Wake-Up Signal Resource Allocation for IoT Power Savings
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing power consumption and synchronizing devices, particularly in idle mode, due to the need for frequent monitoring of paging messages, which leads to unnecessary resource usage and battery drain in low-complexity devices like those used in IoT applications.
Innovation Solution
The implementation of a Wake-Up Signal (WUS) system that allows devices to determine if a paging message is present in advance of the scheduled paging occasion, reducing the need for continuous monitoring and enabling devices to enter low power mode when no message is detected, thereby conserving energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices continuously monitor paging messages to maintain synchronization with the network, then synchronization reliability is improved, but power consumption increases
Solution Approach 1:
The network transmits a wake-up signal before the scheduled paging occasion to indicate in advance whether a paging message will be sent. This preliminary action allows the device to determine beforehand whether it needs to wake up for the paging occasion, avoiding unnecessary power consumption while maintaining synchronization reliability.
Solution Approach 2:
A wake-up signal is introduced as an intermediary between the network and the device. This intermediary carries paging indication information and allows the device to make informed decisions about whether to activate full reception, thereby resolving the contradiction between maintaining synchronization and conserving energy.
2Reliability
If devices wake up before every paging occasion to check for messages, then message detection reliability is improved, but unnecessary resource usage increases
Solution Approach 1:
The wake-up signal provides preliminary information about the presence of paging messages before the actual paging occasion. This allows devices to avoid waking up and consuming resources when no messages are present, while ensuring reliable message detection when messages are actually sent.
Solution Approach 2:
Instead of requiring full paging message monitoring at every occasion, the system uses a partial action approach where devices only fully activate when the wake-up signal indicates a message is present. This reduces energy waste while maintaining detection reliability for actual messages.
3Use of energy by moving object
If devices enter low power mode to conserve energy, then power consumption is reduced, but ability to receive paging messages may be compromised
Solution Approach 1:
The wake-up signal is transmitted in advance of the paging occasion, providing devices with early notice of upcoming messages. This preliminary action gives devices sufficient time to exit low power mode and prepare for message reception, ensuring reliable reception while minimizing the duration of high-power operation.
Solution Approach 2:
The device dynamically adjusts its power state based on the wake-up signal indication. When a message is indicated, the device transitions from low power mode to active reception mode. When no message is indicated, the device remains in low power mode. This dynamic adaptation resolves the contradiction between power conservation and message reception reliability.
Data Source
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AI summary
A method of operating an infrastructure equipment, which forms part of a wireless communications network and configured for communicating with one or more communications devices comprises forming a downlink signal for transmission via a wireless access interface. The wireless access interface comprises in a frequency dimension resource elements for carrying sub-carriers of Orthogonal Frequency Division Multiplexed (OFDM) symbols, the resource elements being formed in the frequency dimension into a plurality of blocks of resource elements, and in a time dimension the wireless access interface is divided into time units, each of the time units for carrying a number of OFDM symbols. The time units may be for example sub-frames of the wireless access interface. The forming of the downlink signal comprises selecting a plurality of component-signals from a set of component-signals, each of the component-signals from the set of component-signals being formed from a sequence of signal samples for transmission in one of the blocks of resource elements and in one of the time units by the number of OFDM symbols, each of the component-signals being detectable by a narrow bandwidth receiver, and selecting for each of the plurality of component-signals one or more of the plurality of the blocks of resource elements and one or more of the time units to transmit the component-signal. The sequence of signal samples may be for example a narrow band Internet of Things Wake-up Signal (NB-IoT WUS) formed for example from a Zadoff-Chu sequence and carried by a number of OFDM symbols in one of the blocks of resource elements of the wireless access interface. In one example, the plurality of component-signals can be used to form a wider bandwidth wake-up signal such as one which might be used for an eMTC device.