5G • 5G-Advanced (Rel-18)
Enhanced UL Precoding Codebook
Rel-18 Uplink Codebook Subsets for Unequal Antenna Power
Standardizes non-uniform codebook subsets that allow handheld devices to transmit full uplink power even when individual power amplifiers operate at different levels.
Technical Explanation
Handheld UEs often cannot drive equal output power across all 4 transmit antennas due to regulatory SAR (Specific Absorption Rate) limits near the user's head or thermal throttling. Rel-18 standardizes enhanced uplink codebooks with non-uniform power scaling coefficients, enabling the UE to radiate maximum legally allowable power without violating RF exposure regulations.
Key Functions
- Accommodates unequal power amplifier outputs across commercial smartphone antennas
- Maximizes total radiated uplink power while strictly complying with regulatory SAR limits
- Eliminates power wastage caused by legacy codebooks that enforced equal power across all ports
- Extends uplink battery efficiency and enhances cell-edge uplink throughput
Specifications
3GPP TS 38.211, TS 38.214 (Rel-18)
Interfaces
Uu (PUSCH)
Related 5G Concepts
Want to memorize 5G concepts like this one?
Study it with SuperMemo SM-2 spaced repetition flashcards.