Multi-beam antenna system and wireless communication system

Abstract

This multi-beam antenna system is provided with: one transmitting DBF antenna unit (101) that is a transmitting antenna; a plurality of PAA units (103) that are transmitting antennas and are configured on the same plane on which the transmitting DBF antenna unit (101) is configured; and one receiving DBF antenna unit (102) that is a receiving antenna.

Description

Multi-beam Antenna System and Wireless Communication System

[0001] The technology described in this specification relates to a multi-beam antenna system and a wireless communication system.

[0002] Regarding the coverage of mobile phone operators in each country, although the population coverage rate is high, the area coverage rate may be low.

[0003] For example, regarding the coverage of mobile phone operators in Japan, although it depends on the operator and frequency, the population coverage rate is at most about 99%, but the area coverage rate is at most about 70%, and at least about 30% of the national land area is not covered.

[0004] Therefore, a wireless communication device capable of covering a wide range has been proposed by mounting a space division DBF (Digital Beam Forming) antenna on a satellite (for example, Non-Patent Document 3).

[0005] FIG. 1 is a diagram schematically showing a configuration example of a wireless communication system 600 in a conventional example.

[0006] The wireless communication system 600 includes a multi-beam antenna system 60 and USERS on the ground 2, airplanes, and HAPS (High Altitude Platform Station) not shown in the figure.

[0007] The multi-beam antenna system 60 includes one DBF Tx101 and one DBF Rx102 on the surface of the satellite body 3. Note that the satellite body 3 may be a HAPS.

[0008] The DBF Tx101 is a common transmission system for USERS on the ground 2, airplanes, and HAPS.

[0009] The DBF Rx102 is a common reception system for USERS on the ground 2, airplanes, and HAPS.

[0010] Space Cellular Study Task Group, "Document 43-1 Space Cellular Study Task Group Report," Ministry of Internal Affairs and Communications, Information and Communications Council, February 3, 2021. Kenji Suematsu, Tomoyuki Furuichi, Satoshi Tsukamoto, "Basic Study on Q / V Band Direct Digital RF DBF Transceiver Configuration for Satellite Mounting," IEICE Technical Report, end of July 2023. Kenji Suematsu, Tomoyuki Furuichi, Satoshi Tsukamoto, "Basic Study on Q / V Band DBF Antenna Device for LEO Constellation Satellite Mounting," IEICE Technical Report, vol. 123, no. 377, SAT2023-62, pp. 18-22, February 2024. Satoshi Suyama, Tatsuki Okuyama, Yuki Inoue, Yoshihisa Kishiyama, "5G Multi-Antenna Technology," NTT DOCOMO Tech. Journal vol.23(4), pp.30-39, 2016.

[0011] In conventional multi-beam antenna systems 60, it is possible to form many beams using DBF antennas, but there are limitations on the transmission power, and the bandwidth inevitably narrows as the number of beams increases.

[0012] In one aspect, the technology described herein aims to provide wireless communication devices that cover a wide range and broadband.

[0013] In one aspect, the multibeam antenna system comprises a single transmitting DBF (Digital Beam Forming) antenna unit which is a transmitting antenna, multiple PAA (Phased Array Antenna transmitter) units which are transmitting antennas and are configured on the same plane as the transmitting DBF antenna unit, and a single receiving DBF antenna unit which is a receiving antenna.

[0014] One aspect of this is that it can provide wireless communication devices that cover a wide area and broad bandwidth.

[0015] This figure schematically shows an example of the configuration of a wireless communication system in a conventional example. This figure schematically shows an example of the configuration of a wireless communication system in an embodiment. This is a block diagram schematically showing an example of the configuration of a communication device in an embodiment. This figure schematically shows an example of the configuration of the antenna module of the transmitting system shown in Figure 1. This figure schematically shows an example of the configuration of the antenna module of the receiving system shown in Figure 1. This is a block diagram schematically showing an example of the hardware configuration of the PAA Tx shown in Figure 2. This figure schematically shows an example of the arrangement of DBF Tx and PAA Tx on the ground-facing side of the satellite body shown in Figure 2.

