Time Domain Cell Search Using Pre-Rotated Binary Quantized Preambles

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Solution Overview

Problem

Conventional cell searching apparatuses in OFDMA mobile communication systems face challenges in accurately identifying cell boundaries and segment numbers due to frame boundary timing errors and subcarrier frequency offsets, leading to increased computational load and implementation complexities.

Innovation Solution

A cell searching apparatus and method that perform correlation in the time domain using pre-rotated, binary quantized preamble sequences, reducing errors and complexity by identifying preamble indices and timing indices through iterative correlation within a correlation window, and including an initial frame boundary detector and frequency offset estimator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional frequency domain correlation is used for cell searching, then cell identification can be performed, but frame boundary timing errors and subcarrier frequency offsets cause increased computational load and implementation complexities

Engineering Contradiction:

Improvecell identification accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the frequency domain correlation mechanism with a time domain correlation mechanism. By substituting the mathematical domain from frequency to time, the system eliminates the computational complexities and errors associated with frequency domain processing while maintaining cell identification capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of correlation processing from frequency domain to time domain. This parameter transformation fundamentally alters how correlation is performed, reducing computational load and eliminating errors related to frame boundary timing and frequency offsets that plague the frequency domain approach

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If frequency domain correlation is performed for cell searching, then cell identification is achieved, but hardware and software complexity increases

Engineering Contradiction:

Improvepreamble index identification accuracyVSAvoidhardware and software complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent substitutes the frequency domain correlation system with a time domain correlation system. This substitution simplifies both hardware and software implementations by eliminating the need for complex frequency domain processing while maintaining accurate preamble index identification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of performing correlation in the conventional frequency domain, the patent inverts the approach by performing correlation in the time domain. This inversion fundamentally simplifies the implementation while achieving the same identification goal with reduced complexity

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If conventional cell searching method is used, then cell search function is provided, but power consumption increases

Engineering Contradiction:

Improvecell searching speedVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the energy-intensive frequency domain correlation with a more efficient time domain correlation. This substitution reduces the computational operations required, thereby decreasing power consumption while maintaining or improving cell searching speed

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

By changing the correlation domain from frequency to time, the patent fundamentally alters the computational efficiency. This parameter change reduces the number of operations required for cell searching, directly lowering power consumption while maintaining search functionality

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7616679B2Method and apparatus for searching cells utilizing down link preamble signal

Publication Date: 2009.11.10 POS DATA CO LTD

AI summary

An apparatus for searching for a cell in a mobile communication system, including: a preamble sequence storage unit storing preamble sequences each of which corresponds to one preamble index, and a cell searching unit correlating a received signal and the stored preamble sequences in a time domain and identifying the preamble index corresponding to the received signal. The cell searching apparatus correlates a received signal and stored preamble sequences in a time domain. The apparatus employs binary quantization of preamble sequences to reduce calculation and memory size. Also, the stored preamble sequences are phase pre-rotated according to a segment number, to prevent from a burden of frequency offset correction caused by three different hypotheses. Accordingly, a complexity of the cell searching apparatus is reduced and cell searching performance becomes more accurate.