TV White Space Beacon Power Management
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Solution Overview
Problem
Wireless LAN devices operating in TV white space lack a method to identify maximum transmit power levels, leading to potential interference with adjacent TV broadcasting services, as existing standards like IEEE 802.11af do not provide adequate mechanisms for dynamic power management based on the presence of TV signals in adjacent channels.
Innovation Solution
The introduction of an information element and frame structure within beacon, probe response, association response, and reassociation response frames to announce channel power management information, including operating class, channel number, and regulatory maximum transmit power, allowing devices to dynamically adjust their power settings to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wireless LAN devices operate in TV white space without power management mechanisms, then device simplicity is maintained, but interference with adjacent TV broadcasting services occurs
Solution Approach 1:
The patent implements preliminary action by announcing channel power management information in advance through beacon frames before actual transmission occurs. The access point includes maximum transmit power values for different channels in the beacon frame, allowing stations to pre-configured their power levels according to the announced information, thus preventing interference with adjacent TV channels before it can occur.
Solution Approach 2:
The patent implements feedback by continuously announcing channel power management information through periodic beacon frames. The access point monitors the TV white space environment and updates the maximum transmit power values in beacon frames, providing ongoing feedback to stations about safe power levels. This allows the system to adapt to changing conditions and maintain non-interference with adjacent TV broadcasting services.
2Object-affected harmful factors
If dynamic power adjustment based on adjacent channel conditions is implemented, then interference prevention is improved, but information processing complexity increases
Solution Approach 1:
The patent implements segmentation by dividing the channel power management information into distinct, structured fields within the beacon frame. The information element includes separate maximum transmit power value fields for different channels, allowing stations to extract and process only the relevant power values for their operating conditions. This segmented structure simplifies information processing compared to a monolithic data structure.
Solution Approach 2:
The patent implements parameter changes by dynamically updating the maximum transmit power values in the beacon frame based on detected adjacent channel conditions. When the access point detects TV signals in adjacent channels, it modifies the power parameters in subsequent beacon frames to reflect reduced maximum power levels, enabling stations to adapt their transmission power accordingly to prevent interference.
3Loss of information
If channel power management information is announced in beacon frames, then power level identification is enabled, but frame processing time increases
Solution Approach 1:
The patent implements preliminary action by including channel power management information in periodically transmitted beacon frames, which are already part of the standard Wi-Fi protocol. Stations expect and process beacon frames at regular intervals, so the additional power management information is integrated into an existing processing rhythm rather than requiring separate processing cycles. This minimizes the incremental time overhead.
Solution Approach 2:
The patent implements partial action by including only the essential power management information fields in the beacon frame - specifically the maximum transmit power values for different channels. The information element structure includes only the necessary fields (element ID, length, and power value fields) without redundant data, allowing stations to quickly extract the critical power level information without processing excessive data.
Data Source
AI summary
A method for transmitting and receiving, by a station, channel information in a wireless LAN system, the method comprising:receiving a beacon frame including the channel information, wherein the channel information includes information for a channel change, the information for the channel change includes a field for a operating class of a new channel, a field for a channel number of the new channel and a field for a maximum transmit power of the new channel; parsing the beacon frame; and changing to a new channel with the maximum transmit power.