ibsc structure and principle 91

ZXG10 iBSCStructure and Principle

ZTE UNIVERSITYZTE University, DameishaYanTian District, Shenzhen,P. R. China518083Tel: (86) 755 26778800Fax: (86) 755 26778999URL: http://ensupport.zte.com.cnE-mail: [email protected]

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Publishing Date (MONTH/DATE/YEAR) : 20091111

Content

ZXG10 iBSC Structure and Principle ............................. 1

1 Overview................................................................... 21.1 System Background ............................................................... 2

1.2 System Position in Network..................................................... 2

1.3 Cabinet Appearance ............................................................... 3

1.4 System Features ................................................................... 3

1.5 Services and Functions........................................................... 4

2 System Indices........................................................ 132.1 Physical Indices....................................................................13

2.1.1 Dimensions .................................................................13

2.1.2 Overall Weight .............................................................13

2.2 Power Supply Indices ............................................................14

2.2.1 Power Supply Range .....................................................14

2.2.2 Power Consumption ......................................................14

2.3 Environmental Requirements..................................................14

2.3.1 Grounding Requirement ................................................14

2.3.2 Temperature and Humidity Requirement..........................15

2.3.3 Air Quality Requirement ................................................15

2.3.4 Barometric Requirement................................................15

2.4 Clock Indices .......................................................................15

2.5 Reliability Indices .................................................................16

2.6 Interface Types ....................................................................16

2.7 Capacity Indices ...................................................................17

3 Hardware Structure................................................. 193.1 Cabinet Layout.....................................................................19

3.2 Shelves...............................................................................20

3.3 Boards ................................................................................20

3.4 Shelf Configuration and Principle ............................................24

3.4.1 Control Shelf (BCTC).....................................................24

3.4.2 Switch Shelf (BPSN) .....................................................27

3.4.3 Resource Shelf (BGSN) .................................................30

3.4.4 Connection Between Shelves .........................................33

3.5 Equipment Configuration .......................................................38

4 Software Structure.................................................. 434.1 Foreground Software.............................................................43

4.2 Background Software ............................................................45

5 System Principle...................................................... 475.1 Logic Units ..........................................................................47

5.1.1 O&M Unit ....................................................................48

5.1.2 Processing Unit ............................................................49

5.1.3 BIU ............................................................................49

5.1.4 AIU ............................................................................51

5.1.5 PCU............................................................................53

5.1.6 TCU............................................................................55

5.1.7 PSU............................................................................55

5.2 User Plane Data Flow ............................................................56

5.2.1 User Plane Data Flow in CS Domain ................................56

5.2.2 User Plane Data Flow in PS Domain ................................57

5.3 Control Plane Signal Flow ......................................................58

5.3.1 Control Plane Signal Flow in CS Domain ..........................58

5.3.2 Control Plane Signal Flow in PS Domain...........................60

6 Interface and Protocol............................................. 656.1 Interfaces............................................................................65

6.1.1 A-Interface..................................................................65

6.1.2 Ater Interface (TC Is External) .......................................65

6.1.3 Abis Interface ..............................................................66

6.1.4 Gb Interface ................................................................66

6.1.5 OMC Interface .............................................................67

6.1.6 CDR Interface ..............................................................67

6.2 Protocols .............................................................................67

6.2.1 CS Domain Protocols ....................................................67

6.2.2 PS Domain Protocols.....................................................73

7 Networking ............................................................. 777.1 Abis Interface Networking Modes ............................................77

7.2 A-Interface Networking Mode .................................................79

7.3 Ater Interface Networking Mode .............................................80

7.4 Gb Interface Networking........................................................81

7.5 OMC Interface Networking Modes ...........................................81

8 Operation and Maintenance..................................... 858.1 Maintenance Overview ..........................................................85

8.2 Maintenance Functions ..........................................................86

ZXG10 iBSC Structureand PrincipleAfter you have completed this course, you

will be able to:

>> Learn the iBSC system funcations andfeatures

>> Learn the iBSC system indices, includeit's dimension, capacity etc.

>> Learn the iBSC hardware and softwarestructure

>> Learn the iBSC work principle and sig-nal flow

>> Learn the iBSC networking and config-uration

>> Learn the iBSC operation and mainte-nance mode

Confidential and Proprietary Information of ZTE CORPORATION 1

ZXG10 iBSC Structure and Principle

Chapter1 Overview

After you have completed this chapter, you will know:

>> System Background>> System Position in Network>> Cabinet Appearance>> System Features>> Services and Functions

1.1 System BackgroundGSM, which is the second generation mobile cell communicationsystem and takes voice service as its primary service, has beenextensively applied in the world. However, with the developmentof mobile communication technology and the diversification of ser-vice, demands on mobile data service are increasing. Data servicedemands for GSM equipments become more and more urgent, in-cluding IP Gb interface, Iu interface interconnection, large-capac-ity data interface, and integration with 3G service.

To meet such demands, ZTE has self-developed iBSC.

1.2 System Position in Network� The position of iBSC in the network is shown in Figure 1.

FIGURE 1 POSITION OF IBSC IN NETWORK

2 Confidential and Proprietary Information of ZTE CORPORATION

Chapter 1 Overview

iBSC is a part of GERAN. GERAN includes one or multiple BSSs,and one BSS consists of one BSC and one or multiple BTSs. BSCis connected with BTS through Abis interface, and GERAN is con-nected with CN through A/Gb interface.

1.3 Cabinet AppearanceFigure 2 shows the appearance of iBSC.

FIGURE 2 IBSC CABINET APPEARANCE

The iBSC cabinet satisfies the CompactPCI standard. The frontdoor is navy blue, with dense vents. The cabinet body is navyblue.

1.4 System FeaturesiBSC is the large-capacity base station controller developed by ZTECorporation. It has the following features:



� All-IP hardware platform

iBSC employs the all-IP hardware platform which is the sameas that of ZTE 3G products. The all-IP-based hardware plat-form ensures powerful PS service capability and facilitates theimplementation of IP Abis interface and IP Gb interface.

� Large capacity and strong processing capability

iBSC supports 1536 sites and 3072 carriers at most. Its pro-cessing capability is very powerful, which reduces the network-ing complexity, improves the network quality, and saves theinvestment in equipment room.

� Standard A-interface

iBSC provides completely open A-interface to ensure the inter-connection with equipments of different vendors.

� Modular design and easy capacity expansion

iBSC employs modular design, which facilitates the capacityexpansion. The smooth capacity expansion can be imple-mented by module overlay.

� Flexible networking modes

iBSC supports star networking, chain networking, tree net-working, and ring networking at Abis interface. It also supportstransmission equipments such as E1, satellite, microwave, andoptical fiber.

� High integration and low power consumption

iBSC is highly integrated and occupies less area, which savesthe investment in equipment room.

iBSC has a low power consumption, which reduces the opera-tor's investment in auxiliary power supply and air conditioner.

� High reliability

The key components of iBSC employs 1+1 redundancy backup,which increases the system reliability.

1.5 Services and FunctionsiBSC supports the service functions of base station controller inGSM Phase II and Phase II+ standards. It performs the followingfunctions.

1. Supports GSM 900, GSM 850, GSM 1800 and GSM 1900 net-work.

2. Supports the base station management functions specified inthe standards. It can manage the hybrid access of ZXG10 BTSseries products.

3. Through the connection between OMC interface and NetNumenM31, implements operation and maintenance management ofBSS.

4. Supports various types of services.

i. Circuit voice service


Chapter 1 Overview

– Full rate voice service

– Enhanced full rate voice service

– Half rate voice service

– AMR voice service

AMR is one of the voice coding algorithms, with variablerate. It adjusts the voice coding rate automatically ac-cording to the C/I value to ensure the best voice qualityunder different C/I.

According to the protocol, AMR-FR has 8 voice codingrates, and iBSC supports all the 8 modes. AMR-HR has5 voice coding rates, that is, 7.4 kbps, 6.7 kbps, 5.9kbps, 5.15 kbps, and 4.75 kbps, all are supported byiBSC.

ii. Circuit data service

– 14.4 kbps full rate data service




iii. Short message service

– Point to point SMS when MS is the called party

– Point to point SMS when MS is the calling party

– Cell broadcast service from SMS center or operation &maintenance system

iv. GPRS service

At present, available services are point to point interactivetelecommunication services, including accessing database,session service, and teleaction service.

v. EDGE service

5. Supports channel management, including ground channelmanagement, service channel management, and controlchannel management.

i. Ground channel management

It includes ground channel management between MSC andBSC, ground channel management between BSC and BTS,and channel management between BSC and SGSN.

ii. Service channel management includes channel allocation,link monitoring, channel release, and function control de-cision.

iii. Control channels supported: FCCH, SCH, BCCH, PCH,AGCH, RACH, SDCCH, SACCH, FACCH, PACCH, PAGCH,PBCCH, PCCCH, PPCH, PRACH, and PTCCH.

6. Supports frequency hopping.

7. Supports DTX and VAD.

8. Supports multiple handover types.

Supports synchronous handover, non-synchronous handover,and pseudo-synchronous handover.



Supports handover within 900 MHz band and 1800 MHz band,and handover between 900 MHz band and 1800 MHZz band.

Implements handover measurement and handover.

Supports handover originated by network due to service or in-terference management.

Supports handover between channels with different voice cod-ing rate.

Supports handover when DTX is used.

Supports handover due to traffic problems.

Supports concentric circle handover based on Carrier-to-Inter-ference (C/I) ratio.

9. Supports 6-level static power control and 15-level dynamicpower control of MS and BTS. Supports fast power controlbased on reception quality.

10.Supports overload and flow control.

iBSC can locate and analyze the overload problem and sendthe fault cause to the background. If the traffic is too heavy,it controls the flow at A–interface, Abis interface, and/or Gbinterface to reduce the flow and guarantee the maximum trafficcapability.

11.Supports call-reestablishment when radio link is faulty

12. iBSC supports call queuing and forced call release during as-signment and handover.

13.Supports preferential access for high–end users.

High–end user's preferential access is also called high–priorityuser's preferential access or Enhanced Multi-Level Precedenceand Preemption service (EMLPP). It divides mobile users intodifferent priorities, and allocates the channel resource to usersaccording to their priority. The higher the priority of a user is,the easier the user accesses the network.

14.Supports Co-BCCH.

Co-BCCH is usually applied in dual-frequency shared cell. Thedual-frequency shared cell is a cell that supports carriers of twofrequency bands, and the carriers of different frequency bandsshare one BCCH.

The co-BCCH networking has the following advantages:

� Saving one BCCH time slot.

� Configuring the 1800 MHz carrier directly in 900 MHz cell.There is no need to change the original adjacent cell rela-tionship and replan the network, and it is unnecessary toconsider problems such as reselection and handover be-tween dual-frequency cells within the same site.

15.Supports dynamic HR channel conversion.

iBSC supports dynamic HR channel conversion. The systemcan adjust HR/FR channels dynamically according to the trafficand implement conversion between HR channel and FR channelautomatically.

16. Supports flow control.


Chapter 1 Overview

Flow control is a method for protecting the system. It controlsthe overload by limiting some services to ensure that the sys-tem runs normally.

17. Supports dynamic radio channel allocation.

iBSC supports the dynamic allocation of CS channels and PSchannels.

