Telecom Basics ppt

MONTH 08, 2015

Telecom Basics

HARMAN International. Confidential. Copyright 2015. 2

1. GSM - Divisions

2. Structure of GSM Network

3. GSM Network Elements

4. CDR

5. Mediation

6. Rating and Charging

7. Billing

AGENDA


8. Billing

9. Feed back


GSM

GSM stands for Global system for Mobile is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second-generation (2G) digital cellular networks used by mobile phones.

• 1G• 2G• EDGE (Enhanced Data Rates for GSM Evolution) • 3G (UMTS – Universal Mobile Telecommunication systems)• 4GLTE(Long term Evolution)• 5G (R&D – Future)


In the GSM system, the network is divided into the following partitioned areas. • GSM service area• PLMN service area• MSC service area• Location area• Cells.


GSM service area - is the total area served by the combination of all member countries where a mobile can be serviced.

PLMN service area - There can be several within a country, based on its size. The links between a GSM/PLMN network and other PSTN, ISDN, or PLMN network will be on the level of international or national transit exchange. All incoming calls for a GSM/PLMN network will be routed to a gateway MSC. A gateway MSC works as an incoming transit exchange for the GSM/PLMN. In a GSM/PLMN network, all mobile-terminated calls will be routed to a gateway MSC. Call connections between PLMNs, or to fixed networks, must be routed through certain designated MSCs called a gateway MSC.

GSM and PLMN Service area


MSC/VLR service area- In one PLMN there can be several MSC/VLR service area. MSC/VLR is a role controller of calls within its jurisdiction. In order to route a call to a mobile subscriber, the path through links to the MSC in the MSC area where the subscriber is currently located.

LA’s - There are several LA’s within one MSc/VLR combination. A LA is a part of the MSC/VLR service area in which a MS may move freely without updating location information to the MSC/VLR exchange that control the LA. Within a LA a paging message is broadcast in order to find the called mobile subscriber. The LA can be identified by the system using the Location Area Identity (LAI). The LA is used by the GSM system to search for a subscriber in a active state. It is present in the SIM

MSC/VLR and LA


Cellular – Network technology that breaks geographical area into cells shaped like honey comb.

Cells – Cell is the radio coverage of one base transceiver station.

Cellular Structure

12

34

567

67

215


Structure of a GSM Network


GSM + GPRS

NSS

BTS+BSC BSS

ME+SIM MS

MSC

HLR

VLR

AuC

EIR

SGSN

GGSN

SMS -GMSC

INTERNET

G-msc

PSTN


MS: To transmit and receive voice and data over the air interface of the GSM system. • MS performs the signal processing function of digitizing, encoding,

error protecting, encrypting, and modulating the transmitted signals.• It also performs the inverse functions on the received signals from

the BS.• IMEI- International Mobile Equipment IdentitySIM : Static Information -International Mobile Subscriber Identity(IMSI)• Personal Identification Number (PIN)• Authentication Key (Ki)• Dynamic Information - Temporary Mobile Subscriber Identity(TMSI)• Location Area Identity (LAI)• Phone memories, billing information• Ability to store Short Messages received

Mobile station


• Handles the radio interface to the mobile station.• Consists of one or more radio terminals for transmission and

reception• BTS and MS communicates over Um interface• Received data transcoding• Voice encryption/decryption• Signal processing functions of the radio interface

Base Transceiver Station


• Provides all the control functions and physical links between the MSC and BTS

• External Interfaces‘Abis’ interface towards the BTS

‘A’ interface towards the MSC• Monitors and controls several BTSs• Management of channels on the radio interface• It also reallocates frequencies to the BTSs in its area to

meet locally heavy demands during peak hours or on special events. The BSC controls the power transmission of both BSSs and MSs in its area.

Base Station Controller


• The main function of the MSC is to coordinate the set up of calls between GSM mobile and PSTN users. Specifically, it performs functions such as paging, resource allocation, location registration, and encryption.

• It also serves as a SMS gateway to forward SMS messages from Short Message Service Centers (SMSC) to the subscribers and from the subscribers to the SMSCs. It thus acts as a message mailbox and delivery system.

Mobile Switching Center


The HLR is a database that permanently stores data related to a given set of subscribers. The HLR is the reference database for subscriber parameters. Various identification numbers and addresses as well as authentication parameters, services subscribed, and special routing information are stored. Current subscriber status including a subscriber’s temporary roaming number and associated VLR if the mobile is roaming, are maintained. • The HLR provides data needed to route calls to all MS-SIMs home based in its MSC area, even when

they are roaming out of area or in other GSM networks. • It provides the current location data needed to support searching for and paging the MS-SIM for

incoming calls, wherever the MS-SIM may be. It also holds the VLR ID in which MSC user has latched.

