Computer Network presentation by Arun

1. BROADBAND
WIRELESS
802.16
PRESENTED BY :
ARUN GANGWAR
ME REGULAR (ECE)

2.  INTRODUCTION
 WHAT IS WIMAX
 FEATURES OF WIMAX
 WIMAX SYSTEM
 MODES OF OPERATION
• LOS
• NLOS
 802.16 STANDARDS
 THE 802.16 PROTOCOL STACK
• PHYSICAL LAYER
• MAC LAYER
 COMPARISON OF WIMAX WITH OTHER WIRELESS TECHNOLOGIES
• WIMAX Vs 3G
• WIMAX Vs WiFi
 WIMAX - SECURITY FUNCTIONS
 WIMAX ADVANTAGES AND DRAWBACKS
 APPLICATIONS
 FUTURE OF WIMAX
 SUMMARY
 REFERENCES
OUTLINE

3. What is Broadband Wireless?
 Broadband wireless is high-speed Internet service via wireless
technology, available in Internet cafés, local “hot spots” within many
cities, private businesses and many homes.
 The advantage of broadband wireless is that the computer receiving
the Internet signal need not be tethered by an Ethernet or network
cable to the broadband modem or router.
 A broadband wireless modem receives the service and transmits it via
radio waves to the immediate surrounding area.
 The most common way to take its advantage by using a laptop, with a
wireless broadband adapter, commonly available in a portable
computer (PC) card format.

4. Broadband Wireless
LIMITING FACTOR :
 In today’s world, a large number of wireless transmission
technologies exist.
 These technologies are distributed over different network families
depending upon the network scale such as PAN, WLAN, WMAN
and WAN.
 The rapid growth of internet and increasing interest in portable
computing devices are likely to push demand for high-speed wireless
data services with aggregated higher information bit rates.
 There are basically three limiting factors for transmitting high data
rate over the wireless medium that mainly include multipath fading,
delay spread and co-channel interference .
 Technologies that promise to deliver higher data rates are attracting
more and more vendors and operators towards them.

5. Broadband Wireless
SOLUTION :
 To address this issue a very interesting solution has been defined by
the IEEE 802.16 working group .
 WIMAX provides a 21st century platform for broadband wireless
access.
 WIMAX stands for worldwide interoperability for microwave
access .

6. WIMAX / IEEE 802.16
Wimax networks refer to broadband wireless networks that are
based on the IEEE 802.16 standard, which ensures compatibility
and interoperability between broadband wireless access
equipment .
 The IEEE 802.16 standards
define how wireless traffics
move between subscriber
equipment and core networks.
 WiMAX was designed for the
transmission of multimedia
services (voice, Internet, email,
games and others) at high data
rates.
Source: SHASHI JAKKU

7. Features
 Use microwave for the wireless transfer of data.
 Specifies a frequency band in the range between 2 GHz to 66 GHz.
 For high speed wireless networking.
 Basically, Wimax is a wireless internet service that is capable of
covering a wide geographical area by serving hundreds of users at a
very low cost.
 Uses OFDM ,good for multipath environments.
 It includes TDD and FDD duplexing support.
 Flexible channel sizes (3.5 MHz,5 MHz,10MHz)
 An easy and fast system to install.
 Leading to low installation cost, when compared to fiber ,cable or
DSL deployments.

8. Data Rate vs Mobility

9. 802.16 STANDARDS
 802.16.1 : (10-66 GHz, line-of-sight, up to
134Mbit/s).
 802.16.2 : (minimizing interference between
coexisting WMANs).
 802.16a : (2-11 Ghz, Mesh, non-line-of-
sight).
 802.16b : (5-6 Ghz).
 802.16c : (detailed system profiles).
 P802.16e : (Mobile Wireless MAN).

