JP2019102978A - Transmission delay control of multi-sector cell in three-dimensional cell - Google Patents

Abstract

To suppress degradation of a reception level for whole of each sector cell and to suppress degradation of multi-pass resistance, when the same signal of a downlink is transmitted to all or a portion of a plurality of sector cells using a single frequency network (SFN) method by means of OFDM transmission.SOLUTION: A wireless apparatus, in which all or a portion of signals which are transmitted by means of OFDM transmission in a downlink of each of a plurality of sector cells constituting a wide area cell uses an SFN method being the same between the sector cells, forms a plurality of sector cells, transmits a signal through a wireless link to a terminal device being positioned at each sector cell, and controls a transmission timing of a downlink signal of each sector cell using a regular transmission pattern repeated in the plurality of sector cells such that transmission timings of the downlink signals of sector cells being adjacent to each other are not the same, and a transmission timing difference is minimized.SELECTED DRAWING: Figure 10

Description

  The present invention is a transmission delay between cells when transmitting a signal to a terminal device located in each of a plurality of sector cells forming a wide area cell formed by a base station of mobile communication, a wireless relay station, or a digital broadcast apparatus on the ground. It relates to control.

  Conventionally, a single frequency network (SFN) scheme is used in which all or part of signals transmitted by orthogonal frequency division multiplexing (OFDM) transmission in the downlink of each of a plurality of sector cells constituting a wide area cell are the same among sector cells Wireless devices are known. For example, in Non-Patent Documents 1 and 2, digital broadcast technology that performs delay diversity to give a fixed transmission timing difference between each sector cell when transmitting orthogonal frequency division multiplexing (OFDM) broadcast signals to a plurality of sector cells. Is disclosed. In this digital broadcasting technology, frequency selective fading occurs when transmitting the same signal, and it is considered that the reduction of the reception level can be suppressed over the entire sector cell including the sector cell boundary area such as LOS (Line of Sight) environment that can be viewed. ing.

S. Morosi, S. Jayousi and E. Del Re, "Cooperative Delay Diversity in Hybrid Satellite / Terrestrial DVB-SH System," 2010 IEEE International Conference on Communications, Cape Town, South Africa, 2010, pp. 1-5. Myung-Sun Baek, Yong-Hoon Lee, Namho Hur, Kyung-Seok Kim, and Yong-Tae Lee, "Improving the Reception Performance of Legacy T-DMB / DAB Receivers in a Single-Frequency Network with Delay Diversity," ETRI Journal , vol. 36, no. 2, Apr. 2014, pp. 188-196.

  However, when delay diversity is applied between sector cells by giving a transmission timing difference between sector cells as in the above-mentioned conventional digital broadcasting technology, the effective guard interval length at the time of transmission of an OFDM signal becomes short. Resistance may be reduced. Such a problem may also occur when a common signal common to each sector cell is transmitted as the same signal from a base station of mobile communication to a plurality of sector cells.

  A wireless device according to an aspect of the present invention is configured such that all or part of signals transmitted by orthogonal frequency division multiplexing (OFDM) transmission in downlink of each of a plurality of sector cells constituting a wide area cell is identical among sector cells. A wireless device using a single frequency network (SFN) scheme, wherein a transmission unit for transmitting signals to each of the plurality of sector cells and transmission timings of downlink signals of sector cells adjacent to each other are not identical And a controller configured to control the transmission timing of the downlink signal of each sector cell with a regular transmission pattern repeated in the plurality of sector cells so as to minimize the timing difference.

  In the wireless device, the control method of transmission timing of the downlink signal of each sector cell may be a delay diversity method in which transmission timing is controlled in each sector cell for the transmission signal on the time axis after inverse Fourier transform. . Here, the maximum value of the transmission timing difference between each sector cell of the downlink signal of each sector cell may be equal to or less than the cyclic prefix length.

  Further, in the wireless device, the control method of transmission timing of the downlink signal of each sector cell controls the phase of a subcarrier to which the signal is transmitted for all or part of the downlink signals of the plurality of sector cells. This may be a cyclic delay diversity (CDD) scheme in which the beginning of the signal is cyclically delayed in the OFDM symbol.

  Further, in the wireless device, the signal transmitted by the OFDM transmission is a common signal transmitted to each terminal device in order for a plurality of terminal devices located in the plurality of cells to connect to the wireless device. It is also good. Here, the signal transmitted by the OFDM transmission may be format indication information of downlink control information of PCFICH (Physical Control Format Indicator Channel), downlink data delivery confirmation information signal of PHICH (Physical HARQ Indicator Channel), PDCCH (Physical HARQ Indicator Channel). The downlink control information signal may include at least one of a downlink control information signal, a cell reference signal, a synchronization signal, and a system information signal.

