cdma technique and its special function

8/10/2019 CDMA Technique and Its Special Function

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IJCST VOL. 3, ISSUE1, JAN. - MARCH2012ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)

w w w . i j c s t . c o m INTERNATIONALJOURNALOFCOMPUTERSCIENCEANDTECHNOLOGY 291

Abstract

The CDMA refers to such a technology that the transmitting end

modulates the signals that it sends using mutually different and

(quasi) orthogonal pseudo-random address codes, and the receiving

end detects the corresponding signals by demodulating the mixed

signals using the same pseudo-random address codes. In this paper

we discuss its special function in network technology.

Keyword

Network Diagram of CDMA, 123 Call Flow, 123 IVR Call Flow,

Network Design of SCP Interface Server

I. Introduction

A. Minimized the Required of the Transmission Media

In telecommunication network transmission media is very precious.

CDMA network elements (e.g. MSC/VLR,SMSC(Short Message

Service), HLR,SCP) are connected via dedicate E1(PCM) links

for signaling (CCS7), which is very vulnerable or low redundancy

. If link is break network element goes aloof.

To avoid this kind of situation all the network elements are

connected to SSTP(Stand Alone Signal Transfer Point) which main

function is transfer the signaling of network element through single

E1 or PCS link, no need to connect all the network elements to each

other. Like in BSNL West Bengal circle has one SSTP at Kolkataand mated pair in Bihar circle Patna SSTP. All the CDMA MSCs

in west Bengal, SCP, PDSN,SMSC, all Transit Exchanges (TAX)

are connected to SSTP Kolkata as primary signaling transfer point

and SSTP Patna as secondary or redundancy of rst one.

B. Network Diagram of CDMA Network Elements Before

SSTP Connectivity

Fig. 1: CDMA Network Diagram

In g. 1, all MSCs are connected individually to other CDMA

network elements like SCP,HLR, SMSC,PDSN. Total no. of E1or PCMs requirement is eleven.

If we connect all the CDMA network elements to SSTP then

requirement of PCM is very less.

C. Network Diagram of CDMA Network Elements After

SSTP Connectivity

In g. 2, describe that all the CDMA Network Elements like

MSCs, HLR, PDSN, SMSC are connected to SSTP network. All

signaling is transfer though SSTP, it reduced the requirement of

E1 or PCM. If new network element connects to CDMA network,

we just require single PCM.

Fig. 2: CDMA Network Diagram with SSTP

II. 123 IVR (Interactive Voice Record) Announcement for

Roaming Pre-Paid Subscriber

A. 123 Call Flow Of Home Subscriber

STEP 1

This scenario describes call origination by a home subscriber

dialing 123.Pre-Paid subscriber of CDMA gets announcement

123 for balance enquiry, recharge etc. When subscriber in home

location, dialing 123 call forward to own MSC.

STEP 2MSC query to its HLR. In HLR subscriber status is Pre-Paid

so MSC send the signaling message to SCP with MDN(Mobile

Directory Number) via ORREQ signaling. SCP check the

subscriber status in SCP Server whether subscriber has active?

Blacklisted (unauthorized subscriber )/missing Claim ? if all are

OK, then SCP check dial no. 123.

STEP 3

SCP send the SIZZER signaling message to IP(Intelligent

Peripheral play announcement for 123 ) for allocating the free

resource for announcement which called TLDN(Temporary

Located Directory Number ).

STEP 4

IP send the free TLDN no. to SCP via SIZZER Response Signaling.

After SCP get the free TLDN no. from IP ,its send to originating

CDMA Technique & Its Special Function inNetwork Technology1Sanjoy Paul, 2Radha Krishna Jana

1JTO, CDMA Nodal Centre, Kolkata, WB, India2Dept. of CSE, Mallabhum Institute of Technology, Bishnupur, Bankura, WB, India


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IJCST VOL. 3, ISSUE1, JAN. - MARCH2012 ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)

w w w . i j c s t . c o m292 INTERNATIONALJOURNALOFCOMPUTERSCIENCEANDTECHNOLOGY

calling MSC via CONNECT signaling. MSC collect TLDN no. from

SCP and contact to IP directly for getting announcement. After IP

getting TLDN no. from MSC which is match with allocated TLDN

to SCP, then IP send INTREQ(Instruction Request) signaling to

SCP for requesting which announcement to play.SCP sent SRFDIR

signaling with announcement no. from its announcement list.

