The Network Beacon Announcement scanning method November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 The Network Beacon Announcement scanning method Dirk Kuijsten University of Amsterdam Dirk.Kuijsten@student.uva.nl Prof.dr. R.J. Meijer, UvA, TNO Telecom rmeijer@science.uva.nl D. Kuijsten, University of Amsterdam John Doe, His Company

Outline Introduction Network Beacon Announcement Time synchronization November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Outline Introduction Network Beacon Announcement Time synchronization Results Analysis Conclusion Questions D. Kuijsten, University of Amsterdam John Doe, His Company

Introduction Current method’s disadvantages: Non-directed search November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Introduction Current method’s disadvantages: Non-directed search STA Probe request: power intensive Probe request medium access: Interruption by client data transmissions Not determined D. Kuijsten, University of Amsterdam John Doe, His Company

Network Beacon Announcement November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Network Beacon Announcement Current AP requests Beacons on other APs AP transmits information to STA Channel, other AP MAC address, Beacon time Client performs passive scan Beacon transmission time within a error margin defined by the time sync accuracy between the APs D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

Time synchronization Only between APs November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Time synchronization Only between APs Using NTP: <1ms possible on LAN networks Or use external time source Common backbone networks CDMA / UMTS / Wi-Max GPS, radio D. Kuijsten, University of Amsterdam John Doe, His Company

Results Reference implementation works on Linux November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Results Reference implementation works on Linux Scanning speed of around 5 ms Possible speeds of 1 ms measured D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Analysis - Advantages Simultaneous STA scans possible if AP sends NBA info in broadcast Embed STA MAC in info to require STA to start scan Other STAs are free to start scan Passive scan Other APs can use QoS to reserve the beacon frame transmission in advance: transmit time guaranteed Old AP can know client state: buffer frames, IAPP proactive caching, pre-keying D. Kuijsten, University of Amsterdam John Doe, His Company

Analysis - Disadvantages November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Analysis - Disadvantages More complex Extra requirements for wired network Simultaneous STA scans: for STAs that are free to start a scan: scanning/idle state unknown STA can miss beacon if time sync error is large; time range could be defined dynamically STA connection required before start scan D. Kuijsten, University of Amsterdam John Doe, His Company

Analysis - Usage model Voice Over WLAN usage models needed November 2004 Analysis - Usage model Voice Over WLAN usage models needed Simulation of multiple handoffs: 2 VOIP calls moving through the network Performance of Network Beacon Announcement scan vs. other methods: Loss of signal detection Scanning speed Overall higher layer latency Number of lost packets D. Kuijsten, University of Amsterdam

Conclusion Fastest scan possible Power efficient Simultaneous scans November 2004 doc.: IEEE 802.11-02/1380r0 November 2004 Conclusion Fastest scan possible Power efficient Simultaneous scans Network management with more client scans Works on current hardware Can be improved with new firmware Can be improved with dedicated timing hardware (from external time sources) D. Kuijsten, University of Amsterdam John Doe, His Company

November 2004 Questions? D. Kuijsten, University of Amsterdam