magazine 文章心得

Magazine文章心得

學號： 643430007姓名：蘇彥文

Abstract

1) A new method to support UMTS WLAN vertical handover using SCTP

2) Interworking techniques and architectures for WLAN 3G integration toward 4G mobile data networks

3) IEEE802.11 roaming and authentication in wireless LAN cellular mobile networks

4) 心得

Magazine 1

A new method to support UMTS WLAN vertical handover using SCTP

Note Abstract

UMTS networks and WLANs Third-generation cellular networks UMTS/WLAN vertical handover proble

m Overview of Mobile SCTP VERTICAL HANDOVER PROCEDURES

UMTS networks and WLANs UMTS

•wide-area connectivity •low data rate • high mobility

WLANs•higher data rate •low mobility

Third-generation cellular networks

Both UMTS and WLANs•WLAN offer higher bandwidth •Mobile users accessing the Internet via UMT

S/WLAN are free to move•Handover between UMTS and WLANs

•MIP from IETF •provides transparent support for host mobility •routing architecture of mobile host

•Difficult to maintain the continuity between UMTS and WLAN •Point of this article

UMTS/WLAN vertical handover problem

UMTS/WLAN verti cal handover support via two types of SCTP • single-homing asymmetric config uration •dual-homing symmetric configu ration

Inte grated UMTS/WLAN network architecture • tightly coupled solutions ： connect UMTS and WLAN• loose coupling solutions ： separate out UMTS and W

LAN• loose coupling offers several advantages over tight co

upling

Overview of Mobile SCTP (1)

Originally for VoIP of 3GPP Reliability Multi-homing

•established over multiple interfaces identified by multiple IP addresses

•An SCTP association between two hosts, say, A and B, is defined as •{[a set of IP addresses at A] + [Port-A]} + {[a set of IP addresses at B] + [Port-B]}.


base version of SCTP cannot be used directly to support UMTS/ WLAN vertical handover

Fortunately, the recently proposed DAR extension for SCTP enables the endpoints to add, delete, or change the IP addresses during an active SCTP association using address configuration (ASCONF) messages.• basis of mSCTP


mSCTP•Using for supporting UMTS/WLAN vertical h

andover•capabilities to add, delete, and change the I

P addresses dynamically during an active SCTP association


mSCTP Protocol architecture

VERTICAL HANDOVER PROCEDURES (1)

FS can also be configured for: •Single-homing: The FS provides only one IP

address to support handover.

•Dual-homing: The FS allows more than one (usually two) IP addresses to support

Handover procedure has three basic steps: •Add IP address

•Vertical handover triggering

•Delete IP address


single-homing configuration


dual-homing configuration

SIMULATION RESULTS AND DISCUSSIONS (1)

use network simulator ns-2 to perform the simulations and obtain •set to be 384 kb/s for the UMTS link and

2 Mb/s for the WLAN link

•delay is set to 100 ms

•FTP traffic is started at the MC at time 1 s

•handover triggering process is acti vated at time 5 s


simulation results •UMTS-to-WLAN handover delay is 533 ms


simulation results•WLAN-to-UMTS delay is 513 ms


throughput performance for vertical handover in both directions

Magazine 2

Interworking techniques and architectures for WLAN 3G integration toward 4G mobile data networks

Note Abstract WLAN/3G inter working function INTERWORKING MODEL AND REQUIREMEN

TS NETWORK SELECTION INTERWORKING SCENARIOS 3G-Based Access Control and Charging

•REFERENCE POINTS Access to 3G Packet-Switched Services

•REFERENCE POINTS CONCLUSIONS

WLAN/3G inter working function WLAN/3G inter working techniques and

architectures can support•Authentication•Authorization•Accounting •WLAN sharing•Consis tent service provisioning

INTERWORKING MODEL AND REQUIREMENTS (1)

high-level WLAN/3G interworking model.