In dynamic radio channel allocation, the logic type of radiochannel is generated according to the current call type ratherthan configured at background network management system.The advantage of dynamic radio channel is that it uses theradio resource the best according to the service type.

iBSC allocates the channel according to various factors, includ-ing channel rate, carrier priority, interference band, channelallocation during intra-cell handover, allocation of reservationchannels, and selection of sub-cell channels.

18. Supports voice version selection.

iBSC provides the function of setting prior voice version, that is,setting a prior voice version for full rate channel and half ratechannel respectively. Full rate voice version is one of the fol-lowing: version I (FR), version II (EFR) and version III (AMR);half rate voice version is one of the following: version I (HR)and version III (AMR).

19. Supports 3–digit network number.

iBSC supports 3–digit network number. The current networknumber can be 2 or 3 digits. It interprets MNC in the signalingmessage received at A-interface and Gb interface, decides theMNC format in the transmitted signaling, and decides the MNCformat in the broadcast message at Um interface according tothe network number.

20.Supports the handover between 2G system and 3G system.

� Supports incoming handover from 3G system to 2G systemin CS service.

� Support outgoing handover from 2G system to 3G systemin CS service

21.Supports full dynamic Abis function.

Full dynamic Abis means that the corresponding relation of ra-dio channel and Abis transmission channel is not generatedby the operation & maintenance system, but is configured dy-namically in the service process. The dynamic Abis functioncan provide wider bandwidth when the Abis transmission band-width is fixed.

22.Supports coding control.

Compared with GPRS, the measurement report of EDGE is im-proved a lot. The EDGE measurement is based on each pulse,that is, the measurement is performed according to the gran-ularity of Burst.

The fast measurement of EDGE makes the network respondto the radio environment change rapidly and select the mostproper coding mode to implement power control.

In downlink direction, iBSC supports selecting the coding modeby time slot and by TBF.



In uplink direction, iBSC selects the uplink TBF coding modeaccording to the uplink measurement parameters reported byBTS.

23. Supports retransmission.

In packet service, the negative feedback is employed to con-trol the retransmission. In other words, the transmitter findsout the packets not received correctly by the receiver accord-ing to the bitmap fed back from the receiver, then determineswhether to retransmit such packets.

In GPRS, the packet data is retransmitted in the coding modeoriginally transmitted. For example, the data block transmittedin CS4 mode is still retransmitted in CS4 mode.

In EDGE, two new retransmission methods are introduced:segmentation and reassembly; incremental redundancy.

24.Optimization of packet channel allocation algorithm.

iBSC supports multiple timeslots for MS. It allocates GPRS TBFor EDGE TBF to MS according to the GPRS/EDGE availability ofMS.

When iBSC allocates the PDTCH channel to MS, it selects thecarrier with lower load first. After selecting the carrier, it se-lects the most proper PDTCH channel combination in carriersaccording to the MS requirement.

25.Supports satellite Abis and satellite Gb.

There is a bidirectional time delay of about 540 ms in satellitetransmission, which impacts GPRS and EDGE services a lot.iBSC eliminates this impact as much as possible and ensuresthat GPRS and EDGE services run normally.

26.Supports various interfaces.

iBSC supports STM-1 interface, GE interface, and E1 interface.

27.Supports UMTS QoS.

After the GSM network evolves into GERAN, operators can pro-vide more powerful services for users thanks to the high-speedpacket data transmission brought by EDGE service. Suchservices include conversational service, stream media service,and interactive service. iBSC supports various service qualityrequirements of different services, i.e. QoS.

28. Supports extended uplink dynamic TBF.

Before the extended uplink dynamic allocation is applied inGPRS system, the number of uplink channels available for up-link TBF is always not more than the number of downlink chan-nels that are occupied simultaneously. iBSC supports the ex-tended uplink dynamic TBF and realizes that the number ofuplink channels is larger than the number of downlink chan-nels, satisfying the service requirement.

29. Supports multi-signaling-point connection.

According to the ITU-T specification, the maximum number ofsignaling links between two signaling points is 16, and the max-imum number of circuits is 4096. With the development of mo-bile network, the number of subscribers increases greatly, andthe maximum number of signaling links and circuits between


Chapter 1 Overview

offices defined in ITU-T specification can not satisfy the on-siteservice requirement.

iBSC adopts the unified 3G platform to support multi-signal-ing-point connection. In other words, one iBSC can connectmultiple MSCs.

30. Supports intelligent power-off.

When the system performance data reaches the thresholdvalue for power-on/off, iBSC sends message to notify BTS toperform the power-on/off operation.

iBSC can merge disperse timeslots within a certain time seg-ment to the minimum number of carriers, and make the un-used carrier power off to reduce power consumption. Duringtimeslot mergence, it prefers to merge timeslot to BCCH car-rier first.

iBSC supports customized intelligent power-off function at dif-ferent period, which can avoid network influence caused byenabling intelligent power-off during busy hour.

31. Supports TFO.

Tandem Free Operation (TFO) refers to the following process:After a call is established, the two TransCoders (TC) performin-band negotiation for the Codec used, to avoid unnecessaryvoice coding conversion at the sending end and the receivingend. TFO improves the voice quality and reduces the trans-mission delay.

32.Supports transparent channel.

The transparent channel implements transparent data trans-mission between a timeslot of E1 at one end's interface andthat at the other end's interface.

� If E1 cables at the two ends of the transparent channel arein the same shelf, this function is implemented by UIMUcircuit switching of the shelf.

� If E1 cables at the two ends of the transparent channelare in different shelves, this function is implemented bytransparent data forwarding through DSP (the DSP is usedto process user plane data).

iBSC supports the following transparent channels:

� The transparent channel between Abis interface and A-in-terface

� The transparent channel between Abis interface and Abisinterface

� The transparent channel between A-interface and A-inter-face

� The transparent channel between Abis interface and Aterinterface (if TC is remote)

33.Supports EGPRS and GPRS channel scheduling.

Take GPRS MS for example, the channel scheduling process isas follows:

Allocate the GPRS channel for GPRS MS first. If the EGPRSchannel is idle and the GPRS channel load is heavy, the GPRSMS can be allocated with EGPRS channel. If the EGPRS channel



load becomes heavy or the GPRS channel is idle, the GPRS MScan migrate to the GPRS channel.

34.Supports Dual Transfer Mode (DTM).

iBSC supports DTM. iBSC can perform CS/PS service simulta-neously under A/Gb mode.

35.Supports user tracing function.

iBSC implements signaling tracing for a single user accordingto the user's identification IMSI, TMSI, or TLLI.

36. Supports PS paging coordination

iBSC supports PS paging coordination, that is, under the packettransmission state, iBSC can make MS intercept the circuit pag-ing message.

37.Supports FLEX A.

FLEX A means one BSC can connect with multiple MSCs simul-taneously, and these MSCs form several MSC POOLs.

FLEX A networking is very flexible. Compared with traditionalMSC, the service provided by a MSC POOL has the followingadvantages:

� Expanding the service area of a MSC, reducing the fre-quency and flow of inter-MSC handover, position update,and HLR update.

� Improving the network equipment utilization. In a MSCPOOL, the VLR/MSC that a MS belongs to can be relativelyfixed. In this way, when the traffic suddenly increases ina hotspot area, the load of a certain MSC will not increasewith it.

� Increasing the disaster recovery capability of the entire net-work. When a MSC fails in the MSC POOL, its traffic will betransferred to other MSCs in the area.

FLEX A networking is transparent to MS, that is, MS is notinvolved in the changing of networking mode.

38.Supports FLEX Gb.

FLEX Gb means one BSC can connect with multiple SGSNs si-multaneously, and these SGSNs form several SGSN POOLs.

FLEX Gb networking is very flexible, compared with traditionalMSC, the service provided by a SGSN POOL has the followingadvantages:

� Expanding the service area of a SGSN, reducing the fre-quency and flow of inter-SGSN PS handover, routing areaupdate, and HLR update.

� Improving the network equipment utilization. In a SGSNPOOL, the VLR/SGSN that a MS belongs to can be relativelyfixed. In this way, when the traffic suddenly increases in ahotspot area, the load of a certain SGSN will not increasewith it.

� Increasing the disaster recovery capability of the entire net-work. When a SGSN fails in the SGSN POOL, its traffic willbe transferred to other SGSNs in the area.


Chapter 1 Overview

FLEX Gb networking is transparent to MS, that is, MS is notinvolved in the changing of networking mode.

39.Supports preemption and queuing for packet service.

Preemption of packet service means that all dynamic and staticpacket channels are considered while assigning packet radioresource according to user's QoS requirement. If the idle radioresource on the channel can not meet the QoS requirement orthe number of users on the channel reaches the upper limit, insuch cases, if the current user can do preemption, BSC will re-lease the radio resource of one or more users with low priorityto the current service.

Queuing of packet service means that, when BSC can not getsufficient packet radio resource according to user's QoS re-quirement, the system will do its best to assign packet radioresource to make the service access, and then queue to waitfor radio resource that can meet the user's QoS requirement.

If BSC supports both preemption and queuing, the system doespreemption of packet service first; if the preemption fails, thesystem performs queuing.

40.Supports external Network Assisted Cell Change (NACC).

The external NACC can increase the access speed in new cellwhile doing MS reselection towards external cell, shorten thecell reselection time during MS data transmission, and increasedata transmission rate.

41. Supports network-controlled cell reselection

Network-controlled cell reselection means that, after BSC re-ceives the measurement report from MS, it stores the mea-sured level value in service cell and adjacent cell, performsweighted average processing, and makes cell reselection deci-sions based on processing results and network service loads.

Network-controlled cell reselection can fully use the networkinformation to make appropriate decision and implement op-timized service allocation in the network. Meanwhile, it canavoid useless cell reselection made by MS to increase the TBFdata transmission efficiency.

42.Supports uplink incremental redundancy.

Incremental redundancy is one of the link quality controlmodes of EDGE. Under the uplink incremental redundancymode, when BTS successfully decodes RLC header but fails todecode a data block, BTS stores the data block not decodedand notifies MS. MS uses another perforation mode to codethe data block and retransmits it, BTS can independentlydecode the retransmitted data block; if BTS fails to decodethe block, it can perform joint decoding by combining thedata blocks that fail to be decoded before. Because datablocks coded in different perforation modes include differentredundant information, combining these blocks will increasethe redundant information, thus the probability of decodingsuccess increases.

43.Supports ZXSDR BS8800 GU360.

ZXSDR BS8800 GU360 is the new generation product of indoormacro base station. It uses the multi-carrier technology, with



an architecture in which baseband and RF are separated, im-plementing GSM/WCDMA dual-mode.

44.Supports multiple network numbers.

iBSC supports sharing radio network among different opera-tors, that is, different operators can configure respective cellsat the same site. In this way, multiple operators can accessthe network simultaneously.

45.Supports voice noise suppression and level control.

The noise suppression function can improve the voice Signal toNoise Ratio (SNR) and voice quality.

The level control function can optimize signal level to improvethe communication quality.

The TFO function is mutually exclusive with noise suppressionand level control, that is, once TFO is established, there is noneed to activate the noise suppression function and level con-trol function.

