LTE-FDD implies that downlink and uplink transmission take place in different, sufficiently separated, frequency bands, while TDD implies that downlink and uplink transmission take place in different, non overlapping time slots. Thus, TDD can operate in unpaired spectrum, whereas FDD requires paired spectrum .
Read moreCan I combine FDD and TDD?
3GPP has finalized the work on TDD-FDD CA, which offers the possibility to aggregate FDD and TDD carriers jointly . The main target with introducing the support for TDD-FDD CA is to allow the network to boost the user throughput by aggregating both TDD and FDD toward the same UE.
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