OFDMA 2-Symbol Interval Windowing for Adjacent Band Interference Reduction
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Solution Overview
Problem
In communication systems using OFDMA, existing windowing techniques such as 1-symbol and 3-symbol interval windowing schemes face challenges in maintaining spectral efficiency while reducing interference with adjacent bands, leading to degraded Error Vector Magnitude (EVM) performance and increased hardware complexity.
Innovation Solution
A method and apparatus for performing a 2-symbol interval windowing process, where the current symbol is windowed by overlapping signals from both the previous and current symbol intervals, using a symbol buffer and windowing processor to transmit a windowed signal without introducing processing delays, thus improving spectral efficiency and reducing EVM degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time windowing is used to reduce interference with adjacent bands, then interference reduction is achieved, but spectral efficiency is degraded
Solution Approach 1:
The patent applies different windowing coefficients to different time intervals within the symbol. Specifically, a first windowing coefficient is applied during the guard interval period while a second windowing coefficient is applied during the data symbol period. This local differentiation allows interference reduction during the guard interval without degrading the spectral efficiency of the data transmission portion.
2Object-affected harmful factors
If 1-symbol interval windowing is used, then interference reduction is achieved, but Error Vector Magnitude performance is degraded
Solution Approach 1:
The patent segments the symbol into two distinct intervals: the guard interval and the data symbol period. Different windowing coefficients are applied to each segment. The first windowing coefficient during the guard interval reduces interference, while the second windowing coefficient during the data period maintains signal quality and EVM performance.
3Object-affected harmful factors
If 3-symbol interval windowing is used, then interference reduction is achieved, but hardware complexity is increased
Solution Approach 1:
The patent extracts and applies windowing coefficients specifically during the guard interval period rather than across multiple symbols. This extraction of the windowing operation to a specific time interval reduces the computational burden and hardware complexity compared to multi-symbol windowing schemes while maintaining interference reduction benefits.
Data Source
AI summary
A method and apparatus for processing time windowing to transmit a signal in a Broadband Wireless Access (BWA) communication system based on Orthogonal Frequency Division Multiple Access (OFDMA). A signal of a first interval included in a previous symbol prior to a current symbol is stored as a signal of a previous symbol interval. The current symbol includes a guard interval and an effective symbol interval subsequent to the guard interval. The current symbol is windowed by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol. A windowed signal is transmitted.