming methods in the eighth embodiment. FIG. 13 shows the configuration of the transmission / reception station in this embodiment.

In this embodiment, when determining the reception weight before the start of information communication, a signal different for each antenna is transmitted from the transmitting station. At this time, the transmission signals are set so that the transmission signals are orthogonal within the range of sample 1 to sample p0. That is, transmission signals s ₁ (t),..., S _k (t),..., S _K (t) corresponding to each antenna satisfy the relationship of the following equation.
When Σ _{p = 1} ^{p = po} s _k1 (p) s _k2 (p) ^* = p0 k1 = k2
= 0 In other cases, such an orthogonal signal is transmitted from each antenna. At this time, each transmission signal has the same symbol time and is transmitted from the antenna at the same timing.

A reception signal x _m (p) at the reception antenna m is expressed by the following equation.
x _m (p) = Σ _{n = 1} ^N h _mn s _n (p) + z _m (p)
Here, z _m (p) is an interference noise component and has a correlation between antennas.

In the propagation path estimation unit 57 following each reception antenna, a matched filter corresponding to each transmission signal is prepared. The output g (m, k) of the matched filter corresponding to the receiving antenna m and the signal k is given by the following equation.
g (m, k) = (1 / p0) Σ _{p = 1} ^po s _k (p) ^* x _m (p)
= H _mk + (1 / p0) Σ _{p = 1} ^po s _k (p) ^* z _m (p) (2)
The second term is an interference noise term, and the noise becomes smaller as p0 is larger. Thus, the propagation path H can be estimated by transmitting orthogonal signals from each antenna on the transmission side.

Further, the correlation matrix of the received signal is estimated by the following equation.
Φ = Σ _{p = 1} ^{p = p1} x (p) x (p) ^H (3)
Here, the range of Σ in Equation (2) and Equation (3) may be different.

Here, a method has been described in which a signal is transmitted from the transmission side and the propagation path estimation unit 57 on the reception side performs propagation path estimation. Based on the obtained propagation path information, the reception weight can be determined. An example of the weight determination method is shown in the eighth embodiment, but it can be applied to other weight determination methods. Note that, based on the eighth embodiment, the weight calculation unit 61 performs eigenvalue decomposition of the matrix Φ ^{−1 *} H ^* H ^T using the estimated Φ and H, and the M eigenvectors are received weights of each beam. And This weight determination method is shown in FIG. Note that it is not always necessary to use all M weights, and a reception beam can be formed within a range of 1 to M.

  As described above, in the present embodiment, it is possible to determine the weight with high accuracy using the high-accuracy channel estimation.

Embodiment 10 FIG.
The present embodiment relates to a method different from the ninth embodiment that enables high-speed weight calculation among the reception weight forming methods in the eighth embodiment. Specifically, the correlation matrix calculation method is different. FIG. 19 shows the configuration of the transceiver in this embodiment.

In this embodiment, when determining the reception weight before information communication start, transmit signal _s 1 which is different from the transmitter to each antenna _{(t), ···, s k} (t), ···, s K ( t) is transmitted from each antenna. At this time, each transmission signal has the same symbol time and is transmitted from the antenna at the same timing.

A reception signal x _m (p) at the reception antenna m is expressed by the following equation.
x _m (p) = Σ _{n = 1} ^N h _mn s _n (p) + z _m (p)
Here, z _m (p) is an interference noise component and has a correlation between antennas. Here, p = 1 is a start sample of the transmission signal s _n (p), and s _n (p) = 0 when p = <0.

In the propagation path estimation unit 57 (see FIG. 18) following each reception antenna, a matched filter corresponding to each transmission signal is prepared. The output g (m, k) of the matched filter corresponding to the receiving antenna m and the signal k is given by the following equation.
g (m, k) = (1 / p0) Σ _{p = 1} ^po s _k (p) ^* x _m (p)
= H _mk + (noise interference term)
The second term is an interference noise term, and the noise becomes smaller as p0 is larger. In this way, by transmitting a signal from each antenna on the transmission side, the (m, k) element of the propagation path H is estimated as g (m, k).

In this embodiment, the correlation matrix of the received signal is estimated by the following equation.
Φ _IN = Σ _{p <= 0} x (p) x (p) ^H
Here, only the interference noise component is estimated using a section where there is no transmission signal s _k (p) of p <= 0.

