Dual stage RSSI handoff trigger

摘要

An appropriate handoff trigger is determined in a cellular system by maintaining both a long term representation of the received signal strength and a short term measurement of the current signal strength. The long term representation is used as the initial trigger for a handoff condition. The averaging process removes the effects of short term fades in the signal that may cause a premature handoff decision due to these fluctuations. This initial trigger is then qualified by examining the short term current, value of the signal. The actual handoff trigger is only realized when both values indicate that the handoff threshold has been exceeded. This approach eliminates the occurrence of false handoff triggers caused by the historical bias that may exist from the long term averaging process. The short term signal strengths value is reported as the mobile station's signal for comparisons to the signal strength measured on the adjacent cells. Since this value represents the current measure of the signal, it provides a truer comparison with the current measurements made on the adjacent cells, and virtually eliminates delayed handoff realizations due to the long term average historical bias.