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
By default RSSI on the Rx side is computed based on transmitter's
tx power and then substracting the the Rx path loss.
If FAKE_RSSI is used, then the values in there are used instead.
A default hardcoded value of tx nominal power = 50 dBm is set to keep
old behavior of RSSI=-60dB after calculations.
Change-Id: I3ee1a32ca22c3272e66b3ca78e4f67d283844c80
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
Messages on DATA interface may have different header formats, defined
by a version number, which can be negotiated on the control interface.
By default, the Transceiver will use the legacy header version (0).
The header format negotiation can be initiated by the L1 using the
'SETFORMAT' command. If the requested version is not supported by
the transceiver, status code of the response message should indicate
a preferred (basically, the latest) version. The format of this
message is the following:
L1 -> TRX: CMD SETFORMAT VER_REQ
L1 <- TRX: RSP SETFORMAT VER_RSP VER_REQ
where:
- VER_REQ is the requested version (suggested by the L1),
- VER_RSP is either the applied version if matches VER_REQ,
or a preferred version if VER_REQ is not supported.
If the transceiver indicates VER_RSP different than VER_REQ, the L1
is supposed to reinitiate the version negotiation using the suggested
VER_RSP. For example:
L1 -> TRX: CMD SETFORMAT 2
L1 <- TRX: RSP SETFORMAT 1 2
L1 -> TRX: CMD SETFORMAT 1
L1 <- TRX: RSP SETFORMAT 1 1
If no suitable VER_RSP is found, or the VER_REQ is incorrect,
the status code in the response shall be -1.
As soon as VER_RSP matches VER_REQ in the response, the process
of negotiation is complete. Changing the header version is
supposed to be done before POWERON, but can be also done after.
Change-Id: I8d441b2559863d2dbd680db371062e4f3a2f9ff9
Related: OS#4006
Since fake_trx.py can handle multiple transceivers, it makes sense
to print some info in logging messages about transceivers they
belong to. This acvieved by defining __str__() for Transceiver.
Some examples:
[DEBUG] ctrl_if_trx.py:83 (127.0.0.1:5700) Recv POWEROFF cmd
[INFO] ctrl_if_trx.py:85 (127.0.0.1:5700) Stopping transceiver...
[DEBUG] ctrl_if_trx.py:95 (127.0.0.1:5700/1) Recv RXTUNE cmd
[DEBUG] ctrl_if_trx.py:102 (127.0.0.1:5700/1) Recv TXTUNE cmd
[DEBUG] ctrl_if_trx.py:155 (127.0.0.1:5700/1) Ignore CMD SETTSC
[DEBUG] ctrl_if_trx.py:155 (127.0.0.1:5700/1) Ignore CMD SETPOWER
Change-Id: I1f706790a2da226f1418f89d2cfbb55baa6ea624
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
Vadim Yanitskiy
Oliver Smith
Pau Espin
Alexander Couzens