Signal Path Isolation Circuit for Neutral-Host Hardware
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Neutral-host wireless communication systems face challenges in achieving sufficient signal isolation between transmit and receive paths, especially in time-domain duplex (TDD) communication bands, due to the lack of synchronization between multiple mobile network operators (MNOs), leading to interference and desensitization of receive paths by high-power transmit signals from adjacent subchannels.
Innovation Solution
The implementation of a precancellation circuit with a phase shifter and reflection tuner in the transmit path, coupled with a directional coupler in the receive path, which generates a cancellation reference signal that destructively interferes with the transmit signal leakage, providing enhanced isolation beyond the standard Adjacent Channel Leakage Ratio (ACLR) of 45 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MNOs share neutral-host hardware for TDD communication, then hardware utilization efficiency is improved, but signal isolation between transmit and receive paths deteriorates due to lack of synchronization
Solution Approach 1:
The patent applies preliminary anti-action by generating a cancellation reference signal that is the complex conjugate of the expected transmit leakage signal, and introducing it into the receive path before the harmful leakage interferes with the desired receive signal. This preemptive cancellation approach counteracts the isolation problem that would otherwise occur due to unsynchronized TDD switching between multiple MNOs sharing neutral-host hardware.
2Object-affected harmful factors
If power amplifiers are deactivated for isolation, then transmit signal leakage is reduced, but this approach cannot be applied when multiple MNOs share hardware with unsynchronized switching points
Solution Approach 1:
The patent introduces an intermediary cancellation reference signal that mediates between the transmit path and receive path. Instead of requiring direct coordination between multiple MNOs' power amplifiers, the cancellation signal acts as an intermediate element that can be generated and injected to achieve isolation. This allows the system to maintain adaptability for multiple MNOs while still reducing transmit signal leakage.
3Device complexity
If standard ACLR isolation of 45 dB is used, then device complexity is kept manageable, but signal reception quality deteriorates in the presence of high-power transmit signals from adjacent subchannels
Solution Approach 1:
The patent employs a composite isolation approach that combines the standard ACLR mechanism (providing 45 dB isolation) with an additional precancellation circuit that generates and injects a cancellation reference signal. This composite approach maintains the simplicity of the standard ACLR while adding the cancellation functionality to achieve greater than 100 dB isolation, thereby improving signal reception quality without excessively increasing device complexity.
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 solution achieves significant cancellation performance, suppressing Tx noise leakage into the Rx path, thereby improving signal reception quality and maintaining isolation even when multiple MNOs share the same communication hardware, with negligible insertion loss and noise figure addition.
Implementation Method 1
the cancellation reference signal comprises a complex conjugate of a TX signal leakage signal component of a received RF signal transported in the Rx path of the isolation circuit, wherein within the directional coupler the cancellation reference signal destructively interferes with TX signal leakage signal component
Data Source
AI summary
Systems and methods for signal path isolation for neutral-host hardware are provided. In one embodiment, an isolation circuit for a multiple-subchannel wireless communication transceiver comprises: a Tx path coupled to a transmit path output of a multiple-subchannel transceiver; a Rx path coupled to a receive path input of the transceiver; a precancellation circuit comprising: an isolation adjustment circuit within the transmit path of the isolation circuit, the isolation adjustment circuit comprising a phase shifter and a reflection tuner; a directional coupler within the Rx path of the isolation circuit. The isolation adjustment circuit outputs a reflected wave signal comprising a cancellation reference signal to the directional coupler. The cancellation reference signal comprises a complex conjugate of a TX signal leakage signal component of a signal transported in the Rx path of the isolation circuit. Within the directional coupler the cancellation reference signal destructively interferes with TX signal leakage signal component.