46. Supports high-order multiple timeslot capability for PS ser-vice.

iBSC supports the high-level multiple timeslot capability for PSservice. The downlink of single service can be assigned with 5timeslots at most for data transmission, causing the downlinkrate to increase to 296 Kbps. Higher transmission rate willimprove the quality of FTP file transferring service and mailservice.

47.Supports IP transmission mode at A-interface.

With the evolution of network technology, the IP-based trans-mission resource is easier to obtain. Compared with traditionalcircuit network, the utilization of IP network becomes muchhigher and the networking mode is more flexible.

iBSC supports IP bearer through A-interface, which helps thenetwork to develop towards the all-IP trend. It enables easiermerging between GSM network and future transmission net-work.

iBSC supports IP transmission mode at A-interface only whenthe hardware uses gigabyte platform. If the hardware usesmegabyte platform, the IP transmission mode at A-interface isnot supported.


Chapter2 System Indices


>> Physical Indices>> Power Supply Indices>> Environmental Requirements>> Clock Indices>> Reliability Indices>> Interface Types>> Capacity Indices

2.1 Physical Indices

2.1.1 Dimensions

� Excluding left and right side doors: H × W × D = 2000 mm ×600 mm × 800 mm

� Including left and right side doors: H × W × D = 2000 mm ×650 mm × 800 mm

Note:

Outline dimension for the whole cabinet: 2000 mm × 600 mm ×800 mm (H × W × D), the width of a single side panel is 25 mm.

2.1.2 Overall Weight

The weight of full configuration one rack is less than 270Kg (withbuilt-in PCU and TC).

The weight of full configuration two rack is less than 540Kg (withbuilt-in PCU and TC).



2.2 Power Supply Indices

2.2.1 Power Supply Range

Power Requirement for the primary DC by ZXG10 iBSC:

� The nominal value of voltage provided by the power equipmentin the equipment room is -48V, with an acceptable range from-57V to -40V.

� The noise level in the power voltage should be in compliancewith the general technical specifications of the former MPT.

� Power supply has over-current protection and indication.

� Grounding resistance: <1 ohmer

2.2.2 Power Consumption

The power consumption of ZXG10 All IP Enhance iBSC rack is basedon the calculation according to the actual configuration:

� One rack configuration

For all E1 interface, the power consumption is 2558W; For allIP interface, the power consumption is 2542W(including 160Wpower consumption of SCBX, with built-in PCU and TC).

� Two racks configuration

For all E1 interface ,the power consumption is 6368W;For allIP interface, the power consumption is 3808W(including 160Wpower consumption of SCBX, with built-in PCU and TC)

2.3 Environmental Requirements

2.3.1 Grounding Requirement

1. Grounding mode

The iBSC cabinet can be upper-grounded or lower-grounded.

2. Grounding resistance

� Cabinet grounding resistance: 0.1 Ω ~ 0.3 Ω

� Equipment room grounding resistance: 1 Ω


Chapter 2 System Indices

2.3.2 Temperature and HumidityRequirement

1. Operating temperature

� Long-term operating temperature: 0˚C ~ 40˚C

� Short-term operating temperature: -5˚C ~ 45˚C

2. Relative humidity

� Relative humidity for long-term operation: 20% ~ 90%

� Relative humidity for short-term operation: 5% ~ 95%

Note:

In the equipment room, the temperature and humidity are mea-sured in the following condition: there is no protection panels infront of and behind the cabinet; 1.5 m above the ground and 0.4m in front of the cabinet. The short-term operation does not ex-ceed 48 continuous hours and does not exceed 15 days per year.

2.3.3 Air Quality Requirement

1. Air inside the equipment room must be free of magneto-con-ductive, conductive, and corrosive gases that may corrodemetallic parts and degrade insulation.

2. Density of dust particles with a diameter larger than 5 µm≤3×104 grains/m3

2.3.4 Barometric Requirement

Air pressure: 70 kPa ~ 106 kPa

2.4 Clock IndicesTable 1 lists clock indices of iBSC.

TABLE 1 IBSC CLOCK INDICES

Index Value

Clock level Level–3 class-A clock

Minimum clock accuracy ±4.6×10-6



Index Value

Pull-in range ±4.6×10-6

Maximum frequency deviation 2×10-8/day

Maximum initial frequency deviation 1×10-8

Clock working mode Fast pull-in, trace, hold, andfree run

Clock synchronization modeExternal clock synchroniza-tion; extracting from the lineclock

2MBITS 2

2 MHz 2Clock synchronizationinterfaces

Line 8 kbps 2

2.5 Reliability Indices� Mean Time Between Failure (MTBF) ≥ 100,000 hours

� Mean Time To Repair (MTTR) ≤ 30 minutes

� System restart time < 10 minutes

2.6 Interface TypesTable 2 and Table 3 list interface types of iBSC.

TABLE 2 IBSC INTERFACE TYPES (1)

Transmission TypeA-Interface

(Connecting MSC)(TC Is Internal)

Ater Interface(Connecting iTC)(TC Is External)

STM-1 √ √

GE √ ×

E1 √ √

T1 × ×

IPoE × ×


Chapter 2 System Indices

TABLE 3 IBSC INTERFACE TYPES (2)

TransmissionType

Abis Interface(Connecting

BTS)

Gb Interface(ConnectingSGSN)

OMC Interface

STM-1 √ × ×

GE √ √ √

E1 √ √ ×

T1 √ × ×

IPoE √ × ×

2.7 Capacity Indices1. Table 4 lists the maximum capacity of A-interface and Abis in-

terface.

TABLE 4 CAPACITY OF A-INTERFACE AND ABIS INTERFACE FOR FULL-CONFIGURED SYSTEM

A-Interface E1(T1) A STM-1 A IP A

Abis In-terface

Cabinet Num-ber ofcarriers

InterfaceCapabil-ity

Num-ber ofcarriers

InterfaceCapability

Num-ber ofcar-riers

InterfaceCapability

Abis:208E1(T1)

Abis:208E1(T1)

Abis:208E1(T1)Single

Cabinet 1024A:188E1(T1)

1024

A:4STM-1

1024

A:1GE

Abis:624E1(T1)

Abis:624E1(T1)

Abis:624E1(T1)

E1(T1)Abis

DualCabinets 3072

A:700E1(T1)

3072

A:11STM-1

3072

A:2GE

Abis:3STM-1

Abis:3STM-1 Abis:3STM-1

SingleCabinet 1024

A:188E1(T1)

1024

A:4STM-1

1024

A:1GE

DualCabinets

Abis:9STM-1

Abis:9STM-1 Abis:9STM-1

STM_1Abis

3072A:700E1(T1)

1024

A:11STM-1

3072

A:2GE



A-Interface E1(T1) A STM-1 A IP A

Abis In-terface

Cabinet Num-ber ofcarriers

InterfaceCapabil-ity

Num-ber ofcarriers

InterfaceCapability

Num-ber ofcar-riers

InterfaceCapability

Abis:1GE Abis:1GE Abis:1GESingleCabinet 1024

A:252E1(T1)

1024A:4STM-1

2048A:1GE

DualCabinets Abis :2GE Abis:2GE Abis:2GE

IP Abis

3072A:700E1(T1)

3072

A:11STM-1

3072

A:2GE

Abis:160E1(T1)

Abis:160E1(T1)

Abis:160E1(T1)Single

Cabinet 1024A:188E1(T1)

1024

A:4STM-1

1024

A:1GE

DualCabinets

Abis:480E1(T1)

Abis:480E1(T1)

Abis:480E1(T1)

IPoE AbisEIPI+D-TB

3072A:700E1(T1)

3072

A:11STM-1

3072

A:2GE

\ Abis:3STM-1 Abis:3STM-1

SingleCabinet \

\

1024

A:4STM-1

1024

A:1GE

\ 9STM-1 Abis:9STM-1

IPoE AbisEIPI+S-DTB2

DualCabinets \

\3072

11STM-13072

A:2GE

2. Maximum capacity of Gb interface

Two Rack with all IP Two Rack with TDM

600M 256M

3. Maximum capacity of TRX, Site, Erl, BHCA

MaximumTRX

MaximumSite Maximum Erl BHCA

3072 1536

15000Erl(b-ased on thetraffic modelof ZTE)

4200k


Chapter3 Hardware Structure


>> Cabinet Layout>> Shelves>> Boards>> Shelf Configuration and Principle>> Equipment Configuration

3.1 Cabinet LayoutFigure 3 illustrates the internal layout of iBSC cabinet.

FIGURE 3 CABINET LAYOUT SCHEMATIC DIAGRAM

1. Power distribution subrack2. Fan subrack3. Dustproof subrack



3.2 ShelvesPhysically, iBSC system has three types of shelf: control shelf, re-source shelf, and packet switching shelf. The functional descriptionof each shelf is given in Table 5.

TABLE 5 SHELF DESCRIPTION

Shelf Type Functions

Control shelf(BCTC)

In BCTC, there are centralized all criticalcontrol module, including OMP (Operation andMaintenance Main Processor) which is used forcontrolling and managing whole BSC system,CMP (Control Main Processor) is used for serviceimplementing and call controlling. The entiresystem synchronization is maintained by CLKG(CLOCK Generator) or ICM (with GPS receiver),and CHUB (Control HUB) provides central hubfunction to collect signalling from individualBGSN.

Resource shelf(BGSN)

BGSN is made up with AIU, BIU, PCU, and TCU,for interface accessing and user plane dataprocessing.

Packet switchingshelf (BPSN)

BPSN provide a powerful IP based switchingnetwork which supports higher capacity for iBSC.The key switch board PSN can provide 40Gbpsfor packet switching.

3.3 BoardsThe boards are configured in the shelves. They are classified intofront board and rear board according to the assembly relation. Thefront board and rear board are inserted in the slot on the back-plane. The indicators for board running status are installed on thefront board panel. The rear board assists the front board to leadout the external signal interface (the optical fiber is led out fromfront board panel) and the debugging port to implement the con-nection between different shelves in the same cabinet, betweendifferent cabinets, and between the system and external NEs.

Table 6 describes the boards of iBSC.

TABLE 6 IBSC BOARD LIST

Board Name Functions BoardFunctionName

Correspond-ing RearBoard

IPBB

IPAB

IPGB

GIPI Provides GEinterface foriBSC system.Each GIPIboard provides1 gigabyte

RGER


Chapter 3 Hardware Structure



externalelectricalinterfaceor opticalinterface, and1 internaluser-planegigabyteelectricalinterface.

IPI

IPBB

IPAB

BIPI Provides FEinterface foriBSC system.Each BIPIprovides 4 FEinterfaces.

IPGB

RMNIC

EIPI Provides IPaccess for E1.

EIPI -

RCHB1CHUB CHUB andUIMC/UIMUwork togetherto control theexchange andconvergenceof the systeminternalcontrol–planedata.

CHUB

RCHB2

RCKG1CLKG Implements theclock functionof iBSC system.

CLKG

RCKG2

RCKG1ICM Performs theclock functionof iBSC system,and has the GPStransceiver.

ICM

RCKG2

CMP Implementsthe servicecall controlmanagementin PS/CSdomain, andthe resourcemanagementfor the systemand sub-layerssuch as BSSAPand BSSGP.

