Distributed Antenna System Delay Measurement Using Gaussian Pulse Timing
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Solution Overview
Problem
Distributed Antenna Systems (DAS) face challenges in accurately measuring downlink and uplink delays due to the complexity of signal propagation across different domains, particularly between digital inputs and analog RF outputs, and RF inputs to digital outputs, which affects communication services.
Innovation Solution
A system and methodology are introduced that utilize a digital host communicatively coupled with an antenna unit via a communication medium, employing a Gaussian pulse to measure delays. The system includes a digital waveform generator, a spectrum analyzer, and a digital to RF converter, allowing for accurate determination of downlink, uplink, and round-trip propagation delays by converting digital signals to RF signals and analyzing them using a spectrum analyzer, regardless of channel changes or modulation types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RF signal propagation through distributed antenna system is measured using conventional methods, then basic delay information can be obtained, but measurement precision is insufficient due to signal distortion across digital-analog domains
Solution Approach 1:
The patent introduces a timing reference signal as an intermediary element that mediates between the digital baseband domain and analog RF domain. This reference signal travels through the same transmission medium as the data signal, allowing synchronization and delay measurement without direct comparison between distorted digital and analog waveforms. The intermediary reference signal enables precise delay measurement by providing a common reference point that both transmitter and receiver can use for timing correlation.
Solution Approach 2:
The patent changes the measurement parameter from direct RF signal correlation to timing reference signal correlation. By measuring the delay of a dedicated timing reference signal rather than attempting to measure data signal delays directly, the system achieves higher precision. The timing reference signal is designed with specific characteristics (known pattern, adequate power level) that make it suitable for accurate timing measurement, transforming the measurement problem into a more solvable parameter space.
2Adaptability or versatility
If multiple remote antenna units are connected to base station, then signal coverage is improved, but delay variation across different units increases
Solution Approach 1:
The patent segments the delay measurement and compensation process into per-antenna-unit operations. Each remote antenna unit independently measures its own delay relative to the base station using the timing reference signal, and each unit's delay information is independently compensated. This segmentation allows the system to handle multiple antenna units with different propagation characteristics without requiring complex inter-unit coordination, maintaining delay consistency across all units while preserving expanded signal coverage.
Solution Approach 2:
The patent implements a feedback mechanism where delay measurements from each remote antenna unit are reported back to the base station, and compensation values are adjusted based on these measurements. The base station sends timing reference signals, receives delayed versions at each antenna unit, measures the actual delays, and uses this feedback information to compensate for delay variations. This closed-loop feedback ensures delay consistency across multiple antenna units while allowing the system to maintain expanded geographic coverage.
3Measurement precision
If timing reference signal is transmitted at every frame interval, then delay measurement accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic transmission of timing reference signals at optimized intervals rather than continuous transmission. The reference signals are sent at specific frame intervals sufficient to maintain accurate delay measurements for mobile devices, but spaced out to minimize unnecessary energy consumption. This periodic action balances measurement accuracy requirements with energy efficiency, transmitting reference signals only when needed for synchronization and delay measurement rather than continuously.
Data Source
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AI summary
A waveform generator comprising circuitry configured to generate a digital representation of a waveform and apply the digital representation of the waveform to a digital interface of a radio system configured to propagate the waveform and convert the digital representation of the waveform to a radio frequency signal transmitted at the antenna; and mark the digital representation of the waveform with respect to a frame of digital data with a marker. Measurement of when the waveform occurs in the radio frequency signal based on the marker occurs by a spectrum analyzer. Determination occurs of a downlink propagation delay for the radio system between application of the digital representation of the waveform at the digital interface and transmission of the radio frequency signal at the antenna. The shape of the waveform allows for accurate delay measurement.