Asynchronous Uplink Trigger Configuration for Low-Power IoT Grants
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Solution Overview
Problem
Wireless communications systems face challenges in efficiently transmitting asynchronous uplink triggers due to potential frequency errors and power constraints, particularly in devices with limited power capabilities such as ultra-light IoT devices, which operate without network-synchronized timing.
Innovation Solution
A network entity provides an uplink trigger configuration with parameters for UE devices to transmit energy scheduling requests (ESRs) and communication scheduling requests (CSRs) asynchronously, including monitoring windows and waveforms, with retransmissions if grants are not received, and supports devices with active and backscatter radios to manage power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If asynchronous uplink trigger transmission is implemented without network-synchronized timing, then power consumption is reduced and device complexity is lowered, but frequency errors occur and communication reliability deteriorates
Solution Approach 1:
The network entity pre-configures uplink trigger parameters including frequency offset compensation values and monitoring window timings before the UE transmits asynchronous triggers. This preliminary configuration enables the UE to compensate for frequency errors without requiring continuous network synchronization, reducing power consumption while maintaining communication reliability
Solution Approach 2:
The system dynamically adjusts frequency offset parameters and monitoring window durations based on channel conditions and device power states. By changing these parameters adaptively, the system maintains reliable communication while allowing devices to operate in low-power asynchronous modes without continuous timing synchronization
2Reliability
If monitoring window duration is extended to ensure reliable grant reception, then communication reliability improves, but power consumption increases and device efficiency decreases
Solution Approach 1:
The monitoring window duration is dynamically adjusted based on channel conditions, device power state, and historical grant reception success rates. During stable channel conditions, the window is shortened to reduce power consumption. During unstable conditions or initial connection phases, the window is extended to ensure reliable grant reception, optimizing the trade-off between reliability and power consumption
3Reliability
If retransmission mechanisms are implemented for uplink triggers, then communication reliability improves, but device complexity and processing overhead increase
Solution Approach 1:
The network entity provides feedback through downlink grants indicating whether uplink trigger transmissions were successfully received. UEs use this feedback to determine whether retransmission is necessary, implementing a simple feedback-driven retransmission mechanism that improves reliability without significantly increasing device complexity
Solution Approach 2:
The system implements selective retransmission where only triggers that fail to receive acknowledgments are retransmitted, rather than continuously retransmitting all triggers. This partial action approach maintains reliability for critical transmissions while minimizing the complexity and overhead associated with comprehensive retransmission protocols
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Some wireless communications systems may support asynchronous uplink triggers. For example, a user equipment (UE) may receive, from a network entity, an indication of parameters associated with an uplink trigger configuration, where the parameters are associated with energy scheduling request, communication scheduling requests, or both. Additionally, the UE may transmit, via an active radio (AR), an uplink trigger based on the uplink trigger configuration, where the uplink trigger includes the energy scheduling requests, the communication scheduling requests, or both. Further, the UE may monitor, via a backscatter radio (BR), for energy grants, communication grants, or both, based on the uplink trigger, where the monitoring is based on the uplink trigger configuration. In some cases, the UE may receive, via the BR, the energy grants, the communication grants, or both, based on the monitoring.