JP2008211342A - Communication device and its communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the communication quality by an easier method and simpler hardware. <P>SOLUTION: An array antenna selecting portion 21 selects an array antenna 20-1 arranged on an axis-1. A weight computation portion 23 estimates channel response of interference waves and generates a weighting value (weight) of interference suppression. Similarly, the portion 23 generates a weight of interference suppression of array antennas 20-a, 20-b, 20-c, and 20-d on an axis-a, axis-b, axis-c, and so forth. Then, a communication quality determining portion 24 shown in Fig.1 selects an array antenna 20-i (i=1 to maximum number) having the highest communication quality for communication, on the occasion of communication with a Secondary system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication system that operates a plurality of systems at the same frequency, and a new system (Secondary system) that does not have priority has a secondary system while removing interference from a conventional system (Primary system) that has priority. The present invention relates to a communication apparatus and a communication method for compensating for communication degradation between the two.

  In recent years, with the widespread use of mobile phones, wireless LANs, and the like, techniques for performing transmission as fast as possible in a limited frequency band have been studied. In recent years, MIMO (Multiple Input Multiple Output) technology has attracted attention as means for realizing high-speed transmission in a limited band. MIMO uses array antennas for the transmitting side and the receiving side, respectively, and on the transmitting side, different data is transmitted for each antenna, and on the receiving side, different signals are restored by some interference cancellation / decoding technology. By doing so, it is a technique that remarkably improves the transmission speed at the same frequency as compared with transmission / reception between single antennas. Already introduced in wireless LAN systems and the like.

  However, in the MIMO technology, the number of transmission / reception antennas is a key for high-speed transmission. Therefore, in order to realize very high frequency utilization efficiency, a considerable number of antenna elements are required. When considering a small terminal, an increase in the number of antenna elements is not desirable because it increases the hardware scale.

  Cognitive radio technology has attracted attention as a means for effectively using frequencies by a method different from the MIMO technology (see, for example, Non-Patent Document 1). The cognitive radio technology is a technology in which a radio device recognizes a surrounding radio wave environment, selects an appropriate frequency band and uses it, thereby effectively utilizing an available frequency band. Since cognitive radio can effectively use frequencies and time that have not been attracting attention, the frequency per unit area can be greatly improved.

  FIG. 13 is a conceptual diagram for explaining the outline of the cognitive radio technology. In FIG. 13, 1-1 and 1-2 are two priority systems (Primary systems), and 2-1 to 2-6 are a plurality of cognitive systems (Secondary systems). Reference numeral 3 denotes a communicable area of the primary system. Reference numerals 4-1 and 4-2 denote antenna directivities of the primary systems 1-1 and 1-2, respectively.

In cognitive radio, the primary systems 1-1 and 1-2 that originally use a certain communication band and the frequencies and times that are not used by the primary systems 1-1 and 1-2 are monitored, and this information is obtained. There are secondary systems 2-1 to 2-6 that perform communication based on the above. Basically, the primary systems 1-1 and 1-2 can use a preferentially assigned communication band, and the secondary systems 2-1 to 2-6 can perform communication by themselves. By interfering with the primary systems 1-1 and 1-2, the efficiency of the primary systems 1-1 and 1-2 should not be reduced. In addition, the primary systems 1-1 and 1-2 cannot normally recognize the existence of the secondary systems 2-1 to 2-6.
S. Haykin, “Cognitive radio: Brain-empowered wireless communications”, vol.23, no.2, pp.201-220, Feb. 2005.

  In the above-described environment, basically, interference waves from the primary systems 1-1 and 1-2 are removed, and cognitive radio is realized without any problem unless interference is given to the primary systems 1-1 and 1-2. can do.

  FIG. 14 is a conceptual diagram for explaining interference removal by an array antenna in order to avoid interference of the primary system or prevent interference with the primary system. In the figure, the transmitting stations 5 and 6 and the receiving station 7 are primary systems such as the primary systems 1-1 and 1-2 shown in FIG. Further, the Secondary system 8 includes a plurality of nodes. Here, it is considered to avoid interference waves from the transmission stations 5 and 6 to the Secondary system 8. An adaptive array using an array antenna is known as means for avoiding interference from the primary systems 5 and 6.

  FIG. 15 is a block diagram showing a basic configuration of an adaptive array. 15, the transmitting station 10 corresponds to, for example, the transmitting stations 5 and 6 shown in FIG. 14, the interference source 11 corresponds to, for example, the transmitting station 6, and the receiving station 12 includes the Secondary system 8 shown in FIG. Corresponds to one of the nodes included in. As shown in FIG. 15, in the adaptive array, signals input to the plurality of antennas 13-1 to 13 -N are appropriately controlled by weighters 14-1 to 14 -N under the control of the control circuit 16. This is a technique for removing interference waves by multiplying weight values (weights) and combining them by an adder 15. Various methods for setting the weighting have been proposed, and details are disclosed in Document 1 (Kikuma, Adaptive Signal Processing by Array Antenna, Science and Technology Publishers, 1998). If this adaptive array is used at the time of reception, interference waves from other systems can be removed, and if it is used at the time of transmission, interference with other systems can be avoided.

