Radio base station, user terminal, radio communication system and radio communication method

A radio communication method in which a radio base station transmits downlink control information for a user terminal using an enhanced downlink control channel frequency-division-multiplexed with a downlink shared data channel, the radio communication method comprising the steps of:

• by the radio base station,
• configuring the user terminal with a resource set including a plurality of resource blocks allocated to the enhanced downlink control channel;
• and
• transmitting, to the user terminal, a pattern index indicating a resource block pattern that is a sequence of the resource blocks that are included in the resource set and information indicating a number (n) of resource blocks that are included in the resource set,
• wherein the pattern index is calculated based on a total number (N) of resource blocks that are included in a downlink bandwidth, the number (n) of resource blocks and indexes (Ai (1≦i≦n)) assigned to the resource blocks in the resource block pattern.