For the sake of simplicity and due to some performance limitations,
fake_trx.py does not generate TRXD NOPE indications for osmo-bts-trx
on its own. It's actually trxcon sending NOPE.req (empty Tx PDUs)
when it has nothing to send, and fake_trx.py simply converting them.
In a follow-up change [1] we remove trxcon's internal clock module,
making the Uplink burst scheduling being driven by Downlink bursts
with the respective TDMA Fn/Tn values. Given that fake_trx.py is
currently dropping bursts received for inactive timeslots, we would
get NOPE.req only for a single timeslot, the one being currently
active. This would break several testcases in ttcn3-bts-test.
Remove SETSLOT based burst filtering, so that trxcon would still be
able to generate NOPE.req for all, active and inactive timeslots.
Downlink bursts for inactive timeslots are discarded anyway.
Change-Id: Ia42550d5c2d8b49efbdf8ef0ce46b26afd1c464e
Related: [1] Ic8a5b6277c6b16392026e0557376257d71c9d230
Related: OS#5500
Remove the paragraph about writing to the Free Software Foundation's
mailing address. The FSF has changed addresses in the past, and may do
so again. In 2021 this is not useful, let's rather have a bit less
boilerplate at the start of source files.
Change-Id: I73be012c01c0108fb6951dbff91d50eb19b40c51
I intentionally do not use 'Downlink' and 'Uplink' terms in this project
because both MS and BTS transmit and receive on the opposite directions.
A burst coming from demodulator may be a Downlink or an Uplink burst
depending on the context, so we definitely need more precise terms.
Back then when I started to work on TRX toolkit, I decided to use the
'TRX2L1' and 'L12TRX' for receive and transmit directions respectively.
Now I find them hard to read, so let's replace them with 'Rx' and 'Tx'.
Change-Id: I688f24a3c09dd7e1cc00b5530ec26c8e8cfd8f7c
Related: OS#4006, SYS#4895
There are two ways to implement frequency hopping:
a) The Transceiver is configured with the hopping parameters, in
particular HSN, MAIO, and the list of ARFCNs (channels), so the
actual Rx/Tx frequencies are changed by the Transceiver itself
depending on the current TDMA frame number.
b) The L1 maintains several Transceivers (two or more), so each
instance is assigned one dedicated RF carrier frequency, and
hence the number of available hopping frequencies is equal to
the number of Transceivers. In this case, it's the task of
the L1 to commutate bursts between Transceivers (frequencies).
Variant a) is commonly known as "synthesizer frequency hopping"
whereas b) is known as "baseband frequency hopping".
For the MS side, a) is preferred, because a phone usually has only
one Transceiver (per RAT). On the other hand, b) is more suitable
for the BTS side, because it's relatively easy to implement and
there is no technical limitation on the amount of Transceivers.
FakeTRX obviously does support b) since multi-TRX feature has been
implemented, as well as a) by resolving UL/DL frequencies using a
preconfigured (by the L1) set of the hopping parameters. The later
can be enabled using the SETFH control command:
CMD SETFH <HSN> <MAIO> <RXF1> <TXF1> [... <RXFN> <TXFN>]
where <RXFN> and <TXFN> is a pair of Rx/Tx frequencies (in kHz)
corresponding to one ARFCN the Mobile Allocation. Note that the
channel list is expected to be sorted in ascending order.
NOTE: in the current implementation, mode a) applies to the whole
Transceiver and all its timeslots, so using in for the BTS side
does not make any sense (imagine BCCH hopping together with DCCH).
Change-Id: I587e4f5da67c7b7f28e010ed46b24622c31a3fdd
The burst transformation in BurstForwarder.forward_msg() used to be
done only once, so then the resulting message was distributed over
the list of connected (and active) transceivers.
This approach limits the path loss simulation capabilities, because
a reference to the same message is passed to FakeTRX.send_data_msg().
If one transceiver changes (or removes) the burst bits, the other
transceivers would not receive the original message.
Let's do the transformation individually for each transceiver,
so the original message will always remain unchanged.
Change-Id: Ia016a3a9bb6e9f17182a7168aa5a501ae9b9978b
Since the new TRXD header format has been introduced, FakeTRX needs
to be able to fill it correctly. In particular, the following:
- Modulation, which can be determined from the burst length;
- Training Sequence Code (and set), which needs to be detected
by comparing the burst bits of L12TRX message against known
training sequences (only GMSK and the default TS set for now);
- C/I (Carrier-to-Interference ratio), which can be simulated
later on, as instructed on the TRXC interface ('FAKE_CI').
The actual TRXD header version is stored in the instance of class
DATAInterface. By default (at startup), legacy version 0 is used.
The version negotiation is supposed to be performed on the TRXC
interface, and to be implemented in a follow-up change.
Different Transceivers may use different header versions, thus in
FakeTRX.send_data_msg() we need to override the original version
of the L12TRX message, and generate the corresponding PDU.
Limitations:
- NOPE / IDLE indications are not (yet) supported;
- TSC detection: GMSK modulation only.
Change-Id: I164f5ae4ce7694d6e324aab927a04e96d489ebd8
Related: OS#4006
It was discovered that using an empty list as default argument
value does result into the cross-reference, i.e. all instances
of BurstForwarder would reference the same trx_list object.
This is not an expected behaviour, let's fix this.
