Research On The Channel Estimation And Signal Detection Technique Based On Approximate GMSK System

In wireless communication system, Gaussian Minimum Shift Keying (GMSK:Gaussian Minimum Shift Keying) signal has strictly constant envelope, which canprovide high frequency utilization efficiency and power efficiency, also can resist theinfluence of nonlinear, so GMSK system is of great significance. This article will giveGMSK signal a further approximation processing, which make some SNR estimationalgorithm of real-time can be applicated to GMSK system, and the complexity of thereceiver signal detection can be reduced.At first，this paper studied the signal to noise ratio estimation algorithm of linearapproximate GMSK, SVR, SNV, M2M4, ML real-time simulation algorithms arestudied,research results show that the estimate mean of the algorithm has obviousdeviation compared with true value in low signal-to-noise ratio (SNR); So for betterestimation performance under low signal-to-noise,SSME algorithm was studied, andalso analyzed the number of symbols and number of samples per symbol to the effect ofperformance.In signal detection, at first, the multi-branch fractional multi-bit differentialdetection technique with decision feedback is proposed,which is used in approximateGMSK system.This method is based on the combination of decision feedback techniqueand the multi-branch fractional multi-bit differential detection technique. Simulationresults and further analysis show that the new detection technique reduces theinter-symbol interference, which leads to the performance improvement. Then themethod of simplified orthogonal basis and truncated small eigenvalue method has beused for reducting the number of the matched filter in the receiving terminal, and thesetwo algorithms are used for the corresponding SCGMSK system,which can discoveredthat these two algorithms can greatly reduce the system complexity in the receivingterminal under the condition that the performance loss is very small.