Antenna Sharing for Asynchronous TDD Radios

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Solution Overview

Problem

Asynchronous time-division duplex (TDD) radios face challenges in antenna sharing due to the need for significant isolation between transmit and receive modes, as existing systems struggle to effectively reduce interference from co-located transmitters to receivers, requiring roughly 110 dB of isolation to maintain proper receiver operation.

Innovation Solution

The proposed solution involves pre-selecting resonant frequencies for each antenna, mechanically combining multiple antennas to form a single physical antenna, and using a control switch module with circulators and band-pass filters to isolate and filter out undesired frequencies, ensuring that only desired signals are received while transmitters are active, and vice versa.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple TDD radios are co-located and share an antenna, then antenna utilization is improved, but transmit interference to receivers increases

Engineering Contradiction:

Improveantenna sharing capabilityVSAvoidtransmit interference to receivers

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The frequency band is segmented into multiple sub-bands, with each antenna element tuned to a specific sub-band. This frequency segmentation allows multiple radios to share the antenna while minimizing interference through frequency division, as each antenna primarily handles a specific frequency range.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each antenna element is designed with specific resonant frequencies and impedance characteristics tailored to its designated sub-band. This local optimization of antenna properties ensures that each antenna element is most effective at its assigned frequency range, reducing cross-interference between different radio channels.

Inventive Principle:

Principle #3Local quality

2Device complexity

If asynchronous TDD radios share an antenna, then system complexity is reduced, but isolation requirements increase to 110 dB

Engineering Contradiction:

Improvesynchronization system complexityVSAvoidreceiver operation reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A hybrid coupling network is introduced as an intermediary between the antenna elements and the radio frequency circuits. This network provides automatic isolation control, dynamically adjusting the coupling between antenna elements based on the operational state of each radio, thereby achieving the required 110 dB isolation without complex synchronization mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically changes the impedance and coupling parameters of the hybrid network based on the transmit/receive state of each radio. During transmit modes, the network adjusts to provide maximum isolation; during receive modes, it optimizes for signal reception, thereby maintaining receiver reliability without requiring strict asynchronous synchronization.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If frequency bands are allocated for TV channels, then broadcast coverage is improved, but available bandwidth for other uses is reduced

Engineering Contradiction:

Improvefrequency band coverageVSAvoidavailable bandwidth

Core Design Contradiction:

Area of stationary objectVSQuantity of substance

Solution Approach 1:

The antenna system is designed to handle multiple frequency bands and multiple radio functions simultaneously. By implementing a reconfigurable antenna array with hybrid coupling, the same physical antenna structure serves both TV broadcast reception and other communication functions, maximizing the utilization of the allocated frequency spectrum.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach reduces interference by attenuating undesired signals through a combination of antenna separation, insertion loss, and filter rejection, effectively minimizing signal strength from co-located transmitters to protect receiver sensitivity.

Implementation Method 1

The antenna is coupled to a circulator having a first port, a second port and a third port

Methodology Applied

Scientific EffectCirculator:

Implementation Method 2

The second port of the circulator is coupled to a band-pass filter

Methodology Applied

Scientific EffectBand-pass filter: Filter (electronic)

Implementation Method 3

three resonant frequencies f1, f2 and f3 are pre-selected for antenna 220

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9337531B2Method and system for antenna sharing

Publication Date: 2016.05.10 6HARMONICS

AI summary

The present disclosure provides a method and a system for antenna sharing for asynchronous TDD radios comprising an integrated antenna with plurality of antennas and a circuit to limit the co-located transmitters signals, a plurality of transmitters, each transmitter operable on a predetermined set of channels and coupled via a respective transmit switch to a combiner and in turn to an antenna, a plurality of receivers, each receivers operable on a predetermined set of channels and coupled via a respective receive switch to a splitter and in turn to an antenna and a switch controller connected to respective transmit and receive switches for asynchronously connecting at least one transmitter and at least one receiver to the antenna for effecting antenna sharing.