After getting SRFDIR signaling with announcement no. IP play

announcement to subscriber and send SRFDIR RES signaling to

SCP to conrm successful announcement.

B. 123 IVR Call Flow of Home Subscriber

Fig. 3:

C. Signalling Flow for 123 IVR

Fig. 4:

An MS call origination with dialed digits is received by the1.

Serving MSC.

The Serving MSC detects and sends an ORREQ signal to2.

the SCP.

The SCP determines that an IP is required to play an3.

announcement to the MS with the subscribers. The SCP

sends a SEIZERES to an IP requesting the resource.

When the IP receives the SEIZERES, it allocates a TLDN to4.

the appropriate resource. The TLDN is returned to the SCP

in the seizeres.

The SCP sends a CONNRES to the Serving MSC with5.

instructions to set up a call leg to the IP.The Serving MSC

sets up the call leg to the IP.

When the call is detected at the IP, the IP sends an INSTREQ6.

to the SCP requesting call processing instructions.

The SCP sends an SRFDIR to the IP with the ANNLIST7.

parameter indicating the announcement to play.The IP plays

the announcement indicated by the ANNLIST parameter.

The IP sends an empty srfdir to the SCP.8.

The SCP sends an instreq to the IP to conclude the SCP-IP9.

conversation.

Note: the SCP may send the instreq to the IP at any time after

Step-f.The SCP determines the subscriber has Pre-Paid active and the10.

subscribers account is active. The SCP sends an orreq to the

Serving MSC to indicate that call processing shall continue

D. 123 Call Flow of Roaming Subscriber

But when subscriber in Roaming then scenario is something

different because visited MSC not directly connected to IP or

SCP. Different MSCs connected to different SCP and IP.

Like in BSNL CDMA Network Elements divided into three zone

like east zone, west-north zone, south zone.In east zone two SCP

and two IP and under east zone SCP and IP total 17no. MSCs.

Let Pre-Paid subscriber of east zone roaming into other MSC ofother zone (west-north or south zone), visited MSC or serving MSC

not directly connected to east zone SCP or IP .where subscriber dial

123 for balance enquiry, call routed to visited MSC which have no

data(location update) for new subscriber. Then visited MSC query

to HLR. HLR send the subscriber data from its data base to visited

MSC via SSTP which contain the subscriber type, SCP location,

SMSC location etc. Visited MSC check the database, if it is pre paid

subscriber then it send the MDN and dial no. to SCP which location

known from its HLR data base via ORREQ signaling. SCP check

the subscriber status in SCP Server whether subscriber has active?

Blacklisted (unauthorized subscriber)/missing Claim? If all are

OK, then SCP checks dial no. 123. SCP send the SIZZER signaling

message to IP(Intelligent Peripheral play announcement for 123) for allocating the free resource play announcement which called

TLDN(Temporary Located Directory Number ). IP send the free

TLDN no. to SCP via SIZZER Response Signaling. After SCP

get the free TLDN no. from IP, its send to originating calling MSC

via CONNECT signaling. MSC collect TLDN no. from SCP and

contact to IP directly for getting announcement. After IP getting

TLDN no. from MSC which is match with allocated TLDN to

SCP then IP sends INTREQ (Instruction Request) signaling to SCP

for requesting which announcement to play. SCP sent SRFDIR

signaling with announcement number from its announcement list.

After getting SRFDIR signaling with announcement number IP

play announcement to subscriber and send SRFDIR RES to SCPto conrm successful announcement.


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IJCST VOL. 3, ISSUE1, JAN. - MARCH2012ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)

w w w . i j c s t . c o m INTERNATIONALJOURNALOFCOMPUTERSCIENCEANDTECHNOLOGY 293

E. 123 IVR Call Flow In Roaming Scenario for East Zone

Subscriber

Fig. 5:

Subscriber Dial 123.1.

