LTE-U Synchronization Signal Relocation for Unlicensed Coexistence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of LTE-U networks into unlicensed frequency bands poses challenges for coexistence with incumbent technologies and other LTE operators, leading to interference issues that violate regulatory requirements.
Innovation Solution
The solution involves inhibiting the transmission of synchronization signals like PSS, SSS, and CRS on unlicensed carriers, and using RRC signaling from licensed carriers to provide system information, thereby reducing interference and enabling fair coexistence with other technologies and LTE operators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization signals (PSS, SSS, CRS) are transmitted on unlicensed carriers, then LTE-U network can provide time and frequency synchronization, but interference with incumbent technologies and other LTE operators increases
Solution Approach 1:
The patent extracts the synchronization signal transmission function from the unlicensed carrier and relocates it to the licensed carrier. The eNB transmits PSS, SSS, and CRS only on licensed carriers, while unlicensed carriers are used solely for data transmission, thereby eliminating synchronization-related interference with incumbent technologies and other LTE operators operating in the unlicensed band.
Solution Approach 2:
The licensed carrier acts as an intermediary that provides synchronization services to UEs without causing interference in the unlicensed band. By using the licensed carrier as a mediator for synchronization signal transmission, the system maintains synchronization capability while avoiding harmful interactions with other technologies sharing the unlicensed spectrum.
2Adaptability or versatility
If LTE-U network uses unlicensed spectrum, then service offering is augmented, but coexistence with incumbent technologies becomes difficult due to interference
Solution Approach 1:
The patent segments the carrier functions by separating synchronization signal transmission (PSS, SSS, CRS) from data transmission. Licensed carriers handle synchronization and control functions, while unlicensed carriers are dedicated to data transmission only. This segmentation allows LTE-U to utilize unlicensed spectrum for capacity enhancement without causing synchronization interference to incumbent technologies.
Solution Approach 2:
Different carriers are assigned different functional qualities: licensed carriers provide synchronization and control services, while unlicensed carriers provide data transmission services. This local quality differentiation ensures that each carrier type performs its specific function optimally without creating interference in frequency bands where other technologies operate.
3Productivity
If multiple LTE operators use the same unlicensed spectrum, then network capacity increases, but self-coexistence among different LTE operators deteriorates
Solution Approach 1:
The patent extracts synchronization signal transmission from unlicensed carriers and places it exclusively on licensed carriers. This extraction eliminates the source of interference that would otherwise occur between multiple LTE operators using the same unlicensed spectrum, thereby improving self-coexistence while maintaining network capacity benefits.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Described is an Evolved Node-B (eNB) to communicate with one or more User Equipment (UEs) on a Long Term Evolution (LTE) network operating in an unlicensed spectrum, the eNB comprising hardware processing circuitry including: an antenna; and a transmitter, coupled to the antenna, the transmitter operable to: inhibit transmission of system information to a UE when the spectrum is unlicensed. The transmitter may also be operable to: refrain from transmission of one or more synchronization signals to a UE when a spectrum is unlicensed. The transmitter may also be operable to transmit the one or more synchronization signals in frequencies away from the centers of the six PRBs of the transmission bandwidth. The transmitter may also be operable to: turn off transmitting in the unlicensed spectrum when the eNB is not servicing any UE; and turn on transmitting in the unlicensed spectrum when a UE is discovered.