Robust frequency burst detection algorithm for GSM/GPRS

GSM/GPRS uses a combination of FDMA and TDMA. A frequency correction burst (FCH burst) and synchronization burst are used in the acquisition phase of frequency and timing synchronization, respectively, by the mobile station (MS). A prior knowledge of timing is required for the MS to capture the FCH burst. A timing sync algorithm cannot be used to get timing information unless frequency sync is achieved. So there is it need to identify the time of occurrence of the FCH burst before timing acquisition is achieved. In this paper, we proposed a robust algorithm that exploits the properties of the FCH burst to identify its location accurately enough to perform frequency sync. The convergence property of an adaptive line enhancer (ALE) in the FCH burst is used for detection of the FCH burst and the divergence property of the ALE at FCH burst transition is used to identify the edges of the FCH burst. Some simulation results are illustrated to show the effectiveness of the proposed algorithm. The algorithm is robust enough to perform well even for large frequency mismatches between MS and base station and low SNRs. The algorithm is computationally efficient without sacrificing performance.