JP2001230711A - Communication method in mobile communication system and radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication method for easily realizing radio communication by forming an antenna directional pattern by an array antenna between a base station and mobile equipment. SOLUTION: By this communication method in a mobile communication system, at the time of communication between the base station and the mobile equipment in the mobile communication system, the communication is performed by forming the antenna directional pattern provided with a single main beam and plural side lobes extended in directions different from the main beam for which all the side lobes become a level for not practically contributing to the communication in the base station and the communication in the other mobile equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method in a mobile communication system, and more particularly, to a wireless communication method in which an antenna array pattern is formed by an adaptive array antenna between a base station and a mobile station in a mobile communication system. The communication method when performing the communication.

[0002] The present invention also relates to a radio communication apparatus used when performing communication between a base station and a mobile station according to such a communication method.

[0003]

2. Description of the Related Art Conventionally, when communication is performed between a base station and a mobile station in a mobile communication system using an adaptive array antenna, an antenna directivity pattern as shown in FIG. It is formed. That is, the antenna directivity pattern AP in the base station 101 installed at the roadside end of the road 105
Is a mobile device 103 (D) that is to communicate with the base station 101.
Is formed so that the peak of the antenna directivity pattern AP is directed in the direction of, and the null thereof is directed in the direction of the mobile station 104 (U) that communicates with another base station using the same channel. Then, the ratio of the maximum peak to null (D / U)
Is set to be 20 dB or more in consideration of short-term fluctuation and interruption of a direct wave.

[0004] By forming the antenna directivity pattern AP in the base station 101 as described above, even when the distances from the base station 101 to the respective mobile stations 103 and 104 are substantially equal, the distance from the mobile station 104 is reduced. Since the reception level of the interference wave at the base station 101 can be kept low,
Communication between the base station 101 and the mobile device 103 can be reliably performed. In addition, it is possible to prevent the radio wave radiated from the base station 101 to the mobile device 103 from affecting the mobile device 104 as an interference wave.

The above-described antenna directivity pattern AP
The receiving system of the base station 101 that performs the wireless communication with each mobile device by forming the above is configured, for example, as shown in FIG. This receiving system uses FDMA (Frequency
Division Multiple Access) is shown.

In FIG. 11, this receiving system has an array antenna unit 115 and a radio circuit unit 116. The array antenna unit 115 includes a plurality of antenna elements 106 constituting an array antenna and a down converter (DC
VT) 110. Wireless circuit unit 116
Are a plurality of antenna radiation pattern forming circuits 107, 107 'corresponding to each channel for processing in the baseband.
107 ''. This wireless circuit unit 116
Is further connected to each down converter (DCVT) 110 of the array antenna unit 115 by an information signal line and a frequency separation filter (FLT) 10 for channel separation.
9, 109 ′, 109 ″ and each frequency filter 10
Receiving circuits (Rv) 112, 112 ', 112''corresponding to respective channels connected to 9, 109', 109 ''
And Then, each receiving circuit (Rv) 112,
112 ′ and 112 ″ are connected to the corresponding antenna directivity pattern forming circuits 107, 107 ′ and 107 ″.

Further, the radio circuit unit 116 includes:
A local oscillation circuit 114 is provided, and an oscillation signal of a predetermined frequency is supplied from the local oscillation signal circuit 114 to each down converter 110 of the array antenna unit 115 via the local oscillation signal line. I have.

[0008] In the base station 101 having the receiving system configured as described above, the signal received by each antenna element 106 corresponds to the corresponding down converter (DCVT) 1.
10 and to the wireless circuit unit 115 via the information signal line. Then, in the wireless circuit unit 115, a signal from each antenna element 106 provided via each information signal line is converted into a frequency filter (FLT) 109,
At 9 'and 109'', the signals are separated for each channel and input to the corresponding receiving circuits (Rv) 112, 112' and 112 ''. And a receiving circuit (Rv) corresponding to each channel.
The signals 112, 112 ', and 112''are converted into baseband information signals.

Each receiving circuit (Rv) 112, 112 ', 1
The antenna directivity pattern forming circuits 107, 107 ', and 10' corresponding to the baseband information signal from 12 ''
7 ″ performs signal processing so as to realize reception in an antenna directivity pattern AP (see FIG. 10) that distinguishes an information signal for the mobile device 103 that performs communication from a signal that causes interference. Each antenna directivity pattern forming circuit 1
In the signal processing at 07, 107 ′, and 107 ″, the information signals corresponding to the signals from all the antenna elements 106 are weighted appropriately to combine the received signals. The weight to be applied to each of the above signals is the base station 103 with which communication is to be performed
Are determined in accordance with a predetermined algorithm so that the signal from the direction of the base station 104 is emphasized and the signal from the direction of the base station 104 that becomes an interference wave is attenuated.

