5G UL and DL Decoupling

UL and DL Decoupling defines new paired spectrum, with C-band for downlink transmission and a sub-3 GHz band (for example, 1.8 GHz) for uplink transmission, thereby improving C-band uplink coverage.

The C-band TDD system boasts a large bandwidth and is regarded as the gold frequency band for 5G Enhanced Mobile Broadband (eMBB) services.

A vast majority of global operators have selected C-band spectrum as the preferential 5G frequency band. Downlink coverage is better than uplink coverage on C-band TDD system due to large downlink transmit power of the gNodeB and disproportion in uplink and downlink timeslot allocations of NR.

The limited uplink coverage has become a key technology bottleneck for deploying 5G network. The application of technologies such as beamforming and cell-specific reference signal (CRS)-free reduces downlink interference and further increases the difference between C-band TDD system uplink and downlink coverage.