JP6452597B2 - Base station equipment - Google Patents

Description

  The present invention relates to a base station apparatus that performs wireless communication using a plurality of antennas.

  In a communication system that assumes that a base station and a mobile station traveling on a predetermined route, such as a train and an automobile, perform wireless communication, as described in Non-Patent Document 1, the mobile route It is preferable to install a base station having a directional antenna along the base station to form a base station antenna beam along the movement path. Thereby, a long and narrow cell along the moving path can be formed, and the cell length can be increased while suppressing interference with other systems.

Hiroshi Nishimoto et al., “Proposal of Millimeter-Wave Linear Cell for High-speed Mobiles”, IEICE General Conference, B-5-77, March 2015

  In the technique described in Non-Patent Document 1, a case where a base station is installed only on one side across a moving route is being studied. In the configuration described in Non-Patent Document 1, when a train or car that is a mobile station passes, radio waves are shielded by the vehicle body, and travels in a lane on the opposite side of the lane on which the base station is installed. The mobile station cannot receive radio waves from the base station, and communication may be interrupted.

  In order to solve this problem, a base station and a base station antenna may be installed on both sides of the moving path. However, in this case, the number of base stations and base station antennas is both doubled, which increases costs. Therefore, by installing only base station antennas on both sides of the movement path and transmitting the same signal from one base station from the base station antennas on both sides of the movement path, the increase in the number of base stations is suppressed. can do. However, in this case, when there is no passing of mobile stations and one mobile station can simultaneously receive radio waves from base station antennas on both sides of the mobile path, beat interference may occur depending on the position of the mobile station, resulting in poor communication quality. There is a risk.

  The present invention has been made in view of the above, and an object thereof is to obtain a base station apparatus capable of improving communication quality while suppressing an increase in cost.

  In order to solve the above-described problems and achieve the object, a base station apparatus according to the present invention uses a first signal and a second signal, which are two systems of transmission diversity coded signals having two branches. A signal generation unit that generates a transmission signal to be transmitted to a mobile station moving in a predetermined direction is provided. In addition, the base station apparatus is installed on both sides of the mobile station's mobile runway, and is installed on each side of the mobile station's mobile runway. Two second antennas for transmitting two signals. The two first antennas of the base station apparatus transmit the first signal with mutually orthogonal polarizations, the two second antennas transmit the second signal with mutually orthogonal polarizations, The polarization of the first antenna and the polarization of the second antenna installed on the same side are orthogonal to each other.

  According to the present invention, it is possible to realize a base station apparatus capable of improving communication quality while suppressing an increase in cost.

The figure which shows the structural example of the base station apparatus concerning Embodiment 1. 1 is a diagram illustrating a configuration example of a modulation device according to a first embodiment. 1 is a diagram illustrating an example of a processing circuit that implements a modulation device according to a first embodiment; The figure which shows the combination of the polarization allocation of the antenna concerning Embodiment 1 The figure which shows the example of antenna installation of the base station apparatus concerning Embodiment 1. The figure which shows the structural example of the base station apparatus concerning Embodiment 2. The figure which shows the antenna installation example of the base station apparatus concerning Embodiment 2.

  Below, the base station apparatus concerning embodiment of this invention is demonstrated in detail based on drawing. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of a base station apparatus according to the first embodiment of the present invention. The base station device 1 includes a modulation device 10 that is a signal generation unit and antennas 30-1 to 30-4. The antennas 30-1 to 30-4 are directional antennas and form a beam in a specific direction. The directivity of the antennas 30-1 to 30-4 is fixed. Modulator 10 and antennas 30-1 to 30-4 are connected via signal lines 20-1 to 20-4. The antennas 30-1 to 30-4 are installed on both sides of the mobile station runway 40, which is a mobile runway of a mobile station (not shown). It is assumed that the mobile station moves linearly on the mobile station runway 40 in both directions, that is, in the left-right direction indicated by the arrows shown in FIG. In practice, the base station apparatus 1 may include a demodulator for processing a signal received from the mobile station. However, in the following description, the function block on the receiving side is omitted because the function block on the receiving side is not referred to. The diagram is simplified. In addition, the mobile station includes at least one set of antennas whose polarizations are orthogonal.