The eigenvalue decomposition of the matrix Φ _IN ^{−1 *} H ^* H ^T is performed from the calculation result as described above, and M eigenvectors are set as the reception weights of the respective beams. This weight determination method is shown in FIG. Note that it is not always necessary to use all M weights, and a reception beam can be formed within a range of 1 to M.

In this embodiment, the transmission signal _{s 1 (t), ··· s} k (t), ···, using a non-existent section _s K (t), the correlation matrix [Phi _IN beforehand interference noise component calculate. Thus, by performing the correlation matrix calculation of interference noise components in advance, a highly accurate correlation matrix can be obtained. Further, it is possible to obtain a good reception weight and eigenvalues when eigenvalue decomposition of Φ _IN ^-1 H ^* H ^T.

Embodiment 11 FIG.
The present embodiment relates to a method for determining a transmission weight in the transmission scheme using a plurality of transmission / reception beams of the fifth embodiment. In this embodiment, the reception weight v _k is determined first, and the transmission weight is determined using the result. FIG. 14 shows a configuration of a transmitting / receiving station in the present embodiment.

When the reception weight v _{k of the} station B is determined, the reception station prepares a transmission signal r _k (p) in the communication request response signal generation unit 62 and multiplies the weight control unit 63 by the weight v _k already determined. Send. In the A station, a matching filter for the signal r _k (p) is prepared for each antenna, and the detection value q _kn at each antenna is vectorized (q _k = [q _k1 , q _k2 ,..., Q _kN ] ^T ). To do. Finally, the weight analysis unit 54 estimates the transmission weight as w _k = q _k ^* or w _k = q _k ^* / | q _k |. Here, | · | represents the norm of the vector. This method can be used regardless of how v _k is determined at the receiving station.

This relationship is described mathematically as follows. In the fifth to eighth embodiments, the transmission weight w _k and the reception weight v _k satisfy the following relationship.
v _k = (Hw _k ) ^*
That is, if V = [v ₁ ,..., V _K ], W = [w ₁ ,..., W _K ], it can be rewritten as
HW = V ^*
H ^H HW = H ^H V
WA = H ^H V ^*
W ^* Λ ^* = ^H T V
In this equation, the right side represents the received vector received at A station when performing signal transmission by the vector v _m from B station. In this way, the A station can determine the transmission weight using the signal from the B station.

  As described above, according to the present embodiment, a reception weight used for beam forming on the reception side is first determined, a signal is transmitted from the reception side using the reception weight, and the signal is received on the transmission side, By determining the transmission weight based on the received data, it is possible to efficiently determine the transmission weight with a small control amount.

Embodiment 12 FIG.
The present embodiment relates to the signal r _k (p) transmitted from each antenna of terminal B in the eleventh embodiment.

In the present embodiment, a signal orthogonal in time shown below is used as the transmission signal r _k (p).
Σ _{p = 1} ^{p = por} _k1 (p) r _k2 (p) ^* = p0 k1 = k2
= 0 In other cases, by using such an orthogonal signal, the channel A is estimated with higher accuracy.

The detailed signal processing at station A is shown below. Station A receives the following signals.
_{x A (p) = Σ n} = 1 N H T v n r n (p) + z A (p)
Here, z _A (p) represents a noise component in terminal A. When station A receives the signal, it uses the matched filter corresponding to signal r _k (p) to perform the correlation calculation of the following equation.
q _n = (1 / p0) Σ _{p = 1} ^por _k (p) ^* x _A (p)
= H ^T v _n + (noise component)
As described in Embodiment ^11, the relationship of ^{_{H T v n = λ * n}} w n *. Therefore, the transmission weight is estimated as w _k = q _k ^* or w _k = q _k ^* / | q _k |.

In the present embodiment, by simultaneously transmit signals in the time-orthogonal relation as a transmission signal from the B station from a plurality of beams, it can be estimated with good accuracy channel estimation vector q _n in A station .

Embodiment 13 FIG.
The present embodiment relates to a method of performing communication by selecting only some of the orthogonal channels (beams) in the transmission method using a plurality of transmission / reception beams of the fifth embodiment.

