TechLTEworld

TPC (Transmit Power Control) In-Depth Understanding

The video explains the Transmit Power Control (TPC) command, a 5G uplink mechanism that lets the gNodeB tell a UE how much transmission power to use, primarily to extend battery life. TPC operates within the broader uplink power‑control framework, which includes open‑loop control—where the UE computes power from parameters such as P0, number of RBs and MCS—and closed‑loop control, which adds the gNodeB‑issued TPC adjustment. In 5G the command is carried in a two‑bit DCI payload using the 2_2 or 2_3 DCI formats. Two operation modes are described: accumulated TPC, which applies adjustments relative to the previously set power, and absolute TPC, which applies each command directly to the UE’s calculated power. The presenter illustrates the difference with numeric examples (e.g., a –1 dB step from 20 dBm to 19 dBm) and notes that absolute TPC, introduced in 5G, eliminates the need to track power history, reducing latency and overhead. For network operators, the ability to fine‑tune UE transmit power translates into lower battery drain for devices, more stable uplink interference levels, and improved spectral efficiency—key factors as 5G traffic scales.