Configurable TDD Interface for Distributed Antenna Systems
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Solution Overview
Problem
Existing TDD systems face challenges in synchronizing communication directions between devices, leading to signal loss and interference, especially in environments like buildings, and require additional hardware like combiners for simplex devices, increasing costs and complexity.
Innovation Solution
A distributed antenna system (DAS) that uses a main hub and remote antenna units to manage TDD RF signals, allowing for simultaneous simplex and duplex operations without the need for additional combiners, by configuring RF interfaces to switch between downlink and uplink directions using control signals and band-pass filters, and utilizing frequency division multiplexing for signal distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receivers are used to provide precise time reference for synchronizing TDD communication directions, then synchronization accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The system uses self-contained voltage-controlled oscillators (VCOs) in each device to generate local clock signals for TDD switching, eliminating the need for external GPS receivers. Each device independently maintains synchronization through its own frequency synthesizer locked to a reference frequency, providing autonomous time-division duplex operation without additional synchronization hardware.
2Adaptability or versatility
If combiners are placed between simplex devices and the hub to enable TDD connection, then connectivity is improved, but system cost and complexity increase
Solution Approach 1:
The hub incorporates a universal TDD interface that can directly connect to both duplex and simplex devices through configurable RF interfaces. The system uses a single TDD-capable interface design that adapts to different device types, eliminating the need for separate combiner hardware for simplex devices while maintaining full TDD functionality.
3Ease of operation
If separate downlink and uplink interfaces are used for simplex devices, then signal direction control is improved, but device complexity and cost increase
Solution Approach 1:
The system employs dynamic switching of a single RF interface between downlink and uplink modes using voltage-controlled oscillators and time-division multiplexing. Instead of maintaining separate static interfaces, the interface dynamically reconfigures its function based on the current communication direction, reducing hardware complexity while maintaining precise signal direction control through software-timed switching.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances wireless coverage and reduces costs and complexity by enabling seamless switching between communication directions and supporting both simplex and duplex modes with a single hub, eliminating the need for separate hardware and simplifying network configuration.
Implementation Method 1
a first band-pass filter of the plurality of band-pass filters separates a respective one of the downlink RF signals and the uplink RF signals
Implementation Method 2
a respective downlink IF/RF circuit of the plurality of downlink IF/RF circuits receives the combined downlink IF signal and produces respective downlink RF signals for respective RF bands A and B
Data Source
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AI summary
A communications unit (102) of a communication system having a first interface (116A, 116B) operable as a simplex interface or a duplex interface. The first interface (116A, 116B) is configured to receive first downlink radio frequency signals from a first interface (103A, 103B) of an upstream device (101A, 101B), wherein the first interface (116A, 116B) of the communications unit (102) is configured to be coupled to the downlink path of the communication system and the uplink path of the communication system. The unit also includes a second interface (117A, 117B) which is operable only as a simplex interface. The second interface (117A, 117B) is configured to be coupled to the uplink signal path of the communication system. The unit (102) is configured to transmit first uplink radio frequency signals to the first interface (103A, 103B) of an upstream device (101A, 101B) using the first interface (116A, 116B) when the first interface (116A, 116B) is operable as a duplex interface. The unit is configured to transmit uplink radio frequency signals to a second interface (105A) of an upstream device (101A, 101B) with the second interface (117A, 117B) when the first interface (116A, 116B) is operable as a simplex interface.