WLAN PPDU Padding for Multi-User OFDM Symbol Alignment
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Solution Overview
Problem
Next-generation wireless local area network (WLAN) systems require a method to transmit physical layer convergence procedure (PLCP) protocol data units (PPDUs) efficiently to multiple users with varying data sizes, necessitating a solution to ensure all PPDUs have the same bit size for consistent transmission over the same number of OFDM symbols.
Innovation Solution
A method and apparatus for generating data blocks with padding bits appended to each data unit, where the number of padding bits is determined by the number of OFDM symbols, data bits per symbol, and service data unit length, ensuring all data units have the same length for multi-user transmission in a WLAN system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If data units with varying data sizes are transmitted to multiple users, then the transmission can accommodate different user data requirements, but the PPDUs will have different bit sizes requiring different numbers of OFDM symbols
Solution Approach 1:
The patent applies preliminary action by determining the maximum data size requirement among all users before transmission, and pre-calculating the number of OFDM symbols needed. This allows the system to prepare a unified PPDU structure in advance that can accommodate all users' data requirements, avoiding the complexity of handling variable-length PPDUs during transmission.
Solution Approach 2:
The patent changes the parameter of OFDM symbol count from a variable determined per user to a unified parameter determined by the maximum data size. By adjusting the number of OFDM symbols based on the maximum requirement and applying padding to shorter data units, the system transforms a complex variable-structure problem into a simpler fixed-structure problem that maintains adaptability.
2Productivity
If padding bits are appended to all data units to ensure equal bit sizes, then the transmission complexity is reduced and throughput is improved, but additional overhead is introduced
Solution Approach 1:
The patent applies partial action by appending padding bits only to the extent necessary to reach the minimum PPDU size required by the user with the maximum data size. Rather than padding all users to an excessively large size, the system calculates the precise padding needed for each user, minimizing overhead while ensuring all PPDUs have equal bit sizes for efficient transmission.
3Stability of the object's composition
If the number of OFDM symbols is determined by the maximum data size among all users, then all PPDUs can be transmitted with the same number of symbols, but users with smaller data sizes will experience increased transmission time
Solution Approach 1:
The patent resolves this contradiction by performing preliminary calculations to determine the maximum data size requirement among all users before transmission. This advance determination allows the system to set a fixed number of OFDM symbols that accommodates all users, and pre-apply padding to shorter data units. As a result, all users experience uniform transmission timing without unnecessary delays, because the padding is optimally calculated based on actual maximum requirements rather than arbitrary over-provisioning.
Data Source
AI summary
A method and device for receiving a data block in a wireless communication system, the method performed by a receiver. The method includes: receiving a physical layer protocol data unit (PPDU) from a transmitter over an operating channel, the PPDU including a signal field, a Very High Throughput-Signal-A (VHT-SIG-A) field, a Very High Throughput-Signal-B (VHT-SIG-B) field and a padded data block, generating a first data block by removing zero or more physical padding bits from the padded data block in a physical layer; and generating a second data block by removing zero or more Medium Access Control (MAC) padding bits from the first data block in a MAC layer.