Information transmission method and information transmission device
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Solution Overview
Problem
In 5G vehicle-to-everything (V2X) communications, ensuring device-to-device direct communication without changing the symbol boundary position is challenging due to the need for larger subcarrier spacing, which shortens the cyclic prefix, leading to issues like intersymbol interference, frequency synchronization, and potential time synchronization problems.
Innovation Solution
The solution involves using a special cyclic prefix longer than the common prefix in the first symbol, ensuring the length of the first time unit is an integer multiple of the common symbol length, and incorporating guard periods and sequences to maintain symbol boundary consistency and resolve synchronization issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If larger subcarrier spacing is used to support higher-frequency carrier and larger bandwidth in 5G, then the bandwidth and frequency support are improved, but the cyclic prefix length is shortened which causes intersymbol interference and synchronization problems
Solution Approach 1:
The first time unit is segmented into multiple second time units, where the first symbol uses a special cyclic prefix and subsequent symbols use common cyclic prefixes. This segmentation allows the system to maintain symbol boundary consistency while supporting larger bandwidth through increased subcarrier spacing.
Solution Approach 2:
The first symbol in the first time unit is assigned a special cyclic prefix with longer duration, while other symbols use standard common cyclic prefixes. This local differentiation ensures that the critical first symbol maintains synchronization accuracy, preventing intersymbol interference while allowing other symbols to use efficient standard lengths.
2Productivity
If the cyclic prefix length is shortened due to larger subcarrier spacing, then the system bandwidth efficiency is improved, but symbol boundary consistency and time synchronization are compromised
Solution Approach 1:
The first symbol is prepared with a special cyclic prefix before data transmission begins. This preliminary action ensures that the initial symbol boundary is established with high precision, enabling accurate time synchronization and preventing intersymbol interference that would otherwise result from the shortened cyclic prefix lengths in 5G.
3Length of moving object
If device-to-device direct communication is implemented with extended coverage distance, then the communication range is improved, but the symbol decoding accuracy deteriorates due to timing offset and synchronization issues
Solution Approach 1:
The special cyclic prefix in the first symbol acts as an intermediary that bridges the gap between extended coverage distance requirements and symbol decoding accuracy. By providing a longer reference sequence at the beginning of each time unit, it enables accurate timing offset estimation and synchronization even when devices are at the edge of the extended coverage area.
Data Source
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AI summary
This application provides an information transmission method and an information transmission apparatus. The method includes: mapping, by a first terminal device, first information to a first time unit and a second time unit; and sending, by the first terminal device, the first information in the first time unit and the second time unit, where the first time unit includes a first symbol including a first cyclic prefix, the second time unit includes at least one second symbol including a second cyclic prefix, a length of the first cyclic prefix is greater than a length of the second cyclic prefix, and a length of the first time unit is equal to N times a length of the second symbol including the second cyclic prefix in the second time unit. According to the information transmission method and the information transmission apparatus in the embodiments of this application, a boundary position of a symbol used to decode data is not changed while device-to-device data transmission is ensured.