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Product Concepts Engineering Operations Service Flows Special Terms

Contents

IMS System

What is IMS?

☺IMS (IP Multimedia Subsystem) is a sub-system introduced in the Release 5 of 3GPP that supports IP multimedia services.

☺It adopts SIP and access unrelativity.

☺It realizes mobility management, multimedia session signaling and carrier service transmission and end-to-end IP services.

☺IMS system adopts layered structure so access, bearer, control and service are completely separated, which facilitates technological evolution of each layer. Carrier can focus on access, control and service capacity while cooperate with SP in services.

What is IMS?

CSCF, Call Session Control Function, is the core of IMS system. It realizes call and session control in IMS.

HSS, Home Subscriber Server, is the DB that holds subscription information and location information of subscribers. It develops from HLR.

MGCF, Media Gateway Control Function, and IMS-MGW, IMS-Media Gateway, are for interworking with CS domain and PSTN. They are charged with control of interworking between signaling and media flows.

MRFC, Multimedia Resource Function Controller, and MRFP, Multimedia Resource Function Processor, are for conference calls. MRFC of the control layer controls MRFP through H.248.

BGCF, Breakout Gateway Control Function, is the joint of IMS system and external network. It decides where IMS system should be connected with CS domain or PSTN.

End MSC/TMSC/GMSC

★ End MSC End MSC directly serves subscribers. It is the basic unit f

or signaling processing and sending/receiving of messages. It is at the bottom layer. End MSC analyzes subscriber information and choose if the call should be sent to destination end office via TMSC or GMSC.

★ TMSC End offices are connected by TMSC if there is no direct c

onnection. TMSC consists of traffic-tandem switches. ★ GMSC GMSC is responsible for interworking and interconnectio

n with other networks or carriers. It can get location information of called MS from HLR and choose route according to the information.

What is V1/V2/V3?

Mobile Customer Service Department of Nanjing is responsible for maintenance and technical support to V1, V2 and V3 mobile switch systems.

★ V1 is the traditional TDM-based GSM switches. ★ V2 supports 3G services that are based on R99 of

3GPP. It is mainly used in early trials of WCDMA. ★ V3 uses a brand-new all-IP hardware platform,

supporting GSM, PCS and 3GPP R4 and above. It can be the substitution of V1 or used as core network of WCDMA and TD-SCDMA systems.

Dynamic/static Data and Synchronization

Static data: Data changed through background provisioning, such as authentication and subscription information of subscribers

Static data sync

BOSS transfer

Interface processor transfer

DRSync (recommended)

Dynamic data sync

Dynamic data: Data controlled by subscribers or changed by service operations, such as location information, supplementary service registration data and dynamic service identifiers.

MSC1 MSCn

I nter-HLR si gnal i ng l i nkDynami c data sync

Acti ve si gnal i ngAc

t ive

si g

nal i

ngStandby si gnal i ng

St andby si gnal ing

HLR1 HLR2

What is OCS

OCS is the short for Online Charging System. Most of today’s carriers use semi-realtime charging and SCP CAMEL3 prepay for their PS systems.

OCS does not have the shortcomings that traditional billing methods suffer. GGSN achieves real-time charging through interconnection between Diameter interface and OCS system. GGSN applies for quota from OCS when subscriber originates service and OCS checks subscriber state and distributes a certain amount of quota (volume or duration). After the quota is used out, GGSN sends application to OCS again and OCS deducts from subscriber’s account and distributes some quota. By such means, subscribers can be charged in a real-time fashion and deliberate defaulting of payment can be prevented. The combination of GGSN’s content-based charging and OCS can help us to realize service type-based charging, which is impossible for SCP CAMEL3. Service type-based charging facilitates service marketing and differentiated operation so that carriers can quickly push forward various tariff and service packages, thus strengthening competitive edge of feature services. Meanwhile, content-based charging of common services makes bills very clear to subscribers and transparent charging makes subscribers more at ease, thus improving loyalty of subscribers.

