Wimax Is Defined As Worldwide Interoperability For Microwave Access by The
Wimax Is Defined As Worldwide Interoperability For Microwave Access by The
Wimax Is Defined As Worldwide Interoperability For Microwave Access by The
1.INTRODUCTION
Another way to get broadband to rural communities is the way many folks get their TV:
satellite, which offers download speeds of about 500 Kbps —faster than a modem, but
at best half as fast as DSL — through a satellite dish. But you really, really have to want
it. The system costs $600 to start, then $60 a month by the services provided by
DIRECWAY in the US.
The WiMAX technology provides a wireless connectivity efficiently; it is
essentially a technology solution to create wireless WAN and is meant to provide high-
speed Internet and that is the real advantage of WiMAX.
As a technology WiMAX is growing rapidly. And due to the ease with which it
can be deployed and maintained, it has the potential to become a unifying technology
for rural and metro regions.
2.WHAT IS WIMAX?
WiMAX technology involves microwaves for the transfer of data wirelessly. It can be
used for high-speed, wireless networking at distances up to a few miles. The term
WiMAX comes from 'Wireless (Wi) Microwave Access (MA).' WiMAX is very similar
to Wi-Fi in that it uses the same core technology of wireless modulation developed way
back in the '60's and '70's, called OFDM (Orthogonal Frequency Division
Multiplexing).
WiMAX combines the familiarity of Wi-Fi with the mobility of cellular that will deliver
personal mobile broadband that moves with you. It will let you get connected to the
Internet, miles from the nearest Wi-Fi hotspot. Soon, Mobile WiMAX will blanket large
areas—
metropolitan, suburban, or rural—delivering mobile broadband Internet access at speeds
similar to existing broadband.
WiMAX is built for the future with advanced, efficient wireless technology that
provides higher speeds than today’s wide area wireless technologies. It will be able to
completely transform your mobile Internet lifestyle, enabling you to connect in ways
you’ve only dreamed about.
3.WIMAX INFRASTRUCTURE
station to another base station area, similar to roaming enabled by Cellular phone
companies. Several topology and backhauling options are to be supported on the
WiMax base stations wire line backhauling (typically over Ethernet), microwave Point-
to-Point connection, as well as WiMax backhaul. With the latter option, the base station
has the capability to backhaul itself. This can be achieved by reserving part of the
bandwidth normally used for the end-user traffic and using it for backhauling purposes.
So how does WiMAX transmit the Internet over the landscape? The WiMAX network
uses an approach that is similar to that of cell phones.Coverage for a geographical area
is divided into a series of overlapping areas called cells. Each cell provides coverage for
users within that immediate vicinity. When you travel from one cell to another, the
wireless connection is handed off from one cell to another.
The WiMAX network includes two key components: a base station and a subscriber
device. The WiMAX base station is mounted on a tower or tall building to broadcast the
wireless signal. The subscriber receives the signals on a WiMAX enabled notebook,
mobile Internet
device (MID), or even a WiMAX modem.
The basic idea in WiMAX is to use high transmit power and focused signals,
using directional antennas. The base standard operates in the 10 GHz to 60 GHz range.
Thus, the risk of interference is very limited. Theoretically, a signal channel can provide
data rates of up to 100 Mbps on both uplink and downlink. Operators can use multiple
channels and provide bandwidths up to 350 Mbps. This significantly higher than all the
existing Wi-Fi and cellular technologies, which can, at best, provide 100 Mbps.
The base standard is meant to be a fixed wireless access for point-to-multipoint (PMP)
connections. This means that a single WiMAX base station will be able to connect
either an ISP or a public telephone network situated over a distance of 50 km. This also
means that a single base station is able to distribute traffic to many subscriber stations
that are either placed on rooftops or even indoors. PMP uses a scheduling mechanism
that yields a high efficiency since stations transmit only their slots, thereby avoiding
contention among stations. In addition to PMP, WiMAX also supports mesh mode
networking, in which subscriber stations communicate directly with each other. This
reduces the need for line of sight (LOS), as well as deployment costs.
