Small Cell Discovery in Heterogeneous Networks

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Solution Overview

Problem

In heterogeneous networks, user equipment (UE) experiences high power consumption and delayed transitions to small cells due to inefficient small cell discovery processes, leading to sub-optimal data throughput and battery life issues, especially when searching for pico cells with different carrier frequencies.

Innovation Solution

The method involves a user equipment (UE) in a heterogeneous network receiving measurement restrictions, small cell lists, and configuration information from a macro cell to optimize small cell discovery, utilizing broadcast and dedicated signaling for efficient neighbor cell measurements and attachment, and applying s-measure offset values for neighbor cell discovery, thereby reducing unnecessary measurements and improving battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE periodically searches for small cells to preserve battery life, then power consumption is reduced, but the transition to small cells is delayed leading to sub-optimal data throughput

Engineering Contradiction:
Improvepower consumptionVSAvoiddata throughput
Core Design Contradiction:
Use of energy by moving objectVSProductivity

Solution Approach 1:

The network provides the UE with pre-configured small cell lists and measurement restrictions before the UE needs to discover small cells. This preliminary provision of information allows the UE to quickly identify and transition to small cells when needed, rather than performing exhaustive periodic searches, thus maintaining high data throughput while reducing power consumption.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The network acts as an intermediary by providing measurement restrictions and small cell lists to the UE. This intermediary information guide the UE's search process, enabling efficient small cell discovery without requiring the UE to perform exhaustive scans, thereby resolving the contradiction between power saving and fast transition.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the UE scans for reference signals to discover small cells, then small cell discovery is enabled, but UE power consumption increases

Engineering Contradiction:
Improvesmall cell discoveryVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The search space is segmented by providing the UE with specific small cell lists and measurement restrictions instead of requiring a comprehensive scan of all possible frequencies and cells. This segmentation limits the UE's measurement activities to only relevant small cells, enabling reliable discovery while significantly reducing power consumption.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of performing exhaustive measurements on all possible frequencies and cells, the UE performs partial measurements only on the restricted set of small cells provided by the network. This partial action is sufficient for reliable small cell discovery in the UE's current location while avoiding the excessive power consumption of complete scans.

Inventive Principle:
Principle #16Partial or excessive action

3Adaptability or versatility

If the UE searches for pico cells on different carrier frequencies, then small cell discovery capability is improved, but power consumption and measurement complexity increase

Engineering Contradiction:
Improvesmall cell discovery capabilityVSAvoidpower consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The network provides preliminary information including small cell lists with carrier frequency details and measurement restrictions before the UE needs to discover small cells. This advance provision enables the UE to efficiently search only on relevant frequencies without exhaustive scanning, maintaining multi-frequency discovery capability while reducing power consumption.

Inventive Principle:
Principle #10Preliminary action

4Measurement precision

If the UE performs exhaustive small cell searches, then transition accuracy is improved, but transition time increases

Engineering Contradiction:
Improvetransition accuracyVSAvoidtransition time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The network provides pre-configured small cell lists and measurement restrictions before the UE needs to transition. This preliminary information allows the UE to quickly identify suitable small cells and perform accurate measurements only on relevant cells, achieving high transition accuracy without the time penalty of exhaustive searches.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2761821B1Method and apparatus for small cell discovery in heterogeneous cellular networks
Publication Date: 2018.02.21 BLACKBERRY LTD
  • EP2761821B1 patent drawingFigure 1
  • EP2761821B1 patent drawingFigure 2
  • EP2761821B1 patent drawingFigure 3

AI summary

A method and a user equipment in a network having a macro cell and at least one small cell, the method in one embodiment receiving a measurement restriction over a broadcast channel from the macro cell; and applying the restriction for a corresponding measurement at the user equipment. In one embodiment the method includes receiving a small cell list from the macro cell; and measuring at least one of a reference signal receive power and a reference signal received quality based on the received small cell list. The method includes, in one embodiment, receiving a neighboring small cell configurations from the macro cell; and utilizing the received small cell configurations to attach to a small cell. The method includes, in one embodiment, receiving an s-measure offset value over a broadcast channel from the macro cell; and applying the s-measure offset value to an s-measure for neighbor cell discovery.