[0010] The base station 101 also has a transmission system having a configuration substantially similar to that of the above-described reception system. The base station 101 forms the above-described antenna directivity pattern AP to transmit from the base station 101. The signal indicates that the mobile device 103 is to communicate.
, And is prevented from becoming an interference wave of the mobile station 104 communicating with another base station on the same channel.

[0011]

As described above, in a conventional communication method in which an antenna array directivity pattern is formed by an adaptive array antenna between a base station and a mobile station in a mobile communication system to perform wireless communication. Considering both directions of a mobile station communicating with a base station and a mobile station communicating with another base station using the same channel, baseband corresponding to signals received by all antenna elements is considered. The weight (directivity pattern) for the information signal must be determined. Therefore, the algorithm for determining the weight (directivity pattern) becomes complicated.

Also, the positional relationship between a mobile station that communicates with a base station and a mobile station that communicates with another base station using the same channel changes, or a mobile station that communicates with another base station uses the same channel. Each time the number of mobile devices performing communication increases or decreases, the antenna directivity pattern AP is changed. Therefore, high-speed performance is required for the antenna directivity pattern forming circuit corresponding to each channel.

[0013] Since processing at each antenna directivity pattern forming circuit performed according to a complicated algorithm as described above requires higher speed, it is difficult to realize each antenna directivity pattern forming circuit.

Further, each signal from the antenna elements must be processed in parallel until signals from all antenna elements are converted into baseband information signals.
Many hardware resources (information signal lines, frequency filters, receiving circuits, etc.) are required to realize the processing. Since such a large amount of hardware resources is required, the cost is increased, and it is also difficult to obtain a stable operation due to variations in the characteristics of the hardware resources.

Accordingly, a first object of the present invention is to provide a communication method which can easily realize radio communication between an access point and a mobile station by forming an antenna directivity pattern using an array antenna. That is.

A second object of the present invention is to provide a wireless communication device used when performing communication between a base station and a mobile device according to such a communication method.

[0017]

In order to solve the above-mentioned first problem, the present invention relates to a method for performing communication between a base station and a mobile station in a mobile communication system. A level having a single main beam and a plurality of side lobes extending in different directions from the main beam, and all side lobes do not substantially contribute to communication at the base station and communication at other mobile stations. It is configured to perform communication by forming an antenna directivity pattern.

In such a communication method in a mobile communication system, communication is performed between a base station and a mobile station by forming an antenna directivity pattern having a single main beam. Also, this antenna directivity pattern has a plurality of side lobes extending in a direction different from the main beam,
All the side lobes are at a level that does not substantially contribute to communication with the base station and communication with other mobile stations. Therefore, no matter where the other mobile station is located, the radio wave from the base station may affect the communication of the other mobile station as an interference wave, and the radio wave from the other mobile station may be transmitted to the base station. To the communication of the user as an interference wave is also suppressed.

According to the communication method as described above, the condition of the side lobe extending in a direction different from that of the main beam (a level substantially not contributing to communication at the base station and communication at another mobile station) is fixed. Therefore, the antenna directivity pattern is determined only by deciding the direction of a single main beam in consideration of the state of the transmission path between the base station and the mobile station without considering other mobile stations. be able to. For this reason, an antenna directivity pattern used for communication between the base station and the mobile device can be easily formed.

The level that does not substantially contribute to the communication at the base station and the communication at another mobile station, which is a condition of the side lobe, means that the radio wave transmitted from the base station by the side lobe communicates with another base station. This does not cause a substantial problem as an interference wave for other mobile stations that perform communication, and radio waves transmitted from other mobile stations that communicate with other base stations are implemented as interference waves for the base station. It does not matter.

From the viewpoint that the communication between the base station and the mobile station can always maintain a good communication state, the present invention as described in claim 2 provides the best communication quality in the above communication method. The antenna directivity pattern may be formed so that the main beam extends in the direction.

Even if the position of the mobile station communicating with the base station changes variously, the antenna directivity pattern used for communication between the base station and the mobile station can be formed more easily. According to a third aspect of the present invention, in the above communication method, a single main beam and a plurality of side lobes extending in different directions from the main beam are provided, and all the side lobes are connected to the base beam. Predetermine a plurality of antenna directivity patterns at a level that does not substantially contribute to communication at a station and communication at another mobile device, and select an antenna directivity pattern used for communication from the plurality of antenna directivity patterns. Can be configured.

In such a communication method, a directivity pattern used for communication between the base station and the mobile station can be formed by a selection process.

[0024] In view of facilitating diversity communication, the present invention provides, as set forth in claim 4,
In the above communication method, it is possible to form a configuration in which two or more predetermined antenna directivity patterns are formed, and diversity communication is performed using the predetermined number of antenna directivity patterns.

According to the communication method in such a mobile communication system, a predetermined number of side lobes having fixed conditions (a level substantially not contributing to communication at the base station and communication at another mobile station) are provided. Diversity communication is performed using the antenna directivity pattern. Therefore, an antenna directivity pattern used for diversity communication between the base station and the mobile device can be easily formed, and as a result, diversity communication can be easily performed.

