A P-BRO interleaver and a method for optimizing parameters according to an interleaver size for the P-BRO interleaver. The P-BRO interleaver sequentially, by columns, arranges an input data stream of size N in a matrix having 2.sup.m rows and (J-1) columns, and R rows in a Jth column, P-BRO interleaves the arranged data, and reads the interleaved data by rows.