3. Why we need broadband wireless
access?
• Fill the gap and high data rate wireless LAN
and mobile cellular networks.
• Provide high-speed mobile data and
telecommunications services
4. Wireless networks
•
Wireless PANs (Bluetooth – IEEE
802.15)
– very low range
– wireless connection to printers etc
•
Wireless LANs (WiFi – IEEE 802.11)
– infrastructure range
– home/office networking
•
Wireless MANs (WiMAX-802.16)
– Similar to cellular networks
– traditional base station
infrastructure systems
5. Standards
•
IEEE 802.16 (2001)
– Air Interface for Fixed Broadband Wireless Access System MAC and PHY
Specifications for 10 – 66 GHZ (LoS)
– One PHY: Single Carrier
– Connection-oriented, QoS, Privacy
•
IEEE 802.16a (January 2003)
– Amendment to 802.16, MAC Modifications and Additional PHY Specifications for 2 –
11 GHz (NLoS)
– Three PHYs: OFDM, OFDMA, Single Carrier
– Additional MAC functions: OFDM and OFDMA PHY support, Mesh topology support,
ARQ
•
IEEE 802.16d (July 2004)
– Combines both IEEE 802.16 and 802.16a
– Some modifications to the MAC and PHY
•
IEEE 802.16e (2005)
– Amendment to 802.16-2004
– MAC Modifications for limited mobility
10. Orthogonal Frequency Division
Multiplexing (OFDM)
• Multiplexing technique that divides the channel into
multiple orthogonal sub channels
• Input data stream is divided into several sub streams
of a lower data rate and each sub stream is modulated
and simultaneously transmitted on a separate sub
channel
• High spectral efficiency, resilient to interference, and
low multi-path distortion
12. Orthogonal Frequency Division
Multiple Access (OFDMA)
• Multiple-access/multiplexing scheme
– multiplexing operation of data streams from multiple users
– Dynamically assign a subset of sub channels to individual
users
• Wireless MAN-OFDMA based on scalable OFDMA
(SOFDMA)
– Support scalable channel bandwidths from 1.25 to 20 MHz
13. MAC Layer
Service Specific Convergence
Sublayer
MAC Common Part Sublayer
Interface to higher layer
protocols, classifies incoming
data, etc.
Core MAC functions (i.e.,
scheduling, connection
maintenance, fragmentation),
QoS control
Privacy Sublayer
Encryption, authentication,
secure key exchange
15. Applications
•
1.
2.
3.
4.
According to WiMax Forum it supports 4
classes of applications:
Multi-player Interactive Gaming.
Video Conference.
Web Browsing and Instant Messaging.
Media Content Downloads.
16. Advantage
• Low cast.
• It can support:
NLOS(non line of set)&LOS.
Mesh Network.
Point to Multipoint.
Handoff Technique.
• Coverage:50Km.
• Max Data Rate:70Mpbs.
18. Features
• Use wireless link with microwave or millimeter wave
radios.
• Use licensed spectrum
• Use point-to-multipoint architecture, tower-mounted
antennas
• Provide broadband and QoS, data transmissions.
19. Conclusions
• WiMax becomes the dominant Wireless MAN in
the world market.
• The end-users will have to be extremely easy to
install.
• Focus is too often on technologies
– Subscribers pay for services, not
technologies
– Broadband capabilities are important, but
bandwidth is not the only meter to assess service
22. References
• IEEE802.16
• Alcatel White Paper: WiMAX, making
ubiquitous high-speed data services a reality
• Intel White Paper: Understanding WiMAX
and 3G for Portable/Mobile Broadband
Wireless
• WiMAX Forum: www.wimaxforum.com
• http://en.wikipedia.org/wiki/WiMax