are a few initial fundamental
issues that have to be resolved in order to accelerate the now imminent
reconstruction of Afghanistan. The following illustrates these issues.
within Kabul and with the outside world, both in voice and data traffic,
especially for the government in order to demonstrate the effectiveness of
government to the donor community and establish order in the processes of
governmental procedures. To provide for databases and programs in order to establish the following criteria:
To initialize the above proposal the following would have to be undertaken.
To budget for the following equipment to be bought and sent immediately to Kabul.
- Database of persons working for the government
their role and location, salary etc in order to establish a budget.
- Database of works being carried out by the government,
again to measure effectiveness, establish international tenders etc. and
therefore prepare for effective budgeting and transparency.
- Individual programs to facilitate governmental
tasks such as for the health, education, civil service , civil aviation etc.
- Database of Custom and excise controls etc.
- Database of all foreign office staff and their role
incorporating a private secure email communication facility for government.
- Database of all foreign entities and their role in
order to outline and coordinate their activity.
- Other databases as and when called for.
Sub total $323,000
~ 4 x $2500 ( Servers to house and distribute the data)
~ 250 x $550 (Pentiums for operators)
Microwave ~ 15 x $7000 (10 Mb/s up to 5 KM communication device)
~ 5 x $350 (In case there is an extended Power Failure)
~ 10 x $150 (Batteries in case there is a Power failure)
switches ~ 30 x $150 (Communication and distribution devices)
~ 250 x $75 ( Desks for operators)
~ 250 x $50 (Chairs for operators)
Cable cat 5
~ 3Km ~ $1500 (cabling required for buildings)
Software ~ $30,000
(Operating Systems, Security, Databases, Intranet etc)
above list is preliminary and is not exhaustive, but will establish for a
private WAN (Wide Area Network) for the governmental buildings only. The 250
operators can be anywhere with the buildings in Kabul. No wiring is required
between building and data interception will be practically impossible. Once
established the ability for the government to access data immediately will be
available. In order to connect to the outside world, the Intelsat facility
would have to be re-installed at Telecom House Kabul. This will require for a 5
Meter Antennae and
other equipment so as to establish :
Additionally, an official Afghanistan Website
should be established, to give accountability and information, feedback and
establish direct data communication with Afghans abroad, with the ability for
those Afghans to write proposals, get direct information etc etc. ( The Website
and public domain data will have to be housed outside Afghanistan initially and
be updated from Kabul)
Equipment and Technology
Spread spectrum radio is a lower cost,
convenient way to connect LANs between buildings . Spread spectrum links come
with a wide range of performance availability, from 1 Mbp to 100 Mbps, and
operate in the license-free ISM (Industrial, Scientific and Medical) bands.
Spread spectrum radio is quick to implement and can be a very effective
alternative to fiber or telephone company connectivity.
To obtain the
most out of the system you choose, the quality of the installation is paramount.
A clear signal will allow the system to perform better because packets do not
have to be retransmitted. Retransmissions that eat up bandwidth need to be
avoided at all costs.
Most spread spectrum products may be considered
customer-installable when there is a clear line of sight (LOS) between
buildings. Typical, easy installations are across the parking lot or down the
street. At the same time, customer installed systems are sometimes a frustrating
experience or more difficult than they need to be due to a lack of knowledge
about the techniques professionals use. The longer the path of transmission, the
harder it gets. To start out on the right foot, a path analysis is a
The path analysis includes: the determination of line of
sight, identification of potential obstacles, calculation of path loss, power
required to make a good link and definition of the appropriate
Defining Line of Sight
LOS, or line of sight,
means just what it says ... antennas can see each other. It does not mean that
you can see a sparse outline of the target building through a forest of trees or
that you know where the building is even though you cannot actually see it. For
longer distances, clearance above objects at the centre of the transmission path
becomes important. The centre path of the signal would be found if you were to
imagine taking a string and connecting the antennas end to end. Clear line of
sight includes clearance below the string and above all objects so that the
radio signal can propagate without reflection over the path. A rule of thumb is
to have 12 feet per mile of clearance at the centre of the path between the two
points you are connecting. How can you obtain line of sight? The best way is to
get on top of the building and look before you buy. Most often, if you can see
the building or part of it, there is a way to obtain line of sight. Poles or
towers can be installed or you can hop to a structure that is a high point that
can see both buildings to repeat the signal. In many cases permission to mount
an antenna is only a phone call away. For example, five schools in Illinois use
two local commercial grain elevators to repeat a signal to connect to the
Much Power Do I Need?
