New MLSE receiver free from sample timing and input level controls

A new maximum likelihood sequence estimator (MLSE) receiver which is tolerant of both aberrations in sample timing and variations in amplitude is presented. In the proposed receiver, input signals are represented in polar coordinates, and fractionally sampled signals are fed to the MLSE. These two features make it possible to greatly reduce control mechanisms without performance degradation. The performance of the receiver is evaluated both in computer simulations and in experiments in US time division multiple access (TDMA) cellular environments, and it is shown that under conditions of 65-dB amplitude variations it successfully achieves less than 3% bit error rate (BER) without controlling either input level or sample timing