Cell reselection control method, base station, and radio terminal

A cell reselection control method in a mobile communication system, the control method comprising:

• transmitting through broadcast signaling, by a base station, as a redistribution parameter used for a redistribution function, a first redistribution parameter applied to a radio terminal in a first coverage and a second redistribution parameter applied to a radio terminal in a second coverage outside the first coverage, wherein the second coverage is a coverage extended by an enhanced coverage function including repetitive transmissions;
• acquiring, by the radio terminal in an idle mode in the second coverage, the transmitted second redistribution parameter;
• and
• performing, by the radio terminal in the idle mode in the second coverage, cell reselection using the acquired second redistribution parameter, wherein
• the redistribution function is a function in which a plurality of radio terminals in the idle mode concentrated on a specific cell or a specific frequency are distributed in cells and/or frequencies based on an identifier of each of the plurality of radio terminals,
• the redistribution parameter includes a parameter indicating a probability for each cell or a parameter indicating a probability for each frequency.