Uplink Carrier Aggregation Filtering for Harmonic Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE and LTE-Advanced systems, the aggregation of multiple downlink and uplink carriers leads to harmonic interference and intermodulation distortion, particularly when transmitting uplink signals, which degrades the sensitivity of the terminal's uplink band, especially when using E-UTRA operating bands 20 and 47.
Innovation Solution
The implementation of a harmonic trap filter in the terminal to mitigate harmonic interference, which sets the maximum sensitivity degradation (MSD) to 0.16 dB, compared to 5.08 dB without the filter, by controlling the transceiver to manage the uplink and downlink signal aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two uplink carriers are aggregated for transmission, then the uplink transmission capacity is improved, but harmonic interference and intermodulation distortion are generated which degrade the terminal's uplink band sensitivity
Solution Approach 1:
The patent introduces a harmonic trap filter as an intermediary component between the uplink transmitter and the terminal's receiving path. This filter specifically targets and removes harmonic frequencies generated by the two uplink carriers before they can interfere with the downlink reception, thereby resolving the contradiction between maintaining high uplink transmission capacity and eliminating harmful harmonic interference.
2Reliability
If a harmonic trap filter is added to mitigate harmonic interference, then the sensitivity degradation is reduced to 0.16 dB, but the device complexity increases
Solution Approach 1:
The patent applies the harmonic trap filter selectively only in the specific frequency bands where harmonic interference problems occur ( Bands 20 and 47), rather than implementing a comprehensive filtering solution across all bands. This localized approach maintains terminal sensitivity while minimizing the increase in device complexity by targeting only the problematic areas.
3Adaptability or versatility
If carrier aggregation is implemented with bands 20 and 47, then the network coverage and bandwidth utilization are improved, but the intermodulation distortion affects the downlink reception quality
Solution Approach 1:
The patent converts the harmful intermodulation distortion products into a manageable filtering problem by using the harmonic trap filter to selectively remove only the problematic frequency components while preserving the desired downlink signal. This approach allows the system to maintain the benefits of carrier aggregation with bands 20 and 47 while eliminating the detrimental effects on downlink reception quality.
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
The harmonic trap filter effectively reduces the MSD to 0.16 dB, significantly improving the terminal's sensitivity and reducing interference, thereby enhancing the performance of carrier aggregation in LTE and LTE-Advanced systems.
Implementation Method 1
a harmonic trap filter for mitigating harmonic interference
Data Source
AI summary
When a terminal aggregates three downlink carriers by using the carrier aggregation (CA) of the LTE-A technology and transmits an uplink signal on two uplink carriers while aggregating at least two uplink carriers, a harmonic component and an intermodulation distortion (IMD) component are generated, thereby influencing a downlink band of the terminal itself. Therefore, the present specification presents a scheme therefor.