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Wimax Technology Overview

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Autor:  anton  12 October 2010
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WiMAX: An Information Study

WiMAX: An Information Study

This study will define what WiMAX is; provide a brief history of the technology; describe how WiMAX works and discuss its uses and potential benefits. WiMAX has the potential to become an extension to the reach of broadband solutions. WiMAX is still emerging and growing but shows signs of picking up a wider acceptance in the broadband marketplace. Could WiMAX be the broadband of the future?

What is WiMAX?

WiMAX, short for Worldwide Interoperability for Microwave Access or the Air Interface Standard and designated as 802.16 by the Institute of Electrical and Electronics Engineers (IEEE), is considered to be a broadband wireless technology (BWA) used to create metropolitan area networks (MAN). The standard covers both the Media Access Control (MAC) and the physical (PHY) layers

According to WiMAX Forum, the consortium behind WiMAX, “WiMAX is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL. WiMAX will provide fixed, nomadic, portable, and eventually, mobile wireless broadband connectivity without the need for direct line-of-sight with a base station.”

A number of PHY considerations were taken into account in the development of WiMAX. At higher frequencies, line of sight eases the effect of multipath, allowing for wide channels, typically greater than 10 MHz in bandwidth. This provides very high capacity links on both the uplink and the downlink. For sub 11 GHz non line of sight capability is a requirement. The original IEEE 802.16 MAC was enhanced to accommodate different PHYs and services, which address the needs of different environments. The standard is designed to accommodate either Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD) deployments, allowing for both full and half-duplex terminals in the FDD case.

The MAC was designed specifically for point-to-multipoint (PMP) wireless access environment. It supports higher layer or transport protocols such as ATM, Ethernet or Internet Protocol (IP), and is designed to easily accommodate future protocols that have not yet been developed. The MAC is designed for very high bit rates (up to 268 mbps each way) of the truly broadband physical layer, while delivering ATM compatible Quality of Service (QoS); UGS, rtPS, nrtPS, and Best Effort.

The frame structure allows terminals to be dynamically assigned uplink and downlink burst profiles according to their link conditions. This allows a trade-off between capacity and robustness in real-time, and provides roughly a two times increase in capacity on average when compared to non-adaptive systems, while maintaining appropriate link availability.

The 802.16 MAC uses a variable length Protocol Data Unit (PDU) along with a number of other concepts that greatly increase the efficiency of the standard. Multiple MAC PDUs may be concatenated into a single burst to save PHY overhead. Additionally, multiple Service Data Units (SDU) for the same service may be concatenated into a single MAC PDU, saving on MAC header overhead. Fragmentation allows very large SDUs to be sent across frame boundaries to guarantee the QoS of competing services. And, payload header suppression can be used to reduce the overhead caused by the redundant portions of SDU headers.

The MAC uses a self-correcting bandwidth request/grant scheme that eliminates the overhead and delay of acknowledgements, while simultaneously allowing better QoS handling than traditional acknowledged schemes. Terminals have a variety of options available to them for requesting bandwidth depending upon the QoS and traffic parameters of their services. They can be polled individually or in groups. They can steal bandwidth already allocated to make requests for more. They can signal the need to be polled, and they can piggyback requests for bandwidth.

According to WiMAX Forum, the consortium behind WiMAX, “WiMAX is a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL. WiMAX will provide fixed, nomadic, portable, and eventually, mobile wireless broadband connectivity without the need for direct line-of-sight with a base station.”

The versatility of both the PHY and Mac allow WiMAX networks, a range of 50 km, without line of site, provide data rates up 70 Mb/s. They are able to connect and extend WiFi (802.11) hotspots and provide wireless Internet access over a large area.

Figure 1:

History of the technology.