CMP -

DTB Each DTBprovides 32 E1interfaces.

DTB RDTB





GLI Providesinterfaces andprocessingfunctions forinterconnectingresourceshelves.

GLI -

BIPB2

AIPB

DRTB2

UPPB2

GUP2 Implementscodeconversion,TDM packageand IP packageconversion,user planeprotocolprocessing,RTP protocolprocessingand packagingfunction.

TIPB2

-

BIPB

DRTB

GUP ImplementsAbis interfaceprocessing,transcoding,and rateadaptation.

TIPB

-

UPPB Implementsuser-planeserviceprocessing.

UPPB -

OMP Implements thesystem globalprocessing,provides anexternal FEinterface toconnect theoperation &maintenancesystem; directlyor indirectlymonitors andmanagesboards in thesystem.

OMP RMPB

PSN Implements theexchange oflarge-capacityuser-plane datawith .

PSN -

SDTB2 Provide 2STM-1 standardinterfaces with155 M capacity

SDTB2 RGIM1





SDTB Provides astandard 155M STM-1interface.

SDTB RGIM1

SPB2

GIPB2

SPB2 Implementssignalingprocessingfunction andexternal E1interfacefunction

LAPD2

RSPB

SPB

GIPB

SPB Implementssignalprocessingfunction andexternalinterfacefunction.

LAPD

RSPB

SBCX Stores somefiles neededby OMP, andorganizesthese filesaccording tothe requirementof operation &maintenancesystem.

SBCX RSVB

RUIM2UIMC Provides aswitchingplatform forcontrol shelfand packetswitching shelf.

UIMC

RUIM3

RGUM1GUIM Providesan internalplatform forresource shelf.

GUIM

RGUM2

UIMU Providesan internalplatform forresource shelf.

UIMU RUIM1



Note:

Each board has two names: board hardware name and board func-tion name. The board hardware name is the board identificationwhile the board function name reflects the function that the boardimplements after software is loaded. The same hardware boardcan implement different functions by loading different software.

3.4 Shelf Configuration andPrinciple

3.4.1 Control Shelf (BCTC)

3.4.1.1 Configuration

Table 7 explains the boards that can be configured in control shelf.

TABLE 7 BOARDS IN CONTROL SHELF

Board Rear Board Backplane

OMP MPB rear board(RMPB)

CMP -

UIM rear board 2(RUIM2)

UIMC


CHUB rear board 1(RCHB1)

CHUB

CHUB rear board 2(RCHB2)

CLKG rear board 1(RCKG1)

ICM

CLKG rear board 2(RCKG2)

SBCX SBCX rear board(RSVB) BCTC

Figure 4 shows the full configuration of control shelf.



FIGURE 4 FULL CONFIGURATION OF CONTROL SHELF

Configuration of boards in the control shelf is as follows:

� OMP boards (2, active and standby) are inserted in slots 11and 12, which are mandatory.

� CMP boards (2 ~ 4, active and standby) can be inserted in slots1 ~ 4. The number of CMP boards to be configured dependson the configuration capacity.

Note:

If capacity expansion is required for the processing perfor-mance, the CMP board can also be inserted in other shelves.It is recommended to insert the CMP board in BPSN shelf.

� SBCX boards (2, active and standby) are inserted in slots 5and 7.

� ICM boards (2, active and standby) are inserted in slots 13 and14, which are mandatory.

� CHUB boards (2, active and standby) are inserted in slots 15and 16, which are mandatory.

� UIMC boards (2, active and standby) are inserted in slots 9 and10, which are mandatory.

� RUIM2 board (1) is inserted in slot 9 fixedly, which is manda-tory.

� RUIM3 board (1) is inserted in slot 10 fixedly, which is manda-tory.

� RMPB boards (2) are inserted in slots 11 and 12 fixedly, whichare mandatory.

� RCKG1 board (1) is inserted in slot 13 fixedly.

� RCKG2 board (1) is inserted in slot 14 fixedly.

� RCHB1 board (1) is inserted in slot 15 fixedly.



� RCHB2 board (1) is inserted in slot 16 fixedly.

� RSVB boards (2) are inserted in slots 5 and 7 fixedly.

� RBID board (1) is configured in BCTC shelf.

3.4.1.2 Principle

Figure 5 shows the principle of the control shelf.

FIGURE 5 PRINCIPLE OF CONTROL SHELF

1. Inter-shelf communication function

� iBSC supports to configure a pair of ICM boards. Usu-ally, ICM is configured on the control shelf. The systemclock is distributed to switching shelves and gigabit re-source shelves via the cable.

� The network port OMC2 of the rear board of OMP and thenetwork port OMP1 of the rear board of SBCX are connectedthrough HUB. The network port OMC1 of the rear board ofSBCX is connected with external network through anotherHUB, realizing separation of internal network segment andexternal network segment. OMM is installed on the SBCXboard.

� CHUB is the center where the control flows of the switch-ing shelf, the gigabit resource shelf, and the control shelfgather.

2. Intra-shelf communication function



� BCTC backplane bears signaling processing board and MSmodules. It gathers and processes the control plane dataforming a distributed processing platform in the multi-shelfsystem.

� UIMC is the signaling switching center of the control shelf,implementing the information switching between modules.

� OMP board is responsible for the global processing and con-trols O&M of the whole system (including O&M agent).

OMP board is the core of iBSC OMC. It directly or indirectlymonitors and manages the boards. OMP board uses Ether-net and RS485 to configure and manage the boards.

� SBCX not only functions as OMM server but also saves somefiles needed by OMP, and it organizes these files accordingto the form required by OMM.

� CMP board is connected with the switching unit of controlplane, implementing all the protocol processing on controlplane.

3.4.2 Switch Shelf (BPSN)


Table 8 explains the boards that can be configured in packetswitching shelf.

TABLE 8 BOARDS IN PACKET SWITCHING SHELF

Board Rear board Backplane

PSN -

GLI -

CMP -


UIMCUIM rear board 3(RUIM3) BPSN

Figure 6 shows the full configuration of packet switching shelf.



FIGURE 6 FULL CONFIGURATION OF PACKET SWITCHING SHELF

1. Packet switching shelf provides Level-1 IP switching platformfor the iBSC system. It can either expand the user plane formultiple resource shelves or provide external high-speed in-terfaces directly. Each pair of GLIs provides eight pairs of ac-tive/standby optical interfaces. Thus three pairs of GLIs pro-vide 24 pairs of optical interfaces to interconnect with the 24pairs of active/standby optical interfaces of GUIMs of the sixgigabit resource shelves. Each GUIM board fixedly uses twopairs of optical interfaces.

2. Configuration of boards in the packet switching shelf is as fol-lows:

� UIMC (2, active and standby) boards implement Level-1switching. They are inserted in slots 15 and 16, which aremandatory.

� PSN boards (2, load sharing) implement data switching be-tween line cards. They are inserted in slots 7 and 8, whichare mandatory.

� GLI boards (2 ~ 6, load sharing) implement GE line in-terface function. They can be inserted in slots 1 ~ 6. Thenumber of GLI boards to be configured depends on the con-figuration capacity. GLI boards must be configured in pairs,and are added from the left to the right.

� CMP board (0 ~ 2, active and standby) can be inserted inslots 11 ~ 14. One pair of CMP boards is configured forevery 1024 carriers.

� RUIM2 board (1) is inserted in slot 15, which are manda-tory.

� RUIM3 board (1) is inserted in slot 16, which are manda-tory.

� RBID board (1) is configured in BPSN shelf.



3.4.2.2 Principle

Figure 7 shows principle of the packet switching shelf.

FIGURE 7 PRINCIPLE OF PACKET SWITCHING SHELF

1. Inter-shelf communication functions

� All resource shelves connect with GLI on the switching shelfvia the optical interface on the front panel of GUIM.

� The control shelf connects with UIMC on the switching shelfvia RCHB1 and RCHB2 (rear board of CHUB).

� Clock signals connect with UIMC on the switching shelf viaRCKG1 and RCKG2 (rear board of ICM).

2. Intra-shelf communication functions

i. User plane data

– The packet switching shelf accesses the user plane datathrough GLI and performs relevant processing.

– The data is sent to PSN through the high-speed signalcable of the backplane for switching.

– GLI receives the switched data from PSN for processing.

– At last, the data is sent to the destination interface.

ii. Control plane data

UIMC switching uses the Ethernet bus as the internal con-trol bus of the subsystem, connecting all modules in thesubsystem, distributing and collecting route information,maintaining and managing system configurations, and re-alizing upper-level protocol and signaling data transmis-sion.



3.4.3 Resource Shelf (BGSN)


Table 9 explains the boards that can be configured in gigabit re-source shelf.

TABLE 9 BOARDS IN GIGABIT RESOURCE SHELF

Board Rear Board Backplane

DTB RDTB

SDTB2 RGIM1

GUIM rear board 1(RGUM1)

GUIMGUIM rear board 2(RGUM2)

GUP2 -

GIPI RGER

SPB2 RSPB

EIPI - BGSN

Gigabit resource shelf can be configured in many ways. The follow-ing is an example of gigabit resource shelf configuration, in whichAbis interface adopts E1 or IPOE, A-interface adopts E1, and Gbinterface adopts E1, as shown in Figure 8.

FIGURE 8 AN EXAMPLE OF GIGABIT RESOURCE SHELF CONFIGURATION



Configuration of boards in the gigabit resource shelf is describedas follows:

� GUIM boards (2, active and standby) are inserted in slots 9and 10, which are mandatory. They lead out multi-mode fiberconnecting level-1 switching.

� DTB boards can be configured in any slot except the slots 9,10, 15 and 16. DTB boards can not be configured in more than3 consecutive slots. It is advised not to configure DTB in slots1 and 17. It is recommended to configure six DTBs in eachshelf, and the maximum number of DTBs configured in eachshelf is not more than eight.

� SDTB2 boards (active-standby configuration) can be config-ured in any slot except slots 9, 10, and 17. The SDTB2 panelleads out two pairs of single-mode fiber. If the SDTB2 boardis of non-active-standby configuration, when SDTB2 board isconfigured in active or standby slot, the adjacent active andstandby slots must not be configured with boards that use HWcables, such as DTB, GUP2, SPB2, and EIPI.

� GUP2 can be configured in any slot except slots 9, 10, 1, and17.

� SPB2 can be configured in any slot except slots 9 and 10. Slot15 and slot 16 can not be configured with SPB2 at the sametime.

� GIPI can be configured in any slot except slots 9 and 10. Slot15 and slot 16 can not be configured with GIPI at the sametime. The panel has a gigabit optical interface; when config-ured with RGER, the panel has a gigabit electrical interface;when configured with RMNIC, the panel has four megabit elec-trical interfaces (active-standby configuration).

GIPI board is used to provide OMCB channel. It can be config-ured in slots 5 ~ 8, 13, and 14 when being used to connect MRserver (GIPI is of active-standby configuration). In such cases,the GIPI board provides four FEs both internally and externally,the corresponding rear board is RMNIC.

� EIPI board can be configured in any slot except slots 9 and 10.Slot 15 and slot 16 can not be configured with EIPI at the sametime.