  However, the following problems occur even when an adaptive array is used. This problem will be described with reference to FIGS. FIG. 16 is a conceptual diagram for measuring the communication quality of the Secondary system calculated assuming an environment where there is interference of the Primary system in order to show the problem. FIG. 17 is a conceptual diagram showing an example of the result. In FIG. 16, for simplification, the interference from the primary system of one station is considered. Further, the Secondary system has three transmission / reception stations (nodes # 1 to # 3), which are considered to communicate with each other.

  As shown in FIG. 14, if each node of the Secondary system 8 can remove the interference wave, the Secondary system 8 can communicate using the same frequency as the Primary systems 5 and 6. The Secondary system 8 uses a two-element array antenna. In this calculation, each channel # 1 to # 3 of the secondary system 8 estimates the channel response of the interference wave, and a weight for removing the interference wave is obtained based on the zero forcing rule.

FIG. 17 shows the directivity of the array antenna for removing interference formed by the nodes # 1 to # 3 and the channel capacity R in communication between nodes. The channel capacity R was obtained from the relationship R = log ₂ (1 + CINR). Here, CINR (communication quality: Carrier-to-Interference plus Noise Ratio) represents a ratio between desired wave power and interference wave + noise power. The higher this value, the better the communication quality. This fact is disclosed in, for example, the above-mentioned document 1. As shown in FIG. 17, when the communication partner node is located in the direction of the null formed in the interference wave and the grating null as a mirror image (in FIG. 17, communication in which node # 1 is transmission and node # 3 is reception) ) The characteristics are greatly degraded. Fij shown in FIG. 17 represents the response of the array antenna between the receiving node #i and the transmitting node #j. The communication from node # 1 to node # 3 is large and this response is small. Therefore, it can be confirmed that this grating null has an adverse effect on the characteristic deterioration of the Secondary system.

  It is necessary to solve this problem. However, when a linear array arranged on a straight line is used, not limited to two elements, if a null is formed in the interference wave, the array antenna is connected to the opposite side. A null is always formed. In order to avoid this, it has been proposed to use a circular array or a rectangular array. However, since the entire aperture is eventually smaller than that of the linear array, the linear array is basically effective for improving the interference removal capability with as few elements as possible. Therefore, there is a need for a technique that uses a linear array to compensate for deterioration in communication quality of the secondary system due to the grating.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication apparatus and a communication method that can improve communication quality with an easier method and with simpler hardware. Is to provide.

  In order to solve the above-described problems, the present invention provides N antenna elements, N (N ≧ 2) transmitters and receivers connected to each of the antenna elements, and the transmitter and receiver. In a communication device that is connected to a machine and weights each input signal based on the information of the input signal and then synthesizes the weighted input signal to remove the interference wave, it is linear on different axes. M array antenna groups having N antenna elements to be arranged (M ≧ 2), array selection means for selecting an array antenna to be used for communication among the array antenna groups, and the array antenna group Based on the obtained information of each received signal, the weight calculation means for calculating the weight value for removing the interference wave for each of the array antenna groups, and the array antenna group Based on the signal quality, among the M array antenna group, which is a communication apparatus characterized by what array antennas and a selection control means for determining whether to select the array selection means.

  In order to solve the above-described problem, the present invention provides a plurality of array antennas including at least two or more antenna elements, a selection unit that selects one of the plurality of array antennas, and a selection unit that selects the plurality of array antennas. A transmitter / receiver to which the antenna elements constituting the array antenna are connected, weighting calculating means connected to the transmitter / receiver to calculate a weighting value so as to make the interference signal zero from information of the received signal, and the weighting calculation The weighting value calculated by the means is multiplied by the reception signal received by the transceiver, and the weighting means for synthesizing the weighted reception signal, and the communication quality is determined based on the output synthesized by the weighting means Communication quality determination means for controlling the selection operation of the selection means so as to select an antenna element having good communication quality. A communication device, characterized by Bei.

  According to the present invention, in the above invention, the plurality of array antennas share a first array antenna in which two antenna elements are linearly arranged, and one antenna element of the two antenna elements, and A second array antenna comprising two antenna elements arranged in a straight line in a direction different from the first array antenna by approximately 90 degrees, wherein the selection means includes the first array antenna and the second array antenna. One of the two antenna elements that are not shared with the array antenna is selected.