In the seventh embodiment, a method has been described in which a signal is transmitted from the transmission side and the propagation path estimation unit 57 on the reception side performs propagation path estimation. In this embodiment, the communication channel search unit 58, based on the estimation result in the channel estimation unit 57 performs eigenvalue decomposition of the matrix H ^* H ^T, and calculates the M eigenvalues lambda _k.

SINR of each orthogonal channel in the sixth embodiment is given by _{(Ps / P z) λ k} , showed that the relevant large as eigenvalues of the matrix ^H * ^{H T,} where with eigenvalue lambda _k is A determination is made whether the orthogonal channel is available. That is, to determine whether to use depending on the value of the eigenvalue lambda _k In use the channel selection section 59. As a specific determination method, a configuration in which the eigenvalue λ _k is used if it is equal to or greater than the threshold value λ _th and in other cases is not used can be considered. However, other determination methods may be used.

Next, the power distribution calculation unit 60 determines a necessary transmission power value using the selected eigenvalue λ _k and determines a transmission power value used in the orthogonal channel. When the power distribution calculation unit 60 does not perform special processing, equal power is distributed to the selected channel. It is also possible to change the modulation scheme or encoding method for each orthogonal channel. Also in this case, the modulation scheme or encoding method to be used is determined based on the eigenvalue λ _k . When no special processing is performed, a standard QPSK signal is selected.

  FIG. 20 shows an example of a method for determining transmission power, modulation scheme, and encoding method. As shown in this figure, the B station has a table for determining the transmission power, the modulation scheme, and the encoding method in correspondence with the eigenvalue λk. When the station B calculates the eigenvalue λk, the modulation system and the encoding method are determined according to the magnitude of the eigenvalue λk based on the table shown in FIG. In addition, although the case where the transmission power, the modulation scheme, and the encoding method are simultaneously determined is shown as an example in this figure, it is also possible to determine only a part of the transmission power, the modulation scheme, or the encoding method from the eigenvalue λk. .

When station B determines the selected orthogonal channel and the power distribution, modulation scheme, and encoding method used in that channel, the weight calculation unit 61 sets the reception weight to v _k as in the seventh embodiment. Here, the reception weight but is given as the eigenvector of the matrix H ^* H ^T, eigenvectors, the communication channel search unit 58, it is also possible to obtain simultaneously in calculating the eigenvalues of the matrix H ^* H ^T. Here, even if the weight calculation unit 61 performs the calculation independently, the result in the communication channel search unit 58 may be used.

Thus transmission and determines the reception weight v _k, B station to the method shown in Embodiment 11, was prepared the transmission signal r _{k (p)} in a communication request response signal generating unit 62, corresponding to the weight v _k A signal is transmitted to the A station using the beam. FIG. 21 shows an example of a signal format transmitted from the B station to the A station. In this transmission signal, after the transmission signal r _k (p), data related to the required transmission power, the required modulation method, and the required encoding method is further included. As shown in the eleventh embodiment, when the signal from the B station is received at the A station, the weight analysis unit 54 estimates the transmission weight as w _k = q _k ^* or w _k = q _k ^* / | q _k |. In addition, by receiving data related to the required transmission power, the required modulation method, and the required encoding method, it is possible to determine the transmission power, modulation method, and encoding method used during communication. Note that the signal format in FIG. 21 is an example, and other formats may be used.

Through such a series of operations, the transmitting / receiving station can select several channels from the orthogonal channels and use them for communication. Here, the transmission method of the seventh embodiment is used as an example, and a method of performing communication by selecting a beam according to the eigenvalue λ _k is shown. However, the interference signal shown in the eighth and ninth embodiments exists. If performs eigenvalue decomposition of the matrix Φ ^{-1 *} H ^* H ^T, similar beams selected according to the obtained eigenvalues [rho _n, transmission power, modulation scheme, the determination of the encoding method performed. Therefore, the beam selection, transmission power, modulation scheme, and coding method determination described in this embodiment can be applied to eigenvalue decomposition of the matrix Φ ^{−1 *} H ^* H ^T.

Embodiment 14 FIG.
In this embodiment, in the transmission method using a plurality of transmission / reception beams of Embodiment 13, the orthogonal channel used by the base station is recognized when only some orthogonal channels (beams) are selected for communication. It is about how to do.