  The wireless device may be a base station for mobile communication provided with the transmitting unit and the control unit, a wireless relay station that relays a signal transmitted and received by the base station, or a digital broadcast device. Further, the wireless device may include a base station of mobile communication provided with the control unit, and a wireless relay station provided with a front transmission unit and relaying a signal transmitted and received by the base station. Good. Also, the wireless device may be fixedly arranged on the ground or the sea, or may be incorporated in a mobile moving on the ground or the sea. The wireless relay station may be a repeater.

  In addition, the wireless device may be incorporated into a floating body or flying object located above the HAPS (High Altitude Platform Station) such as a balloon, a drone, a solar plane type or an airship type, an artificial satellite, etc. Good. Here, the wireless device may form a three-dimensional cell in a predetermined cell formation target airspace between the ground or the sea surface, and the height of the cell formation target airspace may be 10 [km] or less. The floating body or the flying body may be controlled to be located in an airspace of a predetermined height by autonomous control or external control. The floating body or the flying body may be a balloon, a drone, a HAPS (high altitude platform station) such as a solar plane type or an airship type, a satellite, or the like. Further, the floating body or the flying body may be located at an altitude of 100 [km] or less.

  Further, a communication system according to another aspect of the present invention includes a plurality of any one of the wireless devices.

  According to the present invention, when transmitting the same downlink signal by orthogonal frequency division multiplexing (OFDM) transmission to all or part of a plurality of sector cells using a single frequency network (SFN) scheme, It is possible to suppress the decrease in the reception level as a whole and to suppress the decrease in multipath resistance.

Explanatory drawing which shows an example of the sector cell which comprises the wide area cell formed centering on the base station which concerns on embodiment of this invention. The graph which shows an example of the directivity characteristic of the beam which forms each of two sectors of FIG. FIG. 3 is a graph showing an example of the directivity characteristic of FIG. 2 and a reception characteristic when the same signal is transmitted to each sector at the same timing. Explanatory drawing which shows an example of the transmission timing difference provided between the sectors in the base station of the 3 sector system of this embodiment. The graph which shows an example of improvement of the receiving characteristic when the transmission timing difference is provided between sectors. Explanatory drawing which shows an example of the 1st provision method (delay diversity system) of the transmission timing difference between 3 sectors. The explanatory view showing the other example of the 2nd grant method (cyclic delay diversity system) of the transmission timing difference between three sectors. Explanatory drawing which shows an example of the reception level fall inhibitory effect by the frequency selective fading in the transmission timing difference provision by a cyclic | annular delay diversity system. Explanatory drawing which shows one structural example of a resource block containing the signal * channel to which the transmission timing difference provision by a cyclic | annular delay diversity system is applied. Explanatory drawing which shows an example of the transmission timing difference provided between the sectors in the base station of 6 sector system of this embodiment. Explanatory drawing which shows an example of the transmission timing difference provided between the sectors in the base station of the 6 sector system of a comparative example. (A) And (b) is explanatory drawing which shows the example of provision of the transmission timing difference in case different signals are transmitted from each of several base stations in the mobile communication system of this embodiment. (A) And (b) is explanatory drawing which shows the example of provision of the transmission timing difference in case the same signal is transmitted from each of the several base station in the mobile communication system of this embodiment. Explanatory drawing which shows an example of a mode that a three-dimensional wide area cell is formed from each of several base stations arrange | positioned above the sky of this embodiment. FIG. 15 is an explanatory view showing an example of a transmission timing difference to be provided between a plurality of sector cells constituting the three-dimensional wide area cell of FIG. 14; FIG. 2 is a block diagram showing an example of the configuration of main parts of a base station according to the present embodiment. The block diagram which shows the structural example of the principal part of the radio | wireless apparatus which concerns on other embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an example of a cell (hereinafter referred to as a “wide area cell”) 100 formed centering on a base station 10 according to an embodiment of the present invention. The base station 10 as a radio apparatus of this embodiment forms a wide area cell 100 composed of a plurality of sector cells 101, 102, 103, and performs orthogonal frequency division multiplexing (OFDM) transmission in downlink of each of the sector cells 101, 102, 103. A single frequency network (SFN) scheme is used in which all or part of the transmitted signal is identical among the sector cells. In FIG. 1, a base station 10 is a terminal located in three sector cells (hereinafter referred to as "sectors" in the embodiment) 101, 102, and 103 formed of three beams having directivity in three different directions. Send a signal to the device 70. Sectors 101, 102, and 103 are communication service provision areas where transmission control can be individually performed by the base station 10.

