Schroeder sequences for time dispersive frequency selective channel estimation using DFT and Least Sum of Squared Errors methods

Digital communication systems operating on time varying depressive channels often employ a signalling format in which customer data are organized in blocks proceeded by a known sequence. The training sequence at the beginning of each block is used to train an adaptive equalizer and/or data sequence detector to combat intersymbol interference (ISI). This paper addresses the problem of comparing the Schroeder sequences as a very close to optimal training sequence for channel estimation (start up) in communication systems over time dispersive frequency selective channels. Schroeder sequences of comparable lengths to the designed -computer searched- sequences demonstrated a tight performance for both the optimal sequences designed using Discrete Fourier Transform (DFT) technique and the sequences designed via Least Sum of Squared Errors (LSSE) channel estimation. Performance results are provided for Schroeder sequences of lengths 36 and 28 (the choice of 28 is driven by the fact that channel estimation sequences for GSM system are of length 28).