downlink subframes or special subframes that are included in a bundling window associated with an uplink subframe further the ue may select the lesser of the determined value or the determined number of downlink subframes or special subframes included in the bundling window to correspond to a number of subframes for which the ue needs to feedback harq ack bits for the first serving cell application_number US 201414314296 A description illustrative embodiments of the present disclosure include but are not limited to methods systems computer readable media and apparatuses for determining a size of a harq ack codebook in wireless communication networks various embodiments may provide user equipment ue that operate in conformance with release 11 of 3gpp lte hereinafter u201c rel 11 u201d and later releases with the ability to determine harq ack codebook size on pusch in a manner to reduce harq ack overhead while maintaining harq ack performance for interband ca of tdd ccs with different ul dl configurations for different serving cells in this manner described ues may adaptively determine the desired harq ack codebook size to puncture the pusch res that will reduce negative impact on the pusch with little to no additional overhead various embodiments may be described with reference to specific configurations e g tdd ul dl configurations and special subframe configurations formats e g dci formats modes e g transmission modes etc these configurations formats modes etc may be defined consistent with presently published lte documents e g rel 10 and or rel 11 technical specifications various aspects of the illustrative embodiments will be described using.