Adaptive Signal Linearization for Modulation-Dependent EVM Control
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Solution Overview
Problem
Current signal linearization techniques in LTE-LAA wireless networks consume significant computational resources and power, and are not beneficial for all modulation orders, leading to increased complexity and costs, while relaxing ACLR requirements can impact EVM compliance, limiting data rates and system capacity.
Innovation Solution
Implementing adaptive signal linearization by selectively applying digital pre-distortion techniques based on modulation order thresholds, allowing signal linearization only when beneficial, thereby reducing processing and power consumption and maintaining EVM compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal linearization technique is applied to all signals, then EVM compliance is improved, but processing complexity and power consumption increase
Solution Approach 1:
The patent changes the parameter of signal linearization application from a constant (always applied) to a variable condition (applied only when modulation order exceeds threshold). This allows the system to adapt processing complexity to the actual signal requirements, reducing unnecessary processing for low-order modulations while maintaining EVM compliance for high-order modulations that require it.
Solution Approach 2:
The patent introduces dynamic control of signal linearization based on real-time modulation order detection. The system dynamically switches between linearization and non-linearization states depending on the modulation scheme being used, making the processing complexity adaptable to current transmission requirements rather than statically high for all signals.
2Reliability
If signal linearization technique is applied to all signals, then EVM compliance is improved, but power consumption increases
Solution Approach 1:
The patent changes the energy consumption parameter by making signal linearization conditional on modulation order. Low-order modulations (QPSK, 16QAM) that don't require linearization consume less processing power, while high-order modulations (64QAM, 256QAM) that benefit from linearization still receive the processing when needed, optimizing the overall energy efficiency of the base station.
Solution Approach 2:
The patent applies signal linearization partially - only to the extent necessary for high-order modulations that require it, rather than applying it excessively to all modulation types. This partial application reduces unnecessary power consumption while maintaining sufficient EVM compliance for signals that actually need the processing.
3Device complexity
If signal linearization technique is not applied, then processing complexity is reduced, but data rates are limited due to EVM compliance issues
Solution Approach 1:
The patent enables the system to achieve high data rates by conditionally applying linearization only when high-order modulations are used. This selective approach allows the system to unlock the high throughput potential of 64QAM and 256QAM when channel conditions permit, while avoiding the processing overhead when lower data rates are sufficient.
4Productivity
If ACLR requirements are relaxed, then system capacity increases, but EVM compliance is impacted
Solution Approach 1:
The patent applies different quality requirements to different signal types - high EVM compliance (via linearization) for high-order modulations that are sensitive to distortion, and relaxed requirements for low-order modulations that are more robust. This local quality differentiation allows the system to optimize overall capacity while maintaining compliance where it matters most.
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 enhances system capacity by reducing overall processing and power consumption at base stations, allowing more devices to be served simultaneously while meeting 3GPP EVM requirements, and optimizing data rates by applying signal linearization only to high-order modulation signals.
Implementation Method 1
selectively performing a signal linearization technique on the signal, wherein the signal linearization technique comprises digital pre-distortion
Data Source
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AI summary
According to some embodiments, a method of transmitting a radio signal in a first wireless network element comprises receiving, at an input of a radio transmitter, a signal for wireless transmission; selectively performing a signal linearization technique on the signal; amplifying the signal with a non-linear amplifier; and transmitting the amplified signal to a 5 second wireless network element. According to particular embodiments, selectively performing the signal linearization technique comprises determining a modulation order of the received signal and determining the modulation order exceeds a modulation order threshold.