  In the following embodiment, although the case of the base station 10 of mobile communication which transmits an orthogonal frequency division multiplexing (OFDM) signal will be described, the present invention forms a wide area cell including a plurality of sectors. The present invention can also be applied to a base station that transmits signals of a system other than OFDM, and to wireless devices other than the base station (for example, wireless repeaters such as repeaters, satellite digital broadcast devices, terrestrial digital broadcast devices, etc.). Further, the wide area cell and the sector forming the same may be formed two-dimensionally on the ground or the sea, or may be formed three-dimensionally in the space above the ground or the sea. Further, the number of sectors constituting the wide area cell may be two or four or more.

  Further, the terminal device 70 may be a mobile station as a user device such as a mobile phone or a smartphone of mobile communication, or may be a modular mobile station incorporated in a mobile object such as a car or a drone. . The terminal device 70 may be a terminal device of a device for IoT (Internet of Things).

FIG. 1 is a top view of a wide area cell 100 formed around a base station 10. The base station 10 forms three sectors 101, 102, and 103 with three beams having directivity centers in directions B1, B2, and B3 separated by 120 ° from each other. The angle φ _dir [°] of directivity central directions B1, B2 and B3 of each beam is an angle based on the upper direction in the figure, and the right rotation direction is an angle of + (plus) and the left rotation direction is − ( Minus) angle.

FIG. 2 is a graph showing an example of directivity characteristics 201 and 202 of beams forming the two sectors 101 and 102 in FIG. This FIG. 2 and later-described FIGS. 3 and 5 are the results of computer simulation. The half angle of the beam of the simulation specifications in FIGS. 2, 3 and 5 is 70 °, the side lobe level is −25 dB, the center frequency is 2 GHz, and the antenna spacing is 20 wavelengths. Further, angles φ _dir1 and φ _dir2 of directivity central directions B1 and B2 of beams forming sectors 101 and 102 are respectively -60 [°] and +60 [°] (the same applies to FIGS. 3 and 5 described later) ). Further, in the simulation specifications in FIG. 5, the transmission timing difference is 1 [μs], the subcarrier interval is 15 [kHz], and the number of subcarriers is 72 carriers.

  As shown in FIG. 2, in the sector boundary areas (cell boundary areas) A12, A23 and A31 which are areas of boundaries between adjacent sectors, the antenna gain is low compared to the central direction of the antenna directivity of each sector, Since the reception level of the terminal device is reduced, it is likely to be out of the coverage area of the wide area cell 100.

  Therefore, cell virtualization is virtually effective in constructing the wide area cell 100 by transmitting the same signal from the base station 10 for common signals to all the terminal devices 70 located in each of the sectors 101, 102, and 103. . However, when the same signal is transmitted to all the sectors 101, 102, and 103, a specific combined antenna pattern by phase combination appears depending on the arrangement of the antennas of each sector, and the average combined antenna gain is improved. However, there may be a case where the phase is combined in antiphase in a specific area and the reception level is reduced in the opposite direction.

FIG. 3 is a graph showing an example of the reception characteristic 210 when the same signal is transmitted at the same timing toward the directional characteristics 201 and 202 and the sectors 101 and 102 in FIG. For example, as shown in the reception characteristic 210 of FIG. 3, there is a possibility that a specific combined antenna pattern in which the reception level is greatly reduced periodically may occur in the sector boundary area A12 (see FIG. 1) near the angle φ _dir = 0 °. is there.

In order to suppress the generation of the specific combined antenna pattern, delay diversity which applies different transmission timing differences ΔDT between sectors is effective. For example, in the example of FIG. 4, the transmission timing difference ΔDT (= 1 [μs]) is given between the sectors 101 and 102 based on the sector 101, and the transmission timing difference ΔDT (= 2 μs) between the sectors 101 and 103. ] Is given. The transmission timing difference ΔDT between the sectors 102 and 103 is 1 [μs]. As described above, since the frequency selective fading occurs due to the delay diversity which gives different transmission timing differences ΔDT between the sectors, it is possible to prevent the reception level from being lowered in the entire passband even in the LOS environment or the like. For example, as shown in the improved reception characteristic 220 of FIG. 5, frequency selective fading occurs by giving a transmission timing difference ΔDT (= 1 [μs]) between the sectors 101 and 102, and the angle φ _dir is generated. It is possible to suppress a periodic decrease in reception level in the sector boundary area A12 (see FIG. 1) near 0 °.