[0016] The embodiments will now be described with reference to the drawings. However, the embodiments shown below are merely illustrative, and there is no intention to exclude various modifications or applications of techniques not explicitly shown in the embodiments. In other words, these embodiments can be implemented with various modifications without departing from their spirit.

[0017] Furthermore, each figure is not intended to represent only the components shown in the figure, but may include other components. In the following figures, parts denoted by the same reference numerals indicate the same or similar parts unless otherwise specified.

[0018] [A] Figure 2 of the embodiment is a schematic diagram showing an example of the configuration of the wireless communication system 100 in the embodiment.

[0019] The wireless communication system 100 includes a multibeam antenna system 10 and two ground users (not shown), an airplane, and HAPS.

[0020] The multibeam antenna system 10 comprises one DBF Tx101, a plurality (three in the example shown in Figure 2) PAA Tx103 (PAA Tx#1 to #3), and one DBF Rx102 on the surface of the satellite body 3. The satellite body 3 may be a HAPS. The DBF Tx101 may be called a transmitting antenna unit, the PAA Tx103 may be called a PAA unit, and the DBF Rx102 may be called a receiving DBF antenna unit.

[0021] DBF Tx101 corresponds to the transmitting antenna module 12b, which will be described later using Figures 3 and 4, and DBF Rx102 corresponds to the receiving antenna module 12a, which will be described later using Figures 3 and 5. An example of the hardware configuration of PAA Tx103 will be described later using Figure 6.

[0022] The DBF Tx101, DBF Rx102, and PAA Tx103 may all be equipped with the same number of antenna elements, and the transmission output of each antenna element may be equal.

[0023] Each PAA Tx103 transmits a single beam of broadband signal from multiple antennas to broadband communication targets such as airplanes, HAPS systems, and master stations. In the example shown in Figure 2, PAA Tx#1 transmits a beam to airplane #1, PAA Tx#2 transmits a beam to HAPS #1, and PAA Tx#3 transmits a beam to airplane #2. In other words, n (where n is a natural number) PAA units communicate with n broadband communication targets.

[0024] While PAA can only form one beam per surface, it allows for broader bandwidth compared to DBF. PAA can be used for beams targeting targets requiring broadband signals, such as HAPS, which are few in number.

[0025] The DBF Tx101 transmits multiple narrowband transmission signals from each of its multiple antennas to targets performing narrowband communication, such as USERs on the ground 2. In the example shown in Figure 2, the DBF Tx101 transmits beams to USERs #1 to #m on the ground 2. In other words, n (where n is a natural number) PAA units communicate with n targets performing broadband communication. In other words, m (where m is a natural number) transmitting DBF antenna units communicate with m targets performing narrowband communication. USERs may also be VSATs (small earth stations).

[0026] The DBF Rx102 is a common receiving system for ground-based USER 2, airplanes, and HAPS.

[0027] Figure 3 is a schematic block diagram showing an example of the configuration of the wireless communication device 1 in the embodiment.

[0028] The wireless communication device 1 corresponds to the combination of DBF Tx101 and DBF Rx102 shown in Figure 2, and is attached to an artificial satellite located at an altitude of 1000 km to communicate with a wireless communication terminal (not shown) on the ground 2, and comprises a receiving unit 1a and a transmitting unit 1b as shown in Figure 3. The wireless communication device 1 may, for example, cover the Q / V band, with DL (Down Link) at 40 GHz and UL (Up Link) at 50 Hz.

[0029] In Figure 3, only one receiving unit 1a and one transmitting unit 1b are shown, but the wireless communication device 1 may have multiple receiving units 1a and multiple transmitting units 1b.

[0030] The receiving unit 1a comprises a plurality of receiving antenna modules 12a and a DSP unit 13a. The transmitting unit 1b comprises a plurality of transmitting antenna modules 12b and a DSP unit 13b. Details of the transmitting antenna modules 12b will be described later with reference to Figure 4, and details of the receiving antenna modules 12a will be described later with reference to Figure 5. The transmitting DSP unit 13b and the receiving DSP unit 13a are disclosed, for example, in Non-Patent Document 3.

[0031] Figure 4 is a schematic diagram showing an example configuration of the antenna module 12b of the transmitting system shown in Figure 1.

