Autocorrelation-Based OFDM Signal Identification

Solution Overview

Problem

Mobile communication terminals face challenges in rapidly identifying communication protocols, particularly when supporting multiple Radio Access Technologies (RATs) like LTE and WCDMA, due to similar signal spectra, leading to lengthy and power-consuming Public Land Mobile Network (PLMN) search processes.

Innovation Solution

The method involves computing multiple autocorrelations of received signals with a fixed time offset corresponding to the symbol interval of the communication protocol, accumulating these autocorrelations to detect predefined peaks, and using cumulative autocorrelation analysis to identify whether the signal conforms to specific protocols like LTE or WCDMA, enabling fast and reliable protocol identification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional spectral measurement methods are used to identify communication protocols, then protocol identification can be performed, but the PLMN search process becomes lengthy and power-consuming

Engineering Contradiction:

Improveprotocol identification accuracyVSAvoidPLMN search duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts the cyclic prefix characteristic from the signal structure as a distinctive feature for protocol identification. By focusing on this specific extracted feature rather than performing complete spectral analysis, the system achieves fast and reliable protocol detection, resolving the contradiction between identification reliability and search duration

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary autocorrelation analysis to detect the presence of cyclic prefixes before committing to a full protocol identification process. This preliminary action allows the system to quickly eliminate non-matching protocols and proceed only with promising candidates, significantly reducing the overall PLMN search time while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional spectral measurement methods are used to identify communication protocols, then protocol identification can be performed, but power consumption increases

Engineering Contradiction:

Improveprotocol identification accuracyVSAvoidterminal power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the cyclic prefix characteristic from the signal structure as a distinctive feature for protocol identification. By focusing on this specific extracted feature rather than performing complete spectral analysis, the system achieves fast and reliable protocol detection, resolving the contradiction between identification reliability and search duration

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary autocorrelation analysis to detect the presence of cyclic prefixes before committing to a full protocol identification process. This preliminary action allows the system to quickly eliminate non-matching protocols and proceed only with promising candidates, significantly reducing the overall PLMN search time while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If the terminal scans multiple frequency bands and RATs to support multiple protocols, then adaptability improves, but the identification process becomes more complex and time-consuming

Engineering Contradiction:

Improvemulti-RAT support capabilityVSAvoidprotocol identification process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the protocol identification process into distinct stages: first detecting cyclic prefix characteristics via autocorrelation, then proceeding to protocol-specific analysis only for signals that exhibit CP features. This segmentation allows the terminal to efficiently handle multiple RATs by applying complex identification algorithms only where necessary, reducing overall process complexity while maintaining multi-protocol adaptability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary autocorrelation analysis to detect the presence of cyclic prefixes before committing to a full protocol identification process. This preliminary action allows the system to quickly eliminate non-matching protocols and proceed only with promising candidates, significantly reducing the overall PLMN search time while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8938016B1Fast identification of OFDM signal

Publication Date: 2015.01.20 MARVELL ASIA PTE LTD

AI summary

A method includes receiving a signal in a frequency band, which is assignable at least to a communication protocol in which Cyclic Prefixes (CP) are added to symbols having a predefined symbol interval. Multiple autocorrelations of the received signal are computed with a fixed time offset that depends on the symbol interval defined in the communication protocol, and the multiple autocorrelations are accumulated to produce a cumulative autocorrelation. An identification is made, based on the cumulative autocorrelation, whether the received signal is formatted in accordance with the communication protocol.