FAQ for the Burning
Man 2009 "Papa Legba" Test Network
Administrative
- Who is doing this? This is an activity of the OpenBTS project. The
entity legally responsible for the test is Kestrel Signal Processing, Inc.. The actual
on-site engineers are David Burgess and Harvind Samra.
- Is this legal? Yes. We have an experimental license,
WD9XSP, and a consent letter from Verizon authorizing us to operate in their
KNKN224 block A cellular spectrum. We are also coordinating operations with
Commnet Wireless to prevent interference.
- How much does the service cost me? Nothing.
- What do you do for emergency calls? Nothing. We are an
experimental service and do not support emergency calls.
- Where is your camp? We are Papa Legba, placed at 4:30 &
H. Look for the WD9XSP tower. Drop by for a sticker and a tour.
Black Rock City, LLC
- Does BM-Org know about you? Sorta. The technical side of
the organization is supportive and coordinating network service for our
backhaul. Other parts of the organization are still finding out about
us.
Commnet Wireless
- Are those your trucks and towers at Frog Pond and in
Gerlach? No. That's Commnet Wireless, a commercial cellular carrier who
is providing cellular service at Burning Man this year.
- Are you going to interfere with each other? No. Commnet
will be operating in the block B spectrum under license KNKN225. We will be in
block A. We have exchanged contact information to resolve any unforeseen
problems on-site.
- What is you relationship to Commnet? None. Please do not
get us confused.
Practical
Service CapabilitiesPapa Legba's primary service is on-Playa
text messaging, the delivery of text messages between handsets within BRC. We
will also have limited support for speech service.
- Can I call the "real world"? If you do get full speech
service, you will indeed be able to call out of BRC.
- Can the "real world" call me? If you have speech service,
you will be able to receive inbound calls from VoIP carriers through the +883 iNum country code.
- Can I use my own VoIP PBX to route calls to my cellphone
while I'm at Burning Man? Yes, as soon as we know our public IP
address.
- Can I text the "real world"? You can send text to many
internet-based IM services, like Gizmo or Skype. You can also send text to
e-mail addresses.
- Can the "real world" text me? You can receive text from
many internet-based IM services, but probably not from cellular
carriers.
Using My Phone
- Will my phone work with the Papa Legba network? All
current-market phones that work with AT&T or T-Mobile will also work with
Papa Legba, even if they are locked. You can use your existing SIM, too.
- How will you know my phone number? You will tell Papa Legba
via SMS. When your handset first contacts the network, you will receive a text
message asking you to respond with your 10-digit phone number. If that process
is successful, you will receive another message informing you that you have been
provisioned in the network. That's it.
- My phone shows service but I can't make a call. Why not?
Only the first few hundred subscribers will get full speech service. Everyone
else will just get SMS. There are two good reasons for this:
1. We don't have
enough equipment for everyone to get normal speech service.
1. Widespread
speech service would change the nature of BRC in ways a lot of people would not
like. - How do I know my phone is on your network? You will see a
network ID of "001 01", "Test" or "PpaLgba", depending on your handset brand and
model.
- How can I force my phone to use one network or the other?
That depends on your phone model. We are still working on a collection of
instructions:
- Will my carrier charge me for every text message I send or receive
on the Papa Legba network? No, the Papa Legba network is a separate
isolated network from your normal carrier's network, and no charges will apply
as no SMS is being sent or received through your normal carrier.
- Will putting a Papa Legba sticker on my phone make it work
better? Probably.
Technical
- What band and technology are you using? GSM850.
- What are your specific frequencies and powers? Our
frequencies will be 870-880 MHz downlink and 825-835 MHz uplink. We will operate
our downlink at 20 W EIRP. In the uplink, the typical GSM handset has a maximum
power of 1 W, although we will use closed link power control to minimize handset
power to the greatest degree possible.
- What RF equipment are you using? See OpenBTSBM2009RF.
- What network software do you use? We use Asterisk for our
speech PBX and provisioning functions. We use a custom server for SMS. All
interfaces are based on SIP/RTP. The GSM stack itself is OpenBTS.
- What is your GSM configuration? We will operate 3 or 4 BTS
units. Each will be a single ARFCN. Each will be configured with channel
combinations V, 3xVII, 4xI. That will give each BTS unit 4 speech channels and
the ability to transfer 300-400 text messages per minute.
Miscellaneous
- Why "Papa Legba"? Papa Legba is a voodoo deity who mediates
human contact with the spirit world. Like Papa Legba, our radio equipment stands
at a crossroads between seen and unseen worlds.
- How much did this cost? The BOM cost for the full system is
about $16k. We have sponsors, though:
- Martin Pelayo is providing our 70' tower.
- John Gilmore funded part of the development of our SMS air interface and
actually wrote the SMS server himself.
- Voxbone is providing funding and most of our VoIP
connectivity.
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