1. January 2005Rudolf, Kwak, Worstell1 VoIP in 802.11 WLANs and E911 support Marian Rudolf, Joe Kwak, InterDigital; Harry Worstell, AT&T doc: IEEE 802.11-05/0014r0

2. January 2005 Submission Rudolf, Kwak, Worstell 2 Contents Background VoIP and mobility in WLANs Regulatory issues Technical issues Summary

3. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 3 Background (1) Emergency call support is a requirement and a reality today for PSTN E 911 has been a considerable issue in the cellular industry for the several past years, but can be considered more or less solved today For example, Phase II location accuracy and reliability Network-based solutions: 100 meters for 67 percent of calls, 300 meters for 95 percent of calls; Handset-based solutions: 50 meters for 67 percent of calls, 150 meters for 95 percent of calls. In the case of E 911 support for VoIP services challenges still remain

4. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 4 Background (2) Today, even “fixed” VoIP phone service offerings for the residential market are limited for supporting E 911 Number location information can not always be tracked by dispatcher in PSAP, call back is not always possible, address registration may be required upon purchase of the equipment When the VoIP phone is moved to a new location, the 911 call will still be sent to the location of the registered address The registered address can be changed in principle, but delays are at least in the order of days / weeks Things get worse with more mobility as enabled by VoIP phones using WLANs WLAN-based VoIP phones can work anywhere and the user can be expected to roam seamlessly Office environment, Home, Public hotspots,…

5. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 5 VoIP and mobility in WLANs PSTN E911 Centre Local Emergency Response Operations Center PSTN Internet Direct Line Connection Home WLAN AP VoIP provider ITX Campus WLAN or Public WLAN Hotspots or Enterprise WLAN AP (3) Emergency response will always be sent to place of registry ! (1) Fixed, “hard-coded” location where VoIP WLAN handset is registered (2) Point of origin for issued emergency call

6. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 6 Regulatory issues VoIP is being evaluated by FCC and state regulatory committees to determine new requirements A special case are VoIP handsets over 802.11, more complicated than their “fixed VoIP” counterparts due to mobility When FCC imposes E 911 requirements on VoIP over WLAN, present day technical hurdles could suffocate VoIP market Even worse, if state legislators impose individual E 911 requirements, this would create a patchwork of fractured policies per state

7. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 7 Technical issues for Mobile VoIP(1) Force VoIP users to manually update their location? Becomes very quickly unpractical if user moves between too many locations or often to new locations Currently, update cycles of PSAP are slow (~1 day) Certain users will not manually update location Modify network protocols to automatically update user location ? Network management protocols (802.1x, DHCP and SNMP) may be an alternative, but extent of support in existing 802.11 standards is limited Still, update cycles of PSAP are a problem (~1 day)

8. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 8 Technical issues for Mobile VoIP(2) Cellular / WLAN dual-mode handsets are a special case Fallback on cellular for E 911 is an option 802.11 specific issues extend beyond the wired network: Admission: Tightly managed WLANs may actually prevent emergency callers from establishing a 911 call if it is not authorized to enter the network Radio Access: No priorities for emergency calls currently exist in 802.11 standards, even with WME / 11e AP location: currently unknown to network in non-proprietary manner, even if AP-id based may easily prove sufficient Caller location: Mapping STA-->AP-->location currently not possible in non-proprietary manner. Management interfaces (MIBs) insufficient

9. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 9 Lessons Learned from Cellular E911 Waiting till regulations are imposed can be very costly for infrastructure stakeholders: Retrofits are the worst way to proceed. Simple MIB, L1 and L2 “hooks” for STA location will permit higher layer applications to address the regulation details later by software upgrade to network, not STAs. It is prudent and cost effective to implement location management in WNM NOW. Similar to cellular, there are business opportunities related to location awareness which may also evolve soon after location hooks are implemented in 80211, e.g. ads for nearby business, local weather/traffic, proximity messaging, and other location -based services.

10. doc: IEEE 802.11-05/0014r0January 2005 Submission Rudolf, Kwak, Worstell 10 Summary VoIP over WLAN is one of the most promising use cases for 802.11 technology in the market Both “fixed” (residential, office) VoIP handsets and “roaming” (WLAN) VoIP handsets have the same kind of problem regarding connectivity to and updating PSAP on the network side Mobile handsets pose additional problems for VoIP with 802.11 Full support for E 911 VoIP with 802.11 extends beyond the wired network: admission, access, mobile location awareness, etc How to address the eventual regulatory requirements for VoIP in 802.11 networks is undefined and could limit and delay the WLAN VoIP market. We should begin to address these location management problems in WNM (new TGv).