MSIM Transceiver Power Backoff for Page Signal Desense Mitigation

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Solution Overview

Problem

In wireless communication devices with multi-subscriber identity module (MSIM) applications, such as dual-SIM-dual-standby (DSDS), electromagnetic interference (desense) occurs due to reciprocal mixing of transmission and reception signals with poor phase noise synthesizers, leading to difficulty in decoding page signals.

Innovation Solution

Adaptive transmission power backoff (Tx backoff) is implemented based on channel separation and harmonic relations to mitigate desense, using on-the-fly computations to reduce transmission power levels, especially for low-cost, low-area ring oscillator-based synthesizers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transmission power is reduced to mitigate desense and enable page decoding, then reception reliability is improved, but transmission power efficiency deteriorates

Engineering Contradiction:

Improvepage signal decoding reliabilityVSAvoidtransmission power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts transmission power based on operational mode: using reduced first transmit power during page signal reception to mitigate desense, and switching to higher second transmit power for normal transmissions. This dynamic power adaptation resolves the contradiction by optimizing power levels according to real-time reception requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements periodic transmit power backoff during specific time durations when page signals are being received, using a first transmit power lower than the second transmit power used at other times. This periodic adjustment of power levels enables reliable page decoding while maintaining normal transmission power efficiency during non-reception periods.

Inventive Principle:

Principle #19Periodic action

2Use of energy by stationary object

If low-cost ring oscillator-based synthesizers are used to reduce area and power consumption, then device cost and power usage are reduced, but phase noise performance deteriorates causing reciprocal mixing

Engineering Contradiction:

Improvepower consumptionVSAvoidreciprocal mixing noise

Core Design Contradiction:

Use of energy by stationary objectVSObject-affected harmful factors

Solution Approach 1:

The system converts the harmful effect of poor phase noise from ring oscillator-based synthesizers into a manageable parameter by implementing adaptive transmit power backoff. Instead of using high-cost synthesizers to eliminate reciprocal mixing, the system accepts the phase noise limitation and compensates through dynamic power reduction during page reception, thereby using low-cost synthesizers effectively.

Inventive Principle:

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

Solution Approach 2:

The system changes the transmit power parameter adaptively based on the phase noise characteristics of the synthesizer and the reception requirements. By adjusting power levels according to the synthesizer's phase noise performance, the system enables successful page decoding with low-cost ring oscillator-based synthesizers that would otherwise produce excessive reciprocal mixing noise.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If transmit power backoff is applied during page signal reception, then desense mitigation is achieved, but transmission throughput is reduced

Engineering Contradiction:

Improvepage signal reception qualityVSAvoidtransmission throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system applies transmit power backoff periodically only during the specific time durations when page signals are being received on the second subscriber identity module, while maintaining normal transmission power at other times. This selective and temporary power reduction minimizes the impact on overall transmission throughput while ensuring reliable page signal reception.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system applies partial transmit power backoff - using a first transmit power that is lower than but not necessarily minimal, sufficient to enable page signal decoding while maintaining reasonable transmission efficiency. This partial adjustment balances desense mitigation with throughput preservation.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250254627A1Adaptive power control as a desense mitigation in a multi-subscriber identify module (MSIM) application

Publication Date: 2025.08.07 QUALCOMM INC

AI summary

Certain aspects of the present disclosure are directed towards methods and apparatus for wireless communication. An example method generally includes: determining a first transmit power to facilitate decoding of a page signal; receiving, for a time duration, the page signal using a first receive chain; and performing a transmission using the first transmit power during the time duration in which the page signal is being received, wherein the transmission is performed using a second transmit power after the time duration, the second transmit power being greater than the first transmit power.