Method and apparatus for near-optimal scaling of log-likelihood ratio (LLR) computation in turbo decoding for hybrid automatic repeat request (ARQ)
First Claim
1. A method for decoding data in a packet comprising one or more subpackets, the method comprising:
- 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.
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Abstract
A method and an apparatus for scaling demodulated data symbols contained in a packet to generate scaled log-likelihood ratios for Turbo decoding are disclosed. A packet consists of one or more subpackets depending on the type of packet. Each subpacket is identified by a subpacket identification number. The payload size of the packet and the subpacket identification number may be determined by decoding a reverse rate indicator (RRI) channel. A scale factor which is associated with a specific subpacket identification number and a specific payload size results in a performance measure that is closest to an expected performance measure. The scale factor is used for scaling the demodulated data symbols to generate scaled log-likelihood ratios for Turbo decoding.
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Citations
67 Claims
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1. A method for decoding data in a packet comprising one or more subpackets, the method comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A base station apparatus, comprising:
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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. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. 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:
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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. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A base station apparatus comprising:
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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. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66)
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67. A wireless communication system comprising:
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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.
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Specification