LTE Positioning Subframe Alignment for Interference Reduction
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Solution Overview
Problem
Current positioning solutions in wireless communications systems, such as LTE, face challenges in achieving sufficient positioning accuracy due to insufficient receiver detection sensitivities, particularly in indoor environments and due to non-line-of-sight and multipath propagation issues.
Innovation Solution
The method involves selecting a specific time instance for transmitting positioning subframes across base stations to align them, reducing interference from data symbols and enhancing signal detectability without increasing receiver sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If positioning subframes are transmitted without alignment across base stations, then each base station can operate independently, but positioning accuracy deteriorates due to interference from data symbols and poor signal detectability
Solution Approach 1:
The network node selects and communicates a common time instance to multiple base stations before positioning subframe transmission begins. This preliminary coordination ensures that all base stations transmit positioning subframes at the same time, allowing the UE to measure signals from multiple cells simultaneously without interference from data symbols, thereby improving positioning accuracy
Solution Approach 2:
The invention merges the transmission timing of positioning subframes across multiple base stations by aligning them to a common time instance. This coordination combines the resources of multiple base stations to transmit positioning signals in a synchronized manner, enhancing signal detectability and reducing interference through coordinated operation
2Measurement precision
If receiver sensitivity is increased to improve signal detection in indoor environments, then positioning accuracy improves, but device complexity and power consumption increase
Solution Approach 1:
The invention converts the harmful effect of data symbol interference into a benefit by scheduling positioning subframes during specific time instances when data transmission is minimized or absent. This transforms the interference problem into an opportunity to transmit positioning signals with reduced interference, improving detectability without requiring enhanced receiver sensitivity
Solution Approach 2:
The invention changes the temporal parameter of signal transmission by selecting specific time instances for positioning subframe transmission. This parameter change optimizes the signal-to-interference ratio without modifying the receiver's detection capabilities, achieving improved positioning accuracy through network-side timing coordination rather than receiver-side sensitivity enhancement
Data Source
AI summary
The present invention relates generally to methods and arrangements for positioning in a wireless communications system, such as LTE. In particular, the present invention relates to improving positioning accuracy. The invention provides methods and arrangements for scheduling positioning subframes, i.e. low interference subframes, for allowing aligning of positioning subframes across a number of cells in order to reduce the interference from data symbols of cells in the neighborhood of a cell serving the UE that is performing positioning measurements. A time instance during which transmission of the positioning subframes is to occur in a wireless communications network is selected. The base stations in the wireless communications network are informed about the selected time instance, whereupon the base stations schedule and transmit the positioning subframes based on the selected time instance, whereby the positioning subframes are aligned throughout the network.