Abstract: A method for sounding-interval adaptation using link quality for use in an apparatus is provided. The apparatus includes a sounding transceiver. The method includes the following steps: periodically transmitting a sounding packet to a beamformee through a downlink channel from the apparatus to the beamformee according to a first sounding interval; in response to the sounding transceiver receiving a data packet or a report packet from the beamformee, obtaining a current first channel profile from the received data packet or the received report packet; and adaptively adjusting the first sounding interval according to a first mobility indicator which is calculated according to the current first channel profile and the previous first channel profile.

Abstract: A method for sounding-interval adaptation using link quality for use in an apparatus is provided. The apparatus includes a sounding transceiver. The method includes the following steps: periodically transmitting a sounding packet to a beamformee through a downlink channel from the apparatus to the beamformee according to a first sounding interval; in response to the sounding transceiver receiving a data packet or a report packet from the beamformee, obtaining a current first channel profile from the received data packet or the received report packet; and adaptively adjusting the first sounding interval according to a first mobility indicator which is calculated according to the current first channel profile and the previous first channel profile.

Abstract: A method for sounding-interval adaptation using link quality for use in an apparatus is provided. The apparatus includes a sounding transceiver. The method includes the following steps: periodically transmitting a sounding packet to a beamformee through a downlink channel from the apparatus to the beamformee using a first sounding interval; in response to the sound transceiver successfully receiving a report packet from the beamformee to respond to the sounding packet, obtaining a current first channel profile from the report packet, and calculating a first LQ (link quality) value of the beamformee using the current first channel profile and a previous first channel profile; searching an LQ-mapping table using the first LQ value to obtain a second sounding interval; and adaptively adjusting the first sounding interval using the second sounding interval in response to a comparison result of the current first channel profile and the previous first channel profile.

Abstract: A method for sounding-interval adaptation using link quality for use in an apparatus is provided. The apparatus includes a sounding transceiver. The method includes the following steps: periodically transmitting a sounding packet to a beamformee through a downlink channel from the apparatus to the beamformee using a first sounding interval; in response to the sound transceiver successfully receiving a report packet from the beamformee to respond to the sounding packet, obtaining a current first channel profile from the report packet, and calculating a first LQ (link quality) value of the beamformee using the current first channel profile and a previous first channel profile; searching an LQ-mapping table using the first LQ value to obtain a second sounding interval; and adaptively adjusting the first sounding interval using the second sounding interval in response to a comparison result of the current first channel profile and the previous first channel profile.

Abstract: An optical communication system suitable for a coherent optical satellite communication is configured to include an optical transmission device having a laser signal generator, a first reference laser signal generator having a first local oscillating laser signal generator and an automatic frequency controller, an optical receiving device, and a second reference optical signal generator having a second local oscillating laser signal generator. The first reference local oscillating laser signal generator and the automatic frequency controller are used to generate a fixed beat reference optical signal, and thus the optical receiving device is capable of locking the transmitted laser signal according to the fixed beat reference laser signal in a way of heterodyne receiving so as to demodulate the transmitted signal frequency accurately and resolve the problem of laser frequency drifting.

Abstract: A coherent optical communication receiver of a satellite optical communication system, having a telescope, an automatic frequency control circuit and a frequency shift keying demodulator. The automatic frequency control circuit has a local oscillating laser, a light polarization controller, a optical coupler, a photo-detector, a microwave matching network, a microwave mixer, a frequency discriminator and a low pass frequency filter. The coherent optical communication receiver can receive a frequency control signal of a distant laser signal to perform a heterodyne receiving between the emitter and the receiver distant away from each other. With the consideration of the decay of vibration and atmosphere, the quality of the satellite optical communication can still be maintained. The structure and fabrication of the receiver are simple with a low fabrication cost, and the receiver is suitable for being applied to high speed satellite communication system.

Abstract: A coherent optical communication receiver of a satellite optical communication system, having a telescope, an automatic frequency control circuit and a frequency shift keying demodulator. The automatic frequency control circuit has a local oscillating laser, a light polarization controller, a optical coupler, a photo-detector, a microwave matching network, a microwave mixer, a frequency discriminator and a low pass frequency filter. The coherent optical communication receiver can receive a frequency control signal of a distant laser signal to perform a heterodyne receiving between the emitter and the receiver distant away from each other. With the consideration of the decay of vibration and atmosphere, the quality of the satellite optical communication can still be maintained. The structure and fabrication of the receiver are simple with a low fabrication cost, and the receiver is suitable for being applied to high speed satellite communication system.