In view of the fact that an antenna directivity pattern used for diversity communication between a base station and a mobile station can be more easily formed, the present invention provides the above-described communication system. The method has a single main beam and a plurality of side lobes extending in different directions from the main beam, and all side lobes do not substantially contribute to communication at the base station and at other mobile stations. A plurality of antenna directivity patterns serving as levels may be set in advance, and the predetermined number of antenna directivity patterns used for diversity communication may be selected from the plurality of antenna directivity patterns.

The condition of the side lobe of the antenna directivity pattern is a level that does not substantially contribute to communication at the base station and communication at another mobile station. As a result, the difference between the main beam of the antenna directivity pattern and all the side lobes is 20d.
It can be determined to be B or more.

The level of the side lobe depends on the size of the array antenna for forming the antenna directivity pattern. In view of forming an antenna directivity pattern with an array antenna of a realistic size, the present invention provides the communication method as described in claim 7, wherein the main beam and all side lobes are transmitted. Is preferably not more than 40 dB.

Further, from the viewpoint that it is possible to perform communication using various polarizations, the present invention provides, in each of the communication methods, a single main beam and a single main beam. An antenna directivity pattern having a plurality of side lobes can be shared by communication using radio waves of a plurality of types of polarization directions.

The radio waves in the plural kinds of polarization directions include, for example, horizontal polarization and vertical polarization or right-handed polarization and left-handed polarization.

In order to solve the above second problem, the present invention provides a wireless communication apparatus used when performing communication between a base station and a mobile station in a mobile communication system, as described in claim 9. An array antenna composed of a plurality of antenna elements, a single main beam and a plurality of side lobes extending in directions different from the main beam, and all side lobes communicate with the base station and perform other operations. An antenna directivity pattern forming means for forming an antenna directivity pattern at a level not practically contributing to communication at the mobile device in the array antenna, and an antenna directivity pattern forming means formed by the antenna directivity pattern forming means. And a communication unit that performs communication in the antenna directivity pattern.

[0032] Such a radio communication device can be applied to both a base station and a mobile station.

According to a tenth aspect of the present invention, in the wireless communication apparatus, the antenna directivity pattern forming means is arranged so that the main beam extends in a direction in which communication quality is best. It can be configured to form an antenna directivity pattern.

Further, according to the present invention, in each of the wireless communication devices, the antenna directivity pattern forming means includes a single main beam and a plurality of antennas extending in directions different from the main beam. And a multi-beam forming means for presetting a plurality of antenna directivity patterns having a level that does not substantially contribute to communication at the base station and communication at another mobile station having side lobes. And an antenna directivity pattern selecting means for selecting an antenna directivity pattern used for communication by the communication unit from a plurality of antenna directivity patterns set by the multi-beam forming means.

According to a twelfth aspect of the present invention, in the wireless communication apparatus, the multi-beam forming means includes a communication port corresponding to each of a plurality of antenna directivity patterns to be set. The directivity pattern selecting means has switch means for switching and selecting a tap connected to each communication port of the multi-beam forming means, and the communication unit is switched and selected by the switching means. It can be configured to communicate via a communication port connected to the tap.

According to a thirteenth aspect of the present invention, in the wireless communication apparatus, the antenna directivity pattern forming means may include two or more predetermined number of the antenna directivity. The communication unit may be configured to have a diversity communication unit that performs diversity communication using the predetermined number of antenna directivity patterns formed by the antenna directivity pattern forming means.

Further, according to the present invention, the antenna directivity pattern forming means has a single main beam and a plurality of side lobes extending in different directions from the main beam. A multi-beam forming means for setting a plurality of antenna directivity patterns at which all side lobes have a level that does not substantially contribute to communication at the base station and communication at another mobile device; and Antenna directivity pattern selecting means for selecting the predetermined number of antenna directivity patterns used for diversity communication by the diversity communication unit from the plurality of set antenna directivity patterns.

According to a fifteenth aspect of the present invention, in the wireless communication apparatus, the multi-beam forming means has a communication port corresponding to each of a plurality of directivity patterns to be set. The antenna directivity pattern selecting means includes switch means for switching and selecting any of the predetermined number of taps from taps connected to each communication port of the multi-beam forming means, and the diversity communication unit includes the switch The diversity communication can be performed via a communication port connected to the predetermined number of taps switched and selected by the means.

[0039]

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

An antenna directivity pattern AP formed by an adaptive array antenna according to the communication method according to one embodiment of the present invention is as shown in FIG. 1, for example. In this example, an antenna directivity pattern AP formed in a base station will be described. However, a similar antenna directivity pattern can be formed in a mobile device by a similar method.

In FIG. 1, a base station 1 is installed at the roadside end of a road 5 serving as a communication service area. A mobile station 3 (D) communicating with the base station 1 is located within the road 5.
(Hereinafter, referred to as a desired mobile station) and a mobile station 4 (U) (hereinafter, referred to as a mobile station) that communicates with another base station using the same channel used for communication between the base station 1 and the mobile station 3. , And interference mobile devices) are located at approximately the same distance from the base station 1.

