Fast Resynchronization in DVB-H Receivers

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Solution Overview

Problem

In DVB-H systems, conventional frame resynchronization techniques consume significant battery power and time, as they require extensive steps such as initial window placement, frequency offset estimation, and correlation with synchronization words, which are inefficient for handheld devices with limited power and time slices.

Innovation Solution

The method involves bypassing conventional correlation steps by using information from previous time slices to adjust OFDM symbol window locations and determining symbol numbers based on scattered pilot positions, reducing the need for frame synchronization and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional frame resynchronization techniques are used (correlating TPS synchronization words, performing initial window placement, frequency offset estimation), then synchronization accuracy is maintained, but resynchronization time increases and battery power consumption increases

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidresynchronization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The receiver performs preliminary actions during the previous time slice by storing the last known good OFDM symbol window location and scattering pilot positions. This preliminary preparation allows the receiver to skip time-consuming correlation steps in the current time slice, achieving fast resynchronization by simply adjusting the stored window location based on known time drift characteristics.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention skips the conventional time-consuming correlation steps (TPS synchronization word correlation, initial window placement) by directly computing the OFDM symbol window location adjustment based on stored information from the previous time slice. This rushing through of intermediate steps achieves fast resynchronization while maintaining accuracy through the use of stored scattering pilot positions for validation.

Inventive Principle:

Principle #21Skipping (Rushing through)

2Reliability

If conventional frame resynchronization techniques are used (extensive correlation steps, frequency offset estimation), then synchronization is achieved, but battery power consumption increases

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The receiver performs preliminary actions during the previous time slice by storing the last known good OFDM symbol window location and scattering pilot positions. This preliminary preparation allows the receiver to skip power-intensive correlation operations in the current time slice, achieving low-power resynchronization by only performing minimal adjustments to the stored window location.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention skips the conventional power-consuming correlation steps (TPS synchronization word correlation, initial window placement, frequency offset estimation) by directly computing the OFDM symbol window location adjustment based on stored information from the previous time slice. This rushing through of intermediate steps achieves power-efficient resynchronization while maintaining reliability through validation using stored scattering pilot positions.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Loss of time

If fast resynchronization by skipping correlation steps is implemented, then resynchronization time and power consumption are reduced, but the ability to handle high frequency drift and echo conditions may be compromised

Engineering Contradiction:

Improveresynchronization timeVSAvoidrobustness to frequency drift and echo

Core Design Contradiction:

Loss of timeVSAdaptability or versatility

Solution Approach 1:

The receiver uses feedback from the previous time slice by storing the last known good OFDM symbol window location and scattering pilot positions. This feedback mechanism allows the receiver to adapt to frequency drift and echo conditions by comparing the stored scattering pilot positions with received signals, enabling the system to maintain robustness while achieving fast resynchronization through minimal adjustments to the stored window location.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system serves itself by using its own previously stored information (OFDM symbol window location and scattering pilot positions) to perform fast resynchronization. The receiver automatically adjusts the stored window location based on known time drift characteristics and validates using stored scattering pilot positions, eliminating the need for external synchronization signals and maintaining robustness without requiring extensive correlation steps.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9055324B2Fast resynchronization for reception in time slicing

Publication Date: 2015.06.09 MAXLINEAR INC

AI summary

A method and an apparatus for achieving fast resynchronization of received signals in a time slice in DVB-T/H systems. When the clock drift is low, the location of the symbol window can be decided based on a previous time slice. When the clock drift is high and when there are large delay spreads, the location of the symbol window can be decided based on the detected scattered pilot positions. The placement of the symbol window can further be enhanced through processing of the received TPS bits.