Wednesday, April 11, 2007

LMDS Fills the Fiber Gap

While nationwide long distance fiber optic bandwidth is readily available, last mile connectivity to places of business is another matter. Can you believe that less than 20% of commercial buildings are set up for fiber optic telecom service?

Hard to believe, but true. The reason is cost. Trenching fiber is expensive and hard to justify. Especially when every location already has telephone service and data service over copper is readily available. Both business DSL and T1 lines use conventional copper pairs originally provisioned as analog telephone lines. T1 service is good for 1.5 Mbps bidirectionally, but what if you need higher bandwidths?

Large enterprise telephony, medical image transmission and video post production are just a few applications that demand bandwidths higher than 1.5 Mbps. An incremental solution that is also very cost effective is to bond T1 lines to create total bandwidths of 3, 4.5 6, 7.5, 9, 10.5, and even 12 Mbps.

In some locations it is also possible to bring in coaxial cable based T3 lines that run at 45 Mbps. Bandwidths of 45 Mbps are typically carried as DS3 service on higher capacity fiber optic cables. OC3 SONET over fiber is actually one of the lower bandwidth services at 155 Mbps. Are there any other options when you need this much capacity but blanch at the price tag of establishing fiber loops to the nearest carrier point of presence?

XO is one of the carriers addressing this need in major metropolitan areas. They've just announced a wireless Internet service for Seattle businesses that offers speeds of 10 to 155 Mbps. Similar service was announced last month for Phoenix. Eventually, the XO subsidiary Nextlink will be serving all of its wireless holdings in 75 major metropolitan areas.

If 155 Mbps sounds high for what you expect from wireless Internet service, it is. Bandwidths of a few Mbps are more common for WISPs and satellite Internet providers. Nextlink's service isn't based on cellular Internet, such as EVDO, or WiFi service on the 2.4 or 5 GHz channels. It uses a much higher band of frequencies licensed for LMDS or Local Multipoint Distribution Service.

As its name implies, LMDS is a point to multipoint fixed wireless technology. Transmissions frequencies are in the 26 to 29 GHz band and 31 to 31.3 GHz band. These high frequencies are an order of magnitude or more about the cellular, WiFi and WiMAX frequencies. Such high frequencies have radio waves with very short wavelengths that don't penetrate buildings well. In fact, things like tree leaves and even heavy rains can disrupt the signals. In general, the shorter the transmission path the more reliable the data link.

These factors limit transmission ranges to 11 or 12 miles from the wireless hub. User buildings must have an unobstructed view of the XO hub. That works within dense metropolitan areas and perhaps even out into the suburbs a bit. The goal is an alternative to last mile fiber optic links at a cost savings for customers.

Other even shorter range technologies include laser beams good for building to building links within corporate campuses. Light beam services are good for only a few thousand feet, but that can make a big difference when the buildings are separated by a freeway or river.

Whatever your bandwidth requirements are, including digital telephone, dedicated Internet, point to point private lines and long haul transmission, you'll find excellent pricing and multiple options from our suite of carriers at Just let us know what your needs are and our friendly consultants will be happy to recommend the most cost effective services that get the job done.

Click to check pricing and features or get support from a Telarus product specialist.

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