[HOT] Smartphones using wifi in the field If you ain't in the field or techie ignore this post.

john whelan jwhelan0112 at gmail.com
Mon Feb 8 23:54:55 UTC 2016

For my sins I used to work as a technical evaluation specialist and the
first thing we used to do is to identify the user requirements.

I'm seeing different groups have different requirements here and cost is a
major driver.

So to start with where we have a large number of clients ie refugee camp
rate hardware, ie a mixture of Android, Apple, old PCS and laptops running
windows or LINUX we want client software that can run on any of these.
We'd like voice and texting, file transfer and email would be nice.

The second group want to locally transfer files from a laptop to
smartphones / laptops.

The third group would like to transfer files over much larger distances ie
full Internet access on unreliable connections.

The fourth group would like Internet access in remote locations.  Probably
there is some local traffic that doesn't need to be backhauled to the

Bandwidth matters.

A simple text message takes up the smallest amount of bandwidth,

Email without attachments comes next, use something like gmail app to work
off line rather than use the web interface. Gmail has an off line mode with
​a C​
​app addon ​
under windows or use thunderdbird.

file transfer, use pkzip or 7zip to compress your files before sending them
by the way, 7zip is probaly best they both include a CRC which shows the
file was transferred in full.  Typically this can be done slowly so the
traffic load isn't that bad.

Web sites can be not too bad or full of adverts and videos, Firefox with
noscript plugin can reduce the load.

Voice and video need priority so not only are they more demanding but they
need bandwidth as well.

So we're after cheap and reliable, out of cheap, reliable and fast it's
more pick any two.

We can do peer to peer texting with the latest Apple ipads.  It's simple
and it works.  The hardware is not cheap.

Nothing at the moment does wifi peer to peer on Android above 2.2.  Please
ask Google for the functionality ie someone showed me this on an ipad how
can I do on a NEXUS 9 or do I need to buy an ipad?

Bluetooth is available but its hard work for voice
the range and bandwidth do not compare to wifi.  Wifi doesn’t like leaves
especially wet ones by the way.

Telcos use different frequencies to make smartphones connect to the web.
There is also satellite phones, the last two we’ll rule out on cost
grounds.  However smartphones can send data over text messaging, text
messaging get sent in the packet that says “Hi I’m here by the way” to the
network so the cost to the Telco is not very high, hence unlimited text
plans, hence Franz-Josef’s comment.

A laptop running win 10 can normally function as a wifi hotspot but the
range will be limited and because its doing other things the speed
available isn't the greatest.  It maybe enough for some basic things
though.  Plugging in a portable router or hub should give you more muscle.
The TP-Link 3020 fits in the pocket and its fairly inexpensive.

SERVAL, looks good to start but then if you read further they mention they
need another $2,000,000 to tidy it up.  Also it is limited by the need to
have wifi hubs, the ones they are suggesting are portable but to be honest
for range nothing beats something with a wifi aerial and for preference
three.  The mesh extender
their wifi hub
looks as if it needs a fair bit of technical skill to set it up, for
example I’m not sure I’ll manage it and I have quite a lot of experience in
this sort of thing.  SERVAL will work with a conventional wifi hub or
router by the way.  But there again so will a lot more software.

SKYPE for example when it was first written would run on any network, its
only recently that Microsoft have made it call home before connecting but
if SKYPE used to be able to do it before it was improved then other
unimproved software will do it now, Mumble for example but there are others.

It’s always nice to see what has worked in the past.  In the New York
flooding it was a Commotion mesh network that provided wifi Internet
service to smartphones using
​external aerial stuck on a the top of a building.  Commotion mesh networks
have been connected via HAM radios by the way and the Commotion mesh
network guys have a lot of experience of this stuff.  Voice and mesh
networks are not a good match by the way, its more difficult to give voice
the priority it needs over a mesh network.  This is also a consideration
when looking at SERVAL.  Mumble for voice has been run over a Commotion
network, its used by HOT already I need to check out the client to client
rather than conference mode.
​ ​
Strangely enough PBX software looks interesting, Asterisk is opensource,
public domain, very stable and can use Internet or IP phones as clients.
This means anything that can run a SIP client
and there are lots of them
can use voice.  I’m looking at trying to run this software on a mil grade
laptop connected to a pair of hubs or routers
​, just to play with. For a refugee camp scenario that might work
especially with voice mail.

