Distributed Antenna Sub-band Extraction via Frequency Transform
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Solution Overview
Problem
Distributed antenna systems (DAS) currently route entire downlink signals, including frequency bands with no voice or data, which is inefficient and wasteful, as they do not distinguish between sub-bands with and without data transmission.
Innovation Solution
The method involves performing a frequency transform on downlink signals to identify and extract sub-bands containing data for transmission, using algorithms like fast Fourier transform, discrete Fourier transform, or discrete cosine transform, and routing only these sub-bands through the DAS, thereby reducing bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the entire downlink signal is routed to remote antenna units, then all frequency bands are transmitted, but bandwidth is wasted on frequency bands with no data transmission
Solution Approach 1:
The downlink signal is divided into multiple frequency sub-bands using Fast Fourier Transform (FFT). Each sub-band is independently analyzed to determine whether it contains data transmission. Only sub-bands with data are routed to remote antenna units, while empty sub-bands are discarded. This segmentation enables selective transmission, reducing bandwidth waste on empty frequency bands.
Solution Approach 2:
The system extracts only the necessary sub-bands containing data from the complete downlink signal. By identifying and removing empty sub-bands before transmission, the system eliminates unnecessary bandwidth consumption while maintaining all essential data-carrying frequency components.
2Productivity
If frequency transform and sub-band extraction are implemented, then bandwidth efficiency improves, but processing complexity increases
Solution Approach 1:
The system performs Fast Fourier Transform and sub-band analysis in advance, before the signal is routed to remote antenna units. This preliminary processing identifies which sub-bands contain data, allowing the system to prepare an optimized transmission plan that reduces subsequent processing requirements at remote units.
Solution Approach 2:
The master unit creates a frequency domain representation (copy) of the downlink signal through FFT processing. This frequency domain copy is analyzed to identify data-containing sub-bands, avoiding the need to process the entire time-domain signal at each remote antenna unit, thus reducing overall computational complexity.
3Loss of energy
If only data-containing sub-bands are routed, then bandwidth usage is optimized, but signal reconstruction complexity increases
Solution Approach 1:
The master unit acts as an intermediary that performs the complex frequency transform and sub-band selection operations. By centralizing the FFT processing and sub-band extraction at the master unit, the system avoids distributing complex processing tasks to multiple remote antenna units, simplifying their functionality while maintaining bandwidth optimization benefits.
Data Source
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AI summary
Embodiments are disclosed for extracting sub-bands of interest from signals in a frequency domain for transmission via a distributed antenna system. In one aspect, a transformed downlink signal is generated by performing a frequency transform on a downlink signal. The transformed downlink signal represents the downlink signal in a frequency domain. At least one sub-band of the transformed downlink signal is identified as including data to be transmitted via the distributed antenna system. The sub-band is extracted from the transformed downlink signal for transmission via the distributed antenna system.