1. A method for signal transmission in wireless communication, the method comprising:determining a sequence {fn} comprising 2×N elements, wherein fn is an element of {fn}, N is a positive integer and an even number, n is an integer, and 0?n?2×N?1;

mapping the sequence {fn} to 2×N subcarriers; and

sending, on the 2×N subcarriers, a signal that carries the sequence {fn};

wherein the sequence {fn} comprises:

when n is an odd number, fn=A1·xn·exp(2?·j·?·n);

when n is an even number, fn=A2·xn·exp(2?·j·?·n);

A1 and A2 are non-zero complex numbers, ? is a real number, j=??1, exp(j×h) represents ej×h, and h is any real number; and {xn} is a sequence composed of xn, and meets at least one of the following conditions:

condition 1: when n is an even number greater than or equal to 0 and less than or equal to N?1,

xn+N=?×j×xn;

when n is an odd number greater than or equal to 0 and less than or equal to N?1,

xn+N=??×j×xn;

wherein a=1 or 1, j=??1, and N is a positive integer and an even number; and

condition 2: when N=6,

c is a non-zero complex number, 0?n?2, and{y0 y1 y2 y3 y4 y5} is one of the following sequences:

{2 0 6 2 4 6},

{6 0 2 6 4 2},

{0 6 4 4 2 0},

{2 6 6 4 4 0},

{6 2 2 4 4 0},

{6 6 2 4 0 0},

{2 2 6 4 0 0},

{4 2 0 4 6 0},

{0 2 4 0 6 4},

{2 0 6 6 4 2},

{4 0 0 6 6 2},

{0 4 4 6 6 2},

{0 0 4 6 2 2},

{4 4 0 6 2 2},

{6 4 2 6 0 2},

{2 4 6 2 0 6},

{4 2 0 0 6 4},

{6 2 2 0 0 4},

{2 6 6 0 0 4},

{2 2 6 0 4 4},

{6 6 2 0 4 4},

{0 6 4 0 2 4},

{4 6 0 4 2 0},

{6 4 2 2 0 6},

{0 4 4 2 2 6},

{4 0 0 2 2 6},

{4 4 0 2 6 6},

{0 0 4 2 6 6}.