WLAN-Based Assistance for Roaming Between Heterogeneous Networks Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 WLAN-Based Assistance for Roaming Between Heterogeneous Networks Date: 2006-11-13 Authors: Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <stuart.kerry@philips.com> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <patcom@ieee.org>. Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Abstract This proposal describes assistance provided by an AP to a multi-radio terminal to aid in knowing when to roam to and from an 802.11 WLAN. This assistance is provided in the form of topology and PHY information and is orthogonal to network selection. There will be a straw poll at the end of this presentation. Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Example: when should handset roam off Cellular network and onto WLAN network? AP#1 Egress AP One answer: when client device observes minimum RSSI needed to associate with Egress AP. Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

What is helpful information for Multi-Radio Client Device? Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 What is helpful information for Multi-Radio Client Device? It is helpful for client device to know whether AP is indoors or outdoors Indoors: Client doesn’t want to transition onto 802.11 WLAN too soon There may be limited cellular (or other non-802.11 network) coverage indoors Outdoors: Client devices can decide to turn on (or leave on) cellular (or other non-802.11) radio when outdoors Some devices, for example, can take up to 30s to register onto a cellular network, so advance warning that user is moving outdoors can be helpful in preserving call during roam to cellular Outdoor device speed can be vehicular (say up to 100km/hr)—not all STA 802.11 PHYs may be able to support vehicular speeds (e.g., in municipal Mesh network) Once device is outdoors, it can leave 802.11 coverage area much faster than indoors so it may have to roam onto non-802.11 network more quickly When is it safe to roam onto WLAN? At higher 802.11 RSSI levels there is typically lower chance for ping-ponging between heterogeneous networks. It’s more likely client device is actually inside the building (rather than outside the door). Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

What is helpful information for Multi-Radio Client Device? (cont.) Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 What is helpful information for Multi-Radio Client Device? (cont.) When is it safe to turn off non-802.11 radio when inside building? Example choice: after client device has roamed onto WLAN at egress AP and after transitioning to AP in next inside ring When is it important to turn non-802.11 radio back on when moving from inside building to outside? In enough time to register onto the non-802.11 network such that an ongoing call is not dropped Example choice: turn on non-802.11 radio upon transition to Egress AP after having been associated to interior AP Is their outdoor 802.11 coverage? If client receives 802.11 neighbor reports indicating outdoor coverage, client may decide to remain on 802.11 network longer Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Roaming Assistance Information Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Roaming Assistance Information Egress bit: 1 = AP is an egress AP, 0 = AP is not egress AP AP cannot be an Egress AP if it is outdoors Indoor bit: 1 = AP is indoors Border bits (2): 0x0 = AP is 1 ring removed from Egress AP; 0x1 = AP is 2 rings removed from Egress AP ; 0x2 = AP is 3 rings removed from Egress AP ; 0x3 = AP is 4 or more rings removed from Egress AP etc. Border bits shall be set to zero when AP is an Egress AP. 0 = AP is outdoors Border bits (2): 0x0 = AP is at edge of coverage area; 0x1 = AP is one ring removed from edge of coverage; 0x2 = AP is two rings removed from edge of coverage; 0x3 = AP is 3 or more rings removed from edge of coverage. Minimum RSSI to Associate (8 bits): signed integer in units of dBm which provides minimum RSSI required to be measured at non-AP STA in order to associate (e.g., -75dBm) This information should also be added to TGk neighbor report element Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Roaming Assistance IE B0 B1 B2 B3 B4 B7 Element ID Length Indoor AP Egress AP Border Bits Reserved Min RSSI Bits: 8 1 2 4 Octets: Roaming Assistance IE is included in Beacons and Probe Response frames If the IE is included in Beacons and Probe Responses, then all fields shall be configured This IE is optional Roaming Assistance IE fields defined on preceding slide Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Roaming Assistance Sub-element Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Roaming Assistance Sub-element B0 B1 B2 B3 B4 B7 Sub-Element ID Length Indoor AP Egress AP Border Bits Reserved Min RSSI Bits: 8 1 2 4 Octets: Roaming Assistance Sub-element is included in TGk Neighbor Report element If the sub-element is included in Neighbor Report elements, then all fields shall be configured This sub-element is optional Roaming Assistance Sub-element fields defined on preceding slide Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Proposal Benefits Provides roaming aids to a multi-radio terminal to aid in robust inter-network roaming Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Feedback? November 2006 Month Year doc.: IEEE 802.11-yy/xxxxr0 Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 November 2006 Straw Poll Is Task Group U supportive of 11-06/1848r0 and interested in having author draft normative text for inclusion into TGu draft? Dave Stephenson et al, Cisco Systems, Inc. John Doe, Some Company