Mobile communication method, base station, and user terminal

1. A mobile communication method comprising:

performing, by a base station, communication by using a narrow band which is a second bandwidth narrower than a first bandwidth compatible with a first user equipment in one unit time, wherein the second bandwidth is a bandwidth of six resource blocks;

transmitting, from the base station via an M-PDCCH (MTC Physical Downlink Control Channel), a DCI (Downlink Control Information) including allocation information for allocating a second user equipment an extended band having a third bandwidth wider than the second bandwidth and narrower than the first bandwidth in the one unit time, wherein the third bandwidth is equal to the integral multiple of six resource blocks, the DCI having a predetermined DCI format; and

transmitting from the base station to the second user equipment, an RRC (Radio Resource Control) message including an information element designating an interpreting method for the allocation information included in the DCI having the predetermined DCI format, wherein

the extended band includes a fixed number of narrow bands,

a frequency domain includes a plurality of extended bands each identified by an index, and

the allocation information includes an index identifying one extended band of the plurality of extended bands.

2. The mobile communication method according to claim 1 , wherein

the allocation information comprises information indicating a narrow band included in the extended band.

3. The mobile communication method according to claim 1 , further comprising

performing, by the second user equipment, communication with the base station by using the allocated extended band based on the allocation information received from the base station.

4. The mobile communication method according to claim 1 , wherein

the extended band is constituted by a plurality of narrow bands.

5. The mobile communication method according to claim 1 , wherein

the allocation information indicates a length of the extended band in a frequency direction.

6. The mobile communication method according to claim 1 , wherein the information includes information indicating an arrangement of physical resource blocks allocated to the second user equipment in the extended band.

7. The mobile communication method according to claim 1 , further comprising:

transmitting, from the base station, information indicating a predetermined number of times of repetitions in the communication; and

if a predetermined condition is satisfied, stopping repeated transmission in the communication with the number of times of repetitions different from the predetermined number of times of repetitions.

8. The mobile communication method according to claim 7 , further comprising:

notifying, from the base station, information specifying the number of times of offsets with respect to the predetermined number of times of repetitions,

wherein the predetermined condition is that the number of times of offsets is other than zero, and

the stopping includes stopping repeated transmission in the communication with the number of times of repetitions based on the number of times of offsets and the predetermined number of times of repetitions.

9. A base station comprising:

a controller configured to perform communication by using a narrow band which is a second bandwidth narrower than a first bandwidth compatible with a first user equipment in one unit time, wherein the second bandwidth is a bandwidth of six resource blocks; and

a transmitter configured to transmit, to a second user equipment via an M-PDCCH (MTC Physical Downlink Control Channel), a DCI (Downlink Control Information) including allocation information for allocating an extended band having a third bandwidth wider than the second bandwidth and narrower than the first bandwidth in the one unit time, wherein the third bandwidth is equal to the integral multiple of six resource blocks, the DCI having a predetermined DCI format, wherein

the transmitter is configured to transmit to the second user equipment, an RRC (Radio Resource Control) message including an information element designating an interpreting method for the allocation information included in the DCI having the predetermined DCI format transmitted from the base station via the M-PDCCH,

the extended band includes a fixed number of narrow bands,

a frequency domain includes a plurality of extended bands each identified by an index, and

the allocation information includes an index identifying one extended band of the plurality of extended bands.

10. A user equipment for a system including a base station configured to perform communication by using a narrow band which is a second bandwidth narrower than a first bandwidth compatible with a first user terminal in one unit time, the user equipment comprising:

at least one processor configured to

receive, from a base station, a DCI (Downlink Control Information) including allocation information for allocating an extended band having a third bandwidth wider than the second bandwidth and narrower than the first bandwidth in the one unit time, wherein the third bandwidth is equal to the integral multiple of six resource blocks, the DCI having a predetermined DCI format,

receive, from the base station, an RRC (Radio Resource Control) message including an information element designating an interpreting method for the allocation information included in the DCI having the predetermined DCI format, and

perform communication with the base station by using the allocated extended band based on the allocation information received from the base station, wherein

the extended band includes a fixed number of narrow bands,

a frequency domain includes a plurality of extended bands each identified by an index, and

the allocation information includes an index identifying one extended band of the plurality of extended bands.