Mobile radio communication system with macro and micro cell handoff based on mobile determined crossing rates and fading rates

Claim 1

A mobile radio communication system, comprising: a plurality of macro cell radio base stations that respectively form macro cells; a plurality of micro cell radio base stations that respectively form micro cells, each of the micro cells being smaller than each of the macro cells, at least part of each of the macro cells overlapping with a relevant macro cell; a radio-base-station controlling station that controls said macro cell radio base stations and said micro cell radio base stations; and a mobile station, being present in at least either a macro cell or a micro cell, the mobile station communicating with one of said macro cell radio base stations or one of said micro cell radio base stations, wherein each of said macro cell radio base stations and said micro cell radio base stations comprises: a broadcasting unit that broadcasts system information through a relevant control channel corresponding to control information received from said radio-base-station controlling station, and wherein said mobile station comprises: a speed determining unit that measures the state of the received control channel and determines the moving speed of said mobile station; and a channel selecting unit that receives the system information and selects an optimum channel for communicating with the relevant radio base station from channels that the system information represents corresponding to the moving speed determined by said speed determining unit, wherein the moving speed of said mobile station is detected with one of: a) a fading rate based on a fluctuation level and a fluctuation period of a received signal per unit time, and b) a crossing rate of a received signal received on the received control channel, the crossing rate being calculated with respect to a predetermined threshold value, wherein, when the crossing rate is greater than a predetermined crossing rate within a constant time period, the mobile station is determined to be moving above a predetermined speed level, wherein, at call initiation, said mobile base station communicates with one of said macro cell radio base stations when the moving speed of said mobile station exceeds a predetermined speed, wherein, at call initiation, said mobile base station communicates with one of said micro cell radio base stations when the moving speed of said mobile station is less than said predetermined speed, and wherein, when the mobile station is currently communicating with one of said macro cell base stations, said mobile station switches to perform communicating with one of said micro cell base stations only when both a) the moving speed of said mobile station is less than said predetermined speed, and b) a field intensity of the received control channel of said one of said macro cell base stations is less than a predetermined field intensity.