Unlicensed Spectrum Synchronization via Discovery Reference Signal Timing
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Solution Overview
Problem
In standalone LTE-U systems, there is a challenge in establishing effective communication between base stations and user equipment without assistance from licensed spectra, as existing technologies lack a standardized method for synchronizing transmission timing of discovery reference signals in unlicensed frequency bands, leading to inefficiencies and potential interference.
Innovation Solution
The system introduces a method where the base station transmits timing information for the discovery reference signals to user equipment, allowing them to identify transmission subframes within a specific range, enabling synchronized communication even without a licensed spectrum PCell, and optionally uses broadcast signals to convey this information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station transmits discovery reference signals periodically in unlicensed spectrum without standardized timing synchronization, then the transmission opportunities are increased, but interference between multiple base stations and user equipment synchronization difficulty increases
Solution Approach 1:
The patent implements periodic transmission of discovery reference signals at standardized intervals (e.g., 40ms or 80ms periods) in unlicensed spectrum. This periodic action allows multiple base stations to coordinate their transmissions systematically, reducing random interference while maintaining adequate transmission opportunities. The periodic structure enables user equipment to predict and synchronize to these signals effectively.
Solution Approach 2:
The patent introduces configurable timing parameters including transmission periodicity (40ms/80ms), subframe offsets, and timing advance values that can be adjusted based on deployment scenarios. By changing these temporal parameters, the system optimizes the balance between transmission opportunities and interference reduction, allowing flexible adaptation to different unlicensed spectrum environments.
2Ease of operation
If the base station uses fixed transmission timing for discovery reference signals, then synchronization is simplified, but adaptability to different unlicensed spectrum conditions is reduced
Solution Approach 1:
The patent implements dynamic timing configuration where transmission parameters such as periodicity, subframe offsets, and timing advance values can be adjusted based on actual unlicensed spectrum conditions. The base station can dynamically modify these parameters in response to LBT outcomes, channel measurements, and traffic conditions while maintaining standardized signal structures that user equipment can synchronize to.
Solution Approach 2:
The patent introduces multiple configurable parameters including transmission periodicity (40ms or 80ms), subframe position offsets, and timing advance values that can be changed adaptively. These parameter changes enable the system to maintain standardized synchronization procedures while adapting to varying unlicensed spectrum conditions, traffic patterns, and deployment scenarios.
3Reliability
If the base station performs LBT before each discovery reference signal transmission, then channel access compliance is improved, but transmission timing uncertainty and complexity increase
Solution Approach 1:
The patent performs LBT (Listen-Before-Talk) procedures in advance of the scheduled discovery reference signal transmission times. By conducting channel access checks preliminarily at standardized intervals, the base station ensures compliance with unlicensed spectrum regulations while maintaining predictable transmission timing. The LBT outcome determines whether the pre-scheduled transmission proceeds or is deferred to the next periodic opportunity.
Data Source
AI summary
User equipment, an apparatus configured to control user equipment, and a method. The method may include receiving by a user equipment from a base station, a synchronization signal and a master information block, the master information block transmitted at a same transmission cycle as a transmission cycle of the synchronization signal. The method may further include receiving by the user equipment from the base station, first information indicating time domain positions at which the synchronization signal and the master information block are to be transmitted. In addition, the method may include receiving by the user equipment from the base station, second information indicating a periodicity of transmission of the synchronization signal and the master information block. The periodicity indicated by the second information may be different from 40 ms.