� For SDTB2, SPB2, GIPI, EIPI, and GUP2 board, if the board isconfigured in slot 15 or 16, the TDM board can not extract theline 8 K clock reference, and the serial port of slot 16 can notbe used.

� RGUM1 board (1) and RGUM2 board (1) are inserted in slots 9and 10, which are mandatory.

� RDTB, RSPB, and RGER/RMNIC board are configured corre-sponding to each front board.

� The SDTB2 rear board (RGIM1) is used to extract STM-1 line8 K clock. Thus when it is not required to extract the lineclock, SDTB2 is not configured. Usually, when the number ofconfigured SDTB2 is more than one, two RGIM1s should beconfigured, and two clock extracting cables are also required.

� RBID board (1) is configured in BGSN shelf.



3.4.3.2 Principle

Figure 9 shows the principle of the gigabit resource shelf.

FIGURE 9 PRINCIPLE OF GIGABIT RESOURCE SHELF

1. Inter-shelf communication function

� GUIM provides the control Ethernet channel to connect ex-ternal gigabit resource shelves. GUIM connects with CHUB(the gathering center of the control flows from the controlshelves).

GUIM interconnects with GLI of the packet switching shelf,implementing Level-1 switching between different resourceboards.

� DTB and SPB2 provide the interface for E1 line.

� SDTB2 provides STM-1 access.

� GIPI provides FE/GE access.

� EIPI provides E1/T1-based IP access, and works with DTBor SDTB2.

� The gigabit resource shelf gets system clock from ICM ofthe control shelf through cables.

2. Intra-shelf communication function

� BGSN is the backplane of the gigabit resource shelf. Mul-tiple service processing modules can be inserted, formingthe common service processing subsystem.

� GUIM is the gathering and switching center of various dataof gigabit resource shelf, implementing the information ex-change between modules.

� GUP2 implements user-plane-related radio protocol pro-cessing, TC code transformation, rate adaptation and con-version from TDM to IP packet.

� GIPI provides one gigabit electrical interface or fourmegabit interfaces through the backplane for the internaluser plane.



3.4.4 Connection Between Shelves

In iBSC, internal connections involve the following types of cables:

� Clock distribution cable and line clock extracting cable

� Control plane Ethernet cable

� User plane fiber

� Monitoring cable

3.4.4.1 Clock Extracting and Distribution

Figure 10 shows the clock extracting and distribution inside a sin-gle cabinet.

FIGURE 10 SINGLE CABINET CLOCK EXTRACTING AND DISTRIBUTION

Figure 11 shows the clock extracting and distribution inside dualcabinets.



FIGURE 11 DUAL-CABINET CLOCK EXTRACTING AND DISTRIBUTION

� Clock reference

The ICM board can get the BITS clock reference or obtain theclock reference from GPS module.

� Clock distribution

The rear boards (RCKG1, RCKG2) of ICM board are connectedwith GUIM/UIMC board of each shelf through the clock cable,and GUIM/UIMC distributes the clock signals to slots of eachshelf.

3.4.4.2 Control Plane Ethernet Connections

Figure 12 shows the control plane connections inside a single cab-inet.

FIGURE 12 SINGLE CABINET CONTROL PLANE ETHERNET CONNECTIONS

In Figure 12, the real line represents the cable connection whilethe broken line represents the backplane printed cable connection.



The iBSC system control plane Ethernet interconnection is realizedthrough CHUB board.

� GUIM in the gigabit resource shelf or UIMC in the packet switch-ing shelf is connected with CHUB board through Ethernet cable.

� UIMC in the control shelf is connected CHUB board through thebackplane printed cable.

Figure 13 shows the control plane connections inside dual cabinets.

FIGURE 13 DUAL-CABINET CONTROL PLANE ETHERNET CONNECTIONS

In Figure 13, the real line represents the cable connection whilethe broken line represents the backplane printed cable connection.

The iBSC dual-cabinet control plane Ethernet interconnection isrealized as follows:

� Connect UIMC/GUIM boards in all shelves except the controlshelf in cabinet 1 with CHUB boards through the cables.

� Connect UIMC board in the control shelf in cabinet 1 with CHUBboard through the backplane printed cable.

3.4.4.3 User Plane Connections

Figure 14 shows the user plane connections inside a single cabinet.



FIGURE 14 SINGLE CABINET USER PLANE CONNECTIONS

Fiber optic cables are used for the connections between GLI andGUIMs in the gigabit resource shelf.

Figure 15 shows the user plane connections inside dual cabinets.

FIGURE 15 DUAL-CABINET USER PLANE CONNECTIONS

3.4.4.4 Monitoring Circuit Connections

Figure 16 shows the monitoring cable connections inside a singlecabinet.



FIGURE 16 SINGLE CABINET MONITORING CABLE CONNECTIONS

The fan plug-in box and the cabinet-top fan are connected withthe power distribution plug-in box through cables, realizing themonitoring of fans.

The OMP board is connected with the PWRD board in power plug-inbox, realizing the monitoring of PWRD board.

Sensors are connected with the power distribution plug-in box,realizing the monitoring of the external environment.

Figure 17 shows the monitoring cable connections inside dual cab-inets.



FIGURE 17 DUAL-CABINET MONITORING CABLE CONNECTIONS

The fan plug-in box and the cabinet-top fan are connected with thepower distribution plug-in box in the same cabinet through cables,realizing the monitoring of fans.

The OMP board in cabinet 1 is connected with the PWRD boardin the same cabinet while the PWRD board in cabinet 2 is con-nected with the PWRD board in cabinet 1, realizing the monitoringof PWRD boards in cabinet 1 and 2.

Sensors are connected with the power distribution plug-in box incabinet 1, realizing the monitoring of the external environment.

3.5 Equipment ConfigurationConfiguration

Principle1. The resource shelf contains AIU, BIU, TCU, and PCU, and

boards include DTB, SDTB/SDTB2, GUP/GUP2, UIMU/GUIM,GIPI, and EIPI. When the system is expanded, the capacitycan be expanded by adding resource shelf to configure moreboards.

2. Boards of the control shelf includes CMP, SBCX, UIMC, OMP,CLKG, and CHUB.

3. Boards of the packet switching shelf includes GLI, PSN, CMP,and UIMC.

TypicalConfigurations

Figure 18 shows the configuration when both Abis interface andA-interface adopt E1 transmission mode



FIGURE 18 CONFIGURATION (ABIS INTERFACE: E1, A-INTERFACE: E1)

Figure 19 shows the configuration when both Abis interface andA-interface adopt IP connection mode.



FIGURE 19 CONFIGURATION (ABIS INTERFACE: IP, A-INTERFACE: IP)

Figure 19 shows the configuration when Abis interface adopt IPoEand A-interface adopt IP connection mode.



FIGURE 20 CONFIGURATION (ABIS INTERFACE: IPOE, A-INTERFACE: IP)



This page is intentionally blank.


Chapter4 Software Structure


>> Foreground Software>> Background Software

4.1 Foreground SoftwareThe foreground software structure of iBSC is shown in Figure 21

FIGURE 21 IBSC FOREGROUND SOFTWARE STRUCTURE

The foreground software includes:

1. BSP&Driver

BSP subsystem offers driver for hardware, screen hardwarefunction and mapping of logical functions to upper software.

2. Operation Support Subsystem (OSS)

Operation Supporting System, which works between BSP andother subsystem. Task of OSS includes process communica-tion, file management, equipment driving, schedule work, etc.

3. Bearer Subsystem (BRS)

Bearer subsystem works based on OSS to offer ATM, IP, TDMbearer services for service subsystem, ignalling subsystem,



O&M subsystem. The function of BRS can be divided as linklayer function, network transmission function, dynamic routerfunction, ATM function, flux-controlling function.

4. Primary Peripheral subsystem (PP)

PP subsystem mainly has five functions: digital interface man-agement, switch network management, offering system clock,monitoring environment and power management.

5. System Control Subsystem (SCS)

System Control subsystem, works on OSS and Database sub-system, responsible for monitoring whole system, downloadingsoftware and upgrading system.

6. Database Subsystem (DBS)

Database Subsystem, which works on OSS subsystem, respon-sible for management of network element and information ofservices, signalling, protocol.

7. Operation & Maintenance Subsystem (OMS)

OMS is a foreground implementation of the operation & main-tenance system. It performs the following functions:

� Performance management

� Signal tracing

� Fault management

� Dynamic data observation

8. Signaling subsystem (SS)

Signaling subsystem works above OSS, DBS, and bearersubsystem. It implements the narrow band No. 7 signaling,broadband No. 7 signaling, calling signaling, IP signaling andgateway control signaling. It also provides services for RANCand RANSS.

9. RAN Control Plane Subsystem (RANC)

RANC performs the following functions:

� Implements processing of layer-3 control plane protocolsat Um, Abis, A, and Gb interface.

� Implements calling signaling connection control, including;radio resource management, dynamic channel resource ad-justment, load control, acceptance control, handover deci-sion, and signaling connection management.

10.RAN User Plane Subsystem (RANU)

RANU performs the following functions:

� For PS service, it provides data forwarding and schedulingat radio interface and Gb interface according to the QoSdemand.

� For CS service, it provides the TC function of GUP board.

11.RAN Service Support Subsystem (RANSS)

RANSS provides support for control plane and user plane sub-systems. It performs the following functions:

� Guarantees the proper process of services.


Chapter 4 Software Structure

� Performs monitoring of various services.

� Implements iBSC global processes, including signalingtracing, load control, acceptance control, and performancemeasurement.

12.Micro-Code subsystem (MSC)

Micro-Code subsystem, the main function is to quickly deal withuser plane’s data, to realize separation between user plane andcontrol plane.

4.2 Background SoftwareThe background software runs at the network management sys-tem server and client. It is called NetNumen (TM) M31, commu-nicating with iBSC by TCP/IP protocol. NetNumen (TM) M31 per-forms the following functions:

� Configuration management



� System management

� Log management

� Version management

� Topology management

� Security management


Chapter5 System Principle


>> Logic Units>> User Plane Data Flow>> Control Plane Signal Flow

5.1 Logic UnitsFigure 22 shows the hardware system structure of iBSC.

FIGURE 22 HARDWARE SYSTEM DIAGRAM OF IBSC

Logically, iBSC consists of six units:

1. Access unit

This unit provides the following interface access processing foriBSC:

� A-interface/Ater interface

� Abis interface

� Gb interface

This unit includes:

� A-Interface Unit (AIU) (when TC is external, AIU belongsto iTC system, and the Ater interface unit NSMU is addedbetween iBSC and iTC)

� Abis Interface Unit (BIU)



� Gb Interface Unit (GIU)

2. Switching unit

This unit provides a large-capacity platform without conges-tion.

3. Processing unit

This unit performs upper-level protocol processing for systemcontrol plane.

4. User plane Processing unit

This unit performs user plane protocol processing in PS domain.

5. O&M unit

This unit performs management for iBSC system, and providesglobal configuration data storage and OMC interfaces.

6. Peripheral device monitoring unit

This unit performs detecting and alarm for iBSC cabinet powerand environment, and detecting and controlling for the cabinetfan.

7. TC unit

This unit performs transcoding and rate adaptation. When TCis external, this part's function is implemented by iTC.

5.1.1 O&M Unit

The O&M unit contains OMP and SBCX.

