Extended Cyclic Shift Reference Signal Generation for LTE Orthogonality
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Solution Overview
Problem
Current wireless communication systems, such as LTE, face limitations in extending channel estimation reference signals to support multiple antennas and new multi-user MIMO and CoMP technologies, requiring an increase in the number of orthogonal resources while maintaining backward compatibility with existing LTE systems.
Innovation Solution
The method involves determining an extended cyclic shift (CS) by combining a basic CS parameter and an extended CS parameter, allowing for the generation and transmission of a reference signal with increased CS values, such as from 8 to 12 or 16, to enhance orthogonal resource multiplexing and reduce interference between SRS sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of cyclic shift values is increased to support more orthogonal resources for multiple antennas and multi-user MIMO, then the system capacity and orthogonality are improved, but the complexity of signal generation and processing increases
Solution Approach 1:
The cyclic shift value generation is segmented into two independent parts: a base cyclic shift value determined by higher layer signaling, and an additional cyclic shift value determined by physical layer parameters (subframe index, slot index, symbol index). This segmentation allows the system to support multiple orthogonal resources without requiring complex centralized generation, as each part can be independently calculated and combined.
Solution Approach 2:
The additional cyclic shift value is made dynamic by incorporating time-varying parameters (subframe index, slot index, symbol index) into its calculation. This dynamic approach allows the system to automatically generate different cyclic shift values across time resources, increasing orthogonality and system capacity without requiring manual configuration or complex static tables.
2Reliability
If extended cyclic shift values are used to increase orthogonal resources, then interference between SRS sequences is reduced, but the signaling overhead and system complexity increase
Solution Approach 1:
The system enables user equipment to self-generate the additional cyclic shift value using publicly available parameters (subframe index, slot index, symbol index, cell ID) without requiring explicit signaling from the network. This self-service mechanism maintains high orthogonality while minimizing signaling overhead, as each device independently computes its cyclic shift components.
Solution Approach 2:
The base cyclic shift value serves multiple functions: it provides the fundamental cyclic shift for SRS transmission and acts as a configurable parameter that can be adjusted by higher layer signaling to accommodate different system configurations. This multi-functionality reduces the need for separate signaling mechanisms for different cyclic shift scenarios.
3Measurement precision
If the reference signal sequence is extended to support more antennas and advanced technologies, then the channel estimation capability is improved, but the processing complexity and computational load increase
Solution Approach 1:
The system improves channel estimation capability by changing the cyclic shift parameter rather than extending the fundamental sequence length. By applying different cyclic shift values (base + additional) to the same base sequence, the system creates orthogonal variations that enable multi-antenna and multi-user support without increasing the underlying sequence complexity or computational burden.
Data Source
AI summary
The present specification relates to a method/apparatus for extending and transmitting a reference signal, and to a method and apparatus for transmitting a cyclic shift (hereinafter, referred to as CS) parameter. In generating the extended reference signal, the CS is determined as a function for both a basic CS parameter and an extended CS parameter.