Abstract: The present invention is designed to provide a communication system, a local area base station apparatus, a mobile terminal apparatus and a communication method that can provide highly efficient local area radio access. In a communication system in which a mobile terminal apparatus performs radio communication with a wide area base station apparatus that covers a wide area, using a first carrier frequency, and performs radio communication with a local area base station apparatus that covers a local area, using a second carrier frequency, the wide area base station apparatus allocates different frequencies between the uplink and the downlink in the first carrier frequency and communicates with the mobile terminal apparatus, and the local area base station apparatus dynamically switches between the uplink and the downlink in the second carrier frequency on a per time basis based on the communication environment, and communicates with the mobile terminal apparatus.