Interference canceling by fixed division of feeder link transmission band in haps system having plural gateways
Abstract
Problem to be solved.To suppress interference in a multi-feeder link having the same frequency between an airborne communication relay device and a plurality of gateway (GW) stations.
Solution.A transmission signal band of a feeder link is divided into a plurality of divided frequency bands, and based on a reception result of a pilot signal received and separated from each of the plurality of GW stations, each of the plurality of GW stations and the communication relay device Multiple propagation path responses to the feeder link antenna of the above are estimated for each of the multiple division frequency bands with the central frequency of the division frequency band as the estimated frequency, and transmitted from the GW station based on the multiple propagation path responses. The weight for suppressing the interference signal that the transmitted signal is received by the directional beam corresponding to the remaining other GW stations and interferes is calculated for each divided frequency band, and corresponds to the GW station for each divided frequency band. From the received signal received by the directional beam, the received signal received by the directional beam corresponding to the other GW station is multiplied by the weight corresponding to the other GW station and subtracted. [Selection diagram] Fig. 22

Term
12.5 yearsto projected expiry
Projected expiry 27 March 2039, counted from filing; an application has no term until it is granted.
- Priority and filed
- Published
- Today
- Projected expiry
7 claims: 4 independent, 3 dependent
- 1端末装置の無線通信を中継する中継通信局を含む空中滞在型の通信中継装置を備えるシステムであって、 互いに時間同期され、前記空中滞在型の通信中継装置の前記中継通信局との間のフィーダリンクにおいて同一周波数で互いに異なる中継信号を送受信する複数のゲートウェイ局を備え、 前記中継通信局は、前記複数のゲートウェイ局との間のフィーダリンクにおいて同一周波数で互いに異なる中継信号を送受信するフィーダリンク通信部と、前記複数のゲートウェイ局との間に形成する複数のフィーダリンク間の干渉を抑圧する干渉抑圧部とを備え、 前記複数のゲートウェイ局はそれぞれパイロット信号を送信し、 前記フィーダリンク通信部は、前記複数のゲートウェイ局それぞれから送信されたパイロット信号を受信し、前記受信した複数のパイロット信号をそれぞれフィルターで分離し、 前記干渉抑圧部は、 前記フィーダリンクの送信信号帯域を複数の分割周波数帯に分割し、前記複数のゲートウェイ局それぞれから受信して分離した前記パイロット信号の受信結果に基づいて、前記複数のゲートウェイ局それぞれと前記通信中継装置のフィーダリンク用アンテナとの間の複数の伝搬路応答を、前記複数の分割周波数帯それぞれの中心周波数を推定周波数として、前記複数の分割周波数帯それぞれについて推定し、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局から送信した送信信号が他のゲートウェイ局に対応する指向性ビームで受信されて干渉する干渉信号を抑圧するためのウェイトを、前記複数の伝搬路応答に基づいて計算し、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局に対応する指向性ビームで受信した受信信号から、他のゲートウェイ局に対応する指向性ビームで受信した受信信号に前記他のゲートウェイ局に対応する前記ウェイトを掛けて減算する、ことを特徴とするシステム。
- 2請求項1のシステムにおいて、 前記複数の分割周波数帯は、前記フィーダリンクの送信信号帯域を等分割した周波数帯であることを特徴とするシステム。
- 3請求項1のシステムにおいて、 前記複数の分割周波数帯は、前記フィーダリンクの送信信号帯域における前記干渉信号の分布に応じて前記フィーダリンクの送信信号帯域を非等分割した周波数帯であることを特徴とするシステム。
- 4空中滞在型の通信中継装置に組み込まれ端末装置の無線通信を中継する中継通信局であって、 互いに時間同期された複数のゲートウェイ局との間のフィーダリンクにおいて同一周波数で互いに異なる中継信号を送受信するフィーダリンク通信部と、 前記複数のゲートウェイ局との間に形成する複数のフィーダリンク間の干渉を抑圧する干渉抑圧部と、を備え、 前記フィーダリンク通信部は、前記複数のゲートウェイ局それぞれから送信されたパイロット信号を受信し、前記受信した複数のパイロット信号をそれぞれフィルターで分離し、 前記干渉抑圧部は、 前記フィーダリンクの送信信号帯域を複数の分割周波数帯に分割し、前記複数のゲートウェイ局それぞれから受信して分離した前記パイロット信号の受信結果に基づいて、前記複数のゲートウェイ局それぞれと前記通信中継装置のフィーダリンク用アンテナとの間の複数の伝搬路応答を、前記複数の分割周波数帯それぞれの中心周波数を推定周波数として、前記複数の分割周波数帯それぞれについて推定し、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局から送信した送信信号が他のゲートウェイ局に対応する指向性ビームで受信されて干渉する干渉信号を抑圧するためのウェイトを、前記複数の伝搬路応答に基づいて計算し、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局に対応する指向性ビームで受信した受信信号から、他のゲートウェイ局に対応する指向性ビームで受信した受信信号に前記他のゲートウェイ局に対応する前記ウェイトを掛けて減算する、ことを特徴とする中継通信局。
- 5請求項4の中継通信局を有することを特徴とする空中滞在型の通信中継装置。
- 6空中滞在型の通信中継装置に組み込まれ端末装置の無線通信を中継する中継通信局におけるフィーダリンクの干渉抑圧方法であって、 互いに時間同期された複数のゲートウェイ局それぞれから送信されたパイロット信号を受信することと、 前記受信した複数のパイロット信号をそれぞれフィルターで分離することと、 前記フィーダリンクの送信信号帯域を複数の分割周波数帯に分割し、前記複数のゲートウェイ局それぞれから受信して分離した前記パイロット信号の受信結果に基づいて、前記複数のゲートウェイ局それぞれと前記通信中継装置のフィーダリンク用アンテナとの間の複数の伝搬路応答を、前記複数の分割周波数帯それぞれの中心周波数を推定周波数として、前記複数の分割周波数帯それぞれについて推定することと、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局から送信した送信信号が他のゲートウェイ局に対応する指向性ビームで受信されて干渉する干渉信号を抑圧するためのウェイトを、前記複数の伝搬路応答に基づいて計算することと、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局に対応する指向性ビームで受信した受信信号から、他のゲートウェイ局に対応する指向性ビームで受信した受信信号に前記他のゲートウェイ局に対応する前記ウェイトを掛けて減算することと、を含むことを特徴とする干渉抑圧方法。
- 7空中滞在型の通信中継装置に組み込まれ端末装置の無線通信を中継する中継通信局に設けられたコンピュータ又はプロセッサで実行されるプログラムであって、 互いに時間同期された複数のゲートウェイ局との間のフィーダリンクにおいて同一周波数で互いに異なる中継信号を送受信するためのプログラムコードと、 前記複数のゲートウェイ局それぞれから送信されたパイロット信号を受信するためのプログラムコードと、 前記受信した複数のパイロット信号をそれぞれフィルターで分離するプログラムコードと、 前記フィーダリンクの送信信号帯域を複数の分割周波数帯に分割し、前記複数のゲートウェイ局それぞれから受信して分離した前記パイロット信号の受信結果に基づいて、前記複数のゲートウェイ局それぞれと前記通信中継装置のフィーダリンク用アンテナとの間の複数の伝搬路応答を、前記複数の分割周波数帯それぞれの中心周波数を推定周波数として、前記複数の分割周波数帯それぞれについて推定するためのプログラムコードと、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局から送信した送信信号が他のゲートウェイ局に対応する指向性ビームで受信されて干渉する干渉信号を抑圧するためのウェイトを、前記複数の伝搬路応答に基づいて計算するためのプログラムコードと、 前記複数のゲートウェイ局それぞれについて、前記分割周波数帯ごとに、前記ゲートウェイ局に対応する指向性ビームで受信した受信信号から、他のゲートウェイ局に対応する指向性ビームで受信した受信信号に前記他のゲートウェイ局に対応する前記ウェイトを掛けて減算するためのプログラムコードと、を含むことを特徴とするプログラム。
Independent claims7
99 paragraphs, as filed
The present invention relates to interference canceling in a multi-feeder link of an airborne wireless relay device such as HAPS suitable for constructing a three-dimensional network.
Conventionally, communication relay devices such as high altitude platform stations (HAPS) (also referred to as "high altitude pseudo satellites") that can float and stay in the air are known (see, for example, Patent Document 1). The communication line in this airborne communication relay device is a feeder link between the communication relay device and the gateway (GW) station on the mobile communication network side, and a service link between the communication relay device and the terminal device. It is composed.
