= What this is about =
This is an implementation of OMA SUPL and 3GPP RRLP protocols used in
Assisted GPS (AGPS). Only client (mobile) initiated case is implemented.
The package provides 2 user level executables
1) supl-client and
2) supl-proxy
and supporting SUPL/RRLP library libsupl.
== supl-client ==
supl-client connect to a SUPL server over the Internet and gets GPS
assistance (A-GPS) data, like satellite ephemeris and almanac data
from it. The received data can then be fed to a GPS receiver (assuming
the receiver accepts such data) to speed up satellite acquistion.
Usage:
supl-client options [supl-server]
Options:
--cell gsm:mcc,mns:lac,ci|wcdma:mcc,msn,uc set current gsm/wcdma cell id
--cell gsm:mcc,mns:lac,ci:lat,lon,uncert set known gsm cell id with position
--format human machine parseable output
--debug n 1 == RRLP, 2 == SUPL, 4 == DEBUG
--debug-file file write debug to file
--help show this help
Example:
supl-client --cell=gsm:244,5:0x59e2,0x31b0:60.169995,24.939995,127 --cell=gsm:244,5:0x59e2,0x31b0
The default SUPL server is supl.google.com.
Supl server may not return all assistance information if --gsm-cell
is not given. You can give some cell id to supl server but position
information returned by the server (based on the cell id) can be
overridden by --set-pos in the output. Format for this is
--set-pos=lat,lon,uncertainty
where both lat and lon are decimal degrees (N and E positive) and
uncertainty in meters.
Also if environment variable SUPL_FAKE_POS it is used as the
position estimate coming from the supl server. Format is the same
as in --set-pos.
With test options '-t 0', '-t 1' or '-t 2' you get a quick feeling
how and if things will work - if they work ;-)
== supl-proxy ==
Usage:
supl-proxy supl-server
Sets up a proxy and displays SUPL / RRLP traffic between the client
and server. Convenient for debugging and figuring out the protocol.
To use it, you must direct your mobile to use your proxy server as its
SUPL server. In Nokia N95 this is in Tool -> Settings -> General ->
Positioning -> Positioning server. In Nokia N900 such setting is also
available in the settings application.
You must also install a SSL root certificate to the phone. The root
certificate must be set as trusted certificate in the phone. In N95
just set all uses as trusted (in the certificate manager). In N900 you
must use command line tool cmcli (available in maemosec-certman-tools
package) and install the root certificate into common-ca domain.
The proxy server must be given a server certificate (signed by the
root certificate) and private key. The proxy reads them from
cert/srv-{cert,priv}.pem files.
=== How to generate keys and certificates ===
** You can skip this section if you do not use supl-proxy **
All SSL keys and certificates can be generated with supl-cert tool if
you do not have those around already.
Run supl-cert with your proxy server domain name as the only argument:
~/src/supl-1.0 $ supl-cert proxy.dot.com
It will create CA certificate and private key files ca-cert.pem and
ca-priv.pem, and proxy server certificate (signed by the CA) and
server private key files srv-cert.pem and srv-priv.pem.
File ca-cert.pem should be sent (e.g. OBEX push for N95 or simple copy
for N900) to your mobile and then installed into certificate
store. Make sure to give it SSL trust.
supl-proxy expects to find srv-cert.pem and src-priv.pem from the
current directory. CA private key ca-priv.pem is not needed anymore.
= Compiling =
== Compile without ASN.1 compiler ==
If you do not have asn1c (http://lionet.info/asn1c) available do:
~/src/supl $ ./configure --precompiled-asn1
~/src/supl $ make
~/src/supl $ sudo make install
That's it.
== Compile with ASN.1 compiler ==
You should use asn1c version 0.9.23, there are some issues with
earlier versions.
Get the asn1c source from http://lionet.info/asn1c/download.html or
clone the git repository
~src/ $ git clone git://github.com/vlm/asn1c.git
and then configure, compile and install it first:
~/src/ $ cd asn1c
~/src/asn1c $ make
~/src/asn1c $ sudo make install
You may want get rid of your distribution provided asn1c compiler
first, or at least make sure the following compilation uses this newer
version.
Then proceed with compiling this stuff
~/src/supl $ ./configure
~/src/supl $ make
~/src/supl $ sudo make install
== Fixing ASN specs ==
There is a conflict with NavigationModel which is defined by both supl
and rrlp. Rename definition and every reference to NavigationModel
with XNavigationModel in src/supl-posinit.asn.
== ASN.1 compilation from sources ==
Generation of compiled C-files from ASN.1 sources should happen
automatically with make. But if you add new ASN.1 files or PDUs you
must check and modify the Makefile in src/asn-rrlp or src/asn-supl
directory to include any new structures you introduced into ASN files.
You can give path to asn1c skeleton files to configure script as
~/src/supl $ ./configure --asn1c-skeletons /path/to/asn1c-git-HEAD
== Getting MCC, MNC, LAC and CI ==
You need to provide your position estimate to supl server as
cellular transmitter tower ids. One way to get them is to
go to the AT-command interpreter in your phone and ask for them:
at+cops?
+COPS: 0,2,"24405",2
OK
at+creg=2
OK
at+creg?
+CREG: 2,1,"59E2","31B0"
OK
at+creg=0
OK
==> you get needed values
MCC = 244
MCN = 05
LAC = 0x59e2
CI = 0x31b0
Alternatively you may setup supl-proxy on your machine and see
what your device talks to the supl server.