  The present invention is the above invention, wherein the plurality of array antennas are composed of a combination of two antenna elements arranged at each vertex of the equilateral triangle among the three antenna elements arranged at the apex of the equilateral triangle. Each of the antenna elements includes a first array antenna, a second array antenna, and a third array antenna, and the selecting means is any two of the three antenna elements arranged at the apex of the equilateral triangle. It is characterized by selecting.

  The present invention is the above invention, wherein the plurality of array antennas are arranged at the center of the equilateral triangle among the three antenna elements respectively arranged at the apexes of the equilateral triangle and the antenna elements arranged at the center of the equilateral triangle. Each of the first array antenna, the second array antenna, the second array antenna, and the antenna elements disposed at the vertices of the equilateral triangle, each having an angle of approximately 120 degrees. The selection means selects any one of the three antenna elements arranged at the apex of the equilateral triangle.

  According to the present invention, in the above invention, the plurality of array antennas include three antenna elements arranged on an x-axis, a y-axis, and a z-axis that form an angle of approximately 90 degrees, respectively, and an x-axis, a y-axis, and a z-axis. Of the antenna elements arranged at the origin position of the axis, the antenna element is arranged at the origin position and the antenna elements arranged on the x-axis, y-axis, and z-axis, each of which is approximately 90 A first array antenna, a second array antenna, and a third array antenna having an angle of degrees, and the selection means includes three antennas arranged on the x-axis, y-axis, and z-axis. One of the antenna elements is selected from the elements.

  Further, in order to solve the above-described problem, the present invention provides a communication method for performing communication between a transmitting station and a receiving station, for each of a plurality of array antennas each including at least two antenna elements. Measuring a propagation channel and received power from a received signal received by an antenna element; calculating a weighting value for performing interference cancellation from the propagation channel; multiplying the received signal and the weighting value; The step of combining for each of the plurality of array antennas, the step of specifying an array antenna having a good communication quality based on the combined signal for each of the plurality of array antennas, and using the specified array antenna for communication And a step of selecting as an array antenna.

  According to the present invention, in the above invention, the plurality of array antennas share a first array antenna in which two antenna elements are linearly arranged, and one antenna element of the two antenna elements, and It is characterized by comprising a second array antenna composed of two antenna elements arranged in a straight line in a direction different from the first array antenna by approximately 90 degrees.

  The present invention is the above invention, wherein the plurality of array antennas are composed of a combination of two antenna elements arranged at each vertex of the equilateral triangle among the three antenna elements arranged at the apex of the equilateral triangle. Each includes a first array antenna, a second array antenna, and a third array antenna.

  The present invention is the above invention, wherein the plurality of array antennas are arranged at the center of the equilateral triangle among the three antenna elements respectively arranged at the apexes of the equilateral triangle and the antenna elements arranged at the center of the equilateral triangle. Each of the first array antenna, the second array antenna, the second array antenna, and the antenna elements disposed at the vertices of the equilateral triangle, each having an angle of approximately 120 degrees. 3 array antennas.

  According to the present invention, in the above invention, the plurality of array antennas include three antenna elements arranged on an x-axis, a y-axis, and a z-axis, each having an angle of approximately 90 degrees, and an x-axis, a y-axis, and a z-axis. Of the antenna elements arranged at the origin position of the axis, the antenna element is arranged at the origin position and the antenna elements arranged on the x-axis, y-axis, and z-axis, each of which is approximately 90 It is characterized by comprising a first array antenna, a second array antenna, and a third array antenna having an angle of degrees.

  According to the present invention, in the above invention, when the series of steps is set as a procedure A, the procedure A is performed at a receiving station, and the maximum communication quality by the selected array antenna is less than a predetermined threshold value, A relay station arranged between the transmitting station and the receiving station, performing the procedure A with the transmitting station and identifying an array antenna having good communication quality; and the receiving The station performs the procedure A with the relay station and specifies an array antenna with good communication quality, and the array antenna obtained in the first step and the second step And a step of communicating from the transmitting station to the relay station and from the relay station to the receiving station.

  According to the present invention, when an array antenna used for communication is selected from among M (M ≧ 2) array antenna groups having N antenna elements arranged linearly on different axes, an array antenna is selected. Based on the information of each received signal obtained from the group, a weighting value for removing the interference wave is calculated for each of the array antenna groups. Based on the communication quality obtained from the array antenna group, M pieces of It is determined which array antenna is selected from the array antenna group. Therefore, even if a plurality of linear arrays are arranged on a plurality of different axes, and array antennas arranged on different axes form interference cancellation in the same direction, utilizing the fact that grating nulls are formed in different directions, Selecting these antennas while confirming the communication quality between the nodes of the Secondary system provides the advantage that the communication quality can be improved by an easier method and simpler hardware. .

