Only the gprs_rlcmac_pdch will manipulate the paging list now. There
can be various more refactorings of the code but they can be done
later. E.g. on memory allocation failure we can continue instead
of leaving the code, we should also set any_tbf only after things
have been paged.
Rely on packet_paging_request returning NULL in case the queue
is empty. We should move the write_packet_paging_request into
a separate file/object as well.
When a PDCH is disabled all resources should be freed. This is
currently not possible as the PDCH does not know where it belongs
to. On top of that the list (and other resources) should be
properly initialized on construction so that disable() is idempotent
and does not check if it was disabled. During the re-factoring I
noticed that during a sysmobts re-start some resources are not
freed. I left a warning in the code to resolve this issue later.
Global state makes mocking/writing tests more difficult. Continue
by removing direct usage of the bts and adding it as pointer to
the function calls (showing the true dependencies of the functions)
Vladimir Rolbin pointed out that in case of the alloc_algorithm_a
the usf has not been assigned. For now move all the assignment into
a method and call it from the A and B algorithm.
This is the begin of a long march of turning tbf into a C++ class
and properly hiding the secrets inside this implementation instead
of having it spread across various different files.
Do not claim that the payload is not known. Add the missing break.
Do not print:
<0002> gprs_rlcmac.cpp:1174 GPRS_RLCMAC_CONTROL_BLOCK_OPT block payload is not supported.
<0002> gprs_rlcmac.cpp:1176 Unknown RLCMAC block payload.
For mocking/unit-testing/emulation (and a dual trx-systems) having
global state is quite bad. Cut back on the usage of the global
struct gprs_rlcmac_bts. It also makes the complexity of certain
routines more clear.
The timing advance of any TBF is stored when it ends. Whenever a new TBF
with the same TLLI is created (downlink TBF), the stored TA is recalled.
This algorithm assumes that the mobile does not move too fast during
transfer. Also the mobile must start a connection in order to get correct
initial timing advance.
This algorithm does not implement the timing advance procedure as defined
in TS 04.60. To implement the standard timing advance procedure, the BTS
must decode RACH on certain bursts, the mobile is expected to send them.
This requires much more complexity to a transceiver like USRP/UmTRX or
Calypso BTS.
The algorithm was tested at TA >= 8 and works quite well.
The measurements include:
- DL bandwidth usage
- DL packet loss rate
- DL measurements by mobile
- UL measurements by BTS
In order to receive DL measurements from mobile, it must be enabled via
system information message at BSC.
This simpliefies the allocation process.
tfi_alloc is responsible to allocate a TFI, not a time slot.
The first time slot available depends on multislot class and on other
ongoing TBF (concurrent TBFs), so it is part of the allocation
algorithm to select it.
The slots are choosen in a way that later selection of slots for
concurrent TBFs will have the same downlink/uplink control channel
(PACCH).
This is required for polling acknowledge of new TBF assignment on PACCH.
The MS will always have the same PACCH uplink slot while beeing in packet
transfer mode.
Original code: c7e7f6868b
(The code was committed earlier, but got lost somehow.)
I added IMSI, so the paging request is sent in correct paging group.
Also I excluded rest octets from pseudo length.
It is tested and it work.
Some MS will leave packet transfer mode, if TAI is given, but no timing
advance control messages are sent on PTCCH. This could results in
permanent loss of larger packets.
It is quite essential. It shows how TBFs are related and helps to estimate
states and timers (timeouts) of the MS.
In order to use it, it must be defined by a switch at gprs_rlcmac.h.
Be sure to use always two bytes of length information for DL-UNITDATA,
even if the length of LLC data is less than 128 bytes. This way the data
has always the same offset from a 32 bit boundary.
This is required, since we may change slot allocation. In case of a
change, we do not want to be unable to change, if the same TFI on one of
the other slots is already in use by a different TBF (having same TFI, but
on different slot).
It is mandatory to support it because MS may request a single block.
In this case the network must assign a single block.
It is possible to force single block allocation for all uplink requests
on RACH. (VTY option)
Holger Hans Peter Freyther