Ambient IoT D2R Retransmissions With Energy-Aware Time Spacing
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Solution Overview
Problem
Ambient IoT devices face challenges in power saving and collision reduction due to their large number and limited capabilities, requiring careful resource scheduling and energy harvesting management to avoid interference and ensure reliable communication.
Innovation Solution
Implementing frequency diversity techniques, resource scheduling based on local measurements, and relaying methods to manage re-transmissions and energy harvesting, including pre-configuration and scheduled approaches for D2R transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple retransmissions are performed to improve link reliability, then communication reliability is improved, but system interference increases
Solution Approach 1:
The patent applies dynamics by making the number of retransmissions adaptive rather than fixed. The gNB schedules retransmissions dynamically based on channel conditions, device type, and energy harvesting status. This allows the system to perform more retransmissions when channel conditions are poor (improving reliability) while reducing retransmissions when channel conditions are good (reducing interference), thus resolving the contradiction between reliability and interference.
Solution Approach 2:
The patent changes key parameters including the number of retransmissions, time separation between retransmissions, and frequency resources used. By adjusting these parameters based on channel quality indicators (CQI), device type, and energy availability, the system optimizes the balance between achieving reliable communication and minimizing system interference from multiple retransmissions.
2Productivity
If consecutive retransmissions are performed with short time separation, then resource efficiency is improved, but energy harvesting ability is compromised
Solution Approach 1:
The patent applies preliminary action by scheduling energy harvesting time before retransmissions for devices that require it (e.g., Type-2a devices). The gNB identifies devices that need energy harvesting and allocates time resources accordingly before scheduling retransmissions, ensuring devices have sufficient energy available when needed without compromising the overall retransmission schedule.
Solution Approach 2:
The time separation between retransmissions is made dynamic based on device type and energy harvesting requirements. For devices that perform energy harvesting (e.g., Type-2a), the patent inserts appropriate time separations between retransmissions to allow energy accumulation. For devices that don't require energy harvesting, retransmissions can be scheduled with minimal separation, thus maintaining resource efficiency while accommodating energy constraints.
3Area of stationary object
If a large number of ambient IoT devices deploy, then system coverage is improved, but collision probability increases
Solution Approach 1:
The patent applies segmentation by dividing the system into different device categories (Type-1, Type-2a, Type-2b) with different communication characteristics and resource requirements. This segmentation allows the system to manage large numbers of devices more effectively by applying different scheduling strategies to different device types, reducing collisions while maintaining broad coverage.
Solution Approach 2:
The patent implements feedback mechanisms where devices report channel conditions, energy status, and transmission outcomes to the gNB. The gNB uses this feedback to adjust scheduling decisions, allocate resources more efficiently, and predict potential collisions before they occur, thereby managing collision probability even as system coverage expands to include large numbers of devices.
Data Source
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AI summary
Apparatus and methods are disclosed for performing D2R and R2D transmission in an ambient IoT system. A method performed by an ambient IoT device includes receiving (1301), from a reader, a control indication to trigger a D2R transmission; identifying (1302) a number of base retransmissions to perform for the D2R transmission; performing (1303) an initial transmission of the D2R transmission; and performing (1304) base retransmissions of the D2R transmission based on the number of base retransmissions. Consecutive base retransmissions among the base retransmissions of the D2R transmission are separated from each other by a time domain interval based on a CW energy harvesting ability of the ambient IoT device.