# US 2017/0288754 A1 · Base station apparatus, terminal device, and communication method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288754 A1 - Document ID: US20170288754A1 - Status: Published application - Kind: A1 - Application number: 15/507,281 - Filed: 2015-08-28 - Published: 2017-10-05 - Earliest claimed: 2014-09-24 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: Hiromichi TOMEBA; Jungo GOTO; Osamu NAKAMURA; Shiro WAKAHARA; Yasuhiro HAMAGUCHI - Web page: https://patentgrep.com/patent/US20170288754A1 ## CPC - H04B 7/0617: {for beam forming} - H04B 7/024: Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems - H04B 7/0413: MIMO systems - H04B 7/0452: Multi-user MIMO systems - H04W 56/0015: {one node acting as a reference for the others} - H04W 72/046: {the resource being in the space domain, e.g. beams} - H04W 16/28: using beam steering - H04W 16/32: Hierarchical cell structures - H04W 92/20: between access points - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Provided are a base station apparatus, a terminal device, and a communication method that can realize a small cell network while reducing load on the terminal device, the small cell network including a small cell performing massive MIMO transfer. The base station apparatus of the present invention is a second base station apparatus included in a communication system in which a plurality of the second base station apparatuses capable of acquiring assistance information from a first base station apparatus communicates with a terminal device, the base station apparatus including a codebook that describes a plurality of linear filters, in which the same cell identification number as at least one of the other second base station apparatuses is configured, and a synchronization signal correlated with the cell identification number is transmitted on the basis of the plurality of linear filters after first precoding of the synchronization signal. ## Claims ### Claim 1 A second base station apparatus that includes a secondary cell and communicates with a first base station apparatus including a primary cell and with a terminal device, the apparatus comprising: a control unit that acquires, from the first base station apparatus, assistance information which includes information indicating a cell identification number and information indicating a timing of transmission of a synchronization signal correlated with the cell identification number; and a transmission unit that performs beamforming on the synchronization signal and transmits the synchronization signal at the timing of transmission in the secondary cell. ### Claim 2 (depends on 1) The second base station apparatus according to claim 1, wherein the assistance information includes information indicating a cycle of transmission of the synchronization signal. ### Claim 3 (depends on 2) The second base station apparatus according to claim 2, wherein the assistance information includes information specifying the beamforming. ### Claim at position 4 4-6. (canceled) ### Claim 7 A first base station apparatus that includes a primary cell and communicates with a second base station apparatus including a secondary cell and with a terminal device, the apparatus comprising: a control unit that configures a cell identification number of the second base station apparatus and a timing of transmission of a synchronization signal correlated with the cell identification number; and a transmission unit that notifies the second base station apparatus of first assistance information which includes information indicating the cell identification number and information indicating the timing of transmission, and transmits, to the terminal device in the primary cell, second assistance information which includes information indicating the timing of transmission. ### Claim at position 6 8-9. (canceled) ### Claim 10 (depends on 3) The second base station apparatus according to claim 3, wherein the transmission unit multiplexes and transmits the synchronization signal with a signal that is different from the synchronization signal. ### Claim 11 (depends on 10) The second base station apparatus according to claim 10, wherein the transmission unit is capable of configuring a plurality of different types of beamforming in the synchronization signal. ### Claim 12 (depends on 11) The second base station apparatus according to claim 11, wherein the cell identification number is the same as at least one of other second base station apparatuses. ### Claim 13 (depends on 7) The first base station apparatus according to claim 7, wherein the first assistance information includes information specifying beamforming applied to the synchronization signal. ### Claim 14 (depends on 7) The first base station apparatus according to claim 7, wherein the second assistance information includes information indicating a signal sequence configured in the synchronization signal. ### Claim 15 (depends on 14) The first base station apparatus according to claim 14, wherein a plurality of the second base station apparatuses is separated into a plurality of groups, the cell identification number of the second base station apparatus is determined on the basis of the separation, and information related to the cell identification number is signaled to the second base station apparatus. ### Claim 16 (depends on 15) The first base station apparatus according to claim 15, wherein the cell identification number is determined on the basis of a frequency band that the second base station apparatus uses in communication. ### Claim 17 A terminal device that is connected to a primary cell and a secondary cell, the device comprising: a control unit that acquires assistance information including information indicating a timing of transmission of a synchronization signal in the primary cell; and a reception unit that performs synchronization processing of the synchronization signal transmitted in the secondary cell on the basis of the information indicating the timing of transmission of the synchronization signal. ### Claim 18 (depends on 17) The terminal device according to claim 17, wherein a cell identification number is correlated with the synchronization signal, and the reception unit configures, in the primary cell, a candidate of the cell identification number for the synchronization processing.