Radio E-mail in West Africa

["Ashish Kotamkar" <ashish@mithi.com>]

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)  

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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>