Downlink OFDMA Padding and Packet Extension Grouping
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Solution Overview
Problem
Current methods for downlink OFDMA multiuser transmission in 802.11ax lack a concrete method for determining padding and packet extension parameters, leading to increased implementation complexity and system overhead, particularly in ensuring all stations receive data simultaneously and efficiently.
Innovation Solution
The proposed solution involves grouping users into two groups based on their FEC encoding, with the first group having FEC encoded bits spanning all OFDM symbols and the second group having them span only a part, allowing for optimized padding and packet extension parameters to be determined based on the user with the longest encoded packet duration, reducing power consumption by avoiding processing of unnecessary OFDM symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If padding and packet extension are applied to ensure all STAs receive data simultaneously in downlink OFDMA, then transmission synchronization is improved, but system overhead increases
Solution Approach 1:
The patent segments STAs into two groups based on their FEC encoding characteristics: Group 1 where FEC encoded bits span all OFDM symbols, and Group 2 where FEC encoded bits span only a part of OFDM symbols. This segmentation allows different padding and packet extension parameters to be applied to each group, achieving transmission synchronization while minimizing system overhead by avoiding unnecessary padding for STAs that don't require it.
2Reliability
If packet extension is increased to give receivers enough time to process the last OFDM symbol, then processing completeness is improved, but transmission efficiency deteriorates
Solution Approach 1:
The patent applies different packet extension durations to different STA groups based on their local characteristics. Group 1 STAs receive full packet extension to ensure complete processing, while Group 2 STAs receive reduced or no packet extension since their FEC encoded bits don't span all OFDM symbols. This local quality approach ensures processing completeness where needed while maintaining transmission efficiency by avoiding unnecessary delays.
3Ease of manufacture
If uniform padding parameters are applied to all STAs, then implementation simplicity is maintained, but power consumption increases due to processing of unnecessary OFDM symbols
Solution Approach 1:
The patent introduces dynamic padding parameter allocation based on STA group membership and FEC encoding characteristics. Instead of static uniform padding, the system dynamically determines appropriate padding parameters for each STA group, allowing STAs to process only the necessary number of OFDM symbols. This reduces power consumption while maintaining implementation feasibility through standardized group-based parameter determination.
Data Source
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AI summary
An transmission apparatus of the present disclosure comprises a transmission signal generator which, in operation, generates a transmission signal that includes a legacy preamble, a nonlegacy preamble, a data field and a packet extension field, wherein the non-legacy preamble comprises a first signal field and a second signal field, the second signal field comprising a common field that carries RU assignment information for one or more terminal stations and a user-specific field that carries per-user allocation information for the one or more terminal stations, wherein the one or more terminal stations are grouped into a single group or two group, and wherein in case that the one or more terminal stations are grouped into a first group and a second group, the first group comprises at least one terminal station that has FEC encoded bits spanned over all of the OFDM symbols in the data field while the second group comprises one or more terminal stations that have FEC encoded bits spanned over only a part of the OFDM symbols in the data field; and a transmitter which, in operation, transmits the generated transmission signal.