Resource Block Multicarrier Modulation for Spectral Agility
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Solution Overview
Problem
Current wireless communication systems face challenges with large inter-carrier interference and excessive out-of-band emission due to large sidelobes of rectangular pulses in OFDM, particularly in systems with dynamic channel access and non-contiguous spectrum usage, which limits their effectiveness in spectral agile systems.
Innovation Solution
The implementation of a resource block-based multicarrier modulation (RB-MCM) transmitter and receiver structure that partitions the spectrum into multiple resource blocks, applies baseband MCM or single carrier modulation schemes, and uses frequency shift for spectral leakage reduction, enabling low out-of-band emission and robustness to frequency and timing asynchrony.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM with rectangular pulse is used, then spectral efficiency is improved, but out-of-band emission increases
Solution Approach 1:
The patent segments the spectrum into multiple resource blocks (RBs) and applies independent filtering to each RB. This segmentation allows the system to maintain high spectral efficiency within each RB while suppressing out-of-band emissions at the RB boundaries through localized filtering operations.
Solution Approach 2:
The patent applies different filtering characteristics to different parts of the spectrum (each RB). By making the filter design local to each RB rather than global across the entire bandwidth, the system can optimize for low OOBE at RB edges while maintaining spectral efficiency within RBs.
2Reliability
If OFDM with long cyclic prefix is used, then multipath channel robustness is improved, but latency increases
Solution Approach 1:
The patent divides the bandwidth into multiple RBs, each processed independently with shorter cyclic prefixes. This segmentation allows the system to achieve multipath robustness on a per-RB basis with reduced CP length, thereby lowering overall latency while maintaining reliability.
3Adaptability or versatility
If OFDM is used in non-contiguous spectrum, then spectrum utilization is improved, but inter-carrier interference increases
Solution Approach 1:
The patent segments the non-contiguous spectrum into multiple RBs and applies independent FFT/IFFT operations to each segment. This segmentation isolates the ICI within each RB while allowing efficient utilization of non-contiguous spectrum resources across different RBs.
Solution Approach 2:
The patent applies localized filtering and processing to each RB independently. This local processing approach maintains signal integrity within each RB while enabling flexible allocation across non-contiguous spectrum, thereby reducing ICI without sacrificing spectrum utilization.
4Device complexity
If rectangular pulse filtering is used, then implementation complexity is reduced, but sidelobes increase
Solution Approach 1:
The patent segments the filtering operation into multiple smaller RB-level filters rather than one large global filter. This segmentation reduces the complexity of each individual filter while collectively achieving superior sidelobe suppression through the combined effect of multiple localized filters.
Data Source
AI summary
A resource block (RB)-based multicarrier modulation (MCM) transmitter and receiver structure for spectral agile systems are disclosed. The transmitter and the receiver are capable of sharing opportunistically available and non-contiguous channels with other users. The RB-MCM partitions the available spectrum, contiguous or non-contiguous, into multiple RBs (same or different sizes), applies a baseband MCM or single carrier modulation, or coded single carrier or multicarrier schemes in each RB with a type of spectral leakage reduction technique, and applies RB modulation for each RB to modulate the signal from baseband to the frequency band of that RB. At the receiver, the received signal may be filtered and RB demodulation may be applied to put each RB signal in baseband and a baseband multicarrier or single carrier or coded single carrier or coded multicarrier demodulation may be applied to each RB signal. Different RBs may use different modulation schemes.