� The OMP board is responsible for handling global processes andO&M for the entire system. It is connected with OMC-R through100 Mbps Ethernet. As the core of O&M of iBSC, the OMP boarddirectly or indirectly monitors and manages the boards in thesystem.

� The SBCX board is used for saving some files needed by OMP,and organizes these files according to the format requirementof OMC-R.

Figure 23 shows the connection relationship between the O&M unitand OMC-R.

FIGURE 23 COMMUNICATION BETWEEN O&M UNIT AND OMC-R


Chapter 5 System Principle

5.1.2 Processing Unit

The processing unit is just the CMP Board in iBSC. It performs thefollow functions:

� PS/CS service and call control and management

� BSSAP, BSSGP and system resource management

5.1.3 BIU

In iBSC, Abis interface has three types: E1, IP, and IPoE.

E1 Abis The hardware structure of E1 Abis interface unit is shown in Figure24.

FIGURE 24 E1 INTERFACE BIU HARDWARE STRUCTURE

E1 interface BIU consists of DTB board, GUP board, and SPB board.

1. DTP implements E1 access.

2. The LAPD signaling from BTS is switched to SPB through UIMUboard in the current resource shelf, and SPB performs the LAPDprocessing.

3. CS service and PS service are switched to GUP board throughUIMU board in the current resource shelf, search the 20 ms TRUframe (or PCU frame) on GUP board according to the channel,and form the TRU frame (PCU frame) into IP packet and sendit to TCU (or UPU) for processing.

IP Abis The hardware structure of IP Abis interface unit is shown in Figure25.



FIGURE 25 IP INTERFACE BIU HARDWARE STRUCTURE

IP interface BIU consists of the GIPI board and the GUP board.

1. As the interface board, GIPI accesses the IP packet from BTSthrough external Ethernet, and distinguishes the data of userplane and control plane.

� If it is of UDP type, then the data is sent to GUP for pro-cessing via user plane switching network.

� If it is of SCTP type, then the data is sent to CMP for pro-cessing via control plane switching network.

2. Uplink: On GUP, split the IP packet payload according to thechannel (the IP packet is formed according to carriers), searchthe 20 ms TRU frame (PCU frame) of each channel, and formthe TRU frame (PCU frame) of each channel into IP packet andsend it to TCU (UPU) for processing. Downlink: The processingsequence is the opposite.

IPoE Abis The hardware structure of IPoE Abis interface unit is shown inFigure 26.



FIGURE 26 IPOE INTERFACE BIU HARDWARE STRUCTURE

1. DTP implements E1 access.

2. EIPI implements conversion of PPP packet and IP packet, anddistinguishes the data of user plane and control plane.

� If it is of UDP type, then the data is sent to GUP for pro-cessing via user plane switching network.


3. Uplink: On GUP2, split the IP packet payload according to thechannel (the IP packet is formed according to carriers), searchthe 20 ms TRU frame (PCU frame) of each channel, and formthe TRU frame (PCU frame) of each channel into IP packet andsend it to TCU (UPU) for processing. Downlink: The processingsequence is the opposite.

5.1.4 AIU

In iBSC, A-interface has two types: E1 and IP.

E1 A The hardware structure of E1 A-interface unit is shown in Figure27.



FIGURE 27 E1 INTERFACE AIU HARDWARE STRUCTURE

E1 interface AIU consists of the DTB (or SDTB) board and the SPBboard.

1. The PCM voice channel is connected through E1 of the DTB (orSDTB) board and the SPB board, and then is switched to TCUthrough UIMU.

2. Basically, the SS7 signaling timeslot is connected through E1of SPB board, and directly performs MTP2 processing on SPB.It then forms the IP packet and sends it to CMP via controlplane switching network. The SS7 signaling timeslot can alsobe connected through DTB (or SDTB) of the current shelf, andthen switched to SPB for processing through UIMU.

IP A The hardware structure of IP A-interface unit is shown in Figure28.



FIGURE 28 IP INTERFACE AIU HARDWARE STRUCTURE

IP interface AIU consists of the GIPI board and the GUP2 board.

1. The GIPI board implements IP access and distinguishes thedata of user plane and control plane.

� If it is of UDP type, then the data is sent to GUP2 for pro-cessing via user plane switching network.


2. GUP2 performs the RTP procotol processing, and sends the pro-cessing result to BIU through GIUM.

5.1.5 PCU

PCU contains two logic units: GIU and UPU.

5.1.5.1 GIU

In iBSC, Gb interface has two types: E1 and IP.

E1 Gb The hardware structure of E1 Gb interface unit is shown in Figure29.



FIGURE 29 E1 INTERFACE GIU HARDWARE STRUCTURE

E1 interface GIU consists of the SPB board.

The SPB board implements E1 access, FR protocol processing, andseparating userplane and control plane of some data. It also sendsuser plane data to GUP for processing via user plane switchingnetwork, and sends control plane data to CMP for processing viacontrol plane switching network.

IP Gb The hardware structure of IP Gb interface unit is shown in Figure30.

FIGURE 30 IP INTERFACE GIU HARDWARE STRUCTURE



IP interface GIU consists of the GIPI board.

The GIPI board implements IP access and distinguishes the dataof user plane and control plane.

� If it is of UDP type, then the data is sent to GUP2 for processingvia user plane switching network.

� If it is of SCTP type, then the data is sent to CMP for processingvia control plane switching network, and some control planedata is sent to GUP for processing.

5.1.5.2 UPU

UPU consists of the UPPU board. It performs the following func-tions:

1. RLC/MAC protocol processing

2. Part of BSSGP protocol processing

3. Paging

4. Frame number synchronization

5.1.6 TCU

TCU consists of DRTB/DRTB2. It performs transcoding and rateadaptation.

5.1.7 PSU

The IP switching unit (PSU) provides a large-capacity non-conges-tion IP switching network for system control management, com-munication between service processing boards, and service streamconnection between multiple access units. PSU consists of two lev-els of switching subsystems.

1. The level-1 switching subsystem includes the PSN board andthe GLI board, which perform management and the functionsof core switching network card and line card.

2. The level-2 switching subsystem includes UIMC board,UIMU/GIUM board, and CHUB board. It is responsible forswitching and convergence of internal data stream on userplane and control plane.



5.2 User Plane Data Flow

5.2.1 User Plane Data Flow in CSDomain

Data Flow (LogicalUnit)

Figure 31 shows the user plane data flow in CS domain from theview of logical unit.

FIGURE 31 USER PLANE DATA FLOW IN CS DOMAIN (LOGICAL UNIT)

Here, the uplink direction is taken for example, the downlink di-rection is opposite.

BIU detaches the user plane data and the control plane data, sendsthe user plane data to TCU for processing. After the processing iscompleted, the data is sent to AIU. The flow direction is 1®2.

Data Flow (Shelf) Figure 32 shows the user plane data flow from the view of shelf.

FIGURE 32 USER PLANE DATA FLOW IN CS DOMAIN (SHELF)



Data Flow(Boards)

Figure 33 shows the user plane data flow from the view of boards.

FIGURE 33 USER PLANE DATA FLOW IN CS DOMAIN (BOARDS)

5.2.2 User Plane Data Flow in PSDomain

Data Flow (LogicalUnit)

Figure 34 shows the user plane data flow in PS domain from theview of logical unit.

FIGURE 34 USER PLANE DATA FLOW IN PS DOMAIN(LOGICAL UNIT)

Here, the uplink direction is taken for example, the downlink di-rection is opposite.

The PCU frame detached by BIU is sent to UPU (i.e. UPPB) via theuser plane switching network, and then the user plane data in PSdomain is detached by UPU for processing. After the processingis completed, the data is sent to GIU via the user plane switchingnetwork. The flow direction is 1®2.

Data Flow (Shelf) Figure 35 shows the user plane data flow from the view of shelf.



FIGURE 35 USER PLANE DATA FLOW IN PS DOMAIN (SHELF)

Data Flow(Borads)

Figure 36 shows the user plane data flow from the view of boards.

FIGURE 36 USER PLANE DATA FLOW IN PS DOMAIN (BOARDS)

5.3 Control Plane Signal Flow

5.3.1 Control Plane Signal Flow in CSDomain

Signal Flow(Logical Unit)

Figure 37 shows the control plane signal flow in CS domain fromthe view of logical unit.



FIGURE 37 CONTROL PLANE SIGNAL FLOW IN CS DOMAIN (LOGICAL UNIT)

1. Abis interface signaling flow

� BIU sends the signaling on LAPD channel as control planedata to CMP, and CMP processes the data and sends it toBIU. The flow direction is 1®1.

� Some signaling will generate A-interface signaling flow,which is sent to AIU. The flow direction is 1®2.

2. A-interface signaling flow

AIU performs MTP2 processing for A-interface signaling, andsends the data to CMP for MTP3 processing and upper layerprocessing. Some global processes involve OMP. The flow di-rection is 2®3®3®2 or 2®2.

Signal Flow(Shelf)

Figure 38 shows the control plane signal flow from the view ofshelf.

FIGURE 38 CONTROL PLANE SIGNAL FLOW IN CS DOMAIN (SHELF)



Signal Flow(Boards)

Figure 39 shows the control plane signal flow from the view ofboards.

FIGURE 39 CONTROL PLANE SIGNAL FLOW IN CS DOMAIN (BORADS)

5.3.2 Control Plane Signal Flow in PSDomain

Signal Flow (LogicUnit)

Figure 40 shows the control plane signal flow in PS domain fromthe view of logic unit.

FIGURE 40 CONTROL PLANE SIGNAL FLOW IN PS DOMAIN(LOGICAL UNIT)

1. Abis interface signaling flow

i. The control plane signaling from the Abis interface unit issent to CMP for processing. After being processed by CMP,some signaling, such as the immediate assignment mes-sage, is directly sent to BIU, and some signaling, such asthe packet assignment message, is sent to the user planeprocessing board. After being processed by the user planeprocessing board, the signaling is sent to BIU via user planeswitching network. The flow direction is 1®1 or 1®3®2.



ii. For data from the Abis interface unit, which should be pro-cessed by the user plane processing unit first, send it to theuser plane processing unit via user plane switching network(such as the uplink channel request on PACCH). After beingprocessed by UPU (such as the two-step access resourcerequest), the control plane signaling is detached and sentto CMP for processing. The flow direction is 2®3®3®2.

2. Gb interface signaling flow

i. GIU sends the data on signaling BVC channel as controlplane data to the home CMP for processing. After beingprocessed by CMP, some signaling, such as PTP BVC reset-ting, is forwarded to other CMPs for processing, and someglobal signaling, such as signaling BVC resetting, is for-warded to OMP for processing. After being processed byCMP or OMP, some signaling is generated as Abis signalingflow, such as PS-domain paging message and CS-domainpaging message, and the flow direction is 5®1 or 5®3®2;other signaling, such as PTP BVC resetting response andsignaling BVC resetting response, is sent to Gb interfacethrough GIU, and the flow direction is 5®5 or 6®6.

ii. GIU routes the data on other BVC channels to the userplane processing unit. The user plane processing unit de-taches the control plane data and sends it to CMP. Afterbeing processed by CMP, some signaling, such as PTP pag-ing message, is sent to Gb interface through GIU, and theflow direction is 4®3®5; some signaling is generated asAbis signaling flow, such as the location message, and theflow direction is 4®3®1.

