Receiver Gain Calibration Using TRS for Super-High Order Modulation
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Solution Overview
Problem
Existing wireless communication systems face challenges in supporting super-high order modulations due to limitations in automatic gain control (AGC) and analog-to-digital converter (ADC) dynamic range, especially in fading channels.
Innovation Solution
The system adapts by transmitting a tracking reference signal (TRS) in a first slot adjacent to a second slot allocated for data transmissions with high order modulation. The user equipment (UE) adjusts its receiver gain based on the TRS before receiving the data transmissions, ensuring the gain reflects current channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE uses traditional AGC settings with outdated TRS, then the device complexity is reduced, but the receiver gain accuracy deteriorates leading to poor signal quality for super-high order modulations
Solution Approach 1:
The network entity transmits the tracking reference signal (TRS) in advance in a first slot before the data transmission slot, allowing the UE to perform AGC calibration with updated channel conditions before receiving the actual data transmission. This preliminary action ensures the receiver gain is accurately adjusted based on current channel state rather than outdated settings.
Solution Approach 2:
The tracking reference signal (TRS) acts as an intermediary between the network entity and the data transmission. The TRS carries channel state information that the UE uses to adjust its receiver gain, serving as a mediator that enables accurate AGC calibration without requiring direct feedback or complex adaptive algorithms during the actual data transmission.
2Measurement precision
If the network entity transmits TRS frequently to maintain accurate AGC settings, then the receiver gain accuracy is improved, but the loss of system resources increases
Solution Approach 1:
Instead of transmitting TRS continuously or excessively frequently, the network entity transmits TRS partially - specifically in the first slot before data transmission when super-high order modulation is used. This partial action provides sufficient channel state information for accurate AGC calibration without the overhead of continuous TRS transmission, balancing accuracy with resource efficiency.
3Reliability
If the UE adjusts receiver gain based on outdated AGC settings, then the device complexity is reduced, but the signal quality deteriorates due to fading channel effects
Solution Approach 1:
The system implements feedback through the tracking reference signal (TRS) mechanism. The network entity transmits TRS that contains channel state information, and the UE uses this feedback to adjust its receiver gain accordingly. This feedback loop ensures the receiver gain adapts to current channel conditions including fading effects, improving signal quality for super-high order modulations.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Generally, the described techniques provide for adapting or considering a receiver gain when using super-high order modulations for data transmissions. In one aspect, a network entity may transmit a tracking reference signal (TRS) in a first slot adjacent in time to a second slot allocated for one or more data transmissions associated with a high order modulation. A user equipment (UE) may receive the TRS and may adjust a receiver gain based on the TRS before receiving the one or more data transmissions associated with the high order modulation in the second slot. In another aspect, a UE may indicate (e.g., based on a receiver gain at the UE) a type of slot (e.g., shortened slot) or a maximum number of slots in which a network entity may transmit data transmissions with a high modulation order.