Reference Signal Segmentation for Wireless Positioning
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Solution Overview
Problem
Current wireless communication networks face challenges in accurately determining the location of user equipment (UE) due to limited time resolution and accuracy in time of arrival (TOA) measurements, particularly when using narrowband signals that spread transmit power across a wide bandwidth, resulting in poor signal quality and limited positioning accuracy.
Innovation Solution
The UE transmits a reference signal across multiple symbol periods of a subframe on contiguous or non-contiguous subcarriers, allowing for improved time resolution and coherent combining of signals, which enhances the uplink time difference of arrival (U-TDOA) positioning method by maintaining higher transmit power and signal quality across receiver stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If narrowband signals are used for reference signal transmission, then transmit power can be concentrated, but time resolution and positioning accuracy deteriorate
Solution Approach 1:
The reference signal is segmented into multiple transmissions across different symbol periods within a subframe. Each transmission occupies a portion of the bandwidth, and together they cover the entire bandwidth. This segmentation allows the signal to maintain concentrated power per transmission while achieving fine time resolution through multiple measurements.
Solution Approach 2:
The solution moves from a single-dimension narrowband signal to a multi-dimensional approach by transmitting across multiple symbol periods (time dimension) and multiple frequency locations (frequency dimension). This dimensional expansion enables both power concentration and fine time resolution to coexist.
2Measurement precision
If reference signal is transmitted across entire bandwidth in one transmission, then time resolution improves, but signal quality deteriorates due to power spreading
Solution Approach 1:
The bandwidth is segmented into multiple portions, with each transmission covering a specific frequency range. This allows the total bandwidth to be explored for fine time resolution while each individual transmission maintains concentrated power for good signal quality.
Solution Approach 2:
Multiple transmissions are performed continuously across different symbol periods, maintaining the useful action of signal transmission. This continuous action across time and frequency provides both fine time resolution and maintains signal quality through power concentration in each transmission.
3Measurement precision
If multiple transmissions are sent in different symbol periods, then time resolution improves, but device complexity increases
Solution Approach 1:
The reference signal transmissions serve multiple functions simultaneously: they provide fine time resolution for positioning, enable channel estimation, and maintain signal quality. This multi-functionality justifies the increased transmission complexity by delivering multiple benefits from the same transmission structure.
Data Source
AI summary
Techniques for transmitting and receiving a reference signal in a wireless network are described. In one design, a UE may generate multiple transmissions of a reference signal at multiple frequency locations. The UE may send the transmissions of the reference signal in multiple symbol periods of at least one subframe. The UE may send at least two transmissions of the reference signal in each subframe, e.g., one transmission of the reference signal in each symbol period of a subframe. Each transmission of the reference signal may cover a portion of the bandwidth of the reference signal and may be sent on a set of contiguous subcarriers at a particular frequency location. The multiple transmissions of the reference signal may cover the entire bandwidth of the reference signal. A location estimate for the UE may be determined based on time of arrivals (TOAs) of the reference signal measured by multiple receiver stations.