According to 3GPP TS 05.02, section 6.4.1, CBCH replaces
SDCCH number 2 in both V (BCCH+CCCH+SDCCH/4+SACCH/4) and
VII (SDCCH/8+SACCH/8) logical channel combinations.
Unfortunately it is not clear whether we can use stolen UL slots
for RACH or not. For now, we should mark all of them as IDLE.
Somehow TRXC_SDCCH4_2 slots were left in the definition of
combination V (combined CCCH+BCCH). This is not critical,
but may be looking confusing. Let's fix this.
Change-Id: Id30f2fac3274de3edff4ae59f77d9c9cf8059155
Having magic pre-calculated hex-masks gives one quite high chances
to shoot oneself in the foot, and decreases readability in general.
Let's do this pre-calculation during the compilation process, so
it's much easier to read, extend and spot potential bugs.
Change-Id: If945b3654e35c83fc0220fdd6d99c1c7a0503386
According to GSM TS 05.02, section 3.3.5, Cell Broadcast Channel
(CBCH) is a downlink only channel, which is used to carry the
short message service cell broadcast (SMSCB). CBCH is optional,
and uses the same physical channel as SDCCH. More precisely,
CBCH replaces sub-slot number 2 of SDCCH channels when enabled.
This change introduces the CBCH enabled multi-frame layouts,
and two separate logical channel types:
- GSM_PCHAN_CCCH_SDCCH4_CBCH (lchan TRXC_SDCCH4_CBCH),
- GSM_PCHAN_SDCCH8_SACCH8C_CBCH (lchan TRXC_SDCCH8_CBCH).
Both logical channels are separately identified using
the following Osmocom specific cbits:
- TRXC_SDCCH4_CBCH - 0x18 (0b11000),
- TRXC_SDCCH8_CBCH - 0x19 (0b11001).
The reason of this separation is that we somehow need to
distinguish between CBCH on C0/TS0, and CBCH on CX/TS0.
Unlike TRXC_SDCCH8_CBCH, TRXC_SDCCH4_CBCH is enabled
automatically (TRX_CH_FLAG_AUTO), so CBCH messages
can be decoded on C0 while being in idle mode.
Change-Id: Iad9905fc3a8a012ff1ada26ff95af384816f9873
Vadim Yanitskiy
Harald Welte