Download Strategy for VOIP

IEEE NJ Coast Section
Seminar on Wireless LAN &
IP Telephony
Session W3
Toward 4G Networks
Ramachandran Ramjee, Ph.D.
[email protected]
http://www.bell-labs.com/~ramjee
Wide-Area Wireless Standards Evolution
1G
2G
“2.5G”
3G/ IMT-2000 Capable
Existing Spectrum
Analog
AMPS
IS-95-A/
cdmaOne
IS-95-B/
cdmaOne
New Spectrum
cdma2000 1X (1.25 MHz)
cdma2000 3X (5 MHz)
1XEV DO: HDR (1.25 MHz)
136 HS
EDGE
IS-136
TDMA
TACS
GSM GPRS
EDGE
GSM
WCDMA
HSCSD
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
2
Other wireless standards













802.11/802.11b - 2-11 Mbps - uses 2.4GHz spectrum
802.11a - 54 Mbps - Orthogonal Frequency Division Multiplexing
(OFDM)
HiperLan2 - 50Mbps - local-area networks - uses 5GHz spectrum
Bluetooth - 720 kbps - very limited range using 2.4GHz spectrum
ARDIS - 19.2 Kbps - IBM/Motorola - slotted CSMA
MOBITEX - 9.6 Kbps - RAM mobile-slotted CSMA
CDPD - 19.2 Kbps - DSMA/CD using AMPS
Metricom - Frequency Hopped SS - 28.8 Kbps, 128 kbps upgrade uses the ISM 900 Mhz band
iDEN - 20kbps - uses Mobile IP, supports WAP
DECT/CT2 - cordless, low-mobility - 32kbps - FDMA/TDMA
PHS - cordless system for microcell/indoor use, Japan - 128 Kbps TDMA
iMode - 9.6 Kbps - packet data service, currently uses PDC
WAP - Wireless Application Protocol - currently circuit-switched data
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
3
Observations




The ‘G’ in #G stands for Generation and typically refers to the
generation of wide-area wireless network’s air interface
While the 4G air interface has not been standardized yet, a
plethora of wireless standards are prevalent and will continue to
co-exist
Dominant among these are CDMA2000, WCDMA, and 802.11based systems
Today, each of these air interfaces has its own network
architecture standards though the network provides similar
functionality of mobility and location management
 A unified network architecture based on IP that provides a
common mobility and location management mechanism can
serve as the 4G network of the future while different air
interfaces simply plug into this network
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
4
Outline


Motivation
IP Mobility
– Macro-mobility: Mobile IP
– Micro-mobility: HAWAII

IP Paging
– HA/FA paging
– Domain paging

Interworking of Wireless LANs with 3G Networks
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
5
Motivation: Why IP?

Migration of wireless access networks to IP
allows
–
Support for anticipated growth of the wireless
Internet access
• merging of services for wireline and wireless networks
• merging of wireless voice and data networks
– Reduced product and operational costs of IP
infrastructure
• availability of “commodity” hardware, software, and services
• increased efficiency of packet-based networks for combining
voice and data
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
6
Industry Directions for Wireless Networking
1998
1994
1990

1992
3M Internet
Users
1995
2002
153M Internet
Users
Cellular Telecom Approach
–

1st UMTS
customers
GPRS/UMTS
standards begin
FPLMTS
standards begin
Efforts to define wireless data networking standard (General
Packet Radio Service/GPRS, UMTS) begin before full impact of
Internet explosion is felt
Internet-Based Approach
–
Use Internet standards for networking and mobility with
extensions to inter-operate and support cellular air interfaces
(e.g., GPRS, CDMA)
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
7
Clash of models

Telecom/cellular model
Approach: Extend current wireless circuit-based infrastructure to
support wireless internet data
– Flexibility at the cost of complexity and efficiency (e.g. X.25
support in GPRS, PPP support in CDMA)
+ Rich functionality through experience (e.g., paging, micromobility)

Internet model
Approach: Extend current internet data-based infrastructure to
support wireless internet data
+ Simplicity using IP (support other protocols, e.g. X.25, through
tunneling if necessary)
– Missing functionality (e.g., paging, micro-mobility)
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
8
Emerging Mobile Packet Networks:
GPRS and UMTS
Tunneled packets
using GTP
MD