<p><patcit num="1"><text>U.S. Patent Application Publication No. 2016/0046387</text></patcit></p>
<p> Since the communication capacity of the service link of the above-mentioned levitation type communication relay device (hereinafter referred to as "air relay device") depends on the communication capacity of the feeder link which is the relay frequency, effective use of the frequency of the feeder link is indispensable. is there. Therefore, a method is conceivable in which a plurality of GW stations on the ground are installed at locations separated from each other to form a multi-feeder link that transmits and receives different feeder link signals at the same frequency from each GW station. However, unlike the fixed station, the sky relay device flies around in a predetermined airspace, so that dynamic interference may occur in the multi-feeder link of the same frequency between the sky relay device and a plurality of GW stations.</p>
<p> The system according to one aspect of the present invention is a system including an aerial stay type communication relay device including a relay communication station that relays the wireless communication of the terminal device. The system includes a plurality of gateway stations that are time-synchronized with each other and transmit and receive different relay signals at the same frequency on a feeder link with the relay communication station of the airborne communication relay device. The relay communication station is between a plurality of feeder links formed between a feeder link communication unit that transmits and receives different relay signals at the same frequency in a feeder link between the plurality of gateway stations and the plurality of gateway stations. It is provided with an interference suppression unit that suppresses the interference of the above. The plurality of gateway stations each transmit a pilot signal, the feeder link communication unit receives a pilot signal transmitted from each of the plurality of gateway stations, and the plurality of received pilot signals are separated by a filter. The interference suppression unit divides the transmission signal band of the feeder link into a plurality of divided frequency bands, and based on the reception result of the pilot signal received and separated from each of the plurality of gateway stations, the plurality of gateway stations. A plurality of propagation path responses between each and the feeder link antenna of the communication relay device are estimated for each of the plurality of divided frequency bands with the central frequency of each of the plurality of divided frequency bands as an estimated frequency, and the plurality of divided frequency bands are estimated. For each of the above-mentioned gateway stations, for each of the divided frequency bands, the plurality of weights for suppressing the interference signal in which the transmission signal transmitted from the gateway station is received by the directional beam corresponding to the other gateway station and interferes with each other are set. Calculated based on the propagation path response of the above, and for each of the plurality of gateway stations, the directionalness corresponding to the other gateway station is obtained from the received signal received by the directional beam corresponding to the gateway station for each divided frequency band. The received signal received by the beam is multiplied by the weight corresponding to the other gateway station and subtracted.</p><p> The relay communication station according to another aspect of the present invention is a relay communication station incorporated in an aerial stay type communication relay device and relaying wireless communication of the terminal device. The relay communication station is formed between a plurality of feeder link communication units that transmit and receive different relay signals at the same frequency in a feeder link between a plurality of gateway stations that are time-synchronized with each other, and the plurality of gateway stations. It is provided with an interference suppression unit that suppresses interference between the feeder links. The feeder link communication unit receives the pilot signals transmitted from each of the plurality of gateway stations, and separates the plurality of received pilot signals by filters. The interference suppression unit divides the transmission signal band of the feeder link into a plurality of divided frequency bands, and based on the reception result of the pilot signal received and separated from each of the plurality of gateway stations, the plurality of gateway stations. A plurality of propagation path responses between each and the feeder link antenna of the communication relay device are estimated for each of the plurality of divided frequency bands with the central frequency of each of the plurality of divided frequency bands as an estimated frequency, and the plurality of divided frequency bands are estimated. For each of the above-mentioned gateway stations, for each of the divided frequency bands, the plurality of weights for suppressing the interference signal in which the transmission signal transmitted from the gateway station is received by the directional beam corresponding to the other gateway station and interferes with each other are set. Calculated based on the propagation path response of the above, and for each of the plurality of gateway stations, the directionalness corresponding to the other gateway station is obtained from the received signal received by the directional beam corresponding to the gateway station for each divided frequency band. The received signal received by the beam is multiplied by the weight corresponding to the other gateway station and subtracted.</p><p> The aerial stay type communication relay device according to still another aspect of the present invention includes the relay communication station.</p><p> The interference suppression method according to still another aspect of the present invention is a feeder link interference suppression method in a relay communication station incorporated in an aerial stay type communication relay device and relaying wireless communication of the terminal device. The interference suppression method includes receiving pilot signals transmitted from each of a plurality of gateway stations time-synchronized with each other, and separating the received plurality of pilot signals with a filter. Further, the interference suppression method divides the transmission signal band of the feeder link into a plurality of divided frequency bands, and based on the reception result of the pilot signal received and separated from each of the plurality of gateway stations, the plurality of Estimate a plurality of propagation path responses between each of the gateway stations and the feeder link antenna of the communication relay device for each of the plurality of divided frequency bands, with the central frequency of each of the plurality of divided frequency bands as the estimated frequency. And, for each of the plurality of gateway stations, the weight for suppressing the interference signal in which the transmission signal transmitted from the gateway station is received by the directional beam corresponding to the other gateway station and interferes with each of the divided frequency bands. Is calculated based on the plurality of propagation path responses, and for each of the plurality of gateway stations, from the received signal received by the directional beam corresponding to the gateway station for each of the divided frequency bands, other gateways. It includes multiplying the received signal received by the directional beam corresponding to the station by the weight corresponding to the other gateway station and subtracting it.</p><p> The program according to still another aspect of the present invention is a program incorporated in an aerial stay type communication relay device and executed by a computer or a processor provided in a relay communication station that relays wireless communication of the terminal device. The program receives a program code for transmitting and receiving different relay signals at the same frequency on a feeder link between a plurality of gateway stations synchronized with each other, and a pilot signal transmitted from each of the plurality of gateway stations. A program code for separating the received pilot signals and a program code for separating the received plurality of pilot signals by a filter are included. Further, the program divides the transmission signal band of the feeder link into a plurality of divided frequency bands, and based on the reception result of the pilot signal received and separated from each of the plurality of gateway stations, the plurality of gateway stations. A program for estimating a plurality of propagation path responses between each of the communication relay devices and the feeder link antenna of the communication relay device for each of the plurality of divided frequency bands, with the central frequency of each of the plurality of divided frequency bands as the estimated frequency. For each of the code and the plurality of gateway stations, for each of the divided frequency bands, for suppressing an interference signal in which a transmission signal transmitted from the gateway station is received by a directional beam corresponding to another gateway station and interferes with each other. From the program code for calculating the weight based on the plurality of propagation path responses and the received signal received by the directional beam corresponding to the gateway station for each of the plurality of gateway stations for each divided frequency band. , A program code for multiplying and subtracting the received signal received by the directional beam corresponding to the other gateway station by the weight corresponding to the other gateway station.</p><p> In the system, the relay communication station, the aerial stay type communication relay device, the interference suppression method, and the program, the plurality of divided frequency bands are frequency bands obtained by equally dividing the transmission signal band of the feeder link. Alternatively, it may be a frequency band in which the transmission signal band of the feeder link is unequally divided according to the distribution of the interference signal in the transmission signal band of the feeder link.</p><p> In the system, the relay communication station, the airborne communication relay device, the interference suppression method, and the program, the pilot signals are plural, and the plurality of pilot signals are on both sides of the transmission signal band of the feeder link. It may be transmitted in a distributed manner in a plurality of guard bands located in.</p><p> In the system, the relay communication station, the airborne communication relay device, the interference suppression method, and the program, the plurality of weights are each a ZF (Zero-Forcing) method using the matrix of the propagation path response or the ZF (Zero-Forcing) method. It may be calculated by the MMSE (Minimum Mean Square Error) method.</p><p> In the system, the interference suppression method, and the program, the plurality of gateway stations may each include an antenna control unit that controls a feeder link antenna so as to track the aerial stay type communication relay device.</p><p> In the system, the airborne communication relay device, the interference suppression method, and the program, the airborne communication relay device is for a feeder link having a plurality of directional beams corresponding to each of the plurality of gateway stations. An antenna and an antenna control unit that controls the feeder link antenna so that the plurality of beams are directed toward the corresponding gateway stations may be provided.</p>
<p> According to the present invention, it is possible to suppress interference in a multi-feeder link having the same frequency between an airborne communication relay device and a plurality of gateway stations.</p>
<figref num="1">An explanatory diagram showing an example of a HAPS cell configuration in a communication system according to an embodiment of the present invention.</figref><figref num="2">(a) is a side view showing an example of a schematic configuration of a plurality of GW systems according to an embodiment. (b) is an explanatory diagram of the relationship between multiple feeder link antennas of HAPS and multiple GW stations as viewed from above.</figref><figref num="3">Explanatory drawing which shows an example of how the GW antenna of a plurality of GW stations according to an embodiment tracks HAPS.</figref><figref num="4">The explanatory view which shows an example of the directional beam of the plurality of FL antennas of HAPS which concerns on embodiment.</figref><figref num="5">The explanatory view which shows an example of the directional beam control of the FL antenna in HAPS which concerns on embodiment.</figref><figref num="6">The explanatory view which shows another example of the directional beam control of the FL antenna in HAPS which concerns on embodiment.</figref><figref num="7">The explanatory view which shows still another example of the directional beam control of the FL antenna in HAPS which concerns on embodiment.</figref><figref num="8">Explanatory drawing of an example of interference between GW stations (between feeder links) in a plurality of GW systems.</figref><figref num="9">Explanatory drawing which shows an example of the MIMO interference canceller which calculated and applied the weight W by the approximate expression.</figref><figref num="10">Explanatory drawing which shows an example of the schematic structure of the interference canceller part mounted on HAPS.</figref><figref num="11">Explanatory drawing which shows an example of the MIMO interference canceller applied by finding the weight W by the ZF method.</figref><figref num="12">Explanatory drawing which shows one reference example of the transmission signal band of a feeder link in a plurality of GW systems.</figref><figref num="13">The graph which shows an example of the result of the computer simulation which evaluated the interference reduction effect when the weight was calculated by the pilot frequency different from each other which concerns on a reference example.</figref><figref num="14">The graph which shows an example of the result of the computer simulation of the SINR characteristic of the whole transmission signal band of the feeder link when the body of HAPS is rotated.</figref><figref num="15">Explanatory drawing which shows one reference example of the frequency of each pilot signal when a plurality of GW stations each transmit a single pilot signal.</figref><figref num="16">The explanatory view which shows an example of the derivation model of the propagation path response of a feeder link using the pilot signal of FIG.</figref><figref num="17">Explanatory drawing which shows one reference example of the frequency arrangement of each pilot signal when a plurality of GW stations transmit a plurality of pilot signals each.</figref><figref num="18">The explanatory view which shows an example of the derivation model of the propagation path response of a feeder link using the pilot signal of FIG.</figref><figref num="19">Explanatory drawing which shows other reference example of arrangement of a pilot frequency when a plurality of GW stations transmit a plurality of pilot signals each.</figref><figref num="20">Explanatory drawing which shows still another reference example of arrangement of a pilot frequency when a plurality of GW stations transmit a plurality of pilot signals each.</figref><figref num="21">The graph which shows an example of the interference reduction effect when the weight was calculated based on the propagation path response estimated by the center frequency and the low frequency side end frequency of the transmission signal band FB of a feeder link as an estimated frequency.</figref><figref num="22">The explanatory view which shows an example of the frequency division and the interference amount reduction of the transmission signal band FB of a feeder link in the feeder link interference suppression processing which concerns on this embodiment.</figref><figref num="23">The graph which shows an example of the relationship between the number of divisions of a transmission signal band FB in the feeder link interference suppression processing which concerns on this embodiment, and SINR at the time of receiving a feeder link of HAPS.</figref><figref num="24">The explanatory view which shows another example of frequency division and interference amount reduction of the transmission signal band FB of a feeder link in the feeder link interference suppression processing which concerns on this embodiment.</figref><figref num="25">The explanatory view which shows an example of the main configuration of the relay communication station of HAPS which concerns on this embodiment.</figref>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a cell configuration of HAPS20 in the communication system according to the embodiment of the present invention. The communication system according to the present embodiment is suitable for realizing a three-dimensional network of fifth-generation mobile communication that supports simultaneous connection to a large number of terminal devices and low delay.
