AW: Order of functions to transmit and receive using layer1

historical

hi,

>     I was wondering how to transmit and receive using layer1.  I have 
> been reading some of the gsm specs.   I have been looking around in
the 
> source code a lot, and there many functions that are used for transmit

> and receive.  Which are the right few to use?

there are only two types of data between L1 and L2: data frames and
channel request burst. all the other functions control the radio and the
channel in which to communicate. the layer 1 is controlled by the radio
ressource protocol (gsm48_rr.c). in order to understand the channel
multiplexing, you should read GSM TS 05.02.

> Is there any way to send
> a text message to a different phone by simulating a base station?

osmocom is not (yet) able to control baseband hardware to act as a BTS.

> Do I 
> need two phones or one phone to transmit and receive as a base
station?  

in order to have more than a BCCH, you need two phones. one phone is not
able to send and receive at a time. continuouly transmission is required
for other phones to find a cell.

> Is there any way to make a half duplex base station on a BCCH channel 
> with only one subscriber phone at a time, and what would that entail 
> code-wise?

you can limit the number of active calls by limiting the number of
channels on the BTS, but you cannot limit the number of phones camping
on the BTS.

> Would it be legal to run a very low power base station in 
the USA on a different unused cellular band/frequency?

you need to check the FCC for laws and test licenses.

> I have a lot of 
> free time since I do school at home and I could probably help develop 
> some new parts of the osmocom-bb project if you want me to.  I know C,

> some x86 assembly, and a few other languages.  I have also had
practice 
> fixing compile-time errors, and bugs in code.  I apologize if this is 
> too many questions. You don't have to answer them all if you don't
want to.

if you are really interested. you should start reading with TS 04.08.
this is what i did. it describes all the three "layer 3" protocols. 

Thank you for helping,
Calvin E. Balke