Method and apparatus for performing rate determination using orthogonal rate-dependent walsh covering codes

A rate determination apparatus adapted for use in a communication system having a communication link, comprising:

• a) means for covering code symbols with a selected one of a plurality of rate-dependent orthogonal Walsh covering codes, each such Walsh covering code being associated with a unique data rate;
• b) means, operatively connected to the covering means, for transmitting the covered code symbols over the communication link at a selected available data rate associated with the selected one Walsh covering code;
• c) means, responsive to the transmitting means, for deriving rate dependent metrics based upon the transmitted code symbols;
• and
• d) means, responsive to the deriving means, for determining the selected available data rate based upon the metrics derived.

A system for performing rate determination in a communication system having a communication link, wherein code symbols are transmitted over the communication link at a selected one of a plurality of available data rates, comprising:

• a) a symbol repetition and encoding block wherein code symbols are repeated and covered with a selected one of a plurality rate-dependent orthogonal Walsh covering codes, each such Walsh covering code being associated with a unique data rate;
• b) means, operatively connected to the symbol repetition and encoding block, for transmitting the covered code symbols over the communication link at the selected available data rate associated with the selected one Walsh covering code;
• c) a plurality of soft combiners in wireless communication with the transmitting means, wherein each soft combiner has a respective data rate associated thereto, and wherein the soft combiners output de-interleaved combined code symbol sequences;
• d) a plurality of Viterbi decoder and rate re-encoder pairs operatively connected to respective associated soft combiners, wherein the rate re-encoders output re-encoded code symbols;
• e) a plurality of symbol error rate (SER) blocks having a first input that is operatively connected to a respective associated soft combiner and having a second input that is operatively connected to a respective associated re-encoder output, wherein each SER estimator generates an SER metric by comparing, on a symbol-by-symbol basis, code symbols generated by its associated soft combiner with code symbols generated its associated re-encoder;
• and
• f) means, responsive to the SER estimators, for determining the selected available data rate based upon the SER metrics generated by the SER estimators.

A system for performing rate determination in a communication system having a communication link, wherein code symbols are transmitted over the communication link at a selected one of a plurality of available data rates, comprising:

• a) a symbol repetition and encoding block wherein code symbols are repeated and covered with a selected one of a plurality rate-dependent orthogonal Walsh covering codes, each such Walsh covering code being associated with a unique data rate;
• b) means, operatively connected to the symbol repetition and encoding block, for transmitting the covered code symbols over the communication link at the selected available data rate associated with the selected one Walsh covering code;
• c) a plurality of soft combiners in wireless communication with the transmitting means, wherein each soft combiner has a respective data rate associated thereto, and wherein the soft combiners output de-interleaved combined code symbol sequences;
• d) a plurality of Viterbi decoder and rate re-encoder pairs operatively connected to respective associated soft combiners, wherein the rate re-encoders output re-encoded code symbols;
• e) a plurality of energy metric calculators having a first input that is operatively connected to a respective associated soft combiner and having a second input that is operatively connected to a respective associated re-encoder output, wherein each energy metric calculator generates an energy metric by multiplying, on a symbol-by-symbol basis, code symbols generated by its associated soft combiner and code symbols generated by its associated re-encoder;
• and
• f) means, responsive to the energy metric calculators, for determining the selected available data rate based upon the energy metrics generated by the energy metric calculators.

A computer program executable on a general purpose computing device, wherein the program is capable of determining data rates of code symbols transmitted over a communication link, wherein the code symbols are repeated a pre-determined number of times per symbol depending upon the data rate used for transmission, and wherein the code symbols are transmitted at a selected one of a plurality of available data rates, comprising:

• a) a first set of instructions for covering the code symbols with a selected one of a plurality of rate-dependent orthogonal Walsh cover codes, each such Walsh covering code being associated with a unique data rate;
• b) a second set of instructions for deriving rate-dependent metrics based upon the covered code symbols;
• and
• c) a third set of instructions for determining the selected transmission data rate based upon the derived rate-dependent metrics.