Patent ID: 7110467

Claim:
A method of determining an optimum bit load per subehannel in a multicarrier system with forward error correction, comprising: computing one or more values of a number of bit positions b of a quadrature- amplitude-modulation symbol, based on one or more values of a number of symbols in an information field K, and one or more values of a number of control code symbols per discrete-multi-tone symbol z, to provide one or more determined values of b, in accordance with the following relationship: 1 - ( 1 - W ⁡ ( s , z , K ) ⁢ ɛ S 1 0.5 · sz + 1 ) 1 / α = ω ⁡ ( b ⁡ ( γ eff , s , z ) ) ⁢ ( 1 - 2 - b ⁡ ( γ eff , s , z ) / 2 ) ⁢ erfc ⁡ ( 3 · 10 γ eff / 10 / ( 2 b ⁡ ( γ eff , s , z ) + 1 - 2 ) ) , × [ 2 - ( 1 - 2 - b ⁡ ( γ eff , s , z ) / 2 ) ⁢ erfc ⁡ ( 3 · 10 γ eff / 10 / ( 2 b ⁡ ( γ eff , s , z ) + 1 - 2 ) ) ] ⁢ ⁢ W ⁡ ( s , z , K ) = [ Γ ⁡ ( K + s + sz ) Γ ⁡ ( K + s + 0.5 · sz ) ⁢ Γ ⁡ ( 0.5 · sz + 1 ) ] - 1 / ( 0.5 · sz + 1 ) ⁢ ⁢ ⁢ ω ⁡ ( b ) = 4 2 ⁢ b + 3 , Γ( x )=( x− 1)!, and b ⁡ ( γ eff , s , z ) = α sn eff ⁢ ( K + ρ ⁢ ⁢ s + zs ) s represents a number of discrete-multi-tone symbols in a frame, ε s represents a symbol error rate, α represents the size of a code symbol, ρ represents a framing mode index, ω(b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, γ eff represents an effective signal-to-noise ratio, and n eff represents an effective number of subchannels; and selecting the value of K and the value of z which provides a maximum number of bit positions based on the one or more determined values of b.