  However, when the number of sectors formed with base station 10 at the center is increased, if an attempt is made to provide a fixed transmission timing difference between all the sectors, the transmission timing difference becomes large, and the resource element of the wireless communication frame is increased. As the effective guard interval length (CP length) becomes shorter, there is a risk that multipath resistance may be reduced.

  Therefore, in this embodiment, a plurality of cells (for example, 2 cells or 3 cells or more) are used so that transmission timings of downlink signals of adjacent cells do not become the same and the transmission timing difference is minimized. The transmission timing of the downlink signal of each cell is controlled by the repeated regular transmission pattern. For example, in the present embodiment, the first transmission timing difference ΔDT1 is given within the range equal to or less than the predetermined maximum time difference between adjacent sectors adjacent to each other in the circumferential direction in consideration of the adjacency relationship between sectors. Between non-adjacent sectors not adjacent to each other in the direction, a second transmission timing difference ΔDT2 is given within the range equal to or less than the maximum time difference. For example, between non-adjacent sectors, a transmission timing difference ΔDT2 equal to or smaller than the first transmission timing difference is given. A transmission timing difference may not be provided between non-adjacent sectors.

  Even if the number of sectors increases by setting the transmission timing difference ΔDT between adjacent sectors and non-adjacent cells in consideration of the adjacency relationship between sectors as in the present embodiment, the transmission timing difference between sectors can be obtained. It is possible to avoid the reduction of the combined gain (reception level) between sectors without increasing the

  FIG. 6 is an explanatory drawing showing an example of a first method (delay diversity method) of giving a transmission timing difference between the three sectors 101, 102, 103. As shown in FIG. The delay diversity scheme is a scheme in which the transmission timing of the downlink signal of each cell is controlled with respect to the time axis signal after inverse Fourier transform (for example, inverse fast Fourier transform (IFFT)). In the example of FIG. 6, the phases of the OFDM symbols 301a, 302a and 303a which are transmission parts for transmitting the same signal in the resource elements 301, 302 and 303 of the wireless communication frame of each sector are not changed, and By shifting the on-axis radio communication frame, the transmission timing difference ΔDT of the same signal between adjacent cells is given. Thus, in the method of shifting the wireless communication frame between adjacent cells to obtain the delay diversity effect, the above-mentioned maximum time difference is, for example, the guard interval (cyclic prefix) length in the resource element of the wireless communication frame (eg 4.69 [for example, μs]) or less may be set. In this case, it is possible to more reliably avoid the decrease in multipath resistance due to the shortening of the effective guard interval length.

  FIG. 7 is an explanatory view showing another example of a second method of giving a transmission timing difference (cyclic delay diversity (CDD) method) among the three sectors 101, 102, and 103. In FIG. The cyclic delay diversity (CDD) scheme is a scheme in which the head of the signal is delayed by controlling the phase of a subcarrier on which the signal is transmitted for all or part of the downlink signals of a plurality of cells. In the example of FIG. 7, the wireless communication frame of each sector is not shifted on the time axis, and an OFDM symbol 301a, which is a transmitting portion for transmitting the same signal in resource elements 301, 302 and 303 of the wireless communication frame of each sector. The same signal between adjacent cells by adjusting the blank time 301b, 302b, 303b before or after 302a, 303a to change the phase (relative position on the time axis) of the OFDM symbol 301a, 302a, 303a The transmission timing difference ΔDT of

  FIG. 8 is an explanatory view showing an example of a reception level reduction suppressing effect due to frequency selective fading in transmission timing difference assignment by a cyclic delay diversity system. In FIG. 8, in the cyclic delay diversity scheme, the phases of OFDM symbols in resource elements 301 and 302 of sectors 101 and 102 adjacent to each other are out of phase with each other. Therefore, the same signal S1 transmitted by the OFDM symbol (common channel) of each sector 101 and 102 and the signal S2 of its delayed wave are shifted on the time axis, and the combined waveform of each signal S1 and S2 on the frequency axis is also in phase. It is received by the terminal device in a shifted state. By receiving and combining the signals of the sectors shifted in this manner, the decrease in received power (received level) is reduced.

