Physical Layer Signal Encoding for WLAN Power Saving
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Solution Overview
Problem
In conventional WLAN systems, terminals waste power and time due to inefficient power saving mechanisms, as they must associate with an Access Point to discover service information, leading to system inefficiency and battery waste, especially when the service is not required.
Innovation Solution
A method and apparatus for transmitting and receiving information that load network synchronization, contention window size, and collision detection information using a physical layer signal in a distributed node system, where terminals can efficiently recognize messages through orthogonality of the physical layer signal, reducing power consumption by allowing operation only during specific slots within a frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If terminals listen for beacon start timing information to enable power saving, then power consumption is reduced, but system efficiency deteriorates due to battery waste and time waste when services are not required
Solution Approach 1:
The patent applies preliminary action by enabling terminals to perform service discovery before formal association with the Access Point. The physical layer signal transmitted by the AP contains service information that terminals can decode while in sleep mode, allowing them to determine whether to associate in advance. This prevents wasted power and time on association processes for services that are not available, thereby resolving the contradiction between power saving and system efficiency.
2Loss of information
If terminals perform association process with AP to obtain service information, then discovery information is obtained, but power is wasted when the service is not required
Solution Approach 1:
The patent extracts service information from the association process and places it in the physical layer signal transmitted during beacon periods. Specifically, the service information element is included in the MAC header or data portion of the beacon frame, allowing terminals to obtain discovery information passively while in sleep mode without needing to perform the full association process. This separates the information acquisition function from the power-intensive association procedure.
3Loss of information
If terminals listen for the entire beacon to obtain service information, then complete discovery information is obtained, but power consumption increases
Solution Approach 1:
The patent applies partial action by enabling terminals to listen for only a portion of the beacon signal specifically containing service information, rather than the entire beacon. The service information is placed in the MAC header or early data portion of the beacon frame, allowing terminals to wake up briefly, decode the critical service information element, and return to sleep mode without processing the complete beacon. This reduces the listening duration and power consumption while still obtaining necessary discovery information.
Data Source
AI summary
When a transmitter transmits a first Timing Offset Indication iDentifier (TOID) of a plurality of TOIDs representing timing offset of a frame, the transmitter determines a first codeword corresponding to the first TOID of a plurality of codewords representing a subcarrier. The transmitter allocates a busy tone to a first subcarrier that the first codeword represents. The transmitter transmits the busy tone.