Receiver-Assisted Shared Spectrum Access for Directional Interference
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Solution Overview
Problem
Communications in shared or unlicensed spectrum face degraded performance due to unpredictable interferences, particularly in high-frequency bands, where a transmitter may mistakenly assume a channel is clear for directional transmission, while the receiver experiences interference from undetected directional transmissions.
Innovation Solution
Implement a receiver-assisted channel access mechanism where a gNB sends DCI to trigger UE to measure channel resources, generating a measurement report based on received energy, which the gNB uses to determine whether to transmit data, and optionally retransmit if interference is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmitter performs clear channel assessment (CCA) before transmission in shared spectrum, then the transmitter can detect ongoing transmissions and avoid interference, but the transmitter may still miss directional transmissions due to limited sensing capability
Solution Approach 1:
The patent introduces an intermediary measurement resource (CSI-IM resource) that acts as a mediator between the transmitter and receiver for interference detection. The receiver uses this dedicated resource to measure interference levels and report back to the transmitter, enabling more accurate detection of ongoing transmissions without requiring the transmitter to perform complex omnidirectional sensing.
Solution Approach 2:
The patent implements a feedback mechanism where the receiver measures interference on CSI-IM resources and reports the measurements back to the transmitter. This feedback loop allows the transmitter to make informed decisions about whether to proceed with transmission, significantly improving reliability by utilizing the receiver's superior channel knowledge and sensing capability.
2Productivity
If the transmitter transmits data in shared spectrum without receiver assistance, then the transmission process is simple and fast, but interference from undetected directional transmissions causes data loss
Solution Approach 1:
The patent applies preliminary action by having the receiver perform interference measurements on CSI-IM resources before the transmitter sends data. The receiver reports these measurements in advance, allowing the transmitter to determine whether the channel is suitable for transmission before actually transmitting data, thus preventing data loss while maintaining efficient transmission when conditions are favorable.
3Reliability
If the receiver measures interference on dedicated resources and reports to the transmitter, then transmission reliability improves, but the system complexity and signaling overhead increase
Solution Approach 1:
The patent makes the CSI-IM resource multi-functional by using it both for channel state information measurement and for interference measurement in shared spectrum. This universal resource serves multiple purposes, reducing the need for separate dedicated measurement resources and thereby limiting the increase in system complexity while still achieving improved transmission reliability.
Data Source
AI summary
An access node such as a gNB, when determining that a communication channel in a shared spectrum is clear, may send downlink control information (DCI) triggering a user equipment (UE) to measure a resource to determine whether the communication channel is available for the UE. The UE, triggered by the DCI, may measure received energy on resource, generate a measurement report and send the measurement report to the access node. The access node may determine whether to transmit data to the UE in the communication channel based on the measurement report.