[0032] In the example shown in Figure 4, the antenna module 12b consists of four elements corresponding to ANT#1 to #4, and includes a QSFP module 121, a DAC / CDR 122 (Digital-Analog Converter / Clock Data Recovery), a BPF 123, an amplifier 127, an SPDT-SW 124 (Single-Pole Double-Throw Switch), a PA 125 (Power Amplifier), a 90-degree HYB circuit 126, and a DBF antenna 11.

[0033] The QSFP module 121 converts the optical signal received from the DSP unit 13b via the optical fiber into an electrical signal. The DAC / CDR 122 converts the digital signal output by the QSFP module 121 into an analog signal and separates the clock and data. The BPF 123 is, for example, a spurious rejection filter, which removes aliasing spurious signals when converting the digital signal back to an analog signal. The amplifier 127 amplifies the signal in the bandwidth that has passed through the BPF 123. The SPDT-SW 124 inputs the input from the amplifier 127 to one of the two PAs 125 in the subsequent stage. The PA 125 amplifies the output signal from the SPDT-SW 124. 90 degrees. The HYB circuit 126 outputs a signal to the antenna 11 such that the two output signals have a phase difference of 90°. The DBF antenna 11 transmits the transmission beam.

[0034] Figure 5 is a schematic diagram showing an example configuration of the receiving system antenna module 12a shown in Figure 2.

[0035] In the example shown in Figure 5, the antenna module 12a consists of four elements corresponding to ANT#1 to #4, and includes a DBF antenna 11, a 90-degree HYB circuit 126, an LNA 128, an SPDT-SW 124, an amplifier 127, a BPF 123, an S / H (Sample / Hold) circuit 129, a 4-channel / 4Gbps ADC+P / S 130 (Analog Digital Converter + Parallel / Serial), and a 100GbE QSFP 121.

[0036] The DBF antenna 11 receives the received beam. The 90 deg. HYB circuit 126 eliminates the phase difference between two input signals having a 90° phase difference. The LNA (Low Noise Amplifier) 128 amplifies the input signal. The SPDT-SW 124 inputs the input from either of the two LNAs 128 to the subsequent amplifier 127. The BPF 123 is, for example, a spurious removal filter, and removes folding spurious when converting an analog signal back to a digital signal. The S / H circuit 129 discretizes (samples) the analog signal and keeps its voltage constant during the A / D conversion period. The ADC+P / S 130 converts a parallel analog signal into a serial digital signal. The QSFP module 121 converts an electrical signal into an optical signal and transmits it to the DSP unit 13a via an optical fiber.

[0037] FIG. 6 is a block diagram schematically showing a hardware configuration example of the PAA Tx103 shown in FIG. 2.

[0038] The PAA Tx103 includes one digital precoder 21, a plurality of IFFTs (Inverse Fast Fourier Transforms) 22, a plurality of +CP (Cycle Prefix) 23, a plurality of DACs 24, a plurality of upconverters 25, a plurality of variable phase shifters 26, and a plurality of antennas 27.

[0039] The digital precoder 21 pre-processes the signals of stream numbers #1 to #M according to the impulse response of the transmission line and inputs them to L IFFTs 22.

[0040] The IFFT 22 performs an inverse fast Fourier transform on the signal and converts it from the frequency domain to the time domain.

[0041] The +CP 23 mitigates the influence of signal interference due to multipath.

[0042] The DAC 24 converts a digital signal into an analog signal.

[0043] The upconverter 25 increases the frequency of the analog signal output from the DAC 24.

[0044] The variable phase shifter 26 shifts the phase of the input signal by a predetermined angle.

[0045] Antenna 27 (#1 to #N ,

[0051] , ,

[0050] ,

[0049] ) is targeted for broadband communication and transmits a broadband transmission signal.

[0046] FIG. 7 is a diagram schematically showing an arrangement example of the DBF Tx101 and the PAA Tx103 on the surface of the satellite body 3 shown in FIG. 2 facing the ground 2.

[0047] In the example shown in FIG. 7, a 256-element DBF antenna unit 101 for one surface is attached on the same plane of the satellite body 3, and four 256-element PAA units 103 are provided. In FIG. 7, although the illustration of the DBF antenna unit 102 for reception is omitted, the DBF antenna unit 102 for reception may be attached adjacent to, for example, the DBF antenna unit 101 for transmission.