In the U.S. power is limited for
unlicensed ISM bands to 36 dB or 4 watts effective rated power (ERP). The ERP is
measured by adding the dB's from the radio plus the gain from the antenna minus
the losses from cable, connectors, lightening arrestor and filter, if any.
Decibels or dB's are simple in concept but confusing for most to determine.
Antenna gain is a measure of the directionality of the antenna or how narrow the
transmission beam is when it focuses the energy from the radio. The more
directional an antenna, the more likely it may be used to overcome poor line of
sight clearance or radio interference and the greater the achievable distance. A
radio's receiver sensitivity or receive threshold is key in the professional
path analysis to determine power requirements. Receive threshold is the lowest
signal strength at which a radio can differentiate its partner's signal and
interpret the results of the transmission. Receive thresholds for spread
spectrum radio are generally about -80 dB or .00000001 milliwatts. It is
difficult to imagine how a device can pull from the air, identify and understand
such a small amount of energy travelling at the speed of light, but that is the
miracle of radio. Given the small receive power levels available to make the
connection, it is important to align antennas for maximum signal strength.
Better wireless systems can identify relative signal strength at the base
station using built-in diagnostics.
In summary, implementation of a
spread spectrum wireless link can have many benefits but, unless you are
shooting across the street or down the block, professional installation may pay
for itself in a faster link, less hassle and greater
usable portion of the radio spectrum is huge ranging from approximately 6 kHz to
300 GHz. Because radio is so well suited to information transmission, however,
almost all of the spectrum is already reserved for specific uses. Alas, because
bandwidth is so scarce and valuable, the frequencies allocated for unlicensed
networking are what one might call junk frequencies ones commercial users are
unlikely to want. The 2.4- GHz band, for example, is subject to interference
from microwave ovens, and the signals have difficulty penetrating trees, heavy
snow, or anything at all that contains water. (the water absorbs a portion of
the signal and is heated, just as in a microwave oven.) The 900-mHz band is
often plagued by interference from medical and scientific equipment, cordless
phones, wireless stereo speakers, and similar devices. Unlicensed users of the band are considered
to be secondary users. They take a back seat to licensed, or primary, users, who
can transmit stronger signals and are subject to fewer restrictions. A
high-power primary user such as a TV station or a vehicle location system can
render an unlicensed frequency band useless to anyone else in the vicinity,
including wireless LANs. Unlicensed users have no recourse - even if they've
already spent tens of thousands of dollars on wireless networking
equipment. The requirements imposed by
the regulations on unlicensed wireless networking equipment are relatively
simple. First, the strength of the signal is limited-usually to less than I
watt. Second, the signal must be transmitted using one of two spread-spectrum
methods. The signal must either be spread out over a certain range of
frequencies or hop among a certain minimum number of narrow slots each second.
SPREAD SPECTRUM HISTORY &
The idea of spread-spectrum radio transmission was proposed by the
US military who was seeking ways to prevent radio signals from being monitored or
blocked by hostile parties. The two inventors came up with the notion of
changing the frequency of a transmission at regular intervals faster than the
enemy could retune. A special receiver
that knew the frequency-hopping pattern could follow it and pick up the entire
transmission. The hopping patterns were controlled by the punched holes in piano
rolls became known as frequency-hopping spread spectrum (FHSS).
Later, as digital logic became popular, an- other kind of spread spectrum was
developed direct-sequence spread spectrum (DSSS). In this method of
transmission, the signal does not hop from one frequency to another but is
passed through a spreading function and distributed over the entire band at
once. DSSS usually provides slightly higher data rates and shorter delays than
FHSS, because the transmitter and receiver don't have to spend time retuning.
