Given the geographical diversity of India, last-mile connectivity has always
been a pain point for telecom operators. In the case of business centers, laying
down fiber and wiring up old buildings is a herculean task. All this, coupled
with the approvals required for digging and laying down fiber or copper, makes
it difficult to provide high-bandwidth, reliable connectivity. And, after the
broadband policy failed to unbundle the copper loops of BSNL/MTNL, private
operators have been aggressively pursuing the fiber and wireless routes to
deliver high-speed connectivity.
Free space optics (FSO) promises to solve the last-mile woes and is also
being promoted as a reliable backhaul technology for the carriers.
as a technology was initially used in defense (primarily in naval ship-to-ship
communications) and secure aerospace applications. It is now also an alternative
to fiber optic—based solutions in the commercial market space.
According to industry estimates, the worldwide FSO market at present is about
$100 mn. The potential, however, is of more than $1 bn. “FSO has been
popular in USA with almost 50% of the market. It is followed by EMEA with 30%
share and Asia-Pacific contributes 20%,” says Jeff Bean, director global
marketing, LightPointe. According to statistics, there are 750,000 large
business buildings in the US, of which only five% are connected to fiber, but
over 70% of which are within one mile of at least one of the buildings that is
connected to fiber.
In India, though pilots and testings have been carried out, deployments have
been few. On the enterprise side, Krone has deployed this technology from
Optical Access, an Israel-based company, at its Chennai-based Orchid Chemicals
and Pharmaceuticals. Bharti is said to have tested and deployed this for its
backhaul. The technology for this was provided from SONAbeam, through Netware
Technologies India. “The installations are primarily for mobile wireless
backhaul. However, enterprise building-to-building opportunities are starting to
emerge,” adds Bean.
The Tech Side
Free Space Optics, also called free space photonics (FSP) or optical
wireless, refers to the transmission of modulated visible or infrared (IR) beams
through the atmosphere, to obtain optical communications. Like fiber, FSO uses
lasers to transmit data, but instead of enclosing the data stream in an optical
fiber, the data is transmitted through the air.
FSO transmits invisible, eye-safe light beams from one ‘telescope’ to
another, using low-power infrared lasers in the terahertz spectrum. The beams of
light in FSO systems are transmitted by laser beacons towards highly sensitive
photon-detector receivers. These receivers are telescopic lenses capable of
collecting the photon stream and transmitting digital data containing a mix of
Internet messages, video images, radio signals, or computer files. Commercially
available systems offer capacities in the range of 100 Mbps to 2.5 Gbps, and
demonstration systems report data rates as high as 160 Gbps.
Will It Replace Fiber Optics?
FSO, as a technology, has all the potential to compete with the optic-fiber
cable. FSO is easy and fast to deploy, cost of deployment is less, apart from
that, no spectrum clearances, charges, or permission is is a hinderance. An
estimate by LightPointe says (according to a media reports), in India, the 10 km
range connectivity in STM 1 mode, which provides 155 Mbps of bandwidth over
fiber optic connectivity, will cost around Rs 75 lakh; while FSO connectivity
for that will cost around Rs 25 lakh.
Despite the benefits, FSO is not seen to be on its way to completely wipe out
the optical fiber. Rather, both the solutions are seen as complementary to each
other. FSO works well for connecting buildings within a limited area, typically
within a 4 km radius.
Similarly, for the carriers this works well where line of sight is available
but other options like digging for cables are not viable. In fact, VSATs give it
strong competition, when it comes to wide-area connectivity.
Lest One Forgets
The biggest drawback for FSO is that the performance goes down in extreme
weather conditions. Being a line-of-sight technology, interference of any kind
(like water, snow, radiation) can pose problems. Under foggy conditions, its
efficiency levels become doubtful. FSO systems can transfer high-speed data and
have common link for distances within 1—2 km, but inclement weather can reduce
this to 500—1000 meters. The laser beam that carries data for an FSO link is
adversely scattered by the water droplets in fog, and cannot reach a remote
terminal more than about 200 meters away. India has a tropical climate, with
weather conditions varying from extreme heat to heavy rains and thick fog. All
this casts a shadow on FSO adoption rate here.
Also, it is a very high-cost technology and systems for one deployment cost
around $7000, as a one-time capital investment. Companies promoting this
technology say, a comparison with low-bandwidth wireless options makes it appear
costly but the actual cost-per-bit analysis shows it to be less expensive.
“It’s a matter of supply and demand. If you demand high bandwidth, but
can’t find a supply, you’re sunk. We supply high-bandwidth (on a par with
optical fiber cable) that no other low-bandwidth or licensed wireless can
remotely match it,” says Bean. To overcome the cost factor, companies are
working to launch low-cost entry-level systems by 2006.
Free Space Optic Security
Wireless, by its nature, is perceived to be insecure. FSO emits infrared (IR)
beams for communications. To intrude these, beams have to be tapped. But, being
a duplex technology, it would require tapping devices to be on both ends,
increasing the chances of the intrusion being detected. Determining the size of
the beams and putting nonreflective surfaces around the equipment reduces
chances of these being tapped. Also, the time-tested method of encrypting the
data traveling over FSO ensures greater security.
Another concern in the case of beam-based technologies is that the beams may
miss the target equipment or spill beyond them.
FSO has all the properties needed to fulfill the rising demand for higher
bandwidth solutions to meet the needs of corporations and individuals. If minor
irritants are removed, it can augment the legacy WAN technologies in providing
secure, redundant links between corporate resources, the Internet, and the
FSO Equipment Providers LightPointe Terabeam Optical Access AirFiber Cablefree Solutions fSONA Systems PAV Data Systems Plaintree Systems
#402, 6-3-676/1 Durganagar Colony, Panjagutta,
Hyderabad —500 082; Phone: 91-405-5165133
8000 Lee Highway, Falls Church, VA, 22042;
Phone: +1 888-297-9090
MRV Communications, Inc. Corporate Center
20415 Nordhoff Street, Chatsworth, CA 91311
16510 Via Esprillo, San Diego, CA 92127
Cablefree House, 1 St. Clare Business Park, Holly Road
Hampton Hill, Middlesex TW12 1PZ UK
Phone: +44 (0)20 8941 7975
1750 Tysons Blvd., Suite 240, McLean, VA 22102 USA
Suite B-08-06, Block B, Plaza Mont ‘ Kiara
No 2 Jalan 1/70C, Mont ‘ Kiara, 50480, Kuala Lumpur
Phone: +603 6203 2010; Website: www.pavdata.com
110 Decosta Street, Arnprior, Ontario, K7S 3X1
Phone: +1 613 623 3434
FSO Equipment Providers
PAV Data Systems