User Manual M900/M1800 Base Transceiver Station (BTS30) Table of Contents Table of Contents Chapter 5 F unctions and Performance ....................................................................................... 5-1 5.1 Ne tworking Function .......................................................................................................... 5-1 5.1.1 E1 Networking......................................................................................................... 5-1 5.1.2 SDH Ne tworking............................................................................................. ......... 5-3 5.1.3 Networking for Satellite Tra nsmission..................................................................... 5-4 5.2 Main RF Function ............................................................................................................... 5-6 5.3 Baseband Processin g ........................................................................................................ 5-8 5.3.1 Ch annel Types S upported ...................................................................................... 5-8 5.3.2 Chann el Combina tions Suppor ted .......................................................................... 5-9 5.4 Signaling Processing ......................................................................................................... 5-9 5.5 Ope ration and Main tenance ............................................................................................ 5-12 5.5.1 Software Loading .................................................................................................. 5-13 5.5.2 Abis Interface Manageme nt .................................................................................. 5-13 5.5.3 Air Interface Ma nagemen t ..................................................................................... 5-14 5.5.4 Testing Management ............................................................................................ 5-16 5.5.5 S tatus Ma nagemen t .............................................................................................. 5-16 5.5.6 Processing of Event Report s................................................................................. 5-17 5.5.7 Equip ment Man agement....................................................................................... 5-18 5.5.8 Site Configuration.................................................................................................. 5-20 5.5.9 Tracing Oper ations................................................................................................ 5-20 5.5.10 Other Functions................................................................................................... 5-21 5.6 System Indices............................ ..................................................................................... 5-21 5.7 Radio Interface Indices .................................................................................................... 5-23 5.7.1 Receivers .............................................................................................................. 5-23 5.7.2 Transmitter s .......................................................................................................... 5-26 Huawei Technologies Proprietary i
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User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
TRAU time adjustment
Satellite transmission delay affects the alignment of the TRAU frames. As the delay
in the common transmission modes is short, the TRAU frame adopts the simple
fixed cyclic frame alignment. While in satellite transmission, the CCU (channel coderunit) adopts the self-adaptive alignment, which ensures that data can be aligned in a
timely and correct manner in any delay amount, and that the transmission voice is of
high quality.
II. Solution to synchronization problems
The synchronization between BTS and BSC can be greatly affected by the
environmental factors which are stronger during satellite transmission, hence the
voice quality will also be affected.
To solve this problem, the clock source at the BTS side adopts clocks of high
accuracy and advanced APL algorithm. When BTS can synchronize with BSC, it will
work in the synchronous mode.
III. Solution to bit errors
Bit errors will affect system synchronization, voice quality, initiation of calls, call
connection and disconnection. So the reduction of bit errors must start with the
satellite equipment.
With measures implemented in both hardware and software design, Huawei'sE-Abis interface technology has greater error tolerance capability and demonstrates
excellent performance in error and jittery test, and in the actual running
environment.
5.2 Main RF Function
The BTS30 RF functions meet the GSM 05.05 specifications. It is characterized by
such advantages such as high sensitivity, flexible configuration, and convenient
operation and maintenance. A brief description of the main RF functions is given
below.
I. High receiving sensitivity
The receiving static sensitivity of the BTS30 is better than -109dBm (for 1800MHz),
and -110dBm (for 900MHz). High sensitivity ensures the high uplink performance of
the BS and it is also one of the preconditions for a better coverage of the BS.
User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
The Abis interface management covers two aspects: the connection management of
layer 1 and management of part of the signaling link layer. The Abis interface TS
switching equipment of the BTS30 fulfills the switching between the E1 line and HW
line inside the rack to accomplish the layer 1 connection of the link.
Signaling link connections should also be established on layer 2.
The Abis interface management has the following functions:
TEI set up (for both OML and RSL)
Signaling channel connection set up
Signaling channel disconnection
Traffic channel connection set up
Traffic channel disconnection
II. Transmission management
Transmission here refers to the cascade transmission of E1 signals. As both the
BTS30 E1 transmission and the Abis timeslot switching are carried out by BIU,
implementation of this function is similar to that of Abis interface management. Link
connection on layer 1 is set up by changing the timeslot switching configurations
between BIU and E1 lines.