  Thus, in the method of changing the phase of the OFDM symbol (adding the phase difference) to obtain the delay diversity effect, it is possible to reliably avoid the decrease in multipath resistance due to the shortening of the effective guard interval length. it can. Further, in the cyclic delay diversity method, control may be performed by determining the presence or absence of the transmission timing difference due to the phase difference with respect to the same signal of the OFDM channel for each type of signal in the resource block of the wireless communication frame or for each channel. it can.

  FIG. 9 is an explanatory view showing one configuration example of a resource block 400 including a signal / channel to which transmission timing difference assignment by a cyclic delay diversity scheme is applied. In the example of FIG. 9, seven types of signals and channels surrounded by dashed lines 401 (CRS: cell reference signal, PDCCH: physical downlink control channel, PHICH: physical hybrid AQR indication channel, PCFICH: physical control format indication channel, SSS: For the secondary synchronization signal, PSS: primary synchronization signal, PBC: physical broadcast channel), it can be controlled by judging the presence or absence of transmission timing difference due to the phase difference to the same signal of the OFDM channel. Also, the same signal to which a transmission timing difference due to a phase difference is given is format indication information of downlink control information of PCFICH, downlink data delivery confirmation information signal of PHICH, downlink control information signal of PDCCH, cell reference signal (CRS) And at least one of synchronization signals (PSS, SSS) and system information signals (MIB, SIB).

  FIG. 10 is an explanatory drawing showing an example of the transmission timing difference to be given between the sectors in the base station 10 of the six sector system of this embodiment. In the example of FIG. 10, the base station 10 transmits a signal to the terminal device 70 located in each of six sectors 101 to 106 formed of six beams having directivity in six different directions. Also in the six-sector base station 10 shown in FIG. 10, the first transmission timing difference ΔDT1 is set within the range of a predetermined maximum time difference or less between adjacent sectors adjacent to each other in the circumferential direction, taking into consideration the adjacency relationship between sectors. Granted. On the other hand, between the non-adjacent sectors which are not adjacent to each other in the circumferential direction, the second transmission timing difference ΔDT2 is given within the range equal to or less than the maximum time difference, or the transmission timing difference is not given. By setting transmission timing differences ΔDT between adjacent sectors and non-adjacent cells in consideration of the adjacency relationship between sectors as described above, even if the number of sectors increases, the transmission timing difference between sectors becomes extremely extreme. It is possible to avoid a decrease in combined gain (reception level) between sectors without increasing the size.

  FIG. 11 is an explanatory view showing an example of a transmission timing difference to be provided between the sectors in the base station 10 of the six sector system of the comparative example. In the comparative example of FIG. 11, different transmission timing differences are provided between all the cells. Therefore, the transmission timing difference (= 5 [μs]) between the sector 101 and the sector 106 becomes larger than the guard interval (cyclic prefix) length (= 4.69 [μs]), and the sector 101 and the sector In the sector boundary area (cell boundary area) with the area 106, there is a risk that multipath resistance may be reduced due to the shortening of the effective guard interval length.

  FIGS. 12 (a) and 12 (b) are explanatory diagrams showing an example of transmission timing difference assignment when different signals are transmitted from each of the plurality of base stations 10 to 16 in the mobile communication system of the present embodiment. In this example, as shown in FIG. 12A, for example, the base station 10 transmits the signal A, which is the same signal, to the sectors 101 to 103 of the local station, and the base station 11 transmits the sector 111 to the local station. A signal B which is the same signal different from the signal A is transmitted to the signal 113. The same applies to the other base stations 12-16.

  Further, transmission timing differences (1 or 2 [μs]) within a range equal to or less than a predetermined maximum time difference are given between adjacent sectors in each of the base stations 10-16. Furthermore, transmission timing differences (1 or 2 [μs]) within a range not greater than a predetermined maximum time difference are also provided between cells of adjacent base stations. On the other hand, between the non-adjacent sectors of each of the base stations 10 to 16, the transmission timing difference (1 or 2 [μs]) within the range equal to or less than the maximum time difference is given or the transmission timing difference is not given.

  13 (a) and 13 (b) are explanatory views showing an example of transmission timing difference assignment when the same signal is transmitted from each of the plurality of base stations 10 to 16 in the mobile communication system of the present embodiment. In this example, as shown in FIG. 13A, for example, the base stations 10 and 11 transmit the signal A which is the same signal to the sectors 101 to 103 and 111 to 113 of the own station. The same applies to the other base stations 12-16.

