Globalstar delivers outstanding voice and data quality around the world
by leveraging their extensive network of low-earth orbit satellites and
regional gateways to deliver a superior customer experience. To
understand why technology gives Globalstar a distinct advantage over
other satellite providers, some background information is required on
satellites, gateways, call flows, Path Diversity™, and wireless technology.
Satellites
There are primarily two different types of satellites used to deliver voice
and data services to customers: LEO (Low-Earth Orbit) and GEO
(Geostationary Orbit). Globalstar has built their network using LEO
satellites because of their ability to deliver superb voice quality.
Globalstar's satellites orbit 1,414 km (878 miles) above the
earth's surface, and take less than two hours to complete a full
rotation. Their relative proximity enables voice and data signals to
travel quickly, resulting in crisp, clear, reliable communications.
Even customers using low powered mobile satellite devices, such as
handheld phones, can expect digital voice quality that is comparable to
cellular. Given their speed and the vast number of satellites in orbit,
coverage gaps are minimal and typically correct within minutes. The LEO
satellites communicate easily with Globalstar's devices using
omni-directional antennas since they only need a clear line-of-sight to
the sky to work, not specific calibration.
In comparison, GEO satellites orbit roughly 36,000 km (22,369
miles) above the earth's surface, and move with the earth, never
changing location. Perceptible voice delays or echoes can occur because
of the significant distances involved in transferring signals. GEO
satellite devices are relatively expensive, and use directional
antennas which must be pointed directly at a satellite to work.
Gateways
Gateway facilities enable voice and data transfers to take place
between Globalstar's wireless satellite network and the traditional
public-switched telephone network (PSTN). Globalstar uses many
strategically located gateways around the world to efficiently handle
these transfers, thus optimizing voice and data quality. Network system
upgrades can be made quickly and easily at these regional gateway
facilities, thus enabling Globalstar to rapidly deploy service
enhancements to customers.
Call Flows
Globalstar's call flow was designed to meet one objective - deliver
superb voice quality. To achieve that result, outbound calls from
Globalstar's phones are directly connected to a minimum of one and up
to three LEO satellites at one time, and then delivered to the closest
regional gateway for call completion through the PSTN. Incoming calls
follow the same course, but in reverse. By comparison, some LEO
satellite service providers transfer calls between satellites until
they are within range of their single gateway. This call flow can
result in a high degree of voice degradation depending on the number of
satellite hand-offs needed to reach this one gateway.
Path Diversity™ & Coverage
Globalstar uses a patented method of signal reception, called Path
Diversity™, to connect a single call with up to three satellites at one
time, to significantly reduce voice delay and enhance voice quality.
Path Diversity™ permits a digital receiver to combine multiple,
relevant signals of varying strengths into a single, static-free
signal. As satellites move in and out of view, they are seamlessly
added to and removed from a call in progress, thereby reducing the risk
of call interruption. This enables Globalstar to provide broad coverage
with less potential for signal blockage from buildings, terrain or
other natural features.
Multiple LEO satellites working in concert guarantee that if a
single satellite temporarily fails, another one can quickly respond and
overall coverage will not be significantly impacted. By comparison, a
single GEO satellite provides broad coverage, resulting in wide-spread
service disruptions if it goes off-line, even temporarily. Globalstar's
service covers latitudes from 70° north to 70° south, which is more
than 75% of the world's surface area. The network was designed to
service the temperate zones of the world where the majority of
Globalstar's customers need coverage; however, coverage also extends
across much of the earth's torrid zones, closer to the equator. A
dedicated staff regularly monitors Globalstar's network to ensure that
network operations are optimal at all times.
Wireless Technology
Globalstar utilises a version of Code Division Multiple Access
(CDMA) technology based upon the IS-95 CDMA standard. CDMA technology
forms the foundation for 3G (Third Generation) wireless services, which
are in use by over 128 million people around the world. This digital
transmission technology allows a large number of wireless customers to
simultaneously access a single radio frequency channel. The result is
less interference, and a many-fold increase in capacity when compared
to analogue systems such as Frequency Division Multiple Access (FDMA).
Globalstar's state-of-the-art technology is proven, and has been
designed to take customers well into the future of wireless
communications.
All of these elements combine to give Globalstar a distinct
advantage over other satellite providers. Customers require high
quality voice and data services, coverage and reliability. Globalstar
delivers on all points. For additional information contact an
authorised Globalstar Dealer.
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