IEEE 802 refers to a family of IEEE standards dealing with local area networks and
metropolitan area networks. More specifically, the IEEE 802 standards are restricted to
networks carrying variable-size packets. (By contrast, in cell-based networks data is
transmitted in short, uniformly sized units called cells. Isochronous networks, where
data is transmitted as a steady stream of octets, or groups of octets, at regular time
intervals, are also out of the scope of this standard.) The number 802 was simply the
next free number IEEE could assign, though “802” is sometimes associated with the
date the first meeting was held — February 1980.
6.OBJECTIVES
The WiMax standard has been developed with many objectives in mind. These are
summarized below:
support the trenching of cables is not required. Operators that have obtained
licenses to use
one of the licensed bands, or that plan to use one of the unlicensed bands, do not
need
to submit further applications to the Government. Once the antenna and
equipment
are installed and powered, WiMax is ready for service. In most cases,
deployment of
WiMax can be completed in a matter of hours, compared with months for other
solutions.
drive costs down dramatically, and the resultant competitive pricing will provide
considerable cost savings for service providers and end-users.
• Wider Coverage: WiMax dynamically supports multiple modulation levels,
including BPSK, QPSK, 16-QAM, and 64-QAM. When equipped with a high-
power amplifier and operating with a low-level modulation (BPSK or QPSK, for
example),WiMax systems are able to cover a large geographic area when the
path
between the BS and the SS is unobstructed.
• Non-Line-of-Sight Operation: NLOS usually refers to a radio path with its first
Fresnel zone completely blocked. WiMax is based on OFDM technology, which
has the inherent capability of handling NLOS environments. This capability
helps WiMax products deliver broad bandwidth in a NLOS environment, which
other wireless product cannot do.
• High Capacity: Using higher modulation (64-QAM) and channel
bandwidth(currently 7 MHz, with planned evolution towards the full bandwidth
specified in the standards), WiMax systems can provide significant
7.SYSTEM DEVELOPMENT
shorthand term for IEEE Standard 802.16, also known as "Air Interface for Fixed
Broadband Wireless Access Systems." . The initial version of the 802.16 standard,
approved by the New York-based IEEE in 2002, operates in the 10-to-66-GHz
frequency band and requires line-of-sight towers.
The IEEE 802.16 designed to operate in the 10-66 GHz spectrum and it specifies the
physical layer (PHY) and medium access control layer (MAC) of the air interface BWA
systems. At 10-66 GHz range, transmission requires Line-of-Sight (LOS).IEEE 802.16
is working group number 16 of IEEE 802, specializing in point-to-multipoint broadband
wireless access.
The IEEE 802.16 standard provides the foundation for a wireless MAN industry.
However, the physical layer is not suitable for lower frequency applications where non-
line-of-sight (NLOS) operation is required [2]. For this reason, the IEEE published
802.16a standard to accommodate NLOS requirement in April 2003. The standard
operates in licensed and unlicensed frequencies between 2 GHz and 11 GHz, and it is an
extension of the IEEE 802.16standard.The IEEE 802.16 Working Group created a new
standard, commonly known as WiMax, for broadband wireless access at high speed and
low cost, which is easy to deploy, and which provides a scalable solution for extension
of a fiber-optic backbone.
WiMax base stations can offer greater wireless coverage of about 5 miles, with LOS
(line
of sight) transmission within bandwidth of up to 70 Mbps.
WiMax is supported by the industry itself, including Intel, Dell, Motorola, Fujitsu,
AT&T, British Telecom, France Telecom, Reliance Infocomm, Siemens, Sify,Price
Warehouse Coopers and Tata Teleservices – forming an alliance called WiMax Forum.
It represents the next generation of wireless networking [3]. WiMAX original release
the 802.16standard addressed applications in licensed bands in the 10 to 66 GHz
frequency range. Subsequent amendments have extended the 802.16 air interface
standard to cover non-line of sight (NLOS) applications in licensed and unlicensed
bands in the sub 11 GHz frequency range.
Filling the gap between Wireless LANs and wide area networks, WiMAX-compliant
systems will provide a cost-effective fixed wireless alternative to conventional wire-line
DSL and cable in areas where those technologies are readily available. And more
importantly the WiMAX technology can provide a cost-effective broadband access
solution in areas beyond the reach of DSL and cable. The ongoing evolution of IEEE
802.16 will expand the standard to address mobile applications thus enabling broadband
access directly to WiMAX-enabled portable devices ranging from smart phones and
Pads to notebook and laptop computers.
