Cyclic Shift Delay for 16-Chain WLAN Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Next-generation wireless local area network (WLAN) systems face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and require efficient transmission methods to prevent unintended beamforming across up to 16 transmit chains.
Innovation Solution
A method for transmitting a Physical Protocol Data Unit (PPDU) in a WLAN system by applying a Cyclic Shift Delay (CSD) value to each transmit chain in the Extreme High Throughput (EHT) field, minimizing the difference in reception powers between the VHT-STF, HE-STF, or EHT-STF and data fields, ensuring efficient transmission and backward compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If CSD values are not applied to each transmit chain in the EHT field, then beamforming gain is improved, but unintended beamforming occurs causing reception power imbalance between STF and data fields
Solution Approach 1:
The patent applies different CSD values to different transmit chains (Tx0-Tx15) based on their specific spatial positions and beamforming requirements. Each transmit chain receives a locally optimized CSD value from the lookup table, allowing precise control of phase and amplitude characteristics for each chain while maintaining overall beamforming performance and preventing unintended beamforming effects.
2Productivity
If the number of transmit chains is increased to 16 for higher throughput, then area throughput is improved, but device complexity and CSD value determination becomes more difficult
Solution Approach 1:
The patent pre-calculates and stores optimal CSD values for all 16 transmit chains in a lookup table during system initialization or manufacturing. This preliminary action eliminates the need for real-time complex calculations when transmitting PPDU, allowing the system to handle 16 transmit chains efficiently with simple table lookups, thus supporting high area throughput without excessive operational complexity.
Solution Approach 2:
The patent extends the CSD value parameter set from traditional 8 transmit chains to 16 transmit chains by providing specific CSD values for Tx0 through Tx15 in the lookup table. This parameter extension allows the system to accommodate higher throughput requirements with more transmit chains while maintaining manageable complexity through standardized parameter definitions.
3Productivity
If CSD values are optimized for EHT field only, then spectrum efficiency in next-generation WLAN is improved, but backward compatibility with legacy systems deteriorates
Solution Approach 1:
The patent segments the PPDU structure into distinct fields (VHT-STF, HE-STF, EHT-STF, data fields) and applies CSD values specifically to the EHT field portion while maintaining separate handling for legacy fields. This segmentation allows optimization of spectrum efficiency for next-generation WLAN in the EHT field without interfering with legacy system operation in earlier fields, thus maintaining backward compatibility.
Data Source
AI summary
A method and an apparatus for transmitting a PPDU in a WLAN system are proposed. Specifically, a transmitter generates a PPDU and transmits the PPDU to a receiver. The PPDU includes a legacy field and an EHT field. The legacy field includes a VHT-STF and a HE-STF. The EHT field includes an EHT-STF and a data field. The EHT field is configured on the basis of a CSD value of each transport chain. The CSD value is determined as a candidate CSD value in which the sum of a first absolute value and a second absolute value is the minimum on the basis of a power ratio. The power ratio is a ratio of a received power of the VHT-STF, the HE-STF, or the EHT-STF to a received power of the data field. The first absolute value is an absolute value of a value related to 5 percent of a CDF relative to the power ratio. The second absolute value is an absolute value of a value related to 95 percent of the CDF relative to the power ratio.