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doc: bts-examples: discuss Ericsson RBS EGPRS configuration 

Add a configuration file example to illustrate how exactly EGPRS is
configured on ericsson RBS BTSs.

Related: OS#5198
Change-Id: I2fb5b4d9300b16b0fac48f33b5db81442ab25031
changes/32/32032/3
Philipp Maier 2023-03-23 17:26:33 +01:00
parent f99952c2b0
commit 2365db4856
2 changed files with 135 additions and 1 deletions
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134
doc/manuals/chapters/bts-examples.adoc
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@ -175,6 +175,7 @@ For building a multi-TRX setup, you also need to connect the TIB cables
between the two nanoBTS units, as well as the coaxial/RF AUX cabling.
====
[[example_e1_cfg]]
=== Example configuration for OsmoBSC with E1 BTS
The following configuration sample illustrates the usage of BTSs that are
@ -273,6 +274,139 @@ network
<9> The bandwidth of one E1 timeslot matches the bandwidth of 4 GSM air interface timeslots. The E1 timeslot is split up into four sub-slots, which are then assigned to one GSM air interface timeslot each. Since the first timeslot on the first TRX is already used for signaling we begin the sub-slot counting with sub-slot 1 for alignment reasons.
=== Example configuration for OsmoBSC with Ericsson RBS E1 BTS and EGPRS
The following example illustrates the usage of Ericsson RBS2000/RBS6000 BTSs.
This classic E1 BTS has no built in PCU and therefore requires the configuration
of a BSC co-located OsmoPCU (see also: <<cfg_bsc_co_located_pcu>>).
It should also be noted that the Ericsson RBS2000/RBS6000 series is the first
BTS of this type to be supported by OsmoBTS and OsmoPCU. The implementation has
been made possible through funding by the NLnet Foundation.
Ericsson RBS2000/RBS6000 BTSs feature two GPRS modes. A 16kbps GPRS mode where
only CS1 and CS2 are supported and an EGPRS mode where MCS1 to MCS9 are
supported. OsmoPCU offers support for both modes but since the 16kbps mode only
supports classic GPRS with CS1 and CS2 it is more of experimental interest
and shall not be discussed further. The following example will describe how
to configure the 64kbps mode with EGPRS.
In the following example we also expect that the user is already familliar
with the E1 configuration example above (see also: <<example_e1_cfg>>)
.OsmoBSC configured for single-TRX E1 Ericsson DUG20 with EGPRS
====
----
e1_input
e1_line 0 driver dahdi
e1_line 0 port 3
network
network country code 1
mobile network code 1
encryption a5 0
neci 1
handover 0
pcu-socket /tmp/pcu_bts <1>
bts 0
type rbs2000
band GSM900
om2000 version-limit oml gen 12 rev 10
cell_identity 0
location_area_code 0x0001
training_sequence_code 7
base_station_id_code 63
ms max power 15
cell reselection hysteresis 4
rxlev access min 0
channel allocator mode set-all ascending
rach tx integer 9
rach max transmission 7
oml e1 line 0 timeslot 1 sub-slot full
oml e1 tei 62
gprs mode egprs <2>
gprs routing area 0
gprs network-control-order nc0
gprs cell bvci 2
gprs nsei 101
gprs nsvc 0 nsvci 101
gprs nsvc 0 local udp port 23100
gprs nsvc 0 remote udp port 23000
gprs nsvc 0 remote ip 127.0.0.1
gprs nsvc 1 nsvci 0
gprs nsvc 1 local udp port 0
gprs nsvc 1 remote udp port 0
gprs nsvc 1 remote ip 0.0.0.0
is-connection-list add 4 712 36 <3>
trx 0
rf_locked 0
arfcn 123
nominal power 42
max_power_red 12
rsl e1 line 0 timeslot 1 sub-slot full
rsl e1 tei 0
timeslot 0
phys_chan_config CCCH+SDCCH4
hopping enabled 0
e1 line 0 timeslot 1 sub-slot full
timeslot 1
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 3 sub-slot full <4>
timeslot 2
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 4 sub-slot full
timeslot 3
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 5 sub-slot full
timeslot 4
phys_chan_config TCH/F_TCH/H_SDCCH8_PDCH <5>
hopping enabled 0
e1 line 0 timeslot 6 sub-slot full
timeslot 5
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 7 sub-slot full
timeslot 6
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 8 sub-slot full
timeslot 7
phys_chan_config TCH/F
hopping enabled 0
e1 line 0 timeslot 9 sub-slot full
----
====
<1> This configures the PCU socket path (see also: <<cfg_bsc_co_located_pcu>>)
<2> This configures the general GPRS parameters. The configuration is no
different from BTS with built-in PCU.
<3> The Ericsson RBS2000/RBS6000 series has an built in “Interface Switch” (IS)
that offers flexible way to reconfigure the interconnection between the internal
components of the BTS and the external E1 line. Since 16kbps subslots cannot
supply the bandwidth required for EGPRS the IS must be configured to connect
the 64kbps interface of the TRU to the external E1 line. For a more detailed
description of the IS see <<cfg_ericsson_rbs_is>>.
<4> Since we are using the 64kbps TRU interface we must configure a full E1
timeslot per air interface time slot. For Speech this will have no effect on
the TRAU frame format. The only difference is that always the first 16kbps
subslot of the assigned E1 timeslot is used. OsmoMGW will be instructed
accordingly by OsmoBSC, so no re-configuration of OsmoMGW is required.
<5> In this example we will use air interface TS 4 as PDCH. As mentioned
earlier Ericsson RBS2000/RBS6000 supports the 'DYNAMIC/OSMOCOM' timeslot model.
PDCH timeslots must be configured as dynamic timeslots. It is not possible to
configure static PDCHs. Therefore the phys_chan_config must be set to
TCH/F_TCH/H_SDCCH8_PDCH in order to use the air interface timeslot as PDCH.
NOTE: As of March 2023 the BSC co-located PCU support for Ericsson RBS was
tested only with a single BTS. Even though OsmoBSC and OsmoPCU should be able
to handle multiple BTS, unexpected bahviour should be taken into account.
=== E1 Line number and MGCP trunk number
The switching of the voice channels is done via OsmoMGW, which acts as a media
converter between E1 and VoIP (RTP). OsmoBSC will use the E1 line number to

2
doc/manuals/chapters/running.adoc
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@ -219,7 +219,7 @@ smlc
More detailed configuration is described in <<smlc-config>>.
[[cfg_bsc_co_located_pcu]]
==== Configure BSC co-located PCU
While small IP based BTSs usually come with a built in PCU (BTS co-located