SRS Power Headroom Reporting with Insertion Loss Compensation
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Solution Overview
Problem
In wireless communications systems, especially in downlink multiple input multiple output (MIMO) with time division duplex (TDD) bands, large and unknown insertion losses in receive-only antennas lead to incorrect channel estimation, impacting downlink scheduling and throughput due to unaccounted power relaxations in UE antennas sharing power amplifiers.
Innovation Solution
The UE transmits an indication of differences in insertion losses between a reference SRS port and additional SRS ports, along with a power headroom report for one SRS port with the smallest insertion loss, allowing the network to correct downlink channel estimates and compensate for power imbalances across SRS ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If power headroom reports are transmitted for all SRS ports, then accurate downlink channel estimation is achieved, but UE signaling overhead increases
Solution Approach 1:
The patent extracts only the essential power headroom information from all SRS ports by identifying and reporting only the port with the smallest insertion loss (reference port) rather than reporting power headroom for all ports. The network then infers power headroom values for other ports using the reported reference port data and insertion loss difference information, thereby reducing signaling overhead while maintaining estimation accuracy.
Solution Approach 2:
The patent introduces insertion loss difference information as an intermediary parameter that enables the network to calculate power headroom for multiple ports based on a single reference port report. This intermediary allows the network to compensate for the reduced signaling by using the insertion loss differences between ports to infer the power headroom values for all ports.
2Quantity of substance
If power headroom reports are transmitted for all SRS ports, then complete power information is provided, but device complexity increases
Solution Approach 1:
The patent extracts only the necessary power headroom reporting requirement from the complete set of SRS ports by identifying the reference port with the smallest insertion loss. Instead of reporting for all ports, the UE only reports for this reference port, significantly reducing the complexity of power headroom reporting while the network compensates by using insertion loss difference information to infer other ports' power headroom.
3Ease of manufacture
If insertion losses are not compensated, then UE implementation is simplified, but downlink scheduling accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the UE reports both power headroom information and insertion loss difference information to the network. This feedback enables the network to compensate for insertion losses in receive-only antennas when performing downlink channel estimation, thereby improving scheduling accuracy without requiring complex UE implementation for power compensation.
Data Source
AI summary
Various aspects of the present disclosure relate to power headroom reporting for sounding reference signal transmissions. A device (e.g., a user equipment (UE)) transmits (e.g., to a base station) an indication of differences in insertion losses between a reference sounding reference signal (SRS) port and each of one or more additional SRS ports at the device. The device also transmits a power headroom report for less than all SRS ports in a set of SRS ports at the device that include the reference SRS port and the one or more additional SRS ports. This allows the base station to determine the transmit power for each of the SRS ports from only the one power headroom report.