In the thirteenth embodiment, station B determines a channel to be used in the used channel search unit. After determining the reception weight v _k , the B station prepares the transmission signal r _k (p) in the communication request response signal generation unit 62. At this time, the A station uses only the reception weight v _k corresponding to the use channel. to send signal _r k a (p) to.

In the station A, the weight analysis unit 54 receives a signal using the matched filter corresponding to the transmission signal r _k (p) (Embodiment 11) and calculates the vector q _k . The detected vector q _k is There are only vectors corresponding to the used channels. This is because only the transmission signal r _k (p) corresponding to the use channel is transmitted from the B station. Therefore, the station A can recognize the channel that the station B intends to use from the power level of the vector q _k detected by the weight analysis unit 54. In this case, A station rather than sending the control information by the power level of the vector q _k, can recognize the channel to be utilized.

Also, A station can determine the transmission weight w _k from the vector q _k usage channel, starts communication of information from the A station to B station using only available channel. If no special processing is performed, station A performs signal transmission with the same predetermined power in each orthogonal channel to be used.

  As described above, according to the present embodiment, it is possible to notify the other station of the channel to be used without using a control signal.

Embodiment 15 FIG.
In the present embodiment, in the transmission method using a plurality of transmission / reception beams of the thirteenth embodiment, when only a part of the orthogonal channels (beams) is selected and communication is performed, simultaneously with the orthogonal channels used by the base station The present invention relates to a method for recognizing transmission power and modulation method during information communication.

In the thirteenth embodiment, the B station determines a channel to be used in the used channel search unit 58. After determining the reception weight v _k , the B station prepares the transmission signal r _k (p) in the communication request response signal generation unit 62. At this time, the A station uses only the reception weight v _k corresponding to the use channel. A transmission signal r _k (p) is transmitted to. At this time, the transmission signal r _k (p) from the station B includes a required transmission power and a required modulation method for information communication. The method for describing the required transmission power and the required modulation scheme in the transmission signal r _k (p) follows a predetermined method. As an example, there is a method using spread spectrum. That is, the orthogonal transmission signal r _k (p) from each beam of the station B is used as a spread signal, and is transmitted by multiplying the information on the required transmission power and the required modulation method. In station A, the weight analysis unit performs despreading by receiving a signal using a corresponding matched filter, and extracts data related to the required transmission power and the required modulation scheme.

  With such a method, the station A can grasp the required transmission power and the required modulation method in each orthogonal channel to be used.

Embodiment 16 FIG.
The present embodiment relates to a method for performing access control simultaneously with a control method for determining transmission / reception weights in a MIMO system.

  FIG. 22 is a diagram for explaining a control method and an access method according to the present embodiment. In addition to terminals A and B that perform transmission and reception, terminals C and D exist. In the following, the weight control method and the access method of this embodiment will be described with the transmitting station as terminal A and the receiving station as terminal B. In the present embodiment, a request (REQ; request) signal is transmitted from terminal A to terminal B, and a channel notification (REP; report) signal from terminal B to terminal A is returned. A transmission / reception weight is determined using the two-stage signal transmission. FIG. 23 shows an example of a signal format used in the control of this embodiment. FIG. 23A shows an example of the REQ signal, and FIG. 23B shows an example of the REP signal. 24, 25, and 26 show the operation in each terminal during transmission of the REQ signal, the REP signal, and the communication signal, respectively, in the present embodiment.

  Hereinafter, this embodiment will be described. When the information to be transmitted is generated, the terminal A notifies the terminal B to that effect using a REQ signal. At this stage, the terminal A does not grasp the exact position of the terminal B, and there are terminals C and D in addition to the terminal B around the terminal A. Under such circumstances, terminal B is searched from terminals B, C, and D using the REQ signal, and a communication start request is made.

  As seen in FIG. 23A, the REQ signal is composed of a pilot signal portion and a control signal. Here, as an example of the pilot signal, there is a configuration in which a signal orthogonal in time is transmitted from terminal A shown in the ninth embodiment. Further, as an example of the control signal unit, there is a configuration including the user ID of the transmission / reception terminal shown in FIG. Here, the pilot signal portion of the REQ signal is a signal sequence known to the peripheral terminals B, C, and D.