  Further, according to the present invention, when selecting one of a plurality of array antennas composed of at least two antenna elements, the weighting value is set so that the interference signal is zero based on the information of the received signal of each array antenna. The weighted value is multiplied by the received signal, the weighted received signal is combined, the communication quality is determined based on the combined output, and an antenna element with good communication quality is selected. Therefore, even if a plurality of linear arrays are arranged on a plurality of different axes, and array antennas arranged on different axes form interference cancellation in the same direction, utilizing the fact that grating nulls are formed in different directions, Selecting these antennas while confirming the communication quality between the nodes of the Secondary system provides the advantage that the communication quality can be improved by an easier method and simpler hardware. .

  Further, according to the present invention, a plurality of array antennas are shared by a first array antenna in which two antenna elements are linearly arranged and one antenna element of the two antenna elements, and the first array antenna is used. A second array antenna composed of two antenna elements arranged in a straight line in a direction different from the antenna by approximately 90 degrees, and two antenna elements not shared by the first array antenna and the second array antenna The array antenna is switched by selecting one of the antenna elements. Therefore, there is an advantage that communication quality can be improved by an easier method and simpler hardware.

  Further, according to the present invention, each of the plurality of array antennas includes a combination of two antenna elements arranged at each vertex of the equilateral triangle among the three antenna elements arranged at the apex of the equilateral triangle. One array antenna, second array antenna, and third array antenna are used, and the array antenna is switched by selecting any two of the three antenna elements arranged at the apex of the equilateral triangle. Therefore, there is an advantage that the number of selectable antenna combinations can be increased.

  Further, according to the present invention, an antenna arranged at the center of the equilateral triangle among the three antenna elements arranged at the apexes of the equilateral triangle and the antenna elements arranged at the center of the equilateral triangle according to the present invention. A first array antenna, a second array antenna, and a third array antenna, each of which is formed of a combination of an element and an antenna element disposed at each vertex of an equilateral triangle, each having an angle of approximately 120 degrees. The array antenna is switched by selecting any one of the three antenna elements arranged at the apex of the equilateral triangle. Therefore, there is an advantage that it can be realized more easily.

  In addition, according to the present invention, a plurality of array antennas are arranged with three antenna elements arranged on the x-axis, y-axis, and z-axis that form an angle of approximately 90 degrees, respectively, and the x-axis, y-axis, and z-axis. Of the antenna elements arranged at the origin position, each of the antenna elements arranged at the origin position and the antenna elements arranged on the x-axis, y-axis, and z-axis each has an angle of about 90 degrees. Select one of the three antenna elements arranged on the x-axis, y-axis, and z-axis as the first array antenna, the second array antenna, and the third array antenna. By doing so, the array antenna is switched. Therefore, there is an advantage that the influence of the grating null can be suppressed in a three-dimensional plane.

  In addition, according to the present invention, for each of a plurality of array antennas including at least two antenna elements, the propagation channel and the received power are measured from the received signal received by each antenna element, and interference is removed from the propagation channel. A weighted value for the received signal, the received signal and the weighted value are multiplied, combined for each of the plurality of array antennas, and for each of the plurality of array antennas, an array antenna having a good communication quality is obtained. Identify and select the identified array antenna as the array antenna to be used for communication. Therefore, even if a plurality of linear arrays are arranged on a plurality of different axes, and array antennas arranged on different axes form interference cancellation in the same direction, utilizing the fact that grating nulls are formed in different directions, Selecting these antennas while confirming the communication quality between the nodes of the Secondary system provides the advantage that the communication quality can be improved by an easier method and simpler hardware. .

  Further, according to the present invention, a series of steps is set as procedure A, and the procedure A is performed at the receiving station. When the maximum communication quality by the selected array antenna is equal to or lower than a predetermined threshold, the transmitting station The relay station arranged between the receiver and the receiving station performs the procedure A with the transmitting station, specifies an array antenna with good communication quality, and performs the procedure A with the relay station at the receiving station. And an array antenna with good communication quality is identified, and communication is performed from the transmitting station to the relay station and from the relay station to the receiving station using the array antenna obtained in the first step and the second step. . Therefore, there is an advantage that the influence of null due to the interference wave can be more reliably removed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

A. Basic Principle FIG. 1 is a block diagram for explaining the basic concept of the present invention. In FIG. 1, a plurality of array antennas 20-1, 20-a, 20-b, 20-c, 20-d,... Are arranged on different axes. The different axes mean, for example, the x axis, the y axis, and the z axis as a simple example. For example, different axes may be assumed on the xy plane where z = 0. The array antenna itself has a linear arrangement. In the illustrated example, the number of elements of the array antennas 20-1, 20-a, 20-b, 20-c, 20-d,.

