VoIP over WLAN
(Voice over IP over Wireless Local Area Network)
Diplomityöseminaari
1.6.2004
Heikki Hintikka at Song Networks Oy
Supervisor: Professor Heikki Hämmäinen
Instructor: Pauli Saari, Quality Management Director
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
24.7.2016
VoIP over WLAN
2
VoIP over WLAN – the concept
VoIP
WLAN
Free phone calls over the Internet
Wireless broadband up to 54 Mbps
No toll quality voice service like PSTN
Data rates depend on distance
Used in many enterprise environments
Standards evolving to meet user needs
QoS factors very important for voice quality
Still challenges to face
24.7.2016
VoIP over WLAN
3
Thesis ToC













1
1.1
1.2
1.3
1.4
1.5
1.6
2
3
4
5
6
7
24.7.2016
INTRODUCTION
Background to VoWLAN
Main issues in VoWLANs
Problem definition
Scope of study
Methodology
Structure of the study
WLAN
VoIP
Usability and Deployment
Testing of VoWLAN (SOHO environment)
Market and Business Analysis
Trends and Forecast
VoIP over WLAN
4
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
24.7.2016
VoIP over WLAN
5
IEEE 802.11 (WLAN) standards
802.11e
802.11b
802.11f
DSSS
11 Mbps
802.11i
2,4 GHz
802.11a
802.11g
24.7.2016
54 Mbps
5 GHz
OFDM
802.11h
VoIP over WLAN
6
WLAN’s four S’s – 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
24.7.2016
VoIP over WLAN
7
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.
24.7.2016
VoIP over WLAN
8
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
24.7.2016
VoIP over WLAN
9
Security
 Encryption mechanisms
 WEP – Wired Equivent Privacy, weak nowadays
 TKIP – Temporary Key Integrity Protocol, taken WEP’s 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
24.7.2016
VoIP over WLAN
10
Evolution of WLAN security
802.11i
WEP
WPA
RC-4
EAPs
MD5
RADIUS
802.1X
EAP-TTLS
EAP-SIM
WEP
TKIP
MIC
PEAP
EAP-TLS
EAPMD5
AES
EAP-?
LEAP
CCMP
24.7.2016
VoIP over WLAN
11
Devices and products
 End user devices: PDAs, laptops, smart phones etc.
 Network elements
 Usability important
 Features and characteristics:




24.7.2016
interoperability
seamless handover
roaming
hybrid solutions
VoIP over WLAN
12
Deployment environments – Hotspot example
HOTSPOT
Local services
802.1X / EAP
Internet
Router
Access
controller
PEAP / EAP /
RADIUS
WISP /
WISP
aggregator
Core network
packet data GW
CELLLAR OPERATOR
(GSM/CDMA)
Enterprise
RADIUS
interworking GW
24.7.2016
HLR / HSS /
RADIUS
GW
Fixed line
aggregator
AAA server
VoIP over WLAN
13
Provisioning model – one bill roaming
Roaming intermediary
Home entity
Hotspot operator
AAA server
AAA server
AAA server
direct AAA exchange
RADIUS
User data
Access
cotroller GW
Billing
Internet
End user
24.7.2016
Roaming user
VoIP over WLAN
14
Testing of VoIP over WLAN - SOHO

Prioritizing VoWLAN in SOHO environment
SIP-based
VoIP server
Internet
Test premises
edge router
WISP
operator
network
router / CPE
DSLAM
VPN server
24.7.2016
VoIP over WLAN
15
Results: QoS parameters
– delay and jitter
Downstream Jitter
Downstream Delay
0,040000
0,120000
0,020000
0,100000
Jitter (s)
Delay (s)
0,000000
-0,020000
-0,040000
0,080000
0,060000
0,040000
-0,060000
-0,080000
0,020000
-0,100000
0,000000
Time (s)
Time (s)
24.7.2016
VoIP over WLAN
16
VoIP prioritizing in hotspots
24.7.2016
VoIP over WLAN
17
Markets & forecast
 Markets are growing fast – price erosion
 Multiple manufacturers making devices
 inter-network capabilities (GSM/GPRS/CDMA)
 WISPs, network operators, alliances,
 roaming – coverage/clients
 Competitors?
 3G, UWB, Bluetooth, WiMAX
 Different stakeholders in business
24.7.2016
VoIP over WLAN
18
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
24.7.2016
VoIP over WLAN
19