05-Functions and Performance

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User ManualM900/M1800 Base Transceiver Station (BTS30) Table of Contents

Table of Contents

Chapter 5 Functions and Performance ....................................................................................... 5-1

5.1 Networking Function.......................................................................................................... 5-1

5.1.1 E1 Networking......................................................................................................... 5-1

5.1.2 SDH Networking...................................................................................................... 5-3

5.1.3 Networking for Satellite Transmission..................................................................... 5-4

5.2 Main RF Function............................................................................................................... 5-6

5.3 Baseband Processing........................................................................................................ 5-8

5.3.1 Channel Types Supported ...................................................................................... 5-8

5.3.2 Channel Combinations Supported .......................................................................... 5-9

5.4 Signaling Processing ......................................................................................................... 5-9

5.5 Operation and Maintenance ............................................................................................5-12

5.5.1 Software Loading .................................................................................................. 5-13

5.5.2 Abis Interface Management .................................................................................. 5-13

5.5.3 Air Interface Management..................................................................................... 5-14

5.5.4 Testing Management ............................................................................................5-16

5.5.5 Status Management .............................................................................................. 5-16

5.5.6 Processing of Event Reports................................................................................. 5-17

5.5.7 Equipment Management....................................................................................... 5-18 5.5.8 Site Configuration.................................................................................................. 5-20

5.5.9 Tracing Operations................................................................................................ 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 Transmitters .......................................................................................................... 5-26

Huawei Technologies Proprietary

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User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 5 Functions and Performance

Chapter 5 Functions and Performance

The main functions of BTS30 will be introduced in the aspects listed: networking

function, baseband processing, signaling processing and operation and

maintenance.

5.1 Networking Function

The BTS30 allows for a flexible networking modes with many built-in transmission

functions. It supports transmission modes such as E1, SDH.

5.1.1 E1 Networking

With one site as a basic unit, M900/M1800 BTS30 supports star, tree, chain and ring

E1 networking topologies, which are illustrated in Figure 5-1.

BSC

BTS0

BTS1

BTS2

BSC BTS0

BTS1

BTS2

BTS3

BSC BTS0 BTS1 BSC BTS0 BTS1

star networking tree networking

ring networkingchain networking

Figure 5-1 The BTS30 E1 networking mode

Each TMU board provides 4 E1 interfaces and each cabinet can be configured with

2 TMU boards. If one interface is connected to the superior network, a maximum of

7 tributaries can be provided. A comparison between various connection modes is

made in the following.


5-1




I. Star networking

Each site is connected directly to BSC by an E1 link, which brings very convenient

maintenance and simple network construction.

Signals pass through very few nodes, which means that no BTS depends on one

another. So in the case of the failure of one BTS, other BTSs will not be affected.

This networking mode is usually applied in densely populated urban areas to

facilitate easy expansion. But this type of networking requires a relatively large

number of transmission links.

II. Tree networking

Tree networking has a complicated network structure. Signals pass through many

nodes, i.e. any abnormality in the superior site will affect the subordinate sites,

which leads to low line reliability.

This type of networking is applicable in vast sparely-populated areas density. But in

such configuration, further expansion is quite difficult because it requires

reconstructing of the network.

Since a BTS usually chooses the phase locking mode for the clock of its superior

network and each time of choosing the phase locking will lead to the degeneration

of clock quality, the number of BSC signals pass through should be restricted (the

number of recommended serial connection layers is not more than five, i.e. thedepth of the tree should not exceed five layers).

III. Chain networking

Along highways and railway tracks where the population density is very low, the

most suitable networking is chain topology. But the problem lies in that in chain

networking the signals pass through many nodes, resulting in poor link reliability. But

for these areas, it has considerable advantages. It saves large quantity of

transmission equipment.

Similar to the tree networking, the number of serial connection layers should be

restricted and the number of the nodes that signals pass through should not exceed

5.

IV. Ring networking

Normally, the ring network is recommended because of its strong self-healing ability.

If the optical fiber in a certain area is damaged, the ring network can be self healed

into a chain network, without affecting services in any sense. The ring networking of

BTS30 should be supported by ABA and ABB.