Radio
Access
Networks
SGSN
GGSN
Intranet
Regular routing
Host
Internet
SGSN
Compatible with cellular telecom networks
+ may be deployed leveraging existing infrastructure
– requires separate advances from the Internet

Specialized nodes manage mobility and forward packets
+ requires no changes to fixed hosts or intermediate routers
– results in tunneling and triangular routing
– special failure recovery mechanisms needed

Inter-SGSN handoffs always managed by GGSN
– high update overhead
– slow handoffs
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
9
Emerging Mobile Packet Networks:
CDMA2000 and 802.11 (Mobile IPv4)
MD

Tunneled packets
using Mobile IP
Radio FA
Access
FA
Networks
HA
Regular routing
Internet
Host
Compatible with regular IP networks and hosts
+ most Internet advances apply

Specialized agents manage mobility and forward packets
+ requires no changes to fixed hosts or routers
– results in tunneling and triangular routing
– special failure recovery mechanisms needed

Handoffs always managed by Home Agent
– high update overhead
– slow handoffs
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
10
Trends

Local and Wide-area wireless data networks
–

IP functionality in access network elements
including base stations
–

high and low mobility users
homogeneous IP-based access network
Diverse applications
–
quality of service support necessary
 Mobility has to be processed locally
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
11
Micro-mobility: Design Goals

Scalability
–

Limit disruption
–

local restoration of reservations
Reliability
–

avoid tunneling where possible
Quality of Service (QoS) support
–

forward packets if necessary
Efficiency
–

process updates locally
leverage fault detection mechanisms in routing protocols
Transparency
–
minimal impact at the mobile host
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
12
Hierarchy and unique address

Hierarchy through domains
–
–

Mobile-IP for movement between domains
HAWAII Path Setup for movement within domain
Users retain their unique IP address while
moving within a domain
–
–
Home address could be dynamically assigned
Co-located care-of address used in foreign domain
 Unique
and unchanging address limits
updates to Home Agent and simplifies QoS
support in the network
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
13
HAWAII: Enhanced Mobile IP
Internet
Domain
Router
R
R
Domain
Router
R
R
R
R
R
R
R
R
R
R
MD
Local mobility

Mobile IP
Local mobility
Distributed control: Reliability and scalability
– host-based routing entries in routers on path to mobile

Localized mobility management: Fast handoffs
– updates only reach routers affected by movement

Minimized or Eliminated Tunneling: Efficient routing
– dynamic, public address assignment to mobile devices
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
14
Power-up
Domain
Root
Router 2
1
2 R3 4
Internet
1.1.1.100-> port
3,
239.0.0.1
Domain
Root
Router 1
1
2 R
3 4
3
4
1.1.1.100->port 4,
1
239.0.0.1 2 R 5
3 4
5
1 R 4
2 3
1
2 R 5
3 4
2
BS1
BS2
BS3
1
BS4
1.1.1.100->wireless,
5
239.0.0.1
MY IP: 1.1.1.100
BS IP:1.1.1.5
Mobile IP
HAWAII
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
15
Soft-State

Host-based routing entries maintained as
soft-state

Base-stations and mobile hosts periodically
refresh the soft-state

HAWAII leverages routing protocol failure
detection and recovery mechanisms to
recover from failures

Recovery from link/router failures
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
16
Failure Recovery
Domain
Root
Router 2
1
2 R3 4
Internet
Domain
Root
Router 1
1
1.1.1.100-> port
2 R
4,
3 4
239.0.0.1
3
5
1 R 4
2 3
2
1.1.1.100->port 3,
239.0.0.1
1
R 5
3 4
2
BS1
BS2
BS3
1
1
2 R 5
3 4
BS4
1.1.1.100->wireless,
239.0.0.1
MY IP: 1.1.1.100
BS IP:1.1.1.5
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mobile IP
HAWAII
Mar 27, 2002
17
Path Setup Schemes

Host-based routing within the domain

Path setup schemes selectively update local
routers as users move

Path setup schemes customized based on
user, application, or wireless network
characteristics

