Control Channel Design for Carrier Aggregation between LTE FDD and LTE TDD Systems

Carrier aggregation (CA) has been proposed within 3GPP to aggregate multiple component carriers (CCs) in LTE-Advanced system to achieve higher peak data rate. In this paper, we propose CA between FDD and TDD carriers in order to utilize FDD and TDD spectrums more efficiently. By comparing the differences in control channel between LTE FDD and TDD specifications, three problems in the case of CA between FDD and TDD carriers are identified, and we then propose the respective solutions and analyze their pros and cons. It is shown that CA between FDD and TDD carriers can provide system flexibility and performance benefits for the operators which own both FDD and TDD spectrums.