Optimal designs for linear and nonlinear precoders and decoders

Precoding and decoding techniques have been widely used to shape the transmitted signaland to introduce the redundancy in order to eliminate the intersymbol interference (ISI). This thesis focuses on designing linear and DFE-based nonlinear precoders and decoders for the sake of improving the performance of transmission information rate and bit error rate. For linear scheme, we introduce a new criterion named weighted information rate criterion that generalizes our linear precoder and decoder optimal designs. We can obtain maximum information rate design, minimum mean-squared error design and QoS based design when we choose different corresponding weight matrices. For DFE-based nonlinear scheme, we use Lagrangian optimizing method to make the eigenvectors of the precoder matrix match to the eigenvectors of the circulant channel matrix to maximize the information rate and use discrete fourier transform matrix and an MMSE decoder to minimize the bit error rate. We manage to maximize the information rate and to minimize the bit error rate at the same time. The simulation results of linear weighted information rate criterion show that we can achieve different optimal designs by choosing different weight matrices. For our nonlinear precoder and decoder designs, the improvement of information rate is considerable and the bit error rate performances of our MBER-DFE design are always better than the MMSE-DFEdesign under different channel conditions.

Author dc:creator

• LI NAN

• Precoder,Decoder,Inter-symbol Interference,Weight Matrix,Lagrangian Method, Discrete Fourier Transform Matrix.