Event Offset Allocation for Battery-Powered Wireless Devices
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Solution Overview
Problem
Battery-powered devices in wireless networks face challenges in conserving power due to their limited battery life, especially in applications like water and gas metering where devices need to operate for extended periods, necessitating efficient power management techniques.
Innovation Solution
The implementation of event offsets, where mains-powered devices assign time offsets to battery-powered devices to optimize their wake and sleep cycles, allowing for uniform distribution of communications and minimizing the time spent in active power consumption, thereby extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery-powered devices continuously monitor and communicate in wireless networks, then network communication reliability is improved, but battery power consumption increases
Solution Approach 1:
The patent implements periodic wake-up cycles where battery-powered devices transition between sleep and active states. Devices wake up at predetermined intervals to check for downlink events, then return to sleep mode. This periodic action maintains network communication reliability by ensuring devices are awake when needed while dramatically reducing average power consumption compared to continuous operation.
Solution Approach 2:
The system uses preliminary actions by having devices wake up before actual communication is needed to check for event notifications. The wake-up cycle is predetermined and synchronized with network transmission schedules, allowing devices to prepare for potential communication without remaining continuously active, thus balancing reliability and power savings.
2Productivity
If battery-powered devices wake up more frequently to check for communications, then communication responsiveness is improved, but time spent in active state increases
Solution Approach 1:
The patent establishes periodic wake-up cycles with optimized intervals that balance communication responsiveness with time spent active. Devices wake up at regular intervals to check for downlink events, maintaining adequate responsiveness for most applications while minimizing active time through the periodic sleep-wake pattern. The period length is tuned to match typical network communication frequencies.
Solution Approach 2:
The system employs self-service mechanisms where devices autonomously manage their wake-up cycles without continuous network control. Each device independently monitors for downlink events during its allocated wake-up period and self-manages the transition between active and sleep states, optimizing the balance between responsiveness and active time based on local needs and network conditions.
Data Source
AI summary
Techniques for allocating event offsets within a period of transmission are described. A mains-powered device (MPD) may act as a “parent” to one or more battery-powered devices (BPDs). The MPD may assign “event offsets” to each BPD. The event offset is a time by which the BPD's timeslot is “offset” from the start of a periodic cycle of transmissions by the MPD. Thus, each event offset indicates a time that the BPD must be “awake,” i.e., operating its radio receiver and/or performing other functionality. A BPD may spend a substantial fraction of its time in a “sleep” mode, wherein less power is used and fewer functions are performed than during a period of that BPD's event offset. Another BPD may have a different event offset. Communications by the MPD with each child BPD may be substantially uniformly distributed over the period. To increase efficiency, groups of BPDs may receive multicasts.