One BSC normally can carry multiple SITEs. Between BSC and SITEs, multiple
connection modes are supported, such as star, chain, tree, ring and hybrid
networking. Except star networking, all other modes involve the cascademanagement of E1 signals, i.e., forwarding traffic and signaling to subsequent sites.
The ring connection mode also involves loop management.
Transmission management has the following functions:
Multi-point connection set up
Multi-point connection deletion
Ring connection set up
Ring connection deletion
5.5.3 Air Interface Management
The air interface management mainly involves the parameter configuration that
determine the physical channel and the logical channel of the air interface, including
the configuration of the attributes of the cell, carrier frequency and transmission
channels.
The physical channel parameters of the air interface mainly include the carrier and
the timeslot parameters, which are configured according to the carrier attributes.
Testing management is an important function of the base station maintenance. With
the help of this function, the user can determine and locate the fault in BTS. During
the normal operation of a base station, periodic tests should also be carried out over
certain items to trace the performance of the base stations and to predict the
possible faults of base stations.
It must be noted that with the increasing of base station maintenance functions,demands for testing functions become more stringent, which constitutes one of the
most extendable parts of operation and maintenance functions.
The BTS30 provides powerful testing functions with a large variety of test items
provided, mainly including:
1) TRX Abis link testing
2) Free burst testing
3) E1 self-loop testing
4) Functional object self-test, including:
Site self-test
Cell self-test
TRX self-test
Board self-test
5.5.5 Status Management
The status of various logical objects and physical objects of the base station is
stored in 3 entities, i.e., BSC, TMU, and boards. The correctness and consistency of
states stored in these 3 entities is one of the basic conditions for the normal
User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
The base station status management mainly involves 3 kinds of status:
management status, operation status, and availability status. Management status is
required to remain consistent from top to bottom, i.e., from BSC, TMU to boards,
while operation status is required to remain consistent from bottom to top. Availability status is the specific explanation of operation status.
Consistency of these 3 kinds of states is vitally important, for inconsistency will
result in resources waste as some available channels might not be distributed, or
abnormal service provision occurs due to possible distribution of damaged
channels.
TMU monitors the setup and disconnection of various communication links, and
checks the status of the boards in realtime. If any change occurs, it will immediately
report the change to BSC and MMI, and display it through the OMC.
5.5.6 Processing of Event Reports
Event report mainly refers to the report of internal base station errors, or fault reports
generated during alarming.
Considering the importance of such reports, it must be ensured that each command
and report reaches the destination and is correctly explained, i.e., there must be a
response mechanism. The response mechanism from top to bottom is stipulated in
GSM protocol 12.21, but the response mechanism from bottom to top is not yet
specified in the protocol. For the sake of simplicity and to save command codes, the
upward reports are directly returned as responses.
A base station can be managed through BSC and MMI. For inquiry operations, both
can perform the operations simultaneously. For operations that may change the
running status of the base station (e.g., parameters setting), only the one with the
management authority can perform such operations. By default, BSC enjoys the
management authority.
To obtain the management authority, MMI must first send to BSC a management
status changing request. After BSC confirms the request, it will issue a managementstatus changing command, so as to shift the management authority to MMI. When
MMI operation ends, it must request BSC to take back its management authority.
The BTS30 may involve two kinds of alarms: board alarms and environment alarms.
I. Board alarms When any board alarm occurs or disappears, the board reports it to TMU, and TMU
will report it to BSC or MMI immediately. According to the cause, an alarm may be
User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
Transmission and communication alarms: This mainly refers to an
out-of-synchronization alarm of either the local end or remote end of E1 port, or loop
interruption alarm.
Clock alarms: various kinds of clock source alarms and TBPU clock alarms.
Power supply alarm: over/under voltage alarms of power supply of the carrier part
and power supply fault alarms.
General alarms: hardware faults of various boards, internal bus alarms, and
software running errors.
