Interleaving of data symbols comprises permuting rows and columns of a matrix of N.sub.r rows and N.sub.c columns, in which data symbols to be interleaved are represented row by row, in accordance with:

          Row Permutation        I.sub.r (k) = [.alpha..sub.r k + f.sub.c
     (l)]modN.sub.r
          Column Permutation     I.sub.c (l) = [.alpha..sub.c l + f.sub.r
     (k)]modN.sub.c

where I.sub.r (k) represents a data symbol with a row index k, k is an integer from 1 to N.sub.r, .alpha..sub.r is an integer, f.sub.c (l) is a non-zero function of a column index l, l is an integer from l to N.sub.c, I.sub.c (l) represents a data symbol with the column index 1, .alpha..sub.c is an integer, f.sub.r (k) is zero or a function of the row index k, and modN.sub.r and modN.sub.c represent modulo-N.sub.r and modulo-N.sub.c arithmetic respectively, interleaved data symbols being derived from the matrix column by column. A data interleaver comprises a memory for sequentially storing data symbols to be interleaved and a relatively simple circuit for determining read addresses for the interleaved data symbols. the data interleaver is particularly suited for channel interleaving in a 3rd generation CDMA wireless communications system.