White Space Map Element for WLAN Channel Discovery
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Solution Overview
Problem
In wireless local area networks (WLANs), unlicensed devices operating in TV White Spaces face challenges in efficiently finding available channels, protecting incumbent users, and reducing scanning time and power consumption, especially when accessing regulatory databases for channel information.
Innovation Solution
A method and apparatus for transmitting a White Space Map (WSM) from an enabling station to a dependent station, using a beacon frame, probe response frame, or white space map announcement frame, which includes a channel number field and maximum power level field, allowing the dependent station to operate within identified available channels, thereby reducing scanning time and protecting incumbent users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unlicensed devices perform spectrum sensing to identify available channels in TV White Spaces, then they can protect incumbent users, but scanning time and power consumption increase
Solution Approach 1:
The patent applies preliminary action by having the enabling station perform spectrum sensing and generate the White Space Map in advance. The WSM contains pre-identified available channels and their characteristics, which are then transmitted to dependent stations. This allows dependent stations to immediately know which channels are available without performing their own time-consuming spectrum sensing, thus resolving the contradiction between protecting incumbent users and reducing scanning time.
Solution Approach 2:
The patent introduces the White Space Map as an intermediary information structure that mediates between the enabling station's spectrum sensing results and the dependent stations' channel selection needs. The WSM acts as a pre-processed database that contains channel availability information, maximum power levels, and other relevant data, allowing dependent stations to make informed decisions without direct spectrum sensing, thereby reducing their scanning time while maintaining incumbent user protection.
2Adaptability or versatility
If unlicensed devices perform spectrum sensing to identify available channels, then they can operate in TV White Spaces, but power consumption increases
Solution Approach 1:
The enabling station performs spectrum sensing and channel identification in advance, storing results in the White Space Map. Dependent stations receive this pre-processed information and can immediately determine available channels without performing their own spectrum sensing operations. This eliminates the need for continuous or initial spectrum sensing at dependent stations, significantly reducing their power consumption while maintaining the ability to operate in TV White Spaces.
Solution Approach 2:
The enabling station serves the dependent stations by providing them with ready-made channel availability information through the WSM. Instead of each dependent station independently performing spectrum sensing (self-service in the traditional sense), they receive service from the enabling station that has already performed the sensing and processed the information, reducing overall network power consumption.
3Loss of information
If unlicensed devices scan all channels to find available channels, then they can ensure complete channel information, but scanning time and complexity increase
Solution Approach 1:
The patent extracts only the relevant channel availability information from the complete spectrum and concentrates it in the White Space Map. Instead of requiring dependent stations to scan all possible channels, the WSM extracts and presents only the channels that are actually available for use, along with their maximum power levels and other relevant parameters. This extraction approach ensures complete and accurate channel information is provided while dramatically reducing scanning time.
4Measurement precision
If unlicensed devices access regulatory databases to obtain channel information, then they can acquire accurate available channel lists, but device complexity and operational difficulty increase
Solution Approach 1:
The enabling station acts as an intermediary that handles regulatory database access on behalf of dependent stations. The enabling station queries the regulatory database, processes the information into the WSM format, and distributes it to dependent stations. This eliminates the need for dependent stations to have direct database access capabilities, reducing their complexity while maintaining accurate channel information through the intermediary's processing.
Data Source
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AI summary
A method and an apparatus transmitting and receiving a White Space Map information between two stations in a wireless local area network system are disclosed. For transmitting a white space map information from a first station to a second station in a regulatory domain where a licensed device and an unlicensed device are permitted to operate in a wireless local area network (WLAN), the method comprises: obtaining, at the first station, a list of available channels with a first channel granularity and maximum allowed transmission powers of the available channels from a regulatory database; and transmitting, from the first station, one of a beacon frame, a probe response frame and a white space map announcement frame comprising a white space map (WSM) element to the second station such that the second station operates as the unlicensed device using one or more channels having a second channel granularity and located only within the available channels identified by the WSM element, wherein the WSM element comprises a channel number field and a maximum power level field, wherein the channel number field indicates the list of available channels with the first channel granularity and the maximum power level field indicates maximum allowed transmission powers of the available channels.