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In practice a cellular network can have one or more than one network topology

according to the actual physical and geographical requirements. So, considerable

amount of transmission equipment investment can be saved and service quality can

be ensured if the networking modes are applied correctly.

5.1.2 SDH Networking

The BTS30 supports built-in transmission equipment. The ASU boards developed by

Huawei are inserted in the common resource frame of the BTS30. The E1 on the

BSC side can access the SDH network via Huawei’s OptiX155A transmission

equipment.

Huawei's transmission equipment is adaptable to complex network structures under

the support of its powerful cross-connect capability, abundant flexible interfaces, andadvanced software functions.

As alternative optical transmission equipment of an extremely high performance/

price ratio in OptiX155/622A networking, ASU in actual networking can interwork

with OptiX155/622A/B or Huawei's standard transmission equipment via the STM-1

optical interface. Besides, according to the transmission networking mode, it can

form both ring and chain topologies.

A chain or ring network topology can be implemented depending on the distribution

of the network routes. Normally, the ring network (as shown in Figure 5-2) is

recommended because of its strong self-healing ability. If the optical fiber in a

certain area is damaged, the ring network can be self healed into a chain network,

without affecting services in any sense.

Normally in areas along railways and highways, chain networking is the most

suitable solution (as shown in Figure 5-3). But even in such cases, if the distance

between the stations is not too far (usually, the maximum distance between 3

stations 80km), and there are enough optical fibers (4 fibers), ring networking is still

recommended.


5-3




TMU

ASU

ASU

ASU TMU

TMU

155ABSC

BTS0

BTS2

BTS1

E1

E1

E1

E1

Optical fiber

Optical fiber Optical fiber

Optical fiber

Figure 5-2 SDH ring networking

BSC 155A ASU

TMU

ASU

TMU

BTS0 BTS1

E1E1

E1Optical

fiber

Opticalfiber

Figure 5-3 SDH chain networking

5.1.3 Networking for Satellite Transmission

In sparsely populated areas with poor transportation conditions, it is very hard and

expensive to deploy land transmission network since common transmission

technology and common BTS can hardly meet the requirements in such areas. So in

these areas, satellite transmission is really a cost-effective and efficient solution.

Figure 5-4 shows the networking for satellite transmission.


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SDH/PDH

or microwave/cable

E1

E1

MSCGround station

BTS

BTS

BTS

BTS

Ground receivestation

Ground receivestation

BSC

Figure 5-4 Networking for satellite transmission

Networking for satellite transmission is now faced with technological difficulties,

which is much related to some inherent features of satellite transmission, such as

long transmission delay and poor stability of transmission links. These difficulties

greatly constrains the promotion and application of satellite networking. To

overcome these problems, Huawei offers an effective and complete solution as

described in the following.

I. Solution to long transmission delay

Transmission delay at the Abis interface

During satellite transmission, there is a fixed delay of hundreds of milliseconds

during the signaling control process on the Abis interface. To avoid timeout release

of the activated call due to transmission delay, multiple timers are used for the

signaling between BTS and BSC.

Handover

Due to the delay, the handover command issued from the BSC arrives at the BTS in

hundreds of milliseconds, which leads to the degeneration of the voice quality of the

mobile phone during this period. But in M900/M1800 BTS30, the functions of

filtering, interleaving, PN judgement and prediction of the measurement report can

be adjusted by setting parameters, and a special handover algorithm can be used to

eliminate the impact of time delay.


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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.


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II. Flexible configuration

The BTS30 can support 1~18 TRXs in each sector. The omni or sector cell (over 3

sectors) can be configured according to specific circumstances or the requirements

of the operator. By adjusting the front end gain (such as the tower-top amplifier and

the low noise amplifier), a BTS can also compensate the loss of feeders of different

lengths, thus ensures the consistency in system receiving gain.

III. Convenient operation and maintenance

The RF unit of the BTS30 can be remotely controlled by the OMC to change

transmitting power and transmitting frequencies. Alarm signals generated at the RF

unit are reported to the OMC, so the operating personnel can observe and control

the operation of the RF unit.

IV. Diversity receiving

The BTS30 provides diversity receiving function that is implemented by two

independent receiving equipment, including antennas, tower top amplifier (optional),

feeders, dividers, and receivers.