Micro-mobility handled locally with limited
disruption to user traffic
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
18
Micro-Mobility
Domain
Root
Router 2
1
2 R3 4
5
1 R 4
2 3
Domain
Root
Router 1
1
2 R
3 4
1.1.1.100-> port 3,
239.0.0.1
Internet
1.1.1.100->port 3 (4),
1
239.0.0.1
2 R 5
3 4
4
2
3
BS1
BS2
1.1.1.100->wireless,
1 5
239.0.0.1
MY IP: 1.1.1.100
BS IP:1.1.1.2
1
2 R 5
3 4
BS3
BS4
1.1.1.100->port 1(wireless),
239.0.0.1
Mobile IP
HAWAII
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
19
Macro-Mobility
Domain
Root
Router 2
1
2 R3 4
Domain
Root
Router 1
Mobile IP Home Agent:
1
1.1.1.100->
2 R
4
3
1.1.2.200
Internet
1.1.2.200-> port 3,
239.0.0.1
3
5
4
5
1 R 4
2 3
1.1.2.200->port 2, 6
239.0.0.1
1
2 R 5
3 4
1
2 R 5
3 4
2
BS1
1
BS2
BS3
7 1.1.2.200->wireless,
239.0.0.2
MY IP: 1.1.1.100
BS IP:1.1.2.1
COA IP:1.1.2.200
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
BS4
Mobile IP
HAWAII
Mar 27, 2002
20
Simulation Topology
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
21
Performance: Audio and Video
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
22
Performance: TCP


TCP - Web transfers in
Mobile IP: Interaction
between Tunneling and
TCP Path MTU
discovery results in 1
round trip wasted for
each object.
TCP - File transfers: 515% improvement over
Mobile IP
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
23
Update Rates
BD
RD
r
v
LB
TR
Y
TM
g
Network Model
Domain
Router
• 39 users/sq. miles
• users moves at 112 Km/hr.
Router 1
Router 7 • base stations cover 7 Km2
...
BS1
... BS-20
BS1
BS20
rn
Mobile IP Updates at
MIP =
Home Agent:
– Varies linearly with # of base stations
L B
B
+
D
p
Base stations/domain router
2nd level routers/DR
User density
User velocity
Base station perimter
HAWAII refresh timer
# of updates/message
Mobile IP lifetime
% users outside home domain
r
2
L B
16 T
B
D
M
<<1, local mobility
Hawaii Updates at Domain
Router:
– Varies O(BD1/2)
H
+
=
rn
rn
L B
B
+
D
p
L B R
B
p
D
D
gr L2B
B
D
16 TM
r L2B B
D
+
16YTR
M-IP
Hawaii
aggregation
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
24
Performance: Update Rates

Scalability at the Domain Root Router
–
–

Number of entries: entries are from a given domain’s IP
subnet -> perfect hashing for route lookup.
Number of updates: updates for Mobile IP varies linearly with
the number of base stations in domain whereas in HAWAII,
updates vary with the square root of number of base stations
in domain.
Based on FreeBSD implementation, for a
typical network configuration, update ratio of
Mobile IP to HAWAII is 3:1 and CPU utilization
ratio is 9:1.
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
25
Standardization: IETF SeaMoby Working Group

Draft-seamoby-ietf-mm-problem-01.txt identifies the
goals for a new IETF micro-mobility protocol:
 Mobility without changing routable IP address
 Use Mobile IP for inter-domain mobility
 Use Mobile IP for signaling from the mobile host
 IP version neutral
 Optimized routing
 Plug & Play
 Inter-technology/heterogeneous mobility support
 Inter-operate with existing QoS protocols
HAWAII appears an excellent fit!
Work is in IRTF now.

IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
26
Changes from Mobile IP (rfc2002)






Previous Foreign Agent Notification Extension (Route
Optimization draft)
NAI extension (NAI draft)
Mobile challenge-response extension (Challenge
Response draft)
NAI in foreign agent advertisements to detect domain
changes (Private addresses draft)
Register with foreign agent while using co-located
addresses
Allow split Mobile-IP registrations at the foreign agent
(regionalized tunnel draft)
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
27
HAWAII: Benefits Summary
Scalability through reduced updates as micro-mobility
transparent to home agents
 Limited disruption of traffic as Path Setup Schemes are
optimized for the environment
 Efficiency through reduced data packet header
overhead as no tunneling in a (large) home/power-up
domain
 Ease of QoS support: unique address
 Reliability through soft-state
 Transparency to hosts that use Mobile IP
 Integration with existing wireless infrastructure

IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
28
Outline


Motivation
IP Mobility
– Macro-mobility: Mobile IP
– Micro-mobility: HAWAII

IP Paging
– HA/FA paging
– Domain paging

Interworking of Wireless LANs with 3G Networks
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
29
What is Paging?
Mobile Host State Diagram
“Idle” mobile hosts update network less frequently
than “active” mobile hosts

Network has only approximate location information
for idle mobile hosts
 Network determines the exact location by
paging to deliver packets

IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
30
IP Paging Outline





Motivation
IP Paging Architectures
Performance
IETF Standardization (SeaMoby Working
Group)
Summary
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
31
Paging in wireless networks (1): GPRS, UMTS
Tunneled packets
using GTP
MD

Radio
Access
Networks
SGSN
GGSN
Intranet
Regular routing
Host
Internet
SGSN
Paging for voice initiated differently (MSC) from data (SGSN)
+ may be deployed leveraging existing infrastructure
– requires separate mechanisms

Specialized nodes, protocols (BSSGP) manage paging
+ requires no changes to intermediate routers
– separate advances from other paging protocols
– special failure recovery mechanisms needed
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
32
Paging in wireless networks (2):
CDMA2000, Mobile IP
MD
Tunneled packets
using Mobile IP
Radio
FA
Access
Networks FA
HA
Regular routing
Internet
Host
Paging for voice initiated differently (MSC) from data
(RAN/MSC)

+ may be deployed leveraging existing infrastructure
– requires separate mechanisms
– No paging in Mobile IP

Specialized nodes, protocols (IS2001) manage paging
+ requires no changes to fixed hosts or routers
– separate advances from other paging protocols
– special failure recovery mechanisms needed
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
33
Why IP paging?
As wireless access networks migrate to IP, IP
paging allows
 common infrastructure to support different
wireless technologies
– seamless merging of LAN/WAN
– avoids duplication of paging protocols, resulting in cost
savings

deployment of sophisticated paging
algorithms
– leverages the support of multicast, if available
– user-customized paging areas
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
34
IP Paging Goals

Efficiency
limit updates from mobile host when idle to conserve battery
power

Scalability
push paging initiation closer to base station

Reliability
allow paging initiation to occur at any router/base station
(no single point of failure)

Flexibility
allow for fixed, hierarchical, or user-defined paging areas
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
35
IP Paging Architectures
HA initiates page
Uniform mobility management
– wireless LANs, outdoor
Home
Agent
Internet
R
R
Old FA initiates page
Foreign
Agent
Mobile IP Foreign
Paging Area Agent
R
Domain
Paging
Area
Foreign
Agent
Any router initiates page
3 Options:
• Home Agent Paging
– Home agent buffers packets and initiates page to all Foreign Agents
– Can be controlled by corporate network
– Does not scale
• Foreign Agent Paging
– Last active Foreign agent buffers packets and initiate paging
– Distributes load
• Domain Paging
– Fully distributed, very scaleable and reliable
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
36
Home Agent (HA) Paging



Centralized at HA
Simple implementation
Issues/concerns
– Inefficient signaling: long
delays if HA far from mobile
host
– Scalability at HA
– Multicast-based addressing
of paging area needs global
visibility, scalability of
paging areas
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
37
Foreign Agent (FA) Paging

Initiated at previously
attached FA

Distributed among different
foreign agents in paging area

Simple implementation

Efficient: paging restricted to
local domain

Issues/concerns
– Reliability when previous FA
crashes
– Requires FA deployment
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
38
Domain Paging

