A communication system for inter-base station carrier aggregation, comprising: a first serving base station of a user equipment, UE, which is named as a primary base station; and another serving base station of the UE which is named as a secondary base station; wherein the primary base station is configured to send a message including indication information to the UE, wherein the indication information requests the UE to report a timing offset between a primary cell, PCell, of the primary base station and a cell of the secondary base station; and receive the timing offset from the UE; and the secondary base station is configured to receive the timing offset from the primary base station; and calculate a corrected measurement gap information according to a measurement gap information and the timing offset, wherein the measurement gap information is used by the primary base station to instruct the UE to perform measurement in a first measurement gap period indicated by the measurement gap information; and stop scheduling the UE in a second measurement gap period indicated by the corrected measurement gap information such that neither information nor data is transferred between the UE and the secondary base station. a first serving base station of a user equipment, UE, which is named as a primary base station; and another serving base station of the UE which is named as a secondary base station; wherein the primary base station is configured to send a message including indication information to the UE, wherein the indication information requests the UE to report a timing offset between a primary cell, PCell, of the primary base station and a cell of the secondary base station; and receive the timing offset from the UE; and send a message including indication information to the UE, wherein the indication information requests the UE to report a timing offset between a primary cell, PCell, of the primary base station and a cell of the secondary base station; and receive the timing offset from the UE; and the secondary base station is configured to receive the timing offset from the primary base station; and calculate a corrected measurement gap information according to a measurement gap information and the timing offset, wherein the measurement gap information is used by the primary base station to instruct the UE to perform measurement in a first measurement gap period indicated by the measurement gap information; and stop scheduling the UE in a second measurement gap period indicated by the corrected measurement gap information such that neither information nor data is transferred between the UE and the secondary base station. receive the timing offset from the primary base station; and calculate a corrected measurement gap information according to a measurement gap information and the timing offset, wherein the measurement gap information is used by the primary base station to instruct the UE to perform measurement in a first measurement gap period indicated by the measurement gap information; and stop scheduling the UE in a second measurement gap period indicated by the corrected measurement gap information such that neither information nor data is transferred between the UE and the secondary base station. <EOS>