A new high performance turbo encoder scheme for bandwidth efficient modulation

In this paper we combine nonuniform signaling with the pragmatic binary turbo coded modulation environment. Our shaping method follows the technique proposed by Gallager (1968). This technique can be easily applied to any binary turbo or turbo-like code, including parallel, serial and low density parity check (LDPC) codes. The nonequiprobable letters are obtained by using a table that maps b-bits equiprobable input words onto nonequiprobable m-bits M-ary PAM (or equivalently M² QAM) symbols, at rates 2 and 3 bits/dim.