2. Contents
• Typical network ranges
• What is WiMAX
• Data rate vs Mobility
• WiMAX Structure
• Key Features of WiMAX
• Prior Attempts: LMDS and MMDS
• Spectrum option and Effect of frequency
• IEEE 802.16 and its features
• OFDM subcarriers and sub channelization
• WiMAX vs LTE comparison
• Summary

3. Wi-Fi vs WiMAX

4. Typical Network Ranges

5. What is WiMAX ?
• Wireless over long distances
• Acronym for Worldwide Interoperability for Microwave Access.
• It is a wireless Internet service designed to cover wide geographical
areas serving large number of users at low cost
• WiMAX is technically based on “IEEE 802.16” standard
• The name "WiMAX" was created by the WiMAX Forum, which was
formed in June 2001 to promote conformity and interoperability of the
standard.

6. What is WiMAX ?

7. What is WiMAX ?
• WiMAX uses microwave radio technology to connect
computers to the internet in place of wired connections such as
DSL or cable modems
• WiMAX is combination of Wi-Fi and Cellular Networks
• Wi-Fi gives you the high data rate and Cellular network gives
you the mobility

9. Key Features of WiMAX
• WiMAX doesn’t works on fixed band like cellular networks (900 MHz), Wi-
Fi on 2.4GHz, etc.
• It works many bands 2.3GHz, 2.5GHz, 3.5GHz,……etc.
• Most of the standard before this has fixed bandwidth like cellular networks,
Wi-Fi(802.11-20MHz)
• Scalable i.e. can use any available spectrum width: 1.25MHz to 28MHZ
• Open Technology like Wi-Fi not like Cellular networks
• Reach and mobility like cellular but much higher data rates
• High data rate, up to 70 Mbps
• Long distance. up to 50 Kms
• Mobility, up to 120 to 150 Km/hr
• Data rate vs. Distance trade off using Adaptive Modulation: 64 QAM to
BPSK
• Offers Non Line of Sight (NLOS) operation

10. Prior Attempts :LMDS & MMDS
• Local multipoint Distribution service(1999)
– 28GHz band
– Affected by Rain
• Multichannel Multipoint Distribution Service(2000)
– 2.5 to 2.7 GHz band
– Not affected by Rain
– LOS Antennas
• Both of these things avoided by WiMAX(2001-2010)

11. WiMAX
• WiMAX ≠ IEEE 802.16
• World Wide Interoperability for Microwave Access
• 420+ including semiconductor companies, equipment
vendors, integrators, service providers, Like Wi-Fi Alliance
• WiMAX forum standardize the products and check their
interoperability
• http://www.wimaxforum.org/

12. In India frequencies 2.5 to 2.69 GHz, 3.4 to 3.6 GHz, 2.3 to 2.4 GHz and 700 MHz
used

13. Effect of Frequency
• Higher Frequencies have higher attenuation
– So we can go shorter distances
• Higher Frequencies need smaller antennas
• Higher frequencies are more affected by weather
• Higher frequencies have more bandwidth and higher data rates
• Higher frequencies allows more Frequency Reuse as attenuate close
to cell boundaries. Low frequencies propagate far

14. IEEE 802.16 improvements
Function Frequency
Band
Carrier Duplexing
Wireless MAN SC P-to-P LOS 10 – 66
GHz
Single TDD
FDD
Wireless MAN SC
16a
P-to-P LOS 2 – 11 GHz
Licensed
Single TDD
FDD
Wireless MAN
OFDM 16d
P-to-MP LOS 2 – 11 GHz
Licensed
256 TDD
FDD
Wireless MAN
OFDM 16e
P-to-MP NLOS 2 – 11 GHz
Licensed
2048 TDD
FDD

15. IEEE 802.16 Features
• Scalable OFDM
• TDD and FDD
• Adaptive modulation and coding
• Space Time block codes
• Adaptive Antenna system

16. OFDM Subcarriers
• Data Subcarriers
• Pilot Subcarriers: Used for channel estimation.
• Guard carriers: At edges. They are not used but provided for
avoiding the spilling into the neighboring spectrum
• DC Subcarrier: At the center for frequency Band for reference
Interesting thing is that the data and pilot Subcarriers are not fixed
they rotate continuously