Factors beyond equipment cost (e.g., installation, roof rights, backhaul, spectrum costs)
were significant contributors to the poor economics of the high-frequency multipoint
systems. In early 2000, work on a low-frequency (<11 GHz) revision of the 802.16
standard was begun by the IEEE working group. This revision (designated 802.16a)
incorporated new radio link system options more suitable for low-frequency service
while maintaining most of the access control system specifications of the original
standard Completed in January 2000, the 802.16a standard included features
supporting:
• Non-line-of-sight service capability
• Multiple radio modulation options (single carrier, OFDM)
• Licensed and unlicensed band implementations
Versatile access control and QoS features, including TDM and packet services,
advanced security A corrected and modified version of 802.16a (designated 802.16-
REVd) was completed in June 2004. Initial WiMAX profiles are a subset of the 802.16-
REVdstandard. A mobile extension to the low-frequency 802.16 standard is now being
developed by the IEEE 802.16e working group. This extension will support delivery of
broadband data to a moving wireless terminal, such as a laptop computer with an
integrated WiMAX modem being used by a passenger on a commuter train. The
WiMAX Forum expects to endorse a mobile profile following completion of the
802.16e standard.
OFDM
OFDM breaks a signal into many independent pieces before transmitting it across the
airwaves in order to increase spectral efficiency. By diversifying the signal in this way,
even if some of the pieces don’t make it through, the signal can still be reconstructed on
the other end.
Orthogonal Frequency Division Multiplexing (OFDM) is a multiplexing technique that
subdivides the bandwidth into multiple frequency sub-carriers , In an OFDM system,
the input data stream is divided into several parallel sub-streams of reduced data rate
(thus increased symbol duration) and each sub-stream is modulated and transmitted on a
separate orthogonal sub-carrier. The increased symbol duration improves the robustness
of OFDM to delay spread.
Although the fundamental technology is the same, over time we can add levels of
sophistication to WiMAX. Wi-Fi channels occupy a fixed width of the spectrum. But
with WiMAX, we're going to enable the traffic lanes – or channels – to get smaller and
narrower. This helps service providers seeking to offer wireless last-mile DSL or cable-
type service because they can provide a narrower channel that uses less bandwidth and
serve more users. You can take what used to be a fixed Wi-Fi lane and make a bunch
more lanes and serve more people.
The other big difference between Wi-Fi and WiMAX – starting right away – is that
we're going to use licensed spectrum to deliver WiMAX. To date, all Wi-Fi technology
has been delivered in unlicensed spectrum. WiMAX will use one of the unlicensed
frequencies, but we're also supporting two other frequencies that are licensed. What that
means is that you can turn up the output power and broadcast longer distances. So
where Wi-Fi is something that is measured in hundreds of feet, usually WiMAX will
have a very good value proposition and bandwidth up to several miles. Also WiMAX is
designed to be a carrier-grade technology, which requires a higher level of reliability
and quality of service than are now available in typical Wi-Fi implementations. Those
fundamental differences make WiMAX more of a metropolitan area access technology
versus hotspot.
WiMAX operates on the same general principles as WiFi -- it sends data from one
computer to another via radio signals. A computer (either a desktop or a laptop)
equipped with WiMAX would receive data from the WiMAX transmitting station,
probably using encrypted data keys to prevent unauthorized users from stealing access.
The fastest WiFi connection can transmit up to 54 megabits per second under optimal
conditions. WiMAX should be able to handle up to 70 megabits per second. Even once
that70 megabits is split up between several dozen businesses or a few hundred home
users,
it will provide at least the equivalent of cable-modem transfer rates to each user.
The biggest difference isn't speed; it's distance. WiMAX outdistances WiFi by miles.
WiFi'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. Of course, at that distance, terrain, weather and large buildings
will act to reduce the maximum range in some circumstances, but the potential is there
to cover huge tracts of land.
