Wireless Resource Allocation for Shortened-TTI Coexistence
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Solution Overview
Problem
In FD-MIMO systems, the increase in codebook size leads to increased PMI overhead, terminal computation overhead, and feedback overhead, causing terminal burden, particularly in periodic and aperiodic channel state reports, and the need for efficient resource allocation in LTE/LTE-A systems with shortened TTI.
Innovation Solution
A method and apparatus for configuring aperiodic CSI-RS transmission and reception, allowing efficient channel state information acquisition and resource allocation, enabling coexistence of shortened-TTI and normal-TTI terminals in the same system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If codebook size is increased to support 16 to 32 non-precoded CSI-RSs in FD-MIMO, then channel state measurement precision is improved, but PMI overhead and terminal computation overhead are increased
Solution Approach 1:
The patent segments the codebook into multiple codebook subsets, each corresponding to different channel conditions or antenna configurations. The terminal only needs to report PMI for the relevant subset rather than the entire codebook, reducing feedback overhead while maintaining measurement precision for the active subset.
Solution Approach 2:
The patent implements dynamic codebook subset selection where the base station adapts the codebook configuration based on channel quality indicators and terminal capabilities. The codebook size and structure change dynamically depending on operating conditions, optimizing the balance between measurement precision and feedback overhead.
2Measurement precision
If codebook size is increased to support 16 to 32 non-precoded CSI-RSs in FD-MIMO, then channel state measurement precision is improved, but terminal computation overhead is increased
Solution Approach 1:
By dividing the large codebook into smaller subsets, the terminal only performs computations for the relevant subset based on channel conditions. This segmentation reduces the computational complexity from O(N) where N is the total codebook size to O(n) where n is the subset size, while maintaining precision through selective subset activation.
Solution Approach 2:
The terminal performs partial codebook evaluation by only computing PMI for the most likely codebook subset based on channel quality metrics. This partial action approach avoids exhaustive computation across the entire codebook while ensuring sufficient measurement precision for the active transmission configuration.
3Measurement precision
If periodic channel state report is used with increased codebook size, then channel state information accuracy is improved, but feedback overhead is increased
Solution Approach 1:
The patent segments feedback into periodic and aperiodic components, where periodic feedback uses compressed codebook subset indices and aperiodic feedback provides detailed CSI when needed. This segmentation allows accurate channel state information to be transmitted efficiently by using concise periodic updates supplemented by detailed aperiodic reports.
Solution Approach 2:
The codebook structure is designed to serve multiple functions: it supports both periodic compressed feedback and aperiodic detailed feedback, and adapts to different channel conditions. This multi-functionality allows the same codebook infrastructure to provide accurate CSI while optimizing feedback overhead through mode selection.
4Speed
If shortened-TTI is implemented for latency reduction, then transmission speed is improved, but resource allocation complexity is increased due to coexistence with normal-TTI terminals
Solution Approach 1:
The patent segments the system into shortened-TTI and normal-TTI domains with separate resource allocation mechanisms. Shortened-TTI resources are allocated independently for latency-critical traffic, while normal-TTI resources handle other traffic. This segmentation allows high-speed transmission for short TTI without complicating overall resource management through clear domain separation.
Solution Approach 2:
The patent introduces an intermediary resource allocation layer that coordinates between shortened-TTI and normal-TTI allocations. This intermediary mechanism resolves conflicts and optimizes resource distribution across different TTI types, reducing the overall complexity by providing a unified coordination point rather than requiring complex direct interactions between different TTI domains.
Data Source
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AI summary
The present invention relates to a communication technique, which is a convergence of IoT technology and 5G communication system for supporting higher data transmission rate beyond 4G system, and a system for same. The present invention can be applied to smart services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retail businesses, security- and safety-related services and the like) on the basis of 5G communication technology and IoT-related technology. The present invention provides a resource allocation method by a base station comprising the steps of: comparing a transmission time interval (TTI), which is for transmitting data to a terminal, with a preconfigured transmission time interval reference value; if the transmission time interval for the data transmission is shorter than the transmission time interval reference value, determining a resource allocation type for showing frequency resources allocated for the data transmission, and generating control information on the basis of the determined resource allocation type.