DAS Node Unit Multiplexer Time-Division Signal Processing
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Solution Overview
Problem
In distributed antenna systems (DAS), the conventional method of arithmetically summing uplink signals from multiple remote units can lead to digital overflow, increasing complexity and requiring additional auto level control, which complicates the system.
Innovation Solution
A node unit in the DAS processes and outputs uplink signals as a single signal without arithmetic summation, using a multiplexer to selectively output one of the uplink signals at a predetermined interval and a down-sampler to convert the sampling rate to match any one of the uplink signals, along with optional filtering to eliminate image signals or perform average filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uplink signals from multiple remote units are arithmetically summed, then a single transmission signal is generated, but digital overflow occurs and system complexity increases
Solution Approach 1:
The patent segments the uplink signal processing by dividing multiple uplink signals into different time slots using a multiplexer, rather than arithmetically summing them simultaneously. This temporal segmentation prevents digital overflow while maintaining single-signal transmission capability.
Solution Approach 2:
The patent employs periodic action through time-division multiplexing, where uplink signals from different remote units are transmitted in alternating time slots. The multiplexer selectively outputs signals at predetermined intervals, creating a periodic transmission pattern that avoids signal summation overflow.
2Reliability
If a multiplexer and down-sampler are used to process uplink signals without arithmetic summation, then digital overflow is prevented, but signal processing steps increase
Solution Approach 1:
The patent introduces a multiplexer as an intermediary device that mediates between multiple uplink signals and the transmission channel. Instead of arithmetically summing signals, the multiplexer selectively passes individual signals through at different time slots, with a down-sampler converting the sampling rate to match the original signal rate.
3Adaptability or versatility
If uplink signals are transmitted through one channel from multiple remote units, then system connectivity is maintained, but digital overflow occurs due to signal magnitude increase
Solution Approach 1:
The patent applies dynamics by making the signal transmission path time-variable through the multiplexer. The multiplexer dynamically switches between different uplink signal sources at predetermined time intervals, allowing multiple remote units to share one channel without simultaneous signal summation that causes overflow.
Data Source
AI summary
The inventive concept relates to a distributed antenna system (DAS), and more particularly, to an uplink signal transmission operation of each of node units constituting a DAS. A node unit of a DAS includes a multiplexer configured to generate a single uplink signal by selectively outputting any one of m uplink signals received from m lower node units at an interval of a predetermined output time, where m is a positive integer greater than 1, and a down-sampler configured to output a transmission uplink signal by converting a sampling rate of the single uplink signal to correspond to a sampling rate of any one of the m uplink signals. Accordingly, it is possible to provide a DAS capable of processing and outputting, as one signal, uplink signals received from a plurality of remote units, without any error.