DIVERSITY RECEPTION METHOD IN MOBILE COMMUNICATION SYSTEM

摘要

PURPOSE: To improve a noise figure for the entire reception system by increasing number of diversity branches without increasing-number of directivity antennas so as to improve the reception sensitivity. CONSTITUTION: The system uses a 4-input 4-output synthesis distribution phase shifter 30 configured in such a way that four output signals are a sum of shifting phases of four input signals and an output signal different based on a difference of phases of each input is obtained at each output. Then reception signals by four 180 deg. directivity antennas 21-24 whose maximum directivity differs from each other by 90 deg. each are given to the synthesis distribution phase shifter 30 to obtain signals equivalent to reception signals by four omnidirectional antennas. The reception signals are given to receivers 71-74, where the signals are demodulated and subject to diversity synthesis thereby realizing 4-branch diversity reception. Moreover, top antennas 25-28 are provided just after the directivity antennas 21-24 and before the synthesis distribution phase shifter 30.