[0048] For example, when the transmission band of one surface of the antenna unit is 80 MHz, the DBF antenna unit 101 can form 1 MHz band × 40 beams or 500 KHz band × 80 beams on one surface, and the PAA 103 unit can form 80 MHz band × 4 beams on four surfaces.

[0049] In the transmission system of the multi-beam antenna system 10, by arranging one DBF antenna unit 101 and a plurality of PAA units 103 on the same plane, a plurality of PAA units 103 can realize a small number of broadband beams (the number of beams equal to the number of PAAs), and one DBF antenna unit 101 can realize a large number of narrow-band beams.

[0050] The configuration of the antenna part can be simplified, and the cost can be reduced. Also, as for the DSP part, since there is one transmitter for one surface of the PAA and the DBF calculation is not required, compared with the case where the configuration shown in FIG. 7 is used for five surfaces of the DBF antenna, the calculation amount is approximately (256 + 4) / (256 × 4) ≒ 20%. Therefore, simplification of the device, cost reduction, and power consumption reduction are possible.

[0051] [B] The other disclosed technologies are not limited to the embodiments described above and can be implemented in various ways without departing from the spirit of each embodiment. Each configuration and each process of each embodiment can be selected or combined as needed.

[0052] 1: Wireless communication device 1a: Receiving unit 1b: Transmitting unit 11: DBF antenna 110: Basic unit 12a, 12b: Antenna module 121, 134: QSFP module 122: DAC / CDR 123: BPF 124: SPDT-SW 125: PA 126: 90 deg. HYB circuit 127: Amplifier 128: LNA 129: S / H circuit 130: ADC + P / S 13a, 13b: DSP section 100, 600: Wireless communication system 2: Ground 3: Satellite body 10, 60: Multibeam antenna system 101: DBF Tx (Transmitting DBF antenna unit) 102: DBF Rx (Receiving DBF antenna unit) 103: PAA Tx (PAA unit) 21: Digital precoder 22: IFFT 23: +CP 24: DAC 25: Upconverter 26: Variable phase shifter 27: Antenna

Claims

1. A multi-beam antenna system comprising: a single-sided transmitting DBF (Digital Beam Forming) antenna unit which is a transmitting antenna; multiple PAA (Phased Array Antenna Transmitter) units which are transmitting antennas and are configured on the same plane as the transmitting DBF antenna unit; and a single-sided receiving DBF antenna unit which is a receiving antenna.

2. The multibeam antenna system according to claim 1, wherein the number of antenna elements provided in the transmitting DBF antenna unit, the receiving DBF antenna unit, and the PAA unit are the same, and the transmission output of each antenna element is equal.

3. The multi-beam antenna system according to claim 1, wherein one beam of the broadband transmission signal is assigned to each of the PAA units, multiple beams of the narrowband transmission signal are assigned to the transmitting DBF antenna unit, and all of the receiving beams are assigned to the receiving DBF antenna unit.

4. A multi-beam antenna system for a wireless communication device that communicates with n (n is a natural number) targets performing broadband communication and m (m is a natural number) targets performing narrowband communication, wherein the transmitting antenna is composed of n PAA units and one DBF antenna unit, and the receiving antenna is composed of one DBF antenna unit.

5. A wireless communication system comprising: a multibeam antenna system according to claim 4, mounted on an artificial satellite; n targets for performing broadband communication, at least one of an aircraft, a HAPS (High Altitude Platform Station), and a ground base station; and m targets for performing narrowband communication, each consisting of a ground communication terminal and a VSAT (small earth station) device.

6. A multibeam antenna system comprising: a transmitting DBF antenna unit with one surface acting as a transmitting antenna; a transmitting PAA unit with one surface acting as a transmitting antenna and configured on the same plane as the transmitting DBF antenna unit; and a receiving DBF antenna unit with one surface acting as a receiving antenna, wherein the PAA unit transmits broadband communications to one ground base station, the transmitting DBF antenna unit transmits narrowband communications to m ground communication terminals, and the receiving DBF antenna unit communicates with all of the base station and communication terminals.

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