Method and apparatus for near-optimal scaling of log-likelihood ratio (LLR) computation in turbo decoding for hybrid automatic repeat request (ARQ)

A base station apparatus, comprising:

• means for receiving data in a packet consisting of one or more subpackets depending on whether the packet belongs to one of a plurality of predetermined packet types;
• and
• means for scaling demodulated data symbols in the packet to compute scaled log-likelihood ratios for decoding the data, the means for scaling the demodulated data symbols comprising:
• means for determining a subpacket identification number for a most recently received subpacket of the packet, the subpacket identification number associated with a scale factor which results in a performance measure that is closest to an expected performance measure, and
• means for applying the scale factor to the demodulated data symbols to generate scaled log-likelihood ratios.

A computer readable medium having instructions stored thereon that, when executed, decode data in a packet comprising one or more subpackets, the computer readable medium comprising sets of instructions for:

• determining a subpacket identification number for a received subpacket of the packet, the subpacket identification number associated with a scale factor which results in a performance measure that is closest to an expected performance measure;
• applying the scale factor to demodulated data symbols in the packet to generate scaled log-likelihood ratios;
• and
• decoding the scaled log-likelihood ratios.

A base station apparatus comprising:

• an antenna coupled to a receiver, the receiver configured to receive data in a packet consisting of one or more subpackets depending on whether the packet belongs to one of a plurality of predetermined packet types;
• a demodulator configured to demodulate received data and generate demodulated data symbols;
• a log-likelihood ratio (LLR) computer configured to:
• determine a subject identification number for a most recently received subpacket of the packet, the subpacket identification number associated with a scale factor which results in a performance measure that is closest to an expected performance measure, and
• apply the scale factor to the demodulated data symbols to generate scaled log-likelihood ratios.

A wireless communication system comprising:

• an access terminal;
• a base station in communication with the access terminal, the base station comprising:
• an antenna coupled to a receiver, the receiver configured to receive data in a packet consisting of one or more subpackets transmitted by the access terminal depending on whether the packet belongs to one of a plurality of predetermined packet types;
• a demodulator configured to demodulate received data and generate demodulated data symbols;
• a log-likelihood ratio (LLR) computer configured to:
• determine a subpacket identification number for a most recently received subpacket of the packet, the subpacket identification number associated with a scale factor which results in a performance measure that is closest to an expected performance measure, and
• apply the scale factor to the demodulated data symbols to generate scaled log-likelihood ratios.