Small Cell Discovery via Periodic Signal Forwarding

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Solution Overview

Problem

In LTE dense deployment scenarios, small cells in an off state cannot be discovered by user equipment due to the absence of air-interface signals, hindering efficient handover and power management.

Innovation Solution

A method where a base station of a servicing small cell receives and forwards a physical cell identifier and status parameters from a neighboring non-servicing small cell, indicating the mode and timing of air-interface signal transmission, allowing user equipment to detect and measure the signals of dormant small cells, and potentially awaken them for better signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If small cells are kept in off state to save power consumption, then power consumption is reduced, but user equipment cannot discover these small cells for handover

Engineering Contradiction:

Improvepower consumptionVSAvoidsmall cell discoverability

Core Design Contradiction:

Loss of energyVSLoss of information

Solution Approach 1:

The patent implements periodic on/off cycling of small cells where dormant small cells periodically transmit discovery signals at predetermined intervals. This allows user equipment to discover and measure these cells during their active transmission windows while maintaining overall power savings when cells are dormant. The periodic transmission resolves the contradiction by providing discoverability information at specific time intervals rather than continuous transmission.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent enables user equipment to perform measurements and evaluations of dormant small cells during their periodic active phases before they are fully activated for service. The UE can pre-assess signal quality (RSRP/RSRQ) and report to the network, allowing the network to make informed decisions about which dormant cells to activate for handover. This preliminary measurement action resolves the information loss by gathering data about dormant cells in advance.

Inventive Principle:

Principle #10Preliminary action

2Loss of information

If small cells transmit air-interface signals continuously to enable discovery, then small cell discoverability is improved, but power consumption increases

Engineering Contradiction:

Improvesmall cell discoverabilityVSAvoidpower consumption

Core Design Contradiction:

Loss of informationVSUse of energy by moving object

Solution Approach 1:

Instead of continuous signal transmission, the patent implements periodic transmission of discovery signals by dormant small cells at predetermined intervals and time slots. This allows user equipment to discover these cells during their active transmission windows while maintaining overall power savings when cells are dormant. The periodic transmission resolves the contradiction by providing discoverability information at specific time intervals rather than continuous transmission.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies partial action by having dormant small cells transmit only essential discovery signals (synchronization signals, reference signals) at reduced power and specific time intervals, rather than full-service continuous transmission. This partial transmission provides sufficient information for UE discovery and measurement while consuming significantly less power than continuous operation.

Inventive Principle:

Principle #16Partial or excessive action

3Loss of information

If dormant small cells periodically send air-interface signals, then user equipment can discover and measure them, but interference may occur among small cells

Engineering Contradiction:

Improvesmall cell discoverabilityVSAvoidinterference among small cells

Core Design Contradiction:

Loss of informationVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent introduces dynamic time-domain scheduling where the network can configure different periodicities, time offsets, and durations for discovery signal transmission by different dormant small cells. This dynamic configuration allows the network to coordinate transmissions to avoid simultaneous activation of neighboring dormant cells, thereby reducing inter-cell interference during discovery phases.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3154282B1Small cell discovery method and system, base station, and user equipment

Publication Date: 2019.03.27 CHINA MOBILE COMM GRP CO LTD

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AI summary

Disclosed is a small cell discovery method, the method including: a base station of the current service cell receives a physical cell identifier and a status parameter transmitted by a base station of a non-service cell adjacent to the current service cell, the status parameter being used to indicate a mode of transmitting an air interface signal by the base station of the non-service cell; the base station of the current service cell transmits the physical cell identifier and the status parameter to a user equipment. Also, disclosed are a base station, a user equipment and a small cell discovery system.