Cross Cell Beam Persistence for Asymmetric MIMO Handovers

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Solution Overview

Problem

In wireless communication systems, the asymmetry between uplink and downlink channels in MIMO and non-MIMO base stations leads to challenges in handover management, as the base station providing the strongest uplink may differ from the one providing the strongest downlink, especially in heterogeneous networks with varying channel conditions.

Innovation Solution

The implementation of cross cell beam persistence techniques, where base station controllers and user devices independently determine and manage handovers by measuring signal strength and channel conditions, allowing separate handling of uplink and downlink handovers, and utilizing beamforming to extend signal coverage beyond traditional cell boundaries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional handover management is used in MIMO networks, then the handover process is simple and unified, but it cannot effectively handle the asymmetry between uplink and downlink channels, leading to suboptimal network performance

Engineering Contradiction:
Improvehandover management adaptabilityVSAvoidhandover management complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the unified handover management into separate uplink and downlink handover processes. The network side can independently control uplink handover timing and downlink handover timing, allowing each direction to be optimized according to its specific channel conditions and requirements, thereby resolving the contradiction between adaptability and complexity.

Inventive Principle:
Principle #1Segmentation

2Productivity

If separate uplink and downlink handover control is implemented, then network performance is optimized for asymmetric channels, but the handover management complexity increases

Engineering Contradiction:
Improvenetwork performanceVSAvoidhandover management complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements preliminary actions by having the network side pre-configure handover parameters, measurement configurations, and reporting criteria for both uplink and downlink before actual handover events occur. This preparation allows the system to quickly execute optimized handovers without real-time complex decision-making, thereby improving network performance while controlling management complexity.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If beamforming is used to extend signal coverage beyond cell boundaries, then signal strength and quality are maintained across cell boundaries, but the system complexity increases due to additional beam management requirements

Engineering Contradiction:
Improvesignal strength and qualityVSAvoidbeam management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges beam management with existing handover procedures by integrating beam measurement, beam reporting, and beam selection into the unified handover framework. This combination allows the system to maintain signal quality across cell boundaries using beamforming while avoiding the overhead of completely separate beam management protocols, thus improving reliability without proportionally increasing system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient and dynamic management of handovers, maintaining signal strength and quality across cell boundaries, improving network performance by allowing separate optimization of uplink and downlink channels, even in asymmetric scenarios.

Implementation Method 1

A MIMO or M-MIMO base station may use beam forming to transmit signals on the downlink to one or more user devices. In general, beam forming is shaping of an antenna beam by multiple transmit antennas in the direction of a target receiver.

Methodology Applied
Scientific EffectBeam forming: Focusing

Data Source

PatentUS9379790B2Cross cell beam persistence in a massive multiple-input, multiple output (MIMO) environment
Publication Date: 2016.06.28 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

In wireless operating environments, wireless user devices are often within the coverage area of multiple base stations. The base station providing the best uplink for the user device may be different than the base station providing the best downlink for the user device. Systems and techniques for asymmetric uplink and downlink communications for a user device are provided. In embodiments, the user device initially synchronizes with a base station. Both the uplink and downlink are initially served by this base station. A determination is then made whether to handoff the downlink for the user device to another base station. When a determination is indicated, the downlink is handed off to the second base station. Thereafter, periodic measurements are made. The determinations whether to handoff the uplink and downlink for the user device are made independently.