Single Radio Wireless Access Point Power Conservation
Solution Overview
Problem
IEEE 802.11 wireless access points face challenges in reducing power consumption and performing multi-channel traffic relaying using a single radio interface, especially in battery or solar-powered implementations, while maintaining compatibility with legacy IEEE 802.11 end stations.
Innovation Solution
A mechanism where a wireless access point communicates a contention-free period indication in its beacon, allowing it to enter a power conservation mode or relay traffic on a different channel, using a single radio interface, thereby reducing power consumption and enabling multi-channel traffic relaying without the need for dual-radio designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a wireless access point uses a single radio interface for both serving mobile devices and relaying traffic, then device complexity and cost are reduced, but the ability to perform multi-channel traffic relaying is limited
Solution Approach 1:
The access point periodically switches between serving mobile devices on the first channel and relaying traffic on the second channel through time-division multiplexing. The radio interface alternates between communication modes in periodic intervals, allowing single interface to fulfill multiple functions that traditionally required dual interfaces.
2Use of energy by moving object
If the wireless access point enters power conservation mode to reduce power consumption, then energy usage is reduced, but communication with mobile devices is interrupted
Solution Approach 1:
The access point acts as an intermediary that receives traffic from mobile devices during active periods, buffers it, and forwards it during power conservation mode. This allows the radio interface to be powered down or reduced to low-power state while maintaining communication functionality through the buffering mechanism.
Solution Approach 2:
The access point operates in periodic cycles alternating between full-power communication mode and power conservation mode. During power conservation mode, the radio interface is powered down or reduced, and traffic is handled through buffering and periodic wake-up cycles, reducing average power consumption while maintaining service availability.
3Adaptability or versatility
If the wireless access point uses dual-radio design to perform multi-channel traffic relaying, then traffic relaying capability is improved, but device complexity and cost increase
Solution Approach 1:
The single radio interface is designed to perform multiple functions: serving mobile devices on the first channel, relaying traffic on the second channel, and buffering traffic. This multi-functional design eliminates the need for separate dedicated radio interfaces for each function, reducing complexity while maintaining capability.
Solution Approach 2:
The radio interface periodically switches between different operational modes and channels, allowing a single interface to handle multiple roles that traditionally required multiple simultaneous interfaces. The periodic channel switching enables traffic relaying and mobile device service using the same physical radio hardware.
4Reliability
If the wireless access point buffers traffic during power conservation mode, then communication continuity is maintained, but memory requirements and processing complexity increase
Solution Approach 1:
The access point changes operational parameters dynamically: switching between full-power and low-power states, adjusting buffer sizes based on traffic conditions, and modifying wake-up intervals. These parameter adjustments allow the system to maintain communication reliability while adapting power consumption and complexity to current operational needs.
Data Source
AI summary
In one illustrative technique, a contention-free period indication is communicated by a wireless access point (AP) (e.g. a battery-powered AP) to a plurality of mobile communication devices within a beacon of a superframe. The contention-free period indication identifies a duration of a contention-free period within which the mobile devices must refrain from communicating through the AP. During each contention period subframe of each superframe, information is communicated to and/or from the mobile devices through a wireless transceiver of the AP. During each power conservation subframe of each superframe, the wireless transceiver is placed into a power conservation mode which is at least part of the contention-free period. Alternatively, or in combination with the wireless transceiver being placed in the power conservation mode, information for the mobile devices may be communicated to and/or from another AP within each relay subframe of each superframe which is at least part of the contention-free period. Advantageously, power consumption may be reduced in the AP and/or a single radio interface may be utilized in the AP for communications. The durations of the power conservation subframe and the other subframes may be variably adjusted to tradeoff power savings with a real-time capacity requirement of the AP.