10. A WIMAX TOWER
 Similar in concept to a cell-phone tower - A single
WiMAX tower can provide coverage to a very large area
as big as ~8,000 square km.
A WIMAX CLIENT TERMINAL
 The terminal receiver and antenna could be a small box or
Personal Computer Memory card, or they could be built
into a laptop.
WIMAX System

11. WIMAX System

12. WiMAX
 WiMAX uses radio microwave technology to provide wireless
internet service to computers and other devices that are equipped
with WiMAX compatible chips for example PDA’s, cell phones
etc.
 It works more or less like cellular network technology.
 The theoretical range of WiMAX is up to 30 miles and achieves
data rates up to 75 Mbps
 WiMAX operates in similar manner as Wi-Fi but with two very
convincing differences as compared to Wi-Fi, these are :
o Data rate
o Data range

13. MODES OF OPERATION
WiMax can provide 2 forms of wireless service:
 LOS.
 NLOS.

14. NLOS
 These create multiple signals that
will arrive at a receiver at different
times, from different paths, and
with different strength.
 Wireless systems developed for
NLOS environment have to
incorporate a number of
techniques to overcome this
problem and that make the systems
more complex than those for LOS.
 Wi-Fi sort of service, where a small antenna on a computer connects to the
tower.
 Uses lower frequency range (2 to 11 GHz).
 Non-line-of-sight (NLOS) is a condition where a signal from a wireless
transmitter passes several obstructions before arriving at a wireless
receiver. The signal may be reflected, refracted, diffracted, absorbed or
scattered.

15. LOS
 Where a fixed antenna points straight at the WiMax tower from a rooftop
or pole.
 The LOS connection is stronger and more stable.
 Higher throughput.
 Uses higher frequencies: reaching a possible 66 GHz.
 Through stronger LOS antennas, higher range can be achieved: up to 50km
radius.
 Line-of-sight (LOS) is a condition where a signal travels over the air
directly from a wireless transmitter to a wireless receiver without passing
an obstruction.
 LOS is an ideal condition for a wireless transmission because the
propagation challenge only comes from weather or atmospheric parameters
and the characteristic of its operating frequency.

16. 802.16 Standards History
802.16a
(Jan 2003)
IEEE 802.16a (January 2003)
• Extension for 2-11 GHz
• Targeted for non-line-of-sight,
• Point-to-Multi-Point applications “LAST MILE”
broadband access.
802.16
(Dec 2001)
IEEE 802.16 (2001)
• Original fixed wireless broadband air Interface for
10 – 66 GHz.
• Connection-oriented, TDM/TDMA MAC
• Targeted for Line-of-sight only
• Point-to-Multi-Point applications
802.16c
(2002)
IEEE 802.16c (2002)
Represents a 10 to 66 GHz
system profile that standardizes
more details of the technology.
802.16d
(802.16-2004)
(Oct 2004)
IEEE 802.16d (Oct 2004)
• Combines both IEEE 802.16 and 802.16a
• Some modifications to the MAC and PHY
802.16e
(802.16-2005)
(Dec 2005)
IEEE 802.16e (2005)
• MAC/PHY Enhancements to support subscribers
moving at vehicular speeds.

17. 802.16 Standards
IEEE 802.16 IEEE
802.16a/802.16d
IEEE 802.16e
Completed Dec 2001 Oct 2004 Dec 2005
Spectrum 10 - 66 GHz 2 – 11 GHz 2 - 6GHz
Application Backhaul Wireless DSL and
Backhaul
Mobile Internet
Channel Conditions Line of Sight Only Non-Line of Sight Non-Line of Sight
Bit Rate 32 – 134 Mbps Up to 75 Mbps Up to 15 Mbps
Modulation QPSK,16QAM and
64QAM
OFDM ,QPSK,16QA
M,
64QAM
OFDMA
Channel Bandwidths 20,25 and 28 MHz 1.5 and 20 MHZ Same as 802.16d

18. WiMAX : Technology
Wide
Coverage Mobility
SLA
Portable
Flexible
Architecture
Low Cost
High
Capacity
High
Security
Quick
Deployment
QoS
WiMAX
The WiMAX standard has been developed with many objectives in mind

19. Why wimax is necessary?
 DSL and cable modems
 No mobility.
 Huge infrastructure investment
 Cellular systems
 Fundamentally designed for voice
 Poor spectral efficiency
 Wi-Fi/802.11
 No mobility support
 Short range
 Not a broadband technique on its own

20. WHY WIMAX NECESSARY ? CONT..
 Wimax /802.16
 Variable and potentially large bandwidth.
 Efficient exploitation of diversity.
 Time (Scheduling ,adaptive modulation)
 Frequency (Scheduling ,adaptive modulation)
 Space (Space codes , MIMO)
 Packet switched architecture.