Both FHSS and DSSS are resistant to interference from conventional radio
transmitters. Because the signal doesn't stay in one place on the band, FHSS can
elude a jammer – (a transmitter designed to block radio transmissions on a given
frequency). DSSS avoids interference by configuring the spreading function in
the receiver to concentrate the desired signal but spread out and dilutes any
radio is good at dodging interference from conventional sources – (signals that
stay in one narrow area of the frequency band and don't move. it doesn't always do as well when there are other spread
,spectrum systems operating nearby, though. The more frequency-hopping
transmitters operating on a band, the more likely it is that one or more of them
will hop to the same frequency at the same time, garbling data that must be
retransmitted. DSSS is better at resisting noise up to a certain point. However,
if the combined interference throughout the band rises above a certain level,
throughput dramatically drops-nearly to zero. Unfortunately, it only takes a few
nearby FHSS systems to cripple a DSSS system. On the other hand, because a DSSS
system is always transmitting on every frequency in the band, a nearby FHSS
system may be unable to find any clear channel to hop to. In the presence of
interference, FHSS usually degrades more gracefully than DSSS, but neither works
well when competing at close range.
antennas can sometimes help a node focus on the system with which it must
communicate and ignore interference from others. However, as a general rule,
when two transmitters compete for the same bandwidth, the one that expends more
energy per bit of data wins the battle.
because the total energy each device can emit is limited by the FCC, the
transmitter trying to send data at the highest speed. say - 10 Mbps instead of 1
Mbps - loses. The newest equipment can be hobbled by gear that's older and
Another problem that can plague wireless networks is called the hidden
transmitter problem. Suppose a wireless network is implemented as a sort of
Ethernet-in-the-air-any node can speak as long as it doesn't hear anyone else
transmitting. This works well if all the nodes can hear one another. However, in
real life, physical obstacles sometimes prevent some nodes in a network from
being able to tell when another is transmitting.
OF BABEL If all the transmitters on a given band would follow the same protocol,
the number of collisions would be small. Unfortunately, there are many wireless
networking - each of these schemes uses a unique protocol that the others do not
under- stand. So although devices of the same type will cooperate, devices of
different types won't know how to keep out of one another's way. (Many older
wireless devices, including proprietary wireless LANs and cordless phones,
observe no etiquette at all and so will never avoid collisions.) Because the FCC
regulations do not require users of a given band to observe a common etiquette,
many devices do not cooperate even when it might be in their best interest to do
this problem is another loop-hole in the FCC regulations. The regulations limit
the strength of the signal that each transmitter can emit but don't limit the
total number of transmitters any one user can operate, nor how close together
those transmitters can be. For example, the Metricom Ricochet network, which
operates on the 900-MHz unlicensed band, uses hundreds of transmitters attached
to utility poles to provide wireless Internet service to an entire
neneighbourhoodr city. To penetrate building walls and overcome interference,
each transmitter can increase its power, if necessary, to the FCC-allowed
maximum. The result: If you try to operate wire- less networking equipment in
the same unlicensed public band, you may find your equipment swarmed by dozens
of transmitters, each cranking up the power to drown you out.
Many wireless LANs allow nodes to roam as much as 1,000 feet from the base
station. Unfortunately, the further you stray from the hub, the more likely you
are to find yourself closer to a source of interference other than your own base
station. This phenomenon sometimes causes perplexing interference problems in
city office buildings. Two tenants who each install wireless LANs on their
floors can make life difficult for one another. Likewise, a 900-mHz or 2.4-GHz
cordless phone in a nearby office can sometimes render a wireless LAN
go to A wireless Tutorial section
Design Option 11 Mbps system (802.11b)
One potential solution would
offer the Capital a shared 11 Mbps network that would connect all of the
Government buildings in the district. This scenario assumes line-of-sight.
district could mount a tower on Telecom House the estimated costs for establishing
a wireless network to all Departments would be approximately $8,000 per node for Point to Point connection using the 5800 Wavespan.
This is a one-time cost. These electronics have an expected lifetime of four
One-time installation and configuration may be estimated at
$1,000 per site (not including tower
installation, if needed).