As shown in FIG. 1, the communication system is a high altitude platform station (HAPS) as a plurality of levitation type communication relay devices (wireless relay devices) (also referred to as "high altitude pseudo satellite" or "stratified area platform"). It has 20. HAPS20 is located in an airspace at a predetermined altitude and forms a three-dimensional cell (three-dimensional area) in the cell formation target airspace at a predetermined altitude. HAPS20 relays communication to an airship as a floating body that is controlled to float or fly in a high altitude airspace (floating airspace) of 100 [km] or less from the ground or sea surface by autonomous control or external control. The station 21 is installed.
The airspace in which HAPS20 is located is, for example, a stratospheric airspace with an altitude of 11 [km] or more and 50 [km] or less on the ground (or on the water such as the sea or lake). This airspace may be an airspace with an altitude of 15 [km] or more and 25 [km] or less in which the weather conditions are relatively stable, and in particular, an airspace with an altitude of approximately 20 [km].
The cell formation target airspace, which is the target airspace for forming a three-dimensional cell with one or more HAPS in the communication system of the present embodiment, is the airspace in which HAPS20 is located and a base station such as a conventional macrocell base station (for example, LTE). It is an airspace within a predetermined altitude range (for example, an altitude range of 50 [m] or more and 1000 [m] or less) located between the cell formation area near the ground covered by eNodeB).
The cell formation target airspace in which the three-dimensional cell of the present embodiment is formed may be above the sea, river, or lake. Further, the three-dimensional cell formed by HAPS20 may be formed so as to reach the ground or the sea surface so that it can communicate with the terminal device 61 located on the ground or the sea.
Each of the HAPS20 relay communication stations uses a service link antenna (hereinafter referred to as "SL antenna") 215 to form a plurality of beams for wireless communication with the terminal device 61, which is a mobile station, toward the ground. The terminal device 61 may be a communication terminal module incorporated in a drone, which is an aircraft such as a small helicopter that can be remotely controlled, or may be a user device used by a user in an airplane. Cell formation The area through which the beam passes in the target airspace is a three-dimensional cell. Multiple beams adjacent to each other in the cell formation target airspace may partially overlap.
The relay communication stations 21 of the HAPS 20 are, for example, a base station that wirelessly communicates with a gateway station (also referred to as a "feeder station") 70 as a relay station connected to a core network on the ground (or sea) side, or a ground station. It is a repeater slave unit that wirelessly communicates with the feeder station (repeater master unit) 70 as a relay station connected to the base station on the (or sea) side.
The relay communication station 21 of the HAPS 20 is connected to the core network of the mobile communication network 80 via the feeder station 70 installed on the ground or the sea where wireless communication is possible by the feeder link antenna (hereinafter referred to as "FL antenna") 211. Has been done. The feeder link communication between the HAPS 20 and the feeder station 70 may be performed by wireless communication using radio waves such as microwaves, or by optical communication using laser light or the like.
Each HAPS 20 may autonomously control its own levitation movement (flight) and processing at the relay communication station 21 by executing a control program by a control unit composed of a computer or the like incorporated therein. For example, each HAPS20 acquires its own current position information (for example, GPS position information), pre-stored position control information (for example, flight schedule information), position information of other HAPSs located in the vicinity, and the information thereof. The floating movement (flight) and the processing in the relay communication station 21 may be autonomously controlled based on the above.
In addition, the floating movement (flight) of each HAPS20 and the processing at the relay communication station 21 can be controlled by a management device (also referred to as a "remote control device") as a management device provided in a communication center of a mobile communication network. You may do so. The management device can be configured by, for example, a computer device such as a PC, a server, or the like. In this case, the HAPS20 incorporates a control communication terminal device (for example, a mobile communication module) so that it can receive control information from the management device and transmit various information such as monitoring information to the management device. Terminal identification information (for example, IP address, telephone number, etc.) may be assigned so that the information can be identified. The MAC address of the communication interface may be used to identify the control communication terminal device.
In addition, each HAPS20 is a management device that manages monitoring information such as information on the floating movement (flying) of HAPS in or around itself, processing by the relay communication station 21, information on the status of HAPS20, and observation data acquired by various sensors. It may be transmitted to a predetermined destination such as. The control information may include HAPS target flight route information. The monitoring information includes the current position of HAPS20, flight route history information, airspeed, ground speed and propulsion direction, wind speed and direction of airflow around HAPS20, and at least one information of air pressure and temperature around HAPS20. But it may be.
The uplink and downlink duplex schemes for wireless communication between the relay communication station 21 and the terminal device 61 are not limited to a specific scheme, and may be, for example, a Time Division Duplex (TDD) scheme. A Frequency Division Duplex (FDD) system may also be used. The access method for wireless communication between the relay communication station 21 and the terminal device 61 is not limited to a specific method, and is, for example, an FDMA (Frequency Division Multiple Access) method, a TDMA (Time Division Multiple Access) method, or a CDMA (Code). It may be a Division Multiple Access) method or an OFDMA (Orthogonal Frequency Division Multiple Access). In addition, the wireless communication includes diversity coding, transmission beamforming, and spatial division multiplexing (SDM). MIMO (Multi-Input and Multi-Output) technology that has functions such as Multiplexing) and can increase the transmission capacity per unit frequency by using multiple antennas for both transmission and reception at the same time. You may use it. Further, the MIMO technology may be SU-MIMO (Single-User MIMO) technology in which one base station transmits a plurality of signals at the same time and the same frequency as one terminal device, or one base station may have a plurality of signals. MU-MIMO (Multi-User MIMO) technology may be used in which signals are transmitted to different terminal devices at the same time and frequency, or a plurality of different base stations transmit signals to one terminal device at the same time and frequency. ..
In the following embodiment, the case where the communication relay device having the relay communication station 21 that wirelessly communicates with the terminal device 61 is the unmanned airship type HAPS 20 will be illustrated and described, but the communication relay device is a solar plane type HAPS. It may be. Further, the following embodiments can be similarly applied to other levitation type communication relay devices other than HAPS.
The link between HAPS 20 and the base station 90 via the gateway station (hereinafter abbreviated as "GW station") 70 as a feeder station is called "feeder link", and the link between HAPS 10 and terminal device 61 is called "feeder link". It is called "service link". In particular, the section between HAPS 20 and GW station 70 is called the "feeder link radio section". In addition, the downlink of communication from GW station 70 to terminal device 61 via HAPS 20 is called "forward link", and the uplink of communication from terminal device 61 to GW station 70 via HAPS 20 is "reverse link". Also called.
In FIG. 1, the communication relay device is an unmanned airship type HAPS20, but a solar-powered type HAPS may also be used. Further, in the illustrated example, HAPS20 is located in the stratosphere at an altitude of about 20 km, HAPS20 forms a plurality of cells 200C (1) to 200C (7), and the cells 200C (1) having a plurality of cells (7 cells) are configured. ) ~ 200C (7) footprint The service area 20A consisting of 200F (1) ~ 200F (7) has a diameter of 100 ~ 200km, but is not limited to these.
