wimax

Contents Ways of Access Internet Why We Use Wimax. What is Wimax Wimax Working Wimax Architecture Wimax Interfaces Wimax relationship with other technologies Wimax Standards Wimax Advantages Wimax Uses

Three ways to access the Internet today…. Dial-up access : pay for a local call every time we dial the Internet. In addition phone line is engaged while we are on the Internet. Broadband access : In your home, you have either a DSL or cable modem. At the office, your company may be using a T1 or a T3 line. Wi-Fi access : In your home, you may have set up a Wi-Fi router that lets you search the Web while you are connecting with your laptop. On the road, you can find Wi-Fi hot spots in restaurants, hotels, coffee shops and libraries.

Why we use wimax The main problems with broadband access are that it is more expensive and it doesn't reach all areas. The main problem with Wi-Fi access is that hot spots (access point of wireless network) are very small, so coverage is small. Due to these problems we are using advance technology called WIMAX

What is Wimax WiMAX stands for Worldwide Interoperability of Microwave Access, is a wireless Internet service designed to cover wide geographical areas serving large number of users at low cost. WiMax is a foundation set on the IEEE 802.16 standards. However the name given to WiMax was suggested by WiMax Forum in 2001.WiMax technology is also termed as wireless broadband this is because it is believed that it can replace DSL cable network. Wimax defining wide area wireless data networking  

Typical Network Ranges WAN IEEE 802.16e IMT-2000(3G) (Nationwide) Wide Area Network MAN IEEE 802.16-2004 WiMAX (50 Km) Metropolitan Area Network LAN IEEE 802.11 (150 m) Local Area Network PAN IEEE 802.15 Bluetooth (10m) Personal Area Network

A WiMAX system consists of two parts TRANSMITTER A single WiMAX tower can provide coverage to a very large area – as big as 3,000 sq. miles. RECEIVER The receiver and antenna could be a small box or PCMCIA card or they could built into a laptop as the way Wi-Fi access is today.

HOW DOES IT WORK ? WiMAX uses microwave radio technology to connect computers to the internet in place of wired connections such as DSL or cable modems. It works very much like cell phone technology in that reasonable proximity to a base station is required to establish a data link to the Internet. Users within 3 to 5 miles of the base station will be able to establish a link using NLOS technology with data rates as high as 75 Mbps. Users up to 30 miles away from the base station with an antenna mounted for LOS to the base station will be able to connect at data rates approaching 280 Mbps.

Wimax Network Architecture

WiMAX network architecture comprises three major elements or areas Remote or Mobile stations:  These are the user equipments that may be mobile or fixed and may be located in the premises of the user. Access Service Network (ASN ):   This is the area of the WiMAX network that forms the radio access network at the edge and it comprises one or more base stations and one or more ASN gateways. Connectivity Service Network (CSN):   This part of the WiMAX network provides the IP connectivity and all the IP core network functions. It is what may be termed the core network in cellular parlance.

The overall WiMAX network comprises a number of different entities that make up the different major areas described above. These include the following entities. Subscriber Station (SS) / Mobile Station(MS) : The Subscriber station, SS may often be referred to as the Customer Premises Equipment, CPE. Base Station (BS) : The base-station forms an essential element of the WiMAX network. It is responsible for providing the air interface to the subscriber and mobile stations. Authentication, Authorization and Accounting Server, AAA: As with any communications or wireless system requiring subscription services, an Authentication, Authorization and Accounting server is used. This is included within the CSN.

ASN Gateway (ASN-GW):   The ASN gateway within the WiMAX network architecture typically acts as a layer 2 traffic aggregation point within the overall ASN. The ASN-GW may also provide additional functions that include: intra-ASN location management and paging, radio resource management and admission control, caching of subscriber profiles and encryption keys. Home Agent, HA:   The Home Agent within the WiMAX network is located within the CSN. With Mobile-IP forming a key element within WiMAX technology, the Home Agent works in conjunction with a "Foreign Agent", such as the ASN Gateway, to provide an efficient end-to-end Mobile IP solution. The Home Agent serves as an anchor point for subscribers, providing secure roaming with QOS capabilities.  

Interfaces of wimax R1—Represents the interface between the wireless device and the base station. R2—Represents the link between the MS (mobile station) and the CSN (connectivity service network). R3—Represents the link between the ASN (access service network) and the CSN. R4—Represents the link between an ASN and another ASN. R5—Represents the link between a CSN and another CSN. R6—Located within an ASN and represents a link between the BS (base station) and the ASN-GW. R7—Located within the ASN-GW and represents internal communication within the gateway. R8—Located within an ASN and represents a link between two base stations.

Forms of Wireless Service NLOS (Non Line of Sight) There is the non-line-of-sight, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to Wi-Fi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles. LOS ( Line of Sight) There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.

Relationship with other Wireless Technologies Mobile Wi-Fi WiMAX Max. Speed 2 Mbps 16 Mbps 54 Mbps 100 Mbps Coverage Several Miles 300 feet 50 miles Airwave Licensed Unlicensed Either Advantages Range, Mobility Speed, Mobility Speed, Price Speed, Range Disadvantages Slow, Expensive High Price Short Range Interference issues

WIMAX SPECTRUM WiMax Forum is focusing on 3 spectrum bands for global deployment: Unlicensed 5 GHz: Includes bands between 5.25 and 5.85 GHz. In the upper 5 GHz band (5.725 – 5.850 GHz) many countries allow higher power output (4 Watts) that makes it attractive for WiMax applications. Licensed 3.5 GHz: Bands between 3.4 and 3.6 GHz have been allocated for BWA in majority of countries. Licensed 2.5 GHz: The bands between 2.5 and 2.6 GHz have been allocated in the US, Mexico, Brazil and in some SEA countries. In US this spectrum is licensed for MDS and ITFS.

WiMax Standards 802.16 802.16a 802.16-2004 802.16e-2005 Date Completed December 2001 January 2003 June 2004 December 2005 Spectrum 10-66 GHz < 11 GHz < 6 GHz Operation LOS Non-LOS Non-LOS and Mobile Bit Rate 32-134 Mbps Up to 75 Mbps Up to 15 Mbps Cell Radius 1-3 miles 3-5 miles

What are the Advantages What are the disadvantages A Single WiMAX main Station can serve hundreds of users. Endpoints install within days instead of the weeks required for wired connections. Data rates as high as 280 Mbps and distances of 30 miles are possible. Users can operate mobile within 3-5 miles of a base station at data rates up to 75 Mbps. No FCC radio licensing is required. Less expensive than DSL or coaxial cable. What are the disadvantages Line-of-Sight is required for long distance (5-30 mile) connections. Heavy rains can disrupt the service. Other wireless electronics in the vicinity can interfere with the WiMAX connection and cause a reduction in data throughput or even a total disconnect.

Uses of Wimax Connecting Wi-Fi hotspots with each other and to other parts of the internet. Providing a wireless alternative to cable and DSL for last km broadband access. Providing a high-speed mobile data and telecommunications services (4G). Providing a diverse source of Internet connectivity as a part of business continuity plan. Providing Nomadic (mobile) connectivity.

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