CAZAC Reference Signal Structure for Uplink Control Reliability
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Solution Overview
Problem
Current wireless cellular communication systems face challenges in ensuring reliable transmission of uplink control information, particularly ACK/NACK signals, due to their susceptibility to errors and the need for timely and accurate Hybrid Automatic Repeat Request (HARQ) operations, which existing reference signal structures do not adequately address.
Innovation Solution
The proposed solution involves a reference signal structure that uses a combination of CAZAC and near-CAZAC sequences, allowing for the allocation of multiple tone blocks and bands, enabling backwards compatibility with legacy systems while supporting bandwidth aggregation, thereby enhancing channel estimation and demodulation reliability across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reference signal sequence is used for multiple tone blocks, then device complexity is reduced, but channel estimation accuracy deteriorates
Solution Approach 1:
The reference signal is segmented into multiple sequences, with each sequence assigned to a specific tone block. This allows each tone block to have its own dedicated reference signal sequence, enabling independent channel estimation for each block while maintaining manageable complexity through systematic allocation.
Solution Approach 2:
Different reference signal sequences are assigned to different tone blocks based on their specific characteristics and requirements. This local differentiation ensures that each tone block receives the most appropriate reference signal for its channel conditions, improving overall channel estimation accuracy without requiring a completely unique sequence for each block.
2Measurement precision
If multiple reference signal sequences are used for different tone blocks, then channel estimation accuracy is improved, but device complexity increases
Solution Approach 1:
A set of reference signal sequences is designed to serve multiple purposes: they can be used across different tone blocks, and the same sequence can potentially be reused in different contexts. This multi-functionality allows the system to achieve accurate channel estimation through sequence differentiation while avoiding the need for entirely unique sequences for each tone block, thereby managing complexity.
3Adaptability or versatility
If reference signals are transmitted across multiple frequency bands, then system adaptability is improved, but signal reliability deteriorates
Solution Approach 1:
The frequency spectrum is segmented into multiple bands, with each band receiving a dedicated reference signal sequence. This segmentation allows the system to operate across multiple frequency bands simultaneously while maintaining distinct reference signals for each band, ensuring that reliability mechanisms can be applied independently to each band's transmission.
Solution Approach 2:
The reference signal sequences are designed with specific parameters that can be adjusted or selected based on the operating band. By changing or selecting appropriate sequence parameters for different frequency bands, the system can adapt to varying channel conditions while maintaining reliable transmission of uplink control information across all supported bands.
Data Source
AI summary
A method for transmitting a plurality of sequences across a plurality of bands of a wireless spectrum is described in which a first sequence is produced using a set of reference signal sequences, wherein the set of reference signal sequences comprises at least CAZAC sequences and near-CAZAC sequences. A second sequence is also produced. The first sequence is transmitted in a first band of the wireless spectrum, and the second sequence is transmitted in a second band of the wireless spectrum. The first and the second sequences are transmitted concurrently by a same user equipment.