In FIG. 1, a communication service that directly communicates with a terrestrial (or water) terminal device 61 using HAPS20 located in the stratosphere is very attractive as a means of communication in the event of a disaster or expansion of a service area. The HAPS20 communication line consists of a feeder link FL that connects the GW station 70 and the HAPS20, and a service link SL that connects the HAPS20 and the terminal device 61. Since the communication capacity of the service link is determined by the communication capacity of the feeder link, which is the relay frequency, it is necessary to improve the frequency utilization efficiency of the feeder link. In particular, when the service link has a multi-cell configuration as shown in Fig. 9, the communication capacity of the feeder link tends to be insufficient, so the frequency effective utilization technology of the feeder link is indispensable. However, when the HAPS 20 and the GW station 70 are configured one-to-one, it is difficult to improve the frequency utilization efficiency of the feeder link.
Therefore, in the present embodiment, a plurality of GW stations that transmit and receive different relay signals at the same frequency in the feeder link with the HAPS 20 are provided, and the multi-feeder link formed between one HAPS 20 and the plurality of GW stations is provided. We are constructing a multiple gateway system (hereinafter also referred to as "multiple GW system") that performs spatial division multiplex communication. In this multiple GW system, by eliminating the interference between the plurality of feeder links, the frequency utilization efficiency can be improved by the number of installed GW stations.
In the following embodiment, a case where the time division multiplexing communication between the HAPS 20 and the plurality of GW stations is performed only by the forward link of the feeder link will be described, but the space division multiplexing communication is only the reverse link of the feeder link. It may be done with, or it may be done with both forward link and reverse link.
FIG. 2 (a) is a side view showing an example of a schematic configuration of a plurality of GW systems according to an embodiment, and FIG. 2 (b) shows a plurality of FL antennas 211 (1) to 211 (3) of HAPS 20 and a plurality of GWs. It is explanatory drawing which looked at the relationship with stations 70 (1) to 70 (3) from above. In the illustrated example, the number of FL antennas (N) and the number of GW stations (N) are the same (3 in the illustrated example), and the same number of FL antennas 211 (1) to 211 (3) and GW station 70 are used. (1) to 70 (3) are provided in a one-to-one correspondence with each other. Further, the number of sets of the FL antenna 211 and the GW station 70 may be two sets or four or more sets. Further, in the illustrated example, the plurality of GW stations 70 are arranged so that the distance from the HAPS 20 and the distance between the GW stations are equal to each other, but at least one of the distance and the distance may be different from each other. .. Each GW station 70 is arranged so that the complex amplitudes received by each FL antenna 211 (also referred to as "HAPS station antenna") of HAPS 20 are uncorrelated. In addition, the feeder link antennas of GW stations 70 (1) to 70 (3) (hereinafter referred to as "GW antennas") 71 (1) to 71 (3) are vertically polarized waves (V) and horizontally polarized waves that are orthogonal to each other. It can be transmitted and received with the two polarizations of (H). Further, in the illustrated example, the plurality of FL antennas 211 (1) to 211 (3) of the HAPS 20 are arranged so that the distance from the center of the HAPS 20 and the distance between the FL antennas are equal to each other. At least one of the intervals may be different from each other between the FL antennas. For example, the distance and the distance may be different from each other between the FL antennas.
Further, as shown in FIG. 3, each of the plurality of GW stations 70 (1) to 70 (3) controls the GW antennas 71 (1) to 71 (3) so as to track the HAPS 20 moving in the air. A control unit may be provided. The broken line HAPS20'in the figure indicates the position before the movement, and the solid line HAPS20 in the figure indicates the position after the movement. By tracking HAPS20 for each of GW antennas 71 (1) to 71 (3), even when GW antennas 71 (1) to 71 (3) with high directivity such as parabolic antennas are used, HAPS20 moves. It is possible to suppress the deterioration of the communication quality of the feeder link.
Further, as shown in FIG. 4, the plurality of FL antennas 211 (1) to 211 (3) of the HAPS 20 are antenna directional beams corresponding to the GW stations 70 (1) to 70 (3), respectively (hereinafter referred to as "directivity"). It has "beam" or "beam") 212 (1) to 212 (3), and HAPS20 has directional beams 212 (1) to 212 (3) of a plurality of FL antennas 211 (1) to 211 (3). ) May be provided with an antenna control unit that controls the FL antennas 211 (1) to 211 (3) so that they face the corresponding GW stations 70 (1) to 70 (3). The directional beams 212 (1) to 212 (3) of the FL antennas 211 (1) to 211 (3), for example, point in the direction of the GW station 70 that is most opposed to itself, and for the other GW stations, for example. It is formed so as not to cause interference, that is, the ratio (F / B) of the gain of the main beam to the gain in the opposite direction is sufficiently large. As a result, even when the HAPS 20 moves or rotates, it is possible to suppress a deterioration in the communication quality of the feeder link due to the movement and rotation of the HAPS 20.
The control method of the directional beams 212 (1) to 212 (3) of multiple FL antennas 211 (1) to 211 (3) by the antenna control unit of HAPS20 is the gimbal method and the electric method (360 degree beamforming control). Various methods such as (method) and electric method (beamforming control method with limited angle + antenna switching) can be used.
For example, in the gimbal method shown in FIG. 5, a plurality of FL antennas 211 (1) to 211 ( The entire 3) can be mechanically controlled by rotational drive. For example, in FIG. 5, when HAPS20 rotates about 45 degrees in the left rotation direction Rb, the entire FL antennas 211 (1) to 211 (3) mechanically move in the right rotation direction Ra opposite to the rotation direction. Rotate drive.
Rotational drive control for angle adjustment of each FL antenna 211 (1) to 211 (3) may be performed with reference to HAPS position and orientation information, but FL antennas 211 (1) to 211 (3) Rotational drive control of each FL antenna 211 (1) to 211 (3) may be performed with reference to the reception level value. For example, rotate each FL antenna 211 (1) to 211 (3) in small steps, find an angle that maximizes the reception level of each FL antenna 211 (1) to 211 (3), and turn to that angle. The rotation drive control of each FL antenna 211 (1) to 211 (3) is performed. Here, a threshold value is set for each reception level of each FL antenna 211 (1) to 211 (3), and when the value falls below that value, each FL antenna 211 (1) to 211 (3) is rotated by a predetermined angle. , The rotation drive control of the FL antennas 211 (1) to 211 (3) may be performed to the angle at which the reception level is maximized. The threshold value of the reception level may be obtained by an experiment in advance, and the default angle may be, for example, 360 degrees / the number of FL antennas (120 degrees in the illustrated example). Also, from FL antennas 211 (1) to 211 (3), create a monitoring beam to compare the reception level from other than the corresponding GW station, select the GW station with the maximum level, and select the directional beam in that direction. Each FL antenna 211 (1) to 211 (3) may be rotationally driven and controlled so as to face.
Although FIG. 5 shows the horizontal angle adjustment of each of the FL antennas 211 (1) to 211 (3), the vertical angle may be adjusted in the same manner.
Due to the rotation drive control of the FL antennas 211 (1) to 211 (3), the directional beams 212 (1) to 212 (3) of the FL antennas 211 (1) to 211 (3) can be generated even if the HAPS20 rotates. Since each direction is directed to the corresponding GW stations 70 (1) to 70 (3), deterioration of the communication quality of the feeder link can be prevented.
Further, in the electric system (360-degree beamforming control system) of FIG. 6, a circular array antenna 213 in which a plurality of antenna elements 213a are arranged along a circumferential shape is provided as an FL antenna. Then, based on the position and attitude information of HAPS20, the weight applied to the signal (amplitude, phase) transmitted and received via each of the plurality of antenna elements 213a is controlled. For example, the position and orientation information of HAPS20 is output to the output of the GNSS Inertial Navigation System (GNSS / INS), which is a combination of the GNSS (Global Navigation Satellite System) system incorporated in HAPS20 and the Inertial Measurement Unit (IMU). It may be obtained based on.
The weight of each antenna element 213a of the circular array antenna 213 may be controlled by referring to the HAPS position and orientation information, but the reception level value of each antenna element 213a of the circular array antenna 213 may be referred to. , The weight of each antenna element 213a may be controlled so as to form a directional beam having the maximum reception level at a position corresponding to each GW station. For example, the phase of each antenna element 213a of the circular array antenna 213 is changed in small steps to find an angle that maximizes the reception level, and the weight of each antenna element 213a is formed so that a beam is formed in that angle direction. Take control. Further, a monitoring beam for comparing reception levels from other than the corresponding GW station may be created from the circular array antenna 213, the GW station having the maximum level may be selected, and the beam may be formed in that direction.
Although FIG. 6 shows the beam angle adjustment in the horizontal direction, the beam angle adjustment may be performed in the vertical direction as well.
By controlling the weight of each antenna element 213a of the circular array antenna 213, directional beams 212 (1) to 212 (3) directed in the respective directions of the plurality of GW stations 70 (1) to 70 (3) are formed. As a result, even if the HAPS20 rotates, the directional beams 212 (1) to 212 (3) of the FL antennas 211 (1) to 211 (3) correspond to the corresponding GW stations 70 (1) to 70 (3), respectively. Since it faces in the direction, it is possible to prevent deterioration of the communication quality of the feeder link.
In the electric method shown in FIG. 7 (beamforming control method with limited angle + antenna switching), a plurality of planar array antennas 214 (1) to 214 (3) in which a plurality of antenna elements 214a are two-dimensionally arranged in a plane as FL antennas. To be equipped with. Then, based on the position and orientation information of HAPS20 acquired by GNSS / INS or the like, signals (amplitude) transmitted and received via each of the plurality of antenna elements 214a of the plurality of planar array antennas 214 (1) to 214 (3). , Phase), and beamforming control to control the weight applied to.
