Bscrnc Clock

BSC/RNC Clock Feature Parameter Description

Copyright Huawei Technologies Co., Ltd. 2010. All rights reserved.

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Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

SRAN Contents

Issue 01 (2010-01-20) Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

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Contents 1 Introduction ................................................................................................................................1-1

1.1 Scope ............................................................................................................................................ 1-1 1.2 Intended Audience ........................................................................................................................ 1-1 1.3 Change History.............................................................................................................................. 1-1

2 Overview of BSC/RNC clock ..................................................................................................2-1

3 BSC/RNC Clock Synchronization .........................................................................................3-1 3.1 Overview ....................................................................................................................................... 3-1 3.2 BSC/RNC Synchronization System Structure............................................................................... 3-2 3.3 RFN Generation Process .............................................................................................................. 3-3

4 Engineering Guidelines...........................................................................................................4-1 4.1 Configuration of GPS Clock Source.............................................................................................. 4-1 4.2 Configuration of Gb Interface Clock.............................................................................................. 4-1

5 Parameters .................................................................................................................................5-1

6 Counters......................................................................................................................................6-1

7 Glossary ......................................................................................................................................7-1

8 Reference Documents .............................................................................................................8-1

SRAN BSC/RNC Clock 1 Introduction


1-1

1 Introduction 1.1 Scope This document describes the types, synchronous system structure, and RFN generation process of the BSC/RNC clock (MRFD-210502 BSC/RNC Clock).

1.2 Intended Audience This document is intended for:

z Personnel who need to understand the BSC/RNC clock z Personnel who work with Huawei products

1.3 Change History This section provides information on the changes in different document versions.

There are two types of changes, which are defined as follows:

z Feature change: refers to the change in the BSC/RNC Clock feature of a specific product version. z Editorial change: refers to the change in wording or the addition of the information that was not

described in the earlier version.

Document Issues The document issues are as follows:

z 01 (2010-01-12)

01 (2010-01-12) This is the first commercial release of SRAN3.0.

SRAN BSC/RNC Clock 2 Overview of BSC/RNC clock


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2 Overview of BSC/RNC clock The BSC/RNC clock supports five types of clock sources. All the clock sources support 1+1 backup, clock source management, clock status query, and line clock maintenance. The clock source backup function can eliminate the impact on the services when the primary clock becomes invalid.

SRAN BSC/RNC Clock 3 BSC/RNC Clock Synchronization


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3 BSC/RNC Clock Synchronization 3.1 Overview The BSC/RNC clock provides reliable clock sources for the BSC/RNC to meet the requirements of the clock precision defined in the 3GPP specifications. Every type of clock source supports 1+1 backup.

The BSC/RNC clock subsystem consists of the clock processing board GCUa/GCGa and the clock processing unit in each subrack. The external reference clock signals are transmitted to the GCUa/GCGa. After a phase lock on the GCUa/GCGa, the clock signals are changed to 8 KHz clock signals. The signals are then transmitted to the SCUa in the same subrack through the backplane and to the SCUa in the EPS through clock signal cables. Then, the 8 KHz clock signals on the SCUa are transmitted to other boards in the same subrack through the backplane.

When the clock source is faulty, the BSC/RNC reports the related alarms and starts the 1+1 backup scheme to ensure the normal operation of the system.

The BSC/RNC clock sources are as follows:

z BITS clock BITS clock is categorized into the following types: 2 MHz, 2 Mbit/s, and 1.5 Mbit/s clocks. The 2 MHz and 2 Mbit/s clocks use E1 clock signals, whereas the 1.5 Mbit/s clock uses T1 clock signals. BITS clock has two input modes, that is, BITS0 and BITS1. The two input modes correspond to the two input ports (CLKIN0 and CLKIN1) on the GCUa/GCGa. The parameters REF2MCLKSW1 and REF2MCLKSW2 are used to enable the switch of 2M BITS clock.

z Line clock extracted from the A/Iu interface The line clock signals are transmitted to the GCUa/GCGa through the A/Iu interface and are changed to 8 kHz clock signals. Then, clock signals are transmitted to the GCUa/GCGa through the backplane in the MPS. The clock signals have two input modes, that is, LINE0 and LINE1. The parameters BACK8KCLKSW1 and BACK8KCLKSW2 are used to enable the switch of backplane LINE clock.

z GPS clock The GPS clock uses the 1PPS signals extracted from the global positioning system (GPS). The GCGa is embedded with the GPS card. Through the satellite antenna interface on the GCGa, clock signals can be received from the GPS.

z 8 kHz clock provided by the external clock source The 8 kHz standard clock is obtained from the external device through the COM1 port on the GCUa/GCGa.

z Clock generated by the local oscillator The BSC uses the clock generated by the local oscillator if no clock is configured.

