A method, comprising: receiving, by a terminal, a first message that comprises a set of channel quality threshold values, wherein the set of channel quality threshold values comprises at least one channel quality threshold value; and sending, by the terminal, a random access preamble, Msg1, message, characterized in that the Msg1 message comprises a plurality of first structures and each of the plurality of first structures comprises four symbol groups, a subcarrier index occupied by a first symbol group of the four symbol groups, in a first structure of the plurality of first structures having an odd index, is selected from a first subcarrier set, wherein a number of subcarriers comprised in the first subcarrier set is 12, and a subcarrier index occupied by the first symbol group of the four symbol groups, in a first structure of the plurality of first structures having an even index, is selected from a second subcarrier set, wherein the second subcarrier set is determined according to one of following rules: in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an even index in the first subcarrier set, the second subcarrier set comprises subcarriers having odd indexes in the first subcarrier set; or in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an odd index in the first subcarrier set, the second subcarrier set comprises subcarriers having even indexes in the first subcarrier set. receiving, by a terminal, a first message that comprises a set of channel quality threshold values, wherein the set of channel quality threshold values comprises at least one channel quality threshold value; and sending, by the terminal, a random access preamble, Msg1, message, characterized in that the Msg1 message comprises a plurality of first structures and each of the plurality of first structures comprises four symbol groups, a subcarrier index occupied by a first symbol group of the four symbol groups, in a first structure of the plurality of first structures having an odd index, is selected from a first subcarrier set, wherein a number of subcarriers comprised in the first subcarrier set is 12, and a subcarrier index occupied by the first symbol group of the four symbol groups, in a first structure of the plurality of first structures having an even index, is selected from a second subcarrier set, wherein the second subcarrier set is determined according to one of following rules: in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an even index in the first subcarrier set, the second subcarrier set comprises subcarriers having odd indexes in the first subcarrier set; or in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an odd index in the first subcarrier set, the second subcarrier set comprises subcarriers having even indexes in the first subcarrier set. in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an even index in the first subcarrier set, the second subcarrier set comprises subcarriers having odd indexes in the first subcarrier set; or in a condition that a subcarrier index occupied by the first symbol group in the first structure having an odd index before the first structure having the even index corresponds to a subcarrier having an odd index in the first subcarrier set, the second subcarrier set comprises subcarriers having even indexes in the first subcarrier set.