21. WIMAX CHIPS

22. DEPLOYMENT SCENARIOS
 IEEE 802.16/WiMAX technology intends to provide broadband
connectivity to both fixed and mobile users in a wireless
metropolitan area network (WMAN) environment. To provide
flexibility for different applications, the standard supports two major
deployment scenarios.
Last-mile BWA:
 In this scenario, broadband wireless connectivity is provided to
home and business users in a WMAN environment.
 The operation is based on a point-to-multipoint single hop
transmission between a single base station (BS) and multiple
subscriber stations (SSs).

23. DEPLOYMENT SCENARIOS
Backhaul networks :
 This is a multihop (or mesh) scenario where a WiMAX network
works as a backhaul for cellular networks to transport data/voice
traffic from the cellular edge to the core network (Internet).
 Backhaul is a technology that is linked with carrying traffic among
circulated sites.
 Wimax backhaul is getting data from one point and spreading it over
a network with high data rates and low price.
 Uses OFDMA (Orthogonal Frequency Division Multiple Access).
 It is specially designed for Wide Area Network with higher
throughput.
 Another very unique feature of Wimax backhaul is that it gives
protection against theft of services.

24. DEPLOYMENT SCENARIOS
Coverage range up to 50km and speeds up to 70Mbps(shared among users).

25. The 802.16 Protocol Stack

26. The 802.16 Physical Layer(1/3)
Physical and transmission layer functions:
• Encoding/decoding of signals
• Preamble generation/removal
• Bit transmission/reception
• The PHY converts MAC layer frames into signals to be transmitted
across the air interface.
• Traditional narrow band radio is used with conventional modulation
schemes.
 QPSK: (longer distance)
 QAM-16: (medium distance)
 QAM-64: (short distance)

27. The 802.16 Physical Layer(2/3)

28. The 802.16 Physical Layer(3/3)
 802.16 provides a more flexible way to allocate the bandwidth.
 Two schemes are used
o FDD
o TDD

29. The 802.16 MAC Layer
 The primary task of the WiMAX MAC layer is to provide an
interface between the higher transport layers and the physical layer.
 The MAC layer takes packets from the upper layer,these packets are
called MAC service data units (MSDUs) and organizes them into
MAC protocol data units (MPDUs) for transmission over the air.
 The 802.16 MAC is designed for point-to-multipoint (PMP)
applications and is based on collision sense multiple access with
collision avoidance (CSMA/CA).

30. Mac features
The MAC incorporates several features suitable for a broad range of
applications at different mobility rates, such as the following:
 Privacy key management (PKM) for MAC layer security.
 Broadcast and multicast support.
 High-speed handover and mobility management primitives.
 Three power management levels, normal operation, sleep and idle.
 Header suppression, packing and fragmentation for efficient use of
spectrum.
 Support for integrated voice/data connections.

31. The WiMAX MAC
The WiMAX MAC comprises three sublayers
ATM, Ethernet,
Internet Protocol
Packing,
Fragmentation,
ARQ, QoS
Autentication,
Key Exchange,
Privacy (encrypt.)
Convergence
sublayer
MAC Common
part sublayer
Security
sublayer

32. Convergence sublayer
 The service specific convergence sublayer (CS) provides any
transformation or mapping of external network data, received
through the CS service access point (SAP) into MAC SDUs
received by the MAC CPS through the MAC SAP.
 Accepting higher layer protocol data units (PDUs) from the higher
layer
 Performing classification of higher layer PDUs.
 Associating them to the proper service flow identified by the
connection identifier (CID).
 Delivering CS PDUs to the appropriate MAC SAP.

