LTE Data Transmission Latency Reduction via Symbol-Level TTI
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Solution Overview
Problem
In LTE systems, the long data transmission latency due to the long time taken by base stations to decode and respond to uplink data packets, leading to increased retransmission delays, affects user experience.
Innovation Solution
A data transmission method where a network device receives and demodulates reference signals and physical channels from terminal devices, optimizing their placement and configuration within a slot to reduce the transmission time interval (TTI) to three or four symbols, allowing for more frequent scheduling and reducing latency without increasing reference signal overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each data packet is sent in one subframe with traditional LTE structure, then the base station has sufficient time to decode the data packet, but the data transmission latency becomes relatively long
Solution Approach 1:
The patent segments the transmission time by dividing the subframe into slots and further into symbols. By reducing the TTI to the symbol level (3 or 4 symbols), the transmission time is segmented into smaller units, allowing faster scheduling and reducing latency while maintaining decoding accuracy through adequate reference signal resources.
Solution Approach 2:
The patent changes the TTI parameter from traditional subframe level (1ms) to symbol level (3-4 symbols). This parameter change enables much shorter transmission intervals, increasing scheduling frequency and reducing latency while the reference signal configuration ensures decoding accuracy is maintained.
2Loss of time
If the TTI is reduced to three or four symbols, then the data transmission latency is reduced and scheduling frequency is increased, but the reference signal overhead may increase
Solution Approach 1:
The patent makes the reference signal serve multiple functions: it is used for both channel estimation and demodulation of the physical channel. This multi-functionality allows the reference signal to be more efficient, reducing the overhead required while supporting the shortened TTI structure.
Solution Approach 2:
The patent uses a partial action approach by configuring reference signals only in the necessary symbols (i-th symbol for demodulation, and optionally (i+1)-th symbol for channel estimation) rather than throughout the entire TTI. This selective placement reduces reference signal overhead while maintaining the benefits of shortened TTI.
3Reliability
If reception of the data packet is incorrect, then retransmission is required, but the minimum time interval between retransmission and initial transmission becomes relatively long
Solution Approach 1:
The patent prepares the system for potential retransmission by establishing a short minimum time interval between initial transmission and retransmission through the reduced TTI structure. This preliminary setup allows the system to quickly respond to reception errors, reducing the penalty time for retransmission while maintaining reception accuracy through proper reference signal configuration.
Data Source
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AI summary
Embodiments of the present invention provide a data transmission method, a network device, and a terminal. The data transmission method includes: receiving, by a network device, a first reference signal and a first physical channel that are sent by a first terminal device, where the first reference signal is at the ith symbol in a slot, i is a positive integer less than 7, the first physical channel occupies n symbols in the slot, and n is 1, 2, or 3; and demodulating, by the network device, the first physical channel according to the first reference signal. According to the present invention, a data transmission latency can be reduced.