In such a situation, the base station 1 has a single main beam M extending in the direction of the desired mobile station 3.
B and an antenna directivity pattern AP composed of side lobes SL extending in all other directions. Then, the intensity ratio of the main beam MB and the side lobe SL (D
/ U) is determined, for example, as follows.

In general, the short-term fluctuation of the reception level in an urban area is about 8 dB at a frequency of 3 GHz, and about 10 dB in a suburb, and the amount of reduction in the level when a person or an object blocks in the Fresnel zone is about 16 dB (" Radio Wave Propagation Handbook "Realize: Part 2 15
Chapter p. 202 and Part 2, Chapter 24, p. 368 1999
Published in January). Considering this, the main beam MB
If the intensity ratio between the main beam MB and the side lobe SL is equal to or more than 20 dB, the intensity of the main beam MB does not become smaller than the intensity of the side lobe SL due to the fluctuation of the reception level. If the intensity ratio between the main beam MB and the side lobe SL is 20 dB or more, the radio wave from the interfering mobile device 4 substantially acts as an interfering wave in the communication between the base station 1 and the desired mobile device 3. In addition to this, the radio wave from the base station 1 is also substantially prevented from acting as an interference wave in communication with the interfering mobile device 4.

In general, in an array antenna, the beam width (antenna gain) and the side lobe level are in a trade-off relationship, and the optimum antenna excitation distribution when any one is determined is a Chebyshev distribution (see “Entenna Engineering Handbook” Communication Society, pp.208-209
Ohmsha). Assuming this Chebyshev distribution, for example, when the beam width HP of the main beam MB is 4 °, the relationship between the level of the side lobe SL and the size of the antenna is expressed as follows.

[0045]

(Equation 1) Here, N is the number of antenna elements, d is the antenna element interval,
λ is the wavelength, L is the size of the antenna (see FIG. 2),
A is a constant for calculating the half power of the Chebyshev distribution array and depends on the side lobe level R (see FIG. 3).

The beam width HP of the main beam MB is set to 4
The magnitude L = {(N−1) d (λ)} when the side lobe level R is changed as ° changes as shown in FIG. Referring to FIG. 4, when forming the antenna directivity pattern AP such that the intensity of the side lobe SL is reduced by 20 dB from the intensity of the main beam MB, the size L (λ) of the antenna is determined by the intensity of the side lobe SL. There is not much difference compared to the case where it becomes larger. However, the intensity of the side lobe SL is 40 times smaller than that of the main beam MB.
When the dB decreases, the size L of the antenna (about 18λ) becomes
1. The size of an ordinary array antenna (about 12.5λ)
About 5 times. From this, the main beam M
The practical limit of the intensity ratio between B and the side lobe SL is about 40 dB.

As described above, the ratio between the intensity of the main beam MB and the intensity of the side lobe SL in the antenna directivity pattern AP (see FIG. 1) formed by the base station 1 is within the range of 20 dB and 40 dB. Preferably, it is set to a value.

It is preferable that the width HP of the main beam MB is as narrow as possible from the viewpoint of the influence from the interference mobile station and the transmission power. On the other hand, from the viewpoint of the followability of switching the direction of the main beam MB to the movement of the desired mobile station and the size (can be reduced) of the array antenna, the main beam MB
Is preferably as wide as possible. Therefore, the width HP of the main beam is determined based on the shape of the communication service area of the base station 1 in consideration of the above contradictory conditions.

Beam width H of main beam MB in horizontal plane
P is determined, for example, as shown in FIG. In the example shown in FIG. 5A, the distance along the road in the communication service area of the base station 1 is about 50 meters, and the road width is about 20 meters. In this case, the desired mobile station located at the point P farthest from the base station 1 has a range of about 1/4 of the road width in the road width direction (about 5 ° for an angle of about 20 ° where the point P is viewed from the base station 1). In order to ensure sufficient communication between the base station 1 and the desired mobile station (about 3 dB attenuation) while moving in the range (° range), the width of the main beam MB at the 3 dB attenuation position is set. HP is set to about 10 °.

The beam width HP of the main beam MB in the vertical direction is determined, for example, as shown in FIG. In the example shown in FIG. 5B, the height of the antenna of the base station 1 is 10 meters, and the distance along the road of the communication service area of the base station 1 is about 50 meters. In this case, the desired mobile station located at the point Q farthest from the base station 1 in the direction along the road has a range of about ２ along the road (about 10 degrees from the antenna of the base station 1 when viewing the point Q). (A range of about 5 ° with respect to °), the beam width in the vertical direction of the main beam MB in order to ensure sufficient communication between the base station 1 and the desired mobile station. HP is set to about 10 °.

