NEW DQPSK SIMULTANEOUS CARRIER AND BIT-TIMING RECOVERY COHERENT DEMODULATOR FOR WIRELESS BROAD-BAND COMMUNICATION-SYSTEMS

This paper proposes a differentially-coded-quadrature-phase-shift-keyi ng (DQPSK) coherent demodulator using a new simultaneous carrier and b it-timing recovery scheme (SCBR). The new DQPSK SCBR (DSCBR) scheme wo rks with a frequently used preamble, whose baseband signal alternates between two diagonal decision points, for example, a repeated bit-seri es of ''1001.'' With the DSCBR scheme, the proposed demodulator achiev es a significantly agile carrier and bit-timing recovery using an open -loop approach with a one-part preamble. To illustrate this, a preambl e of 8 symbols is applicable with the E-b/N-o degradation from the the ory over AWGN of 0.2 dB. It is also shown that the proposed demodulato r achieves an improvement in the required E-b/N-o of more than 2 dB ov er differential detection over Ricean fading communication channels. T he channels are modeled for wireless broadband communication systems w ith directional antennas or line oi sight (LOS) paths. This paper conc ludes that the proposed demodulator is a strong candidate for receiver s in wireless broadband communication systems.