What is dual-net-dual-plane? (I)

Background network:

our OMM server and USI boards need to connect with background network through dual-net-dual-plane. To do that, we need a pair of L2 cascade switches and all equipment that needs to connect with switch are connected with the two switches through two cables. The equipment provides one external IP address. For OMM server, the two network cards are bundled into a TEAM while, for USI board, they are physically configured as 1+1 mode. The equipment communicate with outside through one network card of the active node when everything is all right. But once the active switch or active network card of connected equipment is out of order, the IP address will float to the other network card of the active node and data exchange between the active node and other active nodes needs to be transferred between the two switches, which takes place in the cascade cable between the two switches.

What is dual-net-dual-plane? (II)

Foreground network

As for foreground network, dual-net-dual-plane is used when active and standby SIPI boards are connected to IP bearer network. When CE works in active-standby mode, CN nodes, MSCS and MGW, shall both be connected to CE routers in active-standby mode and we need to choose 1+1 active-standby mode when configuring SIPI boards at OMC. Active and standby SIPI boards share an IP address.

When active SIPI is out of order, standby SIPI will switch to active and starts to transfer packets with the same IP address. Under such situation, data transfer between the SIPI board and other interface boards will also be transferred between the two cascade switches. As for plane A and B of LSTP, LSTP points are configured in pairs. All signaling points in LSTP service area will be connected to LSTPs of different planes to provide load-sharing and service restoration in case fault happens. Two planes of LSTP use heartbeat to ensure that LSTP of both planes can be clear of SP status in signaling network.

Product Concepts Engineering Operations

Service Flows Special Terms

What is one-restart-one-sync?

One-restart-one-sync means restarting OMP and other boards and then synchronize data. Data sync sends configuration data held in OMC server to the foreground so network elements at the foreground can get configurations from OMC server.

After boards are restarted, OMP board downloads version files from OMC server and other boards download their version files from OMP board after they are restarted. 。

Why we need three-sync-three-restart?

ZTE’s mobile CN products experienced three stages, V1(mainly ZXJ10), V2 (mainly GPRS) and V3 (3G platform). In V1, V2 and earlier days of V3, the first sync sends foreground table structure and allocates DB capacity. The second sync sends configuration data. Usually the configurations take effect after the second sync and MP restart. To make sure all data are correct, we performs the third sync of all tables. After changing foreground version and cleaning foreground data, we carry out the first restart of MP and synchronize tables after the restart. So MP needs three restarts and three syncs every time MP is re-configured or upgraded. Note: Now foreground table sync method of V3 system has been changed and table structure and configurations can be all synchronized to the foreground by one action. However, to guarantee data integrity and correctness, we usually conduct two syncs and two restarts.

What’s the significance of IP-lization?

Significance of IP-lization The split of control and user planes al

lows the mobile soft-switch technology to go down the road of all-IP network meanwhile without having to give up the traditional TDM bearer.

The TrFO technology based on multi-bearer requires less CODEC and strikes a balance between voice quality and CN bandwidth conservation.

Capacity of MSS, located in control plane, is greatly improved as compared to old exchanges and can be deployed in the center while MGWs can be deployed in satellite networks, making network architecture simple and clear.

Plane voice bearer over IP

What’s the significance of IP-lization?

Characteristics of WCN equipment after IP-lization Split of call and bearer in CS domain: MSC is div

ided into MSC Server and MGW, thus call control and bearer are completely separated. 。

Stage 3 of No.7 signaling transmission in CN: Support transmission of No.7 signaling in various network modes, including networks based on MTP, IP and ATM, between two functional entities of CN.

CS domain can adopt transmission modes of TDM, ATM and IP.

NNI adopts BICC signaling newly-defined by ITU so control and bearer are irrelevant to each other.

Traffic net adopts IP-borne flat architecture. Calling TMGW can talk to called TMGW under the control of TMSC.

CMN is introduced to signaling network for signaling tandem. CMN does not have bearer control function.

Difference of 2G/3G Authentication

Authentication algorithm 2G： China Mobile and China Unicom both use co

mp128-1 for authentication of their 2G networks. 3G： 3G authentication parameters are more com

plicated, including C1, C2, C3, C4, C5, R1, R2, R3, R4, R5 and OP or OPC. China Mobile uses OPC and China Unicom uses OP.

Ki Encryption China Mobile’s Ki is not encrypted China Unicom’s Ki is and the decryption key can on

ly be configured by someone from the head-office and provincial branches do not have it in hand.

Please confirm on parameters with the carrier in advance to avoid unnecessary defer.

