  In this paper, we provide a performance analysis of a new class of serial
concatenated convolutional codes (SCCC) where the inner encoder can be
punctured beyond the unitary rate. The puncturing of the inner encoder is not
limited to inner coded bits, but extended to systematic bits. Moreover, it is
split into two different puncturings, in correspondence with inner code
systematic bits and parity bits. We derive the analytical upper bounds to the
error probability of this particular code structure and address suitable design
guidelines for the inner code puncturing patterns. We show that the percentile
of systematic and parity bits to be deleted strongly depends on the SNR region
of interest. In particular, to lower the error floor it is advantageous to put
more puncturing on inner systematic bits. Furthermore, we show that puncturing
of inner systematic bits should be interleaver dependent. Based on these
considerations, we derive design guidelines to obtain well-performing
rate-compatible SCCC families. Throughout the paper, the performance of the
proposed codes are compared with analytical bounds, and with the performance of
PCCC and SCCC proposed in the literature.
