| Summary: | 碩士 === 元智大學 === 電機工程學系 === 91 === For wireless communication, due to finite bandwidth and obtaining an efficiently service, it is important to increase the channel reuse ratio (CRR), thus an available and efficient handoff algorithm should be developed. In this thesis, we proposed a hybrid handoff algorithm for wireless communication systems using Grey prediction and fuzzy decision system (GPFD). The GPFD method composed of grey prediction scheme and fuzzy decision system. The grey predictor is used to predict the RSSI (Received Signal Strength Indication) value for the inputs of fuzzy decision system. Thus, fuzzy decision system calculates the so-called handoff factor (HF) and compares with the handoff factor threshold (HFT) to make the decision. Our decision is based on effice of hysteresis and due to reduce delayed handoff. They are BS’s RSSI drop fastly and less than remote BS switch to remote BS, and local BS’s RSSI great than remote BS then come back. The GPFD has high prediction accuracy, on-line, and robustness of decision, which results good performance even the so-called Manhattan corner effect occur (causes the received signal level to drop). Several simulation results and comparisons show the effectiveness of GPFD method.
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