Micro-Shutdowns for Wireless Devices in Saturated 802.11 Networks
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Solution Overview
Problem
Current energy-saving methods for wireless devices in 802.11 networks, such as micro-shutdown management, are inefficient in real-world, saturated environments and often compromise performance or break compatibility with the CSMA standard, especially in scenarios with frame bursts.
Innovation Solution
Implementing micro-shutdowns lasting less than a millisecond during overhearing periods, utilizing the NAV counter and interframe times to determine when a wireless device can safely enter a low-energy mode without losing frames, while ensuring compatibility with the 802.11 standard and accounting for hardware limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the wireless card enters sleep mode for long periods to save energy, then energy consumption is dramatically reduced, but connection performance degrades due to significant delays
Solution Approach 1:
The patent implements periodic micro-shutdowns of the wireless card during overhearing periods, where the card enters sleep mode for brief intervals (micro-shutdowns) rather than remaining continuously active. This periodic sleeping approach reduces energy consumption while maintaining acceptable connection performance by limiting shutdown duration to microseconds rather than milliseconds or seconds.
Solution Approach 2:
The patent dynamically adjusts the wireless card's operational state based on real-time channel conditions. The card transitions between active and sleep modes adaptively during overhearing periods, optimizing the balance between energy saving and performance by making state changes dynamic rather than static or purely periodic.
2Reliability
If the wireless card performs passive listening at all times to detect packets, then no packets are missed, but energy consumption increases significantly
Solution Approach 1:
The patent applies partial listening by having the wireless card listen only during necessary periods rather than continuously. During overhearing periods when frames are addressed to other stations, the card performs micro-shutdowns and listens minimally, providing sufficient packet detection capability while reducing energy consumption compared to continuous listening.
Solution Approach 2:
The patent uses the NAV counter to predict future channel activity in advance. By examining the NAV value, the card can determine ahead of time when frames will be transmitted and plan its listening/sleep schedule accordingly, enabling it to skip listening during periods when no relevant frames are expected.
3Use of energy by moving object
If the wireless card shuts down during backoff window to save energy, then energy consumption is reduced, but 802.11 operation is broken as the station must listen during each backoff time slot
Solution Approach 1:
The patent applies micro-shutdowns selectively during specific periods (overhearing periods when frames are addressed to other stations) rather than uniformly during all operations. This localized application ensures protocol compatibility is maintained during critical operations like backoff while achieving energy savings during less critical overhearing periods.
4Use of energy by moving object
If the clock frequency is adaptively reduced during inactivity to save energy, then energy consumption is reduced, but performance degrades in high-load scenarios and energy gain is limited
Solution Approach 1:
The patent changes the operational parameter from clock frequency adjustment to operational state transition (active/sleep). Instead of reducing clock frequency during inactivity, the card transitions to a complete sleep state during micro-shutdowns, achieving more significant energy savings without the performance degradation associated with frequency reduction in high-load scenarios.
Data Source
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AI summary
The present invention relates to an energy-saving method for a wireless device in a telecommunication network. The method comprises: receiving at least one part of a data transmission with information concerning duration, destination address and transmitter address of said transmission; determining compliance with a set of conditions which at least comprises determining, according to the destination address, that the transmission is not addressed to the device; in the event that said conditions are complied with, determining if a sum of times exceeds a minimum shutdown time previously established according to hardware limitations of the device, where said sum of time comprises at least one counter set according to the information concerning duration; and in the event that the sum is greater than said minimum time, performing a micro-shutdown of the device with a duration equal to the value of said sum of times.