Both receivers demodulate received signals, which are then sent to the baseband

processing unit for decoding by diversity algorithm. This diversity receiving function

can provide 3~5dB diversity gain.

The application of diversity receiving technology enhances the anti-fading abilities of

the base station receivers, so that the base station can maintain a good receiving

performance even in complex radio environments.

V. RF Hopping

Hopping is another important tool to enhance the performance of the base station. It

enhances not only the anti-fading ability of uplinks and downlinks, but also the

security of communication.

The BTS30 supports both frequency hopping and non-frequency hopping modes.

When frequency hopping is required, the transceiver controlled by BSC can change

its carrier frequency according to a hopping sequence which can be set through

OMC. In non-hopping mode, the transceiver is locked at a certain frequency.

The frequency hopping of the BTS30 is realized through the real-time switchover

between two frequency synthesizers. This implementation mode has two

advantages, one is that the requirement about the rate of the frequency synthesizer

can be reduced, the other is that one of the two frequency synthesizers can function

as a backup to enhance the system reliability in non-frequency hopping mode.


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Besides the traditional frame hopping, the BTS30 supports timeslot (TS) hopping,

which further enhances the anti-fading ability.

VI. Power control

The BTS30 provides both static and dynamic power controls.

Static power control is used to adjust the service coverage range of BTS, i.e. it

defines the coverage area of the cell. It has 0~10 power levels in step of 2dB.

When a mobile station moves and the distance to BTS changes, BSC can adjust

BTS transmitting power according to the distances automatically. This process is

called dynamic power control. It has 0~15 different power levels in steps of 2dB.

The power control at each level adopts automatic power closed-loop control (APC),

which ensures a minimum power deviation.

When a timeslot is idle, as there are no downlink signals, BSC will send a command

to BTS to shut down the transmitting power of this timeslot.

These power control functions can enhance the efficiency of transmitters, the

reliability of power amplifier, and can also cut the interference of transmitters to the

minimum.

5.3 Baseband Processing

The baseband processing unit mainly fulfills the functions of the physical layer on

the Um interface, and processes all the full-duplex channel baseband data on a

TDMA frame.

At the transmitting end, it performs rate adaptation, channel encoding and

interleaving, encryption, and the generation of TDMA bursts. At the receiving end, it

is responsible for digital demodulation, decryption, de-interleaving, channel

decoding and rate adaptation.

5.3.1 Channel Types Supported

The baseband processing unit supports the following channel types:

TCH/EFS: Enhanced Full-rate Speech Traffic Channel

TCH/FS: Full-rate Speech Traffic Channel

TCH/F9.6: Full-rate Data Traffic Channel (9.6kbits)

TCH/F4.8: Full-rate Data Traffic Channel (4.8kbit/s)

TCH/F2.4: Full-rate Data Traffic Channel ( 2.4kbit/s)

FCCH: Frequency-Correction Channel

SCH: Synchronization Channel


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BCCH: Broadcast Control Channel

PCH: Paging Channel

RACH: Random Access Channel

AGCH: Access Grant Channel SDCCH/8: Standalone Dedicated Control Channel

SACCH/C8: Slow Associated Control Channel/SDCCH/8

SACCH/TF: Slow Associated Control Channel/TCH/F

FACCH/F: Fast Associated Control Channel/Full Rate

SDCCH/4: Standalone Dedicated Control Channel/BCCH/CCCH

SACCH/C4: Slow Associated Control Channel/SDCCH/4

CBCH: Cell Broadcast Channel

5.3.2 Channel Combinations Supported

The baseband processing unit supports the following types of channel

combinations:

TCH/F+FACCH/F+SACCH/TF

FCCH+SCH+BCCH+CCCH

FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/C4

BCCH+CCCH

SDCCH/8+SACCH/8

SDCCH/8+SACCH/8+CBCH

FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/C4+CBCH Here CCCH=PCH+RACH+AGCH

5.4 Signaling Processing

The BTS30 signaling processing mainly fulfills:

The interworking between MS and BSS/NSS on the Um interface.

Management function of the radio resources under the control of the BSC.

The BTS30 signaling processing includes radio link management, dedicated

channel management, common channel management and TRX management.

I. Radio link layer management procedures

Link establishment indication procedure: Through this procedure BTS indicates

to the BSC that a multiframe data link has been established at the initiative of an MS.

