A severely punctured convolutional code-its performance and structure

Severely punctured versions of the well-known rate-1/2, constraint-length-seven convolutional code are considered. Severely punctured means that exactly half of the data normally transmitted is deleted, specifically, the entire output of one parity circuit or the other. Redundancy is conveyed only by the code tail. It is shown that, for maximum likelihood decoding of short to moderately long messages, significant coding gains can be achieved, 2 to 3.8 dB. Both simulation and analytical results are given. It is also shown that less severely punctured codes have minimum distance two, and, for one of the generators, the punctured codes are cyclic for certain message lengths