33. MAC Common part sublayer
 Defines multiple-access mechanism
 Bandwidth allocation
 Connection establishment
 Connection maintenance
 Connection-oriented protocol
 Assign connection ID to each service flow.

34. Security sublayer
 Deals with privacy and security.
 The security sublayer provides subscribers with privacy or
confidentiality across the broadband wireless network.
 It manages :
 Authentication
 Secure key exchange
 Encryption

35. The 802.16 MAC Frame Format
Each MAC packet consists of the three components,
1) A MAC header
which contains frame control information.
2) A variable length frame body
which contains information specific to the frame type.
3) A frame check sequence (FCS)
which contains an IEEE 32-bit cyclic redundancy code (CRC)

36. The 802.16 Frame Structure
A GENERIC FRAME
36

37. The 802.16 Frame Structure
 HT(Header type): For generic frame,HT=0
 EC (Encryption control)
o 0 = Payload is not encrypted or payload is not included.
o 1 = Payload is encrypted.
 Type : This field identifies the frame type ,whether packing and
fragmentation is present.
 CI (CRC indicator)
o 1 = CRC is included .
o 0 = No CRC is included.
 EKS (Encryption key sequence) : Which encryption key is used.
 Length: Complete length of the frame including header.
 Connection ID: Which connection this frame belongs to.
 Header CRC: Header check sequence. An 8-bit field used to detect errors in
the header.Header check-sum using 100000111.
 ESF(Extended subheader) ESF=0 ,absent:ESF=1.present

38. The 802.16 Frame Structure
BANDWIDTH REQUEST (BR) HEADER

39. The 802.16 Frame Structure
 The second header type ,for frames that request bandwidth.
 HT(Header type): HT=1
 EC (Encryption control)= 0,Payload is not encrypted or payload is
not included.
 BR field indicate the number of bytes requested,or telling how much
bandwidth is needed to specified number of bytes.
 Bandwidth request frames do not carry a payload or full frame CRC.

40. Fragmentation and packing
 Packing
The MAC layer may pack multiple MAC SDUs into one single
MAC PDU. When the radio channel is relatively good, this allows a
better use of available resources.
 Fragmentation
MSDU might be fragmented by the transmitter to form several
MPDUs. The advantage of fragmentation is to lower the risk of
losing a whole MSDU to the risk of losing part of it, a fragment.
This is interesting when the radio channel is relatively bad or
packets too long.

41. IEEE 802.16 MAC – MAC SDU Fragmentation
FEC block
1
OFDM
symbol
1
PHY Burst
Pre.
MAC SDU
OFDM
symbol
n1
......
FEC FEC Block
m1
......
MAC SDU
seg-1
HT CRC
MAC PDU Payload
HT CRC
MAC PDU
Payload
A MAC SDU can be fragmented into multiple segments, each
segment is encapsulated into one MAC PDU
FEC block
1
OFDM
symbol
1
PHY Burst
Pre.
OFDM
symbol
n2
......
FEC Block
m2
......
HT CRC
MAC PDU
Payload
MAC SDU
seg-2
MAC SDU
seg-3
F
S
H
F
S
H
Fragmentation
Sub-Header
(8 bits)
F
S
H

42. IEEE 802.16 MAC – MAC SDU Packing
MAC
SDU 1
Fixed size MSDUs, e.g., ATM
Cells, on the same connection
HT CRC
MAC PDU Payload
HT CRC
Packing with fixed size MAC SDUs (no packing sub-header is needed)
......
PSH
MAC
SDU 2
MAC
SDU k
Packing with variable size MAC SDUs (Packing Sub-Heade is neeeded)
PSH ...... PSH
MAC SDU or
seg. 1 MAC SDU or seg 2
MAC SDU or
seg n
Variable size
MSDUs or MSDU
segments, e.g.,
IP packets, on
the same
connection
Packing
Sub-Heder
(16 bits)

43. Spectrum Influence in WiMAX Network
 The best advantage of WiMAX system is that, it can operate in both
license and license free frequency bands which helps for global
deployment of WiMAX and have certain advantages over the wired
network.
 Channel bandwidth which increases the capacity of the WiMAX
network by reusing the frequency.

