CLAIMS
1. A mobile communication system comprising user equipments, a first base
station and a second base station, the user equipments performing data
transmission/reception using an orthogonal frequency division multiplexing (OFDM)
system as a downlink access system and a single career frequency division multiple
access (SC-FDMA) system as an uplink access system, the first base station provided to a
first cell made open only to specific ones of said user equipments or subscribers and
transmitting, to said user equipments, control signals including a downlink
synchronization signal using a radio frame including a predetermined number of
subframes, the second base station provided to a second cell made available for
non-specific ones of said user equipments or users and transmitting, to said user
equipments, control signals including a downlink synchronization signal using a radio
frame including the same number of subframes as those of said radio frame used in
transmission by said first base station, wherein:
said first base station assigns said control signals to a first subframe and a second subframe among a plurality of subframes constituting said radio frame;
said second base station assigns said control signals to a third subframe and a fourth subframe among the plurality of subframes constituting said radio frame, the third subframe and the fourth subframe being shifted from said first subframe and said second subframe by a predetermined number of subframes, respectively; and
said first base station and said second base station transmit said control signals in synchronization.
2. The mobile communication system according to Claim 1, wherein:
the downlink control signal assigned to each of the plurality of subframes

constituting said radio frame and transmitted is assigned to any symbol among a plurality of symbols constituting said subframe; and
said second base station assigns the downlink control signal to a symbol shifted by a predetermined number of symbols from said symbol to which said first base station assigns said downlink control signal.
3. A mobile communication system comprising user equipments, base stations and a radio network controller, the user equipments performing data transmission/reception using an orthogonal frequency division multiplexing (OFDM) system as a downlink access system and a single career frequency division multiple access (SC-FDMA) system as an uplink access system, the base stations provided to cells for specific subscribers that are communication cells allowed to be used by specific ones of said user equipments or subscribers and cells for non-specific users that are communication cells allowed to be used by non-specific ones of said user equipments or users, the radio network controller managing a desired tracking area in which said user equipments are located through a plurality of said base stations and performing paging on said user equipments, in which said user equipments receive, from said base stations, cell identification information (PCI) being the information assigned to each of said communication cells and provided for identifying said communication cells to select the cell for communication,
wherein said user equipments each receive said cell identification information included in a downlink synchronization signal transmitted from said base station, judge whether said received cell identification information coincides with notified cell identification information that is notified from a serving cell performing scheduling for allocating radio resources to said user equipments and indicates a base station having the

same identification information as that of said serving cell, and in a case where said received cell identification information and said notified cell identification information do not coincide with each other, eliminate the base station corresponding to said received cell identification information from candidates for cell selection.