CODE-AIDED TIMING SYNCHRONIZATION FOR MULTI-H CPM AT LOW SIGNAL-TO-NOISE RATIO

Abstract

In order to solve the problem of timing synchronization at low signal-to-noise ratio(SNR) for Multi-h CPM, a code-aided early-late loop(ELL) algorithm is proposed. The algorithm is based on the iterative detection of serially concatenated Multi-h CPM with convolutional codes. The ELL timing estimator based on sequence detection is extended to the maximum-logarithmic maximum a posteriori (max-log MAP) detection. By using the information updated by iterative detection, the timing accuracy of multi-h CPM can be improved at low SNR. The simulation results show that, even when the bit signal-to-noise ratio (Eb/No) is as low as 3dB~5dB, the estimating variance of the proposed synchronization can be close to the Cramer Rao bound(MCRB) of ARTM CPM. After this timing synchronizing, the detection performance of the 10th iteration is only 0.03dB loss compared with the performance with ideal synchronization.