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WiMAX
Topics

WiMAX Protocol
 About
WiMAX
 Physical layer
 MAC layer
Fixed / Mobile WiMAX
 WiMAX vs Wi-Fi
 WiMAX applications
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What is WiMAX

Worldwide Interoperability for Microwave
Access
a
"last mile" broadband wireless access
(BWA) alternative to cable modem,
Digital Subscriber Line (DSL) or T1/E1
service.
Wireless Metropolitan Area Network (WMAN)
 Based on IEEE 802.16

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IEEE 802.16 Standards

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802.16.1-2001 (10-63 GHz, line-of-sight, up to 134Mbit/s)
802.16.2 (minimising interference between coexisting
WMANs.)
802.16a-2003 (2-11 Ghz, Mesh, non-line-of-sight)
802.16b-2004 (5-6 Ghz)
802.16c (detailed system profiles)
802.16e-2005 (Mobile Wireless MAN) – called Mobile
WiMAX
802.16m-2011, data rates of 100 Mbit/s mobile & 1 Gbit/s
fixed (4G)
802.16-2012, 16p, 16n, current
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Standar
Primary Radio
Family
d
Use
Tech
Downlink Uplink
Notes
(Mbit/s) (Mbit/s)
IEEE 802.16m
expected to offer
128 (in
56 (in
MIMOpeak rates of at
Mobile
20MHz
20MHz
WiMAX 802.16
SOFDM
least 1 Gbit/s fixed
Internet
bandwidth bandwi
A
speeds and
)
dth)
100Mbit/s to mobile
users.
LTE
LTE-Advanced
100 (in
50 (in expected to offer
OFDMA/
UMTS/ General
20MHz
20 MHz peak rates up to 1
MIMO/S
GSM
4G
bandwidth bandwi Gbit/s fixed speeds
C-FDMA
)
dth)
and 100 Mb/s to
mobile users.
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Purpose of WiMAX
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Providing mobile broadband connectivity across
cities and countries through a variety of devices.
Providing a wireless alternative to cable and
DSL for "last mile" broadband access.
Providing data, telecommunications (VoIP) and
IPTV services.
Providing a source of Internet connectivity as
part of a business continuity plan.
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Fixed and Mobile WiMAX
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Fixed WiMAX is optimised for home/office
networks
Mobile WiMAX is optimised for mobiles
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http://www.conniq.com/InternetAccess_WiMAX-02.htm
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Fixed WiMAX Architecture
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WiMAX as cellular alternative
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WiMAX as a mobile voice and data network is
potentially exponentially more efficient (profitable)
than the legacy cellular infrastructure
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WiMAX Architecture
MIB – Management Information Base
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802.16 protocol
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802.16 protocol stack

802.16 covers data link and physical layer
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802.16 MAC Sublayer Protocol
Classes of service
1. Constant
bit rate service.
2. Real-time variable bit rate service.
3. Non-real-time variable bit rate service.
4. Best-effort service.
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Physical layer (PHY)
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PHY cont.
BPSK: 1 bit/baud
 QPSK: 2 bits/baud
 QAM-16: 4 bits/baud
 QAM-64: 6 bits/baud
 Example: a 25 MHz bandwidth, QPSK can
deliver 50 Mbps, QAM-16 100 Mbps,
QAM-64 150 Mbps

Baud (Bd): measure of the symbol rate; the number of distinct symbolic
changes (signalling event) made to the transmission medium per second in
a digitally modulated signal
25 Bd means that 25 symbols are transmitted per second.
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PHY cont.
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TDD (time-division duplex)
- use same bandwidth for uplink and downlink
- controlled by timing
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FDD (frequency-division duplex)
- use different frequency for uplink and downlink
OFDM (orthogonal frequency-division
multiplexing)
- enhancement of frequency division multiplexing (FDM)
- maximise use of bandwidth
Also Adaptive Antenna Support (AAS) and MIMO
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TDD and FDD
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Figure 16.5: Frame structure at the physical layer (TDD)
In each time slot, a frame is in the air. The base
station fills the data to send to substation in the
downstream subframe; the substations fill the data to
send to the base station in the upstream subframe.
16.21
OFDM
FDM
OFDM
OFDM uses bandwidth which is not available for use in
FDM
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WiMAX Antennas
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Omni directional antenna
Omni directional antennas
are used for point-tomultipoint configurations.
its energy is greatly
diffused in broad-casting
360 degrees
This limits its range and
ultimately signal strength
good for situations where
there are a lot of
subscribers located very
close to the base station
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Sector antennas
focusing the beam in
a more focused area
offers greater range
and throughput with
less energy
Many operators will
use sector antennas
to cover a 360-degree
service area rather
than use an omni
directional antenna
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Panel antennas
a flat panel of about one foot
square
often used for point-to-point
applications
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Frequency Plan
By reusing
frequencies at
different base
stations, a WiMAX
operator can avoid
interference from
their own network
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WiMAX vs Wi-Fi
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WiMAX vs Wi-Fi cont.
WiMAX is designed to cover large area
(multiple homes/buildings), while Wi-Fi is to
cover small area (a home/building)
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Comparison of WiMAX, WiFi and 3G technology
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WiMAX applications
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Broadband Internet
Multimedia
IP multimedia subsystem (IMS)
Cellular Alternative
A clear alternative to connect areas without preexisting physical cable or telephone networks or
just areas without BB access
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Broadband Internet
• Fixed WiMAX is substitute for T1
• Mobile WiMAX has larger coverage than WiFi
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WiMax in UK
Freedom4′s WiMAX Licence Sold For
£12.5m. June 29, 2010.

UK Broadband, a subsidiary of PCCW (owned by
Hong Kong Telecom) Freedom4 (formerly Pipex
Wireless) had the necessary spectrum to launch
these wireless networks in the UK, but only
Freedom4 opted to do so with a WiMax network in
Milton Keynes and Stratford Upon Avon. These
WiMax networks were up and running in real world
situations years before LTE arrived on the scene.
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http://www.eur
opanetwork.com/
wimax/
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Why did LTE beat WiMax
UK Broadband’s chief executive, Nicholas James
http://www.ukbroadband.com/
 Most WiMax backers, including Clearwire in the United States (which
has already built WiMax networks in many US cities), have signalled
their intent to move across to LTE. It was never cost effective for WiMax
networks to compete effectively against fixed-line broadband networks.
 What happened was that LTE came along early enough so that all
operators adopted it,” said James. “No one adopted 16m because there
were no economies of scale. Indeed, all WiMax operators have signalled
they will move to LTE.
 WiMax is dead as a mobile technology but it is not dead as a fixed
technology.
 UK Broadband brought Freedom4′s spectrum, because it is adjacent
to UKB’s spectrum. “We now have 124MHz of LTE”
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Sprint will KILL OFF WiMax in
2015
Third-ranked US mobile network Sprint appears to
be poised to kill off its implementation of its lessregarded 4G technology, WiMax. The spectrum it
frees up will all move to LTE.
http://www.theregister.co.uk/2014/10/06/spr
int_wimax_to_close_in_2015/
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Number of WiMAX subscriber worldwide from 2010
to 2014 (in millions)
http://www.statista.com/statistics/277656/number-of-wimax-subscriber-worldwidesince-2010/
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Reference
Tannenbaum “Computer Networks”
 Stallings “wireless communications &
Networks”
 Frank Ohrtman: “Wimax overview”:
http://www.wimax.com/education/wimax/wi
max_overview
 “The 802.16 WirelessMAN™ MAC: It’s
Done, but What Is It?” (2001-11-12)
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