DMRS Sequence Diversity for LTE User Capacity
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Solution Overview
Problem
The existing LTE communication system is limited in supporting a large number of users in the competitive data transmission area due to the restricted number of orthogonal DMRS sequences, leading to decreased detection performance and increased interference during retransmissions.
Innovation Solution
The introduction of multiple RS sequences based on different root sequences allows for a greater number of users to transmit data simultaneously, with each terminal device using a unique RS sequence for initial transmission and potentially a different sequence for retransmission to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple users transmit data simultaneously in the competitive data transmission area using the same DMRS sequence, then the system can support more user connections, but the detection performance decreases severely due to inability to distinguish channels
Solution Approach 1:
The patent segments the DMRS sequences by introducing multiple root sequences (first root sequence and second root sequence) to divide the previously unified sequence space. This segmentation allows different terminal devices to use different root sequences, enabling the base station to distinguish between multiple users while supporting simultaneous data transmission in the competitive transmission area.
2Device complexity
If only eight shifts are used in the Zadoff-Chu sequence to ensure orthogonality, then the sequence structure remains simple, but the system can only support a maximum of eight users in the same time interval
Solution Approach 1:
The patent transitions from a one-dimensional solution (eight cyclic shifts within a single root sequence) to a two-dimensional solution (multiple root sequences with multiple cyclic shifts each). By introducing the dimension of multiple root sequences, the system can support up to 16 users simultaneously while maintaining manageable sequence structure complexity.
3Device complexity
If the same DMRS sequence is used by multiple terminal devices in the competitive transmission area, then resource allocation remains simple, but the base station cannot correctly obtain channels of the two terminal devices
Solution Approach 1:
The patent applies local quality by assigning different root sequences to different terminal devices based on their specific transmission needs. Each terminal device locally selects an appropriate root sequence (first or second) based on its transmission characteristics, allowing the base station to perform accurate channel estimation for each device while maintaining simple overall resource allocation.
Data Source
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AI summary
Embodiments of the present invention provide a data transmission method, a terminal device, and a base station. The data transmission method includes: determining, by a terminal device, a first reference signal (RS) sequence corresponding to a first time interval, where the first RS sequence is one of N RS sequences, N is a positive integer greater than 1, and the N RS sequences are generated based on at least two root sequences; sending, by the terminal device, the first RS sequence to a base station in the first time interval; determining, by the terminal device from the N RS sequences according to the first RS sequence, one RS sequence as a second RS sequence corresponding to a second time interval, where the second RS sequence is determined according to the first RS sequence; and sending, by the terminal device, the second RS sequence to the base station in the second time interval.