What is UL – Uplink?
Uplink (UL) is the transmission direction from the User Equipment (UE) to the base station (gNB in 5G). It carries all user-generated data, voice, video conferencing uploads, IoT sensor reports, and control feedback information from the device to the network. Uplink capacity is typically lower than downlink in most deployments.
How Does UL – Uplink Work?
In 5G NR, the uplink supports two waveforms: CP-OFDM (same as downlink, flexible and efficient) and DFT-s-OFDM (lower PAPR, better for power-limited UEs at cell edges). The UE transmits on the Physical Uplink Shared Channel (PUSCH) for data and the Physical Uplink Control Channel (PUCCH) for CSI reports, HARQ feedback, and scheduling requests. The gNB schedules all uplink transmissions via Uplink Control Information (UCI/DCI).
Use Cases
Voice calls, video uploads, IoT sensor data reporting, CSI/HARQ feedback to enable downlink optimisation, machine control uplink commands.
3GPP / Standards Reference
3GPP TS 38.211 (Physical Channels), TS 38.213 (UL Scheduling)
Related Terms
DL | gNB | UE | DFT-s-OFDM | FDD | TDD
Learn More
This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