After receiving alarm messages from a board, TMU will take the corresponding
measures according to the alarm severity. For a critical alarm, immediate measures
will be taken to reduce any possible damage, such as resetting the board or
switching off the carrier power supply, etc.
TMU reports all the alarms to BSC and MMI to display them at the graphic interface.
II. Environment alarms
Environment alarms (including fire, smog, intruder, water, temperature and humidity
etc.) are collected by the environment monitoring instrument. On receipt of an alarm,
TMU will activate the attached device(s) through the alarm box, such as
air-conditioner, fire-extinguisher, smoke-removing devices, and dehumidifier. Also, it
will report it to BSC and MMI for it to be displayed at the graphic interface.
5.5.7 Equipment Management
I. Equipment switchover
To guarantee the system reliability, the BTS30 provides active/standby configuration
for important components. In case of any abnormality in the active boards, the
system can shift the service to the standby boards automatically or manually.
In addition, the BSC can send a switchover command to perform switchover on theobject desired. When a board receives a switchover command from BSC, activated
by this command, it directly receives commands from the TMU to initiate switchover.
Otherwise, the switchover is initiated by the board itself, and will be directly reported
after the switchover.
II. Operation starting
The operation of the equipment involves the steps and synchronization during the
starting. The operation starting function is used to start the equipment at the proper
User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
III. Re-initialization
In some cases, the running object may require re-initialization, which is mostly
caused by the failure of the equipment or the need to reconfigure large quantity of
data. And it can be initiated by the command from BSC via TMU.
IV. Configuration of site output (external devices)
There may be some external devices for each BTS, such as air-conditioner,
dehumidifier, humidifier, and controllable camera etc. The controlling over these
devices can be regarded as output variables.
V. Power supply management commands
When some critical faults occur to carrier equipment, such as too high temperatureor standing wave ratio exceeding the threshold, make the equipment quit serving
any more or power off the carrier part (including the power amplifier) so as to
prevent it from being completely damaged. In case of mains power supply failure,
the base station can turn off some TRXs, and keep only the BCCH carrier working to
handle the necessary data so as to reduce the voice services and prolong the
service of standby power supply.
VI. Software and hardware version's query
During the maintenance, for example, when the software is being updated, usually
the software and hardware version number shall be checked. After TMU is started,
the software and hardware version number shall be read so as to upgrade the
database for future query, and to judge whether the version number is identical with
the configuration or not.
VII. Board re-initialization after resetting
After being reset, boards will request for re-initialization. The re-initialization process
is to configure the required parameters first, and then restart the board.
VIII. Processing of board and environment alarms
Base station alarms mainly includes two types: board alarms and environment
alarms. When there is any abnormality in board itself or its resources, a board
running failure alarm will be reported to TMU. Environment alarms are collected by
TMU and alarm box. TMU reports all alarm messages timely to BSC and take
User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance
5.5.8 Site Configuration
I. Configuration of logical parameters
The configuration of site logical parameters is to determine such basic site
configuration parameters as the number of sectors, baseband processing units and
carrier units etc. Logical units can be added or deleted during future network
expansion or network optimization.
II. Configuration of physical boards
Site physical board configuration is to configure, add or delete given boards for sites
in configuration tables.
5.5.9 Tracing Operations
I. Interface tracing
It is usually necessary to trace various interface messages during operation, for the
sake of convenient debugging, detecting and locating of faults occurred during
normal operation.
The interfaces now available for tracing include various interfaces between the TMU
layer 3 and its lower levels, and the air interface (Um interface). What's more, otherinterfaces can be added to the tracing list for the sake of convenient debugging.
II. Resource tracing
The resource utilization conditions are the important parameters for analyzing the
program efficiency and status, and important indexes for testing whether the system
meets the requirements or not. Resource tracing can be started or stopped
according to the actual need to adjust the traffic flow.
III. System logs
To keep system operation process records is one of the best way to trace the errors.
The TMU software log mainly keeps two types of information: one is the interface
message mentioned above, and the other is the program running errors. The board
log is reported to the TMU, from which it is transferred transparently to the BSC or