Adaptive Radio Signal Linearization for EVM and Power Trade-Offs
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Solution Overview
Problem
Current signal linearization techniques, such as digital pre-distortion, consume computational resources and power, and are not beneficial for all radio transmissions, particularly those using low order modulation, leading to increased complexity and costs in LTE-LAA base stations, which may not meet the 3GPP error vector magnitude requirements when ACLR is relaxed.
Innovation Solution
Implementing adaptive signal linearization by selectively applying digital pre-distortion based on modulation order thresholds, allowing the technique to be applied only when necessary, thereby reducing processing and power consumption and maintaining compliance with 3GPP standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal linearization technique is applied to all radio transmissions, then EVM requirements are met, but computational resources and power consumption increase
Solution Approach 1:
The patent changes the parameter of signal linearization application from a constant state (always applied) to a variable state (conditionally applied based on modulation order). By monitoring the modulation order parameter and selectively enabling/disabling signal linearization based on threshold comparisons, the system adapts power consumption to actual transmission requirements, reducing energy waste on transmissions that don't need linearization while maintaining EVM compliance when necessary.
Solution Approach 2:
Instead of applying signal linearization to all transmissions (excessive action), the patent applies it only to partial cases where the modulation order exceeds the threshold. This partial application eliminates unnecessary computational overhead and power consumption for low-order modulations that don't require linearization, while still ensuring EVM requirements are met for high-order modulations that benefit from or require the technique.
2Reliability
If signal linearization technique is applied to all radio transmissions, then EVM requirements are met, but device complexity increases
Solution Approach 1:
The patent introduces dynamic control to the signal linearization process by continuously monitoring the modulation order and adaptively adjusting whether linearization is applied. This dynamic approach allows the base station to switch between linearization and non-linearization modes based on real-time transmission characteristics, reducing overall system complexity compared to always maintaining full linearization capability active, while still ensuring EVM compliance when needed.
Solution Approach 2:
The system changes the operational parameter of the signal linearization module from a fixed enabled state to a dynamically controlled state based on modulation order thresholds. This parameter change reduces device complexity by allowing the linearization functionality to be selectively activated only when required, rather than maintaining constant readiness for all transmission types.
3Use of energy by moving object
If signal linearization technique is applied selectively based on modulation order, then power consumption is reduced, but EVM requirement compliance may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the modulation order is continuously monitored and fed back to the signal linearization control logic. Based on this feedback, the system determines whether to apply linearization by comparing the modulation order against a threshold. This closed-loop feedback ensures that linearization is applied precisely when needed to meet EVM requirements while avoiding unnecessary application that would waste power, thus resolving the trade-off between power consumption and compliance.
Solution Approach 2:
The system uses parameter changes in the modulation order as the basis for controlling linearization application. When the modulation order parameter exceeds the threshold, linearization is activated to ensure EVM compliance; when it remains below the threshold, linearization is deactivated to save power. This parameter-driven control strategy maintains reliability while optimizing power consumption.
Data Source
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 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.