Handover

Intra-office HO: Subscriber originates HO due to such reasons as poor signal under BSC/RNC of present MSC Server and the BSC/RNC he/she hands over to is also under the present MSC Server.

Inter-office HO: The BSC/RNC subscriber hands over to belongs to another MSC.

Out-HO: Subscriber switches to BSC/RNC of another MSC

In-HO: Subscriber switches into BSC/RNC of present MSC from another MSC

Out-and-back HO: Subscriber switches back to BSC/RNC of present MSC after switch out

In-and-back HO: Subscriber switches back to BSC/RNC of the original MSC after switch into the present MSC

HO to third party: Subscriber switches to BSC/RNC of a third MSC after switch into the present MSC

Reasons of Low HO Success Rate

Quick troubleshooting for low HO success rate Check performance stat. to see if the drop happens at specific pe

riod, for example evening peak. Number of HO re-tries at busy hours increases sharply and, as a result, there will be more HO failures.

Check if any areas under control of other offices are covered by wireless network of the present office as such problem can lead to rise of HO frequency and drop of HO success ratio.

Analyze statistical data prior to occurrence of the problem and see if any configuration has been changed at opposite-side office, wireless side and CN itself.

Check basic traffic stat. and link load to see if there is any fluctuation.

Record call loss information in all modules. Check if there are any abnormal call losses. Pay attention to call losses that appear in batches with even distribution. Described below is analysis for main call losses that affect HO success ratio.

How does 2G-to-3G HO happen?

MML Command->Access Configuration->Location Area->Create LA: Configure target 3G LA in 2G MSC. Fill 3G MSC /VLR number in MSC ID/VLR ID and choose “NO_MSC” in home MSC.

Specialized Maintenance->Variable Control->System Control Parameters: Modify 2G MSC security variable “sending MAP phase” as R99.

MML Command->Protocol Configuration->N7 Signaling->SCCP Data->GT Translation->Create GT Translation: Configure GT analysis of 3G MSCS number in GT translation of 2G MSCS. Be sure to choose MAP phase of R99 and higher.

MML Command->Number Analysis->Calling Number Analysis->Called Number Analysis->Create Called Number Analysis: Configure HO number of 3G MSCS in Called Number Analysis

MML Command->Advanced Configuration->HO Policy->Change HO Parameter: Modify the 2G MSCS HO parameter of “Allow subscriber to HO from GSM to UMTS” at the target side. Default value of the parameter is “NO”, i.e. 2G-to-3G HO is not allowed. In the 630 version, “GSM-to-UMTS HO” should be allowed.

MML Command->Advanced Configuration->HO Policy->Change HO Parameter: Modify the 3G MSCS HO parameter of “Allow subscriber to HO from GSM to UMTS” at the target side. Default value of the parameter is “NO”, i.e. 2G-to-3G HO is not allowed. In the 630 version, “GSM-to-UMTS HO” should be allowed.

How does 3G-to-2G HO happen?

MML command->Access configuration->Location area->Create LA: Configure target 2G LA at 3G MSC. Fill 2G MSC /VLR number in MSC ID/VLR ID and choose “NO_MSC” in home MSC.

MML Command->Protocol Configuration->N7 Signaling->SCCP data->GT Translation->Create GT Translation: Configure GT analysis of 2G MSCS number in GT translation of 3G MSCS.

MML Command->Number Analysis->Calling number Analysis->Called Number Analysis->Create Called Number Analysis: Configure HO number of 2G MSCS in called number analysis of 3G MSCS.

MML Command->Advanced Configuration->HO Policy->Change HO Parameter: Check source 3G MSCS HO parameter of “allow subscriber to HO from UMTS to GSM”. Default value of the parameters is YES, i.e. allow 3G-to-2G HO.

MML Command->Advanced Configuration->HO Policy->Change HO Parameter: Check target 2G MSCS HO parameter of “allow subscriber to HO from UMTS to GSM”. Default value of the parameters is NO, i.e. prohibit 3G-to-2G HO.

