WIMAXWIMAX

BY

SHASHI JAKKU

Contents Introduction Working of WIMAX IEEE 802.16 standard 802.16 Architecture IEEE 802.16 Specifications Features of WIMAX Advantages of WIMAX over WIFI WIMAX vs. 3G ISSUES in WIMAX vs. 3G FUTURE OF WIMAX

What is WIMAX?

WIMAX stands for Worldwide Interoperability for Microwave Access

WiMAX refers to broadband wireless networks that are based on the IEEE 802.16 standard, which ensures compatibility and interoperability between broadband wireless access equipment

WiMAX, which will have a range of up to 31 miles, is primarily aimed at making broadband network access widely available without the expense of stringing wires (as in cable-access broadband) or the distance limitations of Digital Subscriber Line.

THINK OF INTERNET There are three possible ways to

access internet. Broadband access

Uses DSL or cable modem at home and T1 or T3 line at office

WIFIUses WIFI routers at home and hotspots on the road

Dial Up Connection

NEW TECHNOLOGY

Broadband access is too expensive and WiFi coverage is very sparse.

The new technology promises High speed of broadband service Wireless rather than wired access Broad Coverage

1) 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 3,000 square miles (~8,000 square km). 2) A WiMAX receiver - The receiver and antenna could be a

small box or Personal Computer Memory card, or they could be built into a laptop the way WiFi access is today

A WIMAX system consists of

WIMAX TOWER WIMAX RECEIVER

HOW WIMAX works?

MODES OF OPERATION

Non-Line of sightUses a lower frequency range.

Line of sightUses a higher frequency range.

WIMAX Scenario Consider a scenario where a WiMax-enabled computer is

10 miles away from the WiMax base station.

A special encryption code is given to computer to gain access to base station

The base station would beam data from the Internet required for computer (at speeds potentially higher than today's cable modems)

WIMAX Scenario The user would pay the provider monthly fee for using

the service. The cost for this service could be much lower than current high-speed Internet-subscription fees because the provider never had to run cables

The WiMAX protocol is designed to accommodate several different methods of data transmission, one of which is Voice Over Internet Protocol (VoIP)

If WiMAX-compatible computers become very common, the use of VoIP could increase dramatically. Almost anyone with a laptop could make VoIP calls

WIMAX CHIPS

WiMAX Mini-PCI Reference Design Intel’s first WIMAX chip

IEEE 802.16

Range- 30 miles from base station Speed- 70 Megabits per second Frequency bands- 2 to 11 and 10 to

66(licensed and unlicensed bands respectively)

Defines both MAC and PHY layer and allows multiple PHY layer specifications

IEEE 802.16 Specifications 802.16a

Uses the licensed frequencies from 2 to 11 GHzSupports Mesh network

802.16b Increase spectrum to 5 and 6 GHzProvides QoS( for real time voice and video service)

802.16c Represents a 10 to 66GHz

802.16d Improvement and fixes for 802.16a

802.16eAddresses on MobileEnable high-speed signal handoffs necessary for

communications with users moving at vehicular speeds

802.16 Architecture IEEE 802.16 Protocol Architecture has 4 layers: Convergence, MAC,

Transmission and physical, which can be mapped to two OSI lowest

layers: physical and data link.

802.16 Architecture

P2MP ArchitectureBS connected to Public Networks

BS serves Subscriber Stations (SS)Provides SS with first mile access to Public

Networks

Mesh ArchitectureOptional architecture for WiMAX

P2MP Architecture

Mesh Architecture

FEATURES OF WIMAX

Scalability

Quality of Service

Range

Coverage

Scalability The 802.16 standard supports flexible radio

frequency (RF) channel bandwidths.

The standard supports hundreds or even thousands of users within one RF channel

As the number of subscribers grow the spectrum can be reallocated with process of sectoring.

Quality of Service Primary purpose of QoS feature is to

define transmission ordering and scheduling on the air interface

These features often need to work in conjunction with mechanisms beyond the air interface in order to provide end to end QoS or to police the behaviour or SS.

Requirements for QoS A configuration and registration function to pre

configure SS based QoS service flows and traffic parameters

A signalling function for dynamically establishing QoS enabled service flows and traffic parameters

Utilization of MAC scheduling and QoS traffic parameters for uplink service flows

Utilization of QoS traffic parameters for downlink service flows

RANGE

Optimized for up to 50 Km Designed to handle many users

spread out over kilometres Designed to tolerate greater multi-

path delay spread (signal reflections) up to 10.0μ seconds

PHY and MAC designed with multi-mile range in mind

Coverage

Standard supports mesh network topology

Optimized for outdoor NLOS performance

Standard supports advanced antenna techniques

BENEFITS OF WIMAX

Speed Faster than broadband service

Wireless Not having to lay cables reduces cost Easier to extend to suburban and rural areas

Broad Coverage Much wider coverage than WiFi hotspots

Benefits to Service Providers Allow service providers to deliver high

throughput broadband based services like VoIP, high-speed Internet and Video

Facilitate equipment compatibility Reduce the capital expenditures required for

network expansion Provide improved performance and extended

range

Benefits to Customers

Range of technology and service level choices from both fixed and wireless broadband operators

DSL-like services at DSL prices but with portability

Rapidly declining fixed broadband prices No more DSL “installation” fees from

incumbent

Why not WIFI

Scalability Relative Performance Quality of Service Range Coverage Security

Scalability

• Channel bandwidths can be chosen by operator (e.g. for sectorization)

• 1.5 MHz to 20 MHz width channels. MAC designed for scalability. independent of channel bandwidth

• MAC designed to support thousands of users.