  When the terminals B, C, and D existing around the terminal A detect the pilot signal portion of the REQ signal, the terminals B, C, and D recognize that the REQ signal has arrived. Next, each terminal confirms the control signal part of the REQ signal. By confirming the user ID of the control signal, it can be confirmed whether or not the REQ signal is a communication request to the own terminal.

  As shown in FIG. 24, when the terminal B confirms that the REQ signal is a communication request to its own terminal, the terminal B measures the propagation state between the terminals A and B using the pilot signal section. Also, orthogonal channels are calculated based on the propagation measurement results, and whether or not each orthogonal channel can be used is determined. The specific orthogonal channel calculation procedure includes the example described in the ninth embodiment.

  On the other hand, when the terminals C and D confirm that the REQ signal is not a request signal to the own terminal, the terminals C and D enter a standby state without performing the subsequent processing. In this way, by transmitting the REQ signal, a request signal can be sent from many terminals to the terminal B that is the object of communication.

  Terminal B calculates the orthogonal channel and determines the required transmission power, modulation scheme or encoding method. In addition, the terminal A is notified of necessary information using a REP signal. As an example of the REP signal, there is a configuration having a pilot signal part and a control signal part shown in FIG. As an example of the pilot signal unit, the configuration described in the eleventh embodiment can be considered. Further, as an example of the control signal unit, there is a configuration including a user ID and a requested transmission power, a requested modulation scheme, a requested encoding method, and the like shown in FIG. Note that the pilot signal portion of the REP signal is a signal sequence known to the peripheral terminals A, C, and D.

  As shown in FIG. 25, when the terminal A receives the REP signal, the terminal A determines the transmission weight by estimating the propagation coefficient. One example of a transmission weight determination method is the method described in the eleventh embodiment. Further, the peripheral terminals C and D also detect the REP signal and recognize that the terminal B is now ready to receive communication. At this time, the terminals C and D refrain from new transmission so as not to disturb the signal reception of the terminal B. That is, since terminals C and D refrain from new transmission after receiving the REP signal, terminal B can perform stable communication without interference (FIG. 26).

  As described above, the transmission / reception wait control is performed by the control using the REQ signal and the REP signal, and at the same time, the access control is performed. Specifically, terminal A searches terminal B by the REQ signal. At the same time, terminal B performs channel estimation and orthogonal channel determination using the REQ signal. In addition, terminal B notifies terminal A of data necessary for communication in the REP signal. At the same time, new communication is stopped at the terminals C and D. Terminals A and B can perform stable communication by stopping the new communication of terminals C and D.

  Thus, by performing access control simultaneously with weight control using the REQ signal and the REP signal, it becomes possible to search for a target terminal from among a large number of terminals and perform stable communication during communication. Such control enables stable communication even in a distributed network environment found in a wireless LAN.

  Note that, as shown in the present embodiment, the terminal B transmits a REP signal to the terminal A to simultaneously make a communication stop request to the peripheral terminals C and D. At this time, since the REP signal makes a communication stop request only to a spatial channel necessary for communication, communication stop of other terminals is not requested in a spatial channel that is not used. Therefore, communication is stopped only in a necessary space area, and unnecessary communication stop of peripheral terminals is reduced.

  At present, in the field of wireless LAN, RTS (Request to send) / CTS (Clear to send) protocol is known as one method for requesting a communication stop of a peripheral terminal. In starting communication, a receiving terminal (receiving station) transmits a CTS (Clear to send) signal uniformly in all directions, and peripheral terminals that receive the CTS signal stop communication for a certain period of time.

  However, as seen in the present embodiment, unnecessary communication stop of peripheral terminals can be reduced by making a communication stop request only to the necessary spatial channels for each direction. This communication stop control can be applied in any environment where the receiving station performs beam forming.

  In the present embodiment, a case has been described in which the communication of the other terminals C and D is stopped when the transmitting station and the receiving station use a plurality of antennas. Is not limited to that case. The communication stop control method is not limited to the above-described embodiment, and can be applied to any environment where the receiving station performs beam forming, including the case where the transmitting station and the receiving station use a single antenna.

Embodiment 17. FIG.
The present embodiment relates to a method for realizing a MIMO system in a multicarrier communication system.

