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The modified structure of a Digital Phase Locked Loop (DPLL) based systems for dealing with Nakagami-m fading is proposed here. The emphasis of the work is to generate input signal under various fading conditions with certain modulation transmitted through Nakagami-m channels and to evaluate the performance of the proposed DPLL in terms of Bit Error Rate (BER). Statistical characteristics of the faded input signal have been evaluated in terms of Probability Distribution Function (PDF), Level Crossing Rate (LCR) and Average Fade Duration (AFD). A sixth order Least Square Polynomial Fitting (LSPF) block and Roots Approxiator (RA) for better phase-frequency detection have been implemented as a replacement of Phase Frequency Detector (PFD) and Loop Filter (LF) of a traditional DPLL, which has helped to attain optimum performance of DPLL. The results of simulation of the proposed DPLL with Nakagami -m fading and QPSK modulation shows that the proposed method provides better performance than existing systems of similar type. Keywordsdigital phase locked loop, numerically controlled oscillator, nakagami -m fading channels, least square polynomial fitting filter, level crossing rate and average fade duration.

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