Unlicensed Band LTE-WLAN Coexistence via Preamble Coordination

Solution Overview

Problem

The increasing demand for mobile data and frequency resources in wireless communications, particularly due to the rise of smartphones, strains communication networks, leading to difficulties in managing frequency distribution and maintaining communication quality, especially when using licensed frequency schemes. The integration of LTE and WLAN systems in unlicensed bands is challenging due to handover and quality of service (QoS) issues.

Innovation Solution

A method and apparatus for transmitting downlink data in an unlicensed band, incorporating a WLAN preamble, PDCCH data, and PDSCH data, which includes information on time resources and control/data traffic, to avoid collisions between LTE and WLAN systems, allowing coexistence and efficient data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If LTE and WLAN systems are integrated in unlicensed bands, then data capacity is extended and network strain is alleviated, but collisions between systems occur and communication quality deteriorates

Engineering Contradiction:

Improvedata capacityVSAvoidcommunication quality

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The downlink subframe is segmented into multiple regions with different functions: WLAN preamble region for channel access coordination, PDCCH region for control information, and PDSCH region for data transmission. This segmentation allows LTE and WLAN systems to operate in the unlicensed band simultaneously with reduced interference by assigning specific time-frequency resources to each system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The WLAN preamble is transmitted before the LTE downlink data in the time domain. This preliminary action allows WLAN systems to detect the upcoming LTE transmission and avoid channel access during this period, preventing collisions and ensuring that LTE transmissions can proceed without interference from WLAN systems.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If exclusive frequency usage rights are ensured through auction, then communication quality is maintained, but capacity off-loading to WLAN becomes difficult

Engineering Contradiction:

Improvecommunication qualityVSAvoidfrequency resource flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The base station performs multiple functions using the same unlicensed frequency resources: it transmits both LTE downlink signals and WLAN preambles, and coordinates with both LTE user equipment and WLAN access points. This multi-functionality allows the system to maintain exclusive frequency usage rights while enabling capacity off-loading to WLAN networks.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The WLAN preamble acts as an intermediary signal that bridges LTE and WLAN systems. It carries information about upcoming LTE transmissions, allowing WLAN systems to coordinate their channel access and avoid collisions, thus enabling flexible frequency resource usage while maintaining communication quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If LTE system transmits downlink data in unlicensed band, then data traffic is off-loaded from licensed band, but collisions with WLAN systems occur

Engineering Contradiction:

Improvedata transmission efficiencyVSAvoidinterference and collisions

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The WLAN preamble is transmitted before the LTE downlink data in the time domain. This preliminary action allows WLAN systems to detect the upcoming LTE transmission and avoid channel access during this period, preventing collisions and ensuring that LTE transmissions can proceed without interference from WLAN systems.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The WLAN preamble acts as an intermediary signal that bridges LTE and WLAN systems. It carries information about upcoming LTE transmissions, allowing WLAN systems to coordinate their channel access and avoid collisions, thus enabling flexible frequency resource usage while maintaining communication quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10200224B2Method and apparatus for transmitting data in non-licensed band

Publication Date: 2019.02.05 LG ELECTRONICS INC

AI summary

Disclosed is a method and apparatus for transmitting data in a non-licensed band. The method of transmitting downlink data in the non-licensed band may comprise the steps of: generating, by a base station, downlink data and transmitting the downlink data to a terminal through a downlink subframe. The downlink data may comprise wireless LAN preamble, PDCCH data, and PDSCH data. The wireless LAN preamble may comprise information on time resources for communication between the base station and the terminal, and the PDCCH data may comprise control data for the terminal. Also, the PDSCH data may comprise traffic data for the terminal.