Base Station Offset Values for MU-MIMO Cell Selection
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Solution Overview
Problem
Current cell selection methods in wireless communication systems do not effectively consider the differences between various precoding schemes, particularly impacting received signal power and spectral efficiency in heterogeneous networks, especially between linear and nonlinear MU-MIMO schemes.
Innovation Solution
A base station apparatus and terminal apparatus configuration that transmits and adds multiple offset values to the reference signal based on supported precoding schemes, allowing for proper setting of the offset value according to the MU-MIMO scheme, with the option for linear and nonlinear precoding, to enhance cell selection and spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If cell range expansion (CRE) with offset value addition is applied to pico base station apparatus, then the cell radius of pico base station apparatus is increased and the coverage area is expanded, but the received power difference between macro and pico base stations is not sufficiently considered leading to suboptimal cell selection
Solution Approach 1:
The invention changes the offset value parameter dynamically based on the MU-MIMO scheme type (linear or nonlinear precoding). The base station determines which MU-MIMO scheme is supported and notifies the terminal of an appropriate offset value, allowing the system to adapt the CRE parameter to match the capabilities of both base station and terminal, thereby improving cell selection accuracy while maintaining expanded coverage.
2Productivity
If multiple offset values are transmitted for different precoding schemes, then the spectral efficiency is improved through optimal cell selection, but the signaling overhead and system complexity increase
Solution Approach 1:
The invention implements a dynamic mechanism where the base station determines the MU-MIMO scheme capability and selectively notifies the terminal of the appropriate offset value. This dynamic adaptation allows the system to maintain multiple offset values for different precoding schemes without permanently increasing complexity, as the system activates only the necessary offset value based on current capabilities.
Solution Approach 2:
The invention segments the offset value notification process by creating separate offset values for linear MU-MIMO and nonlinear MU-MIMO schemes. The base station divides the notification process into determining terminal capabilities, selecting the appropriate offset value segment, and notifying only the relevant offset value, thereby managing complexity through structured segmentation.
3Reliability
If the base station apparatus determines and notifies the offset value based on MU-MIMO scheme support, then the cell selection performance is optimized for the specific precoding scheme, but the processing time and signaling overhead increase
Solution Approach 1:
The invention performs preliminary determination of MU-MIMO scheme support and offset value selection during the connection establishment phase or before handover decisions. By determining the appropriate offset value in advance rather than in real-time during cell selection, the system optimizes cell selection performance while minimizing the time loss during actual cell selection operations.
Data Source
AI summary
The present invention provides a technology that sets an offset value with respect to a received power of a reference signal from each of base station apparatuses, taking into consideration a difference between precoding schemes, in a wireless communication system that supports multiple different precoding schemes. The base station apparatus according to the present invention communicates with at least one of terminal apparatuses using the multiple different precoding schemes. The base station apparatus according to the present invention includes a transmission unit that transmits to the terminal apparatus multiple offset values that are to be added by the terminal apparatus to the received power of the reference signal from the base station apparatus, in which the multiple offset values correspond to the multiple precoding schemes, respectively.