Terminal Frequency Synchronization in NR-LTE Coexistence
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Solution Overview
Problem
In the context of 5G NR-LTE co-existence, terminals face challenges in implementing frequency synchronization with LTE uplink carriers, leading to potential network coverage issues and inefficient resource utilization due to high signal attenuation at high frequency bands.
Innovation Solution
A synchronization method where a terminal receives a synchronization signal on a second downlink carrier, presynchronized with the LTE uplink carrier, allowing for frequency synchronization and enhancing network coverage and resource utilization by using LTE uplink carriers for NR uplink transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the 5G NR operates only on high frequency band, then peak rate and system capacity are improved, but network coverage deteriorates due to serious signal attenuation
Solution Approach 1:
The patent segments the frequency spectrum into two parts: high frequency band for achieving high peak rate and system capacity, and licensed spectrum (4G LTE band) for ensuring network coverage. The terminal can switch between these segments based on coverage requirements, thus resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent introduces a new dimension of frequency spectrum utilization by allowing 5G NR to access not only high frequency bands but also licensed spectrum through NR-LTE co-existence. This multi-dimensional frequency usage enables the system to simultaneously achieve high data rates and wide coverage.
2Reliability
If the 5G NR shares the licensed spectrum with 4G LTE, then network coverage and resource utilization are improved, but frequency synchronization becomes complex
Solution Approach 1:
The patent uses the downlink carrier as an intermediary to achieve frequency synchronization for uplink transmission. The network device sends downlink carrier frequency information to the terminal, which then uses this information to synchronize its uplink transmission frequency, simplifying the synchronization process while enabling NR-LTE co-existence.
Solution Approach 2:
The patent implements a feedback mechanism where the network device provides downlink carrier frequency information to the terminal, and the terminal uses this feedback to adjust its uplink transmission frequency. This closed-loop feedback system simplifies frequency synchronization in NR-LTE co-existence scenarios.
3Measurement precision
If the terminal uses NR downlink carrier for frequency synchronization, then frequency synchronization accuracy is improved, but uplink transmission on LTE carrier becomes unsynchronized
Solution Approach 1:
The patent uses downlink carrier frequency information as an intermediary to bridge the synchronization gap between NR and LTE systems. The terminal receives downlink carrier frequency information from the network device and uses this intermediary information to synchronize its uplink transmission frequency, ensuring both accuracy and stability.
Solution Approach 2:
The patent changes the frequency parameter of the uplink transmission based on the received downlink carrier frequency information. By adjusting the uplink frequency parameter according to the downlink carrier, the terminal maintains accurate frequency synchronization while preserving uplink-downlink pairing stability.
Data Source
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AI summary
A synchronization method and an apparatus are provided. The method includes: receiving, by a terminal, a system message on a first downlink carrier, where the system message includes first indication information and second indication information, the first indication information indicates a frequency domain range of a first uplink carrier, the second indication information indicates a frequency domain range of a second downlink carrier, and a frequency of the first uplink carrier is presynchronized with a frequency of the second downlink carrier; and receiving, by the terminal, a synchronization signal on the second downlink carrier, to implement frequency synchronization with the first uplink carrier. According to the synchronization method in this application, in NR-LTE co-existence, a terminal can implement frequency synchronization with an LTE uplink carrier, so that the terminal can perform uplink transmission by using a frequency domain resource in the LTE uplink carrier, thereby enhancing a coverage capability of an NR network and improving resource utilization of an LTE licensed spectrum.