NB-IoT NPRACH Open-Loop Power Control to Reduce Interference
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Solution Overview
Problem
In interference-limited communications networks or networks with heavy load, the existing method for determining transmit power in Narrowband Internet of Things (NB-IoT) systems exacerbates signal interference between terminal devices, particularly on the narrowband physical random access channel (NPRACH).
Innovation Solution
A terminal device determines a transmit power less than the maximum based on its access status and power control parameters, such as downlink path loss and RSRP, using open-loop power control to reduce interference, and a network device provides indication information for power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminal devices directly use maximum transmit power to send signals on NPRACH, then signal coverage is improved, but interference between terminal devices is aggravated
Solution Approach 1:
The patent changes the transmit power parameter from a fixed maximum value to a dynamically determined value based on path loss measurements. Terminal devices calculate appropriate transmit power levels considering their specific channel conditions, thereby maintaining sufficient signal coverage while reducing excessive power transmission that causes interference to other devices.
Solution Approach 2:
The patent implements a feedback mechanism where terminal devices measure downlink path loss and use this information to adjust their uplink transmit power. The network device provides path loss thresholds and power control parameters, creating a closed-loop system that adapts transmit power to actual channel conditions, balancing coverage and interference reduction.
2Adaptability or versatility
If open-loop power control is used to determine transmit power, then adaptability to channel conditions is improved, but complexity of power control mechanism increases
Solution Approach 1:
The patent uses open-loop power control where terminal devices determine transmit power based on measured path loss and predetermined power control parameters. This approach provides adaptability to channel conditions without requiring complex closed-loop feedback mechanisms, as the power calculation is performed locally using readily available measurements and network-provided parameters.
Data Source
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AI summary
This application provides a signal transmission method, a terminal device, and a network device. The method includes: determining, by a terminal device, a first transmit power based on an access status of the terminal device at a current coverage level and/or a first power control parameter; and transmitting a signal at the first transmit power. According to the signal transmission method, the terminal device, and the network device in the embodiments of this application, interference to uplink transmission of another terminal device can be reduced.