As described above, the base station 1 is
And a side lobe LB extending in all other directions, and the intensity ratio between the main beam MB and the side lobe LB is always 20.
Since communication with the desired mobile station 3 is performed by forming an antenna directivity pattern AP of not less than dB, a sufficient reception signal level can be secured in the base station 1 and the desired mobile station 3. In addition, it is possible to suppress the transmission radio wave between the base station 1 and the desired mobile station 3 from acting as an interference wave on the interference mobile station 4, and the interference mobile station 4 communicates with another base station on the same channel. Can be suppressed from acting on the base station 1 as an interference wave.

In this case, the antenna directivity pattern AP is such that all side lobes SL have the main beam M
Since it is determined based on a single condition that it is lower than B by 20 dB or more, it may be formed by considering only the direction of the desired mobile station 3. That is, there is no need to consider the direction of the interference mobile device 4 when forming the antenna directivity pattern AP. Therefore, the algorithm for forming the above-described antenna directivity pattern AP is simplified, the processing time can be reduced, and the hardware for realizing it can be simplified.

The above-described antenna directivity pattern AP
The wireless communication device provided in the base station 1 that communicates with each mobile device by forming the above is configured, for example, as shown in FIG. FIG. 6 shows the reception system of the wireless communication device, but the transmission system can have substantially the same configuration. Communication between a base station and a mobile device using this wireless communication device is performed by an access method such as FDM.
A method is adopted.

In FIG. 6, the wireless communication device has an array antenna unit 35 and a wireless circuit unit 36. The array antenna unit 35 includes a plurality of antenna elements 16 configuring a multi-beam antenna set,
Multibeam forming circuit 17, R corresponding to communication channel
F switch 18, 18 ', 18'', each RF switch 1
It has band-pass frequency filters 19, 19 ', 19''connected to 8, 18', 18 '' and a down-converter circuit 20. In addition, the wireless circuit unit 36
Band bus frequency filter 2 corresponding to the communication channel
1, 21 ′, 21 ″, each bandpass frequency filter 2
Receiving circuits 22, 2 connected to 1, 21 ', 21''
2 ′, 22 ″, received signal determination circuits 23, 23 ′, 23 ″ connected to the respective reception circuits 22, 22 ′, 22 ″,
And a local oscillation circuit 24.

The multi-beam forming circuit 17 in the array antenna unit 35 includes a plurality of antenna elements 16
By appropriately controlling the weights (phases and amplitudes) of the antenna, a plurality of antennas each including a single main beam MB and a plurality of side lobes extending in different directions from the main beam MB as shown in FIG. Sex pattern A
P can be formed. Each of the antenna directivity patterns is configured such that adjacent main beams MB overlap each other when the level is lowered by 3 dB, and that the intensity ratio between each main beam MB and the side lobe SL with respect to each main beam MB is 20 dB or more. .

The multi-beam forming circuit 17 has a plurality of output ports, and receives from each of the output ports in an antenna directivity pattern formed by one main beam MB and its side lobe SL. The output signal is output. Therefore, by selecting this output port, an antenna directivity pattern composed of a single main beam MB and its side lobe SL contributing to communication with the mobile device is selected.

RF switch 1 corresponding to each communication channel
8, 18 ′ and 18 ″ are the multi-beam forming circuit 1
7 has taps corresponding to each output port, and each tap is connected to a corresponding output port of the multi-beam forming circuit 17. Each RF switch 18, 18 ',
The received signal selected at 18 ″ is input to the corresponding band-pass frequency filters 19, 19 ′, 19 ″, and the signal of the frequency band corresponding to each communication channel is input to each band-pass frequency filter 19, 19 ′, 19 ''. Each bandpass frequency filter 19, 19 ', 1
Signals in the frequency band corresponding to each communication channel from 9 ″ are combined into one signal and input to the down converter 20. The down converter 20 converts the input signal to a lower predetermined frequency and outputs the converted signal.

In the radio circuit unit 36, the signal input from the down converter 20 of the array antenna unit 35 via the signal line corresponds to each communication channel by each band-pass frequency filter 21, 21 ', 21''. It is separated into frequency band signals. Then, each of the separated signals corresponds to a corresponding one of the receiving circuits 22, 22 ',
The signal is demodulated by 22 ″ and converted into a baseband signal. The baseband signal output from each of the receiving circuits 22, 22 ', 22''is
3, 23 'and 23''. Each reception judgment circuit 2
3, 23 'and 23''determine the communication quality based on the input signal. Specifically, the communication quality is determined based on any one of a reception level, a desired wave-to-interference wave ratio, and a signal-to-noise ratio, or a combination thereof. Then, each of the reception signal determination circuits 23, 23 ′, 23 ″ transmits the determination result to the corresponding RF switch 18, 18 ′, 1 of the array antenna unit 35 via the control signal line.
It has returned to 8 ''. Each RF switch 18, 18 ',
18 ″ sequentially switches taps, and selects a tap that provides the best communication quality based on the communication quality determination result fed back from the wireless circuit unit 36 each time the tap is switched.

