[huridocs-tech] Radio E-mail in West Africa

[***Originally posted on the Global Knowledge for Development (GKD) 
listserv, Mod.***]

I came across this interesting piece on internet connectivity via high
frequency radio in western Africa on the DigitalDivide list. Though this
finds its birth in Africa, I think it has some implications for rest of
the world especially developing countries. Its longish so I suggest you
visit the site for the complete article. Hope you enjoy it.

Warm regards,

Ashish Kotamkar
(ashish@mithi.com)

*******************************************************

Radio E-mail in West Africa: The Complete Version
http://www.linuxjournal.com/article.php?sid=6299

Deep inside the warm green interior of Guinea, centered in the frontal
lobe of West Africa, field personnel in the widely scattered
village-towns of Dabola, Kissidougou and Nzerekore now enjoy access to
regular internet e-mail, directly from their desktops. Here we have
bridged the digital divide, and there isn't a telephone line or
satellite dish in sight. Instead we are moving the mail over distances
of hundreds of miles--over jungled mountains and high palmy
savannahs--through wavelengths of high-frequency (HF) radio. Our project
is called Radio E-mail, and here is its story.

The Republic of Guinea is a cashew-shaped nation with Atlantic view
property, 10 degrees north of the equator in west West Africa. It is a
beautiful and resource-rich nation, with an total land area about the
size of Oregon. As far as African countries go, Guinea is a calm pocket
of peace and stability, and it generally doesn't attract a lot of
attention from beyond its own borders.

But Guinea has quietly played a heroic role in the theater of world
events in recent years. It provides a safe and welcome refuge for as
many as half a million people displaced by brutal wars and civil
upheavals in the neighboring countries of Sierra Leone and Liberia.

The International Rescue Committee (IRC) has one of their largest
operations in Guinea, providing services and support to a population of
up to 200,000 refugees quartered in many camps established throughout
the country. I became involved with IRC when my wife accepted the
position of Country Director for the program in the summer of 2001. Soon
we were traveling on an inspection tour of the camps, making the long
road-trip to visit the program's three field offices up-country. Our
first destination was a distant and dusty village, delightfully named
Kissidougou--frequently called Kissi in the local vernacular.

Traveling outside the capital city of Conakry, one immediately finds
that Guinea has little infrastructure, especially in the way of
electrical grid and telecommunication systems--to say nothing of
Starbucks and broadband access to the internet. So IRC field offices
must provide their own infrastructure: diesel generators for electricity
and high-frequency (HF), two-way radio sets to communicate with other
offices and mobile units, up to hundreds of miles apart.

Expecting this isolation and general lack of connectivity, I was quite
astonished when we arrived in Kissi. Here I found the radio operator
using his equipment to make a binary file transfer from his desktop PC
to another field office, wirelessly!

This capability surprised and intrigued me. On top of the operator's
radio set, connected to the serial port of his PC, sat a dingy black box
simply labeled 9002 HF Data Modem. I noticed the operator used a
proprietary, MS-DOS program to make his file transfers, but I
immediately began wondering: if this device is truly some kind of modem,
moving binary data over the ether of radio, why couldn't we set it up
with Linux and network with PPP connections as well?

After a little research and testing, I soon confirmed this equipment
could indeed form the basis of a wide area network, providing full
access to internet e-mail via the Conakry office for all personnel in
each of the three field offices. Moreover, since IRC owned most of the
equipment already--and since we would be using Linux and other freely
available, open-source software--the system could be implemented at
negligible cost, with no increase in operating expenses. For the price
of some network cards and category 5 cable, we could connect our bush
offices to the rest of the world. I developed a design and specification
for the system, and the project we call Radio E-mail has been
continuously operational since January 2002.


HF Goes the Distance

If you have been making the move to wireless lately, most likely you are
working with the microwave, high bandwidth frequencies of 802.11b. If
so, you know that on a clear day you maybe can get a line-of-sight
connection out 10 miles or so. That surely won't do for the vast
distances and wild terrain we need to cover in rural Africa.

HF radio is another animal. Its longer waves roll out across the
landscape, reflecting off the ionosphere to follow the curvature of the
earth. This gives HF signals a range in the hundreds of miles. From
Conakry to Nzerekore--IRC Guinea's most distant field office--HF easily
covers a straight-line distance of over 375 miles (600 kilometers.) The
road that sometimes connects these two points is, of course, much
longer--a gut-slamming, spine-jamming, two-day punishment for the
damned.

So the great advantage of HF is it can go the distance, leaping the
obstacles in its path with aplomb. Now for the bad news: where HF wins
the wireless game in range, it loses its pants in data capacity. If
802.11b is considered broadband, think of HF as slim-to-none-band. The
radio modems we are using here are speced at an anorexic 2400 baud!

And wait, it gets worse. Two-way radio is the classic half-duplex medium
of communication; that is, you are either transmitting--push to talk--or
receiving, not both at the same time. This, plus the robust
error-checking protocols implemented by the modem hardware itself, means
the actual link experience is more on the order of 300 baud. Does anyone
remember 300 baud? Unless you measure your patience with radio-carbon,
your dreams of remote login sessions will be dashed and splattered. As
for on-line browsing, chat, video-conferencing and the like, well, best
to not even think about it.

Yet for classic store-and-forward applications like text-based e-mail,
the bandwidth limitation of HF radio is workable. We simply need to pay
close attention to our configuration and try to optimize as much as
possible. With HF radio, every packet is precious. .....

<snip>




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