The switching of the planar array antennas 214 (1) to 214 (3) and the control of beamforming may be performed with reference to the information on the position and orientation of the HAPS, but the planar array antennas 214 (1) to 214 ( With reference to the reception level value of 3), antenna switching and beamforming may be controlled so that each of the planar array antennas 214 (1) to 214 (3) has the maximum reception level. For example, rotate each planar array antenna 214 (1) to 214 (3) in small steps, find an angle that maximizes the reception level of each planar array antenna 214 (1) to 214 (3), and use that angle. Each rotation drive control is performed so as to face. Here, a threshold is set for each reception level of each of the planar array antennas 214 (1) to 214 (3), and when the value falls below the threshold value, the planar array antennas 214 (1) to 214 (3) are switched. At the same time, each planar array antenna 214 (1) to 214 (3) may be rotated by a predetermined angle to perform beam forming to form a beam at an angle that maximizes the reception level. The threshold value of the reception level may be obtained by an experiment in advance, and the default angle may be, for example, 360 degrees / the number of FL antennas (120 degrees in the illustrated example). In addition, a monitoring beam is created from each planar array antenna 214 (1) to 214 (3) to compare the reception level from other than the corresponding GW station, and each planar array antenna 214 (1) to 214 (3) is the maximum. A GW station to be a level may be selected, and antenna switching and beamforming may be performed so as to form a beam in that direction.
Although FIG. 7 shows the beam angle adjustment in the horizontal direction, the beam angle adjustment may be performed in the vertical direction as well.
By switching the planar array antennas 214 (1) to 214 (3) and controlling the beamforming, the directional beams 212 (1) to 212 (3) directed in the respective directions of the plurality of GW stations 70 (1) to 70 (3). 3) is formed. Here, for example, the angle at which the directional beam 212 (1) is tilted with respect to the normal direction perpendicular to the plane of the plane array antenna 214 (1) (θ in the figure) is from a predetermined angle θth degree set in advance. When the size becomes large, the FL antenna corresponding to the GW station 70 (1) is switched to the planar array antenna 214 (2). As a result, even if the HAPS20 rotates, the directional beams 212 (1) to 212 (3) of the FL antennas 211 (1) to 211 (3) correspond to the corresponding GW stations 70 (1) to 70 (3), respectively. Since it faces in the direction, it is possible to prevent deterioration of the communication quality of the feeder link.
In a multiple GW system with the above configuration, interference between GW stations (between feeder links) may increase. For example, as shown in FIG. 8, when the desired signal (desired signal) S1 transmitted from the GW station 70 (1) is received by the FL antenna 211 (1) of the HAPS20, another GW station 70 (2). ), The signals transmitted from 70 (3) are received by the FL antenna 211 (1) as interference signals I2 and I3. Therefore, the SINR characteristics of the feeder link may deteriorate.
Therefore, in the present embodiment, as shown below, a MIMO interference canceller compatible with the line-of-sight environment (LOS: Line-Of-Sight) is applied between GW stations (between feeder links), and between GW stations (between feeder links). By reducing the interference, the SINR characteristics of the feeder link are improved.
FIG. 9 is an explanatory diagram showing an example of a MIMO interference canceller in which the weight W is obtained by an approximate expression and applied. FIG. 10 is an explanatory diagram showing an example of a schematic configuration of the interference canceller unit 220 mounted on the HAPS 20. The FL antenna 211 (1) of HAPS20 has the desired signal S1 (Y11) transmitted from the GW station 70 (1), the interference signal I2 (Y12) transmitted from the GW station 70 (2), and the GW station 70 ( Receives the interference signal I3 (Y13) transmitted from 3). The received signal AN1 is expressed by the following equation (1).<maths num="1"><img file="JP2020162002A_D0001.tif" /></maths>
In the interference canceller section 220 of HAPS20, as shown in the following equation (2), the signals S2 and S3 received by the other FL antennas 211 (2) and 211 (3) are multiplied by the corresponding weights W2 and W3 and subtracted. By doing so, the desired signal S1 (Y11) in which the interference signals I2 and I3 are canceled can be output. Similarly, the interference signals from other GW stations can be canceled for the desired signals S2 (Y22) and S3 (Y33) transmitted from the GW stations 70 (2) and 70 (3).<maths num="2"><img file="JP2020162002A_D0002.tif" /></maths>
FIG. 11 is an explanatory diagram showing an example of a MIMO interference canceller applied by obtaining a weight W by the ZF (Zero-Forcing) method. For example, the signal transmitted from the GW station 70 (1) is not only received as the desired signal S1 (Y11) by the FL antenna 211 (1) of the HAPS20, but also as the interference signals I1 (Y12) and I1'(Y13). Received by FL antennas 211 (2) and 211 (3). Further, the signal transmitted from the GW station 70 (2) is not only received by the FL antenna 211 (1) as an interference signal I2 (Y21), but also as an interference signal I2'(Y23) by the FL antenna 211 (3). Is received by. Further, the signal transmitted from the GW station 70 (3) is not only received by the FL antenna 211 (1) as an interference signal I3 (Y31), but also as an interference signal I3'(Y32) by the FL antenna 211 (2). Is received by. The MIMO interference canceller of FIG. 11 considers these interference signals I1, I1', I2'and I3', and outputs the desired signal S1 (Y11) as shown in the following equation (3), for example. As a result, the accuracy of interference suppression between GW stations (between feeder links) can be improved.<maths num="3"><img file="JP2020162002A_D0003.tif" /></maths>
In order to calculate the weight W used for the above MIMO interference canceller, it is necessary to grasp the propagation path response H between the FL antennas 211 (1) to 211 (3) of HAPS20. In particular, in the multiple GW system of the present embodiment, since the HAPS20 aircraft moves relative to the GW stations 70 (1) to 70 (3), the propagation path response also changes according to the movement.
Therefore, in the present embodiment, a pilot signal is transmitted from each GW station 70 (1) to 70 (3) in order to grasp the propagation path response. The frequency band of the pilot signal is a narrow band, and each pilot signal has a different transmission frequency (orthogonal). In the relay communication station 21 of HAPS20, for example, propagation of the center frequency fsc (see fsc in FIG. 12) of the transmission signal band FB of the feeder link is propagated based on the pilot signals received from each GW station 70 (1) to 70 (3). The road response is estimated and the weight W is derived.
The larger the difference between the frequency for which the weight W is obtained and the transmission signal band of the feeder link, the smaller the interference cancellation amount. For example, in the multiple GW system shown in Fig. 2 above, three GW stations 70 (1) to 70 (3) are installed at every 120 °, and the FL antennas 211 (1) to 211 (3) of the HAPS 20 relay communication station 21 are installed. ) Are installed every 120 ° on the circumference of radius Δd. Since the HAPS20 aircraft generally flies while rotating in the stratosphere, for example, as shown in FIG. 5 above, the FL antennas 211 (1) to 211 (3) of the relay communication station 21 are opposed to the GW station 70 (1) ~. Beam control is performed so that the main beam faces 70 (3). Here, the rotation angle Φ of the HAPS20 aircraft is a relative rotation angle with each GW station direction as 0 °. As the HAPS20 aircraft rotates, the propagation paths (mainly the phase due to the path length difference) of each FL antenna 211 (1) to 211 (3) on the circumference of the radius Δd change. Since the weight W is determined by the frequency of the pilot signal (hereinafter referred to as "pilot frequency"), the amount of interference cancellation in a signal band different from the pilot frequency decreases, and the larger the frequency difference, the smaller the amount of cancellation.
FIG. 13 is a graph showing an example of the results of computer simulation that evaluated the interference reduction effect when the weight W was obtained at different pilot frequencies. Further, FIG. 14 is a graph showing an example of the result of computer simulation of the SINR characteristics of the entire transmission signal band of the feeder link when the HAPS20 aircraft is rotated. The evaluation parameters are shown in Table 1.<tables num="1"><img file="JP2020162002A_D0004.tif" /></tables>
The radius Δd of the FL antenna (relay antenna) 211 is 0.5 [m], the gain of the FL antenna 211 is 20 [dBi], and the front-back ratio (F / B ratio) is 20 [dB]. Assuming that the reception SNR of the relay communication station 21 received by the omnidirectional antenna is 20 [dB], the reception SNR of the relay communication station 21 received by the FL antenna 211 is 40 [dB]. In addition, the transmission signal bandwidth of the feeder link is set to 18 [MHz]. As an example, the case where the pilot frequency is set at the edge and the center of the transmission signal bandwidth of the feeder link is evaluated.
As shown in FIG. 13, it can be seen that the amount of interference reduction in the transmission signal band of the feeder link differs depending on the pilot frequency. When the pilot frequency is set to the center of the transmission signal band (C2 in the figure), interference can be reduced over the entire transmission signal bandwidth. Further, as shown in FIG. 14, it can be seen that the SINR can be improved by 15 dB or more when the transmission signal band is set to the center (C2 in the figure) as compared with the case without the interference canceller.
