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VoIP over WLAN
(Voice over IP over Wireless Local Area Network)
Diplomityseminaari 1.6.2004
Heikki Hintikka at Song Networks Oy
Supervisor: Professor Heikki Hmminen
Instructor: Pauli Saari, Quality Management Director
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Contents
The concept of VoIP over WLAN Aims of research, main objectives
WLAN
Basics, factors of success, standards and future
VoIP
VoIP and speech, protocols, QoS
Security
standards & methods, currently (encryption, authentication), future
Devices and products
Deployment environments
example of hotspot, SOHO environment
provisioning model
TESTING (Access Link & SOHO environment)
Markets and forecast
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VoIP over WLANthe concept
VoIP WLAN
Free phone calls over the Internet
No toll quality voice service like PSTN
Used in many enterprise environments
QoS factors very important for voice quality
Wireless broadband up to 54 Mbps
Data rates depend on distance
Standards evolving to meet user needs
Still challenges to face
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Thesis ToC
1 INTRODUCTION 1.1 Background to VoWLAN
1.2 Main issues in VoWLANs
1.3 Problem definition
1.4 Scope of study
1.5 Methodology
1.6 Structure of the study
2 WLAN
3 VoIP
4 Usability and Deployment
5 Testing of VoWLAN (SOHO environment)
6 Market and Business Analysis 7 Trends and Forecast
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WLAN (Wireless Local Area Network)
Benefits: wireless broadband, low cost equipment, easy-to-use
Drawbacks: Issues with security, QoS, usability (roaming)
3 types of architecture: Infrastructure
Ad-hoc
Mesh networking
Radio interface: frequency bands, channels
Standard family (IEEE 802.11) evolving
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IEEE 802.11 (WLAN) standards
802.11bDSSS
11 Mbps
2,4 GHz802.11a
54 Mbps 5 GHz
OFDM 802.11h
802.11f
802.11e
802.11i
802.11g
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WLANs four Ss main criterias
Security
user data integrity, secure authentication, encryption
Service quality real-time applications (voice/video), QoS
Support
operational, functionality, interoperability, performance
Scalability flexible, easy-to-use services, develop higher quality
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VoIP
Voice over IP networks (RTP/UDP), Internet best-effort SIP (IETF) and H.323 (ITU-T), multimedia support
Gaining market space in enterprises
--> support for only one network
An important component in video calls
Many challenges when transmission media is wireless QoS parameters (delay, jitter, packet loss)
Security features increase delay etc.
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QoS (Quality of Service)
These QoS components ensure the performance
of voice calls across a data network:
Delay (ms)
Jitter (ms)
Packet Loss (%)
Congestion in access points
WLANs get disturbance of external factors
Bluetooth, microwave oven, trees, obstacles
Channel overlapping
Handover improvement
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Security
Encryption mechanisms
WEPWired Equivent Privacy, weak nowadays
TKIPTemporary Key Integrity Protocol, taken WEPs place
CCMP / AES (in 802.11i)
Authentication
WPA (Wi-Fi Protected Access): port-based 802.1X + EAPs/TKIP
802.11i: WPA extension plus other features CCMP/AES
pre-authentication
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Evolution of WLAN security
802.11i
RC-4
WEP
MD5
802.1X
WPA
RADIUS
EAPs
PEAP
EAP-?
EAP-SIM
EAP-
MD5
LEAP
EAP-TLS
EAP-TTLSTKIP
CCMP
MIC
AES
WEP
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Devices and products
End user devices: PDAs, laptops, smart phones etc.
Network elements
Usability important
Features and characteristics:
interoperability
seamless handover
roaming
hybrid solutions
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Deployment environmentsHotspot example
Internet
HOTSPOT
Enterprise
WISP /
WISPaggregator
Local services
Fixed line
aggregatorAAA server
CELLLAR OPERATOR
(GSM/CDMA)
RADIUS
interworking GW
HLR / HSS /
RADIUS
GW
Access
controller
Router
Core network
packet data GW
PEAP / EAP /
RADIUS
802.1X / EAP
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Provisioning modelone bill roaming
Hotspot operatorHome entityRoaming intermediary
AAA server
AAA serverAAA server
direct AAA exchange
Internet
Access
cotroller GW
RADIUS
User data
Billing
End user Roaming user
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Testing of VoIP over WLAN - SOHO
Prioritizing VoWLAN in SOHO environment
Internet
router / CPE
edge router
WISP
operator
network
Test premises
DSLAM
SIP-based
VoIP server
VPN server
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Results: QoS parameters
delay and jitter
Downstream Delay
-0,100000
-0,080000
-0,060000
-0,040000
-0,020000
0,000000
0,020000
0,040000
Time (s)
Delay(s)
Downstream Jitter
0,000000
0,020000
0,040000
0,060000
0,080000
0,100000
0,120000
Time (s)
Jitter(s)
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VoIP prioritizing in hotspots
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Markets & forecast
Markets are growing fastprice erosion
Multiple manufacturers making devices
inter-network capabilities (GSM/GPRS/CDMA) WISPs, network operators, alliances,
roamingcoverage/clients
Competitors? 3G, UWB, Bluetooth, WiMAX
Different stakeholders in business
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Conclusions and future work
Conclusions Overcoming QoS and security issues in VoWLAN designs and
implementations
Overcoming security flaws will be addressed by upcoming IEEE
802.11i standard
technical and economic business issues dealt with
Essential for providing QoS is to priritize VoIP streaming
Future work
traffic congestion in QoS guaranteed networks, where 802.11e has
been implemented Roaming, handover time reducement, standard affects in general
Support and interoperability