You can run the MML command ADD CLKSRC to configure the parameter SRCT to set the clock source type.

The BSC/RNC has the clock control setting functions such as the clock source management, clock status query, and line clock maintenance. The BSC/RNC uses only clock source during operation. The clock source has three operating modes, that is, automatic mode, manual mode, and self-oscillation mode.

z Automatic mode

3 BSC/RNC Clock Synchronization SRAN

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3-2 Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

Issue 01 (2010-01-20)

Users need not specify the clock source. The system can automatically select the clock source with the highest priority.

z Manual mode Users need to specify the clock source and the system cannot automatically switch the clock source to other clock sources (even if the current specified clock source is faulty).

z Self-oscillation mode The self-oscillation mode is the initial operating mode of the BSC/RNC clock.

You can run the MML command SET CLKMODE to configure the parameter MODE to set the clock mode.

3.2 BSC/RNC Synchronization System Structure The clock synchronization system consists of the clock board, subrack backplane, inter-subrack clock cables, and clock module of each board. Figure 3-1 shows the structure of the clock synchronization system.

Figure 3-1 Structure of the clock synchronization system

The clock board of the BSC6900 consists of the GCUa and GCGa. The BSC6900 can configure either the GCUa or the GCGa according to the clock type. You can run the MML command SET CLKTYPE to configure the parameter CLKTYPE to set the type of a clock board.

If the interface board where clock signals are extracted from the CN is in the MPS, clock signals can be directly transmitted to the clock board through LINE0/LINE1 on the backplane in the MPS or through the 2 MHz clock output port (using the clock signal cable) on the panel of the interface board.

If the interface board where clock signals are extracted from the CN is in the EPS, clock signals can be transmitted to the clock board in the MPS through only the 2 MHz output port on the panel of the interface board.

If the interface board where clock signals are extracted from the CN is in the TCS, clock signals are transmitted to the Ater interface board through the backplane, and transmitted to the Ater interface board in the MPS through the inter-subrack cable of the Ater interface, and then transmitted to the clock board through the channels on the backplane in the MPS.

SRAN BSC/RNC Clock 3 BSC/RNC Clock Synchronization


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When the CS clock and PS clock are not obtained from the same clock source, the Gb interface board can extract clock signals either from the backplane in the subrack or from the CN side provided that the BSC6900 is configured with the Gb interface board. When extracting clock signals from the CN side, the Gb interface board cannot be shared by other interfaces. If the CS clock and the PS clock have different clock sources, the parameter REFUSELOCALCLK need to be set to YES, and then the CS clock can use the clock source of the PS clock.

Figure 3-2 shows the clock cable connections between the clock board in the MPS and the SCUa in the EPS when the BSC6900 is configured with the active and standby clock boards and active and standby SCUa boards.

Figure 3-2 Structure of the clock synchronization system

The active and standby clock boards in the MPS are connected to the active and standby SCUa boards in the EPS through the Y-shaped clock cable. This connection mode can ensure the normal operation of the system clock even if the single-point failure occurs among the clock cable, Y-shaped clock cable, and SCUa. In addition, the Y-shaped clock cable can ensure the normal operation of the SCUa when the active and standby clock boards are switched over. In the MPS, clock signals are transmitted from the clock board to the SCUa in the subrack through the channels on the backplane. In this case, the Y-shaped clock cable is not required.

3.3 RFN Generation Process The RNC frame number (RFN) is used for the RNC node synchronization. The RFN is contained in the node synchronization frame that the RNC sends to the NodeB.

Figure 3-3 shows the RFN generation and reception process and takes the GCUa as an example.

Figure 3-3 RFN generation and reception process

3 BSC/RNC Clock Synchronization SRAN

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The GCUa/GCGa in the MPS transmits 1PPS signals and time synchronization packets to the SCUa boards in this subrack and other subracks, and then transmits signals to other boards in the subrack through the SCUa. The boards generate the required RFN signals according to the received 1PPS signals and time synchronization packets.

1PPS signals can be generated on the GCUa/GCGa. If the clock board is the GCGa, GPS signals can be extracted from the GPS card to generate 1PPS signals that are synchronous with the satellite signals.

SRAN BSC/RNC Clock 4 Engineering Guidelines


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4 Engineering Guidelines 4.1 Configuration of GPS Clock Source If the clock source is the GPS, the GCUa must be configured.

