Sounding Reference Signal Multiplexing in Uplink Channels
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently multiplexing uplink sounding resource signals (SRS) with acknowledgement (ACK) and channel quality indication (CQI) channels, leading to suboptimal performance and resource utilization.
Innovation Solution
The method involves modifying the channel structure by replacing existing symbols with SRS in a slot of a sub-frame, determining the length and type of time domain orthogonal spreading codes based on SRS presence, and applying these codes to facilitate multiplexing of SRS with ACK and CQI channels, allowing for efficient resource allocation and improved channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SRS is transmitted as a separate physical channel, then channel estimation accuracy is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent merges the SRS channel with the PUCCH structure by allowing SRS to replace existing symbols (ACK or CQI symbols) within the PUCCH resource block. This combining approach enables SRS transmission to share the same time-frequency resources as ACK/CQI channels, thereby improving resource utilization efficiency while maintaining channel estimation functionality through the integrated structure.
Solution Approach 2:
The patent creates a multi-functional PUCCH structure that can dynamically serve multiple purposes: transmitting ACK/CQI information when SRS is not needed, and transmitting SRS for channel estimation when required. The flexible symbol replacement mechanism allows the same physical channel structure to adapt to different transmission needs, achieving both efficient resource utilization and accurate channel estimation across varying conditions.
2Productivity
If SRS replaces existing symbols in PUCCH, then resource utilization is improved, but multiplexing capacity may deteriorate
Solution Approach 1:
The patent implements a dynamic symbol replacement mechanism where the PUCCH structure adapts based on SRS transmission requirements. When SRS needs to be transmitted, specific symbols (ACK or CQI symbols) are dynamically replaced by SRS symbols within the same resource block. This dynamic reconfiguration allows the system to optimize resource utilization for SRS transmission while maintaining the ability to restore original multiplexing capacity when SRS transmission is not required.
3Object-affected harmful factors
If orthogonal spreading codes are applied to SRS, then interference reduction is improved, but device complexity deteriorates
Solution Approach 1:
The patent applies orthogonal spreading codes to SRS symbols, transforming the SRS transmission by multiplying with orthogonal codes (such as Walsh-Hadamard codes). This parameter change in the signal domain enables effective interference reduction between multiple users transmitting SRS simultaneously. The orthogonal codes provide natural interference suppression through their mathematical properties, reducing the need for complex interference cancellation algorithms at the receiver.
Data Source
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AI summary
A resource block can include all symbols in a slot for each, generally a multiple of 12, sub-carrier in the resource block. A slot is typically 0.5 milliseconds (ms) and includes 7 symbols for short cyclic prefix (CP) and 6 symbols for long CP. The resource block can include a SRS channel as well as other channels such as an acknowledgement (ACK) channel and a channel quality indication (CQI) channel. Although defined as a separate physical channel, the SRS can be multiplex with uplink channels. In accordance therewith, an SRS can be detected in a slot of a 1.0 ms sub-frame constituting two slots, typically one slot but not the other including the SRS. The structure of the slot can be modified to facilitate the multiplexing by, e.g., replacing an existing symbol with the SRS, and a length and a type of a time domain orthogonal spreading code can be determined for each slot as a function of SRS presence.