Base Station Reference Timing Adjustment for Interference Mitigation

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Solution Overview

Problem

In next-generation PHS, base stations face challenges in maintaining accurate data reception from communication terminals due to synchronization issues and inter-carrier interference, leading to degraded communication quality when signals from multiple terminals are not received at coincident timings.

Innovation Solution

A base station system that adjusts its reference timing based on interference wave levels in unit radio resources, using an FFT processing unit and interference wave level acquisition unit to determine optimal timing, ensuring orthogonality and accurate data retrieval while minimizing inter-carrier interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the base station receives signals from multiple communication terminals without adjusting reference timing, then the base station can perform communication with multiple terminals, but the orthogonality among signals is lost and inter-carrier interference occurs

Engineering Contradiction:

Improvedata reception accuracyVSAvoidinter-carrier interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The base station performs a ranging process before normal communication to obtain delay amounts from communication terminals. Based on these delay amounts, the base station adjusts transmission timing control signals to pre-align the reception timing of signals from multiple terminals, ensuring they arrive at the reference timing and maintain orthogonality, thereby preventing inter-carrier interference before it occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The base station changes the timing parameter of transmission control signals sent to communication terminals. By adjusting the transmission timing based on measured delay amounts, the base station ensures that signals from multiple terminals are received at coincident timings, maintaining orthogonality and preventing inter-carrier interference

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the base station controls transmission timing in communication terminals to receive signals at reference timing, then orthogonality is maintained, but FFT window position shifts occur when receiving interference waves from terminals communicating with surrounding base stations

Engineering Contradiction:

Improvesignal orthogonalityVSAvoidFFT window position accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The base station segments the frequency spectrum into multiple frequency bands and performs separate FFT processes for each band with individually adjusted FFT window positions. This allows the base station to maintain orthogonality for signals from its own terminals while separately handling interference waves from surrounding base stations by adjusting FFT window positions for each frequency band independently

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base station applies different FFT window positions for different frequency bands based on local interference conditions. By acquiring interference wave levels for each frequency band and selectively adjusting FFT window positions only where needed, the base station maintains signal orthogonality while compensating for interference without affecting the entire spectrum uniformly

Inventive Principle:

Principle #3Local quality

3Device complexity

If the base station performs FFT process without adjusting for interference waves from surrounding base stations, then processing is simple, but inter-carrier interference degrades communication quality

Engineering Contradiction:

Improvesignal processing complexityVSAvoidcommunication quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The base station performs interference wave level acquisition and FFT window position adjustment selectively for each frequency band based on interference conditions. Instead of uniformly processing all frequency bands with maximum complexity, the base station applies enhanced processing only where interference is detected, maintaining communication quality while avoiding unnecessary complexity in interference-free bands

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9172576B2Base station and method of adjusting reference timing on base station

Publication Date: 2015.10.27 KYOCERA CORP

AI summary

An FFT processing unit performs an FFT process on an OFDM signal received by a reception unit. Based on an output signal of the FFT processing unit, an interference wave level acquisition unit obtains a signal level of an interference wave in a unit radio resource not used by the base station with respect to each of a plurality of candidate timings for the reference timing in the base station. A reference timing adjustment unit determines a new timing of the reference timing from the plurality of candidate timings based on the signal level of the interference wave obtained by the interference wave level acquisition unit.