The effects of symbol rate offset on the BER performance of 16QAM signals

In non-cooperative communication we need to estimate of symbol rate blindly. Hence, it is necessary to correct symbol rate offset properly and estimate its effects on the receiving performance. In the paper, the symbol timing recovery loop using an acquisition-aiding technique (that is, adaptively adjusting loop bandwidth) can capture symbol rate offset of 1% with the help of the lock detector for 16 QAM signals. We analyze and simulate the effects for symbol rate offset of plusmn0.5% and plusmn1% on bit error rate (BER) performance over an additive white Gaussian noise (AWGN). The results show that under the same BER the real-time demodulation loss is less than 0.5 dB compared to the theoretical value. In addition, an out-of-lock detector is proposed. Together with the lock detector, the out-of-lock detector can ensure the symbol timing recovery loop provide good steady performance and relatively fast convergence rate by adaptively adjusting loop bandwidth.