FIG. 15 shows the frequency f of each pilot signal when the GW stations 70 (1) to 70 (3) each transmit a single pilot signal.<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>It is explanatory drawing which shows an example. FIG. 16 is an explanatory diagram showing an example of a derivation model of the propagation path response of the feeder link using the pilot signal of FIG. In the illustrated example, the pilot signal S from each GW station 70 (1) to 70 (3)<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>Are sent one by one. This pilot signal S<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>Is arranged in the first guard band GB1 which is the first adjacent band adjacent to the transmission signal band FB of the feeder link to which the desired signals S1, S2, S3 are transmitted from the low frequency side.
For example, the pilot signal h received by the FL antennas 211 (1) and 211 (2) of HAPS20.<sub>11</sub>, h<sub>21</sub>Are expressed by the following equations (4) and (5), respectively, and the ratio of their signals is expressed by the following equation (6).<maths num="4"><img file="JP2020162002A_D0005.tif" /></maths><maths num="5"><img file="JP2020162002A_D0006.tif" /></maths><maths num="6"><img file="JP2020162002A_D0007.tif" /></maths>
D in the above equations (4) to (6)<sub>1</sub>Is the path length between GW station 70 (1) and FL antenna 211 (1), Δd<sub>21</sub>Is the difference in path length (path difference) between the GW station 70 (1) and the FL antennas 211 (1) and 211 (2), respectively, and Δd<sub>31</sub>Is the difference in path length (path difference) between the GW station 70 (1) and the FL antennas 211 (1) and 211 (3), respectively. The path length between GW station 70 (1) and FL antenna 211 (2) is d<sub>1</sub>+ Δd<sub>21</sub>The path length between GW station 70 (1) and FL antenna 211 (3) is d.<sub>1</sub>+ Δd<sub>31</sub>It is represented by.
From the above equation (6), the above path difference Δd<sub>21</sub>Can be calculated by the following equation (7). Θ in the equation is h<sub>21</sub>And h<sub>11</sub>Is the phase difference with. The above path difference Δd<sub>31</sub>Other route differences such as, etc. can be obtained in the same manner.<maths num="7"><img file="JP2020162002A_D0008.tif" /></maths>
The above path difference Δd<sub>31</sub>And other path differences Δd<sub>12</sub>, Δd<sub>13</sub>, Δd<sub>23</sub>, Δd<sub>32</sub>Can be obtained in the same manner.
The above path difference Δd<sub>21</sub>, Δd<sub>31</sub>, Δd<sub>12</sub>, Δd<sub>13</sub>, Δd<sub>23</sub>, Δd<sub>32</sub>The propagation path response at the center frequency fsc of the transmission signal band of the feeder link can be estimated by the following equation (8).<maths num="8"><img file="JP2020162002A_D0009.tif" /></maths>
However, as shown in FIGS. 15 and 16, each of the GW stations 70 (1) to 70 (3) has one pilot signal S in the first guard band GB1.<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>When transmitting, the wavelength λ of each pilot signal<sub>1</sub>, Λ<sub>2</sub>, Λ<sub>3</sub>The above path difference cannot be detected. For example, the pilot signal S of GW station 70 (1)<sub>P1</sub>Frequency f<sub>1</sub>Is 3.3GHz, Δd<sub>21</sub>Is 0 <Δd<sub>21</sub>It can only be estimated in the range of <0.09 [m].
Therefore, in the present embodiment, each pilot signal S<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>Wavelength λ<sub>1</sub>, Λ<sub>2</sub>, Λ<sub>3</sub>In order to detect the above path difference, a plurality of pilot frequencies having different frequencies are transmitted from each of the GW stations 70 (1) to 70 (3). In the example of the following embodiment, the case where the GW stations 70 (1) to 70 (3) each transmit two or more pilot signals having different frequencies from each other is illustrated, but the GW station 70 (1) The number of pilot signals transmitted by each of ~ 70 (3) may be 3 or more. Further, the number of pilot signals may differ between GW stations 70 (1) to 70 (3).
FIG. 17 is an explanatory diagram showing an example of frequency arrangement of each pilot signal when a plurality of GW stations 70 (1) to 70 (3) each transmit a plurality of pilot signals. FIG. 18 is an explanatory diagram showing an example of a derivation model of the propagation path response of the feeder link using the pilot signal of FIG. In the illustrated example, the first adjacent band adjacent to the transmission signal band FB of the feeder link from which the desired signals S1, S2, S3 are transmitted from the GW stations 70 (1) to 70 (3) from the low frequency side and the high frequency side. A plurality of pilot signals transmitted from the respective GW stations 70 (1) to 70 (3) are distributed and arranged in each of the first guard band GB1 and the second guard band GB2 which are the second adjacent bands. Specifically, the frequencies f of each other transmitted from each GW station 70 (1) to 70 (3) to the first guard band GB1.<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>Different pilot signal S<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>Is located. In addition, the frequencies f of each other transmitted from each GW station 70 (1) to 70 (3) to the second guard band GB2.<sub>1</sub>', f<sub>2</sub>', f<sub>3</sub>'Different pilot signals S<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>'Is located. The HAPS20 relay communication station 21 has a plurality of pilot signals S of the first guard band GB1 received from the GW stations 70 (1), 70 (2) and 70 (3).<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>Are separated by filters, and multiple pilot signals S of the second guard band GB2 received from GW stations 70 (1), 70 (2) and 70 (3).<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>'Separate each with a filter.
For example, the pilot signal h received by the FL antennas 211 (1) and 211 (2) of HAPS20.<sub>11</sub>, h<sub>11</sub>', h<sub>21</sub>And h<sub>21</sub>'Is represented by the following equations (9), (10), (11) and (12), respectively, and the ratio / and / of their signals is expressed by the following equations (13) and (14), respectively.<maths num="9"><img file="JP2020162002A_D0010.tif" /></maths><maths num="10"><img file="JP2020162002A_D0011.tif" /></maths><maths num="11"><img file="JP2020162002A_D0012.tif" /></maths><maths num="12"><img file="JP2020162002A_D0013.tif" /></maths><maths num="13"><img file="JP2020162002A_D0014.tif" /></maths><maths num="14"><img file="JP2020162002A_D0015.tif" /></maths>
D in the above equations (9) to (14)<sub>1</sub>Is the path length between GW station 70 (1) and FL antenna 211 (1), Δd<sub>21</sub>Is the difference in path length (path difference) between the GW station 70 (1) and the FL antennas 211 (1) and 211 (2), respectively. The path length between GW station 70 (1) and FL antenna 211 (2) is d<sub>1</sub>+ Δd<sub>21</sub>It is represented by.
From the above equations (13) and (14), the above path difference Δd<sub>21</sub>Can be calculated by the following equation (15). Note that θ in Eq. (15) is h.<sub>11</sub>'And h<sub>11</sub>Phase difference and h<sub>21</sub>And h<sub>21</sub>It is the phase difference obtained by adding the phase difference of'. That is, θ = (h<sub>11</sub>'And h<sub>11</sub>Phase difference) + (h<sub>21</sub>And h<sub>21</sub>'Phase difference).<maths num="15"><img file="JP2020162002A_D0016.tif" /></maths>
Path difference between GW station 70 (1) and FL antennas 211 (1) and 211 (3) respectively Δd<sub>31</sub>And other path differences Δd<sub>12</sub>, Δd<sub>13</sub>, Δd<sub>23</sub>, Δd<sub>32</sub>Can be obtained in the same manner.
The above path difference Δd<sub>21</sub>, Δd<sub>31</sub>, Δd<sub>12</sub>, Δd<sub>13</sub>, Δd<sub>23</sub>, Δd<sub>32</sub>The propagation path response at the center frequency fsc of the transmission signal band of the feeder link can be estimated by using the above equation (8).
When the GW stations 70 (1) to 70 (3) each transmit a plurality of pilot signals as shown in FIGS. 17 and 18, the wavelength λ of each pilot signal is λ.<sub>1</sub>, Λ<sub>2</sub>, Λ<sub>3</sub>The above route difference can be detected. For example, assuming LTE, the bandwidth B of the feeder link transmission signal band FB is 18 MHz, so Δd as shown in the above equation (15).<sub>21</sub>Can be estimated within the wavelength range of the pilot frequency difference B. In this example, 0 <Δd, which is the range required for mounting.<sub>21</sub>It can be estimated accurately up to the range of <16 [m].
Further, in the examples of FIGS. 17 and 18, the frequencies f of each other transmitted from the respective GW stations 70 (1) to 70 (3).<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>, f<sub>1</sub>', f<sub>2</sub>', f<sub>3</sub>'Multiple pilot signals with different S<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>And pilot signal S<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>'Is distributed evenly in the first guard band GB1 and the second guard band GB2, so that each pilot signal can be separated by a filter and easily individually detected.
FIG. 19 is an explanatory diagram showing another example of arrangement of pilot signals when a plurality of GW stations 70 (1) to 70 (3) each transmit a plurality of pilot signals. In the illustrated example, the frequencies f of each other transmitted from the GW stations 70 (1) to 70 (3).<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>, f<sub>1</sub>', f<sub>2</sub>', f<sub>3</sub>'Multiple pilot signals with different S<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>And pilot signal S<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>This is an example in which all'are placed in the first guard band GB1. The HAPS20 relay communication station 21 has a plurality of pilot signals S of the first guard band GB1 received from the GW stations 70 (1) to 70 (3).<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>, S<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>'Separate each with a filter.
