BCE and PCE Performance

In this chapter we identify the structural characteristics of Binary Convolutional Encoders (BCE’s) and Parallel Concatenated Encoders (PCE’s) that determine their error control performance. It will be shown that one important factor for PCE performance is the spar-sity of codewords at weights near the free Hamming distance. Another is the manner in which information sequences are mapped to code or parity sequences. An analytic framework is provided for performance analyses over the Additive White Gaussian Noise (AWGN) channel. This framework can only provide performance bounds — an exact performance analysis has not yet been devised. The bounds are useful, however, both for conceptual and design purposes. For example, the bounds indicate that the size of the PCE interleaver is an important contributor to performance when the component encoders are systematic IIR BCE’s. This inference is readily verified through simulations.