BSC can use this indication to set up an SCCP connection to MSC.

Link establishment request procedure: Through this procedure BSC request the

setup of a multiframe data link on the radio channel.


5-9




Link release indication procedure: Through this procedure BTS indicates to BSC

that a radio link has been released at the initiative of an MS.

Link release request procedure: Through this procedure BSC requests the BTS to

release a radio link.

Transfer procedure of a transparent L3-message in acknowledged mode:

Through this procedure BSC requests the BTS to send a transparent Um interface

RIL3 message in acknowledged mode.

Receive procedure of a transparent L3-message in acknowledged mode:

Through this procedure BTS indicates the BSC to receive a transparent Um

interface RIL3 message in acknowledged mode.

Transfer procedure of a transparent L3-message in unacknowledged mode:

Through this procedure BSC requests the BTS to send a transparent Um interface

RIL3 message in non-acknowledged mode.

Receive procedure of a transparent L3-message in unacknowledged mode:

Through this procedure BTS indicates the BSC to receive a transparent Um

interface RIL3 message in non-acknowledged mode.

Link error indication procedure: Through this procedure BTS indicates BSC

incase of any abnormality in the radio link layer.

II. Dedicated channel management procedures

Channel activation procedure: Through which the BSC sends commands to BTS

to activate a dedicated channel for a certain MS. After the activation, BSC assigns

the channel to the MS through commands such as Immediate Assign, Assign

Command, Additional Assignment or Handover commands.

Channel mode modify procedure: This procedure is used by BSC to request BTS

to change the mode of the activated channel.

Handover detection procedure: This procedure is used between the target BTS

and target BSC to detect the handover access of MS.

Start ciphering procedure: Used for starting the ciphering procedure defined in TS

GSM 04.08.

Measurement reporting procedure: It includes the necessary basic measurement

reporting procedure and optional measurement reporting procedure with

preprocessing. BTS reports all parameters related to handover decision to the BSC

through it.


5-10




SACCH deactivation procedure: According to the requirements of channel release

procedure specified in TS GSM 04.08, BSC uses this procedure to deactivate TRX

related SACCH channel.

Radio channel release procedure: BSC uses this procedure to instruct BTS to

release a radio channel, which is not in use state.

MS power control procedure: BSS uses this procedure to control the transmitting

power of the MS related to a specific activated channel. MS power control decision

must be implemented in BSC, and as an optional procedure in BTS.

Base station transmission power control procedure: BSS uses this procedure to

control the transmission power of the activated channel in TRX. The base station

transmitting power control decision should be implemented in BSC, or in BTS.

Connection failure procedure: BTS uses this procedure to indicate to BSC that an

activated dedicated channel is already disconnected.

Physical environment content request procedure: BSC uses this procedure to

obtain the physical parameters of a specific channel. This usually occurs before a

channel change. This is an optional procedure.

SACCH information change procedure: BSC uses this procedure to instruct BTS

to change the information (system information) filled in a specific SACCH channel.

III. Common channel management procedures

MS channel request procedure: This procedure is triggered when TRX detects

random access ("channel request" message) from the mobile station.

Paging procedure: It is used to page information on a specific paging sub-channel.

It is initiated by MSC and paged through BSC. BSC determines the paging group to

be used according to the IMSI of the called MS. The value of this paging group

together with the identity of the mobile station is sent to BTS.

Immediate assignment procedure: When a mobile station accesses BTS, BSC

uses this procedure to assign a dedicated channel for the mobile stationimmediately.

Deletion indication procedure: BTS uses this procedure to indicate to BSC that a

RIL3-RR immediate assignment message is deleted (i.e., not put in the AGCH array)

due to overloading of the AGCH channel.

CCCH load indication procedure: BTS uses this procedure to indicate to BSC the

load on a specific CCCH channel.

Broadcast information change procedure: BSC uses this procedure to instruct

the BTS to broadcast new system messages on the BCCH channel.


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Short message cell broadcast procedure: BSC uses this procedure to request

BTS to issue cell broadcast short messages.

IV. TRX management procedures

SACCH filling information change procedure: BSC uses this procedure to

indicate BTS to use new system information on all downlink SACCH channels.

