Download - Wi-Fi and Wi-max
Wi-Fi and WiMax
Presented By,S.J.
VIT University, Chennai.
Both the technology
- work on wireless networks.- have their own standards specified by IEEE.
The evolution of wireless LAN started with the introduction of the 802.11b standard in 1999.
In the same year, the 802.11a started introduced the Orthogonal Frequency Division Multiplexing (OFDM).
In 2003, "the best" of both standards were joined to the 802.11g standard
Wi-MAX was standardized as 802.16 by Wi-MAX forum, in 2001.
Standard’s Overview
Wi-Fi is wireless networking technology that uses
radio waves to provide wireless high-speed Internet and network connections.
A common misconception is that the term Wi-Fi is short for "wireless fidelity," however this is not the case. Wi-Fi is simply a trademarked phrase that means IEEE 802.11x.
It is wireless LAN technology which provides narrow range of connectivity.
Establishes a standard for interoperability and backward compatibility.
Wi-Fi Overview
Wi-Fi technology used ratio technologies that
transmits and receive data at high speed. Standards specified by IEEE.
•IEEE 802.11b•IEEE 802.11a
•IEEE 802.11g•IEEE 802.11n
Wi-Fi’s-IEEE standard
Comparison of Wi-Fi
Standards
Introduced in 2009. Improve network throughput over 802.11a and
802.11g 300 Mbps speed. Multi input and multiple output (MIMO) added. 40MHz channel to the PHY, and frame
aggregation to the MAC layer. 2.4/5GHz radio frequencies.
IEEE 802.11n
AP based technology (Infrastructure mode)
Peer-to-Peer technology (Ad-Hoc mode)
Point-to-Multipoint Bridge topology.
Wi-Fi Network Architecture
Wi-Fi setup contains one or more
access point and client AP broadcasts SSID via beacons, every 100ms. Beacons transmitted at 1Mbps. Client can communicate at least at 1Mbps. Connections to AP(same SSID) is decided on basis
of signal strength. Connection criteria and roaming is open to client. Wi-Fi has same properties as that of non switched
Ethernet network.
How Wi-Fi Works?
There are two signaling frequencies currently used by Wi-Fi
networks: 2.4 GHz - Comprises of
- 14 channels - bandwidth 20 to 22 MHz (ISM band)- Bluetooth, microwaves, telephones, garage door openers,
etc. 5 GHz - Comprises of
- 13 channels- bandwidth 20 MHz (U-NII band)- Less crowded as compared to 2.4GHz.
The "Wi-Fi CERTIFIED" trademark can only be used by Wi-Fi products range of about 20 meters in indoor and greater at outdoor. It uses WEP, WPA, WPA2
Salient Features
Convenience Mobility Productivity Deployment Expandability Cost
Advantages
Security Range Reliability Speed
Disadvantages
WIMAX is an IP based, wireless broadband access
technology that provides performance similar to 802.11/Wi-Fi networks with the coverage and QOS of cellular networks.
WI-MAX refers to “Worldwide Interoperability for Microwave Access”.
It is wireless MAN technology which provides broadband range of connectivity.
A standard based technology that enable the delivery of last mile wireless broadband access as an alternative to cable and DSL
Establishes standard that provides fixed and mobile Internet Access.
Wi-MAX Overview
Standards specified by IEEE.
•IEEE 802.16•IEEE 802.16a
•IEEE 802.16e
Wi-MAX’s-IEEE standards
Comparison of Wi-MAX
standards
Wi-MAX Architecture
When a user send data from a subscriber device to a base station then
that base station broadcast the wireless signal into channel which is called uplink and base station transmit the same or another user is called downlink.
The base station of WiMAX has higher broadcasting power, antennas and enhanced additional algorithms.
When signal transmit form user to WiMAX base station or base to user (WiMAX receiver) the wireless channel faces many attenuation such as fraction, reflection, refraction, wall obstruction etc.
OFDMA that prohibit interfering and be multiplexed also makes possible power prioritization for various sub carriers according to the link quality.
WiMAX is providing quality of service (WiMAX QoS) which enables high quality of data like VoIP or TV broadcasts.
WiMAX technology support various protocol such as VLAN, ATM, IPv4 Ethernet etc.
How Wi-MAX works
Two forms of wireless services
Non line of Sight. Line of Sight.
OFDM based physical layer Very high field data rates-74Mbps Scalable bandwidth(1.25,5,10MHz) and data rate Adaptive modulation and coding. Link Layer retransmission. Robust Security. Support for advance antenna techniques
Salient Features
Single station can serve hundreds of users. Much faster deployment of new users
comparing to wired networks. Speed of 10 Mbps at 10 kilometers with line-
of-site. It is standardized, and same frequency
equipment should work together.
Advantages
Line of site is needed for longer connections Weather conditions like rain could interrupt
the signal. 0ther wireless equipment could cause
interference. Multiplied frequencies are used. WiMAX is very power intensive technology and
requires strong electrical support. Big installation and operational coast.
Disadvantages
Yota is the largest WiMAX network operator in the
world. By the end of 2008 there were 350,000 WiMAX
subscribers in Korea. As of October 2010, the WiMAX Forum claimed
over 592 WiMAX networks deployed in over 148 countries, covering over 621 million subscribers.
By February 2011, the WiMAX Forum cited coverage of over 823 million people, and estimate over 1 billion subscribers by the end of the year.
Current Deployments
Comparison Between Wi-Fi and WiMAX
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