  Recently, in wireless communication, there is a high demand for a system capable of high-speed transmission and high-speed movement, and it is necessary to transmit a broadband signal in a radio frequency band. As for broadband signal transmission, a multi-carrier scheme that performs parallel signal transmission using a plurality of carriers at the same time has attracted particular attention. In the multi-carrier transmission method, low-speed data is arranged in parallel on the frequency and transmitted simultaneously using different carriers. The transmission speed is improved by performing parallel transmission of signals.

  FIG. 27 shows a basic configuration diagram of a multicarrier communication system. As shown in the figure, the signal transmission unit multiplexes a plurality of signals on a plurality of different frequencies and transmits the signals. On the receiving side, signals multiplexed on a plurality of different frequencies are separated and used as received signals for each carrier. FIG. 28 shows a signal multiplexed on a plurality of carriers. As shown in the figure, the signals multiplexed by the multicarrier signal transmission unit are multiplexed and transmitted at a plurality of frequencies. At this time, signals transmitted on each carrier can be handled independently. That is, as in the case of single carrier transmission, each carrier can be handled individually.

  Therefore, although Embodiments 1 to 16 have been described for the case of single carrier transmission, the same signal processing can be applied to a multicarrier transmission system.

  FIG. 29 shows a signal processing configuration in which the MIMO system of the present invention is applied to a multicarrier transmission system. As shown in the figure, by configuring the MIMO system shown in Embodiments 1 to 16 for each carrier, the MIMO system of the present invention can be applied to a multicarrier transmission scheme. Moreover, by applying to a multicarrier transmission system, high-speed transmission using the frequency and the space domain effectively becomes possible.

  Since this invention is comprised as mentioned above, there exist the following effects.

  According to the present invention, N transmission signals are copied N times, multiplied by different transmission weights, and K signals are combined to form N transmission beams for transmission. One or more transmitting stations and the transmitted N transmission beams are received as K reception vectors made up of M components, each of which is multiplied by a different reception weight, and each of them is M Since the wireless transmission apparatus includes one or more receiving stations that form K reception beams by combining signals, a plurality of signals can be simultaneously transmitted in parallel by using a plurality of transmission / reception beams. Become.

  In addition, since the receiving weight of the receiving station is determined using the MMSE combining standard or the maximum ratio combining method, it is possible to receive a high-quality signal by using a receiving beam weight calculation method suitable for signal reception. It becomes.

  In addition, since a common correlation matrix is used in the multiplication operation of the reception weights in the individual reception beams of the reception station, by using a common correlation matrix calculation in the weight calculation when forming a plurality of reception beams, The amount of calculation can be reduced.

  In addition, since the transmission weights used in the transmission station are orthogonal to each other, transmission using transmission weights orthogonal to each other in the transmission station allows mutual transmission without using propagation information or the like. It is possible to make the channel nearly orthogonal.

In addition, the transmitting station has N transmitting antennas, the receiving station has M receiving antennas, and one transmitting antenna n to N receiving antennas from M transmitting antennas. The propagation coefficient to m is represented as h _mn , the propagation characteristic between transmitting and receiving stations is represented as a matrix H = [h _mn ], the correlation matrix between antennas of interference components is represented as R _IN , and the correlation matrix between antennas of all received signals is represented as R. Sometimes the matrix H ^H H, the matrix H ^H R _IN ⁻¹ H, or a plurality of eigenvectors of the matrix H ^H R ⁻¹ H are used as the transmission weights, so that the transmission weight is determined using the propagation path information. Thus, even when there are interference components having correlation between antennas at the receiving station, it is possible to construct a plurality of orthogonal channels without mutual interference.

In addition, the transmitting station has N transmitting antennas, the receiving station has M receiving antennas, and one transmitting antenna n to N receiving antennas from M transmitting antennas. The propagation coefficient to m is represented as h _mn , the propagation characteristic between transmitting and receiving stations is represented as a matrix H = [h _mn ], the correlation matrix between antennas of interference components is represented as R _IN , and the correlation matrix between antennas of all received signals is represented as R. Sometimes, the matrix H ^* H ^T , the matrix R _IN ^{−1 *} H ^* H ^T , or a plurality of eigenvectors of the matrix R ^{−1 *} H ^* H ^T are used as the transmission weights. By determining the transmission weight, it is possible to construct a plurality of orthogonal channels that do not interfere with each other even when there are interference components correlated between antennas at the receiving station.