  First, the array antenna selection unit 21 selects the array antenna 20-1 arranged on the axis -1, the weight calculation unit 23 estimates the channel response of the interference wave, and generates a weight value (weight) for interference removal. . Similarly, an interference removal weight is generated for the array antennas 20-a, 20-b, 20-c, 20-d,... On the axes -a, -b, -c,. Thereafter, when performing communication with the Secondary system, the communication quality determination unit 24 shown in FIG. 1 selects the array antenna 20-i (i = 1 to the maximum number) having the highest CINR.

  Here, the directivity formed by each array antenna 20-1, 20-a, 20-b, 20-c, 20-d,... Is always determined so that interference from other systems becomes zero. . However, the grating null formed by each array antenna 20-1, 20-a, 20-b, 20-c, 20-d,... Differs depending on the difference in the axis of the antenna arrangement.

  As an example, as shown in FIG. 2, the directivity when two array antennas arranged on the xy plane at intervals of 120 degrees form nulls in interference waves coming from the 45 degree direction will be described. FIG. 3 is a conceptual diagram showing the directivity of the array antenna in the situation shown in FIG. As apparent from FIG. 3, since the grating nulls of axis-1 to axis-3 are different, the communication quality can be improved if the communication quality determination unit 24 can select the antenna 20-i having the highest CINR. Here, the array antenna selection unit 21 selects the determined array antenna 20-i to perform communication. Thus, the above-described problems can be solved by the present invention.

B. First Embodiment Next, FIG. 4 is a block diagram showing a configuration of a communication device in a primary system according to a first embodiment of the present invention. In FIG. 4, the antenna elements # 1 and # 2 constitute one array antenna 30-1, and the antenna elements # 1 and # 3 constitute one array antenna 30-2. The array antenna 30-1 is disposed on the x axis, and the array antenna 30-2 is disposed on the y axis. However, the antennas are not necessarily arranged on the x-axis and the y-axis, and the feature is that these array antennas 30-1 and 30-2 are arranged at positions different by 90 degrees.

  Antenna element # 1 is directly connected to receiver 32-1. The antenna element # 2 and the antenna element # 3 are connected to the input terminal of the two-branch switch 31. The two-branch switch 31 switches the antenna element # 2 or the antenna element # 3 under the control of the Tsushin quality determination unit 36, which will be described later, and supplies a reception signal received by either one to the receiver 32-2. The transfer function estimation and weight calculation unit 33 estimates the transfer function based on the information of the received signals supplied from the receivers 32-1 and 32-2, and applies to each of the array antennas 30-1 and 30-2. On the other hand, a weight value (weight) for removing the interference wave is calculated.

  The weight multiplication and addition unit 34 multiplies each weighted value and each received signal, adds and synthesizes each, and obtains an array output signal. The memory 35 holds the combined array output signal. The communication quality determination unit 36 selects an array antenna with good communication quality (CINR), and controls the switching operation of the two-branch switch 31 so that the selected array antenna is selected.

  FIG. 5 is a conceptual diagram showing an example of an interference removal pattern by the array antenna according to the first embodiment. As can be seen from FIG. 5, if the positions of the array antennas 30-1 and 30-2 are different by 90 degrees, the direction of the grating null is greatly different. This is apparent from the antenna pattern shown in FIG. In this example, the antenna element # 1 is shared by both of the array antennas 30-1 and 30-2. By doing so, the antenna switching is substantially only between the antenna element # 2 and the antenna element # 3. Since such a two-branch switch 31 is quite commercially available, it is easy to realize. Therefore, the configuration shown in FIG. 4 has an advantage that it can be realized with a very simple hardware configuration. Hereinafter, the operation of the first embodiment will be described.

  FIG. 6 is a flowchart for explaining the operation of the communication apparatus according to the first embodiment. In the following processing, weights for eliminating interference between the x-axis (# 1 and # 2) and the y-axis (# 1 and # 3) are calculated. First, in FIG. 4, the number of array antennas N = 2 (step S1), the two-branch switch 31 is switched to the antenna element # 2 side (step S2), and the transfer function estimation and weight calculation unit 33 The received signal and the interference channel propagation channel information (propagation channel and received power) input to the antenna element # 2 are measured (step S3).

  Next, the transfer function estimation and weight calculation unit 33 forms a null in the interference wave by using, for example, a zero-forcing algorithm known as an adaptive array algorithm or an MMSE algorithm based on the measured propagation channel information. The weight is calculated (step S4). Thereafter, the weight multiplication and addition unit 34 multiplies the received signal and the weight, synthesizes them, and obtains an array output signal obtained from antenna element # 1, antenna element # 2, and (array antenna 30-1), This is stored in the memory (step S5).

