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The majority of countries around the world have embraced the 5 GHz spectrum for licence-exempt communications. The 5.15 and 5.85 GHz bands have been designated as licence exempt in much of the world. Approximately 300 MHz of spectrum is available in many markets globally, and an additional 255 MHz of licence-exempt 5 GHz spectrum is available in highly populated markets like the USA.
Some governments and service providers are concerned that interference resulting from the availability of too many licence-exempt bands could affect critical public and government communication networks, such as radar systems. These countries and entities have become active in establishing limited control requirements for 5 GHz spectrums. For example, the UK is currently introducing restrictions on certain 5 GHz channels and considering enforcement of the use of the DFS function.
One key point which needs emphasis is that unlicensed does not mean unregulated, and all operators providing wireless services still need to maintain a no-interference working plan and a ‘good neighbour’ attitude along with efficient spectrum utilization.
Benefits of Licence-exempt WiMAX Systems
The costs associated with acquiring licensed bands are leading many WISPs and vertical markets to consider licence-exempt solutions for specialized markets, such as rural areas and emerging markets.
Licence-exempt solutions provide several key advantages over licensed solutions, including lower initial costs, faster roll-out and a common band that can be used in much of the world. These benefits are fuelling interest and have the potential to accelerate broadband adoption. Service providers in emerging markets, such as developing countries or mature countries with underdeveloped areas, can reduce time to market and initial costs by quickly deploying a licence-exempt solution without timely permits or auctions. Even mature areas can benefit from licence-exempt solutions.
Some service providers can use a licence-exempt solution to provide last-mile access for home, business or backhaul or as a supplemental network backup for their licensed or wired networks. A licence-exempt
solution is regulated in terms of the transmission output power, although a permit is usually not required. A device or service can use the band at any time as long as output power is controlled adequately.
Providers who are particularly concerned about QoS, for example, may find that a licensed solution provides them with more control over the service. A service provider wanting to serve an emerging or underdeveloped market with a business class service can use a licence-exempt solution, with proper network design including site surveys and specialized antenna solutions, to offer certain Service Level Agreements (SLAs) for their specialized markets.
The 802.16 standard will help the industry provide solutions across multiple broadband segments. WiMAX was developed to become a last-mile access technology comparable to DSL, cable and T1 technologies. It is a rapidly growing technology that is most viable for backhauling the rapidly increasing volumes of traffic being generated by Wi-Fi hotspots.
WiMAX is a MAN technology that fits between wireless LANs, such as 802.11, and wireless wide-area networks (WANs), such as the cellular networks. Bandwidth generally diminishes as range increases across these classes of networks. Proponents believe that WiMAX can serve in applications such as cellular backhaul systems, in which microwave technologies dominate, backhaul systems for Wi-Fi hot spots and most prominently as residential and business broadband services.
WiMAX is billed to support many types of wireless broadband connections including but not limited to the following: high-bandwidth MANs, cellular backhaul, clustered Wi-Fi hotspot backhaul, last-mile broadband, cell phone replacements and other miscellaneous applications such as automatic teller machines (ATMs), vehicular data and voice, security applications and wireless VoIP. Today, wherever available, these applications use expensive, proprietary methods for broadband access (Figure 5.1).
WiMAX was developed to provide low-cost, high-quality, flexible, BWA using certified, compatible and interoperable equipments from multiple vendors. As WiMAX is based on interoperability-tested systems that were built using the IEEE 802.16 standard-based silicon solutions, WiMAX will reduce costs. WiMAX is well placed to address
The Business of WiMAX Deepak Pareek © 2006 John Wiley & Sons, Ltd
Figure 5.1 WiMAX applications
challenges associated with traditional wired access deployment types such as:
• large area coverage access, covering a large area (also referred to as hot zones) around the base station and providing access to 802.16 REV E clients using point-to-multipoint topology;
• last-mile access, connecting residential or business subscribers to the base station using point-to-multipoint topology;