A method for generating a jointly modulated symbol, performed by a device, comprising: jointly modulating and mapping a first modulation bit sequence b 0 (i), b 0 (i+1) and a second modulation bit sequence b 1 (i), b 1 (i+1),...b 1 (i+n), which are m bits in total, to obtain a combined constellation x, wherein i is a natural number, n ∈ {1,3,5}, m ∈ {4,6,8}; wherein the combined constellation x is obtained according to the following formula: x = sign 1 × c I − d + sign 2 × c Q − d; wherein c and d are parameters related to power allocation of the first modulation bit sequence and the second modulation bit sequence in the combined constellation x; I and Q are coordinates of a constellation point of the second modulation bit sequence b 1 (i), b 1 (i+1),...b 1 (i+n); and wherein sign1 and sign2 are obtained by the first modulation bit sequence b0(i), b0(i+1), when the first modulation bit sequence b 0 (i), b 0 (i+1) is 00, sign1=-1 and sign2=-j; when the first modulation bit sequence b 0 (i), b 0 (i+1) is 10, sign1=1 and sign2=-j; when the first modulation bit sequence b 0 (i), b 0 (i+1) is 01, sign1=-1 and sign2=j; and when the first modulation bit sequence b 0 (i), b 0 (i+1) is 11, sign1=1 and sign2=j; sign 1 = − 1 1 − b 0 i sign 2 = j × − 1 1 − b 0 i + 1; or, sign1 and sign2 are obtained by a quadrature phase shift keying, QPSK, symbol mapped by the first modulation bit sequence b0(i), b0(i+1), wherein modulation of the first modulation bit sequence is QPSK, when a constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = 2 2 + j 2 2, sign1=-1, sign2=-j; when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = − 2 2 + j 2 2, sign1=1, sign2=-j; when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = − 2 2 − j 2 2, sign1=1, sign2=j; and when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = 2 2 − j 2 2, sign1=-1, sign2=j; sign 1 = sign 3 sign real s 1 sign 2 = j × sign 3 sign imag s 1, wherein sign() denotes a sign function, sign3() denotes an inverse function of the sign function. jointly modulating and mapping a first modulation bit sequence b 0 (i), b 0 (i+1) and a second modulation bit sequence b 1 (i), b 1 (i+1),...b 1 (i+n), which are m bits in total, to obtain a combined constellation x, wherein i is a natural number, n ∈ {1,3,5}, m ∈ {4,6,8}; wherein the combined constellation x is obtained according to the following formula: x = sign 1 × c I − d + sign 2 × c Q − d; wherein c and d are parameters related to power allocation of the first modulation bit sequence and the second modulation bit sequence in the combined constellation x; I and Q are coordinates of a constellation point of the second modulation bit sequence b 1 (i), b 1 (i+1),...b 1 (i+n); and wherein sign1 and sign2 are obtained by the first modulation bit sequence b0(i), b0(i+1), when the first modulation bit sequence b 0 (i), b 0 (i+1) is 00, sign1=-1 and sign2=-j; when the first modulation bit sequence b 0 (i), b 0 (i+1) is 10, sign1=1 and sign2=-j; when the first modulation bit sequence b 0 (i), b 0 (i+1) is 01, sign1=-1 and sign2=j; and when the first modulation bit sequence b 0 (i), b 0 (i+1) is 11, sign1=1 and sign2=j; sign 1 = − 1 1 − b 0 i sign 2 = j × − 1 1 − b 0 i + 1; or, sign1 and sign2 are obtained by a quadrature phase shift keying, QPSK, symbol mapped by the first modulation bit sequence b0(i), b0(i+1), wherein modulation of the first modulation bit sequence is QPSK, when a constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = 2 2 + j 2 2, sign1=-1, sign2=-j; when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = − 2 2 + j 2 2, sign1=1, sign2=-j; when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = − 2 2 − j 2 2, sign1=1, sign2=j; and when the constellation point of the first modulation bit sequence b 0 (i), b 0 (i+1) is s 1 = 2 2 − j 2 2, sign1=-1, sign2=j; sign 1 = sign 3 sign real s 1 sign 2 = j × sign 3 sign imag s 1, wherein sign() denotes a sign function, sign3() denotes an inverse function of the sign function.