OFDM Bandwidth Allocation via Subcarrier Alignment
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Solution Overview
Problem
In wireless cellular networks, the proliferation of electromagnetic emissions leads to congested spectral bands, causing signal degradation and interference due to the presence of unwanted signals, which reduces communication capacity and data throughput in OFDM and OFDMA systems.
Innovation Solution
The proposed solution involves allocating spectral bandwidth by choosing a common subcarrier spacing for orthogonal subcarriers, eliminating guard subcarriers, and aligning subcarriers across multiple channels to reduce inter-carrier interference and increase spectral efficiency, allowing for efficient use of the allocated spectrum without wasting bandwidth on unnecessary guard subcarriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard subcarriers are assigned at both ends of the nominal channel bandwidth, then inter-carrier interference is reduced, but spectral efficiency deteriorates due to wasted bandwidth
Solution Approach 1:
The patent extracts and eliminates the guard subcarriers from the OFDMA system. By removing these unnecessary subcarriers that were previously assigned at both ends of the nominal channel bandwidth, the system achieves full utilization of the allocated spectrum while maintaining orthogonality through proper subcarrier spacing selection, thereby resolving the contradiction between interference reduction and spectral efficiency
Solution Approach 2:
The patent changes the parameter of subcarrier spacing to a common value that enables efficient bandwidth allocation. By selecting an appropriate subcarrier spacing parameter, the system can eliminate guard subcarriers while maintaining orthogonality and reducing inter-carrier interference, thus improving spectral efficiency without sacrificing reliability
2Productivity
If multiple different nominal channels are allocated sequentially, then channel capacity increases, but inter-carrier interference increases due to boundary effects
Solution Approach 1:
The patent merges multiple different nominal channels into a unified frequency allocation structure. By aligning subcarriers across channel boundaries and using a common subcarrier spacing, the system eliminates the harmful boundary effects that cause inter-carrier interference, allowing multiple channels to operate simultaneously with full spectral efficiency
Solution Approach 2:
The patent establishes equipotentiality in terms of subcarrier alignment across different nominal channels. By ensuring that subcarriers are aligned and spaced uniformly across all channels, the system creates a harmonious frequency structure where adjacent channels do not interfere with each other, enabling high channel capacity without reliability loss
Data Source
AI summary
Techniques for bandwidth allocation in communication systems such as OFDM, OFDMA, or SC-FDMA systems to improve spectral efficiency and increase flexibility and adaptability with scalable single or multiple-carrier bandwidth allocation characteristics.