Extended Sequence Modulation for OFDM Out-of-Band Leakage
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Solution Overview
Problem
In orthogonal frequency division multiplexing (OFDM) systems, non-orthogonal sub-carriers between adjacent transmission frequency bands cause out-of-band leakage, leading to interference and degraded transmission performance due to different frequency spacing configurations or frequency offsets.
Innovation Solution
Implementing an extended sequence modulation data sending rule, where data is multiplied by extended elements with a phase difference of π, and sent on sub-carriers with specific spacing relationships, to cancel side lobe amplitudes and reduce interference between adjacent frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is transmitted on adjacent transmission frequency bands with different frequency spacing configurations or frequency offsets, then spectrum efficiency is improved by utilizing multiple sub-carriers, but out-of-band leakage occurs causing interference between adjacent frequency bands
Solution Approach 1:
The patent applies preliminary anti-action by performing extended sequence modulation on the data before transmission. This modulation technique pre-cancels the out-of-band leakage by extending the sequence length and applying specific weighting, so that when the signal is transmitted, the side lobes are already suppressed. This prevents interference to adjacent frequency bands before the interference can occur, resolving the contradiction between maintaining high spectrum efficiency and preventing out-of-band leakage.
2Object-generated harmful factors
If extended sequence modulation is applied to suppress out-of-band leakage, then interference between adjacent frequency bands is reduced, but device complexity increases due to additional processing steps
Solution Approach 1:
The patent changes the parameter of sequence length from the standard length to an extended length (e.g., from 64 to 128 samples). This parameter change enables the modulation to suppress out-of-band leakage more effectively by creating a longer transition region where side lobes can be cancelled. The increased sequence length provides better spectral containment while the processing remains based on standard FFT algorithms, making the complexity increase manageable.
Data Source
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AI summary
Disclosed are a data sending and receiving method, apparatus, and device, and a computer readable storage medium. The method includes: when a first transmission frequency band sends data by adopting an extended sequence modulation data sending rule, data to be transmitted on spaced sub-carriers of the first transmission frequency band is respectively multiplied by each extended element in an extended sequence with a length of 2K to obtain extended data with a number of 2K, where there is another extended element with a phase difference of π relative to each extended element in the extended sequence; and the extended data with the number of 2K is sent on 2K spaced sub-carriers of the first transmission frequency band, where K is a positive integer.