Multi-TRP Constellation Diversity for URLLC Reliability
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Solution Overview
Problem
Current Ultra-Reliable Low-Latency Communication (URLLC) in New Radio (NR) Release 15 faces limitations in transmission reliability due to excessive repetitions and delay implications, necessitating further enhancements for improved performance.
Innovation Solution
The method involves determining multiple repetitions of a data payload, with each repetition using a different constellation mapping and resource allocation, and transmitting these using multi-dimensional modulation schemes across separate or shared resources by multiple TRPs to enhance transmission reliability and diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple repetitions of data payload are transmitted using the same constellation mapping, then transmission reliability is improved through redundancy, but diversity gain is limited and detection capability does not maximize
Solution Approach 1:
The patent applies parameter changes by varying the constellation mapping for each repetition of the data payload. Instead of using the same constellation mapping for all repetitions, the system changes the modulation parameters (constellation type, mapping pattern) across different repetitions transmitted from multiple TRPs. This enables the receiver to leverage diversity in detection capabilities while maintaining transmission reliability through redundant transmissions.
2Reliability
If beam link failure occurs at the primary coordinating TRP, then control information transmission is disrupted, but transmission at other TRPs should continue without interruption
Solution Approach 1:
The patent applies segmentation by dividing the control information transmission across multiple independent TRPs, each capable of autonomous operation. The data payload is segmented into multiple repetitions, with each repetition transmitted from a different TRP using independent constellation mappings. This segmentation ensures that beam link failure at one TRP does not affect transmissions from other TRPs, maintaining overall transmission continuity.
3Adaptability or versatility
If WTRU performs blind detection on multiple receive NR-PDCCH, then scheduling flexibility increases, but the effective size of search space increases and complexity rises
Solution Approach 1:
The patent applies local quality by assigning different constellation mappings to different TRPs and their respective PDCCH/PDSCH transmissions. Each TRP uses a locally optimized constellation mapping suitable for its transmission characteristics and channel conditions. This allows the WTRU to perform blind detection on multiple PDCCH with reduced complexity, as each TRP's transmission has distinct local characteristics that facilitate identification and decoding.
Data Source
AI summary
A method performed by a transmit/receive point (TRP) for enhancing transmission reliability may include transmitting information indicating at least a first constellation to be used for modulating a transmission. The method includes transmitting, in a first time interval, a first repetition of a data payload. The transmitted first repetition of the data payload includes a set of coded bits that is modulated according to the indicated constellation. The method includes transmitting, in a second time interval, a second repetition of the data payload. The first time interval is a slot within a repetition window and the second time interval is a later slot within the repetition window. The second repetition includes a set of coded bits that is modulated according to a second constellation. The first constellation and the second constellation may be different and vary respectively based on repetition indices corresponding to the first repetition and the second repetition.