Unlicensed Spectrum Data Transmission via Preamble-Data Merging
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Solution Overview
Problem
In LTE systems, the unlicensed spectrum is used as a secondary carrier, but its discontinuous nature and the need for anchoring to a licensed spectrum lead to inefficient spectrum utilization due to the waste of resources caused by the preamble signal occupying channels without allowing data or scheduling information transmission.
Innovation Solution
A base station determines a time-domain interval of available unlicensed spectrum resources, sends a preamble signal in a first subframe, and then transmits downlink control information and data, ensuring that data is sent within the first subframe to improve spectrum utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a preamble signal is sent to occupy the unlicensed spectrum channel, then channel access is secured, but data transmission is blocked during the preamble occupation period
Solution Approach 1:
The patent merges the preamble function with the data transmission function by allowing data to be transmitted in the same subframe where the preamble is sent. The base station sends the preamble in the first subframe of an available time-domain interval and simultaneously transmits downlink control information and data in the same subframe, combining channel occupation with productive data transmission.
Solution Approach 2:
The patent ensures continuous useful action by transmitting data immediately after the preamble within the same available time-frequency resources. The base station determines a time-domain interval of available resources and continuously utilizes these resources for both preamble transmission and data transmission without idle gaps, maximizing spectrum utilization.
2Quantity of substance
If the unlicensed spectrum is used as a secondary carrier, then spectrum resources are expanded, but discontinuous availability reduces transmission reliability
Solution Approach 1:
The patent applies preliminary action by having the base station perform clear channel assessment (CCA) or extended CCA (ECCA) before transmitting data on the unlicensed spectrum. The base station listens to the channel for at least 20 μs to determine if it is idle, and only after confirming channel availability does it proceed with preamble and data transmission, ensuring reliable access to discontinuous spectrum resources.
Solution Approach 2:
The patent introduces dynamics by making the unlicensed spectrum usage adaptive rather than fixed. The base station dynamically determines time-domain intervals of available resources based on channel conditions and LBT outcomes, adjusting transmission timing and duration to match actual spectrum availability, thereby maintaining reliability despite discontinuous resource characteristics.
3Reliability
If CCA or ECCA listening is performed for 20 μs or more, then channel access reliability is improved, but transmission delay increases
Solution Approach 1:
The patent applies parameter changes by allowing the base station to adjust the listening duration parameter based on channel conditions. The base station can perform CCA for at least 20 μs or switch to ECCA with continuous listening for R time periods, dynamically changing the listening parameter to balance reliability requirements with delay constraints. Once the channel is confirmed idle, transmission begins immediately to minimize delay.
Data Source
AI summary
A data transmission method and an apparatus are provided. The method includes: determining, by a base station, a time-domain interval of available time-frequency resources in an unlicensed spectrum, where the available time-frequency resources are continuous time-frequency resources in a time domain; sending, by the base station, a preamble signal in a first subframe in the interval, where the first subframe is an initial subframe in the interval; and sending, by the base station, downlink control information and data after sending the preamble signal, where the data is in the first subframe, the downlink control information includes scheduling indication information, and the scheduling indication information is used to indicate a frequency-domain location of the data. According to the present invention, spectrum utilization can be improved.