A signal of a predetermined frequency output from the local transmission circuit 24 of the radio circuit unit 36 is supplied to the down converter 20 of the array antenna unit 35 via a local transmission signal line. The down converter 20
Based on the signal from the local oscillation circuit 24, as described above, each band-pass frequency filter 19, 19 ', 1
The signal synthesized from the signal 9 ″ is converted (down-converted) into a predetermined frequency signal.

As described above, each RF switch 18, 1
When a tap that provides the best communication quality is selected in 8 ′ and 18 ″, wireless communication with the desired mobile station is performed in each communication channel in that state. Then, at that time, receiving circuits 23, 23 'corresponding to each communication channel,
The signal of each communication channel output from 23 ″ is supplied to a transmission unit (not shown) for the network via the corresponding reception signal determination circuit 23, 23 ′, 23 ″.

Communication is performed between the base station and the mobile device through various communication paths (multipath) due to the presence of the reflected wave. In consideration of such a situation, the above-described wireless communication apparatus sets the main beam MB to a path having the best communication quality.
The antenna directivity pattern is selected so as to correspond to. Therefore, it is possible to always maintain high quality communication between the base station and the desired mobile station.

The main beam MB and the side lobe SL attenuated by 20 dB or more with respect to the main beam MB
Are formed in advance, and one antenna directivity pattern is selected so as to obtain the best communication quality every time communication is performed with a desired mobile station. Therefore, only a switching process is required for forming a directivity pattern that contributes to actual communication, and the process can be performed at high speed.

The multi-beam forming circuit 17 does not need to change a plurality of (multi-beam) antenna directivity patterns AP set by changing or moving a desired mobile device for communication. On the other hand, high speed processing is not required particularly when a desired mobile device is changed or moved. Therefore, there is no difficulty in realizing the multi-beam circuit 17 due to the high-speed processing.

Further, since only an appropriate antenna directivity pattern is selected for each communication channel and a received signal in the selected directivity pattern is simply processed, as in the conventional apparatus (see FIG. 11). In addition, there is no need to process received signals from the antenna elements 16 in parallel for each communication channel. As a result, the hardware configuration of the wireless communication device can be simplified, cost can be reduced, and unstable operation due to variations in characteristics of hardware resources can be easily prevented. Can be.

As a result of simplifying the hardware configuration of the wireless communication apparatus, the number of signal lines connecting the array antenna unit 35 and the wireless circuit unit 36 can be further reduced. Usually, in a base station, the radio circuit unit 36 is installed in a station building, and the array antenna unit 35 is often installed in a high place such as a steel tower outside the station building. Considering such a situation, the wireless communication device capable of reducing the number of signal lines connecting the array antenna unit 35 and the wireless circuit unit 36 as described above has a problem in terms of signal loss and entry of disturbance. , Which is advantageous.

By the way, when a radio communication device having the above configuration communicates with a desired mobile station, if a radio wave from the desired mobile station comes between two overlapping main beams MB, the reception level of the main beam MB is optimized. 3d from reception level in case
B decreases. Also, the level of a signal received from the desired mobile station may decrease due to fading. Even in these cases, the function of diversity reception can be added to the above-described wireless communication device from the viewpoint of ensuring reliable communication.

In order to enable diversity reception in the wireless communication device, the RF switches 18, 18 ', 18''corresponding to each communication channel can be configured as shown in FIG. 8, for example.

In FIG. 8, each RF switch 18, 1
8 ′, 18 ″ include a first switch 181, a second switch 182, and a diversity combining circuit 183. First switch 181 and second switch 182
Each has a tap corresponding to each output port of the multi-beam forming circuit 17, and each tap is connected to a corresponding output port of the multi-beam forming circuit 17. The diversity combining circuit 183 generates a diversity received signal based on the received signal from the first switch 181 and the received signal from the second switch 182 according to a predetermined algorithm (optimum value selection, optimized combining, etc.).

When each of the RF switches 18, 18 ', 18''is configured as described above, each of the first switch 181 and the second switch 182 selects a tap having good communication quality. Thereby, two antenna directivity patterns having good reception quality are selected from a plurality of antenna directivity patterns AP as shown in FIG. Then, each signal received in each antenna directivity pattern (composed of the main beam MB and its side lobe SL) is transmitted from the corresponding output tap of the multi-beam forming circuit 17 via the first switch 181, The signals are also supplied to the diversity combining circuit 183 via the second switches 182. Then, the diversity reception signal generated from these signals is sent from the diversity combining circuit 183 to the subsequent band-pass frequency filter 19.
(19 ', 19'').

With the diversity reception as described above,
Even if the radio wave from the desired mobile station comes between the adjacent main beams MB, and even if it is affected by fading, the two main beams MB, such as those adjacent main beams MB, which are relatively good. For example, a signal to be optimized and synthesized is generated as a received signal from the received signal, so that the base station 1 can always perform good reception regardless of the position and environment of the desired mobile station.