FIG. 20 is an explanatory diagram showing still another example of arrangement of pilot signals when a plurality of GW stations 70 (1) to 70 (3) each transmit a plurality of pilot signals. The illustrated example is an example in which the numbers of pilot signals arranged in the first guard band GB1 and the second guard band GB2 are different from each other. Specifically, the frequencies f of each other transmitted from the GW station 70 (1) to the first guard band GB1.<sub>1</sub>, f<sub>1</sub>'Different pilot signals S<sub>P1</sub>, S<sub>P1</sub>'Is located and the frequencies f of each other transmitted from GW stations 70 (2) and 70 (3) to the second guard band GB2.<sub>2</sub>, f<sub>2</sub>', f<sub>3</sub>, f<sub>3</sub>'Different pilot signals S<sub>P2</sub>, S<sub>P2</sub>', S<sub>P3</sub>, S<sub>P3</sub>'Is located. The relay communication station 21 of HAPS20 has a plurality of pilot signals S of the first guard band GB1 received from the GW station 70 (1).<sub>P1</sub>, S<sub>P1</sub>'Is separated by a filter, and multiple pilot signals S of the second guard band GB2 received from GW stations 70 (2) and 70 (3).<sub>P2</sub>, S<sub>P2</sub>', S<sub>P3</sub>, S<sub>P3</sub>'Separate each with a filter.
In particular, in the pilot signal arrangement example of FIG. 20, the pilot signals SPi, SPi'transmitted from each GW station 70 (i) (i = 1,2,3) are arranged in the same guard band. Specifically, the pilot signal S transmitted from the GW station 70 (1).<sub>P1</sub>, S<sub>P1</sub>'Is placed in the first guard band GB1 and the pilot signal S transmitted from GW stations 70 (2) and 70 (3)<sub>P2</sub>, S<sub>P2</sub>', S<sub>P2</sub>, S<sub>P3</sub>, S<sub>P3</sub>'Is located in the second guard band GB2. In this way, the frequency f from the same GW station 70 (i)<sub>1</sub>, f<sub>1</sub>'Pilot signal S transmitted by<sub>Pi</sub>, S<sub>Pi</sub>If you place'in the same guard band, f<sub>1</sub>-f<sub>1</sub>Since the frequency difference of'becomes small, Δd as shown in the above equation (15).<sub>21</sub>The estimated distance of is large.
The matrix H of the propagation path response<sub>fc</sub>The weight used for the interference canceller can be calculated by, for example, the ZF (Zero-Forcing) method or the MMSE (Minimum Mean Square Error) method using a matrix of propagation path responses.
For example, in the ZF method, the matrix H of the propagation path response is as shown in the following equation (16).<sub>fc</sub>The weight W can be obtained by the inverse matrix of.<maths num="16"><img file="JP2020162002A_D0017.tif" /></maths>
Further, in the MMSE method, the weight W can be used by the following equation (17). Where N<sub>T</sub>Is the number of transmitting antennas and γ is the SNR.<maths num="17"><img file="JP2020162002A_D0018.tif" /></maths>
In the examples of FIGS. 12 to 20 shown above, the propagation path response Hs (fi) at one estimated frequency fi in the transmission signal band FB is estimated from the pilot signal received from the GW station, and the propagation at the estimated frequency fi is estimated. The weight Wp is derived based on the road response Hs (fi). Ss'(a signal to be subtracted from the received signal from the target GW station) obtained by multiplying this wait Wp by the received signal Es from another GW station is calculated by, for example, the following equation (18). In the equation, Ss is a transmission signal transmitted from another GW station, N is noise, and Hs (fs) is a propagation path response at the transmission frequency fs of the transmission signal Ss in the transmission signal band FB.<maths num="18"><img file="JP2020162002A_D0019.tif" /></maths>
In the above equation (18), if the estimated frequency fi and the transmission frequency fs are equal (fi = fs), then (Hs (fi))<sup>-1</sup>Since Hs (fs)) Ss becomes the identity matrix I, the interference suppression amount (interference cancellation amount) is maximized, and the larger the difference (Δfi) between the estimated frequency fi and the transmission frequency fs, the interference suppression amount (interference cancellation amount). ) Decreases. For example, as shown in C1 of FIG. 21, when the estimated frequency fi from which the propagation path response Hs (fi) is estimated is located at the center frequency fsc of the transmission signal band FB of the feeder link, when the transmission frequency fs is the center frequency fsc. The interference suppression amount (interference cancellation amount) ΔIs is maximized, and as the transmission frequency fs approaches the end of the transmission signal band FB, Δfi increases, the interference suppression amount (interference cancellation amount) decreases, and Δfi at the terminal. Is the maximum and ΔIs is the minimum. Also, as shown in C2 of FIG. 21, when the estimated frequency fi from which the propagation path response Hs (fi) is estimated is located at the low frequency side end (fsc-B / 2) of the transmission signal band FB of the feeder link, Δfi is maximum, and when the transmission frequency fs is the low frequency side end (fsc-B / 2), the interference suppression amount (interference cancellation amount) is maximum, and the transmission frequency fs is the high frequency side end of the transmission signal band FB. As it approaches the part (fsc + B / 2), Δfi becomes larger and the interference suppression amount (interference cancellation amount) ΔIs decreases, and Δfi becomes maximum and ΔIs becomes minimum at the side end. When the transmission frequency fs is the center frequency fsc, the maximum value of Δfi is the minimum and the minimum value of ΔIs is the maximum, so that the interference reduction effect is the highest.
Therefore, in the present embodiment, in order to increase the interference suppression amount (interference cancellation amount) over the entire transmission signal band FB, the entire bandwidth B is set as shown in FIG. 22 and the following (1) to (3). The transmission signal band FB having is divided into a plurality of (n) frequency bands having a bandwidth B / n (hereinafter referred to as "divided frequency bands") FB1 to FBn, and the estimation of the propagation path response H and the weight W Interference suppression processing between feeder links including calculation is performed.
(1) Estimating the propagation path response for each divided frequency band: Multiple GW stations 70 (1) to 70 based on the reception results of pilot signals received from each of the multiple GW stations 70 (1) to 70 (3). (3) Multiple propagation path responses H (fsc1) to H (fscn) between each and the feeder link antennas 211 (1) to 211 (3) of HAPS20, and each of the multiple division frequency bands FB1 to FBn. The center frequencies fsc1 to fscn are used as the estimated frequency fi, and each of the plurality of divided frequency bands FB1 to FBn is estimated.
(2) Calculation of weight for each division frequency: For each of multiple GW stations 70 (1) to 70 (n), the transmission signal transmitted from the GW station is displayed for each n division frequency band (FB1 to FBn). The weights Wp1 to Wpn for suppressing the interference signal received and interfering with the directional beam corresponding to the other GW station are calculated based on the plurality of propagation path responses H (fsc1) to H (fscn).
(3) Interference cancel signal processing for each divided frequency: For each of multiple GW stations 70 (1) to 70 (3), a directional beam corresponding to the GW station is used for each of the n divided divided frequency bands FB1 to FBn. From the received received signal, the received signal received by the directional beam corresponding to the other GW station is multiplied by the weights Wp1 to Wpn corresponding to the other GW station and subtracted.
Here, assuming that the received signals in the plurality of divided frequency bands FB1 to FBn are Es1 to Esn, Ss'(the signal to be subtracted from the received signal from the target GW station) is calculated by, for example, the following equation (19). Ss in the formula is a transmission signal transmitted from another GW station, and N is noise. Hs (fsc1) to Hs (fscn) are propagation path responses estimated with the center frequencies fsc1 to fscn of the divided frequency bands FB1 to FBn as estimated frequencies, and Hs (fs1) to Hs (fsn) are divided frequencies, respectively. It is a propagation path response at the transmission frequency fs1 to fsn of the transmission signal Ss in the bands FB1 to FBn.<maths num="19"><img file="JP2020162002A_D0020.tif" /></maths>
By dividing the transmission signal band FB of the feeder link into a plurality of divided frequency bands FB1 to FBn and performing interference suppression processing between the feeder links including the estimation of the propagation path response H and the calculation of the weight W, FIG. 22 shows. As shown, the difference (Δfi) between the estimated frequency fi from which the propagation path response H is estimated and the transmission frequency fs of the feeder link becomes small, and the interference suppression amount (interference cancellation amount) ΔIs increases over the entire transmission signal band FB. be able to.
FIG. 23 is a graph showing an example of the relationship between the number of divisions (n) of the transmission signal band FB in the feeder link interference suppression processing according to the present embodiment and SINR [dB] at the time of receiving the feeder link of HAPS20. The vertical axis in the figure is the average value of SINR [dB] when HAPS20 makes one rotation (see FIGS. 5 to 7). As shown in FIG. 23, when the number of divisions (n) of the transmission signal band FB of the feeder link increases, the interference suppression effect between the feeder links is enhanced, and the communication quality (SINR) of the feeder link is improved.
In the example of FIG. 22, the transmission signal band FB of the feeder link is evenly divided, but the transmission signal band FB of the feeder link may be unequally divided. The unequal division of the transmission signal band FB may be performed according to the distribution of the interference signal of the feeder link in the transmission signal band FB of the feeder link. For example, as shown in FIG. 24, of the transmission signal band FB, only the band FB1 having a large or large interference signal of the feeder link is divided to enhance the interference suppression effect, and the remaining band FB2 having a small or small interference signal of the feeder link is It may not be divided.