  Next, it is determined whether N = 3 (step S6). If N = 3, N is incremented by 1 (step S7), the process returns to step S2, and the above-described processing is repeated. That is, similarly, the two-branch switch 31 is switched to the antenna element # 3 side, and an array output signal for removing interference between the antenna element # 1, the antenna element # 3, and the (array antenna 30-2) is obtained, and this is stored in the memory. Store.

  When N = 3, the communication quality determination unit 36 uses the array element # 1, the antenna element # 2, and the array output signal obtained from the (array antenna 30-1), the antenna element # 1, and the antenna element # 3. From the array output signal obtained from (1) and (array antenna 30-2), an array antenna with good communication quality (CINR) is selected. That is, either one of the selected antenna elements # 2 or # 3 is selected by the two-branch switch 31 (step S8), and communication is started (step S9).

  According to the first embodiment described above, even if a plurality of linear arrays are arranged on a plurality of different axes, and array antennas arranged on different axes form interference cancellation in the same direction, grating nulls are formed in different directions. By selecting these antennas while confirming the communication quality between the nodes of the Secondary system using the formation, the communication quality is improved with an easier method and simpler hardware. be able to.

B-1. First Modification FIG. 7 is a block diagram showing a configuration of a communication apparatus according to the first modification. Note that portions corresponding to those in FIG. 4 are denoted by the same reference numerals and description thereof is omitted. In the figure, antenna elements # 1, # 2, and # 3 are arranged so as to be located at the vertices of a triangle. The 3-input 2-output switch 31a has three types of array antennas (# 1, # 2), (# 2, # 3), (# 3, # 1) as antenna elements # 1, # 2, and # 3. It can be selected. In this case, the three-input two-output switch 31a is more complicated than the case shown in FIG. 4, but has an advantage that there are more combinations of antennas that can be selected instead.

B-2. Second Modification FIG. 8 is a block diagram showing a configuration of a communication apparatus according to the second modification. It should be noted that parts corresponding to those in FIG. In the figure, antenna elements # 2, # 3, and # 4 are arranged so as to be located at the vertices of an equilateral triangle, and are arranged such that antenna element # 1 is located at the center thereof. The three-input one-output switch 31b can select antenna elements # 2, # 3, and # 4 as three types of array antennas (# 1, # 2) (# 1, # 3) (# 1, # 4). It is like that.

  With this configuration, the number of antenna elements is larger than the configurations shown in FIGS. 4 and 7, but in the case of a small antenna such as a terminal, if only the antenna elements are used, the installation space and hardware There is an advantage that the 3-input 1-output switch 31b can be realized more easily than the 3-input 2-output switch 31a shown in FIG.

B-3. Third Modification FIG. 9 is a block diagram showing a configuration of a communication apparatus according to the third modification. It should be noted that parts corresponding to those in FIG. In the figure, antenna element # 1 is arranged to be located at the origin of the x, y, and z axes, and antenna elements # 2, # 3, and # 4 are respectively located on the x, y, and z axes. Is arranged. That is, in the first to third embodiments described above, the antenna elements are arranged on the plane, but in the fourth embodiment, array antennas are arranged on the x, y, and z planes, respectively. In this case, there is an advantage that the influence of the grating null can be suppressed on a three-dimensional plane.

C. Second Embodiment Next, a second embodiment according to the present invention will be described.
In the first embodiment or the first to third modifications described above, the influence of the grating null is suppressed only by switching the antenna element. However, in the first embodiment or the first to third modifications described above, each array antenna forms a null in the same direction as the interference wave direction as shown in FIG. 4, FIG. 7, FIG. 8, or FIG. To do. Therefore, when the desired wave direction and the interference direction completely coincide with each other, there is a possibility that the characteristics are deteriorated. Therefore, in order to solve this problem, the second embodiment described below is characterized in that a relay (relay) technique is used in combination with the first embodiment described above.

  FIG. 10 is a conceptual diagram for explaining the principle of relay (relay) communication. A relay (relay) is, for example, when communication quality between certain nodes (between a transmitting station 40 and a receiving station 41) deteriorates in an environment where many communication terminals such as a sensor network are arranged. This is a method of improving communication quality by using another node (relay station 42) as a relay node. Basically, when the communication quality is not bad, or when the characteristics can be sufficiently obtained only by the first embodiment, the use of such a relay (relay) reduces the throughput, but the problem here Is effective for avoiding communication in the direction in which the interference wave null is formed.

