By Shah Ankur Vasant Wi MAX WIMAX stands

By, Shah Ankur Vasant

Wi. MAX • WIMAX stands for Worldwide Interoperability for Microwave Access • The original IEEE 802. 16 standard (now called "Fixed Wi. MAX") was published in 2001. • Wi. MAX adopted some of its technology from Wi. Bro, a service marketed in Korea • Its a communication technology for wirelessly delivering highspeed Internet service to large geographical areas ØGeographical Area Coverage: 30 miles ØBandwidth: 75 Mbps ØFrequency bands- 2 to 11 and 10 to 66 Ghz(licensed and unlicensed bands respectively) ØDefines both MAC and PHY layer

Wi. Max Over Wi-Fi Coverage Area: Below 100 m for Wi-Fi Scalability Supports around 10 users Bitrate: 54 Mbps in 20 Mhz Channels Cost For Laying Cables throughout.

802. 16 Standards 802. 16 (Now withdrawn) - 2001 • basic 802. 16 standard released in 2001, provided high data links at 11 and 60 GHz frequencies. 802. 16 a (Now withdrawn) - 2003 • Uses licensed frequencies from 2 to 11 GHz • Supports Mesh Network 802. 16 b (Now withdrawn) • Frequencies between 5 and 6 GHz • Provided Quality of Service(Qo. S).

802. 16 c (Now Withdrawn) -2002 • Provided a system profile for operating between 10 and 66 GHz and provided more details for operations within this range • Aim was to enable greater levels of interoperability. 802. 16 d (802. 16 -2004 or Fixed Wi. MAX) • • • Major revision of the 802. 16 standard Resulted in withdrawal of all previous standards Improvements to 802. 16 a including the use of 256 carrier OFDM Only addressed fixed operation. High Data Rates of 75 Mbps 802. 16 e (802. 16 -2005 or Mobile Wi. MAX) • For nomadic and mobile use • Lower data rates of 15 Mbps • Enables full nomadic and mobile use including handover

Types Of Wi. MAX Wireless access can be divided into three classes • Stationary • Pedestrian • Vehicular 802. 16 Standards is classified into two types of usage models • Fixed Wi. MAX • Mobile Wi. MAX

IEEE 802. 16 -2004 • Current Standard for using fixed Wi. Max • 3. 5 GHz and 5. 8 GHz frequency bands • Frequency division duplexing (FDD) • Time division duplexing (TDD) IEEE 802. 16 e - 2005 • extension to the 802. 16 -2004 • supports mobile communications • 2. 3 and 2. 5 GHz frequency bands.

802. 16 d 802. 16 e Spectrum Below 11 GHz Below 6 GHz Bit Rate Up to 75 Mbps @ 20 MHz Channel Up to 15 Mbps @ 5 MHz Channel Modulation OFDM 256 Sub-Carrier QPSK, 16 QAM, 64 QAM Scalable OFDMA Mobility Fixed and Mobile Channel Bandwidth Selectable Channel Bandwidths between 1. 25 -20 MHz 2. 3 - 5 MHz Cell Radius 3 -5 Miles Depends on tower height, power etc. 1 -3 Miles

A WIMAX system consists of 1. Wi. MAX Base Station (BS) • Base Station is similar to a cellphone tower and Covers A radius of 30 miles(3000 Sq. Ft) 2. Wi. MAX receiver (Wi. MAX CPE) • Customer Premise Equipment • Receiver could be a small box or PCMCIA card, or they could be built into a laptop

Fixed Wi. MAX

Wi. MAX Network Architecture • P 2 P Point to Point • P 2 MP Point to Multi Point • Mesh Network

P 2 P and P 2 MP

Mesh

Modes Of Operation Non-Line-Of-Sight : • Wi. Fi sort of service, where a small antenna on your computer connects to the tower • uses a lower frequency range -- 2 GHz to 11 GHz • Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract or bend around obstacles. Line-Of-Sight : • • • fixed dish antenna points straight at the Wi. MAX tower from a rooftop or pole stronger and more stable Allows to send a lot of data with fewer errors Uses High Frequencies, ranges reaching 66 Mhz Less Interference and More Bandwidth

Protocol Layers Of Wi. MAX 802. 16 Protocol Architecture has 4 layers: Convergence, MAC, Transmission and physical, which can be map to two OSI lowest layers: physical and data link OSI Data Link Layer OSI Physical Layer Convergence Medium Access Control Transmission Physical

Protocol Architecture MAC Protocol: Convergence sub-layer: • Handle the higher-layer protocols Common part sub-layer: • Channel access, connection establishment and maintenance & Qo. S Security sub-layer: • Authentication, secure key exchange and encryption Physical and transmission layer functions: • Encoding/decoding of signals • Preamble generation/removal • Bit transmission/reception

Physical Layer Features: • • • Frequency Band Channel Bandwidth MIMO FDD/TDD Signal Modulation: Data Link Layer Features: • • • access protocol, security and session establishment functions.

Wi. MAX PHY Frame

Features Of Wi. MAX • • Scalability Quality of Service Range Coverage

Advantages of Wi. MAX • Faster than broadband service • No need to lay cables thus reducing cost • Easier to extend to Sub-Urban and rural areas • Much Wider coverage • Can use licensed spectrum • Provides data, telecommunication services and portability.

Disadvantages • Lack of Quality • Low bit rate over Long distance • Speed of connectivity • Sharing of bandwidth • Wi. Max over Wi-Fi • Expensive network • Bad Weather • Power consuming

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