Radio Unit Delay Compensation for Geolocation Precision
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Solution Overview
Problem
Current geolocation techniques using time differences of arrival or reference signal time differences are imprecise due to the increasing separation of distributed units (DUs) and radio units (RUs) in the radio access network, leading to non-negligible transit times that invalidate geolocation measurements.
Innovation Solution
A method involving a radio unit connected to an antenna, which receives a reference signal and applies a delay period greater than the transit time of a comparison signal to transmit it to a mobile terminal, allowing for the calculation of the time of flight by subtracting the constant upstream transit time from the total transit time, thereby compensating for transmission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If reference signals are transmitted directly from network entity to mobile terminal via radio unit, then the transmission path is simple, but the geolocation measurement precision deteriorates due to non-negligible transit time between DU and RU
Solution Approach 1:
The radio unit performs preliminary action by measuring the transit time of the reference signal between the network entity and the radio unit itself, before using this information for geolocation measurements. This preliminary measurement allows the system to compensate for the DU-RU transmission delay in subsequent geolocation calculations, resolving the contradiction between simple transmission path and precise measurement.
2Productivity
If the transit time between DU and RU is ignored, then the calculation is simple, but the geolocation accuracy deteriorates due to increasing separation distance
Solution Approach 1:
The system implements feedback by having the radio unit measure and report the actual transit time of reference signals between the network entity and the radio unit. This feedback information is then used to adjust and compensate for transmission delays in the geolocation calculations, allowing the system to maintain both computational efficiency and measurement precision despite increasing separation distances.
3Ease of operation
If reference signals are transmitted without delay compensation, then the transmission is straightforward, but the time of flight calculation becomes inaccurate
Solution Approach 1:
The invention extracts and separates the transmission delay component (time between DU and RU) from the total transmission time. By measuring the reference signal transit time specifically between the network entity and radio unit, the system can extract this delay component and subtract it from the total time to obtain the accurate time of flight through the air, thus maintaining ease of operation while improving measurement precision.
Data Source
AI summary
A method for transmitting a downlink reference signal from a network entity to a mobile terminal via a radio unit connected to an antenna, used to geolocate the mobile terminal. The method is implemented by the radio unit and includes: receiving the reference signal from the network entity and destined for the mobile terminal; and transmitting the reference signal to the mobile terminal upon expiry of a delay period with respect to the transmission time of the reference signal by the network entity. The delay period has a value greater than a transmission travel time of a comparison signal between the network entity and the radio unit.