  FIG. 2 is a diagram illustrating a configuration example of the modulation device 10. The modulation device 10 includes a modulation processing device 11, a DA (Digital to Analog) conversion device 12, and a frequency conversion device 13.

  In the modulation device 10, the modulation processing device 11 performs modulation processing on a transmission bit sequence input from the outside to generate a transmission signal. In the modulation processing executed by the modulation processing device 11, a space time block code (STBC), a differential space time block code (DSTBC), a space frequency block code (SFBC), Two systems of transmission signals, such as differential spatial frequency block code (DSFBC: Differential SFBC), which are two-branch transmission diversity coded with a coding rate of 1, that is, coding that realizes transmission diversity with two branches Two encoded transmission signals with a rate of 1 are generated. Here, any encoding scheme for realizing transmission diversity may be used. For example, an existing encoding scheme such as an Alamouti code can be used in the STBC scheme. The DA converter 12 performs DA conversion on the digital signals, which are the two transmission signals after the modulation processing, output from the modulation processor 11 and converts them into two analog signals. The frequency converter 13 frequency-converts the two analog signals output from the DA converter 12 into a carrier frequency signal. The DA converter 12 and the frequency converter 13 may be configured by an existing known technique.

  The modulation processing device 11 and the frequency conversion device 13 of the modulation device 10 can be realized by, for example, the processing circuit 100 shown in FIG. The processing circuit 100 includes an FPGA (Field Programmable Gate Array) 101 and its peripheral circuit 102. The DA converter 12 of the modulation device 10 can be realized by a DA converter.

  The signal line 20-M (M = 1 to 4) transmits the signal output from the frequency conversion device 13 of the modulation device 10 to the antenna 30-M. The signal line 20-M may be any medium as long as it is a wired cable that can transmit a signal, such as a coaxial cable or an optical fiber. The antenna 30-M transmits a signal input from the signal line 20-M by radio waves to a mobile station that is a communication partner. Here, in base station apparatus 1 of the present embodiment, antenna 30-1 and antenna 30-2 are a pair of antennas, antenna 30-3 and antenna 30-4 are a pair of antennas, and each antenna group is a mobile station. It is installed on both sides of the mobile station runway 40 across the runway 40, that is, at different ends in the direction orthogonal to the moving direction of the mobile station. The antenna set of the antenna 30-1 and the antenna 30-2 installed on the same side of the mobile station runway 40 may be two physically different antennas, or may be mounted on one casing like a polarization sharing antenna. It may be an antenna. Similarly, the antenna sets of the antenna 30-3 and the antenna 30-4 may be two physically different antennas, or may be an antenna mounted on one housing such as a polarization sharing antenna.

  The frequency conversion device 13 converts the analog signal input from the DA conversion device 12 into an intermediate frequency higher than the frequency of the signal input from the DA conversion device 12 and lower than the carrier frequency, and the antenna 30-M A configuration may be adopted in which an analog signal having an intermediate frequency is converted into a carrier frequency and then transmitted by radio waves. Alternatively, the DA converter 12 and the frequency converter 13 may be provided in the antenna 30-M instead of the modulator 10, and the signal line 20-M may be configured to transmit the digital signal generated by the modulation processor 11.

  Next, a transmission signal transmitted by the antenna 30-M will be described. In base station apparatus 1, modulation apparatus 10 outputs one of the two generated transmission signals to signal lines 20-1 and 20-3, and outputs the other to signal lines 20-2 and 20-4. That is, the first signal that is one of the two transmission signals generated by the modulation device 10 is input to the antennas 30-1 and 30-3 that are the first antennas, and the second signal that is the other is the first signal. The signals are input to antennas 30-2 and 30-4, which are two antennas. Accordingly, the same signals (one of the two systems of transmission signals) are transmitted from the antennas 30-1 and 30-3 that are the two first antennas, and the antennas 30-2 that are the two second antennas and 30-4 transmits the same signal (the other of the two transmission signals).

