Because of non-negligible ISI due to the Gaussian filter and delay spread in the GSM system, an equalizer is required. In this letter, a joint sliding window channel estimation and timing adjustment method is proposed for maximum likelihood sequence equalizer. And also a smoothing algorithm is presented in order to improve the equalizer performance. This smoothing scheme utilizes a variant of LMS algorithm to tune the channel coefficient estimates. Simulation results show that the proposed scheme is adequate for channel estimation of the adaptive equalizer.

The frequency-offset estimation of a wireless asynchronous transfer mode (ATM) modem based on the orthogonal frequency division multiplexing (OFDM) is discussed. For burst synchronization operating under the time-division multiple access (TDMA) medium access control (MAC), an OFDM preamble using a multistage frequency-offset estimation technique is proposed and shown to have a good accuracy with a large estimation range. And also an averaged decision-directed channel estimation (ADDCE) technique suitable for burst data is proposed.

The frequency offset estimation is used to correct any frequency error of the local reference oscillator. In this letter, a frequency offset estimation algorithm utilizing the peak phase error detection and frequency offset smoother is proposed for burst data transmission. The basic idea of frequency offset estimator is to use a curve fitting method. The proposed peak phase error detection avoids a large phase error which yields a bad value for FOE. In order to control the AFC, frequency offset smoother by a simple filter is used. Simulation results show that the proposed algorithm is adequate for frequency offset estimation of burst data transmission.

A timing synchronization is required in the mobile station to determine the correct transmission timing of the mobile-to-base bursts. In this letter, a timing synchronization technique using the reliability check and smoothing algorithm is proposed for the GSM receiver. The reliability check scheme extends the usefulness of this algorithm into low SNR region. And also smoothing algorithm is carried out by a first-order filter with an asymmetric step size. Simulation results show that the proposed algorithm is adequate for timing recovery of GSM modem.

This letter is concerned with a new algorithm which can be used to design a time-domain equalizer (TEQ) for xDSL systems employing the discrete multitone (DMT) modulation. The proposed algorithm, derived by neglecting the terms which do not affect the performance of a DMT system in ARMA modeling, is shown to have a good performance compared with the previous TEQ algorithms even with a significantly lower computational complexity. In addition, the proposed algorithm does not require the channel impulse response or training sequence, since all processing is made only with the received data.