The IEEE approved the initial 802.16 standard for wireless MAN for the 10-66 GHz frequency range in December 2001. The 802.16a extension for sub-11 GHz was approved in January 2003. Amendment 802.16c, approved in December of 2002, “updates and expands Clause 12 of IEEE Std 802.16-2001, which concerns system profiles that list sets of features and functions to be used in typical implementation cases. Errors and inconsistencies in IEEE Std 802.16-2001 are also corrected. The scope is limited to 10–66 GH.” The 802.16-2004 standard was ratified by the IEEE in June 2004 and includes 802.16a and 802.11c. The 802.16e standard, which adds mobility, is being reviewed by IEEE and expects approval in mid-2005.

The growth of WiMAX?

WiMAX is being implemented all over the globe with a US company leading the way. Clearwire a company headquartered out of Kirkland has been buying spectrum in the US and in Europe with 34 million dollars of spectrum purchased in the last 2 months. They are delivering wireless solutions for backhauls and for wireless home services that compare to DSL and Cable.

Figure 2: Clearwire’s recent coverage in the United States.

AT&T in Atlanta, right now, is testing WiMAX. They are looking to the broadband solution to bypass local carriers and bring the last mile to the customers themselves. This could be a huge savings to AT&T with local carriers costing them around 10 billion. The last mile, which is the most expensive for ISP’s and carriers, can be done rather inexpensively with WiMAX technology. This is achieved from not needing to run cable or wire and tear up streets to get to the customers doorstep.

With 70 mbps throughput WiMAX will be a good solution for getting companies up and running fast on the Internet. WiMAX technology will improve wireless distances, rates, and bandwidth to areas not accessible to DSL or Cable subscribers. With WiMAX technology you can take your connection anywhere within the service area and if the world standardizes WiMAX you may be able to get connected anywhere in the world with global roaming access.

Although this all sounds positive for WiMAX, the truth is the equipment just isn’t available yet and carriers and ISPs won’t buy into a technology that just isn’t available. For this reason WiMAX started out slow for the inaugural year, with 16.4 million dollars in equipment sales. This was also due to the 802.16e standard not being in place, but now that the standard is all but legally agreed upon, equipment sales are expected to jump to 124.5 million in 2005. Another hold back besides standardization and new equipment is the regulators of spectrum worldwide. The FCC and other International government regulators are looking at how to best license the 2.5GHz and 5.4 GHz spectrums.

How will WiMAX progress in the future?

While WiMAX is in the works of being implemented all over the globe there are not many organizations utilizing it as of yet. According to “Wi Not?” in the Wired News, Intel is currently working with over 100 cities all over the world to implement government usage of its WiMAX product. Cities as far as Taipei and Jerusalem, and as near as Philadelphia, PA, Cleveland, OH, and Corpus Christi, TX are looking into testing the use of WiMAX for their public services such as the police force, emergency response teams, building inspectors, etc. Enhancing the ability to communicate more efficiently across distances in these areas would greatly assist these groups in providing better services.

In February of this year, WiMAX, T-Mobile, Southern Trains, and Nomad Systems teamed together in the United Kingdom to implement a two-way connection of up to 32Mbps to laptop and PDA users riding along the rail systems. Other providers already operate a WiFi connection among the rail systems in the United Kingdom, but T-Mobile claims it’s will be the first ‘genuine broadband’ connection available in this area due to its use of WiMAX. Nigel Wallbridge, executive chairman of Nomad Digital, states in an article in ZDNet UK:

“Although the London to Brighton line presents many challenges we have proved that high-speed wireless access to moving trains is possible without building huge towers or other costly infrastructure. Whether the train travels through tunnels, bridges or through high hedgerows, customers should not experience a drop in service.”

It appears that this technology will only continue to grow and develop. There are several discussions about cell phone providers utilizing WiMAX for connections that are more efficient as well. AT&T, as well as T-Mobile, seems to be progressing in this area based on their involvement with other organizations like the above mentioned example in the United Kingdom. Other than providing the technology for consumer usage, there doesn’t appear to be any organizations utilizing WiMax as of yet for business purposes.

Regulatory Information.

The globe aspect of WiMAX is changing as we speak at the time of this paper.. In the United States the regulatory system seem to be up and running.

