A pilot symbol-aided technique used for digital signals in multipath environments

The paper proposes a pilot symbol-aided technique to reduce the effects of multipath fading on digital signals in mobile radio environments. A pilot symbol from a known sequence is multiplexed into the data symbols at regular intervals to form frames of symbols for transmission. Using the pilot symbols in two consecutive frames, the receiver is able to estimate and correct the fading distortion. The proposed technique uses a linear extrapolation approach that requires no storage of previous data symbols and introduces virtually zero delay to the received message. A series of computer-simulation tests has been carried out to assess the performance of the proposed technique on different signal constellations, including the 8 PSK, 16 PSK, 16 QAM and star-16 QAM signals, in the Rayleigh fading channels. The results have shown that significant improvements in bit-error rate performances of the systems can be achieved by the proposed technique