  FIG. 11 is a flowchart for explaining the operation of the communication apparatus according to the second embodiment. As shown in FIG. 11, steps S1 to S8 (referred to herein as flow A) are the same as those in the first embodiment, and thus description thereof is omitted. After the process of flow A, it is determined whether or not the communication quality (CINR) satisfies a predetermined threshold value α (step S10). The threshold value α depends on the system and has a value set for each system.

  When the communication quality (CINR) does not satisfy the threshold value, it is determined that the desired wave direction and the interference direction completely match, and relay (relay) is performed. That is, the flow A is executed between the transmission station 40 and the relay station 42 (step S11), the antenna pattern with the highest CINR in which the desired wave direction and the interference direction completely coincide with each other is selected (flow A), and Then, the flow A is executed between the relay station 42 and the receiving station 41 (step S12), and the antenna pattern with the highest CINR is selected (flow A). Then, communication is started between the transmitting station 40 and the receiving station 42 via the relay station 42 (step S13).

  According to the second embodiment described above, it is possible to more reliably remove the influence of null due to interference waves.

Next, the effect of the present invention when the method of the second embodiment is used will be described.
FIG. 12 is a conceptual diagram showing the cumulative probability of channel capacity when the environment shown in FIG. 16 is used. As shown in FIG. 12, according to the present invention (second embodiment), it can be confirmed that the communication capacity that can be realized is improved by about 10 bits / s / Hz as compared with the normal method. Furthermore, it can be confirmed that the communication capacity is improved by about 3 to 5 bits / s / Hz due to the effect of the array antenna gain as compared with the case where only the Secondary system performs communication. As described above, by using the present invention, it is possible to reduce deterioration in communication quality of the secondary system due to grating nulls from other systems or the influence of nulls.

It is a block diagram for demonstrating the basic concept of this invention. It is a conceptual diagram for demonstrating the directivity at the time of forming null in an interference wave. It is a conceptual diagram which shows the directivity of an array antenna. It is a block diagram which shows the structure of the communication apparatus in the Primary system by 1st Embodiment of this invention. It is a conceptual diagram which shows an example of the interference removal pattern by the array antenna by this 1st Embodiment. It is a flowchart for demonstrating operation | movement of the communication apparatus by this 1st Embodiment. It is a block diagram which shows the structure of the communication apparatus by the 1st modification. It is a block diagram which shows the structure of the communication apparatus by the 2nd modification. It is a block diagram which shows the structure of the communication apparatus by the 3rd modification. It is a conceptual diagram for demonstrating the principle of relay (relay) communication. It is a flowchart for demonstrating operation | movement of the communication apparatus by 2nd Embodiment by this invention. It is a conceptual diagram which shows the accumulation probability of the channel capacity for demonstrating the effect of this invention. It is a conceptual diagram for demonstrating the outline | summary of a cognitive radio | wireless technique. It is a conceptual diagram for explaining interference removal by an array antenna for avoiding interference of the Primary system or preventing interference with the Primary system. It is a block diagram which shows the basic composition of an adaptive array. It is a conceptual diagram for measuring the communication quality of the Secondary system calculated assuming an environment in which interference of the Primary system exists. It is a conceptual diagram which shows an example of the communication quality of the Secondary system calculated supposing the environment where the interference of a Primary system exists.

Explanation of symbols

20-1, 20-a, 20-b, 20-c, 20-d, ... array antenna 21 array antenna selection unit 22-1 to 22-N receiver 23 weight calculation unit (weighting calculation means, weighting means)
24 Communication quality judgment unit (selection control means)
31 2-branch switch (array selection means)
31a 3 input 2 output switch (array selection means)
31b 3 input 1 output switch (array selection means)
32-1, 32-2 Receiver 33 Transfer function and weight calculation unit (weighting calculation means)
34 Weight multiplication & addition unit (weighting means)
35 Memory 36 Communication quality judgment unit (selection control means)
40 transmitting station 41 receiving station 42 relay station # 1 to # 4 antenna element

Claims (12)

