Simulation and Implementation of SNR Measurement processor for Adaptive Communication Systems

Abstract

The measurement of SNR is the backbone of the adaptive modulation (AM) system to select the type of modulation techniques according to the data rate required. In this paper simulation, implementation and evaluation of SNR for selectable adaptive modulation are given. BPSK, QPSK and QAM modulation techniques are used in this work. The main units of this system are BPSK modem, QPSK modem, 8QAM modem, inserting pilot channel and SNR measurement channel. Separation of the noise from received signal is required to find SNR. Experimental results show difference between the set value and measured value of SNR in the presence of AWGN for BPSK modem and QPSK modem. Losses by using pilot symbol assisted modulation (PSAM) (±0.85) dB in the presence of AWGN for QPSK and MQAM. Experimental result proved also the pilot technique is better than data and using the pilot technique is independent on the type of modulation and the results show that there is coincidence between transmitted and received data with a delay of (0.3-0.4µs). However, the combination of MATLAB (Simulink and M-file) and Simulink HDL Coder provides flexible capabilities for analysis, design, simulation, implementation and verification.