Citation
Abstract
Instead of using the criterion of maximum free distance, dp, or the maximum dy with minimizing a few first distance profiles, we searched short constraint length rate 1/N convolutional codes using a new criterion of minimizing required bit energy-to-noise density ratio, E,/N,, for a given value of desired bit error rate (BER), for the goodness of a code. The considered channel was binary antipodal signaling over additive white Gaussian noise and no quantization at the channel output. For the BER calculations, the transfer function bounding technique was used. Partial searches were performed using some known facts and a very useful new idea that ‘good codes generate good codes." That is, for a given constraint length K, good rate 1/(N + 1) codes can be found by extending the code generator matrices of good rate 1/N codes. The code search results are tabulated for 3 <K <7and2<N <8, For many pairs of K and N, the new codes are shown to save 0.1 to 0.4 dB in the required E/N, compared to previously reported codes. Additionally, the benefits of coding bandwidth expansion are confirmed with our new codes..
Details
- Volume
- 42-77
- Published
- May 15, 1984
- Pages
- 41–56
- File Size
- 831.5 KB