White Space Map Channel Scanning in Wireless LANs
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Solution Overview
Problem
In wireless local area networks (WLANs) operating in TV white spaces, existing channel scanning methods face challenges in scalability and coexistence with other wireless communication systems, leading to increased overhead and power consumption, especially when a large number of channels need to be scanned.
Innovation Solution
A channel scanning mechanism that uses a white space map to identify occupied channels by incumbent users, allowing stations to selectively scan only unoccupied channels, reducing scanning time and power consumption while maintaining detection probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of channels are scanned to ensure detection of incumbent users, then detection probability is improved, but power consumption and overhead increase
Solution Approach 1:
The access point performs preliminary channel scanning and spectrum sensing before stations perform their own scanning. The AP collects channel availability information and includes it in beacon frames, allowing stations to skip scanning already-scaned channels. This preliminary action by the AP reduces the total scanning burden on stations while maintaining detection probability.
Solution Approach 2:
The channel scanning task is segmented between the access point and stations. The AP handles the spectrum sensing and channel availability detection, while stations rely on the AP-provided information. This segmentation allows the system to maintain high detection probability through AP's sensing while reducing station power consumption by eliminating redundant scanning.
2Reliability
If traditional channel scanning is performed by each station independently, then detection probability is maintained, but overhead and power consumption increase
Solution Approach 1:
Multiple stations' scanning operations are merged into a single centralized scanning operation performed by the access point. The AP performs spectrum sensing and channel scanning on behalf of all associated stations, combining their scanning needs into one unified process. This reduces total scanning time while maintaining detection probability through the AP's comprehensive channel assessment.
Solution Approach 2:
The access point performs preliminary channel scanning and spectrum sensing before stations perform their own scanning. The AP collects channel availability information and includes it in beacon frames, allowing stations to skip scanning already-scaned channels. This preliminary action by the AP reduces the total scanning burden on stations while maintaining detection probability.
3Reliability
If IEEE 802.11 DCF and EDCA protocols are applied in TV white space environment, then Quality of Service is ensured, but scalability deteriorates
Solution Approach 1:
The channel access function is segmented between the access point and stations. The AP performs centralized spectrum sensing and channel scanning, while stations use the provided information for their transmissions. This segmentation reduces the complexity of medium access control for individual stations, improving scalability while the AP maintains QoS through centralized coordination of channel access.
Solution Approach 2:
The access point acts as an intermediary between stations and the TV white space spectrum. Instead of stations directly competing for channel access using DCF/EDCA, the AP mediates by performing spectrum sensing and providing channel availability information. This intermediary role simplifies station operations and improves scalability while maintaining QoS through AP-controlled channel access.
Data Source
AI summary
A method and apparatus of scanning channels of a white space zone in a wireless local area network is provided. A beacon frame includes a white space map including information about whether each white space channel in the white space zone is occupied by an incumbent user. Channels of the white space zone are scanned based on the white space map.