Why CIC and SLC need to be negotiated? CIC

CIC means circuit ID code. Every voice channel in circuit group has one CIC. Though CIC is assigned to voice channel, the voice channel itself does not have the capability of showing its identity to the opposite side and CIC of voice channel is just an internal code. After signaling is received or subscriber makes operation, MSC carries out necessary operation to voice channel marked with the CIC. Meanwhile MSC at the opposite side conducts operation according to signaling message and subscriber’s operation. What will happen if MSCs at two sides have different definitions for CIC? Actually signaling links will not be affected and signaling flows will all appear normal. However, MSC’s operation on voice channel will go wrong. When MSC at out side starts dialog to voice channel, MSC at the other side should perform the same operation so that subscribers at two sides can talk to each other.

SLC SLC means signaling link code. It is used to mark links in one link set. Which SLC a message will pass through is determined by result of AND of SLS and the mask input during creating of SP or signaling link set. If SLC codes defined at two sides are not consistent, AND will have different results according to the rule and different links will be selected at two sides so MSCs at two sides cannot be connected.

Why one SPB can only support 4 E1s and 64 64K signaling links?

One time-divided multiplex frame of E1 is divided into 32 equal time slots, numbered from CH0 to CH31. Each time slot occupies 8 bits in E1 frame, 8*8k=64k, so one E1 contains 32×64K. That means 8×32=256bit for 32 time slots and 8k E1 frames pass through interface every second, which means 8K×256=2048Mbps. Therefore, data rate of PCM E1 is 2.048Mbit/s and one E1 is one 2.048M link.

SPB board has 16 E1s, 4 8M Highway interfaces and a number of CPUs. It is used for NB signaling processing, mainly HDLC of No.7 signaling messages and signaling below the MTP2 layer.

SPB board supports both 64K and 2M signaling links. It supports up to 4 2M or 64 64K signaling links, depending on sub-card it uses. We can configure up to 4 82XX sub-cards in SPB board. The first sub-card is used for controlling, responsible for internal time slot switching, E1 data processing and lamp state. Besides that, the sub-card needs to handle MTP2 signaling messages of links configured at it together with other sub-cards. The sub-cards are independent and do not have any message exchange with each other. Due to capacity limit of 82XX sub-card, we only open MCC No. 2 at present through each sub-card can handle two MCCs. So each sub-card can support only one 2M link and the four sub-cards can support 4 2M links in total.

Each MCC has 32 time slots and 4 sub-cards have 128 time slots. Theoretically, every time slot can establish a 64K link. However, for safety concern, we only use half of them, which means 128*50%=64 links.

Why should the O & M node be configured as the 129 node?

The concept of 129 node/module is passed down from ZXJ10. ZXG10 inherited it from ZXJ10 and most of its concepts. ZXWN-WCN inherited it from ZXG10 and some of its concepts remain unchanged. In ZXJ10 system, there are maximally 64 modules at the foreground and each module has an address. The last segment of address of Module 1 (active) is 1 and the last segment of address of Module 1 (standby) is 65. Therefore, there needs to be 128 IP addresses for all the active and standby modules so the last segment of IP address of OMC server has to start from 129. That is why background O&M module is defined as the 129 module. The concept of 129 module was inherited in the ZXG10-MSS system and, thus, the new concept of 129 server came into being. We consider it as the OMC server by default and we can tell it by seeing if the last segment of its IP address is 129.

Why do we use toothpick or clip to reset a board?

In V3 version upgrades, we need to reset boards so that they can download new versions. To reset the boards, we usually use toothpick or clip to press the reset button. The hole of the reset button is tiny so we can only use such tool. However, the method has a few shortcomings.

We may miss board and missed boards will be unable to download new versions.

Even if we use toothpick or clip, board may fail to be reset sometimes and we need to confirm the reset through other means.

Customers think this method is too primitive and should not be used by hi-tech companies. Our R&D is now working on auto-reset function at OMC.

Why does communication equipment use -48V power instead of positive voltage?

History reasons are behind the use of -48V power. In early years, telephones were powered by telephone exchange through telephone line and the telephone lines undertook power transmission, voice transmission, ring current and pick I up/hang-on signals. Telephone exchanges used primitive lead-acid battery. Materials and equipment structure at that time were suitable for positive-pole grounding and the voltage was integral times of the basic voltage 1.2V. Limited by equipment and line capacity, the power supply used positive-pole grounding to achieve longer communication distance and higher safety. The voltage was +48V (sometimes +60V) and from the angle of ground, the system voltage is -48V. Telephone exchange has experienced magnet →Common battery →Automatic exchange (electromechanical, electrical)→ SPC switch. Power supplies of all the generations are compatible except magnet system and voltage and ground pole can remain unchanged. By such means, we can ensure that communication between old and new equipment is not interrupted and make direct exchange of information between them possible. Though new technologies and equipment keep coming out, update of communication system has to be gradual and compatible. This is not only a technical issue but also need of the society.

