PT-RS Indication in Multi-User Superposition Transmission
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Solution Overview
Problem
In next-generation 5G wireless communication systems, phase noise in high-frequency bands causes common phase error and inter-carrier interference, which can be mitigated using Phase Tracking Reference Signals (PT-RS), but determining their presence and patterns is challenging, especially for Multi-User Superposition Transmission (MUST) scenarios where UEs have varying Signal-to-Interference-Plus-Noise Ratios (SINR).
Innovation Solution
The solution involves determining the presence and patterns of PT-RS based on Modulation and Coding Schemes (MCS) and amplitude weights, with mechanisms such as Far-UE indicators in Downlink Control Information (DCI), joint coding of MCS and Far-UE states, and blind decoding for UEs with small modulation orders, to effectively manage PT-RS transmission and compensation for phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Phase Tracking Reference Signals (PT-RS) are used to mitigate phase noise in high-frequency bands, then phase noise compensation accuracy is improved, but determining PT-RS presence and patterns becomes more challenging in MUST scenarios
Solution Approach 1:
The patent applies preliminary action by pre-configuring PT-RS presence indication information through higher-layer signaling (RRC configuration) before actual transmission. This allows the UE to have advance knowledge of PT-RS configuration parameters, making the detection and measurement process more straightforward during actual reception.
Solution Approach 2:
The patent implements feedback mechanisms where the gNB transmits PT-RS presence indication information to the UE, and the UE uses this information to determine whether to expect PT-RS in upcoming transmissions. This feedback loop resolves the determination difficulty by providing explicit guidance rather than requiring complex blind detection.
2Reliability
If PT-RS transmission is configured for all UEs, then phase noise compensation is available for all users, but signaling overhead and system complexity increase
Solution Approach 1:
The patent applies local quality by configuring PT-RS presence indication information specifically for UEs that require it (e.g., Far-UEs in MUST scenarios or UEs experiencing significant phase noise). Instead of universal configuration, only affected UEs receive PT-RS presence indication through RRC signaling, reducing overall system complexity while maintaining reliability where needed.
Solution Approach 2:
The patent implements dynamic configuration where PT-RS presence indication is adaptively provided to UEs based on their specific conditions (SINR, distance, modulation order). The gNB dynamically decides which UEs receive PT-RS configuration information, allowing the system to balance reliability and complexity based on real-time channel conditions.
3Ease of operation
If blind decoding is used for UEs with small modulation orders, then PT-RS determination is simplified, but decoding complexity and processing time increase
Solution Approach 1:
The patent applies partial action by using blind decoding only for UEs with small modulation orders (e.g., QPSK) where the overhead of explicit signaling would be disproportionate. For these specific cases, simplified blind decoding is performed without full PT-RS presence indication, reducing processing time while maintaining operational simplicity.
Solution Approach 2:
The patent changes the determination approach based on modulation order parameters. For UEs with small modulation orders, blind decoding is enabled as a simplified mode. This parameter-based differentiation allows the system to switch between full PT-RS indication and blind decoding modes, optimizing the balance between simplicity and processing time for different UE conditions.
Data Source
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AI summary
Described is an apparatus of an Evolved Node-B (eNB) operable to communicate with a User Equipment (UE) on a wireless network. The apparatus may comprise a first circuitry and a second circuitry. The first circuitry may be operable to determine a presence of a Phase Tracking Reference Signal (PT-RS) and a density of the PT-RS. The second circuitry may be operable to process the PT-RS. The second circuitry may also be operable to process a transmission in a Multi-User Superposition Transmission (MUST) operation in accordance with the PT-RS.