• It is responsible for storage and provision of SIM authentication and encryption parameters needed by the MSC where the MS-SIM is operating. It obtains these parameters from the AUC.

• It maintains record of which supplementary service each user has subscribed to and provides permission control in granting services.

• The HLR stores the identification of SMS gateways that have messages for the subscriber under the SMS until they can be transmitted to the subscriber and receipt is knowledge.

• Some data are mandatory, other data are optional.

Home Location Register


• A MS roaming in an MSC area is controlled by the VLR responsible for that area.

• The VLR constitutes the databases that support the MSC in the storage and retrieval of the data of subscribers present in its area.

• To avoid load(Number of queries) on HLR, VLR is replica of HLR and acts as Temporary DB.

• Whenever user latch in new area MSC, the VLR updates the location and all profile information from HLR.

• In VLR, in which MSC user currently latched in that VLR the location will update.

• DB contains IMSI,TMSI,MSISDN,LA, MSRN, Authentication key.• Actual location will be in VLR. The exact cell in which MS is located.

Visitor Location Register


• The AUC stores information that is necessary to protect communication through the air interface against intrusions, to which the mobile is vulnerable

• Stores Subscriber authentication data called Ki, a copy of which is also stored in in the SIM card

• Generates security related parameters to authorize a subscriber (SRES-Signed RESponse)

• In the authentication procedure, the key Ki is never transmitted to the mobile over the air path, only a random number is sent. In order to gain access to the system, the mobile must provide the correct Signed Response (SRES) in answer to a random number (RAND) generated by AUC

• Generates unique data pattern called Cipher key (Kc) for user data encryption

• The HLR is also responsible for the “authentication” of the subscriber each time he makes or receives a call. The AUC, which actually performs this function, is a separate GSM entity that will often be physically included with the HLR.

Authentication Center


• EIR is a database that stores the IMEI numbers for all registered ME units. The IMEI uniquely identifies all registered ME.

• White List: contains those IMEIs that are known to have been assigned to valid MS’s. This is the category of genuine equipment.

• Black List: contains IMEIs of mobiles that have been reported stolen.

• Gray List: contains IMEIs of mobiles that have problems (for example, faulty software, wrong make of the equipment). This list contains all MEs with faults not important enough for barring

Equipment Identity Register


• Mobile SubscThe MSISDN is a GSM directory number which uniquely identifies a mobile subscription in the Public Switched Telephone Network (PSTN).

• Calls will be routed from the PSTN and other networks based on the subsribers’ MSISDN number.

MSISDN= CC + NDC + SNCC= Country Code (91)NDC= National Destination Code(98370)SN= Subscriber Number (12345)

Subscriber Identity MSISDN


• New bearer service to GSM that gives improved and simplified wireless access to Packet data networks.

• GPRS Applies packet radio principle to transfer user data packets in an efficient way between MS and external PDN (Packet Data Network)

• GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible:

• SMS messaging and broadcasting• "Always on" internet access• Multimedia messaging service (MMS)• Push to talk over cellular (PoC)• Instant messaging and presence—wireless village• Internet applications for smart devices through wireless application protocol (WAP)• Point-to-point (P2P) & P2M services

GPRS – General Packet Radio Service


• In aspect of functionality, is equivalent to GMSC• Interface between GPRS network and external packet switched networks• The GGSN converts the GPRS packets coming from the SGSN into the appropriate

packet data protocol (PDP) format (e.g., IP ) and sends them out on the corresponding packet data network. In the other direction, PDP addresses of incoming data packets are converted to the GSM address of the destination user. The readdressed packets are sent to the responsible SGSN. For this purpose, the GGSN stores the current SGSN address of the user and his or her profile in its location register.

GGSN – Gateway GPRS Supporting Node


• It is responsible for the delivery of data packets from and to the mobile stations within its geographical service area.

• Its tasks include packet routing and transfer, mobility management (attach/detach and location management), logical link management, and authentication and charging functions.

• The location register of the SGSN stores location information (e.g., current cell, current VLR) and user profiles (e.g., IMSI, address(es) used in the packet data network) of all GPRS users registered with it.

