The effect and influence of the slotted pilot scheme on the mobile CDMA systems

Phase-shift keying (PSK) is an attractive modulation scheme for mobile radio due to its high power efficiency at moderate bit error rates. However, an appropriate pilot signal is required to achieve reliable transmission with coherent modulation on fading channels in code division multiple access (CDMA) technology. In this paper, a pilot-symbol-assisted modulation scheme is investigated. The choice of the slot (including pilot symbols and data symbols) length and pilot spacing is discussed. Since the Doppler spread is related to vehicle speed and carrier frequency, the slot length should be decided by the channel coherent time in order to maintain the required channel quality. It is shown that the higher the vehicle speed, the shorter the slot should be. The spacing of the pilot should be satisfied, also due to the vehicle speed