PRACH Preamble Power Control in Carrier Aggregation
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Solution Overview
Problem
In next-generation wireless communication systems, determining the optimal transmission power for a preamble in a random access procedure across multiple cells is challenging due to varying path losses and mobility-induced channel characteristics, which affects the reliability of broadband communications.
Innovation Solution
A method for determining the transmission power of a physical random access channel (PRACH) preamble in a secondary cell (SCell) based on the downlink path loss, using equations that consider the path loss difference between the primary cell (PCell) and SCell, allowing for efficient power adjustment and reliable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission power is increased to overcome path loss in SCell, then communication reliability is improved, but energy consumption increases
Solution Approach 1:
The patent dynamically adjusts transmission power parameters based on measured path loss conditions. The UE calculates path loss for each SCell and determines appropriate preamble transmission power levels, changing the power parameter adaptively rather than using fixed high power, thus achieving reliable communication while optimizing energy consumption.
2Reliability
If path loss estimation is performed for each SCell to determine optimal power, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the path loss estimation process by cell, where the UE independently calculates path loss for each SCell based on downlink reference signals. This segmentation allows targeted power control per cell without requiring complex centralized control, improving reliability while managing device complexity through distributed calculation.
Solution Approach 2:
The UE performs self-service by autonomously measuring downlink path loss and determining its own preamble transmission power for each SCell without needing explicit power assignment from the base station. This self-determination mechanism improves communication reliability while avoiding the complexity of centralized power management.
3Adaptability or versatility
If random access procedure is performed for multiple cells, then adaptability is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary path loss estimation for each SCell before the random access procedure. By pre-calculating path loss values based on downlink measurements, the UE can quickly determine appropriate transmission power without time-consuming power adjustment during the access procedure, thus reducing access time while maintaining adaptability across multiple cells.
Data Source
AI summary
Provided are a method and an apparatus for determining transmission power of a preamble in a wireless communication system. A terminal estimates secondary cell (SCell) path loss with respect to a downlink (DL) component carrier (CC), which is in a linkage relationship with an uplink (UL) component carrier inside the SCell; decides the transmission power of a physical random access channel (PRACH) preamble based on the SCell path loss that is estimated; and transmits the PRACH preamble to a base station through the UL CC inside the SCell, based on the transmission power that is decided, wherein the SCell and a primary cell (PCell) comprises a carrier aggregation (CA) system, the PCell is a cell from which the terminal performs radio resource control (RRC) connection with the base station, and wherein the Scell is at least one cell from residual cells in the carrier aggregation excluding the PCell.