Footprint fixation control limited to specific channels considering movement and rotation of HAPS
When there is a movement or attitude change of an upper-airspace staying type communication relay apparatus, it is suppressed of an increase in control signals and disconnection of communication with a terminal apparatus in a cell configuring a service area, and it is reduced of a circuit scale and power consumption of a base-station processing section. The base-station processing section of the communication relay apparatus performs, with respect to a radio resource part for control communication by which a communication is performed with plural terminal apparatuses located in a cell via a single or plural beams for control among downlink and uplink radio resources used for service links, a footprint fixation control for performing a precoding and a postcoding so as to fix a position of a footprint corresponding to the beam for control, based on information on at least one of a position and attitude of the communication relay apparatus, and does not perform the footprint fixation control on the basis of the information on the at least one of the position and attitude, with respect to downlink and uplink radio resource parts other than the radio resource part for control communication.
1. An upper-airspace staying type communication relay apparatus for wirelessly communicating with a terminal apparatus, comprising:
an array antenna having plural antenna elements, the array antenna forming a service link cell capable of performing a radio communication with the terminal apparatus;
an information obtaining section for obtaining information on at least one of a position and attitude of the communication relay apparatus; and
a base-station processing section for performing a baseband process including a process for applying a precoding for beamforming in a frequency domain to a downlink transmission signal to be transmitted via the array antenna, and a process of applying a postcoding for beamforming in a frequency domain to an uplink reception signal received via the array antenna,
wherein the base-station processing section:
performs, with respect to a radio resource part for control communication by which a communication via a single or plural beams for control formed for the cell is performed among downlink radio resources used for the service link, a footprint fixation control for performing a precoding for beamforming in the frequency domain so as to fix a position of a footprint corresponding to the beam for control, based on information on at least one of the position and attitude of the communication relay apparatus obtained by the information obtaining section;
does not perform, with respect to downlink radio resource parts other than the radio resource part for control communication, the footprint fixation control on the basis of the information on at least one of the position and attitude of the communication relay apparatus;
performs, with respect to a radio resource part for control communication by which an uplink communication via a single or plural beams for control formed for the cell is performed among uplink radio resources used for the service link, a footprint fixation control for performing a postcoding for beamforming in the frequency domain so as to fix a position of a footprint corresponding to the beam for control, based on information on at least one of the position and attitude of the communication relay apparatus obtained by the information obtaining section; and
does not perform, with respect to uplink radio resource parts other than the radio resource part for control communication, the footprint fixation control on the basis of the information on at least one of the position and attitude of the communication relay apparatus, and
wherein, in the footprint fixation control, a beamforming is performed so that a main beam of the beam for control is directed toward a target point set in advance.
2. The communication relay apparatus according to claim 1 ,
wherein the radio resource part for downlink control communication includes a radio resource part to which a synchronization signal (SS) and a broadcast channel (PBCH) are assigned, and
wherein the radio resource part for downlink control communication includes a radio resource part to which a physical downlink control channel (PDCCH) is assigned, and a radio resource part to which a physical downlink shared channel (PDSCH) before completion of initial access from the terminal apparatus to the cell is assigned.
3. The communication relay apparatus according to claim 1 or 2 ,
wherein the radio resource part for uplink control communication includes a radio resource part to which a physical random access channel (PRACH) is assigned, and
wherein the radio resource part for uplink control communication includes a radio resource part to which a physical uplink control channel (PUCCH) is assigned, and a radio resource part to which a physical uplink shared channel (PUSCH) before completion of initial access from the terminal apparatus to the cell is assigned.
4. The communication relay apparatus according to claim 1 ,
wherein the communication relay apparatus:
pre-calculates and stores beamforming (BF) weights in association with each of plural sets of positions and attitudes different from each other on a predicted moving route of the communication relay apparatus with reference to a position of a service area; and
selects a beamforming (BF) weight corresponding to the position and attitude of the communication relay apparatus obtained by the information obtaining section, from the stored beamforming (BF) weights corresponding to each of the plural sets of positions and attitudes.
5. The communication relay apparatus according to claim 2 ,
wherein the radio resource part for uplink control communication includes a radio resource part to which a physical random access channel (PRACH) is assigned, and
wherein the radio resource part for uplink control communication includes a radio resource part to which a physical uplink control channel (PUCCH) is assigned, and a radio resource part to which a physical uplink shared channel (PUSCH) before completion of initial access from the terminal apparatus to the cell is assigned.
6. The communication relay apparatus according to claim 2 ,
wherein the communication relay apparatus:
pre-calculates and stores beamforming (BF) weights in association with each of plural sets of positions and attitudes different from each other on a predicted moving route of the communication relay apparatus with reference to a position of a service area; and
selects a beamforming (BF) weight corresponding to the position and attitude of the communication relay apparatus obtained by the information obtaining section, from the stored beamforming (BF) weights corresponding to each of the plural sets of positions and attitudes.
7. The communication relay apparatus according to claim 3 ,
wherein the communication relay apparatus:
pre-calculates and stores beamforming (BF) weights in association with each of plural sets of positions and attitudes different from each other on a predicted moving route of the communication relay apparatus with reference to a position of a service area; and
selects a beamforming (BF) weight corresponding to the position and attitude of the communication relay apparatus obtained by the information obtaining section, from the stored beamforming (BF) weights corresponding to each of the plural sets of positions and attitudes.
8. The communication relay apparatus according to claim 5 ,
wherein the communication relay apparatus:
pre-calculates and stores beamforming (BF) weights in association with each of plural sets of positions and attitudes different from each other on a predicted moving route of the communication relay apparatus with reference to a position of a service area; and
selects a beamforming (BF) weight corresponding to the position and attitude of the communication relay apparatus obtained by the information obtaining section, from the stored beamforming (BF) weights corresponding to each of the plural sets of positions and attitudes.