MTC Device Positioning Using CRS and SSS Signals
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Solution Overview
Problem
Machine Type Communication (MTC) devices face challenges in achieving accurate positioning due to their limited bandwidth operation, which restricts their ability to utilize positioning reference signals effectively, leading to poor positioning accuracy compared to conventional mobile communication devices.
Innovation Solution
The method involves utilizing common reference signal (CRS), primary synchronization signal (PSS), and secondary synchronization signal (SSS) transmissions from base stations to improve positioning accuracy of MTC devices, leveraging these signals for positioning determination instead of or in addition to traditional Positioning Reference Signals (PRS), which are more prevalent in wider bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If MTC devices operate in narrow bandwidth (1.4 MHz) to reduce power consumption and cost, then device complexity and power usage are reduced, but positioning accuracy deteriorates due to limited utilization of positioning reference signals
Solution Approach 1:
The patent makes existing reference signals (CRS, PSS, SSS) serve dual purposes: their primary functions for data transmission and synchronization, plus an additional positioning function. This allows MTC devices to perform positioning using signals already present in the system, without requiring dedicated positioning signals, thereby maintaining narrow bandwidth operation while improving positioning accuracy
Solution Approach 2:
The patent changes the parameters used for positioning measurements by utilizing signals with higher periodicity (CRS every subframe, PSS/SSS every 5 subframes) instead of relying solely on PRS signals. This parameter change in signal selection and measurement timing enables accurate positioning within the constrained 1.4 MHz bandwidth
2Area of stationary object
If MTC devices utilize only a small portion of PRS transmissions within 1.4 MHz bandwidth, then bandwidth requirements are reduced, but positioning accuracy deteriorates due to limited signal availability
Solution Approach 1:
The patent enables existing reference signals (CRS, PSS, SSS) to serve dual purposes: their primary functions for data transmission and synchronization, plus an additional positioning function. This allows MTC devices to perform positioning using signals already present in the system, without requiring dedicated positioning signals, thereby maintaining narrow bandwidth operation while improving positioning accuracy
Solution Approach 2:
The patent merges positioning functionality with existing reference signal transmissions. Instead of separating positioning signals from other signals, it combines positioning measurements with CRS, PSS, and SSS signals that are already being transmitted for other purposes, thereby utilizing the full available bandwidth efficiently for multiple functions simultaneously
3Measurement precision
If CRS and synchronization signals are used for positioning instead of PRS, then positioning accuracy is improved through higher periodicity and reduced interference, but signal selection complexity increases
Solution Approach 1:
The patent enables MTC devices to self-select and self-process appropriate reference signals (CRS, PSS, SSS) for positioning measurements based on their capabilities and current conditions. The device autonomously determines which signals to use and performs the measurements without requiring complex network coordination or additional signaling overhead
Solution Approach 2:
The patent allows MTC devices to perform positioning measurements using partial signal sets (choosing from CRS, PSS, SSS based on availability and conditions) rather than requiring all signal types. This partial action approach reduces processing complexity while still achieving improved positioning accuracy through the higher periodicity and reduced interference characteristics of these signals
Data Source
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AI summary
Embodiments improve User Equipment (UE) positioning accuracy in a mobile communication system (200) by providing for a UE (204, 206) configured to listen for Positioning Reference Signal (PRS) transmissions within an operating bandwidth around Direct Current (DC) sub-carrier and at least one non-PRS transmission including, for example, a CRS or PSS/SSS; receiving, at the UE (204, 206), PRS and non-PRS(s) transmissions transmitted from base stations (201) within the operating bandwidth; performing, at the UE (204, 206), Time of Arrival (TOA) measurements for each of the plurality of base stations (201), wherein the TOA measurements are determined based on the at least one non-PRS transmission; obtaining Observed Time Difference of Arrival (OTDOA) measurements by subtracting TOA for the plurality of base stations (201) from a TOA for a reference base station, and transmitting, from the UE (204, 206) to a Location Server (LS) (208), the OTDOA measurements, wherein the LS (208) performs a positioning estimation of the UE (204, 206) based on the OTDOA measurements.