  Further, transmission timing differences (1 or 2 [μs]) within a range equal to or less than a predetermined maximum time difference are given between adjacent sectors in each of the base stations 10-16. Furthermore, transmission timing differences (1 or 2 [μs]) within a range not greater than a predetermined maximum time difference are also provided between cells of adjacent base stations. On the other hand, between the non-adjacent sectors of each of the base stations 10 to 16, the transmission timing difference (1 or 2 [μs]) within the range equal to or less than the maximum time difference is given or the transmission timing difference is not given.

  FIG. 14 is an explanatory drawing showing an example of how three-dimensional wide-area cells 500 to 560 are formed from each of a plurality of base stations arranged in the upper sky of this embodiment. In FIG. 14, only the air base stations 50 to 52 forming the wide area cells 500 to 520 are illustrated, but other wide area cells 530 to 560 are formed by the air base stations. Also, in FIG. 14, only the footprint-like area of the wide-area cells 500 to 560 on the ground or in the sea is illustrated, but a cone or pyramid may be provided between the footprint-like area and the base station. A three-dimensional wide area cell having a three-dimensional shape is formed.

  In FIG. 14, the first base station 50 is provided in a solar plane type high altitude platform station (HAPS) 60 as a floating communication relay device. The second base station 51 is provided in the unmanned airship type HAPS 61. The third base station 52 is provided to a moored balloon (a moored HAPS) 62. Each of the base stations 50 to 52 is located in an airspace of a predetermined height, and forms a three-dimensional cell (three-dimensional area) in a cell formation target airspace of a predetermined height. The HAPS 60, 61 provided with the base stations 50, 51 are, for example, floating or flying in a high altitude airspace (floating airspace) of 100 [km] or less from the ground or sea surface under autonomous control or external control. Mounted on a controlled floating body (eg, a solar plane, an airship). The airspace in which the HAPSs 60 and 61 are located is, for example, a stratospheric airspace having an altitude of 11 km or more and 50 km or less. This airspace may be an airspace at an altitude of 15 [km] or more and 25 [km] or less at which the weather conditions are relatively stable, and particularly an airspace at an altitude of approximately 20 [km].

  FIG. 15 is an explanatory view showing an example of a transmission timing difference provided between a plurality of sectors constituting the three-dimensional wide area cells 500 to 560 of FIG. Among the plurality of sectors of the three-dimensional wide-area cells 500 to 560 of this example, transmission timing differences (1 or 2 [μs]) within a range equal to or less than a predetermined maximum time difference are provided between adjacent sectors. Furthermore, transmission timing differences (1 or 2 [μs]) within a range equal to or less than a predetermined maximum time difference are also provided between adjacent wide area cells. On the other hand, between the non-adjacent sectors, the transmission timing difference (1 or 2 [μs]) within the range equal to or less than the maximum time difference is given or the transmission timing difference is not given.

FIG. 16 is a block diagram showing an example of the configuration of the main part of the base station 10 of this embodiment. The other base stations 11 to 16 and 50 to 52 can be configured similarly.
In FIG. 16, the base station 10 includes an antenna unit 190, a transmission unit 191, a control unit 192, and a data reception unit 193. The antenna unit 190 radiates a radio wave of a transmission signal of a predetermined frequency generated for each sector by the transmission unit 191 toward each sector in a beam shape. The antenna unit 190 may be configured with an antenna common to each sector, or may be configured with a plurality of independent antennas for each sector.

  The transmission unit 191 transmits various signals to each of a plurality of sectors. The transmission unit 191 includes, for example, a baseband unit and a high frequency amplifier. The baseband unit generates a transmission signal for each sector by modulating transmission data based on a predetermined wireless transmission scheme (for example, a wireless transmission scheme defined in LTE, LTE-Advanced, 5G, etc. of 3GPP). . The high frequency amplifier amplifies the transmission signal for each sector generated in the baseband unit to a predetermined level. The amplified transmission signal is transmitted as a beam to each of a plurality of sectors via the antenna unit 190.

  The control unit 192 controls the transmission of the signal by the transmission unit 191. In this embodiment, the control unit 192 regularly repeats a plurality of sectors or more (for example, 3 sectors or more) so that transmission timings of downlink signals of adjacent sectors do not become the same and the transmission timing difference is minimized. The transmission timing of the downlink signal of each sector is controlled by a proper transmission pattern. For example, when transmitting the same signal to each of a plurality of sectors, the control unit 192 has non-adjacent cells not adjacent to each other, having transmission timing differences within a predetermined maximum time difference or less between adjacent cells adjacent to each other. The transmission of the same signal to each of the plurality of sectors is controlled so as to have a transmission timing difference within the range not more than the maximum time difference or no transmission timing difference therebetween.

