iBTS Overview
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iBTS description
 The term iBTS stands for e-mobility Internet BTS.
 The following types of iBTS are available:
• Indoor version (600 or 700)
• Outdoor version
 The main function of iBTS are:
• provide the means of communication between a UE and a network
 A Node B is a logical node responsible for radio transmission/reception in one or
more cells to/from the User Equipment.
 A Node B may consist of one or several iBTS ？
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Physical interfaces(1/2)
The NodeB provides 2 interfaces: Iub -> with the RNC
Uu -> with the mobile
The Iub interface consists of E1 Link connected to the CCM card.
 The Uu also called (air or radio interface) consists of RF ports
corresponding to main and diversity antenna(s) for one or several sectors.
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Physical interfaces(2/2)
 Several configurations are supported regarding the release and the number of
cards.
The current configuration in V1 is called STSR-1, which means Sectorized Transmitted,
Sectorized Received with 1 carrier frequency. For one sector only, we call it O1.
We use FDD (Frequency Division Duplex) mode,
i.e the uplink and downlink signals are not carried by the same frequency.
 The frequency range in FDD mode is :
• 2110-2170 MHz for Downlink
• 1920-1980 MHz for Uplink
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Outdoor & Indoor iBTS views
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iBTS Cards
C
C
E
E
M
M
5
4
1
2
T T C
R R C
M M M
1 2 1
R
E
C C C C T
S
E E E E E R
R
M M M M M
V
E 1 2 3 6 3
D
F
G
P
S
A
M
P
A
1
I
L
L
F
F
P
I
P
I
A
L
A
L
3
L
5
L
E
E
E
R
R
R
3 4 5 6 7 8 9 10 11 12
DDM 1
DDM 2
DDM 3
Configuration for V1.1
Additionnal cards for inventory purposes (V1.2 and higher)
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Configuration Evolution (1/2)
V1.1
V1.2
1 CCM, 1 CEM, 1 TRM
1 carrier
1 to 3 PAs
no Tx diversity
1 to 3 DDMs
no redundancy
Configurations supported:
O1, STSR1
1 CCM, 1 to 2 CEMs
1 carrier
Configurations supported:
1 to 2 TRMs
no Tx diversity
O1, STSR1
1 to 3 PAs
no redundancy
1 to 3 DDMs
1 CCM, 1 to 2 CEMs
V2
1 to 2 TRMs
Multi carriers (up to 2)
1 to 3 PAs
no Tx diversity
1 to 3 DDMs
no redundancy
Configurations supported:
O1, OTSR1, OTBR1,O2,STSR2
1 Tx Splitter
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Configuration Evolution (2/2)
2A
4A
6A
TRM
PA
DDM
Tx
Splitter
Nb Cells
Carrier/
Cell
Nb
Carriers
O1
1
1
1
0
1
1
1
O1-D
1
2
1
0
1
1
1
O2
2
1
1
0
1
2
2
OTSR1
1
1
2
1
1
1
1
STSR1
1
2
2
0
2
1
2
STSR1-D
1
4
2
0
2
1
2
STSR2
2
2
2
0
2
2
4
STSR3
3
2
2
0
2
3
6
OTSR1
1
1
3
1
1
1
1
STSR1
1
3
3
0
3
1
3
STSR1-D
1
6
3
0
3
1
3
STSR2
2
3
3
0
3
2
6
STSR2-D
2
6
3
0
3
2
6
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DIGITAL SHELF(1/4)
CCM (Core Control Module)
 Functions:
• Iub interface
• Call Processing
• Data switching and routing
• OAM Management
• iBTS frequency and timing reference
Serial port
Ethernet port
 The CCM consists of 3 boards
E1 links
• BRIC
• AXE
• CCMIC
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DIGITAL SHELF(2/4)
CEM (Channel Element Module)
 Function:
• digital signal processing for both Tx and Rx paths.
 The functionnal block of the CEM can be divided into 2 units:
• The BBU (Base Band Unit) function
• The ICU (Interface and Control Unit) function
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DIGITAL SHELF(3/4)
TRM (Transceiver Receiver Module)
 Functions:
Towards the PAs
• modulation & demodulation
• digital-analog & analog-digital conversion
Downlink Path
• up and down frequency conversion
 The TRM consists of 2 boards:
• 1 dTRM board
• 1 rTRM board
To the Interco
From the DDMs
Uplink Path
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DIGITAL SHELF(4/4)
GPSAM (GPS & Alarm Module)
Towards the
Dallas
modules
 Functions:
• collection of the alarms, inventory and commissioning
information
• supply of timing information
 The GPSAM is connected to the CCM through the backplane
 The GPSAM has no debug port.
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RF Block(1/2)
PA (Power Amplifier)
From the TRM
 Functions:
• downlink signal amplification
 The MCPA is connected to the antenna through the DDM
 It can handle up to 4 carriers.
