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A Periodic 5 MHz Measurement Pilot for Channel Scan. Authors:. Date: 2010-05-11. Problem Description. Large initial access delay of passive channel scanning is a problem for dot11 devices in TVWS. The problem comes from combinations of many channels (30) and 3 different bandwidth.
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A Periodic 5 MHz Measurement Pilot for Channel Scan Authors: Date: 2010-05-11
Problem Description • Large initial access delay of passive channel scanning is a problem for dot11 devices in TVWS. • The problem comes from combinations of many channels (30) and 3 different bandwidth. • Scanning time might be around 9,000 ms [2] relying on beacon frames.
Proposed Solution • The Measurement Pilot frame defined in dot11k [1] which contains a subset of the information provided in a Beacon frame is used to assist a STA for scanning. • The Measurement Pilot frame has a small interval relative to a Beacon interval which can reduce scanning time. • A STA in TVWS still need to try combinations of various bandwidths. • We propose to let an AP periodically transmit a 5 MHz Measurement Pilot frame in one of the channels used e.g., the lowest channel, for systems using more than 1 channel.
Measurement Pilot Frame Format • Use a different action field value (8), to indicate that it is a 5 MHz Measurement Pilot frame, so that the mismatch of channel bandwidth (10 MHz, 20 MHz) and 5 MHz will not cause a problem. Public Action field values
Conclusions • An AP transmits 5 MHz Measurement Pilot frames periodically in one of the channels used can greatly reduce the scanning time and complexity of passive scanning process. • Based on the received information contained in a 5 MHz Measurement Pilot frame, a STA can tune to the right bandwidth and join the network.
References • IEEE Standard, "IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 1: Radio Resource Measurement of Wireless LANs," IEEE, New York, NY, June 2008. • E. Kim, Y. Seok and S. Park, “IEEE document, doc.: IEEE 802.11-10/0263-r1,” March 2010.