Sub-band Selection for Full Duplex Base Station Self-Interference

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Solution Overview

Problem

Full duplex operation in RF communication systems faces challenges due to self-interference, where the receiver is overloaded by the transmitter's signal, leading to nonlinear operation and potential damage, especially in cellular base stations that need to transmit and receive simultaneously within the same frequency band.

Innovation Solution

A method is described to determine the self-interference channel response across multiple sub-bands of a cellular frequency channel, identifying a sub-band with minimal self-interference and adjusting the receiver sensitivity to operate within a linear region, allowing simultaneous transmission and reception by estimating the coupled transmit power level and adjusting the receiver's operational level accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the receiver operates with high sensitivity to detect weak signals, then the receiver can communicate over substantial distances, but the receiver becomes vulnerable to self-interference and nonlinear operation when transmitting at high power levels

Engineering Contradiction:

Improvereceiver sensitivityVSAvoidreceiver operation stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The frequency band is divided into multiple sub-bands, and the self-interference channel response is measured and analyzed across these sub-bands to identify specific sub-bands with minimal self-interference. This segmentation allows the system to operate in frequency portions where the receiver remains protected from transmitter self-interference while maintaining high sensitivity for distant communications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sub-bands are evaluated for their specific self-interference characteristics, and the system selects sub-bands with locally optimal properties (minimal self-interference) for operation. This allows the receiver to operate with high sensitivity in specific frequency regions while avoiding the harmful effects in other regions.

Inventive Principle:

Principle #3Local quality

2Length of moving object

If the transmitter uses high power levels to overcome link losses over substantial distances, then communication range is extended, but self-interference at the receiver increases causing nonlinear operation and potential damage

Engineering Contradiction:

Improvecommunication rangeVSAvoidself-interference

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The available frequency spectrum is segmented into multiple sub-bands, and the system measures self-interference characteristics across these segments. By selecting sub-bands with minimal self-interference, the system enables high-power transmission to extend communication range while preventing the harmful self-interference effects from damaging the receiver.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent measures and characterizes the self-interference channel response to identify frequency regions where self-interference is naturally minimized. This converts the potentially harmful effect of self-interference into a useful guide for selecting optimal operating frequencies, allowing high-power transmission without receiver damage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If full duplex operation is implemented in the same frequency band, then spectral efficiency is improved, but self-interference between transmitter and receiver degrades performance

Engineering Contradiction:

Improvespectral efficiencyVSAvoidcommunication performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The frequency band is divided into multiple sub-bands, and the self-interference channel response is measured across these sub-bands. The system then selects specific sub-bands with minimal self-interference for simultaneous transmit and receive operations, enabling full duplex operation that maintains both high spectral efficiency and communication performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically selects operating sub-bands based on measured self-interference characteristics, changing the frequency parameter to optimize the balance between spectral efficiency and performance reliability. This allows full duplex operation to achieve both high productivity and maintained reliability by adapting to actual channel conditions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250097854A1Sub-band selection at cellular base station for non-overlapped or partially overlapped full duplex operation

Publication Date: 2025.03.20 AT&T INTELLECTUAL PROPERTY I L P

AI summary

Aspects of the subject disclosure may include, for example, determining a self-interference channel response of a transceiver of a mobile base station having a transmitter and a receiver. The self-interference channel response spans multiple sub-bands of a predetermined mobile cellular frequency channel. A first sub-band of the multiple sub-bands is identified according to the self-interference channel response and, an estimate is determined, at the receiver, of a first coupled transmit power level of the transmitter when operating within the first sub-band. A receiver sensitivity is adjusted according to the first coupled transmit power level to obtain an adjustment adapted to increase receiver sensitivity, while restricting operation of the receiver to a substantially linear region. The adjustment allows a transmission within the first sub-band and a reception within a second sub-band of the plurality of sub-bands to occur simultaneously at the mobile base station. Other embodiments are disclosed.