Transmission speeds for WAN connections have been limited primarily by telephone company (telco) services. The Public Switched Telephone Network (PSTN) is the most widely available access network through copper wires installed by the Incumbent Local Exchange Carrier (ILEC). However, dial-up modem performance is unsatisfactory for almost every LAN business application. Clearly, the PSTN was never designed to handle continuous, full-duplex, high-speed data traffic, let alone high-end graphics and full-motion video! Telcos in India also provide ISDN and leased line connections like 64 Kbps, nx64 Kbps, E1s and fractional E1s. However the choice is limited in terms of products as well as service providers. If at all these services are getting affordable—they are still not that easily available.

As for faster connectivity than this, a number of service providers, including ISPs, bandwidth providers, ILECs and CLECs are busy building their networks to provide services such as DSL, cable Internet connectivity and fibre optic connectivity. Though some of these are available in pockets, they can hardly be depended upon to build a comprehensive Internet access infrastructure or a corporate wide area network.

In contrast, wireless technology can be installed, as required, with no right-of-way limitations. So, time to market is extremely fast and there is no waiting for the telco to provide service. Access to rooftops is generally needed at each location to facilitate line-of-sight requirements, with distances typically up to 50 miles. Excellent full duplex throughput ranging from 64 Kbps to 100 Mbps (and beyond) for voice, data and video services is available. Wireless is particularly cost-effective: once the capital investment is paid, there are no monthly expenses accrued.

Extending Presence—Fast and Simple

To be truly competitive and to get to the market in the fastest possible time, ISPs and Competitive Local Exchange Carriers (CLECs) will be installing wireless elements in their networks. Two typical applications emerge as service providers roll out their networks to serve new customers.

In the first example, a service provider has built a high-speed fiber ring in the urban core of a metropolitan area network. In order to reach additional high capacity business customers, both downtown and just outside the urban core, the carrier has one alternative of relatively costly underground construction to extend short spurs off the fiber ring, eventually building additional fiber rings. With a $50 million budget, the project will take three years to complete. This carrier knows that his competitors won’t wait three years, nor will his customers, so he needs a much faster solution. A preferred alternative (see Figure: Fiber Network Enhancement) is a wireless IP network, deployed as several E1, E2, E3, 10BaseT or 100BaseT point-to-point wireless spurs off the key existing fiber nodes, directly to the rooftops of the customers, supplying 80 percent of the additional carrier revenues. The license-free UNII equipment can be installed in months and will be redeployed to future customers as the wireless links are converted to fiber. All of the facilities remain under the ISPs/CLECs operational control. Each additional customer receives dedicated high-speed access to the carrier network and profitability is achieved in less than six months.

The second example spotlights a carrier who wants to extend a service area by establishing a remote Point of Presence (PoP) in another city over 10 miles away. The remote PoP connection could be made using a telco leased line, however, that would take the phone company 3-6 months to install and the ISP/CLEC would have to pay significant leased line fees every month. Also, if the leased line went down, all of the service provider’s customers in the other city would be out-of-service until the phone company resolved the problem. Instead, the ISP/CLEC obtains access rights for a small flat panel antenna on the rooftop of a tall building in the remote city. Then, a wireless IP link establishes a Fast Ethernet connection to the remote POP, where a Layer 3 switch connects the service provider’s VPN services to local customers. All of the telco access dollars are retained by the ISP/CLEC for investment in growing the business.