Scrambling Sequence Control for Digital Post Distortion
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Solution Overview
Problem
In wireless communications, the non-linearity of power amplifiers (PAs) causes mismatch between data and pilot resource elements, leading to errors due to incorrect PA modeling, as data resource elements experience higher nonlinearities than corresponding pilot resource elements.
Innovation Solution
A transmitting device selects a scrambling sequence per symbol period to reduce variance in the non-linearity parameter for PA output between data and pilot resource elements, based on a PA model, and optionally indicates this sequence to the receiving device, allowing it to blindly estimate or use the sequence for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single scrambling sequence is used for all resource elements, then the system complexity is reduced, but the PAPR variance between data and pilot resource elements increases due to different non-linearity experiences
Solution Approach 1:
The patent applies dynamics by making the scrambling sequence selection variable and adaptive rather than fixed. The transmitting device dynamically selects different scrambling sequences from a set of candidate sequences based on the actual PAPR characteristics and non-linearity conditions of each symbol period, allowing the system to adapt to changing transmission conditions and minimize PAPR variance between data and pilot resource elements
Solution Approach 2:
The patent changes the parameter of scrambling sequence selection by introducing multiple candidate scrambling sequences and selecting among them based on PAPR criteria. This parameter change enables the system to optimize the match between data and pilot resource elements under different non-linearity conditions, improving PA modeling accuracy without significantly increasing system complexity
2Reliability
If the transmitting device indicates the selected scrambling sequence to the receiving device, then the receiving device can accurately decode the data, but the control signaling overhead increases
Solution Approach 1:
The patent applies self-service by enabling the receiving device to autonomously determine the scrambling sequence used by the transmitting device. The receiving device can either blindly estimate the scrambling sequence from the received signal or determine it based on predefined rules and known parameters, eliminating the need for explicit indication signaling and thereby reducing control signaling overhead while maintaining decoding accuracy
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting device may select a scrambling sequence to use per symbol to reduce variance in a non-linearity parameter for a power amplifier (PA) output between a data symbol and a pilot symbol based on a PA model for at least one pilot symbol or one or more parameters of the model. The receiving device may indicate a capability to blindly estimate the scrambling sequence the transmitting device selected to the transmitting device. If the transmitting device does not receive the capability message from the receiving device or if the capability message indicates the receiving device is not capable of blind estimation, the transmitting device may indicate the selected scrambling sequence to the receiving device. Otherwise, the transmitting device may not indicate the selected scrambling sequence to the receiving device, and the receiving device may blindly estimate the scrambling sequence.