Uplink Scheduling Grant CSI Reporting for CoMP Systems
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Solution Overview
Problem
In the LTE system, especially during CoMP transmission/reception, there is a need to flexibly report aperiodic channel state information to multiple coordinated radio base station apparatuses, as interference levels vary across cells, and existing methods lack the necessary flexibility for efficient communication.
Innovation Solution
The solution involves adding bit information to the uplink scheduling grant to designate the specific radio base station apparatus for reporting aperiodic channel state information, allowing for flexible reporting by including an identification field in the CSI request field, enabling targeted feedback of channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aperiodic channel state information reporting is performed in CoMP transmission/reception, then throughput performance is improved, but flexibility in reporting to multiple base station apparatuses is insufficient
Solution Approach 1:
The CSI request field is segmented into multiple independent bits, where each bit can independently trigger A-CSI reporting for a specific base station apparatus. This allows the system to selectively request channel state information from user terminals for different base station apparatuses within the CoMP set, providing flexible and targeted reporting capability.
Solution Approach 2:
The patent extends the traditional single-dimension CSI request mechanism by adding multiple dimensions through additional bits in the CSI request field. Each bit represents a different dimension of control, enabling independent triggering of A-CSI reporting for different base station apparatuses, thus transforming a scalar control signal into a multi-dimensional control vector.
2Adaptability or versatility
If existing uplink scheduling grant methods are used, then device complexity is reduced, but adaptability to CoMP transmission/reception is insufficient
Solution Approach 1:
The enhanced uplink scheduling grant maintains backward compatibility with existing LTE systems while simultaneously supporting CoMP transmission/reception. The additional bits in the CSI request field serve multiple functions: they can trigger A-CSI reporting for individual base station apparatuses, support various CoMP schemes (e.g., dynamic point selection, coordinated beamforming), and maintain compatibility with non-CoMP operations.
Solution Approach 2:
The patent modifies the uplink scheduling grant by changing specific parameters - adding bits to the CSI request field - rather than fundamentally redesigning the entire grant structure. This parameter change approach allows the system to adapt to CoMP requirements while preserving the core structure and reducing the impact on device complexity.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The present invention is designed to flexibly report aperiodic channel state information to a plurality of radio base station apparatuses to be coordinated, even when coordinated multiple-point (CoMP) transmission/reception is performed. A radio communication system includes: a radio base station apparatus that transmits an uplink scheduling grant, which includes a request field that requests reporting of channel state information from a user terminal, and an identification field that identifies a radio base station apparatus to which aperiodic channel state information should be reported, among a plurality of radio base station apparatuses that perform coordinated multiple-point transmission/reception, to the user terminal, via a downlink control channel; and a user terminal that estimates a channel state with respect to a radio base station apparatus that is designated by a combination of the request field and the identification field, and reports the channel state information to the radio base station apparatus via an uplink shared channel.