Uplink Transmission Timing Adjustment for Intermodulation Distortion
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Solution Overview
Problem
In 4G/5G dual connectivity scenarios, intermodulation distortion (IMD) caused by concurrent downlink transmissions on different frequencies leads to increased Maximum Sensitivity Degradation (MSD), potentially resulting in dropped UL Scheduling Requests and packet loss, especially in latency-sensitive VoLTE traffic.
Innovation Solution
The terminal prioritizes VoLTE traffic by refraining from sending NR UL traffic when IMD is anticipated, using conflict data to determine overlapping frequency allocations and adjusting transmission times to mitigate IMD effects, thereby ensuring reliable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If concurrent downlink transmissions on different frequencies are performed to increase data throughput, then network capacity and speed are improved, but intermodulation distortion increases causing packet loss and call drops
Solution Approach 1:
The terminal performs preliminary detection of downlink grant records indicating concurrent transmissions on different frequencies. When such grants are detected, the terminal proactively refrains from transmitting uplink data during the overlapping time period, preventing intermodulation distortion from occurring in the first place. This anticipatory action resolves the contradiction by avoiding the harmful interaction before it can degrade reliability.
Solution Approach 2:
The terminal checks for the presence of downlink grant records before initiating uplink transmission. By performing this check in advance and adjusting transmission timing accordingly, the system ensures that uplink transmissions do not occur during periods when intermodulation distortion would be generated, thus maintaining both high throughput and reliable communication.
2Reliability
If uplink transmission timing is adjusted to avoid intermodulation distortion, then call quality and reliability are improved, but transmission latency increases
Solution Approach 1:
The terminal applies timing adjustment selectively only when downlink grant records indicating concurrent transmissions are detected. In normal conditions without intermodulation risk, uplink transmissions proceed at optimal times without delay. This partial application of the timing adjustment principle ensures call quality is maintained when needed, while minimizing unnecessary latency in normal operating conditions.
Data Source
AI summary
A telecommunication terminal can include a memory storing conflict data. The terminal can receive an uplink (UL) grant record associated with a time of permitted UL transmission, and two downlink (DL) grant records, each indicating a respective frequency and associated with a respective time. The terminal can determine that the times of DL transmission at least partly overlap with the time of UL transmission. The terminal can determine, based on the conflict data, that the frequencies of DL transmission are associated with an inter-band conflict. In response, the terminal can transmit UL data at a time later than the time of permitted UL transmission. In some examples, the terminal can receive two DL grant records, make a determination that a frequency combination of two granted DL frequencies is within a predetermine frequency range, and, in response, transmit the UL data at a time different from a DL transmission time.