  The data reception unit 193 receives various data to be transmitted from the core network of mobile communication and the like.

  The apparatus including the transmission unit 191 and the control unit 192 in FIG. 16 may be a repeater as a wireless relay station that relays a signal transmitted and received by the base station. In this case, the transmitting unit 191 amplifies the downlink signal received from the base station to a predetermined level, and transmits it in a beam form to each of a plurality of sectors via the antenna unit 190. In addition, the control unit 192 regularly transmits transmission patterns in a plurality of sectors or more (for example, three or more sectors) so that transmission timings of downlink signals of adjacent sectors are not the same and the transmission timing difference is minimized. Control the transmission timing of the downlink signal of each sector. The repeater may be incorporated in a float or flying object located above the balloon 62, drone, HAPS 60, 61, artificial satellite, etc. (see FIG. 14).

  FIG. 17 is a block diagram showing a configuration example of main parts of a wireless device according to another embodiment. The radio apparatus of this embodiment includes a fixed base station 90 on the ground or the sea having the control unit, and a repeater slave unit 72 as a radio relay station having the transmission unit. The fixed base station 90 and the repeater slave unit 72 can communicate with the repeater master unit 71 on the ground or at the sea via a wireless feeder link circuit.

  In FIG. 17, the fixed base station 90 includes a feeder link communication unit 900, a transmission signal generation unit 901, a control unit 902, and a data reception unit 903. The feeder link communication unit 900 communicates with the repeater slave unit 72 via the repeater master unit 71 and the wireless feeder link line. The transmission signal generation unit 901 modulates transmission data based on a predetermined wireless transmission scheme (for example, a wireless transmission scheme defined in 3GPP LTE, LTE-Advanced, 5G, etc.) to transmit a transmission signal for each sector. Generate

  The control unit 902 controls generation and transmission of signals by the transmission signal generation unit 901. In the present embodiment, the control unit 902 regularly repeats at least a plurality of sectors (for example, three or more sectors) so that the transmission timings of downlink signals of adjacent sectors are not the same and the transmission timing difference is minimized. The transmission timing of the downlink signal of each sector is controlled by a proper transmission pattern. For example, when transmitting the same signal to each of a plurality of sectors, the control unit 9022 has non-adjacent cells not adjacent to each other, having a transmission timing difference within a predetermined maximum time difference between adjacent cells adjacent to each other. The transmission of the same signal to each of the plurality of sectors is controlled so as to have a transmission timing difference within the range not more than the maximum time difference or no transmission timing difference therebetween.

  The data reception unit 903 receives various data to be transmitted from the core network of mobile communication and the like.

  Further, in FIG. 17, the repeater slave unit 72 includes an antenna unit 720, a transmission unit 721, and a feeder link communication unit 722. The antenna unit 720 radiates a radio wave of a transmission signal of a predetermined frequency received from the base station 90 toward each sector in a beam shape. The antenna unit 720 may be configured with an antenna common to each sector, or may be configured with a plurality of independent antennas for each sector.

  The transmission unit 721 transmits various signals to each of a plurality of sectors. The transmission unit 721 converts the frequency of the transmission signal for each sector and then amplifies the frequency to a predetermined level. The amplified transmission signal is transmitted as a beam to each of a plurality of sectors via the antenna unit 720.

  In the embodiment of FIG. 17, the repeater slave unit 72 may be incorporated in a float or flying object located above the balloon 62, drone, HAPS 60, 61, artificial satellite, etc. (figure 14).

  As described above, according to each of the above embodiments, a constant first transmission timing difference within a range not greater than a predetermined maximum time difference is provided between adjacent sectors adjacent to each other, and the maximum time difference between non-adjacent sectors not adjacent to each other The second transmission timing difference within the following range is given or the transmission timing difference is not given. By setting transmission timing differences between adjacent sectors and between non-adjacent cells in consideration of the adjacency relationship between sectors as described above, transmission timings of downlink signals of adjacent sectors are not equal and transmission timing differences. The transmission timing of the downlink signal of each sector is controlled by a regular transmission pattern repeated in a plurality of cells or more (for example, 3 cells or more) so as to minimize By this control, even if the number of sectors is increased, it is possible to avoid the reduction of the combined gain (reception level) between the sectors without extremely increasing the transmission timing difference between the sectors. When transmitting the same downlink signal by OFDM transmission from a base station using the SFN method to all or a part of a plurality of sectors formed by the base station, the reception level is reduced throughout each cell. At the same time, it is possible to suppress the decrease in multipath resistance.