N antenna elements, N (N ≧ 2) transmitters and receivers connected to each of the antenna elements, connected to the transmitters and receivers, and based on input signal information In the communication device that weights each input signal and then combines the weighted input signals to remove interference waves,
A group of M (M ≧ 2) array antennas having N antenna elements arranged linearly on different axes;
Array selection means for selecting an array antenna to be used for communication from the array antenna group;
Weighting calculating means for calculating a weighting value for removing an interference wave for each of the array antenna groups based on information of each received signal obtained from the array antenna group;
Selection control means for determining which array antenna is to be selected by the array selection means among the M array antenna groups based on the communication quality obtained from the array antenna group. Communication device. A plurality of array antennas comprising at least two or more antenna elements;
Selecting means for selecting any of the plurality of array antennas;
A transceiver to which an antenna element constituting the array antenna selected by the selection means is connected;
A weight calculation means connected to the transceiver for calculating a weight value so as to make the interference signal zero from information of the received signal;
A weighting unit that multiplies the weighting value calculated by the weighting calculation unit by the reception signal received by the transceiver, and synthesizes the weighted reception signal;
Communication quality determining means for determining the communication quality based on the output synthesized by the weighting means and controlling the selection operation of the selecting means so as to select an antenna element having a good communication quality. A communication device. The plurality of array antennas are:
A first array antenna in which two antenna elements are linearly arranged;
A second array antenna comprising two antenna elements that share one antenna element and are arranged in a straight line in a direction that is approximately 90 degrees different from the first array antenna. ,
The selection means includes
The communication apparatus according to claim 2, wherein one of the two antenna elements not shared by the first array antenna and the second array antenna is selected. The plurality of array antennas are:
Of the three antenna elements arranged at the vertices of the equilateral triangle, each of the first array antenna, the second array antenna, and the third antenna is composed of a combination of two antenna elements arranged at the vertices of the equilateral triangle. And an array antenna
The selection means includes
The communication apparatus according to claim 2, wherein any two of the three antenna elements arranged at the apex of the equilateral triangle are selected. The plurality of array antennas are:
Of the three antenna elements arranged at the apex of the equilateral triangle and the antenna elements arranged at the center of the equilateral triangle, the antenna element arranged at the center of the equilateral triangle, and arranged at each vertex of the equilateral triangle Composed of a combination of antenna elements, each comprising an angle of approximately 120 degrees, each comprising a first array antenna, a second array antenna, and a third array antenna,
The selection means includes
The communication apparatus according to claim 2, wherein any one of the three antenna elements arranged at the apex of the equilateral triangle is selected. The plurality of array antennas are:
Of the three antenna elements arranged on the x-axis, y-axis, and z-axis that form an angle of approximately 90 degrees, and the antenna elements arranged at the origin positions of the x-axis, y-axis, and z-axis, the origin position A first array antenna comprising a combination of the antenna elements arranged on the x-axis, the y-axis, and the z-axis, each having an angle of about 90 degrees; It consists of an array antenna and a third array antenna,
The selection means includes
The communication apparatus according to claim 2, wherein any one of the three antenna elements arranged on the x-axis, the y-axis, and the z-axis is selected. A communication method for performing communication between a transmitting station and a receiving station,
Measuring a propagation channel and received power from a received signal received by each antenna element for each of a plurality of array antennas composed of at least two antenna elements;
Calculating a weighting value for performing interference cancellation from the propagation channel;
Multiplying the received signal by the weighting value and combining each of the plurality of array antennas;
For each of the plurality of array antennas, identifying an array antenna with good communication quality based on a synthesized signal;
Selecting the identified array antenna as an array antenna to be used for communication. The plurality of array antennas are:
A first array antenna in which two antenna elements are linearly arranged;
It consists of a second array antenna that consists of two antenna elements that share one antenna element of the two antenna elements and that are linearly arranged in a direction that is approximately 90 degrees different from the first array antenna. The communication method according to claim 7. The plurality of array antennas are:
Of the three antenna elements arranged at the vertices of the equilateral triangle, each of the first array antenna, the second array antenna, and the third antenna is composed of a combination of two antenna elements arranged at the vertices of the equilateral triangle. The communication method according to claim 7, further comprising: an array antenna. The plurality of array antennas are:
Of the three antenna elements arranged at the apex of the equilateral triangle and the antenna elements arranged at the center of the equilateral triangle, the antenna element arranged at the center of the equilateral triangle, and arranged at each vertex of the equilateral triangle 8. A combination of antenna elements, each comprising an angle of approximately 120 degrees, each comprising a first array antenna, a second array antenna, and a third array antenna. Communication method. The plurality of array antennas are:
Of the three antenna elements arranged on the x-axis, y-axis, and z-axis that form an angle of approximately 90 degrees, and the antenna elements arranged at the origin positions of the x-axis, y-axis, and z-axis, the origin position A first array antenna comprising a combination of the antenna elements arranged on the x-axis, the y-axis, and the z-axis, each having an angle of about 90 degrees; 8. The communication method according to claim 7, comprising an array antenna and a third array antenna. The series of steps is defined as procedure A, and the procedure A is performed at the receiving station.
If the maximum communication quality by the selected array antenna is below a predetermined threshold,
A first step of performing the procedure A between the transmitting station and the transmitting station at a relay station arranged between the transmitting station and the receiving station to identify an array antenna having a good communication quality;
A second step of performing the procedure A with the relay station at the receiving station to identify an array antenna with good communication quality;
Using the array antenna obtained in the first step and the second step, communicating from the transmitting station to the relay station and from the relay station to the receiving station. The communication method according to claim 7.

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