Direct UE Timing Alignment in LTE Inter-Device Sessions

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Solution Overview

Problem

In LTE systems, time misalignment between User Equipment (UE) devices during direct UE-to-UE communication leads to inter-symbol and inter-carrier interference, causing performance degradation, which existing methods fail to adequately address.

Innovation Solution

The method involves compensating for timing misalignment by adjusting receive and transmit timing, adding guard periods or subcarriers, and avoiding allocation of resources in the Physical Downlink Control Channel (PDCCH) to minimize interference, using timing reference signals and propagation delays to align subframes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If direct UE-to-UE communication is implemented in LTE systems, then device-to-device communication capability is improved, but timing misalignment causes inter-symbol and inter-carrier interference leading to performance degradation

Engineering Contradiction:

Improvedirect communication capabilityVSAvoidcommunication performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The transmitting UE performs timing advance adjustment before direct communication to pre-align its timing with the receiving UE, preventing timing misalignment interference from occurring in the first place

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the traditional eNB-centric timing alignment mechanism with a UE-autonomous timing adjustment mechanism, where UEs directly measure and compensate for timing differences without requiring eNB intervention

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If timing alignment is performed in closed loop manner using timing advance commands, then timing alignment accuracy is improved, but signaling overhead and system complexity increase

Engineering Contradiction:

Improvetiming alignment accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The transmitting UE autonomously measures the timing difference with the receiving UE and adjusts its own transmission timing without requiring external timing advance commands, making the system self-regulating

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the timing alignment function from the eNB and transfers it to the UEs themselves, removing the need for closed-loop timing advance signaling and reducing system complexity

Inventive Principle:

Principle #2Taking out (Extraction)

3Object-affected harmful factors

If guard periods are added to subframes to compensate for timing misalignment, then interference reduction is improved, but resource efficiency deteriorates due to wasted time resources

Engineering Contradiction:

Improveinterference reductionVSAvoidresource efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The transmitting UE performs timing advance adjustment before direct communication to pre-align its timing with the receiving UE, eliminating the need for guard periods and maximizing resource utilization

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2982196B1Aligning timing for direct communications

Publication Date: 2019.06.12 BLACKBERRY LTD

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AI summary

In some implementations, a method includes compensating for timing misalignment of subframes associated with at least one of first user equipment (UE) or a second UE. The first UE and the second UE are in an inter-device session (IDS) for direct UE-to-UE communication, and timing for the first UE and a timing for the second UE is derived from an eNode B (eNB).