The diversity synthesizing circuit 183
Are the bandpass frequency filters 19 (19 ′, 1 ′).
9 ''), but may be provided at the subsequent stage. Further, the circuit for realizing the diversity reception function is provided in the processing path of the RF signal, but may be provided in the processing path of the baseband signal.

Further, when the plurality of antenna elements 16 of the array antenna unit 35 constitute a multi-polarized beam multi-beam antenna set, the multi-beam forming circuit 17 is shared for receiving radio waves of vertically polarized waves and horizontally polarized waves. in this case,
Each of the main beams MB (multi-beam) in the plurality of antenna directivity patterns set by the multi-beam forming circuit 17 is, as shown in FIG.
And the reception of the horizontally polarized wave Hi. for that reason,
The output port of the multi-beam forming circuit 17 corresponding to each antenna directivity pattern is divided into an output port for vertical polarization and an output port for horizontal polarization. Therefore, the total number of output ports of the multi-beam forming circuit 17 is doubled. Even if the total number of output ports of the multi-beam forming circuit 17 doubles as described above, the above-described configuration can be achieved by using the RF switches 18, 18 ', and 18''having taps corresponding to the output ports. A wireless communication device can be configured with a similar configuration. In this case, the base station 1 can receive a signal from a mobile station that performs wireless communication using either a vertically polarized wave or a horizontally polarized wave.

In the above example, the vertical polarization and the horizontal polarization have been described. However, the radio communication apparatus can be similarly configured even when the communication of the right-handed polarization and the left-handed polarization is considered.

Although the above-mentioned radio communication apparatus employs the FDMA method as an access method, other access methods may be employed. Further, the wireless communication device can be provided on the mobile device side.

In each of the above examples, the multi-beam forming circuit 17 and each of the RF switches 18, 18 ', 18''correspond to antenna directivity pattern forming means. In particular, the multi-beam forming circuit 17 corresponds to the multi-beam forming means, and each of the RF switches 18, 18 ', 18''corresponds to the directivity pattern selecting means.

[0076]

As described above, according to the communication method according to the present invention as set forth in claims 1 to 8, communication between a base station and a mobile station can be performed without considering another mobile station. Since the antenna directivity pattern can be determined simply by determining the direction in which a single main beam faces in consideration of quality, the antenna directivity pattern used for communication between the base station and the mobile device can be easily formed. Will be able to As a result, wireless communication performed by forming an antenna directivity pattern between the base station and the mobile device using the array antenna can be easily realized.

Further, according to the present invention as set forth in claims 9 to 18, it is possible to realize a radio communication apparatus used when performing communication between a base station and a mobile station according to the above-described communication method. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an antenna directivity pattern used in a communication method according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship among an antenna element, a main beam, and a side lobe.

FIG. 3 is a diagram illustrating an example of a relationship between a side lobe level and a constant A;

FIG. 4 is a diagram illustrating an example of a relationship between an antenna size and a side lobe level.

FIG. 5 is a diagram illustrating an example of a state of formation of a main beam in the antenna directivity pattern illustrated in FIG. 1;

FIG. 6 is a block diagram illustrating a configuration of a wireless communication device according to an embodiment of the present invention.

7 is a diagram showing an example of an antenna directivity pattern set in the wireless communication device shown in FIG.

FIG. 8 is a block diagram illustrating a configuration example of a circuit that realizes a diversity reception function.

9 is a diagram showing another example of the antenna directivity pattern set in the wireless communication device shown in FIG.

FIG. 10 is a diagram showing an example of an antenna directivity pattern used in a conventional communication method.

FIG. 11 is a block diagram illustrating an example of a conventional wireless communication device.

[Explanation of symbols]

 Reference Signs List 1 base station 3 mobile station (desired mobile station) 4 mobile station (interfering mobile station) 5 road 16 antenna element 17 multi-beam forming circuit 18, 18 ', 18' 'RF switch 19, 19', 19 '' band pass frequency Filter 20 Downconverter 21, 21 ′, 21 ″ Bandpass frequency filter 22, 22 ′, 22 ″ Receiving circuit 23, 23 ′, 23 ″ Receiving signal judging circuit 35 Array antenna unit 36 Radio circuit unit 181 First Switch 182 second switch 183 diversity combining circuit

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5J021 AA05 AA06 CA06 DB02 DB03 DB04 EA04 FA14 FA15 FA16 FA17 FA20 FA31 FA32 GA02 GA08 HA05 HA06 HA10 5K059 CC04 DD37 5K067 AA23 CC24 EE02 EE10 KK02 KK03

Claims (18)