Radio resources indication procedure: BTS uses this procedure to indicate the

interference level on each idle dedicated channel of TRX to BSC.

Traffic control procedure: FUC uses this procedure to indicate the overload

condition of TRX to BSC, the cause may be CCCH overload, ACCH overload or

processor overload.

Error reporting procedure: BTS uses this procedure to report the BSC about

detected downlink message errors that can not be reported by other protocols.

5.5 Operation and Maintenance The BTS30 also provides powerful operation and maintenance functions. It has four

major functional modules, including the software loading, the configuration of object

attributes of the base station, the equipment management and the operational status

monitoring.

Software loading: BSC stores copies of software of all BTS boards. So when BTS

operates for the first time after the installation, BTS successfully resets or BTS

software is upgraded, the BSC will performs software loading to BTS.

Configuration management: including attributes configuration of such managed

objects as sites, cells, radio carriers, and channels, as well as the management of

Abis interface and transmission equipment.

Equipment management: including the detection of equipment switchover,

resetting, and faults, performance testing, statistics measurement and status event

reporting.

Running status monitoring: including the monitoring and recording of various

message flows, status conversion processes, and change of environment

parameters during the operation of the base stations.


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5.5.1 Software Loading

I. TMU software loading

After the power on or manual/auto restart of the TMU, it will request the BSC for the

software version confirmation to ensure that the version acknowledged by the BSC

is in operation. If the version number is incorrect, the BSC will load the correct

version to the TMU.

All software loaded from the BSC to the TMU is stored in the Flash RAM of the TMU.

When the BSC requests the activation, the TMU will execute the operation of the

new software version.

II. Software loading from TMU to boards

After the manual/auto resetting, the board will send the software version

confirmation request to TMU. TMU checks whether its version number is identical to

that stored in the FLASH MEMORY. If it is, TMU will directly activate the version of

this software. If it is not, TMU will load the version previously saved to the board, so

as to ensure that the proper version is loaded and operating in this board. In

addition, the BSC can also update the software version of the board through TMU.

The validity of the software is of great importance, therefore, both layer 2 and layer 3

have the checking and reloading system to guarantee high reliability.

III. Centralized management of software versions

To facilitate software updating, this function is provided to load software from BSC or

MMI to the boards of BTS. As mentioned before, this function is implemented

through the TMU. A TMU stores two versions of the software for the boards TMU,

TBU (including SCP, CHDSP and EQDSP) and STU (including SCP and DSP), etc.,

and their version number is recorded respectively. The BSC or MMI can activate

either of the two software versions to run or load new versions. The BSC or MMI can

get the software version information of all the boards from the TMU, and display the

information at the graphical interface.

5.5.2 Abis Interface Management

I. Abis interface management

Abis interface is a standard interface between BTS and BSC, which takes the TS

switching equipment as the main object of its management. It also involves the

management of part of the data link layers.


5-13




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.


5-14




The logical channel parameters mainly include the channel types, and the

messages appeared on them, especially the system message, which are

determined by the attributes of both the channel and the cell.

I. BTS attributes setting

BTS attributes refer to the parameters applicable to the whole cell, but not related to

specific carriers and channels, including:

1) Interference level limit

2) Interference average value

3) Connection failure decision threshold: the BER or the receiving level threshold.

4) T200, including the T200 timing values of the following channels:

SDCCH

FACCH (full rate) FACCH (half rate)

SACCH (relevant to TCH, SAPI=0)

SACCH (relevant to SDCCH)

SDCCH (SAPI=3)

SACCH (relevant to TCH, SAPI=3)

5) Maximum timing advance

6) Overload indication period

7) CCCH load threshold

8) CCCH load indication period

9) RACH busy decision threshold

10) RACH load average TS number

11) BTS air timer

12) Maximum number of physical channel message retransmissions (Ny1)

13) BCCH absolute RF number

14) Base station identification code (BSIC)

15) Configuration start time

II. Carrier frequency attributes setting

The carrier frequency attributes are the parameters relevant to the specific carrier

frequency, which include:

Maximal power descending of the RF

RF absolute channel numbers table

III. Channel attributes setting

The channel attributes refer to the parameters related to the specific channel,

including:

Channel combination mode

Frequency hopping serial number


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Mobile allocation index offset (MAIO)

RF absolute channel numbers table

Configuration start time

Training sequence number

IV. Air interface management extension

The operation and maintenance protocol of the base stations is mainly stipulated in

GSM 12.21 standards. This protocol is not yet perfect, and should be extended in

actual applications.

