Why Wireless?

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.

Bringing Smiles to the Business Subscriber’s Face

Internet
Service Providers (ISPs) know that the best customers are also the most
demanding. Providing high-speed access for demanding business subscribers in
suburban and rural areas is a challenging opportunity due to the lack of
infrastructure. High-speed leased lines are expensive and hard to obtain,
especially for small, independent local telephone companies. A better solution
is needed — one that provides reliable quality of service over longer
distances - for more users and avoids giving away access dollars to the telco.

In this scenario, the ISP decides to deploy a wireless network that delivers
E1 service to small businesses for voice and Internet access; larger businesses
receive E2/E3 service with wayside E1 for data, video, Internet/IP and PBX
traffic; and highly cost-conscious subscribers receive 10BaseT IP service.
Initially, the wireless network uses a variety of point-to-point dedicated links
and point-to-multipoint shared access links, using unlicensed frequencies (see
Figure: Business Subscriber Access). Customers are connected to the Internet
within weeks, at much faster speeds than before, so that many more users at each
location are now online simultaneously. Eventually, the network proves so
reliable and profitable that customer commitments allow the ISP to upgrade most
of the wireless network to licensed frequencies, with dedicated point-to-point
wireless connections, as well as initiating CLEC status for enhanced services to
compete with the local phone company. Subsequently, the ISP expands coverage
into an adjacent metropolitan area, using a 100 Mbps wireless bridge to
establish a link to a remote PoP and provide high-speed backhaul of Internet
traffic.

What the Suburbs-located Businesses Waited For

Many enterprises are frustrated by the bandwidth bottleneck because they have
branch offices, factories or warehouses located outside the urban core where
high speed access is relatively cheap and plentiful. For example, the downtown
headquarters may well be the only enterprise location in the metro area with
high-speed data connections. Operating LAN facilities at multiple remote
locations presents a significant internetworking challenge. Employees at a
suburban warehouse or a factory across town are isolated not only from high
speed Internet access but also from the large database on corporate LAN servers.

Wireless IP links ideally extend the individual enterprise LANs into a metro
enterprise WAN, with minimum additional equipment and cost (see Figure:
Enterprise WAN). Free e-mail transport and low-cost Voice over IP telephone
access or PBX extensions can be made available to all locations on the
enterprise WAN. This application can be even more compelling in developing
markets like India where satellite offices typically wait years for even basic
telephone service. Most enterprises will turn to a local carrier to provide the
actual wireless links, fueling new business opportunities.

Ideal for Educational Institutes and Campuses

Consider that a state-wide initiative to provide Internet access to all
public schools is issued, but the directive is limited by the high cost and
unavailability of high-speed lines. Slow dial-up lines prevent students from
completing assignments during class. An alternative? Consolidate all the school’s
computers on to a common LAN, either wired or wireless. One router or switch at
each school, can now provide a high-speed external 10BaseT port for Internet
access. High-throughput point-to-point wireless bridges connect the 10 Mbps
ports at each school within a school district to a central district hub.
Finally, the district hubs can be linked to the ISP or Network Service Providers
(NSPs) with a higher throughput device, for example, 1,100 Mbps wireless bridge,
giving a superior solution.

Similarly, an enterprise organized as a campus may have developed with
separate LANs and PBXs in each main building. There are significant advantages
to integrating the LANs into a single WAN and directly connecting the PBXs.
Users want to operate all network systems in a transparent manner, creating a
common platform, with shared applications and improved manageability. Similarly,
voice users want to call telephones in an adjacent building without dialing out
through the PSTN for ease-of-use and reduced cost. A wireless link with a
100BaseT bridge port and wayside E1 channel can meet these goals and be
installed in days. The 100 BaseT port connects to a WAN port on the LAN switch
or router at each building and each E1 port connects directly to each PBX local
trunk port.

This article is excerpted from a pocketbook by Western Multiplex