OFDM Symbol Calculation for Excluded MCS in WLAN
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Solution Overview
Problem
Current wireless local area network (WLAN) standards, such as IEEE 802.11ac, exclude certain modulation and coding schemes (MCSs) for specific transmission configurations, leading to unacceptably long packets due to padding bits, which limits data rate utilization and efficiency.
Innovation Solution
Implementing altered encoding techniques to accommodate excluded MCSs by calculating the number of OFDM symbols using alternative equations, such as Nsym,init = i*mSTBC*⌈8L+16i*mSTBCNDBPS⌉, to ensure integer data bits per symbol, allowing for the use of excluded MCSs in transmission configurations where they were previously prohibited.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If excluded MCSs are used for transmission, then data rate increases, but packet length becomes unacceptably long due to padding bits
Solution Approach 1:
The patent changes the parameter calculation method by introducing alternative equations (Equations 2 and 3) that compute a different initial number of OFDM symbols (Nsym,init) compared to the standard Equation 1. This parameter change allows excluded MCSs to be used while controlling packet length by adjusting how Nsym,init is calculated based on whether the MCS is excluded or not
Solution Approach 2:
The patent segments the MCS usage into two distinct paths: one for allowed MCSs (using standard Equation 1) and one for excluded MCSs (using alternative Equations 2 or 3). This segmentation allows different calculation methods to be applied based on the MCS type, enabling excluded MCSs to be utilized without causing unacceptably long packets
2Length of moving object
If excluded MCSs are prohibited, then packet length is controlled, but data rate utilization is limited
Solution Approach 1:
The patent introduces dynamic selection of calculation equations based on the MCS type. The system dynamically chooses between Equation 1 (for allowed MCSs) and Equations 2 or 3 (for excluded MCSs), allowing flexible adaptation to different transmission scenarios and enabling data rate utilization improvement without sacrificing packet length control
3Reliability
If standard encoding techniques are used, then protocol compliance is maintained, but excluded MCSs cannot be utilized
Solution Approach 1:
The patent introduces an intermediary mechanism - the modified Equation 2 or 3 calculation for Nsym,init - that bridges between standard protocol compliance and extended MCS utilization. This intermediary allows the system to maintain compatibility with standard decoding flows while enabling the use of excluded MCSs through a intermediate calculation step
Data Source
AI summary
A physical layer (PHY) data unit is generated for transmission via a communication channel in accordance with a transmission configuration. The transmission configuration corresponds to at least one of (i) one or more particular numbers of spatial streams, and (ii) one or more particular channel bandwidths. A number of orthogonal frequency division multiplexing (OFDM) symbols to be included in a payload of the PHY data unit is determined based on (i) determining the number of OFDM symbols according to a first technique when using a modulation and coding scheme (MCS) from a set of MCSs allowed for the transmission configuration, and (ii) determining the number of OFDM symbols according to a second technique when using an MCS excluded from the set of MCSs allowed for the transmission configuration.