Wireless Wake-on-LAN Power Management via Inverted Handshake
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Solution Overview
Problem
The implementation of Wake-on-LAN in wireless LANs is hindered by high power consumption and the need for frequent scanning and association with access points, which increases power usage and load on the power subsystem.
Innovation Solution
A system and method that allows a computer to receive broadcast or multicast frames without handshaking with an access point, using a receiving mechanism to monitor frames and determine the presence of a magic packet, enabling power-on based on IEEE802.11 standards, thereby reducing power consumption and eliminating the need for transmission and scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a computer transmits wireless frames to associate with an access point and perform handshaking, then it can establish connection and communicate, but power consumption increases significantly (1.2 to 1.5W during transmission)
Solution Approach 1:
Instead of the client PC transmitting frames to associate with the access point, the access point transmits broadcast/multicast frames containing wake-up information to the client PC. This reverses the traditional communication direction and eliminates the need for client transmission, thereby reducing power consumption from 1.2-1.5W to approximately 600mW or less.
Solution Approach 2:
The access point acts as an intermediary that receives wake-up packets from the controller and transmits them as broadcast/multicast frames to the client PC. This intermediary approach allows the client to receive wake-up information without needing to transmit association frames, solving the power consumption problem while maintaining connection reliability.
2Reliability
If a client PC performs scanning to identify the access point, then it can find the correct access point for communication, but power consumption increases and time is lost
Solution Approach 1:
The access point pre-configures and transmits broadcast/multicast frames containing wake-up information and identification data. The client PC can identify the correct access point by receiving these pre-transmitted frames, eliminating the need for active scanning and reducing both power consumption and time required for access point identification.
3Use of energy by moving object
If the computer remains in sleep mode during DTIM periods, then power consumption is reduced, but the ability to receive data packets is limited
Solution Approach 1:
The access point continuously transmits broadcast/multicast frames containing wake-up information and data packets at regular intervals (including DTIM periods). The client PC remains in sleep mode during non-DTIM periods to save power, but can reliably receive data packets during DTIM periods when the access point actively transmits, thus maintaining continuous data reception capability with minimal power consumption.
Data Source
AI summary
In a wireless LAN mini PCI module connected to a computer, an RF module receives through an antenna a broadcast frame and/or a multicast frame transmitted from a predetermined wireless access point in a state where a main power supply for a system main unit is not on, a magic packet included in the broadcast frame and/or the multicast frame is recognized, and a signal for turning on the main power supply is output from a base band processor to the system main unit.