Towards the DDM
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RF Block(2/2)
DDM (Dual Duplexer Module)
 Functions:
• separate the downlink and uplink paths
• low noise amplifier
From the PAs
To the antennas
Uplink path
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Data architecture(1/2)
 The CCM, CEM and TRM cards contain FFS (Flash File System)
in which data are stored.
CCM
CEM
TRM
/ffs0 -> Software version N
/ffs0
/ffs0
/ffs1 -> Software version N+1
/ffs1
/ffs1
/data ->info. about the
software versions
/data ->info. about the
software versions
/ram
/ram
/ffs2 -> for GSM only
/data -> info. put
after the reboot
/ram
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Data architecture(2/2)
• These ffs can be seen as directories, mounted at each reboot.
• There is only one active ffs at a given time.
• It is forbidden to write or delete files in the active ffs.
• The ffs are accessible through a ftp session.
 Information about card types and software references are stored in the
MIM (Memory Information Module) of each digital card.
 The MIM is accessible through a telnet session.
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TIL (Terminal d’ Installation Locale)
 The TIL is a tool used to configure some parameters inside the iBTS.
 It consists of 2 elements:
• a TIL Server present on the CCM card
• a TIL Applet downloadable on a PC from the CCM
 Using the TIL, you can:
• download new software,
• display the current alarms,
• display the BISTS results,
• display and change I&C parameters.
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Connecting to the iBTS with TIL
A laptop with:
 The TIL is used locally on
•A browser(IE or
Netscape)
site for first commissioning.
•Java 1.3.0 plugin
Direct Connection through
a crossed cable on the
Ethernet port of the CCM
(2nd one)
CCM
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I&C Parameters(1/3)
 The I&C (Installation & Commissioning) parameters need to be set once, with the
TIL, after the iBTS is installed.
They consist, among other things, in OAM parameters such as:
•Vcc for the OAM path
•IP/ATM address for the iBTS,
•IP address for the Main Server
•…
 The OAM parameters are used to establish a remote connection to the iBTS from
an OMC-B and thus performing operations such as: Open Link, Software
Downloading and Build.
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I&C Parameters(2/3)
Some of I&C parameters can be
displayed
and changed using the TIL:
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I&C Parameters(3/3)
The I&C parameters are stored in 3 Memory modules (type Dallas DS2433) called SIM,
IC1 and IC2.
 The content of these modules is retrieved by the GPSAM card and sent to the CCM at
each reboot.
 The SIM contains manufactury information.
 The IC1 contains the commissioning parameters.
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Connecting to the iBTS with OMC-B
OAM
Main Server
Once the I&C parameters are correctly set inside the BTS,
the latter sends a request to the OMC-B in order to establish
a connection. If the OMC-B responds to this request, the link
LAN
is said to be open.
The OMC-B can then retrieve the alarms from the iBTS
and perform management operations.
Remote Connection
through E1 link
CCM
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OAM & Data Paths
CN
Access Node
(AN)
Towards the Core
Network
E1 link
IN
Optical Fiber
Ethernet link
iBTS
E1 link
LAN
Signalling & Data Path
OAM Path
Main Server
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iBTS Upgrade
 The Upgrade can be done using the Upgrade Manager,
if the iBTS is connected to the OMC-B.
 If not, it is also possible to use the TIL on a laptop directly connected to the CCM card.
 The software is downloaded into the CCM card and then, distributed to the other cards
of the iBTS through HSSL (High Speed Serial Links) on the backplane.
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BTS Build(1/3)
 The Build is an operation performed from the OMC-B and intended for giving
the iBTS the parameters needed to communicate with the RNC.
 The result of the Build is a file named DLU.TXT. It is downloaded to the iBTS
and contains:
• The VC for AAL5 and AAL2
• The ATM profiles
• The BTS serialisation number
•…
 Despite its extension, the DLU.TXT file is in binary format and can not be
read directly with a text editor.
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BTS Build(2/3)
3
steps:
1 The OMC-B checks the software version present in the passive ffs.
If it is not the same as the one present in the active ffs, the files are copied
from active ffs into passive ffs.
Active ffs
Passive ffs
Version X
Version Y
If Version X
Version X
Version Y
Version X
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BTS Build(3/3)
2 The OMC-B downloads the DLU file inside the passive ffs.
3 The passive ffs is activated and the BTS restarts.
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Cell Setup (1/2)
 Once the iBTS is built:
iBTS
RNC
SSCOP link
NBAP:NodeB restart indication
NBAP:NodeB resource notification
NBAP:Cell Setup Request
NBAP:Cell Setup Response
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Cell Setup (2/2)
iBTS
RNC
NBAP:CTCH Setup Request (FACH)
NBAP:CTCH Setup Response (FACH)
NBAP:CTCH Setup Request (RACH)
NBAP:CTCH Setup Response (RACH)
NBAP:SysInfo Update Request
NBAP:SysInfo Update Response
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