The clock source configuration command is as follows:

ADD CLKSRC: SRCGRD=3, SRCT=GPS;

The GCUa configuration command is as follows:

SET CLKTYPE: CLKTYPE=GCUa

4.2 Configuration of Gb Interface Clock In special 2G networking scenarios, if the CS clock is not synchronized with the PS clock, the Gb interface clock needs to be configured as the SGSN node-locked clock. The configuration command is as follows:

SET CLK: SRT=MPS, SN=0, BT=PEUa, REF2MCLKSRC=0, REF2MCLKSRCBAK=0, REFUSELOCALCLK=YES;

Note: Only the PEUa whose logical type is FR supports the local clock.

SRAN BSC/RNC Clock 5 Parameters


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5 Parameters The following describes the parameters related to BSC/RNC Clock feature.

Table 5-1 Parameter description

Parameter ID NE MML Description

REF2MCLKSW1

BSC6900 SET CLK(Optional)

Meaning: Switch of panel BITS1(2M) GUI Value Range: OFF(OFF), ON(ON) Actual Value Range: OFF, ON Unit: None Default Value: OFF

REF2MCLKSW2


Meaning: Switch of panel BITS2(2M) GUI Value Range: OFF(OFF), ON(ON) Actual Value Range: OFF, ON Unit: None Default Value: OFF

BACK8KCLKSW1


Meaning: Switch of backplane LINE1 GUI Value Range: OFF(OFF), ON(ON) Actual Value Range: OFF, ON Unit: None Default Value: OFF

BACK8KCLKSW2


Meaning: Switch of backplane LINE2 GUI Value Range: OFF(OFF), ON(ON) Actual Value Range: OFF, ON Unit: None Default Value: OFF

SRCT BSC6900 ADD CLKSRC(Mandatory)

Meaning: Type of the clock source. GUI Value Range: BITS1-2MHZ(2MHZ Building Integrated Timing Supply system 1), BITS2-2MHZ(2MHZ Building Integrated Timing Supply system 2), BITS1-2MBPS(2MBPS Building Integrated Timing Supply system 1), BITS2-2MBPS(2MBPS Building Integrated Timing Supply system 2), 8KHZ(8KHZ), GPS(Globe Positioning System), LINE1_8KHZ(8KHZ line1), LINE2_8KHZ(8KHZ line2), BITS1-T1BPS(T1BPS Building Integrated Timing Supply system 1), BITS2-T1BPS(T1BPS Building Integrated Timing Supply system 2) Actual Value Range: BITS1-2MHZ, BITS2-2MHZ, BITS1-2MBPS, BITS2-2MBPS, GPS, 8KHZ, LINE1_8KHZ, LINE2_8KHZ, BITS1-T1BPS, BITS2-T1BPS Unit: None Default Value: None

5 Parameters SRAN

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Parameter ID NE MML Description

MODE BSC6900 SET CLKMODE(Mandatory)

Meaning: Working mode of the system clock. Working modes of the system clock are as follows:(1) MANUAL: In this mode, you must specify a clock source and prevent the switching of the clock source. (2) AUTO: In this mode, you do not need to specify a clock source and the system automatically selects the clock source with the highest priority. (3) FREE: In this mode, the crystal oscillator of GCU board is used. GUI Value Range: MANUAL(Manual Handover), AUTO(Auto Handover), FREE(Free-run) Actual Value Range: MANUAL, AUTO, FREE Unit: None Default Value: AUTO

CLKTYPE BSC6900 SET CLKTYPE(Mandatory)

Meaning: Type of the clock board GUI Value Range: GCUa, GCGa Actual Value Range: GCUa, GCGa Unit: None Default Value: None

REFUSELOCALCLK


Meaning: Whether to use SGSN clock source.Only the Gb interface board needs to set this parameter. If the SGSN clock and the MSC clock have different clock sources, the MSC clock must use the clock source of the SGSN clock. If the two clocks use the same clock source, this parameter does not need to be set. GUI Value Range: NO(NO), YES(YES) Actual Value Range: NO, YES Unit: None Default Value: NO

SRAN BSC/RNC Clock 6 Counters


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6 Counters There are no specific counters associated with this feature.

SRAN BSC/RNC Clock 7 Glossary


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7 Glossary For the acronyms, abbreviations, terms, and definitions, see the Glossary.

SRAN BSC/RNC Clock 8 Reference Documents


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8 Reference Documents There are no specific reference documents associated with this feature.

1 Introduction 1.1 Scope 1.2 Intended Audience 1.3 Change History 2 Overview of BSC/RNC clock 3 BSC/RNC Clock Synchronization 3.1 Overview 3.2 BSC/RNC Synchronization System Structure 3.3 RFN Generation Process

4 Engineering Guidelines 4.1 Configuration of GPS Clock Source 4.2 Configuration of Gb Interface Clock

5 Parameters 6 Counters 7 Glossary 8 Reference Documents