Performance evaluation of a G.dmt-compliant digital subscriber line system

A method of selecting forward error correction parameters in a channel having a plurality of subchannels in a multicarrier communications system, comprising:

• determining a signal-to-noise ratio representing a subset of the subchannels to provide said representative performance measurement;
• storing, in a table, the number (s) of discrete multi-tone symbols in a forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, and the number of subchannels associated with the signal-to-noise ratio, and a net coding gain for different values of s, z, signal-to-noise ratios and numbers of subchannels;
• and
• selecting forward error correction parameters of the channel based on the net coding gain by applying an approximation to a subset of values in the table.

A method of selecting forward error correction parameters in a channel having a plurality of subchannels in a multicarrier communications system, comprising:

• determining a signal-to-noise ratio representing a subset of the subchannels to provide said representative performance measurement;
• storing, in a table, the number (s) of discrete multi-tone symbols in a forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, the maximum number of transmissions (k) and the number of subchannels associated with the signal-to-noise ratio, and a net coding gain for different values of s, z, signal-to-noise ratios and numbers of subchannels;
• and
• selecting forward error correction parameters of the channel based on the net coding gain by applying an approximation to a subset of values in the table.

A method of determining an optimum bit load per subchannel in a multicarrier system with forward error correction, comprising:

• computing one or more values of a maximum number of symbol errors that can be corrected t, and a number of symbols in the information field K to determine the optimum bit load per subchannel in accordance with the following relationship:
• 102 1 - ( 1 - W ⁡ ( s , z , K ) ⁢ ϵ 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 ) ) , and × [AutoLeftMatch] [ 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 + ρ ⁢ ⁢ s + sz ) Γ ⁡ ( K + ρ ⁢ ⁢ s + 0.5 · sz ) ⁢ Γ ⁡ ( 0.5 · sz + 1 ) ] - 1 / ( 0 ⁢ ⁢ 5 · sz + 1 ) ⁢ ⁢ wherein ⁢ ⁢ ω ⁡ ( b ) = 4 2 ⁢ b + 3 ,
• Θ(x)=(x−1)!,
• s represents a number of discrete-multi-tone symbols in a frame, z represents a number of control code symbols per discrete-multi-tone symbol, b represents a number of bit positions of a quadrature-amplitude-modulation symbol, ω(b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, γeff represents an effective signal-to-noise ratio, and ρ represents a number of overhead symbols per discrete multi-tone symbol;
• and
• selecting the maximum number of symbol errors that can be corrected t, and the number of symbols in the information field K such that the uncoded bit error rate pb that produces a symbol error rate that is less than or equal to the target symbol error rate is increased.

An apparatus for determining an optimum bit load per subchannel in a multicarrier system with forward error correction, comprising:

• means for computing one or more values of a maximum number of symbol errors that can be corrected t, and a number of symbols in the information field K to determine the optimum bit load per subchannel in accordance with the following relationship:
• 105 1 - ( 1 - W ⁡ ( s , z , K ) ⁢ ϵ 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 ) ) , and × [AutoLeftMatch] [ 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 ) ⁢ ⁢ wherein ⁢ ⁢ ω ⁡ ( b ) = 4 2 ⁢ b + 3 ,
• Γ(x)=(x−1)!,
• s represents a number of discrete-multi-tone symbols in a frame, z represents a number of control code symbols per discrete-multi-tone symbol, b represents a number of bit positions of a quadrature-amplitude-modulation symbol, ω(b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, γeff represents an effective signal-to-noise ratio;
• and
• means for selecting the maximum number of symbol errors that can be corrected t, and the number of symbols in the information field K such that the uncoded bit error rate pb that produces a symbol error rate that is less than or equal to the target symbol error rate is increased.

An apparatus for selecting forward error correction parameters in a channel having a plurality of subchannels in a multicarrier communications system, comprising:

• means for determining a signal-to-noise ratio representing a subset of the subchannels to provide said representative performance measurement;
• means for storing, in a table, the number (s) of discrete multi-tone symbols in a forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, and the number of subchannels associated with the signal-to-noise ratio, and a net coding gain for different values of s, z, signal-to-noise ratios and numbers of subchannels;
• and
• means for selecting forward error correction parameters of the channel based on the net coding gain by applying an approximation to a subset of values in the table.

An apparatus for selecting forward error correction parameters in a channel having a plurality of subchannels in a multicarrier communications system, comprising:

• means for determining a signal-to-noise ratio representing a subset of the subchannels to provide said representative performance measurement;
• means for storing, in a table, the number (s) of discrete multi-tone symbols in a forward-error-correction frame, the number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, the maximum number of transmissions (k) and the number of subchannels associated with the signal-to-noise ratio, and a net coding gain for different values of s, z, signal-to-noise ratios and numbers of subchannels;
• and
• means for selecting forward error correction parameters of the channel based on the net coding gain by applying an approximation to a subset of values in the table.

An apparatus for determining an optimum bit load per subchannel in a multicarrier system with forward error correction, comprising:

• means for computing one or more values of a maximum number of symbol errors that can be corrected t, and a number of symbols in the information field K to determine the optimum bit load per subchannel in accordance with the following relationship:
• 108 1 - ( 1 - W ⁡ ( s , z , K ) ⁢ ϵ 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 ) ) , and × [AutoLeftMatch] [ 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 + ρ ⁢ ⁢ s + sz ) Γ ⁡ ( K + ρ ⁢ ⁢ s + 0.5 · sz ) ⁢ Γ ⁡ ( 0.5 · sz + 1 ) ] - 1 / ( 0 ⁢ ⁢ 5 ⁢ ⁢ sz + 1 ) ⁢ ⁢ wherein ⁢ ⁢ ω ⁡ ( b ) = 4 2 ⁢ b + 3 ,
• Γ(x)=(x−1)!,
• s represents a number of discrete-multi-tone symbols in a frame, z represents a number of control code symbols per discrete-multi-tone symbol, b represents a number of bit positions of a quadrature-amplitude-modulation symbol, ω(b) represents an average fraction of erroneous bits in an erroneous b-sized quadrature-amplitude-modulation symbol, γeff represents an effective signal-to-noise ratio, and ρ represents a number of overhead symbols per discrete multi-tone symbol;
• and
• means for selecting the maximum number of symbol errors that can be corrected t, and the number of symbols in the information field K such that the uncoded bit error rate pb that produces a symbol error rate that is less than or equal to the target symbol error rate is increased.