Signal Flow(Shelf)

Figure 41 shows the control plane signal flow from the view ofshelf(1®1).

FIGURE 41 CONTROL PLANE SIGNAL FLOW IN PS DOMAIN (SHELF)(1®®®1)

Figure 42 shows the control plane signal flow from the view ofshelf(5®3®2).



FIGURE 42 CONTROL PLANE SIGNAL FLOW IN PS DOMAIN(SHELF)(5®®®3®®®2)

Signal Flow(Boards)

Figure 43 shows the control plane signal flow from the view ofboards(1®1).

FIGURE 43 CONTROL PLANE SIGNAL FLOW IN PS DOMAIN (BOARDS)(1®®®1)

Figure 44 shows the control plane signal flow from the view ofboards(5®3®2).



FIGURE 44 CONTROL PLANE SIGNAL FLOW IN PS DOMAIN(BOAEDS)(5®®®3®®®2)


Chapter6 Interface and Protocol


>> Interfaces>> Protocols

6.1 Interfaces

6.1.1 A-Interface

The interface between BSC and MSC is called A-interface. Moreaccurately, A-interface is the interface between TC and MSC.

Transcoder implements the voice transformation between voicecoding and 64 kbps A law PCM coding. At the same time, it per-forms the data rate adaptation in the circuit data service. TC canbe either at BSC side or MSC side

The A-interface of iBSC supports three kinds of interfaces.

1. E1 interface

In this case, iBSC is connected with MSC by 75 Ω coaxial cableor 120 Ω twisted pair.

At A-interface, the data link layer employs MTP2 protocol, thenetwork layer employs MTP3 protocol and SCCP protocol, andthe application layer employs BSSMAP protocol.

2. STM-1 interface

In this case, iBSC is connected with MSC by optical fiber.

3. IP interface

In this case, iBSC is connected with MSC by network cable.

6.1.2 Ater Interface (TC Is External)

The interface between iBSC and iTC is called Ater interface.TransCoder (TC) is separated from iBSC and exists as an indepen-dent system iTC, which facilitates dynamic TC resource sharing.For more details, refer to ZXG10 iTC Transcoder Pool SystemDescription.

The Ater interface of iBSC supports two kinds of interfaces.

1. E1 interface

In this case, iBSC is connected with iTC by 75 Ω coaxial cableor 120 Ω twisted pair.



At Ater interface, the data link layer employs MTP2 protocol,the network layer employs MTP3 protocol and SCCP protocol,and the application layer employs Ater interface applicationlayer protocol.

2. STM-1 interface

In this case, iBSC is connected with iTC by optical fiber.

6.1.3 Abis Interface

The interface between BSC and BTS is called Abis interface. BSCis connected with BTS via Abis interface. Abis interface is the in-ternal user-defined interface of ZXG10 BSS. When E1 is used fortransmission, Abis interface supports various networking modes,such as star networking, chain networking, tree networking, andring networking.

The Abis interface of iBSC supports four kinds of interfaces.

1. E1/T1 interface

If Abis interface adopts E1 interface, iBSC is connected withBTS by 75 Ω coaxial cable or 120 Ω twisted pair.

If Abis interface adopts T1 interface, iBSC is connected withBTS by 100 Ω twisted pair.

At Abis interface, the data link layer employs LAPD protocol,and the upper layer employs application protocols such as RR.

2. IP interface

In this case, iBSC is connected with BTS by network cable oroptical fiber.

3. STM-1 interface

In this case, iBSC is connected with BTS by optical fiber.

4. IPoE interface

In this case, iBSC is connected with BTS by 75 Ω coaxial cableor 120 Ω twisted pair.

6.1.4 Gb Interface

The interface between BSC and SGSN is called Gb interface. BSCis connected with SGSN via Gb interface.

Gb interface supports two kinds of interfaces.

1. E1 interface

iBSC is connected with SGSN by E1 cable. The data access ratecan be N×64 kbps (1≤N32) or 2048 kbps. The timeslot andbandwidth used on E1 cable are specified by the operator.

At Gb interface, iBSC implements FR protocol, NS protocol andBSSGP protocol.

2. IP interface


Chapter 6 Interface and Protocol

In this case, iBSC and SGSN are connected by network ca-ble, and iBSC implements IP-related protocols, NS protocol andBSSGP protocol.

6.1.5 OMC Interface

OMC interface is the interface connecting iBSC background NMSand iBSC foreground equipment. The network management soft-ware can perform management and configuration for iBSC boardsthrough this interface. The equipment communicates with NMSthrough TCP/IP protocol.

6.1.6 CDR Interface

CDR interface is the interface between iBSC and MR server. iBSCand MR server are connected by network cable.

6.2 Protocols

6.2.1 CS Domain Protocols

The CS domain protocol stack is used to process protocols relatedto voice data of each layer.

6.2.1.1 Control Plane Protocols in CS Domain

Figure 45 shows the control plane protocol stack in CS domainunder E1/T1 or STM-1 transmission mode. Here, assume that TCis internal.

FIGURE 45 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN

1. Um interface



The control plane protocol stack in CS domain at Um interfaceis shown in Figure 46

FIGURE 46 CIRCUIT SERVICE PROTOCOL STACK AT UM INTERFACE

i. Transmission layer (physical layer)

As the first layer at Um interface, it provides the transmis-sion channel of radio link and transmits data by radio wave.It also provides channels with different functions for upperlayers, including service channel and logic channel.

ii. Data link layer

As the second layer at Um interface, it provides reliabledata link between MS and BTS. It employs the LAPDm pro-tocol, which is the dedicated protocol for GSM system. TheLAPDm protocol is the variation of the LAPD protocol.

iii. Application layer

As the third layer at Um interface, it controls and managesprotocols, arranging system information on specified logicchannels according to certain protocols. It contains threesub-layers: CM, MM, and RR.

– CM layer

It implements communication management, estab-lishes connection between subscribers, and holds/re-leases calls. Such functions can be divided into CallControl (CC), Subjoin Service Management (SSM), andShort Message Service (SMS).

– MM layer

It performs mobility and security management and im-plements processing when MS initiates location update.

– RR layer

It performs radio resource management, and estab-lishes/releases the connection between MS and MSCduring the call.

2. Abis interface

In iBSC, Abis interface can transmit data in three ways: E1, IP,and IPoE.



� Under E1 or STM-1 transmission mode, the control planeprotocol stack in CS domain at Abis interface is shown inFigure 47.

FIGURE 47 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN ATABIS INTERFACE (UNDER E1 OR STM-1 TRANSMISSION MODE)

a) Layer1 – physical layer

This layer could employ 2 Mbps E1 cable or category-5network cable.

b) Layer2 – data link layer

This layer employs the LAPD protocol, which is apoint–to–multipoint communication protocol and asubset of Q.921 standard, LAPD adopts the framestructure, including flag field, control field, informationfield, parity field, and flag sequence. The flag fieldincludes Service Access Point Identifier (SAPI) andTerminal Equipment Identifier (TEI), which indicate theaccessed service and entity.

c) Layer3 – application layer

This layer performs radio link management and opera-tion & maintenance function.

� Under IP transmission mode, the control plane protocolstack in CS domain at Abis interface is shown in Figure 48.

FIGURE 48 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN ATABIS INTERFACE (UNDER IP TRANSMISSION MODE)

� Under IPoE transmission mode, the control plane protocolstack in CS domain at Abis interface is shown inFigure 49.



FIGURE 49 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN ATABIS INTERFACE (UNDER IPOE TRANSMISSION MODE)

3. A-Interface (TC is internal)

� Under E1 or STM-1 transmission mode, the control planeprotocol stack in CS domain at A-interface is shown inFigure 50.

FIGURE 50 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN ATA-INTERFACE

a) Layer1 – physical layer

It defines the physical layer structure of MSC and BSC,including physical and electrical parameters and chan-nel structure.

It employs the first level of Message Transfer Part (MTP)in No. 7 signaling on common channels, and uses 2Mbps PCM digital link as transmission link.

b) Layer2 – data link layer and network layer

MTP2 is a variation of High-level Data Link Control(HDLC) protocol. The frame structure includes flagfield, control field, information field, parity field, andflag sequence.

MTP3 and SCCP implements functions such as signalingroute selection.

c) Layer3 – application layer



This layer includes Base Station System Application Part(BSSAP). It performs maintenance and managementfor BSS resource and connections, and controls serviceconnection and release.

� Under IP transmission mode, control plane protocol stackin CS domain at A-interface is shown in Figure 51.

FIGURE 51 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN ATA-INTERFACE (UNDER IP TRANSMISSION MODE)

4. Ater interface (TC is external)

The control plane protocol stack in CS domain at Ater interfaceis shown in Figure 52.

FIGURE 52 CONTROL PLANE PROTOCOL STACK IN CS DOMAIN AT ATERINTERFACE

i. Layer1 – physical layer

It defines the physical layer structure of iTC and iBSC,including physical and electrical parameters and channelstructure.

It employs the first level of Message Transfer Part (MTP)in No. 7 signaling on common channels, and uses 2 MbpsPCM digital link as transmission link

ii. Layer2 – data link layer and network layer

MTP2 is a variation of High-level Data Link Control (HDLC)protocol. The frame structure includes flag field, controlfield, information field, parity field, and flag sequence.



MTP3 and SCCP implements functions such as signalingroute selection.

iii. Layer3 – application layer

It includes Ater interface application layer protocol, andperforms Ater interface circuit management and TC re-source request and release.

6.2.1.2 User Plane Protocols in CS Domain

1. Figure 53 shows the user plane protocol stack in CS domainunder E1 or STM-1 transmission mode.

FIGURE 53 USER PLANE PROTOCOL STACK IN CS DOMAIN (UNDER E1TRANSMISSION MODE)

AMR/FR/EFR/HR coding can be used for voice service transmis-sion and RLP protocol can be used for data service transmis-sion.

2. IP transmission mode and IPoE transmission mode

i. Under IP transmission mode, the user plane protocol stackin CS domain at Abis interface is shown in Figure 54.

FIGURE 54 USER PLANE PROTOCOL STACK IN CS DOMAIN AT ABISINTERFACE (UNDER IP TRANSMISSION MODE)

ii. Under IP transmission mode, the user plane protocol stackin CS domain at A-interface is shown in Figure 55.



FIGURE 55 USER PLANE PROTOCOL STACK IN CS DOMAIN ATA-INTERFACE (UNDER IP TRANSMISSION MODE)

iii. Under IPoE transmission mode, the user plane protocolstack in CS domain at Abis interface is shown in Figure 56.

FIGURE 56 USER PLANE PROTOCOL STACK IN CS DOMAIN AT ABISINTERFACE (UNDER IPOE TRANSMISSION MODE)

6.2.2 PS Domain Protocols

PS domain protocol stack is used to process protocols related topacket data of each layer.

6.2.2.1 Control Plane Protocols in PS Domain

Figure 57 shows the control plane protocol stack in PS domain.



FIGURE 57 CONTROL PLANE PROTOCOL STACK IN PS DOMAIN

GMM/SM performs GPRS mobility management and session man-agement protocol processing, including attach/detach, securitymanagement, routing area update, location area update, and PDPcontext activation/deactivation.

