ECC awarded patent for Information Planar approximating method for computing the log-likelihood ratio optimal signal metric of each component code decoder in 8-PSK block coded modulation systems

Cleveland, OH - August 12, 1997 - ECC was awarded a patent for computing the signal metric for the least reliable bit, or "bottom code channel bit", in 8-PSK block coded modulation communication systems. A means of computing the signal metric for the "middle bit" is also developed. The optimum decoding of component codes in Block Coded Modulation (BCM) schemes requires the use of the Log-Likelihood Ratio (LLR) as the signal metric. The essence of the invention is a means of accurately approximating the computation of the LLR in a way which is simple to implement directly. The invention, the Log-Likelihood Ratio Planar Approximation (LLRPA), mathematically consists solely of planar equations with fixed point arithmetic that provides both an accurate estimate of the LLR and is easily realized in electronic hardware. The optimum decoding of component codes in Block Coded Modulation (BCM) schemes requires the use of the Log-Likelihood Ratio (LLR) as the signal metric.