1. Considerations about Network Selection
Month 2000
doc.: IEEE /xxx
July 2004
Considerations about Network Selection
Eleanor Hepworth, Siemens Roke Manor
Stefan Berg, Siemens
Wolfgang Gröting, Siemens
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

2. Month 2000
doc.: IEEE /xxx
July 2004
What’s the Problem?
Need to provide the terminal with information to choose the appropriate network
In general, at different times (while attaching to a network) the information can be provided
Pre-association
Post-association/pre-authentication
Post-authentication
NOW
Let‘s focus on ‚pre-association’ and…
…have a closer look on the information itself
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

3. A user scenario – without network advertisements
July 2004
A user scenario – without network advertisements
Hotspot #1
Internet
No Real time
support
4. Start VoIP session
2. Start VoIP Application AP
1. Advertise Network identifier
User
6.Stop VoIP session
Hotspot #2
Real Time
support
2. Advertise Network identifier
3. Connect to Hotspot #1
(wild guess)
5. User unsatisfied with Quality
7. Re-Start VoIP session AP
Eleanor Hepworth, Siemens Roke Manor

4. A user scenario – with network advertisements (e.g. QoS)
July 2004
A user scenario – with network advertisements (e.g. QoS)
Hotspot #1
No Real time
support
Internet
2. Start VoIP Application AP
1. Advertise Network identifier,
no real time support
User
Hotspot #2
1. Advertise Network identifier
Real Time
support
5.Start VoIP session
with real time support
3. Evaluate application
requirements & user preferences
4. Chose Hotspot #2, since its support real time services
6.  User … AP
 Better user experience, reduced application delay, reduced signalling over the air
Eleanor Hepworth, Siemens Roke Manor

5. What Information would be useful?
Month 2000
doc.: IEEE /xxx
July 2004
What Information would be useful?
Network Identification
Roaming Agreements
Costs for Network Usage
Authentication Mechanisms
E2E QoS / Bearer Service
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

6. Only Network Identification or even more?
Month 2000
doc.: IEEE /xxx
July 2004
Only Network Identification or even more?
Mandatory for network identification purpose
Pre-association; beacon and/or probe
Current Practice:
The SSID is used to advertise the network identity
Data-Format SSID: 32byte
But:
Which identity needs to be advertised?
Can other network characteristics be derived from the identifier?
A structured SSID namespace could provide additional information and support network selection e.g. this is a public or private hotspot, 3GPP interworking/roaming capabilities, etc
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

7. What about Roaming Agreements?
Month 2000
doc.: IEEE /xxx
July 2004
What about Roaming Agreements?
Mandatory for authentication purpose
Reasonably pre-association; beacon and/or probe
Motivation: Indicate all supported roaming partners
STA impact: new mechanism to transfer and evaluate the information
Amount of data: 10s or 100s of bytes
Assuming 10 roaming partners example data formats could be:
ASCII coded NAI-realms
ITU-T E.212 mobile country codes
36bytes * 10 = 360bytes
3bytes * 10 = 30bytes
e.g. vodafone.com, t-mobile.com NAI max. 72byte (RFC2486)
e.g = T-Mobile Germany Needs administration + conversion
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

8. Do we need Charging Information?
Month 2000
doc.: IEEE /xxx
July 2004
Do we need Charging Information?
Optional, it’s nice to know about the cost of using the network
Preferably pre-association; beacon and/or probe
STA impact: new mechanism to transfer and evaluate the information
Many, many options; could be a large list with quite an amount of data
Amount of data: 10s or 100s of bytes
Example data formats for AP and 10 roaming partners:
Extended set of charging information: currency, type, amount, units, formats, …
Reduced set of 4 charging classes and 4 different charging modes (data, time, service, flat)
44bytes * 11 = 440bytes
1bytes * 11 = 11bytes
Detailed charging information
Only a vague hint on costs
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

9. What about Authentication Mechanisms and new user signup services?
Month 2000
doc.: IEEE /xxx
July 2004
What about Authentication Mechanisms and new user signup services?
Mandatory for authentication purposes and helpful for new user signup support
Preferably pre-association; beacon and/or probe
WPA/802.1X is already advertised: privacy bit is set or not
In case of UAM: indication needed on subscriber selection support
STA impact: new mechanism to transfer and evaluate the information
Amount of data: 10s of bytes
Example data formats for AP and 10 roaming partners:
Indication of new user registration possibility
Additional information, payment methods, authentication method
1bit * 11 = 11bit
2bytes * 11 = 22bytes
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

10. What about end-2-end QoS?
Month 2000
doc.: IEEE /xxx
July 2004
What about end-2-end QoS?
Optional for bearer service selection
Pre-association; beacon and/or probe
Motivation:
802.11e realizes only over the air QoS
Provide a hint on network capabilities (QoS classes)
Provide information on supported QoS mechanisms
STA impact: new mechanism to transfer and evaluate the information
Amount of data: 10s of bytes
Example data formats for AP and 10 roaming partners:
4 different QoS classes (e.g. 3GPP: conversational, streaming, interactive, background)
Additional information on 4 different QoS mechanisms
4bit * 11 = 44bit
1byte * 11 = 11byte
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company

11. Conclusions and Proposal
Month 2000
doc.: IEEE /xxx
July 2004
Conclusions and Proposal
Mandatory information and its characteristics have been identified
Proposal:
Use the information outline here in establishing formal requirements for network selection and …
… identify, what is feasible to advertise pre-association
Questions:
Are there any other things that people feel should be included?
Eleanor Hepworth, Siemens Roke Manor
John Doe, His Company