  Note that the processing steps and communication systems described in this specification, and components of the communication system, radio apparatus, base station, radio relay station (repeater, repeater slave unit, repeater master unit) and terminal apparatus (user apparatus mobile station, mobile unit) Can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof. For example, control and processing in a wireless apparatus such as a base station according to the present embodiment may be performed by reading and executing a predetermined program in hardware described later, or executing a predetermined program embedded in hardware described later. It is realized by doing.

  With regard to hardware implementation, means such as a processing unit used to realize the above processes and components in an entity (for example, various wireless communication devices, Node Bs, terminals, hard disk drive devices, or optical disk drive devices) One or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors , A controller, a microcontroller, a microprocessor, an electronic device, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

  Also, for firmware and / or software implementations, means such as processing units used to implement the above components may be programs (eg, procedures, functions, modules, instructions for performing the functions described herein) , Etc.) may be implemented. In general, any computer / processor readable medium tangibly embodying firmware and / or software codes such as a processing unit or the like used to implement the above described processes and components described herein. May be used to implement For example, firmware and / or software code may be stored in memory, for example on a controller, and executed by a computer or processor. The memory may be implemented inside a 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) ), Computer- and processor-readable media such as FLASH memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage, etc. Good. The code may be executed by one or more computers or processors, and may cause the computers or processors to perform certain aspects of the functionality described herein.

  Additionally, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

10 base stations 11, 12, 13, 14, 15, 16 base stations 50, 51, 52 base stations 60 solar plane type HAPS
61 Unmanned airship type HAPS
62 Mooring balloon 70 Terminal equipment 71 Repeater master unit 72 Repeater slave unit 90 Fixed base station 100 Wide area cell 101, 102, 103 Sector (sector cell)
104, 105, 105, 106 sectors (sector cells)
190 antenna unit 191 transmission unit 192 control unit 193 data reception unit 301, 302, 303 resource element 301a, 302a, 303a OFDM symbol 400 resource block 500, 510, 520, 530, 540, 550, 560 wide area cell A12, A23, A31 Sector boundary area A34, A45, A56, A61 Sector boundary area B1, B2, B3 Directional central direction of beam

Claims (8)

Radio apparatus using a single frequency network (SFN) scheme in which all or part of signals transmitted by orthogonal frequency division multiplexing (OFDM) transmission in downlink of each of a plurality of sector cells constituting a wide area cell is the same among sector cells And
A transmitter configured to form the plurality of sector cells and transmitting a signal to a terminal device located in each sector cell via a wireless link;
Transmission timing of the downlink signal of each sector cell in a regular transmission pattern repeated in the plurality of sector cells so that transmission timings of downlink signals of adjacent sector cells are not the same and to minimize the transmission timing difference And a control unit that controls the wireless communication device. In the wireless device of claim 1,
A control method of transmission timing of downlink signal of each sector cell is a delay diversity method in which transmission timing is controlled in each sector cell for transmission signal on time axis after inverse Fourier transform. In the wireless device of claim 2,
The wireless device, wherein the maximum value of the transmission timing difference between each sector cell of the downlink signal of the base station of each sector cell is equal to or less than the cyclic prefix length. In the wireless device of claim 1,
The control method of the transmission timing of the downlink signal of each sector cell controls the phase of the subcarrier to which the signal is transmitted for all or part of the downlink signals of the plurality of sector cells, thereby controlling the head of the signal. A radio apparatus characterized in that it is a cyclic delay diversity (CDD) system that cyclically delays within an OFDM symbol. The wireless device according to any one of claims 1 to 4,
The wireless device is characterized by being a base station for mobile communication, a wireless relay station for relaying a signal transmitted and received by the base station, or a digital broadcast device provided with the transmitting unit and the control unit. Wireless device. The wireless device according to any one of claims 1 to 4,
A base station of mobile communication provided with the control unit;
A radio apparatus comprising: a pre-transmission unit; and a radio relay station relaying signals transmitted and received by the base station. The wireless device according to any one of claims 1 to 6,
The wireless transmission device is characterized in that the transmitting unit is fixedly arranged on the ground or the sea, incorporated in a mobile moving on the ground or the sea, or incorporated in a floating body or a flying object located above.   A wireless system comprising a plurality of wireless devices according to any one of claims 1 to 7.