| 摘要 |
Received signals are decoded based on a coupling between bits of the received signals introduced by the channel over which the signal is transmitted or by the transmitter which transmitted the signals. For example, in a higher-order modulation scheme, such as 8-PSK, individual bits grouped in a given symbol are generally coupled rather than fully independent. Accordingly, decoding information on a first one of the bits processed through a forward error correction decoder may be used to adjust the soft information from a demodulator for one or more of the other bits contained in the same symbol for use in processing those bits through the forward error correction decoder. Particularly where interleaving is utilized, a first bit may be processed through the decoder before the soft information on another of the bits is needed, thereby allowing an intermediate decision soft value for the first bit to be used in generating the input value to the decoder for the subsequent bit. Alternatively, a multi-pass process may be utilized which may allow all of the bits to be decoded utilizing soft information from the first decoding pass to affect the input to the decoder during the second pass for coupled bits such as those transmitted in a common symbol. |