FIG. 25 is an explanatory diagram showing an example of a main configuration of the relay communication station 21 of HAPS 20 according to the embodiment. In FIG. 25, the relay communication station 21 includes a feeder link communication unit 221, a service link communication unit 222, a frequency conversion unit 223, a control unit 224 that controls each unit, and an interference suppression unit 225.
The feeder link communication unit 221 transmits and receives a radio signal of the first frequency F1 for the feeder link to and from the GW station 70 via the FL antenna 211. Further, the feeder link communication unit 221 receives a plurality of pilot signals transmitted from each of the plurality of GW stations 70 (1) to 70 (3), and separates the received plurality of pilot signals by filters. The service link communication unit 222 transmits and receives a radio signal of the second frequency F2 for the service link to and from the terminal device 61 via the service link antenna 115. The frequency conversion unit 223 performs frequency conversion between the first frequency F1 and the second frequency F2 between the feeder link communication unit 221 and the service link communication unit 222. The radio signal relayed by the relay communication station 21 may be transmitted and received using, for example, an OFMDA communication method conforming to the LTE or LTE-Advanced standard. In this case, good communication quality can be maintained even if multipaths with different radio signal delays occur.
The control unit 224 can control each unit by executing a pre-installed program.
By executing a pre-installed program, the interference suppression unit 225 estimates the propagation path response for each of the above-mentioned (1) division frequency bands, (2) calculates the weight for each division frequency, and (3) for each division frequency. Interference cancel signal processing is performed.
When receiving control information from the remote control device (control source) of the communication operator of the mobile communication network or transmitting information to the remote control device, the user terminal (mobile station) connected to the control unit 224. It may be equipped with 226. For example, the control unit 224 may receive the control information transmitted from the remote control device at the user terminal (mobile station) 226 and control each unit based on the control information. Here, communication between the remote control device and the user terminal (mobile station) 226 is performed using, for example, the IP address (or telephone number) assigned to each of the remote control device and the user terminal (mobile station) 226. May be good.
As described above, according to the present embodiment, it is possible to suppress the interference in the multi-feeder link of the same frequency between the HAPS 20 and the plurality of GW stations 70 (1) to 70 (3).
In particular, according to the present embodiment, the transmission signal band FB of the feeder link is divided into a plurality of divided frequency bands, the propagation path response is estimated, the weight W is calculated, and the interference cancel signal using the weight W is used. By performing the processing, the minimum value of the interference suppression amount (interference cancellation amount) ΔIs in the entire transmission signal band FB can be lowered, and the interference suppression effect can be enhanced.
Further, according to the present embodiment, a plurality of pilot signals S having frequencies different from each other from each of the plurality of GW stations 70 (1) to 70 (3).<sub>P1</sub>, S<sub>P2</sub>, S<sub>P3</sub>, S<sub>P1</sub>', S<sub>P2</sub>', S<sub>P3</sub>By transmitting', the path difference between HAPS20 and multiple GW stations 70 (1) to 70 (3), which is required for dynamic suppression of interference in the multi-feeder link, is estimated to the range necessary for implementation. Since it can be grasped, it is possible to accurately suppress the interference in the multi-feeder link.
Further, according to the present embodiment, it is possible to improve the frequency utilization efficiency of the feeder link while suppressing the decrease in the SNIR of the feeder link of HAPS20.
The processing process described in this specification and the relay communication station, feeder station, gateway station, management device, monitoring device, remote control device, server, terminal device (user device, mobile station, etc.) of the communication relay device such as HAPS. The components of the communication terminal), the base station and the base station apparatus can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.
Regarding hardware implementation, the substance (for example, wireless relay station, feeder station, gateway station, base station, base station device, wireless relay station device, terminal device (user device, mobile station, communication terminal), management device, monitoring device) , A remote control device, a server, a hard disk drive device, or an optical disk drive device), the means such as a processing unit used to realize the above steps and components is one or more application-specific ICs (ASIC). , Digital Signal Processor (DSP), Digital Signal Processor (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), Processor, Controller, Microcontroller, microprocessor, Electronic Device, Book It may be implemented in other electronic units, computers, or combinations thereof designed to perform the functions described herein.
Also, for firmware and / or software implementation, means such as processing units used to implement the components are programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.) may be implemented. Generally, any computer / processor readable medium that clearly embodies the firmware and / or software code is a means such as a processing unit used to implement the steps and components described herein. May be used to implement. For example, the firmware and / or software code may be stored in memory and executed by a computer or processor, for example, in a control device. The memory may be implemented inside the computer or processor, or may be implemented outside the processor. Also, the firmware and / or software code may be, for example, random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable PROM (EEPROM). ), FLASH memory, floppy (registered trademark) discs, compact discs (CDs), digital versatile discs (DVDs), magnetic or optical data storage devices, etc. Good. The code may be executed by one or more computers or processors, or the computers or processors may be made to perform functional embodiments described herein.
Further, the medium may be a non-temporary recording medium. Further, the code of the program may be read and executed by a computer, a processor, or another device or device machine, and the format thereof is not limited to a specific format. For example, the code of the program may be any of source code, object code, and binary code, or may be a mixture of two or more of those codes.
Also, the description of the embodiments disclosed herein is provided to allow one of ordinary skill in the art to manufacture or use the disclosure. Various amendments to this disclosure will be readily apparent to those of skill in the art and the general principles defined herein are applicable to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be accepted in the broadest range consistent with the principles and novel features disclosed herein.
20 HAPS (Communication Relay Device) 21 Relay Communication Station 61 Terminal Device 70,70 (1) ~ 70 (3) Gateway Station (GW Station) 71,71 (1) ~ 71 (3) Feeder Link Antenna (GW Antenna) 200C, 200C (1) ~ 200C (7) 3D cell 200F, 200F (1) ~ 200F (7) Footprint 211, 211 (1) ~ 211 (3) Feeder link antenna (FL antenna) 212, 212 ( 1) ~ 212 (3) Antenna directional beam 215 Service link antenna (SL antenna)
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Every citation, both waysCites: the store holds 4 of 5
| Document | Relation | Office | Cited during |
|---|---|---|---|
| US2016046387A1 | Cites | United States of America | Search report |
| US2017126309A1 | Cites | United States of America | Search report |
| WO2018207612A1 | Cites | World Intellectual Property Organization (WIPO) | Search report |
| US9798329B2 | Cites | United States of America | Search report |
| 丸田 一輝 他: "マルチセルMassive MIMOシステムにおけるパイロット汚染除去のための干渉抑圧方式", 電子情報通信学会技術研究報告, vol. 118, no. 254, JPN6022048107, 11 October 2018 (2018-10-11), JP, pages 143 - 148, ISSN: 0004918482 | Non-patent | – | Search report |
| ISKANDAR ET AL.: "Interference analysis of border area technology: HAPS and GEO satellite in EXT-C band", 2017 3RD INTERNATIONAL CONFERENCE ON WIRELESS AND TELEMATICS (ICWT), JPN6022048108, 27 July 2017 (2017-07-27), pages 118 - 122, XP033317518, ISSN: 0004918483, DOI: 10.1109/ICWT.2017.8284151 | Non-patent | – | Search report |
| ALEXANDER HILARIO-TACURI ET AL.: "Probabilistic Model for the Interference Analysis from FWA-TDMA Systems Into HAPS", 2019 42ND INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING (TSP), JPN6022048109, 1 July 2019 (2019-07-01), pages 286 - 289, XP033579785, ISSN: 0004918484, DOI: 10.1109/TSP.2019.8769029 | Non-patent | – | Search report |
| 藤井 隆史 他: "HAPS マルチゲートウェイフィーダリンクシステムにおけるリバースリンク対応送信干渉キャンセラーの検討", 2019年通信ソサイエティ大会, vol. 通信講演論文集1, JPN6022048110, 27 August 2019 (2019-08-27), JP, pages 314, ISSN: 0004918485 | Non-patent | – | Search report |
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| 2019059852 | Japan | A | |
| JP20190059852 | – | – | – |
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| JP2020162002AThis record | Japan | A | |
| WO2020195294A1 | World Intellectual Property Organization (WIPO) | A1 | |
| EP3952147A1 | European Patent Office (EPO) | A1 | |
| US2022190907A1 | United States of America | A1 | |
| EP3952147A4 | European Patent Office (EPO) | A4 | |
| JP7184690B2 | Japan | B2 | |
| US11652537B2 | United States of America | B2 |
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Numbers
- Publication
- 2020162002
- Publication, DOCDB
- 2020162002
- Publication, EPODOC
- JP2020162002
- Application
- 59852
- Application, DOCDB
- 2019059852
- Application, EPODOC
- JP20190059852
Titles2
- Japanese
- 複数ゲートウェイHAPSシステムにおけるフィーダリンク送信帯域の固定分割による干渉キャンセリング
- English
- Interference canceling by fixed division of feeder link transmission band in multi-gateway HAPS system
Classification
- CPC, 7
- H04B7/18504
- H04B7/0413
- H04B7/0617
- H04B7/18513
- Y02D30/70
- H04B7/2041
- H04J1/10
- IPC, 6
- H04B7 185
- H04B7 026
- H04B7 0413
- H04B7 08
- H04J1 10
- H04W84 06