  Next, the polarization of the antenna 30-M will be described with reference to FIG. FIG. 4 is a diagram illustrating combinations of polarization assignments for each of the antennas 30-M. As shown in FIG. 4, the antenna 30-1 and the antenna 30-2 installed on the same side of the mobile station runway 40 use mutually orthogonal polarized waves. Similarly, the antenna 30-3 and the antenna 30-4 use polarized waves orthogonal to each other. Further, the antenna 30-1 and the antenna 30-4 have the same polarization, and the antenna 30-2 and the antenna 30-3 have the same polarization. For example, when the antennas 30-1 to 30-4 are linearly polarized antennas and the antenna 30-1 is vertically polarized, the antenna 30-2 is polarized horizontally and the antenna 30-3 is polarized. The waves are horizontally polarized waves, and the polarized waves of the antenna 30-4 are vertically polarized waves. This is the combination shown in the polarization allocation example 1 in FIG. As other combinations of the polarization assignment of the antenna 30-M, the combinations shown in the polarization assignment examples 2 to 4 in FIG. In the polarization allocation example 2, the antennas 30-1 and 30-4 have a combination of horizontal polarization and the antennas 30-2 and 30-3 have vertical polarization. Polarization allocation examples 3 and 4 are examples of polarization allocation when the antennas 30-1 to 30-4 are circularly polarized antennas. Polarization allocation example 3 is a combination of antennas 30-1 and 30-4 with right-handed polarization, and antennas 30-2 and 30-3 with left-handed polarization. The polarizations 30-1 and 30-4 are a left-handed polarization, and the antennas 30-2 and 30-3 are a right-handed polarization.

  Accordingly, the two transmission signals generated by the modulation device 10 are the transmission signal system 1 and the transmission signal system 2, respectively, and the polarizations of the antenna 30-1 and the antenna 30-4 are the polarization A, the antenna 30-2, and the antenna. Assuming that the polarization of 30-3 is the polarization B orthogonal to the polarization A, the transmission signal system 1 is the polarization A and the transmission signal system 2 is from the antenna set on one side with the mobile station runway 40 in between. Transmission is performed with polarization B, and transmission signal system 1 is transmitted with polarization B and transmission signal system 2 is transmitted with polarization A from the other antenna set. In this way, the transmission signal system 1 (first signal) is transmitted with polarized waves orthogonal to each other from the antennas 30-1 and 30-3 (first antenna) installed on both sides of the mobile station runway 40, The transmission signal system 2 (second signal) is transmitted with polarized waves orthogonal to each other from antennas 30-2 and 30-4 (second antenna) installed on both sides of the mobile station runway 40. Also, the two antennas installed on the same side of the mobile station device 40 transmit signals with mutually orthogonal polarizations. The mobile station (not shown) includes at least one set of antennas, one set of polarization A and one set of polarization B antennas. A signal superimposed with the signal system 2 is received.

  As described above, the base station apparatus 1 according to the present embodiment includes a modulation apparatus that generates two systems of transmission signals by two-branch transmission diversity encoding, and two polarization antennas whose polarizations are orthogonal to each other. The antenna set includes two antenna sets, and the two antenna sets are installed on both sides of the mobile station runway 40 which is the moving path of the mobile station. In addition, the base station apparatus 1 transmits two systems of transmission signals from each antenna set, and at this time, the same system of transmission signals is transmitted from the antennas on the left and right sides of the moving path with mutually orthogonal polarizations. . As a result, the mobile station does not pass each other and the mobile station and the antennas on the left and right sides of the movement path are in the line-of-sight environment, that is, when there is no other mobile station or other shielding object between the mobile station and each antenna. Increase in devices that can suppress beat interference and exclude signal lines 20-1 to 20-4 and antennas 30-1 to 30-4 that connect modulation device 10 and antennas 30-1 to 30-4 in base station device 1 The transmission diversity effect can be obtained while suppressing. Therefore, communication quality can be improved while suppressing an increase in the cost of the base station apparatus 1.