WiMax is not designed to clash with WiFi, but to coexist with it. WiMax coverage is
measured in square kilometers, while that of WiFi is measured in square meters. 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 WiFi range (up to 5GHz
maximum). But 802.16a added support for 2-11 GHz frequency also[4]. One WiMax
base station can be accessed by more than 60 users. WiMax can also provide
broadcasting services also. WiMax specifications also provides much better facilities
than WiFi, 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.
WiMax will allow the interpenetration for broadband service provision of VoIP, video,
and internet access – simultaneously. WiMax can also work with existing mobile
networks. WiMax antennas can "share" a cell tower without compromising the function
of cellular arrays already in place.
10.1 Fixed
The IEEE 802.16-2004 standard (which revises and replaces IEEE 802.16a and
802.16REVd versions) is designed for fixed-access usage models. This standard may be
referred to as ―fixed wireless‖ because it uses a mounted antenna at the subscriber’s
site. The antenna is mounted to a roof or mast, similar to a satellite television dish. IEEE
802.16-2004 also addresses indoor installations, in which case it may not be as robust as
in outdoor installations. The 802.16-2004 standards is a wireless solution for fixed
broadband Internet access that provides an interoperable, carrier-class solution for the
last mile. The Intel WiMAX solution for fixed access operates in the licensed 2.5-GHz,
3.5-GHz and license-exempt 5.8-GHz bands. This technology provides a wireless
alternative to the cable modem, digital subscriber lines of any type (xDSL),
transmit/exchange (Tx/Ex) circuits and optical carrier level (OC-x) circuits.
10.2Portable
The IEEE 802.16e standard is an amendment to the 802.16-2004 base specification and
targets the mobile market by adding portability and the ability for mobile clients with
IEEE 802.16e adapters to connect directly to the WiMAX network to the standard. The
802.16e standard is expected to be ratified in early 2005.
The 802.16e standard uses Orthogonal Frequency Division Multiple Access (OFDMA),
which is similar to OFDM in that it divides the carriers into multiple sub carriers.
OFDMA, however, goes a step further by then grouping multiple sub carriers into sub-
channels. A single client or subscriber station might transmit using all of the sub-
channels within the carrier space, or multiple clients might transmit with each using a
portion of the total number of sub-channels simultaneously.
The IEEE 802.16-2004 standard improves last-mile delivery in several key aspects:
• Multi-path interference
• Delay spread
• Robustness
Multi-path interference and delay spread improve performance in situations where there
is not a direct line-of-sight path between the base station and the subscriber station.
The emerging 802.16-2004 media-access control (MAC) is optimized for long-distance
links because it is designed to tolerate longer delays and delay variations. The 802.16
specification accommodates MAC management messages that allow the base station to
query the subscriber station, but there is a certain amount of time delay.
11.WIMAX IN INDIA
The Pune Municipal Corporation (PMC) has plans to cover 400 sq kilometres of
the city with wireless connectivity. The project, “Unwired Pune”, will make use of a
combination of both the WiMAX and Wi-Fi technologies. It is expected to be
completed by 2007.
The recently merged Alcatel-Lucent alliance has decided to utilize India for
manufacturing broadband and WiMAX equipment through a transfer of technology and
contract manufacturing arrangement with state-owned ITI. This will happen at the ITI
plant at Naini in Uttar Pradesh.
Intel plans to start WiMAX trials in the next few months in several cities across
India including in Mumbai, Delhi, Bangalore and Pune, the Daily News & Analysis
reports.
12.WIMAX WORLD
The list of countries which have the WiMAX technology deployed in their country
are as follows:
Australia, Austria, Azerbaijan, Brazil, Canada, Chile, Congo,Costa Rica, Croatia,
Denmark, Estonia, Finland, France, Georgia, Italy, India, New
Zealand,Nigeria,Paraguay, Russia, Slovakia, South Africa, United
Kingdom,Ukraine,USA
Austria:
Azerbaijan:
AZQTEL holds the 3.5 GHz license in Azerbaijan, and is deploying in Baku, Q1 of
2007, and a nationwide rollout throughout 2007.
Costa Rica:
QTEL has deployed a national long-haul backbone throughout the entire country.
They are converting last mile access from older point-to-point systems to WiMAX
beginning Q2 of 2007.