The BTS30 protocol extension includes two aspects: the setting of BTS extended

attributes (frequency hopping modes etc.), and the setting of sites extended

attributes, including environment parameters and clock hardware parameters (phase

locking reference source, DAC values). 5.5.4 Testing Management

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

operation of the base station.


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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

classified into one of the following categories:


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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

time.


5-18




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

necessary emergency processing measures.


5-19




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

saved in the log buffer area.


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5.5.10 Other Functions

I. Attributes query

Most of the attributes of managed objects are configured by the BSC during base

station initialization, and part of them may be modified during the operation. Any of

the attributes can be queried during maintenance, which is helpful to decide the

operation status of the base station.

II. Alarm threshold setting

Different threshold values can be set through OMC for the protection of different

objects so as to avoid system down. For example, alarm limits can be set on the RF

working power and the standing-wave ratio etc.

III. OML link test

In order to guarantee the proper operation of OML link and to supervise its status,

the BSC transmits some routine messages to the TMU to supervise this link. In

addition, the BSC realtime clock is also transmitted, which is used as the TMU

superior level clock reference.

IV. Transparent commands

For debugging convenience and adding of new functions, transparent commands

can be used to flexibly transfer some customized commands or debugging

commands to some designated boards.

V. Query on-site board

The on-site board refers to the board which has been installed in the slot and hasn’t

been configured on the data configuration console. This kind of boards can be

queried on the board maintenance panel and are differentiated by color.

5.6 System Indices

I. Power consumption

Test conditions: temperature: 25®C; relative humidity: 80%; power amplifier power

output: 40W. Measured at the inlet of the cabinet power supply (the output of the

primary power supply) 30 minutes after the power-on and normal working of the

system.

The power consumption of the cabinet in different configurations are listed in

Table 5-1.


5-21




Table 5-1 Power consumption of the BTS30 in different configurations

Number of TRXs Voltage (V) Current (A) Power consumption (W)

6 26.8 44.3 1187

5 26.8 37.8 1013

4 26.8 31.2 836

3 26.8 24.7 662

2 26.8 17.2 461

1 26.8 10.7 287

II. Clock

Frequency: 1.3×107 Hz, with the precision upon leaving the factory better than 0.1

Hz.

Frequency deviation varied with temperature changes: < ± 0.05 ppm (temperature

from 0®C to 70®C). Annual aging rate: < ± 0.1 ppm.

III. Environmental conditions

Since the BTS30 is an indoor base station, the automatic air-conditioning system is

required in the room.

It can work smoothly within the temperature range -5®C~+45®C under 15-85%

relative humidity.

The environmental alarm box is available to supervises the environmental

parameters and report the alarms.

IV. System reliability

Table 5-2 The mean time between failures (MTBF) of BTS30

No. Cell confi guration Failure rate accumulated (10-6h) MTBF(h)

1 O(1) 37.452 35000

2 O(2) 33.996 30000

3 S(2/2/2) 56.560 18000

4 S(4/4/4) 75.414 15000

5 S(6/6/6) 97.834 11000


5-22




V. Physical characteristics

Dimensions: 1600 mm (H) × 600 mm (W) × 450 mm (D). Weight: Empty cabinet 85 kg.

Fully configured cabinet 180kg. 5.7 Radio Interface Indices

I. The functional frequencies of M900 BTS30

Uplink (MHz) Downlink (MHz)

Primary band 890-915 935-960

II. The functional frequencies of M1800 BTS30

Up Link (MHz) Down Link (MHz)

Primary band 1710-1785 1805-1880

5.7.1 Receivers

I. Receiving sensitivity

Testing conditions: FCH/FS channel, no frequency hopping, BER and frame deletion

rate meet the requirements of Table 1 of GSM 05.05 standards.

1) M900 BTS

Static sensitivity: better than -110dBm.

Multipath sensitivity: better than -104dBm under TU3, TU50, RA250 and HT100

transmission conditions.