INTERWORKING MODEL AND REQUIREMENTS (2)

WLAN/3G interworking must• provide 3G-based authentication

• support 802.1X access control

• support the legacy UAM and open access control schemes

NETWORK SELECTION

MS needs to perform the following selection proce dures • Select a WLAN that supports interworking with 3G PL

MNs

• MS must select one of the PLMNs

several solutions of network selection problem • broadcast an SSID with a suitable format

• transmitting a probe request including a predefined well-known (3G-specific) SSID

INTERWORKING SCENARIOS (1) Scenario 1 — Common Billing and Customer Care Scenario 2 — 3G-Based Access Control and

Charging Scenario 3 — Access to 3G Packet-Switched

Services Scenario 4 — Access to 3G Packet-Switched-Based

Ser vices with Service Continuity Scenario 5 — Access to 3G Packet-Switched-Based

Ser vices with Seamless Service Continuity Scenario 6 — Access to 3G Circuit-Switched-Based

Ser vices with Seamless Mobility

INTERWORKING SCENARIOS (1)

3G-Based Access Control and Charging (1)

INTERWORKING ARCHITECTURE


AAA SIGNALING


AAA SIGNALING1) MS sends its identity to the WLAN within an EAP-Resp

onse/Identity mes sage• MS’s identity is NAI-1 • username@realm

2) WLAN discovers route AAA messages to the 3G PLMN corresponding to this realm

3) AAA access request is sent to the identified 3G PLMN over the Wr interface

4) WLAN sends network advertisement data to the MS • use a new EAP method called 3G-Info • XML structure

REFERENCE POINTS (1)

3G internal interfaces •Wr/Wb

•carries AAA signaling between the WLAN and the 3G / home PLMN in a secure manner

•Support Radius by acrossWr/Wb

•Ws/Wc •provides the same functionality as Wr/Wb but ru

ns between a 3G AAA proxy and a 3G AAA server


•Wf •transport charging information toward the 3G op

erator’s CGw/CCF located in the visited or home PLMN

•Wo •used by the 3G AAA server to communicate with t

he 3G OCS


•Wx •between the 3G AAA server and the HSS •used primarily for accessing the WLAN subscripti

on profiles of the users

•D/Gr •used for exchanging subscription information be

tween the 3G AAA server and the HLR by means of the MAP protocol

Access to 3G Packet-Switched Services (1)

INTERWORKING ARCHITECTURE


AAA SIGNALING


several additional interfaces Wn

•used for transporting tunneled user data between the WLAN and the WAG

Wm •located between the 3G AAA serv er and PDG •used to enable the 3G AAA server to retrieve

tunneling attributes and an MS’s IP configuration parameters from/via the PDG


Wi •provided via the Wi interface based on IP

Wg •used by the 3G AAA proxy to deliver routing

policy enforce ment information to the WAG Wp

•transports tunneled user data traffic between the WAG and the PDG

CONCLUSIONS

maintain access to the same 3G packet-switched services across several radio access technologies • such as IEEE 802.11, HiperLan/2,

UTRAN, and GERAN Ses sion mobility is an additional

requirement that needs further consideration and presents consid erable technical challenges

Magazine 3

IEEE802.11 roaming and authentication in wireless LAN cellular mobile networks

Note Abstract Integrate wireless LAN service IEEE 802.11 WIRELESS LAN ROAMING RADIUS PROXY IEEE 802.11 HORIZONTAL ROAMING MOBILE IP HANDOFF PERFORMANCE IMPROVEMENT WIRELESS TRANSMISSION PRIVACY SECURITY ANALYSIS AUTHENTICATION AND KEY NEGOTIATION DEMONSTR

ATION SUMMARY

Integrate wireless LAN service (1)


IEEE802.11 service integration functionality •integrate into cellular networks

Wireless network security Service quality

•refers to handoff speed and packet loss rate

IEEE 802.11 WIRELESS LAN ROAMING (1)

