Uplink Reference Signal Delay Compensation for 5G Geolocation
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Solution Overview
Problem
Current geolocation techniques are inaccurate due to the increasing separation of Distributed Unit (DU) and Radio Unit (RU) equipment, which introduces non-negligible trip times that corrupt geolocation measurements, especially in 5G networks where these components are often separated by distances varying from a few meters to several tens of kilometers.
Innovation Solution
A method that compensates for these inaccuracies by recording a fictitious time of arrival for uplink reference signals, adding a delay greater than the actual trip time between the radio unit and the network entity, allowing the network entity to calculate the time of flight accurately by subtracting this delay from the total trip time, thereby correcting geolocation measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DU and RU equipment are separated by large distances, then network flexibility and scalability are improved, but geolocation measurement precision deteriorates due to non-negligible trip times
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the trip time between DU and RU in a lookup table before geolocation measurements are performed. This pre-computed trip time is then used to compensate for the separation distance effect during geolocation processing, allowing the system to maintain measurement precision while benefiting from the flexibility of distant DU-RU separation.
2Adaptability or versatility
If DU and RU equipment are separated by large distances, then network scalability is improved, but measurement accuracy deteriorates due to increased trip time
Solution Approach 1:
The patent introduces an intermediary approach by using a lookup table as a mediator between the DU-RU separation and the geolocation measurements. The lookup table stores pre-computed trip times for various separation distances and acts as an intermediary that translates the physical separation into compensation values, enabling accurate geolocation despite large DU-RU distances.
3Reliability
If actual trip time between radio unit and network entity is used, then transmission conditions are accounted for, but geolocation precision is corrupted by variable delays
Solution Approach 1:
The patent applies parameter changes by transforming the variable actual trip time into a fixed compensation value. Instead of using the actual varying trip time directly in geolocation calculations (which would corrupt precision), the system changes the parameter to a predetermined compensation value derived from the lookup table, thereby maintaining both transmission reliability and geolocation precision.
Data Source
AI summary
A method for receiving an uplink reference signal sent by a mobile terminal to a network entity through a radio unit connected to an antenna, and used to geolocate the mobile terminal. The method is implemented by the network entity and includes: recording, by way of time of arrival of the reference signal, a time obtained by adding a delay, called a waiting delay, to the time at which the reference signal was sent by the radio unit, the waiting delay being larger in value than a transmit path time of a comparison signal, between the radio unit and the network entity; and sending a message to a geolocation server, including information relating to the recorded time of arrival.