Dynamic Power Chain Management in 802.11n Access Points
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Solution Overview
Problem
Modern 802.11n wireless access points consume excessive power when operating in high throughput modes, and there is a need for an automatic power reduction mechanism when they are in Legacy modes.
Innovation Solution
Implementing a method where only one receive chain is powered up when the radio subsystem is idle, and all required transmit chains are powered up only when 802.11n frames need to be transmitted, with adjustable turn-on and turn-off times based on circuitry requirements, and leaving higher-power elements like transmit power amplifiers powered down for power savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmit/receive chains are activated in 802.11n access points to support high throughput modes, then data transmission capability is improved, but power consumption increases significantly
Solution Approach 1:
The patent implements dynamic power management by adjusting the number of active transmit/receive chains based on the operating mode. In legacy modes (802.11a/b/g), only one radio chain is activated, while in HT 802.11n mode, multiple chains (2-4) are activated. The system dynamically switches between these configurations based on the detected client capability and selected transmission mode, thereby optimizing the balance between data transmission capability and power consumption.
Solution Approach 2:
The patent changes the operational parameters of the radio subsystem by modifying the number of active transmit/receive chains according to the transmission mode. The system monitors the operating mode (legacy vs. high throughput) and adjusts the chain configuration accordingly, transforming the power consumption characteristic from a fixed high value to a variable value that adapts to operational needs.
2Reliability
If all transmit chains are powered up continuously to ensure readiness for 802.11n transmissions, then transmission readiness is improved, but power consumption increases during idle periods
Solution Approach 1:
The system dynamically adjusts the power state of transmit chains based on operational requirements. During idle periods in legacy modes, the system powers down unnecessary chains to reduce energy consumption. When 802.11n transmissions are detected or anticipated, the system quickly powers up the required number of chains, ensuring transmission readiness is maintained only when needed.
Solution Approach 2:
The patent implements periodic monitoring of transmission requirements and adjusts power states accordingly. The system periodically checks whether 802.11n frames need to be transmitted and adjusts chain power states in response, creating a rhythmic pattern of power consumption that aligns with actual transmission needs rather than maintaining continuous high-power operation.
Data Source
AI summary
Embodiments of the invention are directed to power savings in Access Points (APs). Legacy 802.11 modes such as 802.11a/b/g use one transmitter/receive chain per radio. High Throughput (HT) 802.11n modes use multiple (2, 3, or more) transmit/receive chains per radio. Power consumed by the AP may be reduced by powering off unused transmit and/or receive chains. Multiple transmit chains are only powered up when HT 802.11n transmissions requiring them are made. Using protected mode signaling, the AP powers up multiple receive chains needed for HT 802.11n reception on receiving a Request to Send (RTS) packet indicating that an 802.11n client wishes to send 802.11n HT data. Transmit and/or receive chains may be powered up with minimum on times. Only certain elements of a chain may be powered up and down, with those elements requiring a great deal of settling time left powered on. Transmit chains may be powered up on the reception of RTS-based information indicating arrival of HT 802.11 data.