Rate selection with margin sharing

An apparatus in a communication system including a plurality of transmission channels, comprising:

• means for obtaining a signal-to-noise ratio (SNR) estimates for each one of a plurality of data streams for transmission of the data stream over one of the transmission channels;
• means for selecting a rate for each of the plurality of data streams based on the SNR estimates for that data stream;
• means for determining an SNR margin for each data stream based on the SNR estimate for that data stream and a required SNR for the rate selected for that data stream, and
• means for adjusting the selected rates for the data streams so that at least one data stream has its SNR margin below a threshold, each remaining data stream has its SNR margin above the threshold, and a total SNR margin for all of the data streams is above a total SNR margin threshold.

A processor readable media having stored therein processor-usable instructions for a processor, wherein said instructions when executed by the processor cause the processor to:

• obtain a signal-to-noise ratio (SNR) estimate for each one of a plurality of data streams for transmission of the data stream over one of the transmission channels;
• select a rate for each data stream based on the SNR estimate for that data stream;
• determine an SNR margin for each data stream based on the SNR estimate for that data stream and a required SNR for the rate selected for that data stream, and
• adjust the selected rates for the plurality of data streams so that at least one data stream has its SNR margin below a threshold, each remaining data stream has its SNR margins above the threshold, and a total SNR margin for all of the data streams is above a total SNR margin threshold.