Target constellation diagram determining method, data sending method, and apparatus

A receiving device, comprising a communications interface and a processor, wherein

• the communications interface is configured to receive training data that is generated and sent by a sending device based on each of a plurality of alternative constellation diagrams in an alternative constellation diagram set;
• and
• the processor is configured to:
• for the received training data that is generated and sent by the sending device based on each alternative constellation diagram in the alternative constellation diagram set,
• determine a detection region of each of a plurality of constellation points in the alternative constellation diagram based on a position of the training data in the alternative constellation diagram;
• obtain a cumulative distance corresponding to the alternative constellation diagram based on a distance between the detection regions of the plurality of constellation points wherein obtaining the cumulative distance corresponding to the alternative constellation diagram based on the distance between the detection regions of the constellation points in the alternative constellation diagram comprises:
• radially dividing the alternative constellation diagram into a plurality of sectors;
• determining, for a first sector in the plurality of sectors, whether a quantity of detection regions in the first sector is greater than or equal to 2;
• if the quantity is greater than or equal to 2, calculate a distance between the detection regions in the first sector, to obtain a cumulative distance corresponding to the first sector;
• if the quantity is less than 2, directly determine to set a cumulative distance corresponding to the first sector to a preset distance threshold, wherein the first sector is any sector in the plurality of sectors;
• and
• determining that a sum of cumulative distances corresponding to the plurality of sectors is the cumulative distance corresponding to the alternative constellation diagram;
• after obtaining the cumulative distance corresponding to each alternative constellation diagrams in the alternative constellation diagram set, determine an alternative constellation diagram of the plurality of alternative constellation diagrams with a largest cumulative distance as a target constellation diagram, and
• send a notification message to the sending device by using the communications interface, wherein the notification message is configured for notifying the sending device of the target constellation diagram, so that the sending device modulates to-be-sent data based on the target constellation diagram.