Discovery Reference Signal Configuration for Unlicensed Spectrum Access
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Solution Overview
Problem
The current 5G NR system lacks a reference signal configured for synchronization and access in unlicensed frequency spectrum, leading to low accuracy of reference signal reception and hindered synchronization and channel access by user equipment.
Innovation Solution
Determining and transmitting Discovery Reference Signals (DRS) in specific time and frequency domains, including Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH), Demodulation Reference Signal (DMRS), and Channel State Information Reference Signal (CSI-RS), to facilitate synchronization and access in unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference signal is configured as periodic signal to facilitate UE access and acquire radio frame information, then synchronization capability is improved, but spectrum resource occupation increases and may cause transmission interruptions in unlicensed spectrum
Solution Approach 1:
The patent applies periodic action by configuring the reference signal as a periodic signal with specific periodicity (e.g., 5ms, 10ms, 20ms). This allows the reference signal to be transmitted at regular intervals, ensuring that UE can periodically synchronize with the network while occupying spectrum resources only when needed, thus balancing synchronization reliability with spectrum resource efficiency in unlicensed bands
Solution Approach 2:
The patent implements preliminary action by performing Listen-Before-Talk (LBT) procedure before transmitting the periodic reference signal. The base station checks whether the spectrum is idle prior to transmission, and only transmits the reference signal when the channel is clear. This preliminary channel assessment prevents transmission collisions and ensures continuous reference signal transmission for UE synchronization without wasting spectrum resources on failed transmissions
2Duration of action of stationary object
If Listen-Before-Talk (LBT) is used to occupy spectrum resources for continuous reference signal transmission, then transmission continuity is improved, but access delay increases due to channel sensing requirement
Solution Approach 1:
The patent applies preliminary action by performing LBT channel sensing before each reference signal transmission opportunity. The base station senses the channel in advance of the scheduled reference signal transmission, and if the channel is clear, immediately transmits the reference signal. This minimizes the time penalty of LBT by performing sensing as early as possible without delaying the actual transmission, thus maintaining transmission continuity while reducing access delay
Solution Approach 2:
The patent ensures continuity of useful action by configuring the reference signal with appropriate periodicity and using LBT to maintain continuous transmission opportunities. The base station continuously monitors the channel and transmits reference signals at scheduled intervals whenever the channel is available, ensuring that UE can continuously synchronize without long interruptions, thus maintaining transmission continuity while managing access delay through efficient channel access
Data Source
AI summary
There is provided a method for transmitting a reference signal. The method for transmitting the reference signal includes: determining locations in time and frequency domains of a DRS, the DRS comprising at least one of a PSS, an SSS, a PBCH, a DMRS for PBCH, a CSI-RS for TRS, a CSI-RS for beam management, and a CSI-RS for acquiring channel state information; and transmitting the DRS at the determined locations in time and frequency domains of the DRS.