44. WiMAX License Spectrum
 Most of the country around the world uses 2.5 GHz band as a
license frequency band for WiMAX application.
 Since allocation of spectrum varies among country to country, so
spectrum allocation can varies between 2.6 to 4.2 GHz.
 It can effectively deliver point-to-multipoint spectrum to large
number of users.
 It has strong bandwidth capacity.
 It is also good for interference free services and better QoS.

45. WiMAX Unlicensed Spectrum
 The globally available unlicensed spectrum is 2.4 GHz Industrial,
Scientific and Medical band (ISM).
 Unlicensed spectrum is better for lower cost network deployment
in rural areas, developing countries, emerging markets and
developed countries with underdeveloped areas.
 It is also good for quickly deployed the services rather that
wasting time for the license permit.
 It can be used in a point to point (PTP) communication in a small
population area or a point-to-multipoint (PMP) communication in
a rural areas or a place like college campus, where interference
can be controlled .

46. Comparison of WiMAX with Other Wireless
Technologies
When WiMAX was taken into consideration for replacing the DSL
and cable modems and providing an enhanced solution to the exiting
solution (802.11 standards), no one thought that WiMAX could be
so strong and powerful that it could replace or even proves to be a
good competitor for 3G and beyond cellular networks.

47. A Comparison of WiMAX & 3G
 Introduces OFDMA, which improves spectrum efficiency around
two times more than current 3G technologies.
 Enables a wide range of advanced antenna systems including MIMO,
space-time coding and spatial multiplexing. It thus increases the
covering range of WiMAX .
 WiMAX spectrum is more economical than 3G.
 Higher Throughput.
 Low Cost.
 Lower Latency.

48. A Comparison of WiMAX & Wifi
 The fastest Wi-Fi connection can transmit up to 54 megabits per
second under optimal conditions. WiMAX should be able to handle
up to 70 megabits per second.
 WiMAX outdistances Wi-Fi by miles. Wi-Fi's range is about 100
feet (30 m). WiMAX will blanket a radius of 30 miles (50 km) with
wireless access. The increased range is due to the frequencies used
and the power of the transmitter .
 The original WiMAX standard (IEEE 802.16) proposes the usage of
10-66 GHz frequency spectrum for the WiMAX transmission,
which is well above the Wi-Fi range (up to 5 GHz maximum).

49. A Comparison of WiMAX & Wifi
 WiMAX specifications also provides much better facilities than Wi-
Fi, providing higher bandwidth and high data security by the use of
enhanced encryption schemes.
 WiMAX can also provide service in both Line of Sight (LOS) and
Non-Line of Sight (NLOS) locations, but the range will vary
accordingly.

50. COMPARISION TABLE

51. WiMAX - Security Functions
Security is handled by a privacy sublayer within the WiMAX MAC. The key
aspects of WiMAX security are as follow:
Support for privacy:
 User data is encrypted using cryptographic schemes.
 WiMAX uses the Advanced Encryption Standard (AES) to produce
cipher text.
 The cipher text is then transmitted over the wireless network and cannot
be understood by an eavesdropper.
Device/user authentication:
 WiMAX provides a flexible means for authenticating users to prevent
unauthorized use.
Support for fast handover:
 A three-way handshake scheme is supported to optimize the
reauthentication mechanisms for supporting fast handovers.

52. advantages of WiMAX
Long Range: Perhaps the most significant advantage of WiMAX
over other wireless technologies is the range it provides. WiMAX has a
communication range of up to 30 miles. This is enough to cover a medium
size city.
Higher Bandwidth: Before WiMAX, the existing wireless
technologies have various issues that are mostly related to the bandwidth.
WiMAX provides high data rates which makes.
Low cost: Although the cost to install a WiMAX base station would
be around 20,000 $ but still it would be much less cheaper when it comes
to the deployment of wireless network.
Security : Security options of Wimax Technology also offer very
high security because of encryption system used by Wimax.

