In this paper we present improved techniques for transmitting M-PSK signals in mobile radio environments. Conventionally an optimal linear combination of the observable fading at the pilot symbols has been used as estimations of all other fading. Recently, an improved technique was proposed by the authors which employs not only the pilot symbols but also the previously estimated fading values on data symbols to extract more information on fading channels. In this paper we present new methods by further improving the above method invented by the authors. The present methods utilize, instead of the estimated fading values on data symbols, the demodulator output normalized by the decided (decoded) data symbols to estimate the fading values in the current frame. We also show by computer simulations for BPSK system that the proposed estimation methods provide better performance than those of the conventional methods.

In this paper the conventional symbol-aided estimation methods are extended to use not only the known pilot symbols but also the previously estimated fading values to extract more information on fading channels. The proposed estimation method is evaluated using theoretical analyses. Recursive formulae are derived for calculating the mean square estimation errors, which are then used to calculate the BER performance of a BPSK system employing the proposed fading estimation method. The results show strong BER performance of the proposed system in the region of high signal to noise ratio under fast fading compared to that of the conventional system. Moreover, the proposed system still sustains its performance under mismatched conditions, where the conventional system degrades exhibiting error floors. Finally the theoretical results are verified by using computer simulations.

This paper presents a technique to transmit 16QAM signals in mobile radio environments by using extended symbol-aided estimation (ESAE) method for compensating the multipath fading effect. The main results of this paper are the symbol error rate (SER) performance analyses for BPSK and 16QAM systems using the proposed estimation method under Rician fading. The analytical results demonstrate better performance of the proposed systems compared with those of the conventional systems under fast and severe fading, especially in the region of high signal to noise ratio.