Systems and methods for carrier aggregation

An evolved Node B (eNB) for performing carrier aggregation, comprising:

• a processor;
• memory in electronic communication with the processor, wherein instructions stored in the memory are executable to:
• determine a duplex method of each serving cell for carrier aggregation, wherein a primary cell is a frequency-division duplexing (FDD) cell and a secondary cell is a time-division duplexing (TDD) cell;
• and
• for receiving hybrid automatic repeat request acknowledgement/negative acknowledgement (HARQ-ACK) information using a physical uplink control channel (PUCCH) format 1b with channel selection in a first subframe:
• determine whether to use a PUCCH format 1b procedure for a single FDD serving cell or a PUCCH format 1b with channel selection procedure for multiple FDD serving cells based on whether a second subframe, which is a subframe four subframes before the first subframe, is an uplink subframe for the secondary cell;
• and
• use the PUCCH format 1b procedure for the single FDD serving cell, in a case that the second subframe is the uplink subframe for the secondary cell.

A method for performing carrier aggregation by a user equipment (UE), comprising:

• determining a duplex method of each serving cell for carrier aggregation, wherein a primary cell is a frequency-division duplexing (FDD) cell and a secondary cell is a time-division duplexing (TDD) cell;
• and
• for transmitting hybrid automatic repeat request acknowledgement/negative acknowledgement (HARQ-ACK) information using a physical uplink control channel (PUCCH) format 1b with channel selection in a first subframe:
• determining whether to use a PUCCH format 1b procedure for a single FDD serving cell or a PUCCH format 1b with channel selection procedure for multiple FDD serving cells based on whether a second subframe, which is a subframe four subframes before the first subframe, is an uplink subframe for the secondary cell;
• and
• using the PUCCH format 1b procedure for the single FDD serving cell, in a case that the second subframe is the uplink subframe for the secondary cell.

A method for performing carrier aggregation by an evolved Node B (eNB), comprising:

• determining a duplex method of each serving cell for carrier aggregation, wherein a primary cell is a frequency-division duplexing (FDD) cell and a secondary cell is a time-division duplexing (TDD) cell;
• and
• for receiving hybrid automatic repeat request acknowledgement/negative acknowledgement (HARQ-ACK) information using a physical uplink control channel (PUCCH) format 1b with channel selection in a first subframe:
• determining whether to use a PUCCH format 1b procedure for a single FDD serving cell or a PUCCH format 1b with channel selection procedure for multiple FDD serving cells based on whether a second subframe, which is a subframe four subframes before the first subframe, is an uplink subframe for the secondary cell;
• and
• using the PUCCH format 1b procedure for the single FDD serving cell, in a case that the second subframe is the uplink subframe for the secondary cell.