ABOUT WIFI AND WIMAX

1. WiMAX Vs Wi-Fi

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WiMAX
 Worldwide Interoperability for Microwave Access
 Brand licensed by the WiMax Forum.
 “a standards-based technology enabling the delivery of
last mile wireless broadband access as an alternative to
cable and DSL”
 WiMAX was seen as more of a Metropolitan Area
Network (MAN) technology providing a much larger
coverage.
 Based on IEEE 802.16

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WiMAX
WiMAX, in fact, comes in two forms, a so called ‘fixed
WiMAX’ and a ‘mobile WiMAX’.
WiMAX in its fixed form is seen as a possible alternative
to expensive cable and fibre deployment.
It is faster to deploy and less expensive and it also offers
operators more flexibility in terms of deployment time
frame and possible installation areas.
3G or other cellular network operators could see this as a
potential substitute or as a complement to their cellular
product.

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WiMAX Architecture
MIB – Management Information Base

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Wi-Fi
 Stands for Wireless Fidelity.
 Brand licensed by the Wi-Fi Alliance.
 Wi-Fi is a local area network technology that was
originally thought to replace the thousands of miles of
LAN cables.
 Wireless Local Area Networks (WLAN)
 Based on IEEE 802.11

6. Wi-Fi
Wi-Fi has grown from being just a LAN cable
replacement technology to a public wireless access
technology.
Cheap and readily available equipment.
WiFi has been viewed as complementary to 3G and other
mobile standards as it has worked to enhance mobile
services offered by operators.
It’s coverage is not as great as that of 3G, but it gives a
much higher transmission rate than mobile technology.
Handoff between WiFi access points is still not possible
and, therefore, it is known more as a wireless access
technology than a mobile technology.
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7. New developments are taking place within the 802.11
standardization group
With the increasing popularity of VoIP, many see WiFi
as one of the possible means of using VoIP with some
form of mobility
802.11r for wireless VoIP and other real time
applications
802.11s for meshed WiFi networking
Making WiFi more mobile could make it more of a
substitute to mobile technologies
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Wi-Fi

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Wireless Systems

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802.11 Protocol Stack

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802.16 protocol stack

11. 802.11 802.16
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Scalability
Channel bandwidths can be chosen by
operator (e.g. for sectorization)
1.5 MHz to 20 MHz width channels. MAC
designed for scalability independent of
channel bandwidth
MAC designed to support thousands of
users.
Wide, fixed (20MHz) frequency
channels
MAC designed to support 10’s of
users

12. Bit Rate: Relative Performance
20 MHz 54 Mbps ~2.7 bps/Hz
802.16a ~5.0 bps/Hz
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63 Mbps*
10, 20 MHz;
1.75, 3.5, 7, 14 MHz;
3, 6 MHz
802.11a
Channel
Bandwidth
Maximum
bps/Hz
Maximum
Data Rate
* Assuming a 14 MHz channel
802.16a is designed for metropolitan performance

13. Coverage
802.11 802.16
 Optimized for outdoor NLOS
performance
 Standard supports mesh network
topology
 Standard supports advanced antenna
techniques
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 Optimized for indoor performance
 No mesh topology support within
ratified standards
802.16 is designed for market coverage

14. Range
802.11 802.16
 Optimized for up to 50 Km
 Designed to handle many users
spread out over kilometers
 Designed to tolerate greater
multi-path delay spread (signal
reflections) up to 10.0μ seconds
 PHY and MAC designed with multi-mile
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range in mind
 StandardMAC;Sectoring/MIMO/AMC
for Rate/Range dynamic tradeoff
 Optimized for ~100 meters
 No “near-far” compensation.
 Designed to handle indoor multi-path(
delay spread of 0.8μ
seconds).
 Optimization centers around
PHY and MAC layer for 100m
range.
 Range can be extended by
cranking up the power – but MAC
may be non-standard.
802.16 is designed for distance

15. 802.11 802.16a
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Quality of Service (QoS)
 Grant-request MAC
 Designed to support Voice and
Video from ground up
 Supports differentiated service
levels: e.g. T1 for business
customers; best effort for residential.
 TDD/FDD/HFDD – symmetric or
asymmetric
 Centrally-enforced QoS
 Contention-based MAC (CSMA/CA)
=> no guaranteed QoS
 Standard cannot currently
guarantee latency for Voice, Video
 Standard does not allow for
differentiated levels of service on a
per-user basis
 TDD only – asymmetric
 802.11e (proposed) QoS is
prioritization only
802.16a is designed for carrier class operation

16. Security
802.11 802.16a
Triple-DES (128-bit) and RSA
(1024-bit)
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Existing standard is WPA + WEP
802.11i in process of addressing
security
802.16a maintains fixed wireless security

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WiMAX vs Wi-Fi

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WiMAX vs Wi-Fi

19. Comparison of WiMAX, WiFi and 3G technology
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20. 802.11 and 802.16 both gain broader industry
acceptance through conformance and
interoperability by multiple vendors
802.16 complements 802.11 by creating a
complete MAN-LAN solution
802.11 is optimized for license-exempt LAN
operation
802.16 is optimized for license-exempt and
licensed MAN operation.
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802.11 vs 802.16: Summary

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Will WiMAX displace WiFi?
 WiMAX will not replace
WiFi completely, but work
TOGETHER
 Intel is currently integrating
WiMAX and WiFi into a
single Centrino chip.
 WiFi’s primary role will
always be autonomous
hotspot service
 areas (indoor and outdoor 0
ft. < cell radii <500 ft.).
 WiMax will ultimately
replace WiFi in large-scale
(greater than 1mi.Sq.)
commercial and public
roles.

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Wi-fi and WiMax Together