• Common functions are :• Detect & Register new GPRS MS in its serving area• Authentication and maintaining user profiles• Deliver data packets to Mobile station and vice versa.• Billing user data

SGSN – Service GPRS Support Node


• A data collector in the network switch captures the usage in the form of Call Detail Record (CDR)/Usage Detail Record (UDRs). These raw CDRs/UDRs are in turn converted by the mediation system into a format understandable by the Billing System.

• Example: MSC, SMSC, GGSN, MMSC• There could be different network elements controlling the services and

producing different types of CDRs; for example, for GSM telephony:Voice calls are captured by the MSC (Mobile Switching Centre).SMS traffic is captured by the SMSC.Data traffic is captured by the GGSN.MMS traffic is captured by the MMSC.Roaming CDRs are captured by roaming partner's switching element.

CDR – Call Detail Record


Ericsson\1AM0650.aut

sample_cdr.txt

CDR's.csv

..\Desktop\INSERTDB_20121130105711_2819.txt

Sample CDRS and Parsed CDRS

Ericsson/1AM0650.aut

sample_cdr.txt

CDR's.csv

../Desktop/INSERTDB_20121130105711_2819.txt


CDR consists of • Date timestamp• A Number calling party• B Number Called Party• Usage – duration • Sequence number• In route – The call routed to B number• Out Route – The call routed from A number• In Switch• Out Switch• Record Type – Determines Which type of call

CDR Attributes used for Rating & Charging


• It the mediator between Network switching systems and Billing system. Not only Billing system the other down streams like Fraud Management, Revenue Assurance systems

• Mediation collects the CDRs from the network elements (MSC, SGSN, GGSN etc) • It converts the ASCII, Binary formatted records generated by the switches

(MSC,GGSN,SMSC etc) to understandable billing system language to Rate, charge and finally Invoice the records

• Mediation can filter the calls (CDRS like ineffective (Zero duration calls)) at Mediation end itself.

Mediation


User should be rated and charged on the service he opted to use. Services like Voice, SMS, DataIn general, service is created in the application (For few products , Billing system itself has CRM, for few CRM will different product itself). Eg: customer pays 99$ to use 1GB DataEg: Telefonica Movistar_IDD, corporate_375_priceplan etcTariff Plan: Tariff associated to avail the service is Tariff plan. It describes the price, the destination, dial code and currency. Tariff plan can configured in the Billing system using Rating sheets. Sample Rate sheet as shown below:Eg:

Rating and Charging

Destination

Dial code Price/min currency

Pune 0221234 30 INR


• Once Tariffs are configured in the system, We need to creating Matching criteria to Match the CDRS and Rate them.

• In general, Traffic scenarios are created and Matching criteria are configured in the Traffic Scenarios.

• In TCB, Rate is configured in Rate rule and not in Rate plan. Rate rule and Price plan has same Rate plan. In Rate rule, Input and Output matching criteria are configured

• Based on the CDR attributes, we can configure in the Rating Engine , which attribute needs to be checked and once matched it can be rated.

• Eg: We can do rating on B number available in the CDR or just based on the Route or Trunk in the CDRs.

• To perform such rating, we need to make sure everything (Like B numbers, Routes, Tariff )has been configured properly in our Billing System.


• If there is any configuration mistake or any improper CDR has sent to Billing system, it will put all of such CDRS in Suspense.

• Suspense should be cleared before Billing.• Same Route might be configured for cash flow in and cash flow out. Few

operators hold the routes for both cash flows. • Each subscriber should be billed with different kind charges like, One time

charge and Recurring charging, Bi monthly charging. Based on those charges, we can do billing as well in similar way like Monthly Billing, Bi Monthly Billing


Each operator (in case interconnect) and subscriber (Retail billing) holds the Bill profile, it describes the type of the bill should be generated like (ITFS bill, Bilateral bill, Hubbing bill, statements)They have service associated to each Bill profile and tariffs are part of the service while configuring the Bill profile. Bill cycle – Indicates the duration of the usage to be billed. Bill cycle can be Monthly and Bi monthly. It means 01st of every month to last day of the month usage will be billed in Monthly cycle. 01st of every month to mid of the month i.e. 15th of every month is said to be Bi monthly. What is the significance of Bill Cycle Date (BCD) in TCB?• All subscription services/bundles (ie. minutes, SMS, KB) are reset tomaximum amount• All recurring charges for new bill cycle (ie. monthly services/bundles) are charged against each subscription that belongs to a particular account• Invoice is generated for each account

Billing


Avinash Puli

[email protected]

Feed back


Thank You

Telecom Basics ppt

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