UL Reference Signal Pre-Compensation for Doppler Offset Alignment
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Solution Overview
Problem
In wireless communications systems, particularly in single-frequency network scenarios with high-speed user equipment, the Doppler effect causes significant frequency offsets that complicate data transmission, leading to communication challenges.
Innovation Solution
The use of uplink reference signals (UL-RS) for frequency offset pre-compensation, where user equipment determines frequency offsets based on downlink reference signals (DL-RS) from multiple base stations, applying weighting factors to select an appropriate UL-RS frequency, which base stations then use to adjust their downlink data transmissions, mitigating frequency offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If downlink reference signals are transmitted from multiple base stations using the same frequency in single-frequency network scenarios, then network coverage and signal strength are improved, but frequency offsets caused by Doppler effect increase due to high-speed user equipment movement
Solution Approach 1:
The patent applies preliminary action by having the user equipment transmit an uplink reference signal before the actual downlink data transmission. This uplink reference signal is used to measure the actual frequency offset in advance, allowing the base station to pre-compensate for the Doppler effect in subsequent downlink transmissions. The frequency offset measurement and compensation are performed beforehand to ensure accurate data reception.
Solution Approach 2:
The patent implements feedback by using the uplink reference signal transmission from the user equipment to obtain frequency offset information. The base station receives this feedback about the actual frequency conditions and uses it to adjust the downlink transmission frequency. This closed-loop feedback mechanism enables dynamic adaptation to changing Doppler conditions in single-frequency network scenarios.
2Reliability
If frequency offset pre-compensation is performed using uplink reference signals, then communication reliability is improved, but system complexity increases due to additional frequency determination and adjustment processes
Solution Approach 1:
The patent applies self-service by having the user equipment autonomously determine and transmit the uplink reference signal at an appropriate frequency without requiring complex network coordination. The user equipment independently measures downlink frequency offsets and selects a suitable uplink frequency, then transmits the reference signal for the base station to use in compensation. This self-service approach simplifies the overall system complexity while maintaining reliability.
Solution Approach 2:
The patent uses parameter changes by adjusting the frequency parameter of the uplink reference signal transmission based on measured Doppler conditions. Instead of using a fixed frequency, the system dynamically changes the uplink frequency parameter to account for high-speed movement effects. This parameter adaptation enables effective frequency offset pre-compensation without requiring complex processing algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables effective communication by aligning downlink data transmissions with the user equipment's center frequency, improving communication quality and reliability in high-speed scenarios.
Implementation Method 1
the Doppler effect causes significant frequency offsets that complicate data transmission
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may determine, based at least in part on a first downlink reference signal transmitted from a first base station using a downlink reference signal frequency, a first frequency offset associated with transmissions between the UE and the first base station. The UE may determine, based at least in part on a second downlink reference signal transmitted from a second base station using the downlink reference signal frequency, a second frequency offset associated with transmissions between the UE and the second base station. The UE may transmit, to the first base station and the second base station, at least one uplink reference signal using an uplink reference signal frequency that is based at least in part on the first frequency offset and the second frequency offset.