# US 9,439,181 B2 · Radio communication system, radio base station apparatus, user terminal, and radio communication method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,439,181 B2 - Document ID: US9439181B2 - Status: Granted - Kind: B2 - Application number: 14/355,645 - Filed: 2012-11-08 - Published: 2014-08-28 - Granted: 2016-09-06 - Earliest claimed: 2011-11-09 - Assignees: Ntt Docomo, Inc. - Applicants: Ntt Docomo, Inc. - Inventors: Kazuaki Takeda; Liu Liu; Lan Chen; Qin Mu; Wenbo Wang - Web page: https://patentgrep.com/patent/US9439181B2 ## CPC - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04J 3/00: Time-division multiplex systems (H04J14/00 takes precedence; relay systems H04B7/14; selecting techniques H04Q) - H04L 5/001: {the frequencies being arranged in component carriers} - H04L 5/0053: {Allocation of signalling, i.e. of overhead other than pilot signals} - H04L 5/1469: {using time-sharing} - H04L 5/0094: {Indication of how sub-channels of the path are allocated} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract According to the present invention, even when the ratio between uplink subframes and downlink subframes is changed in each component carrier in TDD carrier aggregation, it is still possible to prevent a decrease in capacity. With the radio communication method according to the present invention, a radio base station apparatus generates a downlink control channel signal containing downlink control information including carrier indicator field information, and transmits the downlink control channel signal to a user terminal, and the user terminal receives the downlink control channel signal, and executes signal processing with respect to the downlink signal in accordance with the downlink control information. In this case, the carrier indicator field information is information which associates a carrier index and the index of a secondary cell subframe to be scheduled. ## Claims ### Claim 1 A radio communication system comprising: a radio base station apparatus configured to: generate downlink control information including carrier indicator field (CIF) representing a carrier index and a subframe index; and transmit the downlink control information including the CIF; and a user terminal configured to: receive the downlink control information including the CIF; and perform signal processing on a downlink shared channel which is transmitted by time division duplexing in a component carrier and a subframe indicated by the carrier index and the subframe index which are represented by the CIF included in the downlink control information. ### Claim 2 (depends on 1) The radio communication system according to claim 1, wherein, the radio base station apparatus is configured to transmit the downlink control information including the CIF in a special subframe of a primary cell, when a configuration in which there are fewer downlink subframes in the primary cell than downlink subframes in the secondary cell is used. ### Claim 3 (depends on 2) The radio communication system according to claim 2, wherein the radio base station apparatus is configured to transmit mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling. ### Claim 4 (depends on 1) The radio communication system according to claim 1, wherein the radio base station apparatus transmits mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling. ### Claim 5 A radio base station apparatus comprising: a receiving section that receives an unlink signal; a software module generating downlink control information including carrier indicator field (CIF) representing a carrier index and a subframe index, wherein the carrier index and the subframe index respectively indicates a component carrier and a subframe in which a downlink shared channel is transmitted by time division duplexing; and a transmission section that transmits the downlink control information including the CIF to the user terminal. ### Claim 6 (depends on 5) The radio base station apparatus according to claim 5, wherein, the transmission section transmits the downlink control information including the CIF in a special subframe of a primary cell, when a configuration in which there are fewer downlink subframes in the primary cell than downlink subframes in the secondary cell is used. ### Claim 7 (depends on 6) The radio base station apparatus according to claim 6, wherein the transmission section transmits mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling. ### Claim 8 (depends on 5) The radio base station apparatus according to claim 5, wherein the transmission section transmits mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling. ### Claim 9 A user terminal comprising: a receiving section that receives downlink control information including carrier indicator field (CIF) representing a carrier index and a subframe index; a software module performing signal processing on a downlink shared channel which is transmitted by time division duplexing in a component carrier and a subframe respectively indicated by the carrier index and the subframe index which are represented by the CIF in the downlink control information; and a transmission section that transmits an uplink signal. ### Claim 10 A radio communication method comprising the steps of: generating, by a radio base station apparatus, downlink control information including carrier indicator field (CIF) representing a carrier index and a subframe index; transmitting, by the radio base station apparatus, the downlink control information including the CIF; and receiving, by a user terminal, the downlink control information including the CIF; and performing, by the user terminal, signal processing on a downlink shared channel which is transmitted by time division duplexing in a component carrier and a subframe respectively indicated by the carrier index and the subframe index which are represented by the CIF in the downlink control information. ### Claim 11 (depends on 10) The radio communication method according to claim 10, wherein the radio base station apparatus transmits the downlink control information including the CIF in a special subframe of a primary cell, when a configuration in which there are fewer downlink subframes in the primary cell than downlink subframes in the secondary cell is used. ### Claim 12 (depends on 11) The radio communication method according to claim 11, wherein the radio base station apparatus transmits mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling. ### Claim 13 (depends on 10) The radio communication method according to one of claim 10, wherein the radio base station apparatus transmits mapping information of a subframe of the primary cell and a subframe of the secondary cell to the user terminal through higher layer signaling.