Downlink Transmission Indication for NR in Unlicensed Spectrum
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Solution Overview
Problem
In the LAA-LTE system, terminal devices face challenges in determining the time-frequency resources for downlink transmission in the New Radio (NR) technology, as there are no Cell-specific Reference Signals (CRS) available, which hinders correct data communication with network devices.
Innovation Solution
The proposed solution involves a method where network devices determine an available time-frequency resource and send first information to terminal devices through a downlink transmission burst, allowing the terminal devices to identify the resource and determine the starting and ending positions of the downlink transmission, using beamforming to improve signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CRS is used for downlink transmission indication in LAA-LTE system, then terminal devices can easily detect downlink transmission, but NR technology cannot use CRS and lacks a method to indicate downlink transmission resources
Solution Approach 1:
The patent extracts the essential function of CRS (indicating downlink transmission resources) and separates it from the CRS signal itself. It uses dedicated indication information carried on physical channels to convey the same functional purpose, allowing NR technology to achieve downlink transmission indication without relying on LTE-specific CRS signals.
Solution Approach 2:
The patent introduces indication information as an intermediary element that mediates between the network device's downlink transmission and the terminal device's resource identification. This indication information, carried through physical channels, serves as a bridge to convey resource allocation details without requiring direct use of CRS.
2Productivity
If network device uses opportunistic transmission on unlicensed spectrum, then spectrum utilization improves, but terminal device cannot determine when downlink transmission starts and stops
Solution Approach 1:
The patent implements a feedback mechanism where the network device sends indication information to terminal devices about downlink transmission resource allocation. This feedback loop allows terminal devices to accurately determine when downlink transmission starts and stops, even in opportunistic transmission scenarios on unlicensed spectrum, thereby preventing information loss about transmission timing.
3Loss of energy
If no indication information is sent, then signaling overhead is reduced, but terminal device cannot identify time-frequency resources for downlink transmission
Solution Approach 1:
The patent applies partial action by sending only the necessary indication information about downlink transmission resources rather than comprehensive signaling. The indication information contains precisely the needed elements (resource allocation, timing) without unnecessary overhead, achieving a balance between signaling efficiency and information completeness.
Data Source
AI summary
An information transmission method, a terminal device and a network device are provided. The method is applied to a communication system including a network device and a terminal device, and a frequency-domain resource on a carrier used by the communication system is a contention based frequency-domain resource. The method including: the network device determining an available first time-frequency resource and sending first information to the terminal device through the first time-frequency resource; the terminal device receiving first information from the network device through a first time-frequency resource, where the first time-frequency resource is a time-frequency resource in a first downlink transmission burst; and the terminal device determining, according to the first information, that the first time-frequency resource is a downlink time-frequency resource.