In addition, the transmitting station has N transmitting antennas, the receiving station has M receiving antennas, and one transmitting antenna n to N receiving antennas from M transmitting antennas. The propagation coefficient to m is represented as h _mn , the propagation characteristic between transmitting and receiving stations is represented as a matrix H = [h _mn ], the correlation matrix between antennas of interference components is represented as R _IN , and the correlation matrix between antennas of all received signals is represented as R. Sometimes, using the matrix H ^* H ^T , the matrix R _IN ^{−1 *} H ^* H ^T , or a plurality of eigenvalues of the matrix R ^{−1 *} H ^* H ^T , the transmit / receive beam, modulation scheme, transmission power Alternatively, since the encoding method is determined, it is possible to select an orthogonal channel to be used using the propagation path information.

  Further, according to the present invention, each transmitting / receiving station includes a plurality of antennas, and signals that are temporally orthogonal between the antennas are individually transmitted for each antenna from one of the transmitting / receiving stations, and the other of the transmitting / receiving stations transmits the transmitted signal Is provided for each antenna, and propagation path estimation is performed using the output of the matched filter. Therefore, when performing propagation path estimation, transmission is performed using signals that are temporally orthogonal to each antenna. Highly accurate propagation path estimation becomes possible.

  Each of the transmitting and receiving stations includes a plurality of antennas, and signals that are temporally orthogonal between the antennas are individually transmitted for each antenna from one of the transmitting and receiving stations, and the other of the transmitting and receiving stations corresponds to the transmitted signal. Since a matched filter is provided for each antenna and propagation path estimation is performed using the output of the matched filter, highly accurate weight determination can be performed using highly accurate propagation path estimation using a matched filter.

  Further, the reception weight to be used in the receiving station is first determined, a signal is transmitted from the receiving station using the receiving weight, the signal is received by the transmitting station, and the received data is Since the transmission weight to be used at the transmission station is determined at the same time, the transmission weight can be determined efficiently with a small control amount.

  In addition, when transmitting a signal from the receiving station using the receiving weight, the control signal is used to notify the other station of the channel to be used by transmitting the signal using only a preselected channel. The other station can be notified of the channel to be used without using.

  Further, when transmitting a signal from the receiving station using the reception weight, a required transmission power or transmission / reception beam in each transmission / reception beam at the time of information communication is added by adding a required transmission power or a required modulation method to the signal to be transmitted. Since the required modulation method is notified to the other station, the required transmission power and the required modulation method in each orthogonal channel can be notified.

  The present invention also provides a communication request signal generation unit that generates a communication request signal for requesting the other party to perform communication, and transmits the generated communication request signal to the other party and from the other party with respect to the communication request signal. An array antenna unit that receives the communication request response signal of the antenna, a weight analysis unit that analyzes the communication request response signal received at the array antenna unit and calculates a transmission weight of each antenna, and a calculation by the weight analysis unit And a weight control unit that controls the transmission / reception weight of each antenna based on the transmitted transmission weight, so that the use channel can be synchronized between the transmission / reception stations. Efficient communication using the channel becomes possible.

  Also, a transmission path estimation unit that analyzes transmission / reception weights of each antenna and estimates a transmission path between the array antennas of the transmission / reception station, and a communication channel search unit that searches for a usable communication channel from the estimated transmission path A used channel selecting unit that selects a channel to be used for actual communication from the searched usable communication channels, and a power distribution calculating unit that calculates a signal power distribution to each selected channel to be used. A weight calculation unit for calculating a reception weight for each antenna from the used channel information and power distribution information, a weight control unit for controlling a transmission / reception weight for each antenna based on the calculated reception weight, and Since it is a wireless transmission device provided with a communication request response signal generator for generating a communication request response signal for a communication request signal, It is possible to synchronize the used channel, it is possible to efficiently communication using multiple channels.

  In addition, since transmission weights and reception weights corresponding to a plurality of spatial channels used between transmission and reception are set according to the propagation path, highly accurate weight determination according to the propagation path is possible.

  In addition, since a control signal is transmitted from the transmitting station and the receiving station sets a plurality of spatial channels using the control signal, stable communication can be performed during communication.

