Patent ID: 8687646

Claim:
A method for bit and power allocation, comprising: determining a set of candidate modulation modes for sub-channels; constructing a signal-to-noise ratio (SNR) lookup table according to a predetermined target bit error rate (BER), the SNR lookup table containing a relationship of an SNR and the number of bits corresponding to a modulation mode in the set of candidate modulation modes at the predetermined target BER; obtaining normalized SNRs on the sub-channels; initializing the numbers of bits for the sub-channels; initializing powers for the sub-channels according to the numbers of bits for the sub-channels, the normalized SNRs on the sub-channels and the SNR lookup table; and adjusting the numbers of bits and the powers for the sub-channels in accordance with a principle of maximizing power utilization rate, the adjusted numbers of bits and powers for the sub-channels being taken as a result of bit and power allocation for the sub-channels, wherein for an M-QAM modulation mode, the SNR lookup table is constructed with BER calculation formulas of SNR=[ erfc âˆ’1 (2BER target )] 2 when the number of bits is 1; SNR = ( 3 + 3 ) â¡ [ erfc - 1 â¡ ( 16 11 â¢ BER target ) ] 2 â¢ â¢ or SNR = 6 [ erfc - 1 â¡ ( 12 5 â¢ BER target ) ] 2 when the number of bits is 3; SNR = 2 3 â¢ ( 2 2 â¢ p - 1 ) â¡ [ erfc - 1 â¡ ( 2 p + 1 â¢ p 2 â¢ ( 2 p - 1 ) â¢ BER target ) ] 2 when the number of bits is 2p and p is a positive integer; and SNR = ( 31 48 â¢ 2 2 â¢ p + 1 - 2 3 ) â¡ [ erfc - 1 â¡ ( 2 p + 1 â¢ â¢ ( 2 â¢ p + 1 ) 2 â¢ ( 2 p + 1 - 1 ) â¢ BER target ) ] 2 when the number of bits is 2p+1, p is a positive integer and pâ‰§2, wherein BER target is the predetermined target BER, wherein for an M-PSK modulation mode, the SNR lookup table is constructed with BER calculation formulas of SNR=[ erfc âˆ’1 (2BER target )] 2 when the number of bits is 1; SNR=2[ erfc âˆ’1 (2BER target )] 2 when the number of bits is 2; and SNR = [ erfc - 1 â¡ ( pBER target ) / sin â¡ ( Ï€ 2 p ) ] 2 when the number of bits is p, p is a positive integer and pâ‰§3, wherein BER target is the predetermined target BER.