OFDM Symbol Subcarrier Mapping for WLAN Bandwidth Adaptation
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Solution Overview
Problem
Current wireless local area network (WLAN) standards face challenges in efficiently communicating device capabilities and data throughput across different communication protocols, particularly in transitioning between short-range high-throughput and long-range low-data rate applications, due to limitations in channel bandwidth and data rate compatibility.
Innovation Solution
The method involves generating OFDM symbols with encoded information bits mapped to constellation symbols, distributed across multiple data subcarriers, using tone duplication and insertion techniques to accommodate varying channel bandwidths, and employing modulation schemes like BPSK, while maintaining consistent bit allocation for signal fields across different bandwidths, ensuring compatibility and efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If OFDM symbols are generated with bandwidth expansion techniques (tone duplication and insertion) to accommodate wider channel bandwidths, then adaptability across different WLAN protocols is improved, but device complexity increases
Solution Approach 1:
The OFDM symbol is segmented into multiple portions (first portion and second portion) with different subcarrier allocations. The first plurality of data subcarriers and second plurality of data subcarriers are treated as separate segments that can be independently configured, allowing flexible adaptation to different bandwidth requirements while maintaining manageable processing complexity for each segment
Solution Approach 2:
The patent extends the bandwidth dimension by using tone duplication and insertion techniques. Constellation symbols are mapped to additional subcarriers beyond the original information bit bandwidth, effectively expanding the frequency dimension to accommodate wider channel bandwidths (e.g., 80 MHz, 160 MHz) while maintaining compatibility with narrower bandwidth protocols
2Productivity
If more data subcarriers are allocated to accommodate wider bandwidths, then data throughput is improved, but signal processing complexity increases
Solution Approach 1:
Constellation symbols are copied and mapped to multiple data subcarriers. The same set of constellation symbols derived from encoded information bits is mapped to both the first plurality of data subcarriers and the second plurality of data subcarriers, effectively duplicating the signal across wider bandwidth to increase throughput without requiring additional unique signal processing for each subcarrier
Solution Approach 2:
The OFDM symbol structure is designed to serve multiple functions across different bandwidth scenarios. The same basic structure with encoded bits, constellation mapping, and subcarrier allocation can universally accommodate various WLAN protocols (802.11a/n/ac) by adjusting the number of subcarriers and applying tone duplication/insertion, rather than requiring protocol-specific signal processing paths
Data Source
AI summary
In a method of generating an orthogonal frequency division multiplexing (OFDM) symbol, a plurality of information bits is encoded to generate a plurality of coded bits. The plurality of information bits corresponds to a first bandwidth, while the OFDM symbol includes a number of data tones corresponding to a second bandwidth. The coded bits are mapped to a plurality constellation symbols. The constellation symbols are mapped to a first plurality of data subcarriers corresponding to a first portion of the OFDM symbol and to a second plurality of data subcarriers corresponding to a second portion of the OFDM symbol. A subset of data subcarriers in the first plurality of data subcarriers and in the second plurality of data subcarriers are set to one or more predetermined values. The OFDM symbol is then generated to include at least the first plurality of data subcarriers and the second plurality of data subcarriers.