Wireless communications method and system

A wireless communications system comprising:

• a transmit end, wherein the transmit end comprises a transmitter having at least two antennas, the transmitter configured to transmit M narrow beams with different spatial directions according to a quality of service (QoS) requirement, and to switch a transmit mode according to a preset switching rule, wherein a set of the spatial directions of the M narrow beams forms the transmit mode;
• a receive end, wherein the receive end comprises a receiver having at least two antennas, the receiver configured to receive N beams according to the QoS requirement;
• and
• a transmission channel for transmitting the M narrow beams and the N beams between the receive end and the transmit end,
• wherein the receive end calculates a channel quality of the transmission channel in different transmit modes, searches for a transmit mode that meets the QoS requirement, and feeds back the transmit mode to the transmit end, or feeds back a transmit mode with optimal channel quality to the transmit end if the channel quality corresponding to all transmit modes is traversed and no transmit mode that meets the QoS requirement is found;
• and
• wherein both the M narrow beams and the N beams are integers greater than or equal to 1, and
• wherein searching for the transmit mode that meets the QoS requirement and feeding back the transmit mode to the transmit end, or feeding back the transmit mode with optimal channel quality to the transmit end when transmission channel quality corresponding to all transmit modes is traversed but no transmit mode that meets the QoS requirement is found comprises:
• when a channel quality of the transmit mode meets the QoS requirement, feeding back to the transmit end, the transmit mode that meets the QoS requirement and channel quality information corresponding to the transmit mode, or otherwise, sorting the transmit modes according to the channel quality and entering a next transmit mode for searching;
• and
• when no transmit mode that meets the QoS requirement is found after all transmit modes in the preset switching rule are traversed, feeding back a transmit mode that is obtained by sorting and that has an optimal channel capacity, and corresponding channel quality to the transmit end by using a wide beam.