https://gandh.com/products/fiber-optics/sm-couplers/duplexing-wdm-1310-1550-1625nm
G&H Products │ SM Couplers │ Duplexing WDM 1310-1550, 1625nm
A two-channel WDM that simultaneously splits or couples a pair of wavelengths for combinations of O/L, O/C, or O/U bands.
g hproductscouplersduplexingwdm
https://3gpp-explorer.com/glossary/fdd/
FDD — Frequency Division Duplexing | 3GPP Glossary
FDD is a duplexing method where uplink and downlink transmissions occur simultaneously on separate, paired frequency bands, enabling full-duplex…
frequency division duplexingfddglossary