2) M1800 BTS

Static sensitivity: better than -109dBm.

Multipath sensitivity: better than -104dBm under TU3, TU50, RA250 and HT100transmission conditions.

II. Receiver input level range

1) M900 BTS

In the static transmission condition, the relationship between the input levels and the

M900 BTS Type II BER measured on the TCH/FS channel is given in Table 5-3:

Table 5-3 Relationship between the M900 BTS Type II BER and input levels

Input level range Static sensitivity level~-84dBm -84dBm~-40dBm -40dBm~-15dBm


5-23




Type II BER <2 % <10-4 <10-3

2) M1800 BTS

In the static transmission condition, the relationship between input levels and M1800

BTS Type II BER measured on the TCH/FS channel is given in Table 5-4:

Table 5-4 Relationship between the M1800 BTS Type II BER and input levels

Input level range Static sensitivity level~-84dBm -84dBm~-40dBm -40dBm~-23dBm

Type II BER <2 % <10-4 <10-3

III. Blocking features

1) M900 BTS

When the sine wave interference signals with frequency and level as shown in

Table 5-5 are input together with the -101dBm useful signals into the M900 BTS

receiver, the BER still meets the requirements.

Table 5-5 Frequency and level of M900 BTS sine wave interference signals

Frequency (inband) 600kHz |f-f 0|<800kHz 800kHz |f-f 0|<3.0MHz 3.0MHz |f-f 0|

Level (dBm) -26 -16 -13

Frequency (outband) 0.1MHz f<870MHz 925MHz f<12750MHz

Level (dBm) 0 0

Where f 0 is the useful signal frequency, and f is the interference signal frequency. 2) M1800 BTS

When the sine wave interference signals with frequency and voltage level as shown

in Table 5-6 are input together with the -101dBm useful signals into the M1800 BTS

receiver, the BER still meets requirements

Table 5-6 Frequency and level of M1800 BTS sine wave interference signals

Frequency (inband) 600kHz |f-f 0|<800kHz 800kHz |f-f 0|<3.0MHz 3.0MHz |f-f 0|

Level (dBm) -35 -25 -25

Frequency (outband) 0.1MHz f<1690MHz 1805MHz f<12750MHz

Level (dBm) 0 0

Where f 0 is the useful signal frequency, and f is the interference signal frequency.


5-24




IV. C/I and bit error code rate

When the useful signal is -84dBm, relationship between the TCH/FS channel TYPE

II BER and C/I measured under the non-hopping multipath condition is shown as in

Table 5-7. This relationship in M900 is the same as that in M1800.

Table 5-7 Relationship between the BTS TYPE II BER and C/I

Interf erence frequency C/I(dB) TCH/FS TYPE II BER

f = f 0 9 TU1.5 RBER<4.0%

| f - f 0| = 200kHz -9 TU50 RBER<8.1%

| f - f 0| = 400kHz -41 TU50 RBER< 8.1%

f is the random continuous GSM modulated interference signal frequency, and f 0 is

the useful signal frequency.

V. Inter-modulation response suppression

1) M900 BTS

For M900 BTS, when the useful signals with a sensitivity 3dB higher than the

reference sensitivity are input to the receiver simultaneously with two -43dBm

interference signals, the TYPE II BER measured on the TCH/FS channel is better

than 2%, and the carrier relationship and modulation forms of interference signalssatisfy GSM 11.21 specifications.

2) M1800 BTS

For M1800 BTS, when the useful signals with a sensitivity 3dB higher than the

reference sensitivity are input to the receiver simultaneously with two -49dBm

interference signals, the TYPE II BER measured on the TCH/FS channel is better

than 2%, and the carrier relationship and modulation forms of interference signals

meet GSM 11.20 specifications.

VI. Stray radiation The testing result is the same for both M900 BTS and M1800 BTS:

Radiation within 9kHz~1GHz: <-57dBm

Radiation within 1GHz~12.75GHz: <-47dBm


5-25




5.7.2 Transmitters

I. Average carrier frequency power

For M900 BTS and M1800 BTS, the average carrier frequency power of the

transmitter measured at the combiner input end is 46dBm with a tolerance of

±1dBm.

