OFDM Receiver Powerdown via Subcarrier Interference Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing wireless communication systems face inefficiencies in power management due to unreliable Clear Channel Assessment mechanisms, leading to unnecessary power consumption when interferers are present on shared communication channels, especially in scenarios with overlapping frequency bands and varying data rates.

Innovation Solution

A method and apparatus for detecting interferers by measuring and comparing signal strengths across subcarriers, using thresholds dependent on data rates and channel coding methods to power down receivers when interference exceeds predetermined levels, employing techniques such as error vector magnitude calculations and cyclic prefix cross-correlation to identify and respond to interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the receiver operates continuously to ensure successful packet reception, then reception reliability is improved, but power consumption increases

Engineering Contradiction:

Improvepacket reception reliabilityVSAvoidreceiver power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary interference detection by analyzing subcarrier signal strengths and comparing them against threshold criteria before the receiver fully operates. This preliminary action identifies interference conditions early, allowing the receiver to be powered down preemptively when interference is detected, thus avoiding unnecessary power consumption while maintaining reliable reception when conditions are favorable

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors subcarrier signal strengths and provides feedback to the power control mechanism. When the feedback indicates that interference exceeds threshold levels (comparing occupied vs. unoccupied subcarrier strengths), the receiver is powered down. This closed-loop feedback system dynamically adjusts receiver operation based on real-time channel conditions, balancing reliability and power consumption

Inventive Principle:

Principle #23Feedback

2Difficulty of detecting and measuring

If the Clear Channel Assessment mechanism is used to detect interference, then channel awareness is improved, but reliability deteriorates when only some subcarriers are interfered with

Engineering Contradiction:

Improveinterference detection capabilityVSAvoidbackoff mechanism reliability

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

Instead of treating the channel as a single entity, the system segments the channel into individual subcarriers and evaluates the signal strength of each subcarrier separately. By comparing occupied subcarrier strengths against unoccupied subcarrier strengths on a per-subcarrier basis, the system can detect partial interference conditions that traditional CCA mechanisms miss, thereby improving the reliability of interference detection and subsequent backoff decisions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system applies different evaluation criteria to different parts of the channel spectrum. Rather than using a single threshold for the entire channel, it compares local subcarrier signal strengths against local noise floors (unoccupied subcarriers) and applies data-rate-dependent thresholds. This localized quality assessment enables reliable detection of interference in specific frequency regions without false positives from other channel regions

Inventive Principle:

Principle #3Local quality

3Productivity

If multiple access points and stations operate in the same channel to increase bandwidth utilization, then network throughput is improved, but interference opportunities increase

Engineering Contradiction:

Improvenetwork bandwidth utilizationVSAvoidchannel interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adapts its interference detection thresholds based on the data rate being used. Higher data rates employ more stringent thresholds since they are more susceptible to interference, while lower data rates use more lenient thresholds. This dynamic threshold adjustment allows the system to operate reliably in high-interference environments when using robust modulations while maintaining high throughput when conditions permit, thus enabling efficient coexistence of multiple access points and stations

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10893477B2Same-channel interference detection and early receiver powerdown for OFDM signal processor

Publication Date: 2021.01.12 SILICON LABORATORIES INC

AI summary

A power saving receiver has a controller which is operative to remove power from the receiver when a threshold is exceeded during reception of a packet. The threshold level is formed by comparison of any of: signal energy of unoccupied subcarriers less the signal energy in occupied subcarriers; signal energy in a first range of occupied subcarriers compared to signal energy in a different range of occupied subcarriers; error vector magnitude from a first set of subcarriers to a second set of subcarriers in a different spectral region of the channel; cyclic prefix cross-correlation, or common phase error increase.