Cyclic Shift Diversity Sequences for High-Stream MIMO AGC Accuracy
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Solution Overview
Problem
Existing MIMO communication systems face challenges in improving system capacity and spectral efficiency, particularly with high communication requirements, and suffer from automatic gain control (AGC) gain setting errors due to correlations between spatial streams.
Innovation Solution
A cyclic shift diversity sequence-based method is employed to generate physical layer protocol data units (PPDUs) with STF, LTF, and data fields determined by a cyclic shift diversity (CSD) sequence, expanding the maximum number of spatial streams to 16 or more, reducing correlations between STFs, and minimizing AGC gain setting errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum number of spatial streams is expanded to 16 or more, then system capacity and spectral efficiency are improved, but device complexity increases due to requirements on number of antennas
Solution Approach 1:
The patent changes the parameter of cyclic shift values in the CSD sequence to enable support for 16 or more spatial streams. By defining specific cyclic shift values for different spatial stream indices, the system can handle increased numbers of streams without proportionally increasing hardware complexity, as the same antenna infrastructure can be utilized with modified signal processing parameters.
2Productivity
If the maximum number of spatial streams is expanded to 16 or more, then system capacity and spectral efficiency are improved, but implementation complexity increases
Solution Approach 1:
The patent modifies the CSD sequence parameters to support expanded spatial streams. The cyclic shift values are specifically designed to maintain signal orthogonality and reduce interference across 16 or more streams, enabling high spectral efficiency while keeping implementation complexity manageable through mathematical optimization rather than hardware proliferation.
Solution Approach 2:
The patent transitions from spatial domain multiplexing alone to a combination of spatial and temporal domain processing by introducing cyclic shifts in the time domain. This dimensional approach allows the system to differentiate and process multiple spatial streams through time-based signal variations, effectively increasing capacity without linearly increasing the number of physical antennas or processing channels.
3Measurement precision
If cyclic shift diversity is applied to reduce correlation between STFs on spatial streams, then AGC gain setting error is reduced, but processing complexity increases
Solution Approach 1:
The patent applies cyclic shift diversity by changing the phase parameters of STF signals across different spatial streams. This parameter modification reduces correlation between simultaneous transmissions, leading to more accurate power measurements and reduced AGC gain setting errors. The processing complexity increase is mitigated by using straightforward phase rotation operations that can be efficiently implemented in existing signal processing chains.
Data Source
AI summary
The embodiments of this application provides a cyclic shift diversity sequence-based communication method. In the method, a first communication apparatus generates a physical layer protocol data unit (PPDU) and sends the PPDU to a second communication apparatus. The PPDU includes a short training field (STF), a long training field (LTF), and a data field that are determined based on a cyclic shift diversity (CSD) sequence. After receiving the PPDU from the first communication apparatus, the second communication apparatus performs processing based on the PPDU. The CSD sequence includes L elements. L is a maximum number of spatial streams supported by the first communication apparatus and the second communication apparatus. The maximum number of spatial streams is greater than or equal to 16.