Initiated at any node (router/base
station) in path from mobile to
root router

Completely distributed among
different nodes in domain

Highly scalable, reliable to node
failures

Efficient: paging restricted to local
domain

Issues/concerns
– implementation complexity
– router support
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
39
Router operation
Routing Paging
entry
entry
State
YES
YES
NO
YES
NO
NO
Active
Active
Null
NO
YES
Operation
Regular Forwarding
No paging support
Forward if default route exists,
else discard
Standby Paging:
If (packet arrives from DRR or I am DRR)
If (node is base station or no refresh from
downlink port or queuesize < threshold)
Initiate paging
else
Forward to port in paging entry
Endif
else
Forward along default route
Endif
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
40
Implementation

All three paging protocols
implemented in FreeBSD

Paging protocol processing in
user space, data forwarding in
kernel space

Paging implementation does
not affect fast path
performance - use of virtual
interfaces

Implementation used to
measure processing load of
different paging tasks - results
to drive large scale simulation
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
41
Paging
Domain
Root
Router 2
1
2 R3 4
Domain
Internet
Root
Router 1
1
2 R
4
1.1.1.100-> port 3, 3
239.0.0.1
5
1 R 4
2 3
Buffer
1.1.1.100->port 3,
1
1
239.0.0.1
2 R 5
2 R 5
3 4
3 4
1
1
4
BS1
BS2
1.1.1.100->wireless,
2 3
239.0.0.1
BS3
BS4
2
MY IP: 1.1.1.100
BS IP:1.1.1.2
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Paging
Data
HAWAII
Mar 27, 2002
42
Scalability (latency)

Simulation parameters
–
–
–
–
36-90 zones per domain
paging area size = 6
real, synthetic traces
processing times from
implementation

HA paging needs 5
processors for
comparable performance

FA paging scalable

Domain paging supports
highest paging load
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
43
Scalability (updates)



Large Paging Area size
results in fewer updates but
increases latency due to
higher paging processing
load
In FA/HA paging, updates
can occur due to movement
or when user is paged and
found at new location
In Domain paging, updates
are only due to movement results in least number of
updates
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
44
IP Paging – Reliability Results
Home
Agent
Domain Model
Mobile IP Model
Internet
R
IP
Paging Area R
FA
U
tHA
tFA
tR
N
tM


FA
Definition
Unavailability
HA recovery time
FA recovery time
Router recovery time
Number of intermediate routers
Mean time between failure
P(user moved from FA)
P(user changed domains)
DR/HA
R
FA
R
R
FA
Value
120 s
120 s
30 s
2
1 month
0.1
0.5
R
R
R
R
MRT (i )
U = icomponent
MTTF (i)
UHA = (tHA + tFA + NtR) tM
UFA = (tHA + tFA + tFA + NtR) tM
UDomain = (tHA + tFA + NtR) tM
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
45
IP Paging – Reliability Results
HA
FA
FA
HA
Domain
Domain
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
46
Standardization: IETF SeaMoby Working Group
Draft-ietf-seamoby-paging-problem-statement-02.txt identifies
need for IP paging (now RFC 3132)
 Draft-ietf-seamoby-paging-requirements-02.txt identifies
following requirements (now RFC 3154):

–
–
–
–
–
–
–
minimize impact on host’s power consumption
on receiving page, host must re-establish layer three link
efficient utilization of layer two, if available
support existing mobility protocols
flexible support for different paging areas
allow arbitrary mapping between paging areas, subnets
robust against failures, packet losses
FA, Domain paging suitable candidates!

IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
47
Summary
 IP-based
wireless access networks - efficient, cost-effective
 IP paging allows common infrastructure to support different
wireless interfaces including CDMA, GPRS, wireless LAN etc.
 Proposed three paging architectures: each has its applicability
–
–
–
HA paging useful in small networks with complete administrative control
FA paging simple, scalable, easily deployable
Domain paging scalable, flexible, reliable, most efficient
 Future
–
–
work
Standardization
Flexible and user-specific paging mechanisms
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
48
Outline


Motivation
IP Mobility
– Macro-mobility: Mobile IP
– Micro-mobility: HAWAII

IP Paging
– HA/FA paging
– Domain paging

Interworking of Wireless LANs with 3G Networks
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
49
Integrated Wireless Access Networks
The next wave of Internet access will be through high-speed wireless packet access



