Network Device Uplink Timing Synchronization for 5G NR
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Solution Overview
Problem
In wireless communications systems, the 5G NR system's uplink coverage is limited due to asynchronous downlink and uplink transmissions, preventing terminal devices from determining the correct uplink subframe number and causing transmission failures when NR and LTE systems share a frequency band.
Innovation Solution
A method where a network device determines the receiving and sending start times to calculate a time deviation, which is then used to send indication information to a terminal device to determine the correct uplink transmission time, ensuring synchronization and preventing transmission failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the NR system deploys uplink on 3.5 GHz frequency band, then downlink coverage is improved, but uplink coverage becomes limited due to asynchronous transmission
Solution Approach 1:
The network device performs preliminary timing alignment by determining the timing difference between downlink and uplink transmissions, then sends indication information to the terminal device in advance. This allows the terminal device to pre-adjust its uplink transmission timing based on the timing difference, ensuring synchronized transmission before actual data exchange occurs.
2Adaptability or versatility
If downlink and uplink transmissions are asynchronous, then frequency band sharing between NR and LTE is enabled, but terminal devices cannot determine correct uplink subframe numbers
Solution Approach 1:
The network device acts as an intermediary by introducing indication information that carries timing difference data. This intermediary mechanism bridges the asynchronous downlink and uplink transmissions, allowing the terminal device to calculate correct uplink subframe numbers by combining the indication information with received downlink subframe numbers, thus preserving subframe number information despite asynchronous operation.
3Adaptability or versatility
If different gNBs have different time deviations, then flexible timing configuration is achieved, but cross-cell interference increases due to lack of synchronization
Solution Approach 1:
Each gNB independently determines its own timing difference between downlink and uplink transmissions, allowing local optimization of timing configuration. The terminal device applies the timing adjustment locally based on indication information from its serving gNB, enabling each cell to operate with optimized timing while maintaining overall system coordination and reducing cross-cell interference.
Data Source
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Figure 4-b~5-a
AI summary
Embodiments of this application disclose an information sending method, an information receiving method, a network device, and a terminal device, to enable the terminal device to determine a correct uplink transmission time, thereby avoiding an uplink transmission failure. The embodiments of this application provide an information sending method, including: determining, by a network device, a first receiving start time and a first sending start time, where the first receiving start time is a receiving time at which the network device starts to receive a signal in a first time period, and the first sending start time is a sending time at which the network device starts to send a signal in a second time period; and sending, by the network device, indication information to a terminal device, where the indication information is used to instruct the terminal device to determine a second sending start time, and the second sending start time is determined based on the first receiving start time and the first sending start time.