Flexible Reference Signal Bandwidth for Interference-Limited Positioning
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Solution Overview
Problem
Current LTE positioning methods face challenges due to low signal-to-interference ratios and insufficient signal coverage, particularly in synchronized networks with high data loads, leading to positioning coverage problems and inefficient resource utilization.
Innovation Solution
Implementing a flexible reference signal (RS) transmission bandwidth that is smaller than the system bandwidth, allowing for better interference coordination and efficient radio resource utilization, which enables improved RS measurements and positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals are transmitted over the entire system bandwidth, then measurement coverage is improved, but interference increases and resource utilization decreases
Solution Approach 1:
The patent divides the system bandwidth into multiple sub-bands and transmits reference signals only in selected sub-bands rather than the entire bandwidth. This segmentation reduces interference while maintaining adequate measurement coverage by distributing reference signal transmissions across different frequency segments.
Solution Approach 2:
The patent applies different transmission strategies to different sub-bands within the system bandwidth. By selectively activating reference signal transmission in specific sub-bands based on interference conditions and measurement requirements, the system optimizes local quality in each frequency region while reducing overall interference.
2Measurement precision
If reference signals are transmitted frequently to meet positioning accuracy requirements, then positioning accuracy improves, but resource utilization decreases
Solution Approach 1:
The patent implements periodic reference signal transmissions in a time-division manner, where reference signals are sent in specific sub-frames rather than continuously. This periodic action maintains positioning accuracy by providing sufficient measurement opportunities while reducing resource consumption by leaving gaps between transmissions.
Solution Approach 2:
The patent transmits reference signals in only a portion of the available time resources (specific sub-frames) rather than continuously. This partial action provides sufficient measurement data for accurate positioning while avoiding the excessive resource consumption that would result from continuous transmissions.
3Loss of energy
If the reference signal bandwidth is reduced to improve resource utilization, then resource efficiency improves, but measurement coverage decreases
Solution Approach 1:
The patent compensates for reduced bandwidth in the frequency dimension by utilizing the time dimension more effectively. Reference signals are transmitted across multiple sub-frames and sub-bands, distributing measurements over time and frequency segments to maintain adequate coverage area despite narrower instantaneous bandwidth.
Solution Approach 2:
The patent performs measurements across multiple reference signal transmissions in different sub-frames and sub-bands, accumulating measurement data over time. This preliminary action in multiple time-frequency segments compensates for the reduced coverage in any single transmission, maintaining overall measurement coverage.
Data Source
AI summary
The present invention relates to methods and apparatus in a RBS and a UE for reference signal (RS) measurements in an OFDM system, that enable having a configurable RS transmission bandwidth which is smaller than the system bandwidth. This allows for better interference coordination of RS, which in turn improves the UE RS measurements used for different services such as positioning. The RBS retrieves the RS transmission bandwidth, determines a RS measurement bandwidth based on this RS transmission bandwidth, and transmits the determined bandwidth to the UE. The UE receives the RS measurement bandwidth and measures the RS in a bandwidth determined based on the received measurement bandwidth and the UE capability.