Ubiquitous access to Internet and applications
Always-on high speed packet data access
Islands of multi-technology RF access networks connected to core IP
network
Service Provider
“Home” Network
Billing
Service Provider
“Home” Network
Roaming
Mobility
Authentication
Agreements
Billing
Mobility
Authentication
Core IP
Network
Radio
Access
Network
Radio
Access
Network
Wide Area Wireless
Radio
Access
Network
Local Area Wireless
Hotspot/Enterprise
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
4G Wireless?
Mar 27, 2002
50
Overview

Goal
– Integrate 802.11 and wide-area wireless networks

Motivation
– Ability to choose 802.11 where available (substantial cost-bandwidth
advantage)
– 3G/802.11 integration can enhance existing wireless services and
offer new services.

Approach
– Integrate 802.11 with CDMA2000 &/or UMTS access networks for
data service

Benefits
• seamless mobility
• wider application spectrum
• lower access/transport cost for high bandwidth services
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
51
Background
Infrastructure
• 802.11 Network
– low cost, high-data rate (11Mbps  54Mbps)
– unlicensed spectrum  potential interference
– short range
– ORiNOCO, Apple, Cisco, etc.
• 2G/2.5G/3G Network
– high cost, low data rate (153kbps  2Mbps)
– licensed spectrum  less interference
– long range
– Lucent, Nortel, Nokia, Ericsson, etc.
End device
• Various new devices being announced
E.g. VisorPhone (Handspring) includes
PDA with 2G+ capability:
mobile phone ,
messaging,
internet access, ...
• Palm and Motorola
announced PDA with
GPRS (2.5G) capability
• NeoPoint, Sony, etc. claim
802.11/CDMA or 802.11/GSM prototypes
Observations
• Dissimilar networks and infrastructure
• Need for current end devices and applications to adapt between one network
type and another
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
52
Public Wireless Access Networks:
Why are they different?

Security is a major concern where a wireless shared medium is used in a public
environment
– More susceptible to eavesdropping and man-in-the-middle attacks
– Not behind firewall of friendly colleagues
– Secure access into the enterprise

Accessing service on other provider’s networks
– Roaming agreements, global roaming, shared revenue agreements
– Perform authentication and accounting for roaming subscribers

Mobility
– Efficient, seamless handoff of data sessions while moving across networks

Authentication
– User authenticates to the network
– Authentication at different layers: L2, L3, VPN, HTTPS


Integrated service across different air-interface technologies
Management and Home policy
– Distribute per user home policy and QoS levels of service to roamed networks
– Minimize exchanges with home network through efficient protocols and optimizations

QoS/ Levels of Service
– Air interface contention, fair network usage, and alleviating congestion in hot spot areas
– Cannot statically configure based on IP addresses

Mobile Client Software
– Mask complexities from the user: configuration, reauthentication, network selection
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
53
Challenges for Public Wireless Data Access


Security is a major concern where a wireless shared medium is
used in a public environment
Enabling roaming across networks
– enable integrated service across different air-interface technologies (e.g. 802.11 and
3G networks)
– Perform authentication and accounting for roaming subscribers
– Shared revenue arrangements to allow other service provider’s subscribers on
network

Improving the subscriber’s experience
– Minimizing subscriber interaction when roaming across networks and networks
using different air interface technologies
– One-time user authentication
– Automatic client terminal configuration for network

Being able to offer levels of service, fair network usage, and
alleviating network congestion in hot spot areas
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
54
Infrastructure Challenges

Authentication, Authorization, and Accounting (AAA)
– 3G networks use Home Location Register (HLR) and AAA servers to
perform authentication of link-layer and network-layer sessions
– 802.11 networks have their own link-layer authentication mechanisms
Perform separate administration or Merge user authentication profiles

Mobility
– 3G networks allow for hierarchical mobility management with link-layer
handoff, micro-mobility and macro-mobility support
– 802.11 networks support link-layer mobility and IP mobility mechanisms
 Perform IP mobility or use 3G mobility mechanisms in 802.11