• Wide (20MHz) frequency channels

• MAC designed to support 10’s of users

802.16a802.11

5.0 bps/Hz100 Mbps1.5 – 20 MHz802.16a

2.7 bps/Hz54 Mbps20 MHz802.11

Maximum bps/Hz

Maximum Data Rate

Channel Bandwidth

RELATIVE PERFORMANCE

Quality of Service

• Grant-request MAC

• Designed to support Voice and Video from ground up

• Supports differentiated service levels: e.g. T1 for business customers; best effort for residential.

• Centrally-enforced QoS

• Contention-based MAC (CSMA/CA) => no guaranteed QoS

• Standard cannot currently guarantee latency for Voice, Video

• Standard does not allow for differentiated levels of service on a per-user basis

• 802.11e (proposed) QoS is prioritization only

802.16a802.11

Range

• Optimized for up to 50 Km

• Designed to handle many users spread out over kilometers

• Designed to tolerate greater multi-path delay spread (signal reflections) up to 10.0μ seconds

• PHY and MAC designed with multi-mile range in mind

• Optimized for ~100 meters

• No “near-far” compensation

• Designed to handle indoor multi-path delay spread of 0.8μ seconds

• Optimization centers around PHY and MAC layer for 100m range

802.16a802.11

Coverage

• Optimized for outdoor NLOS performance

• Standard supports mesh network topology

• Standard supports advanced antenna techniques

• Optimized for indoor performance

• No mesh topology support within ratified standards

802.16a802.11

Security

• Existing standard is PKM - EAP• Existing standard is WPA + WEP

• 802.11i in process of addressing security

802.16a802.11

Advantages of WiMax over 3G

Using an assortment of proprietary and standards-based technologies, such as OFDM and W-CDMA ,WiMax has a clear advantage over 3G

The advantages include Higher Throughput Low Cost Lower Latency

Advantages of WiMax over 3G

Advantages of WiMax over 3G

WiMax spectrum is more economical than 3G. The price paid per Hz is as much as 1000

times lower than for 3G spectrum

The low cost is a clear driver for service providers to enter the field of wireless services with WiMax

Advantages of WiMax over 3G WiMAX is important for mobile broadband

wireless, as it completes 3G by providing higher performance for data with more than 1 Mbps downstream to allow connection of laptops and PDAs

WiMAX technology is the solution for many types of high-bandwidth applications at the same time across long distances and will enable service carriers to converge the all-IP-based network for triple-play services data, voice, and video

Advantages of WiMax over 3G WiMAX interoperable solutions enable

economies of scale through integration of standard chipsets, making WiMAX Forum Certified products cost-effective at delivering high-capacity broadband services at large coverage distances in Line Of Sight and Non Line Of Sight conditions

USES OF WIMAX

More ……

FUTURE

WiMax will be deployed in three stages In the first phase WiMaX technology (based on IEEE

802.16-2004) provides fixed wireless connections In the second phase WiMaX will be available as a

cheap and self-installing Subscriber Terminal (ST), linked to PC and to antenna

The third phase enables portability, thus WiMAX (based on IEEE 802.16e) will be integrated into commercial laptops

Promises

ISSUES in 3G vs. WIMAX

Deployment of the network WIMAX deployment is in the planning

stages and it might take 3-5 years in providing reasonable coverage in well populated areas

WiMax may initially be relegated to college campuses and larger corporate campuses where people are less mobile and costs containment is important

ISSUES in 3G vs. WIMAX

Quality of Service To provide quality of service by deploying WIMAX

networks and to facilitate the continuous availability of service, careful planning is required at the edge of the network to manage network monitoring, availability, failover, routing etc

This can actually be done using outsourced services in cheap labor markets like India and China via the

public Internet

ISSUES in 3G vs. WIMAX

Cost Issue The main reason to opt for WIMAX is its low cost.

The price paid per Hz for WIMAX spectrum is as much as 1000 times lower than for 3G spectrum

The low cost of WIMAX spectrum compared to 3G is a clear driver for service providers to enter the field of

wireless services with WIMAX

The WIMAX Forum Founded in April 2001

No Profit organization comprised of wireless access system manufacturers, component suppliers, software developers and carriers

A wireless industry consortium that supports and promotes WiMAX’s commercial usage

Comply with the WiMAX standard and focus on the interoperability

Members include Intel, AT&T, Siemens Mobile, British Telecommunications, etc

Conclusion (The Final Issue) Will WIMAX replace 3G?

Along with the forthcoming standardization, WiMAX has the potential to substitute 3G and become a promising 4G

WiMAX has its distinct identity as either a stand-alone solution for incumbent and competitive fixed network operators or as complementary radio access solution for established 2G and 3G cellular network operators

Fixed-line operators, on the one hand, may consider WiMAX as a viable alternative to add mobility to the service portfolio, leveraging their huge subscriber base, in particular in countries where 3G licensing is delayed or not

affordable

References www.ewh.ieee.org/r4/chicago/Yu-WiMAX.pdf

http://computer.howstuffworks.com/wimax.htm

www.wimaxforum.org

http://standards.ieee.org/catalog/olis/lanman.html

Questions?