Backscatter Channel Access Using Harvesting Rate-Based Backoff
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Solution Overview
Problem
In energy harvesting-based communication systems, IoT devices face challenges in accessing wireless channels efficiently due to varying energy harvesting rates and physical distances from the reader, leading to potential uplink signal collisions and unequal transmission opportunities.
Innovation Solution
A channel access method is proposed where devices calculate their harvesting rate, determine a corresponding channel access resource, and transmit backscattered signals using a random back-off scheme, adjusting based on response signals to minimize collisions and optimize resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices transmit uplink signals without considering energy harvesting rates, then transmission simplicity is maintained, but signal collisions increase and channel access fairness deteriorates
Solution Approach 1:
The patent changes the parameter of channel access timing by introducing harvesting rate-based random back-off values. Devices with different harvesting rates select different back-off durations, transforming a uniform access mechanism into a differentiated one that accounts for energy availability, thereby improving fairness without requiring complex resource allocation protocols
Solution Approach 2:
The patent introduces dynamic adjustment of transmission timing based on harvested energy levels. Devices dynamically determine their back-off duration according to their current harvesting rate, making the channel access mechanism adaptive to varying energy conditions rather than static, which resolves the contradiction between simplicity and fairness
2Productivity
If devices with different harvesting rates access the channel simultaneously, then channel utilization is maximized, but collision probability increases
Solution Approach 1:
The patent applies preliminary action by having devices determine their random back-off value before attempting channel access. This pre-calculation based on harvesting rate creates a staged access pattern where devices prepare their transmission timing in advance, reducing collisions while maintaining high channel utilization through coordinated staggered access
3Loss of energy
If uniform channel access resources are allocated to all devices, then resource allocation simplicity is maintained, but energy efficiency deteriorates due to unnecessary transmissions
Solution Approach 1:
The patent changes the parameter of channel access timing by introducing harvesting rate-based random back-off values. Devices with different harvesting rates select different back-off durations, transforming a uniform access mechanism into a differentiated one that accounts for energy availability, thereby improving fairness without requiring complex resource allocation protocols
Solution Approach 2:
The patent converts the potential harm of varying energy levels into a beneficial staggered access pattern. By using harvesting rate differences as the basis for random back-off values, the system transforms what could be a source of inequality into a mechanism that naturally distributes access timing, reducing collisions and energy waste from failed transmissions
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 method enables fair and efficient channel access for IoT devices with different energy harvesting capabilities, reducing collisions and optimizing radio channel resource utilization.
Implementation Method 1
receiving a carrier wave from the reader; generating a backscattered signal including a second subframe by reflecting the carrier wave
Implementation Method 2
generating a backscattered signal including a second subframe by reflecting the carrier wave
Data Source
AI summary
A method of a device may comprise: receiving, from a reader, a first subframe including information on channel access resources for harvesting rate stages; determining a channel access resource according to a harvesting rate of the device, based on the information on the channel access resources; receiving a carrier wave from the reader; generating a backscattered signal including a second subframe by reflecting the carrier wave; and transmitting the backscattered signal to the reader by using the channel access resource.