Korea:
Russia:
Synterra WiMAX uses Nextnet Wireless' (acquired by Motorola on Aug 29, 2006)
equipment for its WiMAX network in Moscow region. Synterra holds 2.5-2.7GHz
license valid until 2015. Unlimited Internet access plans start from $85 US per
month.
13.ADVANTAGES OF WIMAX
3. Connecting Wi-Fi hotspots with each other and to other parts of the Internet.
4. Providing a wireless alternative to cable and DSL for last mile (last km)
broadband access.
DISADVANTAGE OF WIMAX
1. It is widely believed that mobile operators will initially deploy 4G very slowly,
relying on their EV-DO or HSPA networks to provide for more ubiquitous
coverage.
2. Initial investment is very high & Investment in existing infrastructure should be
raised.
3. There are security concerns, since the data travels through air and not over wires
also the 802.11 security specification is not well implemented by the IEEE.
4. Availability of licensed spectrum.
14.APPLICATIONS OF WIMAX
Connecting Wi-Fi hotspots with each other and to other parts of the
Internet.
Providing a wireless alternative to cable and DSL (Digital Subscriber
Line) for last mile (last km) broadband access.
Providing high-speed mobile data and telecommunications services (4G).
Providing a diverse source of Internet connectivity as part of a business
continuity plan. That is, if a business has a fixed and a wireless internet
connection they are unlikely to be affected by the same service outage.
Providing Nomadic connectivity.
WiMax& IPTV : The third leg of the triple play is Internet Protocol
Television (IPTV). IPTV enables a WiMax service provider to offer the
same programming as cable or satellite TV service providers.
WiMax VoIP : A fixed wireless solution not only offers competitive
internet access, it can do the same for telephone service thus further
bypassing the telephone company's copper wire network. Voice over
Internet Protocol (VoIP) offers a wider range of voice services at reduced
cost to subscribers and service providers alike
15.CONCLUSION
The latest developments in the IEEE 802.16 group are driving a broadband wireless
access (r)evolution thanks to a standard with unique technical characteristics. In
parallel, the WiMAX forum, backed by industry leaders, helps the widespread adoption
of broadband wireless access by establishing a brand for the technology. Initially,
WiMAX will bridge the digital divide and thanks to competitive equipment prices, the
scope of WiMAX deployment will broaden to cover markets where the low POTS
penetration, high DSL unbundling costs, or poor copper quality have acted as a brake on
extensive high-speed Internet and voice over broadband. WiMAX will reach its peak by
making Portable Internet a reality. When WiMAX chipsets are integrated into laptops
and other portable devices, it will provide high-speed data services on the move,
extending today's limited coverage of public WLAN to metropolitan areas. Integrated
into new generation networks with seamless roaming between various accesses, it will
enable end users to enjoy an "Always Best Connected" experience. The combination of
these capabilities makes WiMAX attractive for a wide diversity of people: fixed
operators, mobile operators and wireless ISPs, but also for many vertical markets and
local authorities. Alcatel, the worldwide broadband market leader with a market share in
excess of 37%, is committed to offer complete support across the entire investment and
operational cycle required for successful deployment of WiMAX services.
16.REFERENCES
[1] Vaughan-Nichols SJ, ―Achieving Wireless Broadband with WiMax―, IEEE
Computer Vol. 37, Issue 6, June 2004.
[2] Fourty N.; Val T.; Fraisse P.; Mercier J.-J, ―Comparative Analysis of New High
Data Rate Wireless Communication Technologies from Wi-Fi to Wimax―,
Proceedings of Joint International Conference on Networking and Services (ICAS/ICNS
2005), 2005.
[3] Alavi H.S.; Mojdeh M.; Yazdani N., ―A Quality of Service Architecture for IEEE
802.16 Standards―, 2005 Asia –Pacific Conference on Communications, Perth,
Australia, October 2005.
[4] Michel Barbeau, ―WiMax/802.16 Threat Analysis‖. Proceedings of the 1st ACM
International Workshop on Quality of Service & Security in Wireless and Mobile
Networks, Q2SWinet ’05, October 2005.
[5] Ghosh A.; Wolter D.R.; Andrews J.G.; Chen R., ―Broadband Wireless Access
WiMax/802.16: Current Performance Benchmarks and Future Potential‖ IEEE
Communications Magazine, Feb 2005.