IEEE802.11 roaming structure is based on • AAA broker with a Remote Authentication Dial-In User

Service (RADIUS) server proxy

CA servers • are special servers that issue and verify certificates to

fixed nodes or net works upon request so that they have proofs to identify themselves

• are organized in a tree topology and working in a distributed way

IEEE 802.11 WIRELESS LAN ROAMING (2)

RADIUS PROXY

RADIUS server retrieves •remote server’s domain from the user’s r

equest •includes the network access identifier

•identifier@domain_name

IEEE 802.11 HORIZONTAL ROAMING (1)

Each network domain is interconnected by AAABs

In order to provide IP mobility • for eign agent (FA) is placed into the NAS

The architecture is able to process two hor izontal roaming scenarios •The current IEEE802.11 device connects to the netw

ork via the NAS •Seamless roaming

MOBILE IP HANDOFF PERFORMANCE IMPROVEMENT (1)

roam between a wireless LAN and a cellular network • routed to the mobile station through its HA

HA redi rects the data flow to the new IP address

For typical data applications is not necessary to use real-time seamless handoff

For real-time Internet applica tions like voice or streaming video ， handoff latency and packet loss performance have become more and more critical

MOBILE IP HANDOFF PERFORMANCE IMPROVEMENT (2)

In order to reduce the latency of Mobile IP handoff • used to assist Mobile IP handoff

• pre-registration and authentication data can be sent to the mobile station before it moves

• Additional flow control should be taken in the handover perio

WIRELESS TRANSMISSION PRIVACY (1) built-in WEP encryption cannot guaran te

e data transmission privacy User location updates are transparent to

the scheme since user mobility is handled in the network layer

FA just relays the authentication message between the mobile station and its home network

WIRELESS TRANSMISSION PRIVACY (2) Authenticating parties share a secret key

• stored in either the mobile station or its Subscriber Identity Mod ule (SIM) card

Authenticating parties do not share a secret key • authentication between two mobile stations or

a mobile station and a fixed Internet server Visit the Internet public resourc

• no authentica tion is needed

WIRELESS TRANSMISSION PRIVACY (3) Authentication and key negotiation proto

col between two mobile sta tions belonging

WIRELESS TRANSMISSION PRIVACY (4) Scheme variation in various authenticatio

n scenarios

SECURITY ANALYSIS (1) MS1 finds MS2’s home address and creates a nonce w

ith the corresponding hash value HA1 decrypts the message from MS1; HA1 realizes that

MS1 intends to authenticate with a third party CA decrypts the message from HA1 and verifies IDHA1 HA1 decrypts the message from CA, and gets the public

key and device ID of HA2. HA1 stores the pubHA2 and IDHA2 pair

HA2 will buffer the latter if the latter comes that must not be compromised

SECURITY ANALYSIS (2)

AUTHENTICATION AND KEY NEGOTIATION DEMONSTRATION demonstration uses RSA as the public key al

go rithm •DES as the symmetric algorithm •MD5 as one-way hash functions

If the slowest net work connection speed is 14.4 kb/s in the cellu lar network with overhead of the transmission considered •data transmission can be fin ished in less than 3 s

SUMMARY The proposed architecture offers a smooth tr

ansition of wireless LAN hot spots from non-roaming-supported to seamless-roam-ing-supported

A fast network switchover mechanism is available to improve the performance of stream ing applications

wireless transmis sion security is carefully considered

心得自從 2000年 3G行動網路開放以來，藉由市場發展與級數上的演進，逐漸發現到單一網路無法滿足行動上網的全方位需求，於是開行推行雙網的建佈，但由於 3G與無線網路基本運作方式的不同，加以行動上網對於無縫性通訊與安全性的要求，導致建構此一大型網路，面臨許多問題，從此 3篇 paper中，看到了這些問題的解決方案，相信對未來行動上網的建設有相當的助益。

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