Ongoing maintenance costs may be estimated
at $400 per year per site
the cost of a tower on which to place an antennae varies from ~ $6,300 for a
self-supported light-duty 50 foot tower, to ~ $100,000 for a heavy-duty 200 foot
tower (including installation and cabling connections, but not including
engineering analysis.) To estimate this cost more accurately, an engineering
study would be required. Engineering fees for such a study may be estimated at
Standards-based Wireless Links
This technology allows
transmission of up to 11 Mbps (actual tested systems deliver approximately 7
Mbps) to transport data traffic between multiple buildings at a time. Many
companies now offer these devices for sale and prices have come down quite
This solution was designed for data communications and cannot
carry standard analog voice or video. However, if voice and video signals are
didigitised they can then be transported (H323 standard VoIP). Most systems do not set a higher
priority for this traffic, in order that data delivery (the priority) is not interrupted.
We don't recommend attempting to send voice and video over this type of
link, however facilities for this will be available in the eventuality of a failure in Kabul Telecom , government communications will be uuninterrupted
There are proprietary variations on these systems that add one or two
T-1 emulated circuits at extra cost.
Higher bandwidth wireless
This solution costs between $5000 to 23000 depending on the distance required.
The Wavespan brand model Stratum 100
is representative of a high-bandwidth radio frequency design that uses newly
available unlicensed frequencies. Although Afghanistan does not have such restrictions, the rest of the developed nations have airwave restrictions and designs have been appropriately incorporated to adhere to those standards
This system can carry 100 Mbps full duplex
data together with two (2) T-1 type interfaces for voice or video applications
and has a range of up to five (5) miles. The T-1 feature is a distinct advantage
over other wireless options if the government chooses to use compressed video (for
videoconferencing or training) among buildings.
Poor weather conditions would
not affect this system's operation.
A typical two-building interconnection
would cost $22,000 (latest price), including installation (but not tower.) , for a total of $110,000. If one
or more towers are necessary,
Due to costs for the amount of bandwidth, if the government desires
greater than 11 Mbps bandwidth, we recommend a fiber solution to be installed in the future, and have the initial
wireless as a backup.
An alternative would be to use a cheaper system from Lucent Technologies.
LUCENT ORINOCO RADIO BACKBONE is yet another RF device for point to point communications. KIT
Point-to-Point Radio Backbone KitThe Point-to-Point Radio
Backbone Kit is an easy to install, highly reliable 11 Mbit/s
building-to-building Wireless LAN connectivity solution. The kit includes all
the necessary hardware, software and management components needed to establish a
licence free 2.4 GHz wireless LAN bridge that spans up to 6 miles under clear
line of sight conditions. A low cost solution relative to regulated frequency
Easy to install and manage the point-to-point kit offers full
interoperability with existing and new LAN technology. The advanced technology,
including full routing functionality, offers all the benefits of 802.11b, as
well as superior radio technology that delivers unbeatable performance resulting
in superior range and throughput.
- High performance 2.4GHz integrated 11 Mbit/s radio
- 128-bit key security using RC4 encryption
- Adaptive Dynamic Polling
Enables a more reliable wireless link in noisy
- Protocol Filtering for bridged protocol
Filters traffic according to
- Transparent VLAN tagging
Will pass compliant Virtual LAN addresses,
therefore operates as a standard connection
- Continuous Signal Quality Monitoring
Can test RF signal level, noise
level and signal quality using a built in remote Point-to-Point testing feature.
- Remote Wireless Link Analysis
Can determine the performance of the
connection via remote analysis from a single location.
- Low Cost Solution relative to regulated Frequency Products
reliable - more economically viable than a regulated frequency product solution
- No Governmental Frequency Licensing required
The Point-to-Point Radio
Backbone Kit operates in the unlicensed 2.4 GHz Radio Frequency Band.
- Factory Pre-Configured for Network Bridge Operation
Enables users to
easily, quickly, and economically install a wireless LAN bridge between two
- Wide coverage range of up to 6 miles
- IEEE 802.11b compliant
ORiNOCO is the worlds' most popular wireless LAN
Technology Due to its superior receiver sensitivity (ears) and resilience to
microwave interference ORiNOCO has proven to be the best 802.11b radio in the
industry, providing unbeatable performance results in range and throughput.