Bandwidth-Adaptive DMRS Sequences for Cross-Band MU-MIMO
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Solution Overview
Problem
In LTE-A and NR systems, terminal devices with varying capabilities face challenges in configuring orthogonal or quasi-orthogonal downlink demodulation reference signals (DMRS) for multi-user multiple-input multiple-output (MU-MIMO) scenarios, particularly when devices operate on different bandwidths or bandwidth parts, leading to inefficient data demodulation.
Innovation Solution
A method for determining reference signal sequences based on parameters of first and second bandwidths, ensuring the sequences are the same, orthogonal, or quasi-orthogonal, by using offset values in the frequency domain start positions and subcarrier spacing to support MU-MIMO between terminal devices operating on different bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reference signal sequences are generated based on maximum bandwidth for all terminal devices, then sequence generation is simplified, but terminal devices operating on different bandwidths cannot achieve orthogonal or quasi-orthogonal DMRS configurations for MU-MIMO
Solution Approach 1:
The patent applies local quality by making the reference signal sequence generation adaptive to local bandwidth conditions. Instead of using a uniform maximum bandwidth for all terminal devices, the system generates reference signal sequences based on the actual bandwidth of each terminal device. This is achieved by introducing a bandwidth indicator that specifies whether to use maximum bandwidth or actual bandwidth for sequence generation, allowing each terminal device to have sequences optimized for its specific operating conditions while maintaining orthogonality for MU-MIMO operations.
2Adaptability or versatility
If terminal devices use different bandwidths for operation, then device capability flexibility is improved, but reference signal orthogonality for MU-MIMO cannot be ensured
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference signal sequence generation parameters based on terminal device bandwidth capabilities. The system introduces a bandwidth indicator parameter that can take different values (e.g., 0 for maximum bandwidth, 1 for actual bandwidth) to control the sequence generation process. This allows terminal devices operating on different bandwidths to generate reference signal sequences that maintain orthogonality relationships, ensuring reliable MU-MIMO operations while supporting diverse device capabilities.
3Device complexity
If a single reference signal sequence generation method is used for all bandwidths, then system complexity is reduced, but data demodulation accuracy deteriorates for terminal devices on different bandwidths
Solution Approach 1:
The patent applies dynamics by making the reference signal sequence generation method adaptable and dynamic rather than static and uniform. The system dynamically selects between maximum bandwidth-based and actual bandwidth-based sequence generation methods based on the bandwidth indicator. This dynamic approach allows terminal devices to use the most appropriate sequence generation method for their specific operating conditions, improving data demodulation accuracy while maintaining reasonable system complexity through standardized control mechanisms.
Data Source
AI summary
A method for determining a reference signal sequence, a terminal device, and a network device, the including receiving, by a terminal device, first indication information sent by a network device, determining, by the terminal device, a target resource based on the first indication information, determining, by the terminal device, a reference signal sequence based on parameters of a first bandwidth and parameters of a second bandwidth, and sending or receiving, by the terminal device, the reference signal sequence on the target resource.