  Further, the antenna 30-M is a linearly polarized antenna, that is, the polarization of the antenna 30-M is a linearly polarized wave of the combination shown in the polarization allocation example 1 or 2 shown in FIG. You may install it inclining suitably. Specifically, each of the antennas 30-M may be installed in a state where it is inclined 45 degrees from a state in which the antennas 30-M are installed vertically, with the directivity direction of the antenna as a rotation axis. That is, the antenna 30-M may be installed so as to be inclined so that the plane of polarization of each radio wave radiated from each of the antennas 30-M is 45 degrees with respect to the horizontal plane. At this time, as shown in FIG. 5, the directions in which the antennas 30-M are inclined are all the same. Similarly, the antenna provided in the mobile station is also inclined by 45 degrees.

  In general, the amount of radio wave attenuation due to rainfall is greater for horizontally polarized waves than for vertically polarized waves. This is because the raindrops in the air are crushed in the horizontal direction. As shown in FIG. 5, when the vertically polarized antenna and the horizontally polarized antenna are inclined at 45 degrees in the same direction, the polarization plane of the radio wave radiated from each antenna is inclined 45 degrees with respect to the horizontal direction. It becomes a state and the effect which can eliminate the difference of the amount of electromagnetic wave attenuation by the polarized waves at the time of raining can be acquired collectively.

Embodiment 2. FIG.
FIG. 6 is a diagram of a configuration example of a base station apparatus according to the second embodiment of the present invention. The base station apparatus 1a is obtained by replacing the antennas 30-1 to 30-4 included in the base station apparatus 1 illustrated in FIG. 1 described in Embodiment 1 with antennas 30a-1 to 30a-4. In the present embodiment, parts different from those in the first embodiment will be described, and description of the same parts as those in the first embodiment will be omitted.

  The installation positions of the antennas 30a-1 to 30a-4 of the base station device 1a are the same as those of the antennas 30-1 to 30-4 of the base station device 1 according to the first embodiment. That is, the antenna 30a-1 and the antenna 30a-2 are a pair, and the antenna 30a-3 and the antenna 30a-4 are a pair. Each antenna pair sandwiches the mobile station runway 40 and is on both sides of the mobile station runway 40. Installed. The antennas 30a-1 and 30a-2 installed on the same side of the mobile station runway 40 may be two physically different antennas, or may be antennas mounted in one housing such as a polarization sharing antenna. . Similarly, the antennas 30a-3 and 30a-4 may be two physically different antennas, or may be antennas mounted in one housing such as a polarization shared antenna.

  The antennas 30a-1 and 30a-3, which are first antennas, transmit one of two transmission signals generated by the modulation device 10 by radio waves, and the antennas 30a-2 and 30a-, which are second antennas. 4 transmits the other of the two transmission signals generated by the modulation device 10 by radio waves. Here, the antenna 30a-1 and the antenna 30a-2 use polarized waves orthogonal to each other, and the antenna 30a-3 and the antenna 30a-4 use polarized waves orthogonal to each other. Also, when each of the antennas 30a-1 to 30a-4 has the same orientation, the antenna 30a-1 and the antenna 30a-3 have the same polarization, and the antenna 30a-2 and the antenna 30a-4 have the same polarization. To. However, the polarization used by the antennas 30a-1 to 30a-4 is limited to linear polarization. In the base station apparatus 1a according to the present embodiment, the antennas 30a-1 to 30a-4 are rotated with respect to the position where the radiated radio waves are vertically polarized waves or horizontally polarized waves. Install it at an angle of 45 degrees. That is, the antennas 30a-1 to 30a-4 are inclined and installed so that the polarization planes of the radio waves radiated from the antennas 30a-1 to 30a-4 are 45 degrees with respect to the horizontal plane. At this time, as shown in FIG. 7, the rotation direction, that is, the direction of tilting, of the set of the antenna 30a-1 and the antenna 30a-2 and the set of the antenna 30a-3 and the antenna 30a-4 are reversed. Specifically, in the case where the set of the antenna 30a-1 and the antenna 30a-2 is inclined by 45 degrees in the right direction (clockwise), the set of the antenna 30a-3 and the antenna 30a-4 is set in the left direction (counterclockwise). (Tilt) at 45 degrees. The direction in which each antenna is tilted may be reversed. Further, in the case where the set of the antenna 30a-1 and the antenna 30a-2 is tilted 45 degrees to the left, the set of the antenna 30a-3 and the antenna 30a-4 is tilted 45 degrees to the right.

