Narrowband Positioning Reference Signal Mapping for IoT Accuracy
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Solution Overview
Problem
IoT terminals, which primarily handle small data and operate on narrowbands, face degraded position estimation accuracy due to their limited bandwidth capabilities.
Innovation Solution
The implementation of a base station apparatus and location server system that enhances position estimation accuracy by using narrowband positioning reference signals (NPRS) with specific mapping strategies, such as transmitting NPRS in OFDM symbols other than those used for NRS, and varying NPRS between positive and negative signs in a prescribed pattern to mitigate interference and increase frequency density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional PRS is used for positioning, then position estimation accuracy can be maintained in wideband systems, but position estimation accuracy degrades in narrowband systems
Solution Approach 1:
The patent changes the bandwidth parameter of the positioning reference signal from wideband (traditional PRS) to narrowband (NPRS), making it suitable for narrowband IoT terminals while maintaining position estimation accuracy. The NPRS is configured with a bandwidth of 1.08 MHz or less, specifically adapted for narrowband operation.
Solution Approach 2:
The patent applies different signal qualities to different frequency regions by concentrating the positioning reference signal energy within a narrow bandwidth region. This local concentration of signal energy in the narrowband region improves the signal-to-noise ratio and measurement accuracy for narrowband terminals.
2Productivity
If NPRS is transmitted in the same OFDM symbols as NRS, then resource utilization is efficient, but interference between NRS and NPRS degrades measurement accuracy
Solution Approach 1:
The patent segments the time-frequency resources by separating NRS and NPRS transmissions into different OFDM symbols. This segmentation eliminates interference between the two signals while maintaining efficient resource utilization through dedicated resource allocation for each signal type.
Solution Approach 2:
The patent introduces an intermediary resource allocation mechanism that mediates between NRS and NPRS transmissions. By allocating separate OFDM symbols for each signal, the system acts as an intermediary to prevent direct interference while maintaining overall resource efficiency.
3Measurement precision
If NPRS frequency density is increased to improve accuracy, then position estimation accuracy improves, but interference from adjacent frequencies increases
Solution Approach 1:
The patent transitions from frequency-domain density increase to time-domain separation by allocating NPRS to specific OFDM symbols. This dimensional change from frequency to time domain allows high frequency density within the narrowband while avoiding adjacent frequency interference through temporal isolation.
Data Source
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AI summary
To provide a base station apparatus, a terminal apparatus, a location server, and a communication apparatus that are capable of improving position estimation accuracy. A physical signal generating unit configured to generate first positioning reference signal and second positioning reference signal, and a transmitter configured to transmit the first positioning reference signal and the second positioning reference signal to a terminal apparatus are provided. The first positioning reference signal is mapped on one resource block and the second positioning reference signal is mapped on at least six resource blocks. The resource block is constituted of prescribed subcarriers in a frequency domain. A maximum v number of consecutive subframes on which the first positioning reference signal is transmitted is larger than a maximum number of consecutive subframes on which the second positioning reference signal is transmitted.