Method and apparatus for determining harq timing in communication systems

A method performed by a user equipment (UE) in a communication system supporting Carrier Aggregation (CA) of a primary cell and at least one secondary cell(s), the method comprising:

• receiving a downlink physical channel from a base station through one of the at least one secondary cell(s);
• and
• transmitting, to the base station, a Hybrid Automatic Repeat Request (HARQ) feedback corresponding to the downlink physical channel,
• wherein
• if the UE is configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD),
• a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of a subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the subframe in the primary cell, and
• if the UE is not configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD):
• if a first subframe is either a downlink subframe or a special subframe in the primary cell, a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the first subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the first subframe in the primary cell;
• and
• if a second subframe is an uplink subframe in the primary cell, a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the second subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of either a downlink subframe or a special subframe of the primary cell which is closest to the second subframe.

A method performed by a base station in a communication system supporting Carrier Aggregation (CA) of a primary cell and at least one secondary cell(s), the method comprising:

• transmitting a downlink physical channel to a user equipment (UE) through one of the at least one secondary cell(s);
• and
• receiving, from the UE, a Hybrid Automatic Repeat Request (HARQ) feedback corresponding to the downlink physical channel,
• wherein
• if the UE is configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD),
• a timing of receiving a HARQ feedback corresponding to a downlink physical channel of a subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of receiving a HARQ feedback corresponding to a downlink physical channel of the subframe in the primary cell, and
• if the UE is not configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD):
• if a first subframe is either a downlink subframe or a special subframe in the primary cell, a timing of receiving a HARQ feedback corresponding to a downlink physical channel of the first subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of receiving a HARQ feedback corresponding to a downlink physical channel of the first subframe in the primary cell;
• and
• if a second subframe is an uplink subframe in the primary cell, a timing of receiving a HARQ feedback corresponding to a downlink physical channel of the second subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of receiving a HARQ feedback corresponding to a downlink physical channel of either a downlink subframe or a special subframe of the primary cell which is closest to the second subframe.

A user equipment (UE) in a communication system supporting Carrier Aggregation (CA) of a primary cell and at least one secondary cell(s), the UE comprising a transceiver configured to:

• receive a downlink physical channel from a base station through one of the at least one secondary cell(s);
• and
• transmit, to the base station, a Hybrid Automatic Repeat Request (HARQ) feedback corresponding to the downlink physical channel,
• wherein
• if the UE is configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD),
• a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of a subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the subframe in the primary cell, and
• if the UE is not configured to monitor a control channel in another cell for scheduling the one of the at least one secondary cell(s), and when the primary cell is configured as Time Divisional Duplex (TDD) and the one of the at least one secondary cell(s) is configured as Frequency Divisional Duplex (FDD):
• if a first subframe is either a downlink subframe or a special subframe in the primary cell, a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the first subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the first subframe in the primary cell;
• and
• if a second subframe is an uplink subframe in the primary cell, a timing of transmitting a HARQ feedback corresponding to a downlink physical channel of the second subframe in the one of the at least one secondary cell(s) is identical with a TDD timing of transmitting a HARQ feedback corresponding to a downlink physical channel of either a downlink subframe or a special subframe of the primary cell which is closest to the second subframe.