  Further, the receiving station calculates, for each of the set spatial channels, a parameter value for measuring a reception weight and communication quality, and based on the parameter value, a spatial channel used for transmission and reception, Since the modulation method, transmission power, or encoding method is selected, stable communication can be performed during communication.

  In addition, since the receiving station transmits a control signal to the transmitting station using the selected spatial channel, the transmission weight in the transmitting station is determined based on the control signal, so that it is stable during communication. Communication can be performed.

  In addition, since both transmission / reception weight control and access control are performed based on a control signal transmitted between transmission and reception, a target terminal can be searched from a large number of terminals, and stable communication can be performed during communication. .

  Further, by transmitting a signal in all directions from the transmitting station, a desired receiving station is searched from among a plurality of receiving stations, and the searched receiving station directs a control signal notifying a use channel. Since it transmits to the said transmitting station using an antenna, the object terminal can be searched from many terminals, and the stable communication can be performed at the time of communication.

  Further, the control signal transmitted from the receiving station notifies the transmitting station of the use channel, and instructs other transmitting / receiving stations not to be transmitted / received to stop transmission. Since the generation of new communication from a non-terminal can be stopped, further stabilization of communication can be achieved.

  The present invention is also a wireless transmission device including a plurality of terminal devices for performing transmission / reception, wherein the terminal device instructs other terminals not to be transmitted / received to stop transmission for each usage direction. Since at least one transmission stop signal for transmission is transmitted, generation of new communication from a terminal that is not the target of transmission / reception can be stopped, so that communication can be further stabilized.

It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 1 of this invention. It is explanatory drawing showing the transmission-and-reception beam status in Embodiment 1 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 2 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 3 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 4 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 6 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 7 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 7 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 8 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 9 of this invention. It is explanatory drawing which showed the weight determination method in Embodiment 7 and 9 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 7 of this invention. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 9 of this invention. It is the block diagram which showed the structure of the radio transmission apparatus in Embodiment 11 of this invention. It is a basic block diagram of the transmission-and-reception signal processing structure using the space time coding in a prior art. It is a basic block diagram of the transmission / reception signal processing using the transmission / reception beam forming in a prior art. It is explanatory drawing which showed the transmission / reception beam formation of the transmission / reception signal processing using the transmission / reception beam formation in a prior art. It is the block diagram which showed the structure of the radio | wireless transmission apparatus in Embodiment 5 of this invention. It is the block diagram which showed the structure of the radio transmission apparatus in Embodiment 10 of this invention. It is explanatory drawing which showed the table for determining the transmission power in the radio | wireless transmission apparatus in Embodiment 13 of this invention, a modulation system, and an encoding method. It is explanatory drawing which showed an example of the signal format of the transmission signal in the radio | wireless transmission apparatus in Embodiment 13 of this invention. It is explanatory drawing which showed the control method and access method in the radio | wireless transmission apparatus in Embodiment 16 of this invention. It is explanatory drawing which showed an example of the signal format used by control of the wireless transmission apparatus in Embodiment 16 of this invention. It is explanatory drawing which showed the control method and access method in the radio | wireless transmission apparatus in Embodiment 16 of this invention. It is explanatory drawing which showed the control method and access method in the radio | wireless transmission apparatus in Embodiment 16 of this invention. It is explanatory drawing which showed the control method and access method in the radio | wireless transmission apparatus in Embodiment 16 of this invention. It is the block diagram which showed the basic composition of the multicarrier communication system. It is explanatory drawing which showed the signal multiplexed by the multiple carrier. It is explanatory drawing which showed the signal processing structure at the time of applying the radio | wireless transmission apparatus in Embodiment 1-16 of this invention to a multicarrier transmission system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Transmission signal, 2 Transmission antenna, 3 Reception antenna, 4 Reception signal, 10 Correlation matrix calculation part, 20, 21 Reception filter, 30 Channel estimation orthogonal signal, 31 Eigenvector calculation method, 32 Correlation matrix calculation part, 33 Propagation matrix Arithmetic unit.

Claims (1)

A wireless transmission device including a plurality of terminal devices for performing transmission and reception,
The terminal device transmits at least one transmission stop signal for instructing to stop transmission to another terminal device that is not a transmission / reception target for each usage direction.

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