Wireless Resource Block Allocation for Low-Overhead CSI Reporting
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Solution Overview
Problem
The increase in codebook size for FD-MIMO systems leads to increased terminal computation and feedback overhead, causing burden on terminals, particularly in periodic and aperiodic channel state reports, and resource allocation inefficiencies in LTE/LTE-A systems with short transmission time intervals.
Innovation Solution
A method for efficient aperiodic CSI-RS configuration and transmission, along with resource allocation techniques for downlink and uplink data transmission, is implemented to reduce overhead and improve channel state information acquisition, allowing terminals to accurately measure and report channel states using aperiodic CSI-RSs and optimize resource block group allocation based on bandwidth and configuration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If codebook size is increased to support FD-MIMO with 16 to 32 non-precoded CSI-RSs, then channel state information accuracy is improved, but terminal computation overhead and feedback overhead are increased
Solution Approach 1:
The codebook is divided into multiple codebook subsets, each corresponding to different channel conditions or antenna configurations. The terminal only needs to compute and report PMI within the activated subset, reducing overall computation overhead while maintaining accurate CSI reporting capability across the full codebook space.
Solution Approach 2:
The codebook subset activation is dynamically adjusted based on channel conditions, terminal capability, and system configuration. The network can activate different subsets adaptively, allowing the terminal to perform computations only on relevant subsets, thereby reducing computation overhead while preserving CSI accuracy when needed.
2Measurement precision
If codebook size is increased to support FD-MIMO with 16 to 32 non-precoded CSI-RSs, then channel state information accuracy is improved, but feedback overhead is increased
Solution Approach 1:
The PMI feedback is segmented into subset-specific indicators. Instead of reporting PMI from the entire large codebook, the terminal reports a subset indicator combined with a reduced-range PMI, significantly reducing feedback overhead while maintaining the ability to accurately represent channel state information across the full codebook space.
Solution Approach 2:
The codebook subset activation mechanism acts as an intermediary between the large codebook and the feedback channel. By pre-selecting and activating specific subsets, the system reduces the dimensionality of the feedback requirement while preserving the essential channel information through the subset selection itself.
3Ease of operation
If periodic channel state report configuration is simplified, then ease of operation is improved, but adaptability to different channel conditions is reduced
Solution Approach 1:
While maintaining simple periodic reporting configuration, the system dynamically activates different codebook subsets based on channel conditions and terminal reports. This allows the simple configuration to adapt to varying channel conditions without requiring complex reconfiguration, achieving both ease of operation and adaptability.
Solution Approach 2:
The system performs preliminary codebook subset activation based on initial channel assessments or terminal capabilities before periodic reporting begins. This preliminary action prepares the system to handle different channel conditions using pre-configured subsets, maintaining configuration simplicity while enabling adaptability through pre-established options.
Data Source
AI summary
Disclosed are methods performed by a base station in a wireless communication system including identifying a number of orthogonal frequency division multiplexing (OFDM) symbols for a terminal; identifying downlink control information (DCI) format for the terminal; generating DCI for the terminal based on a resource allocation type and resource block group for data transmission of the terminal, wherein the resource allocation type is identified based on the DCI format; transmitting, to the terminal, the DCI; and transmitting, to the terminal, data corresponding to the DCI. The resource block group includes consecutive virtual resource blocks and a number of the consecutive virtual resource blocks is determined based on a size of a bandwidth and a configuration information by a higher layer signaling.