ON SAMPLING RATE, ANALOG PREFILTERING, AND SUFFICIENT STATISTICS FOR DIGITAL RECEIVERS

In this paper we consider the joint sequence estimation, timing and ph ase recovery for linear modulation. The paper differs from the classic al ones in the sense that time-discrete algorithms suitable for fully digital receivers are discussed. Sufficient conditions are given such that the signal samples represent sufficient statistics. These conditi ons involve signal bandwidth, sampling/symbol rate and the analog pref ilter characteristics. It is shown that the sampling rate need not be an exact multiple of the symbol rate, i.e., the samples can be taken f rom a free-running oscillator. All subsequent signal processing operat ions in the receiver then operate with the clock of this free-running oscillator. Timing recovery is then performed by a time-variant linear digital interpolator and a decimator. Carrier recovery and sequence e stimation are performed at an average rate of one symbol per sample. T he digital matched filter for this case is derived for an arbitrary co lored noise spectrum.