Change-Id: Id71185de05b0ebc5adb105b10fad2cbde5f800b1
This change is a big step towards handling of multiple transceivers
in a single process, i.e. multiple MS and multiple BTS connections.
The old class hierarchy wasn't flexible enough, because initially
fake_trx was designed as a bridge between OsmocomBB and OsmoBTS,
but not as the burst router. There were two separate, but 90%
similar implementations of the CTRL interface, two variations
of each simulation parameter - one for UL, another for DL.
The following new classes are introduced:
- Transceiver - represents a single transceiver, that can be
used as for the BTS side, as for the MS side. Each instance
has its own CTRL, DATA, and (optionally) CLCK interfaces,
among with basic state variables, such as both RX / TX freq.,
power state (running or idle) and list of active timeslots.
- CTRLInterfaceTRX - unified control interface handler for
common transceiver management commands, such as POWERON,
RXTUNE, and SETSLOT. Deprecates both CTRLInterface{BB|BTS}.
- FakeTRX - basically, a child of Transceiver, extended with
RF path (burst loss, RSSI, TA, ToA) simulation. Implements
a custom CTRL command handler for CTRLInterfaceTRX.
The following classes were refactored:
- BurstForwarder - still performs burst forwarding, but now
it doesn't store any simulation parameters, and doesn't
know who is BTS, and who is MS. Actually, BurstForwarder
transforms each L12TRX message into a TRX2L1 message, and
dispatches it between running transceivers with matching
RX frequency and matching timeslot.
- FakePM - still generates random RSSI values, but doesn't
distinguish between MS and BTS anymore. As soon as a
measurement request is received, it attempts to find
at least one running TRX on a given frequency.
Please note that fake_trx.py still does handle only a single pair
of MS and BTS. No regressions have been observed. Both new and
refactored classes were documented.
Change-Id: Ice44e2b22566b3652ef6d43896055963b13ab185
Related: OS#3667
There are multiple advantages of using Python's logging module:
- advanced message formatting (file name, line number, etc.),
- multiple logging targets (e.g. stderr, file, socket),
- logging levels (e.g. DEBUG, INFO, ERROR),
- the pythonic way ;)
so, let's replace multiple print() calls by logging calls,
add use the following logging message format by default:
[%(levelname)s] %(filename)s:%(lineno)d %(message)s
Examples:
[INFO] ctrl_if_bts.py:57 Starting transceiver...
[DEBUG] clck_gen.py:87 IND CLOCK 26826
[DEBUG] ctrl_if_bts.py:71 Recv POWEROFF cmd
[INFO] ctrl_if_bts.py:73 Stopping transceiver...
[INFO] fake_trx.py:127 Shutting down...
Please note that there is no way to filter messages by logging
level yet. This is to be introduced soon, together with argparse.
Change-Id: I7fcafabafe8323b58990997a47afdd48b6d1f357
The randomization of both UL/DL RSSI and ToA values is optional,
and can be configured from the control interface (see both
FAKE_RSSI and FAKE_TOA commands).
The command line options for enabling / disabling the randomization
were redundant, so let's get rid of them and check if the
corresponding treshold value is set.
Change-Id: I6adc13b8989ade2fab895673525c0ca17bf9b3f2
For some reason, the time-slot pass-filtering was only done for
DL bursts, but not for UL bursts. BurstForwarder shall not pass
UL bursts for unconfigured time-slots too.
Let's also print a warning if an UL burst is sent on a not
configured time-slot, i.e. before sending SETSLOT command.
Change-Id: Idb7f5b212e5814aeff8ca8bc875ad066674267cd
Previously it was only possible to configure a single time-slot
that would be pass-filtered by a BurstForwarder instance. In some
applications it would be useful to configure multiple time-slots,
so let's refactor the time-slot pass-filtering algorithm.
Change-Id: Ie1490adaf7a7c62c966aeb60c1898eaf3b5a1e84
Instead of having all configuration variables of BurstForwarder
initialized in the class heading, let's introduce two functions
for initialization (resetting to defaults) of both UL/DL params.
This would allow to reset a BurstForwarder instance from the
control interface in follow-up patches.
Let's also introduce some basic documentation for the class
fields, which were defined in the heading previously.
Change-Id: I6b1bf41cf22f01a7e7ecc91c625fb0d2bf4bfeac
This change introduces a couple of new CTRL commands for path loss
simulation, in particular a possibility to drop some amount of
bursts according to some TDMA frame period, separately for both
Uplink and Downlink directions.
Examples:
FAKE_DROP 4 - drop 4 consistent (period=1) bursts,
FAKE_DROP 16 2 - drop 16 even bursts (period=2).
Change-Id: Ib210138a03e2377c79875a4ff2f2bb58a43cfa46
Related: OS#3428
This change separates burst preprocessing (i.e. both RSSI and ToA
calculation) from BurstForwarder.transform_msg() because it's not
actually related to the message transformation process.
Change-Id: Ia7ad970593f38d9a9401975eb6dae67cd0c94e11
This toolkit has branched out into several different tools for
TRX interface hacking, and creating a virtual Um-interface
(FakeTRX) is only one of its potential applications.
Change-Id: I56bcbc76b9c273d6b469a2bb68ddc46f3980e835
Vadim Yanitskiy
Oliver Smith
Pau Espin
Vadim Yanitskiy