OFDM Symbol Padding and Encoder Bit Distribution
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently transmitting data due to constraints related to integer number of bits per orthogonal frequency division multiplexing (OFDM) symbols, leading to exclusions of desirable modulation and coding schemes (MCS) that result in non-smooth data rate adaptation and high data throughput limitations.
Innovation Solution
The method involves adding padding bits to ensure that information bits fill an integer number of OFDM symbols, allowing for unequal bit distribution among encoders and different encoding techniques for the last block in a data unit, thereby accommodating system configurations that previously violated integer constraints, and using a virtual number of coded bits per symbol to satisfy these conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If padding bits are added to ensure integer number of OFDM symbols, then data rate adaptation smoothness improves, but transmission overhead increases
Solution Approach 1:
The patent changes the parameter of bit distribution by introducing unequal bit distribution among encoders, where different encoders receive different numbers of information bits. This allows the system to accommodate various MCS configurations without requiring excessive padding bits, thus maintaining smooth data rate adaptation while reducing transmission overhead.
Solution Approach 2:
The patent implements dynamic bit allocation that adapts to different transmission conditions and MCS configurations. The system dynamically determines the number of information bits for each encoder based on the total number of bits available and the number of encoders, allowing flexible adaptation to various data rates without fixed padding requirements.
2Reliability
If integer constraints on OFDM symbols are enforced, then system reliability improves, but MCS selection flexibility deteriorates
Solution Approach 1:
The patent segments the information bits into different groups for different encoders, with the last encoder receiving a different number of bits than previous encoders. This segmentation allows the system to satisfy integer constraints on OFDM symbols while accommodating various MCS configurations, thereby maintaining both reliability and flexibility.
Solution Approach 2:
The patent introduces asymmetry in bit distribution among encoders, where the last encoder receives a different number of information bits compared to other encoders. This asymmetric distribution enables the system to meet integer constraints while supporting a broader range of MCS selections, resolving the contradiction between reliability and flexibility.
3Device complexity
If equal bit distribution among encoders is used, then encoding simplicity improves, but system throughput deteriorates
Solution Approach 1:
The patent changes the bit distribution parameter from equal to unequal distribution among encoders. By allocating different numbers of information bits to different encoders based on system conditions, the system achieves higher throughput while maintaining manageable encoding complexity through standardized encoding processes.
Data Source
AI summary
In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, a plurality of information bits to be included in the PHY data unit is received. A number of padding bits that need to be added to the information bits such that the information bits, after having been encoded, fill an integer number of orthogonal frequency division multiplexing (OFDM) symbols is determined. The number of padding bits is added to the information bits prior to encoding and the information bits are parsed to a number of encoders. The information bits are encoded to generate coded data bits. A last block of the data unit is encoded differently from the previous blocks. The PHY data unit to include the coded data bits is generated.