OFDM Signal Extension Padding for Integer Bit Alignment
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Solution Overview
Problem
In orthogonal frequency-division multiplexing (OFDM) wireless data transmission systems, particularly in IEEE 802.11 standards, the longer data symbol duration leads to increased processing complexity at the receiver, and current padding schemes struggle with non-integer calculations for padding bits, making it difficult to implement certain modulation and coding schemes effectively.
Innovation Solution
A special padding rule is applied to OFDM symbols, ensuring the number of information bits for the last symbol is an integer by adding padding bits and distributing them unevenly or evenly across encoders, using dynamic puncturing, and adjusting coding parameters to maintain integer values for both coded and information bits, thereby facilitating efficient encoding and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of information bits for the last OFDM symbol is calculated based on standard padding rules, then the padding scheme works for most cases, but it results in non-integer values for certain MCS and SE combinations, making implementation difficult or impossible
Solution Approach 1:
The patent changes the parameter calculation method by introducing a special padding rule that modifies how the number of information bits is calculated for the last OFDM symbol. Instead of using the standard formula that can produce non-integer values, the patent applies a ceiling function to ensure the result is always an integer, thereby resolving the contradiction between adaptability to different MCS schemes and ease of implementation.
2Productivity
If a 4×OFDM symbol duration is used to improve data efficiency, then data transmission efficiency is improved, but processing complexity at the receiver increases
Solution Approach 1:
The patent applies preliminary action by adding signal extension (SE) to the OFDM symbol structure in advance. This SE provides additional processing time at the receiver before the next data symbol arrives, allowing the receiver to process the longer 4× symbol duration more effectively. The SE is prepared and integrated into the symbol structure beforehand, enabling the receiver to utilize this extended time for complex processing operations.
3Reliability
If signal extension of multiples of 4 μs is added to provide additional processing time, then receiver processing capability is improved, but the symbol structure becomes more complex
Solution Approach 1:
The patent introduces asymmetry by adding signal extension only to specific OFDM symbols (particularly the last symbol) rather than uniformly to all symbols. This asymmetric approach provides the necessary processing time advantage to the receiver where it is most needed, while avoiding the unnecessary complexity that would result from adding SE to every symbol. The selective application of SE creates an asymmetric symbol structure that optimizes the balance between processing capability and structural complexity.
Data Source
AI summary
Systems, apparatuses and methods described herein provide a method for padding a signal extension of orthogonal frequency-division multiplexing (OFDM) symbols. A transceiver may obtain a plurality of data symbols for transmission, and determine that a number of information bits for a last symbol of the plurality of data symbols is not an integer value. A special padding rule may be applied to add padding bits to the last symbol. A number of coded bits for the last symbol may be determined when the number of information bits for the last symbol has changed, and the plurality of data symbols for data transmission may be encoded based on the determined number of coded bits for the last symbol.