  In this paper, we study polar codes from a practical point of view. In
particular, we study concatenated polar codes and rate-compatible polar codes.
First, we propose a concatenation scheme including polar codes and Low-Density
Parity-Check (LDPC) codes. We will show that our proposed scheme outperforms
conventional concatenation schemes formed by LDPC and Reed-Solomon (RS) codes.
We then study two rate-compatible coding schemes using polar codes. We will see
that polar codes can be designed as universally capacity achieving
rate-compatible codes over a set of physically degraded channels. We also study
the effect of puncturing on polar codes to design rate-compatible codes.