Four Common Tools

Signaling tracking: Service and NE compatibility analysis, used for find out faults

Failure value search: It helps us to know what kind of problem it is according to cause value of failed signaling.

Failure observation: It is used to detect bugs after commercial launch of system. Through failure observation, we can find any wrong configuration that can lead to complaints from subscribers.

No. 7 code stream analysis: It helps us to tell where problem lies according to analysis of ISUP and TUP messages between networks.

Product Concepts Engineering Operations

Service Flows Special Terms

Tone Play

Tone Configuration ： Please apply for tone version in advance if you need. R&D makes .tone files and tone configuration script according to your need. Tone configuration procedure:

Load tone script Configure tone data of MSCS in OMC. Configure tone data of MGW in OMC Configure service keys of tone board

Load tone files Tone play

Generally speaking, tone-play configuration does not need to be changed. If you do need to change tone-play of corresponding failure code type, you can change the playing code in the configuration of the corresponding failure code. As for tones that do not have failure code, such as call waiting, you can change Tone ID of playing code in “Tone Service Configuration”. Times and timing of tone-play can be changed in “Service Tone Playing Method” of MSCS.

How is LI achieved?

LIC is changed with registration and control of target subscribers. It monitors events of subscribers meanwhile collect, store, analyze and retrieve related data. Communication equipment sutmit subscribers’ events and service data according to instructions by LIC.

LIC uses X1 to carry out subscriber registration and control to related equipment. X2 is used to submit subscribers’ events to LIC. X3 is used to submit service data of target subscribers to LIC. X1 and X2 can be encrypted.

LIC imposes monitor on target subscribers in MSCS through X1. After MSCS sets control for the subscribers, it submits the message to LIC through X2. Once the target subscriber triggers any sensitive services, his/her events report and content of short messages will be reported to LIC through X2. X3 outputs contents of voice calls and data communication of target subscribers in a real-time fashion.

Procedure of Version Entry Application

Why “00” is needed at head of international number?

Format of international number is usually 00+CC+NDC+SN or 00+CC+areacode+SN, for example, 0086139 and 008625. Format of national number is usually NDC+SN or 0+area code+SN, for example 139XXXX and 025. Subscriber number and local number are usually SN, for example local number of Nanjing 52870001.

Domestic carriers and most of foreign carriers use the international prefix of “00” and national prefix of “0”. When subscribers make calls, numbers starting with “00” will all be seen as international and numbers starting with “0” will be seen as national and whether the call is allowed to proceed or not will be decided according to subscriber’s right. When subscribers receive international calls, they will most probably see “00+CC+NDC” or “00+CC+region code+SN” at the handsets.

The prefixes will also be used in service processing by MSC. In out WCN system, calling number analysis will be made first when subscriber calls international number. Usually we analyze “0” in local analyzer and rest of the number will be analyzed later. Then the other “0” will be analyzed in national long-distance analyzer and rest of the number will be analyzed later. CC will be analyzed in international long-distance analyzer. If the international number is legal (for example, US numbers that start with 001), MSC checks if the subscriber has the right for international call in VLR. If YES, the call can proceed. Otherwise, the call will be stopped and announcement will be played to the calling party.

How do special numbers (like 110) access?

Special service numbers like 110 and 119 access at the nearest station. CN needs to connect emergency calls originated from various location areas and cells to the nearest station. As the traffic stations are located in fixed telephone network, CN needs to connect the calls to different traffic stations according to positions of cells where subscribers are located. ZTE’s approach: ZTE identifies the nearest position through cells and use different numbers to access as the position varies. ZTE changes one same number through the means of special service group to achieves the nearest access of special services.

There are 2G and 3G access by type of wireless access Or direct connecting and connecting-after-change by type of traff

ic station accessed. For example, urban subscribers can be directly connected to urban traffic stations without number change while suburban subscribers should be connected to suburban traffic stations according to their positions. Here we take the access of 110 for example to explain access of special service numbers.