II. Power Control

1) Static power control

Both the M900 BTS and M1800 BTS transmitters have 10 levels for static power

adjustment, with a step length of 2±1dB. On each static power level, the absolute

precision is better than ±3dB.2) Dynamic power control

Both the M900 BTS and M1800 BTS transmitters have 15 levels for dynamic power

adjustment, with a step length of 2±1.5dB. On each dynamic power level, the

absolute precision is better than ±3dB.

III. Carrier frequency envelope

Power flatness of the 147 bit useful part: <±1dB.

Cutoff timeslot power: <-30dBc.

The ramping up and down of the power bursts is in accordance with the

power-versus-time template (Figure 5-5).

+4+1-1-6

-30

10 8 10 10 8 10542.8t(us)

dB

Figure 5-5 Power-versus-time template

Note: Testing results are the same for both M900 and M1800 BTSs.


5-26




IV. Transmission spectrum

1) Modulated spectrum

Power of various deviating frequency points of M900 and M1800 BTSs are shown in

Table 5-8 and Table 5-9 respectively.

Table 5-8 Power of various deviating frequency points of M900 BTS

Frequencydeviation

100kHz 200kHz 250kHz 400kHz600kHz~1.2MHz

1.2MHz~1.8MHz

1.8MHz~6MHz

ƒ 6MHz

Max. powerlevel (dBc)at relativecarrier

0.5 -30 -33 -60 -70 -73 -75 -80

Table 5-9 Power of various deviating frequency points of M1800 BTS

Frequencydeviation

100kHz 200kHz 250kHz 400kHz600kHz~1.2MHz

1.2MHz~1.8MHz

1.8MHz~6MHz

ƒ 6MHz

Max. powerlevel (dBc)at relativecarrier

0.5 -30 -33 -60 -70 -73 -75 -80

2) Transient spectrum

For M900 and M1800 BTSs, the power levels caused by handover at the various

deviating frequency points are shown in Table 5-10 and Table 5-11 respectively.

Table 5-10 Power levels of M900 BTS caused by handover at various deviating frequency points

Frequency deviat ion 400kHz 600kHz 1.2MHz 1.8MHz

Maximum power level (dBc) ofrelative carrier

-57 -67 -74 -74

Table 5-11 Power levels of M1800 BTS caused by handover at various deviating frequency points

Frequency deviat ion 400kHz 600kHz 1.2MHz 1.8MHz

Maximum power level (dBc) ofrelative carrier

-50 -58 -66 -66

V. Intermodulation suppression

1) M900 BTS


5-27




For interference signals coming from the antenna into the transmitter, the

intermodulation signal suppression of the transmitter is over 70dBc (or under

-36dBm), and the levels of the 3rd order and 5th order intermodulation signals falling

within the 890~915MHz frequency band are under -98dBm.

The suppression of the intermodulated signal after multi-carrier combination is over

70dBc (or under -36dBm) when it falls within the 935MHz~960MHz frequency band,

and that falling within the 890MHz~915MHz frequency band has an output level

under -98dBm.

2) M1800 BTS

For interference signals coming from the antenna into the transmitter, the

intermodulation signal suppression of the transmitter is over 70dBc (or under

-36dBm), and the levels of the 3rd order and 5th order intermodulation signals falling

within the 1710~1785MHz frequency band are under -98dBm.

The suppression of the intermodulated signal after multi-carrier combination is over

70dBc (or under -36dBm) when it falls within the 1805MHz~1880MHz frequency

band, and that falling within the 1710MHz~1785MHz frequency band has an output

level under -98dBm.

VI. Spurious emission

Conductive stray radiation measured at antenna connection points meets the

following requirements:1) M900 BTS

9kHz~1GHz: <-36dBm

890MHz~915MHz: <-98dBm

1GHz~12.75GHz: <-30dBm

2) M1800 BTS

9kHz~1GHz: <-36dBm

1710MHz~1785MHz: <-98dBm

1GHz~12.75GHz: <-30dBm

VII. Frequency deviation and phase deviation

Transmitting signal frequency deviation: <0.05ppm

Transmitting signal phase deviation: <5°(rms)

<20°(peak)

Note: For M900 BTS and M1800 BTS, the testing results are same.

Date post:	03-Jun-2018
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05-Functions and Performance

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