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From: stds-802-21@ieee.org [mailto:stds-802-21@ieee.org] On Behalf Of Liang Chen
Sent: Monday, November 07, 2005 2:58 AM
To: STDS-802-21@listserv.ieee.org
Subject: Questions on the network detection
Dear all,
802.21/D00.01 draft describes an mechanism for the vertical handover decision in Sec. 6.3. With the help of networking location information boardcast in any medium supported by 802.21, STA could aware the surrounding networks before handover. However, I guess there are some problems in the real scenarios.
1. Due to the cheap deployment cost of 802.11 AP, users may want to deploy the 802.11 hot-spot in their office or home independently and without the notification to the WWAN operators. When a user moves to their home/office from outsides, how user's STA know there is a 802.21 supporting WiFi AP from the location information boardcast by WWAN.
[Vivek G Gupta]
You are right!
WiFi is a network operating in unlicensed band and there can be many ad hoc unmanaged installations.
It's going to be quite challenging (almost impossible) to cover all of these installations through the Information service.
However in cases of more more managed WiFi installations, a multi-network operator, or a multi-network IT administrator in an enterprise may be able to provide more reliable and up to date information about public hot-spots and in general more managed WiFi installations…ones that provide more compelling services with certain degree of reliability etc. The user in such cases could get updates from network operator through other wider coverage area radios and take advantage of more opportunistic handovers to networks such as WiFi. Over a period of time the service could cover a large number of such managed installations and some of the other ones as well. For ad hoc unmanaged WiFi installations that are not covered by this service the user may still have to resort to traditional probe/scan and discover type access network specific mechanisms.
Do you still see such a service being useful?
2. How STA locates itself in the wireless networks map? GPS may not work in-door and increase the cost.
[Vivek G Gupta]
Yes this service does rely on location information, but believe there are several ways of tackling this even indoors.
Also emerging devices are starting to incorporate and take advantage of "presence" in many different ways.
Moreover, I am a little confused on the different benefits of network-initiated and MN-initiated handover mentioned in Set. 5.2.
[Vivek G Gupta]
WiMax and Cellular networks support network initiated handovers wherein the network operator may influence network selection due to a variety of reasons in a multi-radio environment. 802.21 handover mechanisms support co-operation between client devices and network in promoting the selection of the most appropriate network at different times.
Best regards,
-Liang Chen