How alarm info is sent to the background

The alarm management system performs centralized monitor on the entire MSCS system. It gathers exceptional information from boards, links, DB and server in a real-time fashion. Once fault happens or any index goes beyond threshold, alarm will be issued.

Alarm information shows running status and performance of the system for troubleshooting.

Alarm clear means to eliminate an alarm from current alarm list and put it in history alarm DB when certain rules are met. This helps us to focus on more important alarms without missing less important ones.

Product Concepts Engineering Operations Service Flows

Special Terms

CS Interfaces (I) Mc: (G) It is the interface between MSC Server and MGW. Kind of

controlling signaling interface, it undertakes protocol interaction between MSC Server and MGW. It has the functions of controlling signaling for bearer establishment, resources management and gateway state management. It supports H.248/MEGACO.

A: It is the interface between MSC Server and BSS. MSC Server only handles control plane of Interface A. Its main functions are MM, BSS access, control plane processing for calls and SMS. It is based on E1 interface physically.

B: Internal interface between MSC and VLR C: It is the interface between MSC and HLR. MSC interacts with

HLR through Interface C when it requests for call routing. SMS-IG/GMSC interacts with HLR through Interface C when it requests for SM routing.

D: It is the interface between VLR and HLR. It is used to exchange location information, subscription information and current state of subscribers. When MS originates or receives call in service area, VLR provides location information of subscriber to HLR and provides roaming number to subscriber during the call. HLR sends service data to VLR.

CS Interfaces (II)

E: It is the interface between MSCs. When MS moves from one MSCS to another during a call, MSCS will perform HO to keep the call continuing so MSCs have to exchange data to each other.

F: It is the interface between MSC and EIR. It is used to exchange data between EIR and MSC Server when EIR conducts authentication to IMEI of MS.

G: It is the interface between VLRs. When MS moves from one VLR to another, previous VLR sends IMSI and authentication parameters to new VLR through the interface.

Nc: It is the interface between MSCs. Upon this interface call control between two networks is performed. Interface Nc can be realized by BICC protocol.

Nb: It is the interface between MGWs. It is charged with media stream transmission between MGWs. In case of ATM/IP bearer, Interface Nb establishes bearer channel through barer signaling protocol. Therefore, the interface consists of two parts, user plane and control plane.

Iu-CS: It is the interface between MSC Server and RNS. In R4, control plane and bearer plane are separated and MSC Server is only responsible for processing of control plane messages. Therefore, Iu-CS of MSC Server works on the control plane only. Its functions are MM, RNS access, control plane processing of calls and SMS. It is based o ATM and IP physically.

PS Interfaces (I) Gi: It is the interface between PLMN and external PDN. CN is

connected with external PDN through Gi. GGSN allows subscribers to access Internet through direct connection or NAT or visit internal server or terminals of enterprises through tunnel and VPN.

Gn, Gp: Gn/Gp is the interface between GSN nodes. Gn is the interface between GSN nodes of one PLMN and Gp is the interface between GSN nodes of two PLMNs.

Gs: Gs is an optional interface between MSCS/VLR and SGSN. Gs is used to coordinate interaction between MSCS/VLR and SGSN. SGSN achieves joint attachment, joint location update and joint deactivation through Gs. MSCS/VLR uses UMTS-PS connection to send paging and MM information through Gs interface. Gs realizes such functions as paging for non-UMTS-PS services, LU processing for non-UMTS-PS services, reminding service processing for non-UMTS-PS, UMTS-PS/IMSI detachment, reset, MM/MS info processing and error processing through BSSAP+ messages.

PS Interfaces (II)

Gc: It is the interface between GGSN and HLR. It is an optional interface and uses MAP protocol. It gets address of SGSN where MS is located during reverse PDP context activation so that PDP context activation originated by network can be achieved. No.7 signaling is used to bear Gc. If there is no Interface Gc, GGSN needs to get address of subscriber’s SGSN from the SGSN that has GTP-MAP conversion function through GTP during reverse PDP activation.

Gr: Gr is the interface between HLR and SGSN. It is used to exchange location information, GPRS information and current state of subscribers.

