OFDM Data Tone Mapping onto Guard Tones
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Solution Overview
Problem
In wireless personal area networks using multi-band OFDM systems, data tones near the edges of the frequency band are prone to adjacent channel interference and attenuation due to low-order filters, leading to reduced signal-to-noise ratios and communication efficiency.
Innovation Solution
Mapping data tones onto guard tones at the edges of the orthogonal frequency division multiplex symbol, duplicating data tones to create copies that are placed on guard bins, thereby boosting the signal-to-noise ratio and reducing the impact of filter attenuation and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If low-order filters are used in multi-band OFDM systems, then device complexity and cost are reduced, but signal-to-noise ratio and communication reliability deteriorate due to filter attenuation and adjacent channel interference
Solution Approach 1:
The patent copies data tones from frequency bands with good signal conditions to guard tones in frequency bands suffering from filter attenuation and adjacent channel interference. This copying mechanism provides redundant signal paths, allowing the receiver to combine signals from multiple paths and maintain communication reliability even when using simplified low-order filters.
2Productivity
If data tones are placed near the edges of the frequency band, then data transmission capacity is increased, but signal-to-noise ratio deteriorates due to adjacent channel interference and filter attenuation
Solution Approach 1:
Data tones at frequency band edges are copied to guard tone positions. The receiver combines the original edge data tones with their copies, effectively increasing the signal-to-noise ratio for these critical high-capacity transmission positions while maintaining the overall data transmission rate.
Solution Approach 2:
The patent creates a composite signal structure by combining original data tones with copied tones in the frequency domain. This composite approach allows the system to exploit frequency diversity, where signals from different frequency positions (original and copied) are combined to achieve both high data transmission capacity and improved signal-to-noise ratio.
3Reliability
If guard tones are used for their traditional purpose of providing frequency separation, then adjacent channel interference is reduced, but data transmission capacity is decreased due to unused frequency resources
Solution Approach 1:
The patent makes guard tones multi-functional: they continue to provide frequency separation and interference protection between adjacent channels, while simultaneously serving as additional carriers for data transmission through the copying mechanism. This dual functionality eliminates the traditional trade-off between interference protection and data capacity.
Solution Approach 2:
By copying data tones to guard tone positions, the patent transforms guard tones from passive interference barriers into active data carriers. The copied signals on guard tones provide redundant information that can be combined at the receiver, effectively increasing data transmission capacity while maintaining the guard tones' traditional interference protection function.
Data Source
AI summary
A device (104, 106, 108) is provided for wireless communication. The device (104, 106, 108) includes a transmitter (200) operable to transmit an orthogonal frequency division multiplex symbol. The orthogonal frequency division multiplex symbol has a first set of copied tones adjacent a first end of the orthogonal frequency division multiplex symbol, a second set of copied tones adjacent a second end of the orthogonal frequency division multiplex symbol, and a plurality of data tones provided between the first and second sets of copied tones. The first and second sets of copied tones include copies of at least some of the plurality of data tones.