  As shown in FIG. 7, by installing the antennas 30a-1 to 30a-4 at an angle, the plane of polarization of the radio wave radiated from the antenna 30a-1 and the plane of polarization of the radio wave radiated from the antenna 30a-3 are changed. The plane of polarization of the radio wave radiated from the antenna 30a-2 is orthogonal to the plane of polarization of the radio wave radiated from the antenna 30a-4.

  Thus, in the base station apparatus 1a according to the present embodiment, unlike the base station apparatus 1 according to the first embodiment, each of the transmission signal system 1 and the transmission signal system 2 that are two transmission signals is Transmission is performed with the same polarization from the linearly polarized antennas on the left and right sides of the moving path of the mobile station, and the polarization transmitting the transmission signal system 1 and the polarization transmitting the transmission signal system 2 are orthogonal to each other. The linearly polarized antennas on both the left and right sides of the moving path were installed at 45 degrees so that the rotation directions of the antennas on the left and right sides of the moving path were opposite directions with the directivity direction as the rotation axis.

  Even with the above configuration, it is possible to suppress beat interference when there is no passing of mobile stations and the mobile station and the base station antennas on the left and right sides of the moving path are in the line-of-sight environment, as in the first embodiment. The transmission diversity effect is suppressed while suppressing an increase in devices other than the signal lines 20-1 to 20-4 and the antennas 30a-1 to 30a-4 connecting the modulation device 10 and the antennas 30a-1 to 30a-4 in 1a. In addition, the difference in the amount of radio wave attenuation between the polarized waves during rainfall can be eliminated.

  As described above, the base station apparatus according to the present invention is useful for wireless communication that performs transmission diversity, and is particularly suitable for wireless communication with a mobile station that moves on a predetermined route.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1, 1a Base station apparatus, 10 modulation apparatus, 11 modulation processing apparatus, 12 DA conversion apparatus, 13 frequency conversion apparatus, 20-1 to 20-4 signal line, 30-1 to 30-4, 30a-1 to 30a- 4 antenna, 40 mobile station runway, 100 processing circuit, 101 FPGA, 102 peripheral circuit.

Claims (5)

A signal generation unit that generates a first signal and a second signal, which are two types of transmission diversity encoded signals having two branches, as transmission signals that are transmitted to a mobile station moving in a predetermined direction. When,
Two first antennas installed on both sides of the mobile runway of the mobile station and transmitting the first signal;
Two second antennas respectively installed on both sides of the mobile runway of the mobile station and transmitting the second signal;
With
The two first antennas transmit the first signal with mutually orthogonal polarizations;
The two second antennas transmit the second signal with mutually orthogonal polarizations;
The polarization of the first antenna and the polarization of the second antenna installed on the same side of the moving runway are orthogonal to each other,
A base station apparatus.   The base station apparatus according to claim 1, wherein the first antenna and the second antenna are linearly polarized antennas.   The base station apparatus according to claim 1, wherein the first antenna and the second antenna are circularly polarized antennas. The first antenna and the second antenna have directivity directions such that the polarization plane of each radio wave radiated from each of the first antenna and the second antenna is 45 degrees with respect to a horizontal plane. Installed in the same direction as the rotation axis,
The base station apparatus according to claim 2. A signal generation unit that generates a first signal and a second signal, which are two types of transmission diversity encoded signals having two branches, as transmission signals that are transmitted to a mobile station moving in a predetermined direction. When,
Two first antennas installed on both sides of the mobile runway of the mobile station and transmitting the first signal;
Two second antennas respectively installed on both sides of the mobile runway of the mobile station and transmitting the second signal;
With
The first antenna and the second antenna are linearly polarized antennas,
Each of the first antennas is installed in a different direction with the directivity direction as a rotation axis, and the respective polarized waves are orthogonal to each other ,
Each of the second antennas is installed in a different direction with the directivity direction as a rotation axis, and the respective polarizations are orthogonal to each other ,
The polarization of the first antenna and the polarization of the second antenna installed on the same side of the moving runway are orthogonal to each other,
The plane of polarization of each radio wave radiated from each of the first antenna and the second antenna has an inclination of 45 degrees with respect to a horizontal plane.
A base station apparatus.

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