Gf: It is the interface between EIR and SGSN, used for data exchange between them when EIR performs authentication for IMEI of MS.

Iu-PS: Iu is the interface between MSCS/MGW/SGSN and RNC. The interface between MSCS/MGW and RNC is Iu-CS. The interface between SGSN and RNC is Iu-PS.

HLR Interfaces

H: It is the internal interface between HLR and AUC. It does not have standard protocol. When HLR receives authentication request from MS, HLR gets authentication data from AUC and send the data through Interface H.

Interfaces between HLR and MSC, GGSN and SGSN have been described before.

What is E1?

European standard of 30-line pulse code modulation PCM is called E1 and its rate is 2.048Mbit/s. China adopts the Europe definition of E1.

Length of one E1 frame is 256-bit, divided into 3 time slots, and one time slot has 8 bits.

8k E1 frames pass through E1 interface every second so the rate is 8K*256=2048kbps.

One time slot occupies 8bit in E1 frame, 8*8k=64k, so one E1 has 32*64K.

E1 frame structure: frame, unframed and multi-frame. In frame E1, TS 0 is used to transmit frame sync data and the other 31 time slots are used to transmit meaningful data.

Utilization of E1 in CN At present, V1 and ZXWN-V3 equipment all have E1 interface boards,

such as DTB and SPB. They all adopt frame mode of E1. One DTB provides 32 E1 interfaces. One SPB provides 16 E1 interfac

es.

Meanings of board lamps

ENUM: Independent from other lamps, it shows state of the jiggle switch.

ACT: ACT shows if any service is running at the board.

State ENUM state Meaning

Jiggle switch open Stay lit Board is not completely plugged in and

version has not been downloaded.

Jiggle switch alarm 5 Hz flash Switch is opened when board is running

Board can be unplugged

1 Hz flashSwitch is opened when board is running

but board is in standby state so it can be unplugged.

Jiggle switch OK Stay off Jiggle switch locked

State ACT state Meaning

Active Lit

No standby boardActive board of 1＋ 1 boards Active board or board whose resources ar

e active (for example, APS or optical port active) in case of 1: 1 boards

Standby Off Standby board of 1＋ 1 boards

ACT does not necessarily mean active/standby state. Long lit of ACT means the board is in active state only if the board works in 1+1 mode.

State of RUN and ALM and MeaningsState RUN state ALM state PRI Meaning

Initial state Lit Off 0 Initial state

Normal running 1 Hz flash Off 1 Normal running

Version download

5 Hz flash Off Booting Version downloading proceeding

1 Hz flash 5 Hz flash Booting Version download fails, board inconsistent with configuration, cannot download version

On Off BootingDEBUG download VxWorks successfully, wait for version download and run;RELEASE version means version download succeeds and version is being start

ed.

Self-check failOff 5 Hz flash 7 Board self-check fail

Off 2 Hz flash 8 Support startup fail

Fault alarm

5 Hz flash 5 Hz flash 9 Fail to get logic address

5 Hz flash 2 Hz flash 10 Basic process power-on failure or timed out

5 Hz flash 1 Hz flash 11 Fail to initialize core data area

2 Hz flash 5 Hz flash 6 Alarm of mismatch of version, hardware and configuration

2 Hz flash 2 Hz flash 2 Media-plane communication break

2 Hz flash 1 Hz flash 3 HW break

1 Hz flash 2 Hz flash 4 Disconnected with OMP

1 Hz flash 1 Hz flash 5 Active-standby changeover in process

Unchanged On 12 Loss of 8K, 16M hardware clock

Debugging state of board 1 Hz flash 5 Hz flash 13 Board enters debugging state, board does not restart when problem happens and

task is suspended.

Advantages and disadvantages of Over-large LAC

Advantage: Avoid frequent location update Disadvantage：

If LAC is too large, paging during call sometimes leads to overload in signaling channels of Interface A and overload of SDCCH, which will cause decline of paging success ratio. Also larger LAC has more subscribers and traffic volume will rise subsequently, which will also cause drop of paging success ratio.

Distribution of LAC is not continuous sometimes so subscribers need more location updates if the LAC is too large.

Advantages and disadvantages of Over-small LAC

Advantage ： Smaller LAC results in smaller paging area and also drop of traffic in L

AC and drop of Interface A load. Disadvantage ：

Smaller LAC will inevitably lead to rise of LU times. Too many registrations affect system capacity on one hand and shorten standby time of handsets on the other hand.