For details of other layers, refer to User Plane Protocols in PS Do-main.

6.2.2.2 User Plane Protocols in PS Domain

Figure 58 shows the user plane protocol stack in PS domain.

FIGURE 58 USER PLANE PROTOCOL STACK IN PS DOMAIN

1. Um interface

i. GSM RF

The physical layer of Um interface is the RF interface part,which employs the same transmission mode as GSM circuitservice. It specifies carrier characteristics, channel struc-ture, modulation mode, and RF indices.

ii. RLC/MAC layer



RLC is the radio link control protocol at the air interfacebetween BTS and MS. It performs error detection for datablocks and decides the error data block to be retransmitted.

MAC controls the access signaling flow on radio channel. Itmakes decision when a lot of MSs access the shared media,and maps the LLC frame to the GSM physical channel.

Compared with the MAC function under A/Gb mode, theMAC of GERAN has the following features:

– Supports one MAC entity with many TBFs.

– Supports MAC layer encryption

iii. LLC layer

LLC is a radio link protocol based on High speed Data LinkControl (HDLC). It can provide reliable encrypted logicallink. LLC layer generates LLC address and frame filedfrom the SNDC data unit of upper SNDC layer, to gener-ate the complete LLC frame. In addition, LLC performspoint–to–multipoint addressing and retransmission controlof data frame. LLC is independent from the bottom-layerradio interface protocol, in this way, the change of NetworkSubSystem (NSS) is the minimum when other GPRS radiosolutions are used. GSM04.64 standardizes LLC.

iv. SNDCP

As the transition between network layer and data link layer,SNDCP packets the transmitted data, sends them to LLClayer for transmission, and decides TCP/IP address and en-cryption mode.

In SNDC layer, the transmitted data between MS and SGSNis divided into one or multiple SNDC data packets. TheSNDC data packet is put into LLC frame after being gener-ated.

v. Relay

Relay forwards the LLC PDU between Um interface and Gbinterface.

2. Gb interface

i. Layer1 – physical transmission layer

This layer could employ 2 Mbps E1 cable or category-5 net-work cable.

ii. Network Service (NS)

This layer is based on frame relay, and is used to transmitthe upper-layer BSSGP PDU.

iii. BSSGP

At the transmission platform, this protocol provides a con-nectionless link between BSS and SGSN to transmit datawithout confirmation.

iv. IP

The Internet protocol defined in RFC 791 is used for userdata routing and signaling control. When FE is used fortransmission between iBSC and SGSN, the data link layerat Gb interface uses IP protocol.



v. FR

Frame relay provides the permanent virtual circuit, whichtransmits user data and signaling at Gb interface. When E1is used for transmission between iBSC and SGSN, the datalink layer at Gb interface uses FR protocol.


Chapter7 Networking


>> Abis Interface Networking Modes>> A-Interface Networking Mode>> Ater Interface Networking Mode>> Gb Interface Networking>> OMC Interface Networking Modes

7.1 Abis Interface NetworkingModesiBSC supports all series of ZXG10 BTS products and can configurecorresponding BTS networking modes according to actual require-ments.

1. Using E1 for transmission

When E1 is used for transmission at Abis interface, the systemsupports star networking, chain networking, tree networking,and ring networking.

The star networking mode at Abis interface is shown in Figure59.

FIGURE 59 ABIS INTERFACE STAR NETWORKING

In a star network, each site is directly connected to BSC. Thestar networking mode is simple, links are reliable, and mainte-nance and construction is convenient. This mode is applicablein a densely populated area.

The chain networking mode at Abis interface is shown in Figure60.



FIGURE 60 ABIS INTERFACE CHAIN NETWORKING

A chain network uses less transmission equipment becauseZXG10 BTS has the bypass direct through–connection func-tion. In other words, BTS disconnection can be recovered byconnecting other BTS in the chain, which guarantees normalequipment running. This mode is applicable in strip-shapedarea.

The tree networking mode at Abis interface is shown in Figure61.

FIGURE 61 ABIS INTERFACE TREE NETWORKING

The tree networking mode is a little complex, signal passesthrough many nodes, thus the link reliability is comparativelylower. Moreover, any fault in upper level site might affect thelower level site. Therefore, this mode is not often used. Thismode is applicable in large area with sparse population.

The ring networking mode at Abis interface is shown in Figure62.

FIGURE 62 ABIS INTERFACE RING NETWORKING

Ring networking is the most useful and advanced network-ing mode in GSM communication structure. If the site link isbroken, the communication starts from the opposite direction.This enhances the security of BSS network services.


Chapter 7 Networking

In practice, these modes are often used in combination toachieve the best cost-effectiveness.

2. Using IP for transmission

When IP is used for transmission, the BTS that accesses iBSCfalls into two types: macrocell BTS and microcell BTS.

The typical application scenario of iBSC IP Abis is shown inFigure 63.

FIGURE 63 TYPICAL IP ABIS ACCESS OF IBSC

Generally, the macrocell BTS accesses iBSC directly throughdedicated cable.

The microcell BTS can access iBSC in many ways, including:

� Accessing iBSC through the Internet by ADSL at home.

� Arranging BTS inside the enterprise network and making itaccess iBSC through the Internet via enterprise gateway.

� Accessing iBSC through IP dedicated cable of the macrocellBTS.

7.2 A-Interface Networking Mode1. Adopting E1 transmission at A-interface



� When the core network is 2G MSC, the networking modeat A-interface is shown in Figure 64.

FIGURE 64 E1 A-INTERFACE NETWORKING MODE (2G MSC)

� When the core network is 3G CN, the networking mode atA-interface is shown in Figure 65.

FIGURE 65 E1 A-INTERFACE NETWORKING MODE (3G CN)

In this case, the user plane data is processed by MGW, thecontrol plane data is processed by MSC Server.

2. When IP transmission is adopted at A-interface, the networkingmode at A-interface is shown in Figure 66.

FIGURE 66 IP A-INTERFACE NETWORKING MODE

In this case, the user plane data is processed by MGW, thecontrol plane data is processed by MSC Server.

7.3 Ater Interface Networking ModeFigure 67 shows the Ater interface networking mode of iBSC whenE1 is used for transmission.

FIGURE 67 ATER INTERFACE NETWORKING



7.4 Gb Interface NetworkingWhen ZXG10 iBSC and SGSN is connected by E1 cable, the Gbinterface function is implemented through E1-based frame relayprotocol.

The Gb interface networking includes straight-through connectionmode and iBSC cascading mode. shows the Gb interface straight-through connection mode and iBSC cascading mode.

FIGURE 68 GB INTERFACE NETWORKING

Bandwidth permitting, multiple iBSCs can be cascaded and thenconnected to SGSN to save Gb interface line resources. The iBSCcascading mode is very convenient. For example, iBSC1 is directlyconnected to SGSN, iBSC2 can be directly connected to other PCMports of DTB of iBSC1 through E1 cable. Through configuration,a transparent transmission from iBSC2 to SGSN without E1 trans-mission can be implemented, saving system resource greatly.

7.5 OMC Interface NetworkingModesThe iBSC system contains OMM and NetNumen M31. OMM is apart of iBSC and is used for operation and maintenance of iBSC.iBSC is connected with NetNumen M31 through OMM.

In iBSC, OMM hardware platform uses the SBCX board. SBCXadopts active/standby configuration, which enhances the reliabil-ity of OMM.

iBSC supports local maintenance networking and remote main-tenance networking. The local maintenance networking meansthat iBSC interconnects NetNumen M31 through LAN. The remotemaintenance networking means that iBSC interconnects NetNu-men M31 through DCN , including PCM and IP backbone network.

� Local maintenance networking

It is the simplest and most commonly used mode. In thismode, iBSC and NetNumen M31 are located in the same LAN



and connected via Ethernet. NetNumen M31 and the iBSCsthat it manages are physically at the same location, and theyare connected by LAN.

Figure 69 shows the local maintenance networking when iBSCOMM adopts the SBCX configuration. In this case, the OMP1port (it is recommended to set the IP address within networksegment 129) on the rear board of SBCX is connected withOMP and LMT through LAN Switch. User performs operationand maintenance through the LMT terminal. The OMC1 port (itis recommended to set the IP address within network segment10) on the rear board of SBCX is connected with the NetNu-men M31 server through LAN Switch, to access the networkmanagement system.

FIGURE 69 IBSC LOCAL OPERATION & MAINTENANCE (SBCXCONFIGURATION)

� Remote centralized maintenance networking

In the PCM networking mode for remote centralized mainte-nance, the 2 Mbps PCM link (A-interface E1) is available be-tween MSC and iBSC, or other dedicated PCM links are avail-able, and they can be used to transmit network managementinformation. In this mode, the timeslot in PCM link is usedto transmit operation and maintenance information at a rateof n × 64 kbps, here, n is the number of occupied timeslots.PCM equipment is used to extract a certain number of times-lots from the PCM links for operation and maintenance. Thisapproach is economical, practical, and fully utilizes available



resources. Figure 70 shows the PCM networking mode for re-mote centralized maintenance.

FIGURE 70 IBSC REMOTE PCM NETWORKING MODE

Figure 71 shows the IP backbone-network transmission net-working mode for the remote centralized maintenance.

FIGURE 71 IBSC REMOTE IP NETWORKING MODE


Chapter8 Operation andMaintenance


>> Maintenance Overview>> Maintenance Functions

8.1 Maintenance OverviewThe maintenance of SDR involves remote maintenance and localmaintenance. Figure 72 shows the maintenance system network-ing of SDR.

FIGURE 72 GERAN MAINTENANCE NETWORKING

� Remote maintenance(Remote Client)

In remote maintenance, NetNumen M31, the general radioNetwork Element (NE) management system, is connected withOMM of BSC/RNC, and then connected with the base stationthrough Abis interface or Iub interface to implement operationand maintenance.

� Local maintenance(LMT)

In local maintenance, PC is directly connected with the basestation through Ethernet cable to implement operation andmaintenance.



8.2 Maintenance FunctionsIn NetNumen M31, the O&M interface of remote maintenance sys-tem is in the form of topological graphics. Information of each NEin the network can be viewed on the interface. Users can selectthe NE to be maintained and check its performance data, alarminformation, and configuration data. Users can also perform main-tenance for a certain type of NEs through the topological graphicsinterface.

The maintenance system performs the functions is shown in Figure73.

FIGURE 73 EMS FUNCTIONS

� Configuration management

In configuration management, physical/radio resource datacan be added, queried, deleted, and modified for the basestation. It also performs data consistency check, and supportsdynamic data configuration and static data configuration.

� Security management

It guarantees that only authorized users can perform relevantcommand group operations.


It implements performance analysis, call tracing, and signalingtracing.

� Version management

With version management, users can view hardware/softwareversions running at the foreground. The background providesa software downloading system for software upgrade at theforeground.



Chapter 8 Operation and Maintenance

Fault management includes alarm management and diagnosisand test. It performs centralized monitoring of running sta-tus of the base station and collects abnormal information ofboards and links in real time. These functions make it con-venient for operation and maintenance personnel to performanalysis, make decision, and implement maintenance and re-pair.


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