A target constellation diagram determining method, comprising: • determining, by a receiving device for received 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, a detection region of each constellation point in the alternative constellation diagram based on a position of the training data in the alternative constellation diagram; and obtaining a cumulative distance corresponding to the alternative constellation diagram based on a distance between the detection regions of the constellation points (step 401), wherein the 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, by the receiving device, the alternative constellation diagram into a plurality of sectors (step 601); ∘ determining, by the receiving device 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; and if the quantity is greater than or equal to 2, calculating a distance between the detection regions in the first sector, to obtain a cumulative distance corresponding to the first sector; and if the quantity is less than 2, directly determining 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 (step 602), and ∘ determining, by the receiving device, that a sum of cumulative distances corresponding to the plurality of sectors is the cumulative distance corresponding to the alternative constellation diagram (step 603); • after obtaining cumulative distances corresponding to the alternative constellation diagrams in the alternative constellation diagram set, determining, by the receiving device, that an alternative constellation diagram with a largest cumulative distance is a target constellation diagram, and sending a notification message to the sending device, wherein the notification message is used to notify the sending device of the target constellation diagram (step 402). • determining, by a receiving device for received 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, a detection region of each constellation point in the alternative constellation diagram based on a position of the training data in the alternative constellation diagram; and obtaining a cumulative distance corresponding to the alternative constellation diagram based on a distance between the detection regions of the constellation points (step 401), wherein the 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, by the receiving device, the alternative constellation diagram into a plurality of sectors (step 601); ∘ determining, by the receiving device 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; and if the quantity is greater than or equal to 2, calculating a distance between the detection regions in the first sector, to obtain a cumulative distance corresponding to the first sector; and if the quantity is less than 2, directly determining 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 (step 602), and ∘ determining, by the receiving device, that a sum of cumulative distances corresponding to the plurality of sectors is the cumulative distance corresponding to the alternative constellation diagram (step 603); ∘ radially dividing, by the receiving device, the alternative constellation diagram into a plurality of sectors (step 601); ∘ determining, by the receiving device 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; and if the quantity is greater than or equal to 2, calculating a distance between the detection regions in the first sector, to obtain a cumulative distance corresponding to the first sector; and if the quantity is less than 2, directly determining 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 (step 602), and ∘ determining, by the receiving device, that a sum of cumulative distances corresponding to the plurality of sectors is the cumulative distance corresponding to the alternative constellation diagram (step 603); • after obtaining cumulative distances corresponding to the alternative constellation diagrams in the alternative constellation diagram set, determining, by the receiving device, that an alternative constellation diagram with a largest cumulative distance is a target constellation diagram, and sending a notification message to the sending device, wherein the notification message is used to notify the sending device of the target constellation diagram (step 402).