wifi roaming scenario

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AGENDA WiFi and Roaming: basic concepts. WiFi Roaming: an opportunity and a need. How to roam?

Ericsson Internal | 2012-03-27 | Page 2

Wi-Fi and Roaming: basic concepts The Wi-Fi is a wireless network technology which enables to create local wireless networks. Wi-Fi is created on standard IEEE 802.11 and is a local area network that uses high frequency radio signals to transmit and receive data over distances of a few hundred feet; uses Ethernet protocol. Wi-Fi permits to establish connections between computers, high-rate connections, by two modes: Infrastructure and Ad-Hoc.

Ericsson Internal | 2012-03-27 | Page 3

WLAN ArchitectureAd Hoc Mode Ad-Hoc mode: Peer-to-peer setup where clients can connect to each other directly. Generally not used for business networks.

Ericsson Internal | 2012-03-27 | Page 4

Ad Hoc Structure Mobile stations communicate to each other directly. Its set up for a special purpose and for a short period of time. For example, the participants of a meeting in a conference room may create an ad hoc network at the beginning of the meeting and dissolve it when the meeting ends.

Ericsson Internal | 2012-03-27 | Page 5

Infrastructure Mode

To Wired Network

Ericsson Internal | 2012-03-27 | Page 6

Infrastructure network There is an Access Point (AP), which becomes the hub of a star topology. Any communication has to go through AP. If a Mobile Station (MS), like a computer, a PDA, or a phone, wants to communicate with another MS, it needs to send the information to AP first, then AP sends it to the destination MS

Multiple APs can be connected together and handle a large number of clients. Used by the majority of WLANs in homes and businesses.Ericsson Internal | 2012-03-27 | Page 7

ESTABLISHING CONNECTION TO AN ACCESS POINT Both modes need following information to function: the Service Set Information (SSID), the channel, the data encryption method, a password. The connection between station-access point is done through two phases: Authentication, where the station willing to enter Wi-Fi network has to authenticate itself Association

After Authentication, the station is associated and can broadcast on the network. The access point, on his turn, will relay those information to the aimed receivers.Ericsson Internal | 2012-03-27 | Page 8

What is Roaming ? The roaming is a technology which enables a station to change his Access Point, internationally, while remaining connected to the network. To accomplish this, operators have to conclude Roaming agreement with foreign operators. For instance, if you come from South Africa to England, you will be able to keep your South Africas number if and if only your South African operator conclude a Roaming contract with an England operator in the area you are.

Ericsson Internal | 2012-03-27 | Page 9

agenda WiFi and Roaming: basic concepts. WiFi Roaming: an opportunity and a need. How to roam?

Ericsson Internal | 2012-03-27 | Page 10

First Opportunity: Revenues through In-RomingYou are a WISP(wireless internet service provider), operating one or several hotspots.

How to Improve your Revenue? Allow Customers of various providers to use your Hotspots through WiFi Roaming agreementsRoaming partner A Roaming partner B Roaming partner C

You are a WISPhotspot hotspot

At the hotelEricsson Internal | 2012-03-27 | Page 11

At the airport

Second Opportunity: Revenues through Out-RomingYou are a Provider, typically an ISP or Mobile operator. How to Improve your Revenue and ARPU? Allow your Customers to use Hotspots of various WISPs through WiFi Roaming agreementsYou are a Provider










Ericsson Internal | 2012-03-27 | Page 12

Wi-Fi Roaming: A Need Hotspot operators (WISPs) need customers to use their Hotspots! ISPs and Mobile Operators need Hotspots for their customers! No one has a worldwide coverage for WiFi There is a need for international WiFi Roaming This is similar to the GSM Roaming concept.

Most countries are not monopolistic for WiFi There is also a need for in-country WiFi Roaming This is different from GSM Roaming concept.

Ericsson Internal | 2012-03-27 | Page 13

agenda WiFi and Roaming: basic concepts. WiFi Roaming: an opportunity and a need. How to roam?

Ericsson Internal | 2012-03-27 | Page 14

Roaming Implementation in Wi-Fi How WiFi roaming works The roaming is not integrated to Wi-Fi, even if Wi-Fi is a wireless network. Contrarily to GSM, Wi-Fi didnt introduce the notion of itinerancy, which justify roaming absence in the standard IEEE 802.11. But today, with the cheapness and the benefits of wireless networks, most companies have the will to use Wi-Fi in all their premises. And they need to pass from an AP to another, while remaining connected. The protocol used to implement roaming in Wi-Fi is Inter Access Point Protocol (IAP) which needs a distribution system to broadcast information between Access Points. With standard 802-11 F, the station is re-associated, instead of associated during the connection on a new Access Point. Also, the Access Point have to monitor continuously access to the distribution system.Ericsson Internal | 2012-03-27 | Page 15

How WiFi roaming works? In the Standard 802-11 F, the station chooses the Access Point it wants to connect on and it operates like this: A station arrival in the association of areas covered by many Access Points Moving of a station in the association of areas covered by many Access Points Card notification requirement.

Functions that enable the three exchanges seen above are request, confirm, indication, response. The first function, request, corresponds to a station arrival in the association of areas covered by many Access Points. Confirm indicates if the function request ends correctly. An Access Point sends a function indication after a request to signal his association with the station aimed. the function response by which the old Access Point send to the new Access Point all the network information about the aimed station.Ericsson Internal | 2012-03-27 | Page 16

Inter-Access Point Protocol IEEE 802.11F or Inter-Access Point Protocol is a recommendation that describes an optional extension to IEEE 802.11 that provides wireless access point communications among multivendor systems. The IEEE 802.11 standard doesn't specify the communications between access points in order to support users roaming from one access point to another and load balancing. The protocol is designed for the enforcement of unique association throughout an Extended Service Set and for secure exchange of station's security context between the current Access Point (AP) and the new AP during the handoff period.

Ericsson Internal | 2012-03-27 | Page 17

extended service set An extended service set (ESS) is a set of one or more interconnected BSSs and integrated local area networks that appear as a single BSS to the logical link control layer at any station associated with one of those BSSs. The set of interconnected BSSs must have a common service set identifier (SSID).

Ericsson Internal | 2012-03-27 | Page 18

How to Roam: First Possibility Negotiate Multiple Bilateral Agreements for Roaming100 players means nearly 5000 connections ! WISP ISP WISP Mobile




Ericsson Internal | 2012-03-27 | Page 19

How to Roam: Second Possibility Use a Single Clearing-House for Multiple Roaming PossibilitiesISP WISP ISP Mobile WISP Mobile

Clearing-House solution


ISP Mobile ISP


Ericsson Internal | 2012-03-27 | Page 20

How to Roam? Clearing-House Solutions for Wi-Fi Roaming are used to reach many players (WISPs and/or Providers) through one agreement. Easy and cheap! Only one agreement is necessary, and the solutions on the market provide billing, clearing, etc.

Bilateral Wi-Fi agreements for Wi-Fi roaming are in general used for strategic partnerships. For example large European Mobile operators are signing bilateral agreements for Wi-Fi Roaming.

Ericsson Internal | 2012-03-27 | Page 21

references http://en.wikipedia.org/wiki/Wireless_LAN http://en.wikipedia.org/wiki/Service_set_802.11_network www.wirlab.net/wirlab_wlan_roaming.ppt http://en.wikipedia.org/wiki/Roaming http://www.wifinotes.com/how-wifi-roaming-works.html http://en.wikipedia.org/wiki/Service_set_802.11_network

Ericsson Internal | 2012-03-27 | Page 22


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