From the research that has been done, the regulatory rules are trying to keep up with technology and spread of new technology.

From the excerpts from the web page:

The regulator is considering a light licensing scheme that will support simplified and fast assignment of licenses, but s likely to retain a regional rather than a national scheme.

The agency is following a technology neutral approach. The aim is for the 3.5GHZ spectrum to be deployed for diverse technologies, WiMAX being just one. The frequencies are to be primarily for fixed wireless internet access, but the regulator will remain flexible on using excess capacity for other purposes.

The Technology that is including WiMAX is fast growing and the regulatory rules need to be modified. The bandwidths and how they are allotted to the business world. In Germany and France, the regulatory commissions are giving the agency a site licensing so they can stimulate spectrums for WiMAX.

The United States it is not necessary to stimulate spectrums because of the technology that already exists. In Europe and third world countries, they have to be lite on their requirement to let the technology take hold in the country.

The French regulator Arcep has been drawing up procedures for a new round of 3.5GHZ allocations, planning to offer two licenses in each of 22 regions and possibly some additional ones in densely populated cities. Currently, Altitude holds the only national license and is deploying it s first pre-WiMAX networks.

The regulatory aspect of WiMAX seems to have no effect on the United States. In the other countries, they have to change the regulatory licensing to stimulate spectrum to install WiMAX.

What can WiMAX do for you?

WiMAX has many possibilities for the average user, businesses and on a global scale. With the advent of this new technology, it is possible to make connections to resources they were not possible in the past. The wide range and scope of WiMAX opens up many personal and business opportunities for companies and small business alike.

Individuals

As a mobile worker, the impact of WiMAX can be felt immediately. However, imagine roaming around an unknown town in a rental car and getting lost in that town. You are almost out of gas, hungry, looking for your hotel, and need to check e-mail and voicemail from the home office. This might normally be a problem. WiMAX is in the area.

The local WiMAX has the capability for a person to be able to connect and solve all of the possible issues at once. Connecting to the local WiMAX, e-mail and voicemail can be checked, searching the Internet for directions can be accomplished, and finding a restaurant is no problem. This helps the average worker doing business on the road.

This is good for the average home user as well. There are many people outside of many major cities that do not have the ability to pick up broadband access. They either are restricted by physical location or distance from a provider. There is also the problem of the specific carrier not wanting to spend the money to extend their broadband reach to a small community or a small group of people. (WiMAX Industry, 2005)

With WiMAX, it is possible to extend the broadband range without having to extend a wired infrastructure. With the local provider putting up WiMAX towers in the area they can extend the reach of their service by fifty km. This can help facilitate the home user’s need to have broadband available.

The impact to the average individual can be seen with just a couple of examples. The success of the home user definitely extends the reach of many businesses.

Businesses

The impact on business can be felt immediately. There are many possibilities for a business to take advantage of. Businesses have taken advantage of many new technologies to expand the offerings.

One of the biggest possibilities of the WiMAX technology is disaster recovery and redundancy. Most businesses are wired directly into the Internet. They have some sort of landline connection. These types of connection may vary but they are all susceptible to the same sort of problems. If a local line is cut, there is not much a business can do to get their connection functional again. They are reliant upon the service provider to fix the broken connection again. (Wexler, 2005)

Another example may be provider equipment failure. There are many times where a blade or port goes bad on equipment. Equipment seems to fail at the worst times possible. If that equipment fails, the business will lose its connection. Productivity and money will be lost.

If WiMAX were in place, it would be possible to have that connection fail over to the wireless network. If they’re in good range of the station and have a good connection, the business users may not even notice the failover. It is an excellent solution for a business to choose to maintain a persistent connection.

Another possibility that businesses could use to their advantage is sales. For example, if a person walks into a store expecting to find a specific product, and that product is not there, what can the person do? Most people would turn around and go home.

