Uplink Spatial Relation Using TCI States for Lower NR Overhead
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Solution Overview
Problem
The high implementation cost and overhead of higher layer parameters in determining spatial relation and power control parameters for uplink signals in wireless communications, particularly in 5G new radio (NR), are exacerbated by the finite controllable phases of analog phase shifters and constant modulus constraints in antenna arrays.
Innovation Solution
A wireless communication method that determines spatial relation and power control parameters for uplink signals without relying on higher layer parameters, using transmission configuration indicators (TCI) and quasi-co-location (QCL) types to align beam behavior between downlink and uplink signals, and utilizes MAC control elements to update path-loss reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher layer parameters are used to configure spatial relation and power control for uplink signals, then beam alignment and power control can be achieved, but the overhead of higher layer parameters increases
Solution Approach 1:
The patent applies the copying principle by using downlink TCI states as templates to define uplink spatial relation information. Instead of configuring separate uplink beam parameters, the system copies downlink TCI state configurations (including QCL relationships and spatial parameters) to establish uplink spatial relations. This reduces uplink configuration overhead while maintaining beam alignment reliability through proven downlink beam configurations.
Solution Approach 2:
The patent implements universality by making TCI states serve dual purposes for both downlink and uplink transmissions. The same TCI state configurations that manage downlink beamforming are reused to determine uplink spatial relations and power control parameters. This multi-functional approach eliminates redundant parameter sets and reduces overall signaling overhead while maintaining reliable beam management for both directions.
2Ease of manufacture
If analog phase shifters are used to implement beam-forming, then implementation cost is reduced, but the number of controllable phases becomes finite and constant modulus constraints are placed on antenna elements
Solution Approach 1:
The patent applies parameter changes by utilizing the finite phase states of analog phase shifters as a design constraint rather than a limitation. The beamforming system is configured to operate with discrete phase values (e.g., 2-bit or 3-bit quantized phases) and constant modulus constraints, optimizing beamforming weights within these restricted parameter spaces. This approach maintains low implementation cost while achieving sufficient beam alignment through optimized discrete phase configurations.
Solution Approach 2:
The patent implements partial action by using a subset of available antenna elements or phase states to achieve the required beamforming performance. Instead of utilizing all possible continuous phase values, the system employs a limited number of discrete phase levels that provide adequate beam alignment for the specific deployment scenario, thereby reducing hardware complexity and cost while maintaining acceptable adaptability.
3Reliability
If massive MIMO with up to 1024 antenna elements is adopted, then beam alignment and antenna gain are improved, but propagation loss at extremely high frequencies remains a challenge
Solution Approach 1:
The patent applies preliminary action by performing beam alignment using downlink transmissions before uplink data transmission. The gNB transmits downlink reference signals with specific TCI states that establish beam directions, allowing the UE to measure and determine corresponding uplink spatial relations in advance. This preliminary beam alignment ensures that when uplink transmission occurs, the beams are already optimized to compensate for high-frequency propagation losses, improving link reliability without requiring real-time adjustment during data transmission.
Data Source
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AI summary
Method, systems and devices for determining spatial relation and power control parameter for uplink signals. The method for use in a wireless terminal comprises determining at least one of at least one power control parameter or spatial relation for a first uplink signal on a first component carrier, and transmitting, to a wireless network node, the first uplink signal on the first component carrier based on at least one of determined at least one power control parameter or determined spatial relation.