Smaller LAC means more neighbor location areas. If the arrangement of LAC areas does not perfectly conform with wireless coverage, wireless signals at boundary areas cannot be controlled strictly inside of their own paging areas. If a subscriber is in boundary area of LAC areas and inside paging area of LAC1 while signals of base station in LAC1 are very weak, his/her handset has to use the signals from base station of LAC2. As a result, the subscriber cannot be paged and paging response ratio declines.

Smaller LAC area affects flexibility of LAC boundary setting. LAC boundary should be set at positions where there are less subscribers to avoid affecting network indices due to coverage and signal problems in boundary area.

Difference of memory DB and physical DB of HLR

Physical DB: Physical DB uses ORACLE and is held at disk array of DB server at background. Background DB server adopts cluster and RAID technologies, using redundant arrays as storage equipment to hold user data. One DB server node is made of two HP 3440 servers and one disk array.

Memory DB: Memory DB is in memory of background DB server or foreground MP so that user data can be accessed quickly. Memory DB loads data from physical DB and we can regard it as backup of user data in memory. Memory DB can run in memory of DB server or foreground MP modules, depending on configuration. When HLR handles query services, it only needs to visit memory DB. When HLR handles mobile services, for example LU of 3G subscriber, the service-processing subsystem sends service request to memory DB to query and modify subscriber data. Change of subscriber data in memory data will all be synchronized to physical DB. When service provisioning server (DBIO) modifies data of mobile subscribers, it modifies the physical DB and the memory DB at the same time. If the modification fails, all operations will be rolled back, thus it can guarantee the conformity of subscriber data in physical DB and memory DB.

What is OMP used for?

Full name of OMP is Operation Main Processor and it is the maintenance agent of OMM Server. It holds configurations and version files of equipments and serves as information channel to OMM Server that transmits alarm and statistics information. In Version Management, version files of boards are loaded to OMP board so that other boards can download version files from OMP when they are restarted. OMP needs to create OMP guide file and configure OMP startup parameters through serial port to download its version files from OMC server.

Compare of DPC/GT addressing (I)

Mobile networks have two types of signaling addressing, DPC+SSN and GT+SSN. • GT means Global Title and it is usually intelligent network service number or ISDN. • Flexible routing with GT is a feature of SCCP. Unlike DPC, which works only in specific signaling network, GT is valid in global range and its address range is far larger than DPC. With GT addressing, we can transmit circuit-unrelated messages between any two signaling points in global range. However, SCCP needs to translate GT into DPC+SSN first and then pass the messages to MTP for transmission.• DPC is destination point code and GT is global title. SSN is subsystem number used to differentiate MSC/VLR and HLR. • DPC+SSN and GT are two addressing modes of SCCP. The difference is that DPC is the destination SPC used by MTP. SSN is the subsystem number used to tell SCCP users in one node.

Compare of DPC/GT addressing (II)

DPC+SSN Advantage: Directly use DCP to address in No.7 signaling networ

k so delay of message transmission is short. Disadvantage: SPC codes of all signaling points that have SCCP

signaling relation with it in the entire network need to be configured so the configuration data are huge in amount, making maintenance and management inconvenient

GT Advantage: We only need to configure SPC of SCCP STP (for exa

mple, SP of LSTP) and messages will be sent to SCCP STP where it will be transferred to destination.

Disadvantage: Delay increases every time message passes SCCP STP. Both addressing methods are used in our practice.

Relevant specification of GSM networks of domestic carriers: International, inter-province and intra-province SCCP messages adopt GT addressing (DPC+SSN addressing is used if there are direct links in the province.) SCCP messages between signaling points in one mobile network or two associated signaling points adopt DPC+SSN addressing.

What is HW?

HW-Highway

HW is the high-speed transmission channel in digital switch network. Rate of HW in out switch network is 8448kbit/s.

What are loop address, service address and real address?

Service address: SCTP processing address is configured at the loop interface of the RPU module and it corresponds to the IP address in SCTP configuration.

Real address: It is configured at SIPI and used for interconnection with CE.

Configure service address and real address at MSCS and MGW according to IP address planning of signaling services.