For the second group a conventional wifi hot spot or laptop with router,
the portable ones will work off the USB laptop connection, the bigger ones
you’ll need a separate power supply.

Third group is more management, send at quiet times, 20:00 - 24:00 is the
worst time to send traffic, 5:00 is typically a good time.  Laptops can be
programmed to call home at a certain time.

The fourth group unfortunately is going to depend on a number of factors.
What is available locally?  Village Telco have experience and have
addressed a number of issues.  They have a support forum as does
Commotion.  A mesh network based on Commotion practices may work in some
locations.  Mountainous ones spring to mind using directional wifi aerials
but it needs technical expertise to set up and maintain.

​Cheerio John​

On 8 February 2016 at 10:35, Franz-Josef Behr <
franz-josef.behr at hft-stuttgart.de> wrote:

> An alternative could be using text messages in additional.
> At our University a student is just finishing his Master thesis. He
> developed a framework for the collection of point based data based on
> Internet AND cellular network (based on ideas provided by Harry Ferdiansyah
> from Indonesia). In the latter case SMS text messages are used for the
> transfer of information. The information chunks which can be submitted are
> based on a configurable thesaurus to assure consistency and further
> automatic processing.
> The data transfered using Internet or cellular network are stored in a
> server-based MYSQL dbms.
> Regards Franz-Josef
> Am 03.02.2016 um 15:02 schrieb Mhairi O'Hara:
> Cheers John! We're collecting data on financial services, education and
> health facilities in Eastern Uganda and are looking for sharing solutions
> that don't involve the internet. With up to 50 students at times, sharing
> files via usb sticks and external hard drives is not ideal as it can be
> time consuming. Will look into the setup to see if it could work for us
> here.
> Mhairi
> On Wed, Feb 3, 2016 at 3:00 PM, Katja Ulbert <mail at katja-ulbert.de> wrote:
>> Thanks for this valuable information, John!
>> On 31/01/16 22:34, Pete Masters wrote:
>> Really interesting, John.... Thanks for the post. Just conducted training
>> in DRC on data collection and base mapping. We tried to focus as much as
>> possible on offline solutions. Wish I'd read this before we'd been, not
>> just after! ;)
>> Pete
>> On 31 Jan 2016 20:35, "john whelan" <jwhelan0112 at gmail.com> wrote:
>>> I've been playing around with Serval software on Android.  Ideally it
>>> needs a wifi mesh set up using multiple firmware modified TP-Link MR3020
>>> portable routers with custom software connected to a small radio device
>>> which turns it into a mesh extender.
>>> The original concept was to turn the smartphone into a router but the
>>> latest Android software well anything above 2.2 denies access to do this.
>>> Besides which rooting the phone in this manner is not good from the
>>> security point of view.
>>> However if you are running Windows 10 and your Laptop supports it, most
>>> should, you can turn your laptop into a wifi hot spot that other devices
>>> can connect to. Note you should not need to be connected to the Internet
>>> for this to work.
>>> Translation Android smartphones running Serval within say 100 meters of
>>> the laptop  can now talk to each other.  I haven't tried a phone call, I
>>> don't have two Smartphones to hand, but messaging certainly works.
>>> You should also be able to transfer files certainly from one smartphone
>>> to another and if Serval doesn't support file transfer to the host laptop
>>> there are other apps around that do.  So things like the latest maps for
>>> Osmand etc can be brought down once to the laptop then propagated out to
>>> smartphones or a smartphone sent by mail, mule etc to the wifi hub can then
>>> connect and distribute files etc.
>>> I haven't looked at the implications of interconnecting laptops perhaps
>>> with cat 5 cables and although phone calls should be fine across one wifi
>>> hub theoretically each hub used in the hops adds a small delay so voice
>>> quality over multiple hops may not be ideal.
>>> Cheerio John
>>> _______________________________________________
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>>> HOT at openstreetmap.org
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> --
> Mhairi O'Hara
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> Email: <mhairi.ohara at hotosm.org>mhairi.ohara at hotosm.org
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