Preamble Detector Power Management for Wireless Stations
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Solution Overview
Problem
In congested wireless local area networks, wireless stations face significant power consumption issues when waking up to receive delayed beacon frames due to network congestion or interference, leading to unwanted power drain during prolonged waiting periods.
Innovation Solution
A method and apparatus for low power preamble detection in wireless stations, involving repetitive preamble detection cycles with shorter detection intervals and sleep intervals, where power is applied only during preamble detection and processing, and removed during sleep periods, using a phase lock loop and preamble processor to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the station remains powered up to wait for delayed beacon frames, then the station can receive the beacon, but power consumption increases significantly
Solution Approach 1:
The station enters a repetitive series of preamble detection cycles, periodically activating the receiver for short detection intervals rather than remaining continuously powered up. This periodic activation significantly reduces power consumption while still ensuring beacon frames are detected when they arrive.
Solution Approach 2:
The system performs preliminary preamble detection before the full beacon frame arrives. By detecting the preamble portion first and then entering sleep mode if no valid preamble is found, the station avoids the high power consumption of maintaining the full receiver active throughout the entire beacon interval.
2Use of energy by moving object
If the station uses shorter preamble detection intervals, then power consumption is reduced, but detection reliability may be compromised
Solution Approach 1:
The preamble detection process is segmented into multiple short detection intervals rather than using a single long detection period. Each interval is short enough to allow power savings, but the cumulative effect of multiple intervals ensures reliable detection. The receiver is reactivated between intervals to continue monitoring for preambles.
Solution Approach 2:
The system uses feedback from each detection interval to determine whether to continue monitoring or enter sleep mode. If a valid preamble is detected during any interval, the station remains active to receive the full beacon frame. If no preamble is detected after multiple intervals, the system enters sleep mode, using the detection results to guide power management decisions.
Data Source
AI summary
A wireless receiver has a preamble detection apparatus and method which waits until the expected arrival of a beacon frame, after which power is cyclically applied during a preamble detection interval and a sleep interval until a preamble is detected. The preamble detector has a first mode with a longer preamble detection interval and a second mode with a shorter preamble detection interval. During the preamble detection interval, power is applied to receiver components, and during the sleep interval, power is not applied. The duration of the preamble detection interval is equal to a preamble sensing interval, and if a preamble is detected, power remains applied to a preamble processor for a preamble processing interval. The duration of the sleep interval is the duration of a long preamble less the sum of two times the preamble detection interval plus the preamble processing interval. Phase lock loop (PLL) power is applied a PLL settling time prior to and during the preamble detection interval.