Dual CSI Codebooks for Coherent Joint Transmission PMI Reporting
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Solution Overview
Problem
Existing wireless communication technologies face challenges in enhancing coherent joint transmission (CJT) for multi-TRP deployments, particularly in FR1 and FR2 frequency bands, to improve coverage and throughput, especially with non-ideal backhaul conditions.
Innovation Solution
Implementing codebook enhancement methods that include configuring and transmitting/receiving Precoder Matrix Indicators (PMIs) using phase adjustment coefficients across multiple TRPs, utilizing dual codebooks for Channel State Information (CSI) reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual codebooks with phase adjustment coefficients are configured for multi-TRP CSI reporting, then coherent joint transmission performance and coverage are improved, but system complexity and codebook configuration overhead increase
Solution Approach 1:
The patent divides the codebook into two separate codebooks: a first codebook for CSI reporting to a first TRP and a second codebook for CSI reporting to a second TRP. Each codebook contains precoder matrices with phase adjustment coefficients specific to its corresponding TRP. This segmentation allows independent optimization of each codebook for its specific TRP while maintaining overall system coherence, thereby improving CJT performance without requiring a single overly complex unified codebook.
Solution Approach 2:
The patent applies local quality by assigning different phase adjustment coefficients to different TRPs based on their specific channel conditions. The first codebook uses phase adjustment coefficients optimized for the first TRP's backhaul and wireless conditions, while the second codebook uses coefficients optimized for the second TRP. This localized optimization enables each TRP to operate at its optimal performance point, improving overall system reliability while avoiding the complexity of a uniform global codebook.
2Productivity
If multiple TRPs transmit signals with coordinated phase adjustment, then coverage and throughput are enhanced, but backhaul synchronization requirements and system complexity increase
Solution Approach 1:
The patent implements dynamics by allowing the phase adjustment coefficients in each codebook to be dynamically selected based on current channel conditions. The UE can choose different phase adjustment coefficients from predefined sets in each codebook depending on the instantaneous signal quality and backhaul conditions. This dynamic adaptation enables the system to maintain high throughput under varying conditions without requiring rigid, pre-synchronized backhaul configurations, thereby reducing synchronization complexity.
Solution Approach 2:
The patent changes the parameter of phase adjustment coefficients independently for each TRP based on local channel conditions. Instead of requiring all TRPs to use identical phase settings, the system allows different phase adjustment coefficients to be applied to different TRPs. This parameter differentiation improves throughput by optimizing each TRP's transmission independently while reducing the need for complex backhaul synchronization across all TRPs.
3Reliability
If phase adjustment coefficients are applied to precoder matrices in codebooks, then coherent transmission is improved, but codebook size and information reporting overhead increase
Solution Approach 1:
The patent applies partial action by including phase adjustment coefficients only in specific codebooks (first and second codebooks) rather than in all possible codebooks. The phase adjustment is applied selectively to the precoder matrices that are actually used for the current transmission configuration. This partial application improves coherent transmission quality for the active TRPs while avoiding the overhead of including phase adjustment information in unnecessary codebooks, thereby reducing overall information reporting overhead.
Data Source
AI summary
Methods and apparatus of codebook enhancement for coherent joint transmission are disclosed. The apparatus includes: a receiver that receives a configuration signalling for a first codebook and a second codebook, wherein the first codebook is for Channel State Information (CSI) reporting to a first transmitting-receiving entity, and the second codebook is for CSI reporting to a second transmitting-receiving entity; a processor that determines a Precoder Matrix Indicator (PMI) based on the second codebook comprising one or more phase adjustment coefficients; and a transmitter that transmits the PMI in reporting of CSI.