Reaching Out Via Satellite Backhauling

The use of satellite links to backhaul cell phone and other handheld wireless device traffic enables service providers to reach more customers and gain new revenue streams. For developing countries in particular, this ability to quickly and seamlessly deploy cell phone infrastructure to previously unserved areas can be crucial for supporting and enhancing economic development.

Backhauling via satellite is becoming more attractive thanks to satellite equipment vendors that offer reliable, affordable and flexible solutions which can readily extend the reach of existing cellular phone and wireless broadband networks. At the same time, the idea of using satellite links to meet the growing demand for new third- and even fourth-generation Internet Protocol (IP)-based services — known as 3G and 4G services — including mobile broadband and TV is gaining acceptance in hybrid networking circles.

The focus primarily is on Global System for Mobile Communications (GSM) cell phone networks, which accounts for about 80 percent of worldwide cellular traffic, far ahead of code division multiple access (CDMA) at 14 percent and time division multiple access (TDMA) at 6 percent, according to “GSM Cellular Backhaul: Extending the Edge of a GSM Network,” a June white paper from iDirect Technologies Inc. “While GSM is one of the most pervasive technologies in the metropolitan mobile communications market today, it is also the standard of choice in developing markets. As the edge of existing networks continue to press outward, satellite becomes the de facto solution to extend to more remote regions.”

According to Claude Rousseau, senior analyst for NSR, lower satellite backhaul costs per GSM telephone call are being achieved via more efficient backhaul architectures using voice compression and silence suppression along with new interface optimization techniques linking the GSM network’s base station controller to any number of remote base transceiver stations. “Legacy single channel per carrier (SCPC) carriage growth is slowing, leaving room for new access technologies such as demand assigned multiple access to be used exclusively or overlaid on top of the base network transport architecture,” he says. “Technologies currently exist for satellites to support low density, low traffic network topologies with each [transceiver] handling less than 2 megabits per second.”

Satellite also can facilitate the migration from a high-bandwidth application-agnostic service provisioning such as Internet trunking to much lower-bandwidth, application-aware scenarios, says Rousseau. “Moving mobile networks from asynchronous transfer mode and time division multiplexing to IP is gaining ground, and all types of backhaul solutions providers are adapting their wares to this new paradigm,” he says. “IP and LAN-to-LAN mesh architectures for GSM backhaul, for example, can enable local switching at the [transceiver]. There is also some implementation of two-tier backhaul architectures that lower satellites’ entry points via extensions with wireless backhaul technologies like local multichannel distribution system or fixed WiMax.”

As operators seek more bandwidth at the cheapest price they can exert huge pressure on a backhaul solution that needs to address all the inefficiencies of cellular network communications. “It means finding solutions to greatly diminish high overhead in a communications’ protocol such as IP, which eats up megahertz of bandwidth,” says Rousseau. “Multipoint-to-multipoint systems in either IP or Ethernet format are also gaining ground. Nowadays, vendors are coming up with their own LAN-to-LAN systems, and more two-tier satellite-wireless backhaul architectures are designed to address varying daily and weekly traffic patterns and loads.”

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