MIMO Timing Error Estimation Using PN Sequence Correlation

Solution Overview

Problem

Conventional methods for estimating timing errors and frequency offsets in OFDM MIMO systems fail to accurately account for ISI effects, leading to interference and degraded decoding performance.

Innovation Solution

A method and device that utilize a PN sequence to estimate timing errors and frequency offsets by processing signals through multiple antennas, extracting preamble symbols, and compensating errors using local PN sequences, effectively addressing the ISI and ICI issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional DA or NDA algorithms are used for timing and frequency offset estimation, then the system can achieve basic synchronization, but the estimation accuracy deteriorates due to unaccounted ISI effects in multipath channels

Engineering Contradiction:

Improvetiming error estimation accuracyVSAvoiddecoding performance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing timing offset estimation and compensation before frequency offset estimation. The receiver first estimates the timing offset using the preamble symbol, compensates for it, and then proceeds to frequency offset estimation. This sequential approach ensures that each estimation step operates on optimally pre-processed signals, improving overall accuracy despite ISI effects in multipath channels.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using the estimated timing offset to adjust the sampling position of the received signal before subsequent processing. The receiver continuously monitors the correlation between the received preamble and local preamble, uses this feedback to refine timing offset estimates, and adjusts the sampling clock accordingly to maintain accurate synchronization despite multipath interference.

Inventive Principle:

Principle #23Feedback

2Speed

If frequency offset compensation is performed without accurate timing synchronization, then the system can proceed with frequency correction, but the orthogonality between subcarriers deteriorates causing ICI interference

Engineering Contradiction:

Improvesynchronization processing speedVSAvoidICI interference

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing timing offset estimation and compensation before frequency offset estimation. The receiver first estimates the timing offset using the preamble symbol, compensates for it, and then proceeds to frequency offset estimation. This sequential approach ensures that each estimation step operates on optimally pre-processed signals, improving overall accuracy despite ISI effects in multipath channels.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the receiver uses complex multipath channel equalization before synchronization, then the system can handle severe fading conditions, but the device complexity and computational load increase significantly

Engineering Contradiction:

Improvesignal detection reliabilityVSAvoidsynchronization device complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing timing offset estimation and compensation before frequency offset estimation. The receiver first estimates the timing offset using the preamble symbol, compensates for it, and then proceeds to frequency offset estimation. This sequential approach ensures that each estimation step operates on optimally pre-processed signals, improving overall accuracy despite ISI effects in multipath channels.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements self-service by using the transmitted preamble symbol itself as the reference for both timing and frequency offset estimation. The receiver correlates the received preamble with a local copy of the known preamble sequence, automatically extracting timing and frequency offset information without requiring external reference signals or complex pilot insertion schemes, thereby reducing system complexity.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7778338B2Method and apparatus for estimating timing error and frequency offset of MIMO system

Publication Date: 2010.08.17 SAMSUNG ELECTRONICS CO LTD

AI summary

The present invention relates to a method and device for estimating a timing error and a frequency offset in the MIMO mobile communication system. In a system including a plurality of transmit antennas and a plurality of receive antennas, a predetermined preamble symbol is inserted into a frame to be transmitted by a transmitting device, and pseudo noise is multiplied to the preamble symbol, and result signal is transmitted through each transmit antenna. A receiving device receives the signal through each receive antenna, extracts a preamble symbol from the OFDM symbol, and multiplies local pseudo noise that corresponds to the pseudo noise used by the transmitting device and is shifted by the extracted preamble symbol. A timing error is estimated and compensated according to the correlation of the pseudo noise of the transmitting device and the local pseudo noise of the receiving device. A frequency offset is estimated and compensated according to the phase difference between the preamble symbols. Therefore, the system is realized in a simpler manner and timing error and frequency offset estimation and compensation performance is further improved.