At both the PNF and the VNF, introduce a separate numerology field, and
pass the numerology when converting time information using macros from
nfapi_interface.h. The actually numerology is still hardcoded to 1 (as it
was before), but the follow-up commits will put a suitable numerology.
In both cases, but the numerology next to the frame/slot information.
The next commits will modify the time macros used in the 5G nFAPI code
to handle different numerologies. As a preparation, remove all the
usages of these macros where they really don't matter (e.g., don't
convert if we don't need to).
the L1 needs both a PDU (in TX_data.req) as well instructions for
the actual transmission (in DL_TTI.req) to encode a PDSCH message. In
nFAPI, it can happen that a DL_TTI.request message has been received
(configuring the PDSCH transmission), without the TX_data.request having
reached the PNF. The L1 assumes to have the PDU.
To avoid problems, ensure that only the pair of DL_TTI.req/TX_data.req
is delivered. Otherwise, drop either message.
nFAPI has a mechanism to segment messages that are too big for transport
over a given medium (see e.g. SCF 225, section 2.3.2).
The maximum segment size of 10000 makes that for larger payloads, e.g.
TX_data.request, many small segments are to be sent. This can create or
increase delays on the transport. On the other hand, the currently only
available transport mechanism, UDP, allows to transport packets of up to
almost 65535 bytes. Correspondingly, increase the maximum segment size
so that less segments are to be created, and potentially, less delay is
to be incurred. # Please enter the commit message for your changes.
Lines starting
Avoid delays in tx_data.request handling by avoiding big malloc()s and
copy operations. Reimplement function to (1) peek the frame/slot
numbers, (2) decide on buffer, and (3) unpack directly into
pre-allocated memory.
Co-authored-by: hsum <ming-hong.hsu@eurecom.fr>
Co-authored-by: chenyi <Yi-Quan.Chen@eurecom.fr>
Co-authored-by: Rúben Soares Silva <rsilva@allbesmart.pt>
The next commits refactor the rx handling of messages in the PNF. To
efficiently handle them, provide a "peek()" function that gives us the
frame/slot for which a message is destined. This allows to decide if a
message is on time and select a destination buffer, before unpacking it
completely, avoiding copies.
The time that a message between PNF/VNF to arrive depends mostly on the
transport. To allow for some delays, there is a slot_ahead time, during
which the VNF is allowed to schedule and send instructions to the PNF.
This can be multiple slots; the 1ms hitherto given might typically too
short. Increase to 10ms, to encompass a wider range of slot_ahead times.
Make the corresponding log message of when old (stale) message are
removed a bit clearer with respect to times.
This is the first commit in which nFAPI works. Follow-up commits improve
performance.
The function now utilizes simpler variable names and logic to determine
if a given NR P7 request falls within the timing window.
The logic for determining if a request is within the timing window is as follows:
- The function calculates the absolute difference between the current
and received SFN slots, taking into account the possibility of
wraparound.
- If the absolute difference is greater than half of the maximum SFN
slot value, it subtracts this difference from the maximum SFN slot
value to get the actual difference.
- The function then checks if this difference is less than or equal to
the specified timing window. If it is, the request is considered to be
within the window.
Additionally, the commit updates the function signature to return a
boolean value for better readability and consistency.
Changes made:
- Simplified variable names for readability
- Improved logic for handling wraparound scenarios
- Updated function signature to return a boolean value
Co-authored-by: Rúben Soares Silva <rsilva@allbesmart.pt>
If VNF and PNF are deployed through different processes, it's crucial to
maintain synchronization and ensure smooth operation. This commit
addresses the need to keep the VNF slot ahead of 2 (as required for
network deployment), while ensuring that PNFs wait appropriately to
avoid overtaking the slot. Specifically, this involves measuring slot
duration and implementing a wait mechanism to ensure that PNFs do not
exceed a slot duration of 300 microseconds. This ensures proper smooth
operation, especially in the case of RFsim.
Refactor pnf_phy_ul_dci_req(), pnf_phy_dl_tti_req(),
pnf_phy_tx_data_req(), pnf_phy_ul_tti_req(), to use L1 functions to
"load" L1 jobs to be executed, via L1 functions.
This function applied an sf_ahead, bigger than the actual slot
indication message sending (so a message could NEVER arrive on time!).
Reduce to zero, because this is when it should arrive for us.
Upon reception of FAPI UL messages (e.g., RACH.indication), those
messages are put into queues, to be delivered in a single call,
NR_UL_indication(). Call the scheduler to trigger processing in UL.
Note that ideally, these queues should not exist at all, and messages
should just be delivered asynchronously, as this would lead to less
copying of messages. Currently, we fulfill the scheduler interface
instead.
Important! Trigger UL after having run DL scheduler and sent the
messages, to ensure short delay between Slot.indication, and the
response to those messages.
The previous designs seems to do:
loop {
poll_ind_queue()
if (msg)
scheduler;
pselect() on messages;
handle_message {
if slot_ind
put_ind_queue()
}
}
So basically, we artificially put a queue for slot indications in the
middle, but still handle it in the same thread(!). This for some reason
results in a big slow down if the PNF runs faster.
Now, we just do pselect(), waiting for messages. We handle the slot
indication immediately (the schedule should take some microseconds),
then return to pselect().
This is to align with monolithic/FAPI, where we get slot indications in
each slot. In the nFAPI, this is replaced by timing information, such
that the VNF ticks automatically, and gets indications from the PNF on
early/late messages. The timing information handling is not implemented
in the present nFAPI implementation. Instead, we adopt the FAPI behavior
and send timing information in every slot, abusing it to be a slot
indication.
There is no need to add the PNF in nr_start_resp_cb(), because it has
already been done in nr_param_resp_cb(). This might be wrong, because 4G
does it only in nr_start_resp_cb(), but for the moment, since it is also
used in nr_param_resp_cb(), avoid the double add.
The same function is called in nr_start_resp_cb(), why there and not here?
At reception of nr_param_response, we receive the remote PNF information
on PNF/VNF. We have to store it.
In nr_start_response, it might not be correct and/or can be taken out.
The next commit will remove it.
Add a small FAPI Hex parser utility
Adds a small FAPI hex parser utility nfapi_hex_parser, that takes in a FAPI
message hexdump, either from the command line or a file, unpacks it and prints
the contents out to the console.
The functions to print the data to the console were added alongside the existing
utility functions, for both P5 and P7 messages.
This allows the user to quickly check if a message has the valid format to be
unpacked in OAI.
The file examples.md contains some examples of execution and output.
This utility is compiled alongside the NFAPI_LIB, as such, it is compiled
whenever we compile nr-softmodem, or any other target that uses the NFAPI_LIB.
Add utility functions to print the FAPI messages contents
Add dump functions for DL_TTI.request PDUs, remaining message structures to be finished
Add file examples.md with some examples on how to use nfapi_hex_parser
Robert Schmidt