Subframe Indicator for Unlicensed Frequency CSI Measurement
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Solution Overview
Problem
In wireless communication systems, UEs cannot determine when to perform channel state information (CSI) measurements on unlicensed frequencies due to the lack of knowledge about channel occupation times, which affects communication quality and integration with licensed bands.
Innovation Solution
A method where a UE receives a subframe indicator from a serving cell on a licensed frequency to determine subframes occupied by an unlicensed frequency, allowing it to perform CSI measurements only during designated subframes, using a new RNTI for reference signal indications that include information on measurement subframes and cell identifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cell on unlicensed frequency transmits reference signal only during channel occupation time, then communication quality on unlicensed frequency is improved, but UE cannot perform CSI measurement because it does not know when the reference signal is transmitted
Solution Approach 1:
The patent introduces a subframe indicator as an intermediary message that bridges the gap between the network's channel occupation time information and the UE's measurement needs. This indicator is carried on the licensed frequency and provides the UE with the necessary information about which subframes contain reference signals on the unlicensed frequency, enabling CSI measurement without directly transmitting the reference signal timing information
Solution Approach 2:
The patent segments the information transmission by separating the control information (subframe indicator) from the data information (reference signal). The subframe indicator is transmitted on the licensed frequency to provide timing information, while the reference signal is transmitted only on the unlicensed frequency during channel occupation time, allowing the UE to perform measurements without knowing the channel occupation time in advance
2Adaptability or versatility
If UE performs CSI measurement on unlicensed frequency without knowing channel occupation time, then measurement flexibility is improved, but measurement accuracy deteriorates due to inability to determine when reference signal is transmitted
Solution Approach 1:
The patent applies preliminary action by having the network transmit the subframe indicator before the actual reference signal transmission on the unlicensed frequency. This indicator provides the UE with advance knowledge of which subframes will contain reference signals, allowing the UE to prepare and perform measurements accurately during the indicated subframes without sacrificing measurement flexibility
3Productivity
If LTE and WLAN are integrated in unlicensed band, then network capacity is improved, but network integration complexity increases due to different network structures
Solution Approach 1:
The patent uses the licensed frequency as an intermediary layer that manages the integration between LTE and WLAN networks. By transmitting control information (subframe indicators) on the licensed frequency, the system can coordinate measurements and resource allocation across both networks without requiring direct integration of their different structures, thus reducing integration complexity while maintaining improved network capacity
Solution Approach 2:
The patent makes the licensed frequency serve multiple functions: it acts as both a communication carrier and a control channel for managing unlicensed frequency resources. The subframe indicator mechanism allows the licensed frequency to universally manage both LTE operations and WLAN integration, simplifying the overall network architecture by providing a unified control plane
Data Source
AI summary
A method for performing, by a terminal, communication using an unlicensed frequency in a wireless communication system, and an apparatus supporting the same are provided. The terminal may receive, from a serving cell on a licensed frequency, a subframe indicator indicating a subframe which is occupied by an unlicensed frequency, and may determine, on the basis of the received subframe indicator, the subframe which is occupied by an unlicensed frequency. Another method for performing, by a terminal, communication using an unlicensed frequency in a wireless communication system is provided. A PDCCH of a serving cell is monitored using a new radio network temporary identifier (RNTI); a reference signal indication is received from the monitored PDCCH of the serving cell; and a subframe which is occupied by an unlicensed frequency is determined on the basis of the received reference signal indication, wherein the new RNTI may be an RNTI which has been newly established in the terminal in order to receive the reference signal indication from the PDCCH.