Quality of Service (QoS) support
– Large disparity in bandwidth availability between 3G and 802.11
– 3G networks, unlike 802.11, are designed and engineered for QoS
 End device adaptation and QoS support in 802.11
Two approaches to address these challenges:
. Interconnect 3G networks with 802.11 using IP: peer-to-peer integration
. Integrate 802.11 into 3G networks: access network integration
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
55
Approach 1:Peer-to-Peer Integration
3G Network
3G Air
Interface
BS BS BS

3G Air
Interface
BS BS BS
HLR
Access
Network
3G Core
Network
AAA

M-IP
Agent
Intranet/Internet

Public/Enterprise
Data Network
M-IP
Agent
802.11 Air Interface
802.11
AP
802.11
AP
AAA
Overview
– Different administrative
domains connected through
IP
– Cross domain roaming is
supported by using standard
IP mobility, AAA
Advantages
– Easy to build (works today!)
– Fits All-IP philosophy
Disadvantages
– Requires Mobile IP in end
device for seamless roaming
– Potentially slower handoff and
inefficient data path
802.11 Air Interface
802.11
AP
802.11
AP
802.11 Wireless
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
56
Approach 2: Access Network Integration

3G Air
Interface
BS BS BS
3G Air
Interface
BS BS BS
Access
Network
HLR
3G Core
Network
AAA
M-IP
Agent
Internet
3G Gateway
802.11 Air Interface
802.11
BS
802.11
BS


Overview
– Operate 802.11 clusters under
the same 3G access network
– Mobility, AAA supported by
same mechanisms in 3G
network
Advantages
– Faster handoffs and more
efficient transport
– Integrated HLR/AAA
Disadvantages
– Customized 3G Gateway
necessary for each network
(CDMA, UMTS) results in
high cost
802.11 Air Interface
802.11
BS
802.11
BS
Integrated 3G/802.11 Network
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
57
Complete Service Picture
Accounting/
Applications/
Billing
Wireless Carrier Content
Network
Authentication
Network
Support
Roaming
Broker
Applications/
Content
Authentication
VPN
Mobility/
Roaming
Agreements
Wayport
Airport/
Enterprise
Handoff
Possibilities Intratech
Intranetwk
Handoff
Terminal
Possibilities
Corporate
Network
Internet
Wireless
Access
Subscriber
Service
Accounting
Wayport
Airport/
Enterprise
3G
Access
MobileStar
Starbucks
“Store-front”
3G
Access
802.11
802.11
Intratech
Internetwk
Handoff
Intratech
Internetwk
Handoff
Uninterrupted Applications:
Streaming, Email, Corporate VPN, Web
Intertech
Internetwk
Handoff
One Bill from
Wireless Carrier/
Bundled Data Package
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Built-in 802.11
Dual Interface
Built-in 802.11
3G data card
Intratech
Intranetwk
Handoff
Intratech
Internetwk
Handoff
Seamless Mobility/Roaming
for Subscriber/
Negotiated Rates with Partners
Mar 27, 2002
58
Combined Air Card
802.11/3G Integration Architecture using Peer-toPeer Approach and IP mobility
“Home” network
(3G carrier)
Billing
Servers
Home
AAA
Home
Agent
Internet
PDSN or
GGSN
PCF or
SGSN
3G Wireless
Access
Local AAA
Access Router
802.11 Gateway
BSC
Hot-spot 802.11
BS
BS
802.11
Access Points
Dual-mode terminal w/
MobileIP client
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
59
Industry 802.11 Security Status

Problems with existing products
–
–
–
–

Same shared static key used for encryption
Weak encryption through RC4 and short keys
User access is not authenticated to network servers
Proprietary solutions do not interoperate
802.11i Working Group Solutions
–
–
–
–
Per packet authentication
Temporary encryption keys and frequent rekeying
Stronger AES encryption and longer keys
Adoption of 802.1X standard
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
60
What is 802.1X?
“Home” Network
802.11 Network
Local AAA
802.11
Access Point
802.1X
EAPOL


