5G LBT Time Offset Signaling for SS Burst Rate Matching
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Solution Overview
Problem
In 5G communications systems, the reliability of downlink data parsing is compromised due to the impact of Listen Before Talk (LBT) channel contention access mechanisms, particularly on unlicensed bands, where network devices may not send synchronization signal burst sets (SS Burst Sets) at configured transmission times, leading to inaccurate time-frequency resource allocation and parsing of downlink data.
Innovation Solution
A communication method where network devices perform LBT on carriers to determine time offsets between actual and configured transmission times of SS Burst Sets, and send these offsets to terminals, allowing terminals to adjust their rate matching and accurately parse downlink data, thereby improving system reliability. Additionally, the method involves skipping or sending time offsets based on preset relationships between time offsets to reduce signaling overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LBT channel contention access mechanism is used on unlicensed bands, then the network device can access the channel, but the actual transmission time of SS Burst Set deviates from configured transmission time, causing inaccurate downlink data parsing
Solution Approach 1:
The network device sends time offset information to the terminal, providing feedback about the actual transmission time deviation. The terminal uses this feedback to adjust its rate matching process, ensuring accurate downlink data parsing despite LBT-induced timing deviations.
Solution Approach 2:
The network device performs LBT and determines the time offset before transmitting the SS Burst Set. By preparing the time offset information in advance and sending it to the terminal, the system ensures the terminal can correctly align its reception timing before actual data transmission occurs.
2Reliability
If time offset information is sent for every carrier, then the terminal can accurately parse downlink data on each carrier, but signaling overhead increases
Solution Approach 1:
When multiple carriers have the same time offset value, the network device sends a single time offset indicator that applies to all such carriers. This merging approach reduces signaling overhead while maintaining accurate timing alignment across multiple carriers through unified time offset indication.
Solution Approach 2:
The time offset indication mechanism serves multiple functions: it provides timing correction for individual carriers when needed, and simultaneously provides unified timing correction for multiple carriers when their offsets are identical. This multi-functionality reduces the need for separate signaling for each carrier.
Data Source
AI summary
This application provides a communications method, which includes: performing, by a network device, LBT on a first carrier, and determining a time offset when the LBT is completed, where the first carrier is used to send a first SS Burst Set, and the time offset is a time offset of an actual transmission time of the first SS Burst Set on the first carrier relative to a configured transmission time of the first SS Burst Set; sending, by the network device, the time offset to a terminal; and receiving, by the terminal, the time offset, and performing rate matching on the first carrier based on the time offset. Thus, the terminal may determine the actual transmission time of the first SS Burst Set based on the time offset, to perform the rate matching and accurately parse downlink data, thereby improving reliability of a communications system.