CSI-RS Resource Element Grouping for Interference Reduction
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Solution Overview
Problem
Wireless communication systems face challenges in efficiently utilizing channel state information reference signals (CSI-RS) due to bandwidth constraints and interference from other reference signals, leading to reduced transmission resources for data and control signals.
Innovation Solution
The method involves identifying available data resource elements (REs) in a subframe and assigning them in groups to ensure all assigned REs within a group are close in time and frequency, resulting in at least one ungrouped RE, which can be used for CSI-RS transmissions, thereby optimizing resource allocation and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference signals are transmitted to maintain or improve wireless system performance, then channel estimation accuracy and system reliability are improved, but bandwidth available for data transmission is reduced
Solution Approach 1:
The patent segments reference signals into different types (CSI-RS, CRS, etc.) with different functions and transmission patterns. CSI-RS is specifically designed for channel state information acquisition in MIMO systems, while other reference signals serve different purposes. This segmentation allows optimized resource allocation for each signal type, improving overall spectral efficiency while maintaining necessary channel estimation capabilities.
Solution Approach 2:
The patent utilizes multiple dimensions (time, frequency, spatial) to transmit reference signals and data simultaneously. By employing MIMO technology with multiple antennas, the system can transmit CSI-RS on certain antenna ports while transmitting data on other antenna ports or resource elements, effectively increasing the available bandwidth for data transmission without compromising channel estimation accuracy.
2Measurement precision
If new reference signals are assigned transmission resources, then channel state information acquisition is improved, but transmission resources for pre-existing reference signals or data signals are reduced
Solution Approach 1:
The patent applies local quality by assigning different resource allocation patterns to different reference signal types based on their specific requirements. CSI-RS uses specific resource element patterns that are optimized for MIMO channel estimation, while other reference signals use different patterns. This localized optimization ensures that each reference signal gets the appropriate resources without unnecessarily reducing resources available for other signals or data.
Solution Approach 2:
The patent designs CSI-RS to serve multiple functions: channel estimation for MIMO, interference measurement, and feedback generation. By making this reference signal multi-functional, the system reduces the need for separate dedicated signals for each function, thereby conserving transmission resources while maintaining or improving measurement precision.
3Productivity
If reference signals are transmitted using existing transmission resources, then resource utilization efficiency is improved, but interference with legacy user equipment expecting data transmissions increases
Solution Approach 1:
The patent implements dynamic resource allocation where the transmission of CSI-RS is controlled based on system conditions and legacy UE presence. The system can dynamically adjust which resource elements are used for CSI-RS versus data transmission, and can dynamically switch between different transmission modes (e.g., rate matching around CSI-RS resources versus puncturing). This dynamic approach allows high resource utilization when legacy UEs are absent while minimizing interference when they are present.
Data Source
AI summary
In a wireless communication system, from available data resource elements (REs) in a subframe, REs are assigned to transmissions of a reference signal, thereby resulting in a plurality of remaining data REs. Furthermore, REs from the plurality of remaining data REs are assigned for data transmission to a wireless device in groups of a predetermined number of REs such that all assigned data REs within a group are within a predetermined number of symbols of each other in time domain and within a second predetermined number of subcarriers of each other in frequency domain, thereby resulting in at least one ungrouped RE.