Radius w/
EAP-Message
Home
AAA
Internet
EAP support
Radius Direct to HAAA or through Broker AAA
Framework for port-based network access control
Allows authentication & key derivation through EAP schemes
– Extensible Authentication Protocol (RFC 2284)
– Reuse RADIUS infrastructure to carry EAP frames
– Avoids preconfiguration of encryption keys at user terminals


Standard is not specific to wireless or 802.11
Allows 802.11 Access Points to support many different EAP
schemes
– 802.11 working group did not mandate particular EAP scheme
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
61
EAP-SKE scheme for 802.11 Security
Goal: dynamically establish security relationship between user
and public 802.11 access points with no prior configuration and
no subscription with owner of 802.11 network

•
•

Performs
Authentication,
Generates
Encryption key
and
key material
EAP-SKE IETF draft
Internet
802.11 Gateway
Use same authentication credentials
Use same keyed hash function (HMAC-MD5)
– Works with 802.1X, the accepted standard for initiating
authentication with 802.11 access points
Home
Agent
Home
AAA
EAP-SKE (Shared Key Exchange)
solution
– Authenticate user to Home AAA with minimal protocol
exchange
– Provide mutual authentication
– Home-AAA dynamically generates and distributes peruser per-session keys
– Use separate keys for authentication and encryption;
keys are never passed over the air
– Commonality with MobileIP and 3GPP2 standards
“Home” Network
Radius
exchange
802.1X/EAPOL
exchange
over air
– http://search.ietf.org/internet-drafts/draft-salgarelli-pppexteap-ske-00.txt
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Algorithm to construct
encryption key from passed
key material
Mar 27, 2002
62
Roaming Agreements Among 802.11 Service
Providers
Billing
Servers
“Home” network
(3G carrier)
Home
AAA
802.11WISP
Service Aggregator
Shared Revenue
Settlement DB
Roaming
Agreement
Roaming
Agreement
Shared Revenue
Settlement DB
802.11 Gateway
802.11 Gateway
802.11 Gateway
Large 802.11WISP
Service Provider
(e.g. Wayport)
Broker
AAA
Internet
Broker
AAA
Large 802.11
WISP
(Wayport)
Small 802.11
WISP
(Company Y)
Small 802.11
WISP
(Company X)
802.11
Access Points
Home
Agent
Same backend infrastructure
Supports 3G and 802.11
802.11
Access Points
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
802.11
Access Points
Mar 27, 2002
63
QoS Features for 802.11
Goal: Offering per user levels of service and
fairness to subscribers in 802.11 networks

Need QoS functionality in two spots of
possible congestion
– IP QoS on oversubscribed access link
– QoS for 802.11 air interface

Per user Level of Service policy
obtained from Home AAA database in
AAA protocol exchange
– dynamic rate limiting


Home
AAA
Gateway maps user population in
802.11 cells for achieving fairness and
preserving service level guarantees
DiffServ packet marking and traffic
policing
– Gateway can mark packets even with Mobile IP
tunnels
– Home agent marks packets for 802.11 destined traffic
Home
Agent
Internet
Edge Router
IP QoS on
access bottleneck
Access Router
802.11 Gateway
10 Mbps
10 Mbps
10 Mbps
802.11 QoS
over air
Gold Service User
Silver Service User
Bronze Service User
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
64
Integration Summary

802.11/3G integration provides choice of wireless internet access
while allowing seamless mobility

IP-based peer-to-peer interworking Solution easily extends to other
types of wireless access
– HDR, 802.11a, OFDM, Hiperlan2

Adapting CDMA2000 standards (security, accounting, mobility) for
the 802.11 environment allows client software and backend servers
can support both networks

Commonality across CDMA2000 and UMTS for integration with
802.11
– UMTS needs to have support for IETF protocols
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
65
Conclusion
 IP-based
wireless access networks are efficient and cost-
effective
 Combination
of HAWAII for micro-mobility and Mobile IP for
macro-mobility supports seamless and scalable handoffs
 IP paging
allows common infrastructure to support different
wireless interfaces including CDMA, GPRS, Wireless LAN etc.
 802.11/3G
integration provides choice of wireless internet
access while allowing seamless mobility
IEEE NJ Coast Section seminar on Wireless LAN & IP Telephony
Mar 27, 2002
66