Patent ID: 8184745

Claim:
A receiver that receives a radio frequency (RF) signal from a communication link, the RF signal including a stream of transmitted symbols modulated onto a carrier, each of the transmitted symbols being selected from a constellation of base symbols to represent a plurality of encoded data bits, the receiver comprising: a radio frequency (RF) module operable to produce a stream of received symbols derived from the stream of transmitted symbols included within the RF signal; a demodulator operable to receive the stream of receive symbols and to produce a stream of soft bits derived from the stream of received symbols; a memory device operable to store information related to a plurality of base symbols in the constellation, the information including a nearest-neighbor look-up table and a polarity look-up table for each data bit represented by a base symbol in the constellation; and a channel decoder operable to receive the stream of soft bits from the demodulator and to produce a stream of decoded data bits derived from the stream of soft bits, wherein for each received symbol in the stream of received symbols the demodulator: determines which of the plurality of base symbols in the constellation is a closest symbol to the received symbol, the closest symbol including a plurality of first data bits; calculates a first distance between the received symbol and the closest symbol; and for each first data bit included within the closest symbol, the demodulator: identifies a nearest neighbor symbol from the nearest-neighbor look-up table stored in the memory device; calculates a second distance between the received symbol and the nearest-neighbor symbol; subtracts the first distance from the second distance to produce a first soft bit associated with the first data bit; and applies a polarity value from the polarity look-up table stored in the memory device to the first soft bit, prior to including the first soft bit into the stream of soft bits to be delivered to the channel decoder.