17. Subchannelization
• Sub channel = Group of subcarriers
• Each user is given one or more sub channel
• Subcarriers of sub channel are distributed and rotating. It is just
like Frequency Hopping
• Channels allotted to user based on SINR

18. WiMAX vs LTE
• WiMAX and LTE are both using a name 4G technology
• ITU-R specified requirements for the 4G standards called
IMT-Advanced specification.
– 100 Mbps for high mobility communication like cars and trains
– 1 Gbps for low mobility communication like pedestrians and stationary
mobile users
• Both WiMAX and LTE still don’t meet these requirements, but
they both use the name 4G

19. WiMAX and LTE Similarities
• They are both IP technologies
• They both support advanced MIMO – multiple input and
multiple output antenna technology
• They both use similar modulation technology based on
OFDM – orthogonal frequency division multiplexing

20. WiMAX vs LTE Differences
• LTE-A uses different channels bandwidth from 1.4 MHz to 100
MHz, while WiMAX uses channels bandwidths up to 40 MHz
• LTE uses different modulation for uplink (SC-FDMA) and downlink
(OFDMA), while WiMAX uses the same modulation for both uplink
and downlink – SOFDMA
• LTE-A can handle speeds up to 450 km/h or 280 mph, while
WiMAX 120 km/h or 75 mph
• WiMAX network doesn’t support legacy systems like 2G and 3G,
while LTE is compatible and enables coexistence and roaming
between LTE and 3G.

21. LTE Advantages over WiMAX
• LTE is compatible with previous mobile technologies –
GSM, GPRS, UMTS, EDGE, WCDMA, HSPA, CDMA-
one, CDMA2000, EV-DO, EV-DV and the synchronous
SC-CDMA
• Enables much greater speed for the mobile users – speed
up to 450 km/h or 250 mph
• Better technology for power consumption of mobile
terminals – it uses SC-FDMA for uplink – modulation
technology that saves battery life of mobile terminals

22. Summary
• WiMAX is Worldwide Interoperability for Microwave Access for
wide geographical area
• Based on IEEE 802.16 standards
• It uses Wi-Fi and cellular networks for its working
• One of the biggest advantages of LTE over WiMAX is its
compatibility with all previous mobile technologies GSM, GPRS,
UMTS, WCDMA, CDMA etc.
• It is also important to mention that the latest LTE standard, LTE –
Advanced or LTE-A, is the only true 4G technology

23. References
• http://www.eetimes.com/document.asp?doc_id=1163580
• http://www.wimaxforum.org/
• http://thebestwirelessinternet.com/wimax-vs-lte.html
• https://en.wikipedia.org/wiki/IEEE_802.16

24. Thank You !!!

25. Security Issue
• Every WiMAX traffic is encrypted using DES (Data Encryption
Standard) or AES (Advanced Encryption Standard) for securing its
transmission over the air.
• The encryption keys are distributed from the BS to the SSs using
PKM ( Privacy Key Management) protocol to ensure that only
authorized SSs can receive the keys.
• Every WiMAX user device is authenticated using a digital
certificate or SIM ( Subscriber Identity Module).
• This way, WiMAX keeps user traffic from eavesdropping and
protects operator or service provider from becoming a victim of
bandwidth theft by unauthorized users

26. The Conclusion of WiMAX vs LTE – Which 4G
Technology is Better
• The LTE is much more popular and widespread than WiMAX and I am
sure that the big majority of the mobile operators will chose the LTE as its
4G technology. One of the biggest advantages of LTE over WiMAX is its
compatibility with all previous mobile technologies GSM, GPRS, UMTS,
WCDMA, CDMA, CDMA200, EV-DO. WiMAX is compatible with the
previous version of WiMAX that were not used as mobile technologies. It
is also important to mention that the latest LTE standard, LTE – Advanced
or LTE-A, is the only true 4G technology.
• WiMAX is a better choice for the low cost installing network in developing
countries, wireless replacement for the DSL, private networks in dedicated
industrial segments.

27. Duplexing Scheme in WiMAX: TDD or FDD
• Duplexing refers to the way downlink and uplink data is arranged in a two-
way wireless transmission. The downlink carries information from a Base
Station (BS) to Subscriber Stations (SSs). Downlink is also known as
forward link. The uplink carries information from a SS to a BS. It is also
called reverse link. There are two types of duplexing scheme, i.e. FDD and
TDD.

28. THANK YOU