The slide describes the WiMax technology.

1. World Interoperability for Microwave
Access
(IEEE 802.16)
WiMAX

2. Current Scenario
There are basically three different options to access Internet
today:
Broadband access – In home, either a DSL or cable modem. At the office.
WiFi access – In home, Wi-Fi router to surf the Web while lounging with
laptop. It can find Wi-Fi hot spots in restaurants, hotels, coffee shops and
libraries.
Dial-up access – By using dial-up, chances are that either broadband access is
not available, or broadband access is too expensive.

3. Current Scenario
 The main problems with broadband access are that it is pretty expensive and
it doesn't reach all areas.
The main problem with Wi-Fi access is that hot spots are very small, so
coverage is sparse.
 To solve all of these problems, a new technology would provide:
• The high speed of broadband service.
•Wireless rather than wired access, so it would be a lot less expensive than
cable or DSL (Digital Subscriber Line) and much easier to extend to suburban
and rural areas.
•Broad coverage like the cell phone network instead of small Wi-Fi hotspots.

4. Wireless Broadband
This system is called WiMAX (Worldwide Interoperability for
Microwave Access, IEEE 802.16).
 Also known as Wireless Metropolitan Area Network (Wireless MAN).
 High bandwidth wired access networks like fiber optic, cable modems and
DSL.
 Optimized for IP- based high speed wireless broadband to provide for a
better mobile wireless broadband internet service.
Large range & high transmission rate
 To provide network access to buildings through exterior antennas
communicating with radio base stations.
 Networks can be created in just weeks by deploying a small number of base
stations on buildings or poles to create high capacity wireless access systems.

5. WiMAX Vs. Wi-Fi
Wi-Fi:
• IEEE 802.11a – OFDM, Maximum rate = 54 Mbps
• IEEE 802.11b– DSSS, Maximum rate = 11 Mbps
• IEEE 802.11g – OFDM, Maximum rate = 54 Mbps
• Range < 100 meters
• Indoor Environment
• No admission control, no load balancing
• No QoS
WiMAX:
• IEEE 802.16 – OFDM, Maximum rate = 50 Mbps
• IEEE 802.16e – OFDM, Maximum rate = 30 Mbps
• Range = 4 – 6 miles
• Outdoor Environment
• Admission control and load balancing
• Five QoS classes enforced by base station

6. WiMAX is not Wi-Fi

7. Overview of IEEE 802.16

8. Sub-standards of IEEE 802.16
 IEEE 802.16.1 - Air interface for 10 to 66 GHz
 IEEE 802.16.2 - Coexistence of broadband wireless
access systems
 IEEE 802.16.3 - Air interface for licensed frequencies, 2
to 11 GHz

9. Basics of IEEE 802.16
IEEE 802.16 standards are concerned with the air interface
between a subscriber’s transceiver station and a base
transceiver station
 The Physical Layer
 MAC Layer
 Convergence Layer

10. IEEE 802.16 Protocol Architecture

11. Physical Layer
 Specifies the frequency band, the modulation scheme,
error-correction techniques, synchronization between
transmitter and receiver, data rate and the multiplexing
structure
 Both TDD and FDD alternatives support adaptive burst
profiles in which modulation and coding options may be
dynamically assigned on a burst-by-burst basis
 Three physical layer for services: Wireless MAN-SC
(Single Carrier Modulation,10-66 GHz), Wireless MAN-
OFDM (256 carrier modulation) and Wireless MAN-OFDMA
(2048 carrier modulation)

12. Medium Access Control Layer
 Designed for point-to-multipoint broadband wireless
access
 Addresses the need for very high bit rates, both uplink
(from mobile station to the base station) and downlink (from
the base station to mobile station)
 Services like multimedia and voice can run as 802.16
MAC is equipped to accommodate both continuous and
burst traffic
 ARQ Protocol
 To support different technologies i.e. IPV4, IPV6.
Ethernet and ATM

13. Convergence Layer
 To provide functions specific to the service
 Bearer services include digital audio/video multicast,
digital telephony, ATM, Internet access, wireless trunks in
telephone networks and frame relay

14. Advanced Features of WiMAX
 An important and very challenging function of the WiMAX system is
the support of various advanced antenna techniques, which are essential
to provide high spectral efficiency, capacity, system performance, and
reliability.
 Two Type of Services:
WiMAX can provide two forms of wireless service:
1) Non-line-of-sight: Wi-Fi sort of service. Here a small antenna on a
computer connects to the WiMAX tower. In this mode, WiMAX uses a
lower frequency range -- 2 GHz to 11 GHz (similar to Wi-Fi).
2) Line-of-sight: service, where a fixed dish antenna points straight at
the WiMAX tower from a rooftop or pole. The line-of-sight connection
is stronger and more stable, so it's able to send a lot of data with fewer
errors. Line-of-sight transmissions use higher frequencies, with ranges
reaching a possible 66 GHz.

15. Advanced Features of WiMAX
 Very high peak data rates:
WiMAX is capable of supporting very high peak data rates. In fact, the
peak PHY data rate can be as high as 74Mbps when operating using a
20MHz wide spectrum.
More typically, using a 10MHz spectrum operating using TDD scheme
with a 3:1 downlink-to-uplink ratio, the peak PHY data rate is about
25Mbps and 6.7Mbps for the downlink and the uplink, respectively.

16. Advanced Features of WiMAX
 Scalable bandwidth and data rate support:
WiMAX has a scalable physical-layer architecture that allows for the
data rate to scale easily with available channel bandwidth.
For example, a WiMAX system may use 128, 512, or 1,048-bit FFTs
(fast fourier transforms) based on whether the channel bandwidth is
1.25MHz, 5MHz, or 10MHz, respectively. This scaling may be done
dynamically to support user roaming across different networks that may
have different bandwidth allocations.

17. Advanced Features of WiMAX
 Quality-of-service support:
The WiMAX MAC layer has a connection-oriented architecture that is
designed to support a variety of applications, including voice and
multimedia services.
WiMAX system offers support for constant bit rate, variable bit rate,
real-time, and non-real-time traffic flows, in addition to best-effort data
traffic.
WiMAX MAC is designed to support a large number of users, with
multiple connections per terminal, each with its own QoS requirement.

18. Advanced Features of WiMAX
 Robust security:
WiMAX supports strong encryption, using Advanced Encryption
Standard (AES), and has a robust privacy and key-management
protocol.
The system also offers a very flexible authentication architecture based
on Extensible Authentication Protocol (EAP), which allows for a
variety of user credentials, including username/password, digital
certificates, and smart cards.
 Support for mobility:
The mobile WiMAX variant of the system has mechanisms to support
secure seamless handovers for delay-tolerant full-mobility applications,
such as VoIP.