With WiMAX, a person can check the inventory of other nearby stores with their PDA before they even leave the first store. If the product is in another nearby store, they can go to that store to make the purchase. On the other hand, while they are in the store they can do a price check to make sure they are getting the best deal from that store. There is a good possibility that this type of technology really pushes retailers to compete.

Globally

After reviewing some of the examples above, it is evident how this may affect the global market. Many companies can possibly benefit from the adoptions of WiMAX.

The companies producing the equipment needed for this technology will be in great demand and need in the near future. From a global economic standpoint, this has incredible potential for investors. No matter where you are in the world, you can get a head start on the opportunities. (silicon.com, 2005)

Other countries will have the opportunity to adopt the new technology as well. They can take advantage of this technology by keeping the cost of building infrastructure down. Many of the connections to the Internet are helped along by local governments. If they use WiMAX, they will only have to buy the technology required by WiMAX. They can put up a tower and provide service to a small community. They do not have to incur the expense associated with hard wiring every house in that community.

This can help poor communities as well. If there are services that a community needs, the government could provide that service at low cost. Say for example something like VoIP. If they need to get the community connected quickly, the government could put that infrastructure in vary quickly. That community could go mobile and have communication in a very short time.

Imagine a community struck by disaster. Normally landlines are severed or become inoperable due to the disaster condition. If there were a WiMAX infrastructure in place, it could be possible to provide that area with the ability to communicate. They could get the help they need.

References

IEEE. (2005). The IEEE 802.16 Working Group on Broadband Wireless Access Standards. from http://grouper.ieee.org/groups/802/16/pub/backgrounder.html

Brain, E. G. a. M. (2005). How WiMAX Works. Retrieved 23 Aug, 2005, from http://computer.howstuffworks.com/wimax.htm/printable

WiMAX Forum. (2005). Retrieved 23 Aug, 2005, from http://www.wimaxforum.org/about

WiMAX Forum. (2005). Retrieved 23 Aug, 2005, from http://www.wimaxforum.org/technology

802.16 -IEEE Standard for Local and metropolitan area networks

Part 16: Air Interface for Fixed Broadband Wireless Access Systems

IEEE Std 802.16, 2001

Published by

The Institute of Electrical and Electronics Engineers, Inc.

802.16c -IEEE Standard for Local and metropolitan area networks

Part 16: Air Interface for Fixed Broadband Wireless Access Systems

Amendment 1: Detailed System Profiles for

10–66 GHz

IEEE Std 802.16c, 2002

Published by

The Institute of Electrical and Electronics Engineers, Inc.

Friedman, M. (2005). WiMax market to hit $124.5 million this year. Retrieved 23 Aug, 2005, from http://www.commsdesign.com/news/showArticle.jhtml?articleID=166403703

News, W. N. (2005). WiMAX Network News. Retrieved 23 Aug, 2005, from http://wimaxnetnews.com/

Reality TV Gets Virtual. (2005). Retrieved 23 Aug, 2005, from http://www.wired.com/news/business/0,1367,68588,00.html?tw=wn_tophead_6

Wearden, G. (2005). T-Mobile uses WiMax for train Wi-Fi. Retrieved 23 Aug, 2005, from http://news.zdnet.co.uk/communications/wireless/0,39020348,39188192,00.htm

WiMAX Trends. (2005). Retrieved 23 Aug, 2005, from http://www.wimaxtrends.com/feature.html

Silicon.com. (2005). WiMAX: The Business Case for Fixed Wireless Access in Emerging Markets. Retrieved 23 Aug, 2005, from http://whitepapers.silicon.com/0,39024759,60144095p,00.htm

Joanie Wexler. (2005). Why WiMax. Retrieved 23 Aug, 2005, from http://www.computerworld.com/mobiletopics/mobile/technology/story/0,10801,99680,00.html?SKC=mobile-99680

WiMAX Industry. (2005). WiMax may pose fresh challenge to broadband. Retrieved 23 Aug, 2005, from http://www.wimax-industry.com/ar/1k.htm



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