Method for allocating bits and power in multi-carrier communication system

A method of transmitting a data bit stream on a transmission system, the transmission system having a plurality of carriers and a target bit error rate, each carrier initially having a known transmit power, comprising the steps of:

• a. estimating a signal to noise ratio for each carrier for the known transmit power for each carrier;
• b. allocating a quantity of bits for each carrier so that a bit error rate is less than or equal to the target bit error rate for the estimated signal to noise ratio, wherein the quantity of bits is a whole number greater than or equal to zero;
• c. computing total excess power available for a current allocation of bits;
• d. computing excess power required by each carrier to carry additional bits;
• e. allocating at least a portion of the total excess power to at least one carrier on the basis of the computed excess power required by each carrier to carry additional bits;
• f. converting the data bit stream into a plurality of parallel bit streams based on the allocation of the total excess power;
• g. encoding the parallel bit streams;
• h. scaling the encoded parallel bit streams with a gain based on the allocation of the total excess power;
• and
• i. modulating the encoded and scaled parallel bit streams for transmission.

A transmission system having a plurality of carriers and a target bit error rate, each carrier initially having a nominal or known transmit power, comprising:

• a. means for converting a serial data stream into a plurality of parallel data streams, each parallel data stream having a bit rate;
• b. means for encoding the parallel data streams in a quadrature amplitude modulation points connected to the means for converting;
• c. means for scaling the encoded parallel data streams connected to the means for encoding;
• d. means for modulating the scaled encoded parallel data streams connected to the means for scaling;
• e. means for allocating the bit rate for each of the parallel data streams and for allocating power for the means for scaling, comprising:
• 1. means for estimating a signal to noise ratio for each carrier for the transmit power for each carrier;
• 2. means for allocating a quantity of bits for each carrier so that the bit error rate is less than or equal to the target bit error rate for the estimated signal to noise ratio, wherein the quantity of bits is a whole number greater than or equal to zero;
• 3. means for computing total excess power available for a current allocation of bits;
• 4. means for computing additional power required by each carrier to carry additional bits;
• and
• 5. means for allocating at least a portion of the total excess power to at least one carrier in response to the means for computing total excess power and the means for computing additional power required by each carrier to carry additional bits;
• f. a channel connected to the means for modulating;
• g. means for demodulating, connected to the channel;
• h. means for applying inverse scaling connected to the means for demodulating;
• i. means for decoding quadrature amplitude modulation points connected to the means for inverse scaling;
• and
• j. means for converting a plurality of parallel data streams into a serial data stream connected to the means for decoding quadrature amplitude modulation points.