  It has been observed that particular rate-1/2 partially systematic parallel
concatenated convolutional codes (PCCCs) can achieve a lower error floor than
that of their rate-1/3 parent codes. Nevertheless, good puncturing patterns can
only be identified by means of an exhaustive search, whilst convergence towards
low bit error probabilities can be problematic when the systematic output of a
rate-1/2 partially systematic PCCC is heavily punctured. In this paper, we
present and study a family of rate-1/2 partially systematic PCCCs, which we
call pseudo-randomly punctured codes. We evaluate their bit error rate
performance and we show that they always yield a lower error floor than that of
their rate-1/3 parent codes. Furthermore, we compare analytic results to
simulations and we demonstrate that their performance converges towards the
error floor region, owning to the moderate puncturing of their systematic
output. Consequently, we propose pseudo-random puncturing as a means of
improving the bandwidth efficiency of a PCCC and simultaneously lowering its
error floor.