[Claims] When communication is performed between a base station and a mobile station in a mobile communication system, the mobile station has a single main beam, a plurality of side lobes extending in different directions from the main beam, and all side lobes are provided. A communication method in a mobile communication system configured to perform communication by forming an antenna directivity pattern at a level that does not substantially contribute to communication at the base station and communication at another mobile device. 2. The communication method according to claim 1, wherein said antenna directivity pattern is formed so that said main beam extends in a direction in which communication quality is best. 3. The communication method according to claim 1, comprising a single main beam and a plurality of side lobes extending in different directions from the main beam, wherein all side lobes communicate with the base station. Movement in which a plurality of antenna directivity patterns having a level that does not substantially contribute to communication with another mobile device are set in advance, and an antenna directivity pattern used for communication is selected from the plurality of antenna directivity patterns. A communication method in a communication system. 4. The communication method according to claim 1, wherein a predetermined number of two or more antenna directivity patterns are formed,
A communication method in a mobile communication system configured to perform diversity communication using the predetermined number of antenna directivity patterns. 5. The communication method according to claim 4, comprising a single main beam and a plurality of side lobes extending in directions different from the main beam, wherein all side lobes communicate with the base station and other side lobes. A plurality of antenna directivity patterns having a level that does not substantially contribute to communication in the mobile device are preset, and the predetermined number of antenna directivity patterns used for diversity communication are selected from the plurality of antenna directivity patterns. A communication method in a mobile communication system. 6. The communication method according to claim 1, wherein a difference between a main beam of the antenna directivity pattern and all side lobes is 20 dB or more. 7. The communication method according to claim 6, wherein a difference between said main beam and all side lobes is 40d.
B in a mobile communication system that does not exceed B. 8. The communication method according to claim 1, wherein an antenna directivity pattern having a single main beam and a plurality of side lobes is shared by communication using radio waves of a plurality of polarization directions. A communication method in a mobile communication system. 9. A wireless communication device used for performing communication between a base station and a mobile station in a mobile communication system, comprising: an array antenna including a plurality of antenna elements; The array has an antenna directivity pattern having a plurality of side lobes extending in different directions from the main beam, and having all side lobes at a level that does not substantially contribute to communication at the base station and communication at other mobile stations. A wireless communication device comprising: an antenna directivity pattern forming unit formed in an antenna; and a communication unit that performs communication using the antenna directivity pattern of the array antenna formed by the antenna directivity pattern forming unit. 10. The wireless communication apparatus according to claim 9, wherein said antenna directivity pattern forming means forms said antenna directivity pattern such that said main beam extends in a direction in which communication quality is best. Wireless communication device. 11. The radio communication apparatus according to claim 9, wherein said antenna directivity pattern forming means has a single main beam and a plurality of side lobes extending in different directions from said main beam. A multi-beam forming means for presetting a plurality of antenna directivity patterns at which side lobes have a level substantially not contributing to communication at the base station and communication at another mobile station; A radio communication apparatus comprising: an antenna directivity pattern selecting unit that selects an antenna directivity pattern used for communication by the communication unit from the plurality of antenna directivity patterns obtained. 12. The radio communication apparatus according to claim 11, wherein said multi-beam forming means has a communication port corresponding to each of a plurality of antenna directivity patterns to be set, and said directivity pattern selecting means, Switch means for selecting a tap connected to each communication port of the multi-beam forming means, wherein the communication unit communicates via a communication port connected to the tap selected and switched by the switch means A wireless communication device adapted to perform. 13. The radio communication apparatus according to claim 9, wherein said antenna directivity pattern forming means forms a predetermined number of said antenna directivity patterns of two or more, and said communication unit includes said antenna directivity pattern. A wireless communication device having a diversity communication unit that performs diversity communication using the predetermined number of antenna directivity patterns formed by the pattern forming means. 14. The radio communication apparatus according to claim 13, wherein said antenna directivity pattern forming means has a single main beam, a plurality of side lobes extending in directions different from said main beam, and all side lobes. Multi-beam forming means for setting a plurality of antenna directivity patterns at a level that does not substantially contribute to communication at the base station and communication at another mobile device; and a plurality of antennas set by the multi-beam forming means. An antenna directivity pattern selecting means for selecting said predetermined number of antenna directivity patterns used for diversity communication by said diversity communication hand unit from said antenna directivity pattern. 15. The radio communication apparatus according to claim 14, wherein said multi-beam forming means has communication ports respectively corresponding to a plurality of directivity patterns to be set, and said antenna directivity pattern selecting means comprises: Switch means for switching and selecting an arbitrary predetermined number of taps from taps connected to each communication port of the multi-beam forming means, wherein the diversity communication unit switches and selects the predetermined number of taps selected by the switch means Wireless communication device that performs diversity communication via a communication port connected to a tap of the wireless communication device. 16. The radio communication apparatus according to claim 9, wherein a difference between a main beam of the antenna directivity pattern and all side lobes is 20 dB or more. 17. The wireless communication apparatus according to claim 16, wherein a difference between said main beam and all side lobes is 40d.
A wireless communication device that does not exceed B. 18. The radio communication apparatus according to claim 9, wherein an antenna directivity pattern having a single main beam and a plurality of side lobes is transmitted by communication using a plurality of types of radio waves in polarization directions. A wireless communication device to be shared.