SRS Carrier Switching Without Local Oscillator Retuning
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Solution Overview
Problem
In wireless communications systems, especially with carrier aggregation, terminals face challenges in simultaneously sending sounding reference signals (SRS) on multiple carriers due to hardware and software limitations, leading to interruptions in uplink and downlink data transmission and adverse effects on system performance.
Innovation Solution
A method and apparatus that utilize a digital frequency converter and local oscillator circuit to perform sequential digital and analog frequency conversions, allowing SRS to be transmitted on different carriers in separate time periods using shared local oscillator signals, thereby reducing radio frequency retuning time and improving system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal performs SRS carrier switching to send SRS on all carriers sequentially, then channel quality estimation on all carriers is achieved, but uplink and downlink data transmission are interrupted
Solution Approach 1:
The patent applies preliminary action by performing digital frequency conversion before analog frequency conversion. The digital frequency converter pre-processes the SRS signal by converting it to the target carrier frequency in the digital domain before the analog frequency converter performs the final frequency translation. This preliminary digital processing reduces the complexity and time required for analog retuning, thereby minimizing transmission interruptions while enabling comprehensive channel quality estimation across all carriers.
2Measurement precision
If the terminal sends SRS on all carriers simultaneously, then channel quality estimation is improved, but hardware and software limitations prevent simultaneous transmission
Solution Approach 1:
The patent merges digital frequency conversion and analog frequency conversion into a unified two-stage frequency conversion process. The digital frequency converter and analog frequency converter work together in sequence, with the digital converter handling the initial frequency translation and the analog converter completing the frequency transformation. This merged approach leverages the advantages of both digital and analog processing while working within existing hardware constraints, enabling SRS transmission on multiple carriers without requiring simultaneous transmission capability.
Solution Approach 2:
The digital frequency converter acts as an intermediary between the baseband signal and the analog frequency conversion stage. By performing preliminary frequency translation in the digital domain, it mediates the transition from baseband to radio frequency, reducing the burden on the analog frequency converter and the radio frequency circuitry. This intermediary digital processing step enables the system to handle multiple carrier frequencies within its hardware capabilities.
3Measurement precision
If the terminal performs analog frequency conversion with local oscillator retuning for each carrier, then frequency accuracy is maintained, but radio frequency retuning time increases
Solution Approach 1:
The patent applies preliminary action by performing digital frequency conversion before analog frequency conversion. The digital frequency converter pre-processes the SRS signal by converting it to the target carrier frequency in the digital domain before the analog frequency converter performs the final frequency translation. This preliminary digital processing reduces the complexity and time required for analog retuning, thereby minimizing transmission interruptions while enabling comprehensive channel quality estimation across all carriers.
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 reduces data transmission interruptions and enhances system performance by minimizing radio frequency retuning time during SRS carrier switching, allowing for more efficient channel estimation and data scheduling.
Implementation Method 1
a digital frequency converter, configured to perform a digital frequency conversion operation on the to-be-transmitted signal, to obtain a digital frequency conversion signal
Implementation Method 2
a frequency mixer respectively coupled to the local oscillator circuit and the digital frequency converter, configured to sequentially receive the first digital frequency conversion signal and the second digital frequency conversion signal, and respectively perform analog frequency conversion operations
Implementation Method 3
a local oscillator circuit, configured to output local oscillator signals
Data Source
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AI summary
Embodiments of this application disclose a sounding reference signal SRS sending method and a related apparatus. The method includes: sequentially performing analog frequency conversion operations on a first digital frequency conversion signal and a second digital frequency conversion signal based on local oscillator signals at a same frequency, where the first digital frequency conversion signal corresponds to a first SRS to be transmitted on a first carrier, and the second digital frequency conversion signal corresponds to a second SRS to be transmitted on a second carrier; and transmitting the first SRS on the first carrier in a first time period, and transmitting the second SRS on the second carrier in a second time period, where the second time period is later than the first time period, a sum of a frequency of the first digital frequency conversion signal and a frequency of the local oscillator signal is equal to a frequency of the first carrier, and a sum of a frequency of the second digital frequency conversion signal and the frequency of the local oscillator signal is equal to a frequency of the second carrier. Because the frequency of the local oscillator signal does not need to be adjusted in the foregoing SRS carrier switching process, this solution can reduce a delay of data transmission interruption, to improve system performance.