These weights depend on where the data symbol is
within the time slot.
As far as interpolation goes, various techniques exist such as linear, cubic-spline, polynomial
based, and so on. For the fast time varying examples discussed we have found the linear interpolator
to perform the worst and a polynomial based interpolator to perform the best.
A last point necessary to mention is that PSAM is a member of a more general family called pilot
aided modulation (PAM). We have presented a solution using time division multiplexed (TDM) pilot
symbols, solutions also exist for Frequency Division Multiplexing (FDM) pilot tones and lastly CDM
pilot channels. We would like to briefly discuss the CDM solution and provide more details in later
chapter that discusses WCDMA. The general idea is to transmit a continuous pilot signal that would
be used to coherently demodulate the data signal [25]. This is also applicable to Orthogonal
Frequency Division Multiplexing (OFDM)-based waveforms, where pilot symbols are generally time
and frequency multiplexed into the transmitted OFDM symbol.
4.2.4 Multiple Bit Observation (MBO) of MSK??”Coherent Detection
In this section we will build upon the assumption that carrier recovery has been performed.
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