Type II Port Selection Codebook Extension for Higher Rank Transmission
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Solution Overview
Problem
Current Type II port selection codebooks in New Radio (NR) are limited in supporting higher rank transmissions, particularly in utilizing angle-delay reciprocity of the propagation channel.
Innovation Solution
The proposed method extends the Type II port selection codebook by configuring beamformed SD and FD ports, allowing for CSI reporting that incorporates angle-delay reciprocity, thereby enhancing support for higher rank transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Type II port selection codebook is extended for higher rank transmission, then transmission performance is improved, but reporting overhead increases
Solution Approach 1:
The codebook extension is segmented by rank, where each rank has its specific codebook configuration. The Type II port selection codebook is divided into different codebook subsets corresponding to different transmission ranks (rank 1-2 from Rel-15/16, and extended rank 3-8 in this patent). This segmentation allows the system to select only the necessary codebook subset based on current transmission requirements, avoiding unnecessary reporting overhead while maintaining improved transmission performance for higher ranks.
Solution Approach 2:
The patent applies partial action by selectively extending the codebook only for higher rank transmissions (rank 3-8) rather than modifying the entire codebook structure. For lower ranks (1-2), the original Rel-15/16 Type II port selection codebook is maintained. This partial extension approach improves transmission performance for higher ranks while minimizing impact on reporting overhead for lower rank transmissions.
2Measurement precision
If angle-delay reciprocity is utilized for CSI reporting, then channel estimation accuracy is improved, but UE complexity increases
Solution Approach 1:
The patent makes the Type II port selection codebook universal by designing it to support multiple transmission ranks (rank 1-8) within a unified framework. The same codebook structure and port selection mechanism are used across all ranks, with the difference being the number of layers and corresponding precoding matrices. This universality allows the gNB to estimate channels accurately using angle-delay reciprocity across all ranks while avoiding the need for separate complex processing mechanisms for each rank, thereby controlling UE complexity.
Solution Approach 2:
The patent changes key parameters of the codebook extension based on transmission rank requirements. Specifically, the number of codebook subsets, the number of ports, and the dimension of precoding matrices are adjusted according to the rank. For example, higher ranks use more codebook subsets and larger matrix dimensions. These parameter changes enable accurate channel estimation for different ranks while allowing the system to adapt to varying complexity requirements.
Data Source
AI summary
A terminal for performing Channel State Information (CSI) reporting for type II port selection codebook includes a receiver that receives beamformed CSI reference signal (RS) ports comprising spatial domain (SD) beams and frequency domain (FD) base. In addition, the terminal includes a processor that, using higher layer signaling, configures a number of SD beam selection and a number of FD base selection, and selects a first value from a first set of values for the number of SD beam selection and a second value from a second set of values for the number of FD base section. The terminal further includes a transmitter that transmits the first value and the second values.