WHAT IS WiMAX?

WiFi

   Most of us are familiar with WiFi, which stands for Wireless Fidelity.  This is the wireless standard used in the home or office to transmit broadband internet signals from a DSL router or cable modem to computers and peripherals, or the device used to create an internet hot spot at a local Starbucks.  Although a very effective technology, it has its drawbacks: it is normally limited in distance (up to 300 ft), does poorly with interference, and is primarily used for indoor service.  WiFi has restricted ability to penetrate buildings or obstructions, and the information-carrying bandwidth is limited.  Furthermore WiFi has been plagued with security and quality of service (QoS) issues.

   WiFi wireless LANS are based on the IEEE 802.11 standards and have been a very successful first step in wireless deployment of broadband.

WiMAX

   WiMAX has been dubbed “Wi-Fi on steroids” and is governed by IEEE 802.16.  WiMAX stands for Worldwide Interoperability for Microwave Access.  The current code is 802.16-2004, which governs fixed wireless systems.  Ratification is pending for 802.16e, which provides for mobility for WiMAX.  Imax's only similarity to WiFi is in that it transmits over the airwaves (Wireless).  However there are many distinct differences:

    Current advocates of WiMAX tout its many advantages:

•  WiMAX can effectively be used for point-to-point backhaul over long distances (up to 30 Miles).

• Unobstructed, WiMAX can span many miles and cover wide areas (up to 30 Miles).  4-6 Miles in non line-of-site applications vs. 150-300 ft for WiFi.  This makes it suitable for entire cities and allows development of Metropolitan Area Networks (MANs) versus Local Area Networks for WiFi.

• WiMAX promises to be internationally standardized, facilitating large production runs by multiple suppliers, bringing down equipment pricing.  The WiMAX Forum will begin testing products to meet these standards by the end of 2005.

• WiMAX has a higher speed than WiFi and, depending on bandwidth availability, may produce data transmissions of up to 70 Mbps vs. 54 for WiFi.

• WiMAX can be used in both Line-of-Sight (LOS), for back-haul applications (up to 30 miles under ideal conditions), and non-LOS network access applications. 

• WiMAX can be used to connect multiple network hot spots, and provide last-mile connectivity directly to the home or business.

• WiMAX can use licensed or unlicensed spectrum.

• WiMAX is symmetrical in most cases providing the same throughput upstream and downstream

• Since WiMAX does not use the Medium Voltage power lines for transport, the Radio Frequency Interference caused by signal transport over the Medium Voltage system in a BPL application is not an issue.

   WiMAX makes a very strong partner for WI-FI and can be is used as a complementary technology in the case of joining multiple existing hot spots by providing economical backhaul to areas where WiFi is already in place.

POTENTIAL USES OF WiMAX

   WiMAX can be employed in a variety of architectures and in combination with other transport technologies.  For example:

1.                  An internet service company could put a tower within a few miles of your home.  Its service may be purchased and you can decide on either a modem, upgraded computer with built-in WiMAX circuitry or a PCMCIA card for your existing computer.  Intel has promised to install WiMAX architecture in all of its computer chips starting in 2005 and provide mobility by 2007.  This integration of WiMAX capabilities into products should further deflate the cost of WiMAX related services.  Speed will be faster than cable, costs will be much less because the provider will neither have to install - nor maintain - expensive cable plant (see Fig 1). 

Fig. 1

2.                  WiMAX is an intriguing option for providing VoIP.  This is very attractive to long distance carriers, looking to compete with the Regional Bell Operating Companies (RBOCs), and would allow them to compete for local phone service without having to pay fees to the RBOCs for using their local lines.  In 2004 AT&T paid over $8 B in access fees.  Proponents claim WiMAX could provide streaming video, wireless, high speed gaming, and personal video conferencing services.    Nokia has announced they will offer a WiMAX handset in 2007.  This could enable competition in cell phone markets. 

3.                  WiMAX uses line-of-site to transmit an internet signal to a second tower or as backhaul.  It also is said to use non line-of-site mode for the last mile, to reach urban and rural residences and businesses.

4.                  Another variation on the last mile architecture is the use of the WiMAX transmitter for backhaul and transmission to a receiver at the pole. A bypass connector then attaches to the Low Voltage Line and the signal is then transmitted via the electrical wiring or LAN inside the home (see Fig. 2).

Fig. 2

5.         WiMAX technology is used to transmit to several WiFi ‘Hot Spots.’ Recently, during the Tour de France, journalists were provided with WiMAX technology from Intel and France Telecom/Orange.  The system served WiFi Hot Spots with WiMAX being used for backhaul.  The installation at each stage took less than an hour, giving reporters better-than-DSL speeds to submit t information (see Fig. 3)

Fig. 3

6.         WiMAX is an access solution for urban locations with high-density populations. According to WiMAX advocates, an installation with data deliveries of 70 Mbps can simultaneously support 60 businesses and over 1000 homes.

7.         WiMAX is also envisioned as a potential solution for rural America, where its longer transmission spans and ability to share towers, appears to provide a more cost-effective solution than other methods- including BPL.

8.         WiMAX is also touted as a technology capable of improving the reliability of the electrical power distribution grid: providing vital fast-response feedback for utility’s SCADA control Systems, Automated Meter Reading systems, substation monitoring- as well as streaming video and (visual) security systems.