53. advantages of WiMAX
 Multi - functionality within Wimax
Technology : Wimax Technology perform a variety of task at a
time such as offering high speed internet, providing telephone service,
transformation of data, video streaming, voice application etc.
 Wimax Coverage : The single station of Wimax can operate
and provide coverage for hundred of users at a time and manage sending
and receiving of data at very high speed with full of network security.
 Wimax Infrastructure : Wimax infrastructure is very easy
and flexible therefore it provides maximum reliability of network.

54. Disadvantages
 WiMAX is basically a power sensitive technology, meaning that it
heavily relies on strong electrical support.
 A Line of sight is required in order to make a wireless data
communication connection extending over 6 miles or more.
Means it is needed for more distant connections.
 Bandwidth is shared among users in a given radio sector. If there
are many users in one sector, they will have lower speed.
 Bad weather conditions such as rain could interrupt the signal.
 Other wireless equipment could cause interference.
 WiMAX is a very power-consuming.

55. APPLICATION
Broadband Internet access real time applications
 Video streaming
 VoIP, Video on Demand
 Video Conference
 Surveillance and monitoring (forests, volcano, etc.)
Other possible real time complex applications
 E-learning
 General applications and services based on IP connectivity.

56. Applications
FIGURE SHOWS THE APPLICATIONS OF WIMAX TO PROVIDE INTERNET ACCESS
OVER BIG GEOGRAPHICAL AREA.

57. APPLICATIONs
Security:
 This is crucial for telemedicine services. Patient information must
be communicated in a secure and reliable manner. The MAC layer
security feature in the IEEE 802.16/WiMAX standard can provide
access control and encryption functionalities for wireless
telemedicine services.
WiMAX-based wireless telemedicine network.

58. APPLICATIONs

59. APPLICATIONS

60. FUTURE OF WIMAX
 Along with the forthcoming standardization, WiMAX has the
potential to substitute 3G and become a promising 4G.
 WiMax is a technology which considered as the first step toward
4G. Today WiMax is operating as second generation and third
generation technology but in near future it would be substantial 4G
technology.
 It is expected that WiMax becomes the dominant standard for
Wireless MAN in the world market, at least, in fixed broadband
networks.
 WiMAX networks can provide very-high-speed wireless
connectivity in presence of mobility.

61. 802.16– WiMAX
Leading BWA Standards –IEEE 802.16m
BT
ZigBee
Wireless Broadband

62. REFERENCES
• Andrew S. Tanenbaum “Computer Networks” fourth edition ;prentice hall of
India 2005.
• IEEE 802.16-2004 (802.16REVd)
• IEEE 802.16-2005 (802.16e)
• “IEEE Standard 802.16: A Technical Overview of the Wireless MAN Air
Interface for Broadband Wireless Access,” C. Eklund et al., IEEE
Communication Magazine, June 2002
• WiMAX Forum: www.wimaxforum.com
• http://en.wikipedia.org/wiki/WiMax
• www.goingwimax.com (www.goingwimax.com)
• http://www.broadband.gov/fieldevents/fh_public_safety/pavlak.ppt
• http://www.broadband.gov/docs/ws_tech_fixed_bb/ws_technology_fixed_broa
db

63. REFERENCES
• http://www.itr-rescue.org/bin/pubdocs/mtg-weekly/9-16-
05%2520Karim%2520Hassib%2520-%2520WiMAX.pp
• http://www.ieee-
centennial.org/Speaker_Notes/20050216_Wireless_Broadband_IEEE.pp
• http://www.novarum.com/documents/Novarum1H2007Overview.pdf
IEEE Std 802.16e-2005, “IEEE Standard for Local and Metropolitan Area
Networks Part 16: Air Interface for Fixed and Mobile Broadband Wireless
Access Systems,” IEEE Std 802.16e-2005, February 2006.
• Changazi, S.() UWiMAX 802.16e and Its Comparison with Other 3G
TechnologiesU , Advanced Telecommunication ETS190.

64. Thank you.