Partial Subframe PDCCH Reception in Unlicensed Band
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems supporting unlicensed bands, user equipment (UE) face challenges in receiving downlink signals efficiently when there is uncertainty about the transmission of partial subframes, leading to potential misinterpretation of scheduling information.
Innovation Solution
A method where the UE receives uplink scheduling information via a partial subframe by checking for specific Physical Downlink Control Channel (PDCCH) indications in both the previous and current subframes, ensuring accurate reception of UL grants even if the downlink signal is not transmitted in a partial symbol of the current subframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE monitors for PDCCH indications in both N-1th and Nth subframes to determine partial subframe configuration, then the reliability of downlink signal reception is improved, but the device complexity and processing overhead increase
Solution Approach 1:
The base station transmits PDCCH indications in the N-1th subframe (previous subframe) to inform the UE about the partial subframe configuration that will be used in the Nth subframe (current subframe). This preliminary action allows the UE to prepare for the upcoming partial subframe reception, knowing in advance whether a downlink signal will be transmitted and in which symbols, thereby improving reception reliability without requiring complex real-time detection mechanisms.
2Productivity
If the base station transmits downlink signals in partial subframes with LBT-based signal transmission, then the productivity of unlicensed band utilization is improved, but the reliability of signal transmission deteriorates due to channel access uncertainty
Solution Approach 1:
The base station uses LBT (Listen-Before-Talk) to sense the channel status before transmitting downlink signals in unlicensed bands. Based on the channel availability feedback from the LBT procedure, the base station dynamically determines whether to transmit the downlink signal in the partial subframe and informs the UE through PDCCH indications. This feedback mechanism allows the system to adapt to channel conditions, improving productivity by utilizing available unlicensed spectrum while maintaining reliability through informed transmission decisions.
Data Source
AI summary
A method for receiving a downlink signal by a user equipment (UE) in a wireless communication system supporting an unlicensed band, includes monitoring a set of Physical Downlink Control Channel (PDCCH) candidates for receiving a PDCCH in subframe # n−1 of the unlicensed band, wherein n is an integer larger than 1; receiving a first PDCCH in subframe # n of the unlicensed band, wherein the first PDCCH includes information for indicating that a number of occupied symbols in the subframe # n is less than 14; and receiving, from a base station (BS), a second PDCCH including uplink scheduling information in the subframe # n based on that the UE does not receive the PDCCH in the subframe # n−1 and receives the first PDCCH.