Fixed WiMAX

By,Shah Ankur Vasant

• WIMAX stands for Worldwide Interoperability for Microwave Access

• The original IEEE 802.16 standard (now called "Fixed WiMAX") was published in 2001.

• WiMAX adopted some of its technology from WiBro, a service marketed in Korea

• Its a communication technology for wirelessly delivering high-speed Internet service to large geographical areas

Geographical Area Coverage: 30 miles Bandwidth: 75 Mbps

Frequency bands- 2 to 11 and 10 to 66 Ghz(licensed and unlicensed bands respectively)

Defines both MAC and PHY layer

WiMAX

WiMax Over Wi-Fi

Coverage Area:Below 100m for Wi-Fi

ScalabilitySupports around 10 users

Bitrate:54 Mbps in 20 Mhz Channels

CostFor Laying Cables throughout.

802.16 (Now withdrawn) - 2001

• basic 802.16 standard released in 2001,provided high data links at 11 and 60 GHz frequencies.

802.16a (Now withdrawn) - 2003

• Uses licensed frequencies from 2 to 11 GHz• Supports Mesh Network

802.16b (Now withdrawn) • Frequencies between 5 and 6 GHz• Provided Quality of Service(QoS).

802.16 Standards

802.16c (Now Withdrawn) -2002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.

802.16d (802.16-2004 or Fixed WiMAX)

• Major revision of the 802.16 standard• Resulted in withdrawal of all previous standards• Improvements to 802.16a including the use of 256 carrier

OFDM• Only addressed fixed operation.• High Data Rates of 75 Mbps

802.16e (802.16-2005 or Mobile WiMAX)

• For nomadic and mobile use• Lower data rates of 15 Mbps• Enables full nomadic and mobile use including handover

Wireless access can be divided into three classes• Stationary• Pedestrian• Vehicular

802.16 Standards is classified into two types of usage models

• Fixed WiMAX•Mobile WiMAX

Types Of WiMAX

IEEE 802.16-2004•Current Standard for using fixed WiMax• 3.5 GHz and 5.8 GHz frequency bands• Frequency division duplexing (FDD) • Time division duplexing (TDD)

IEEE 802.16e - 2005• extension to the 802.16-2004• supports mobile communications• 2.3 and 2.5 GHz frequency bands.

802.16d 802.16e

Spectrum Below 11 GHz Below 6GHz

Bit RateUp to 75Mbps @ 20MHz

ChannelUp to 15Mbps @ 5MHz

Channel

ModulationOFDM 256 Sub-Carrier QPSK,16QAM,64QAM

Scalable OFDMA

Mobility Fixed Fixed and Mobile

Channel BandwidthSelectable Channel

Bandwidths between 1.25-20MHz

2.3 - 5 MHz

Cell Radius3-5 Miles

Depends on tower height, power etc.

1-3 Miles

1. WiMAX Base Station (BS) • Base Station is similar to a cellphone tower and Covers A radius of 30miles(3000 SqFt)

2. WiMAX receiver (WiMAX CPE)• Customer Premise Equipment• Receiver could be a small box or PCMCIA card, or they could be built into a laptop

A WIMAX system consists of

Fixed WiMAX

• P2P Point to Point

• P2MP Point to Multi Point

• Mesh Network

WiMAX Network Architecture

P2P and P2MP

Mesh

Non-Line-Of-Sight : • WiFi 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 WiMAX 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

Modes Of Operation

Protocol Layers Of WiMAX

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

Convergence

Medium Access Control

Transmission

Physical

OSI Data Link Layer

OSI Physical Layer

MAC Protocol:Convergence sub-layer:

• Handle the higher-layer protocols Common part sub-layer:

• Channel access, connection establishment and maintenance & QoS

Security sub-layer:• Authentication, secure key exchange and encryption

Physical and transmission layer functions:• Encoding/decoding of signals• Preamble generation/removal• Bit transmission/reception

Protocol Architecture

Physical Layer Features:• Frequency Band• Channel Bandwidth• MIMO• FDD/TDD• Signal Modulation:

Data Link Layer Features:• access protocol,• security and• session establishment functions.

WiMAX PHY Frame

• Scalability• Quality of Service• Range• Coverage

Features Of WiMAX

• 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.

Advantages of WiMAX

• Lack of Quality

• Low bit rate over Long distance

• Speed of connectivity

• Sharing of bandwidth

• WiMax over Wi-Fi

• Expensive network

• Bad Weather

• Power consuming

Disadvantages

QUESTIONS ??