A New Up Bound of Spacing Between Pilot Symbols over Fading Channels in PSAM Systems

This paper gives a new way to employ the second order characteristics of fading channels, i.e., the level crossing rate and average fading duration. The purpose of the paper is to define a new up bound of the spacing between pilot symbols by using level crossing rate and average fading duration to improve the spectral efficiency in pilot symbol assisted modulation systems. And find an up bound to make the system has both efficiency and reliability. It has also been proved that the new definition can be used as an adaptive adjustment of pilot symbols when the transmitter knows the channel state information in an adaptive system.