NFC Tag Power Management for Battery Level Optimization
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Solution Overview
Problem
Mobile communication devices with NFC capabilities face challenges in maintaining battery life when operating in card emulation mode, as they need to continuously transmit and receive data without being able to make or receive calls or access the internet, leading to reduced battery power and limited functionality.
Innovation Solution
The implementation of a power management system that allows the NFC device to transition through various power modes, including a 'keep alive' memory mode where the device harvests power from an external field, ensuring secure information is retained even when battery power is low, and using a secure element that draws minimal power to maintain card emulation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the NFC device operates in card emulation mode continuously to maintain functionality, then the card emulation capability is preserved, but the battery power is depleted faster
Solution Approach 1:
The system dynamically transitions between different power modes (full power mode, low power mode, and keep alive mode) based on operational needs and battery status. This allows the NFC device to maintain card emulation functionality when needed while conserving battery power during periods of inactivity or low-demand operations.
Solution Approach 2:
The patent changes the power consumption parameters by introducing a keep alive mode that significantly reduces battery power usage while maintaining minimal NFC functionality. This parameter change enables the device to extend its operational life from hours to days or weeks on a single battery charge.
2Reliability
If the device uses non-volatile memory to retain secure information, then data retention is improved, but the device cost increases
Solution Approach 1:
The patent replaces expensive non-volatile memory with a cheaper alternative that uses minimal battery power to retain secure information temporarily. The secure element maintains data in a low-power state, providing a cost-effective solution that achieves the same functional outcome without the high cost of non-volatile memory components.
3Duration of action of moving object
If the NFC device harvests power from external fields to extend battery life, then the operational duration is extended, but the power harvesting capability is limited
Solution Approach 1:
The system uses partial power harvesting from external fields, supplementing rather than completely replacing battery power. This partial action approach extends operational duration significantly while avoiding the need for excessive or complete power independence, balancing the limitations of power harvesting technology with practical operational requirements.
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 optimizes battery life by allowing NFC devices to operate in card emulation mode for extended periods, even when battery power is low, ensuring continued functionality for several days until recharge, and reducing device costs by using a secure element instead of non-volatile memory.
Implementation Method 1
the device harvests power from an external field
Implementation Method 2
the reader actively generates an RF field that can power a passive tag
Data Source
AI summary
A mobile communication device has a processor, a radio, a near field communication (NFC) device, a battery, and memory for storing data. The power level of the battery is measured. When the measured power level is above a first predetermined level, power is provided to the radio to allow communication. Sufficient power is provided to operate the NFC device as a reader and a tag. When the measured power level of the battery falls below the first predetermined level, battery power to the radio is shut off. Sufficient power is maintained to the NFC device to allow it to operate only as a tag. Sufficient power is maintained to the memory to retain the data stored in the memory. When the measured power level of the battery falls below a second predetermined level, the NFC device is required to harvest all of its power from the field.