Methods, systems and devices for multi-carrier communications involving one or more TDD component carriers and one or more FDD component carriers in a wireless communication network are described. Some described embodiments relate to systems and methods for multi-carrier communications for a half-duplex device. The described methods, systems and devices may simplify scheduling timing by multi-carrier communications, e.g., determination of hybrid automatic repeat request (HARQ) and / or FDD + TDD carrier aggregation.
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