Roaming MSC send to WIN SCP Kolkata for validation.2.

WIN SCP check and send WIN IP for 123 calling.3.

WIN IP send TLDN no.(11Digit) to SCP .4.

SCP send TLDN no. to Roaming MSC.5.

Roaming MSC dial with TLDN no. provide by IP via L16.

Tax.

WIN IP Kolkata play announcement to Roaming Subscriber7.via Roaming MSC.

III. Network Design of SCP Interface Server Connectivity

with M/s Pyro for Cnannel Top-up or Recharge for BSNL

EAST ZONE Pre-paid Subscriber

Fig. 6:

E1 Converter ,it converts TCP/IP link to PCM link.

SCP IMP Server is Interface Server of CDMA Network.

SCP Subs. DATABASE ,Where subscribers data store.

When prepaid subscriber wish to recharge his/her number though

easy, c-topup or through web (www.bsnl.co.in/recharge). His

request send to M/s Pyro server with proper denomination(rupees

value) and validity in day. In Pyro server check authentication

of subscriber pay account through payee Bank. After successful

payment of recharge value subscriber , pyro server re commands

to SCP IMP server with proper value and validity. Then SCP

subscriber data Base is update with new validity and recharge

sum amount.

Here Pyro server and SCP server not co-located so both network

connected via PCM. But servers are working with TCP/IP network.

So here E1 converter required to convert PCM or E1 to TCP/IP

or vis. Versa.

Router required here to aggregate the both Pyro network and

SCP network. Because both are use different network address.

R outer also provides securities to CDMA network from Pyro

network. It is very important thing to this network other wise any

intruder can access the subscriber Data Base which content thewhole BSNL EAST Zone pre-paid subscribers data with CDR(call

Detail Record).

IV. SCP O&M Client (SMAP Client) Extended to Different

MSC in EAST ZONE Via E1 Converter

SMAP or Service Management Access Point ,through which SCP

services like subscriber creation, issue, deletion, modication

system up gradation are manage. SCP is zonal equipment, so every

circle need SMAP client to manage its own circle subscribers.

SMAP server is located in Kolkata for east zone. To extended the

client to different circle required two E1 converter which convert

TCP/IP link to E1 link or vise versa for each circle. A router ofcisco series is provides to aggregate the client network and SCP

network because both has different network IDs. Output port

of router connected to switch. From switch E1 converters are

connected by RJ45 cable and via E1 link or PCM link connection

is extended to different circle. Each circle use same E1 converter

to convert PCM or E1 link to TCP/IP link. Remote SMAP client

connected to converter by RJ45 cable. Flowing schematic diagram

describe the whole scenario of network connection.

Fig. 7:


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IJCST VOL. 3, ISSUE1, JAN. - MARCH2012 ISSN : 0976-8491 (Online) | ISSN : 2229-4333 (Print)

w w w . i j c s t . c o m294 INTERNATIONALJOURNALOFCOMPUTERSCIENCEANDTECHNOLOGY

References

[1] Theodore S. Rappaport,"Wireless Communications Principle

& Practice", 2nd Edition, PHI.

[2] Tata Mc-Graw Hill B. A. Rorouzan,"Data Communication

and Networking", 3rd Edition.

[3] William Stalling,"Wireless Communications & Network",

Pearson Education.

[4] Andrew, S.Tanenbaum,"Computer Networks", Fourth

Edition.

[5] W.C.Y. Lee,"Mobile Communications Engineering".

Sanjoy Paul received his Bachelor

of Engineering in Electronics and

Communication Engineering from

Burdwan University, India, in 2004,

pursuing M.Tech degree in Microwave

Engineering from Birla Institute of

Technology, Mesra, Ranchi, India, in

2012. He presently working as Junior

Telecom Ofcer in Wireless Intelligent

Network, Kolkata project in BharatSanchar Nigam Limited (A Govt. of

India Enterprise) .

Radha Krishna Jana received his

B.E. degree in Computer Science

and Engineering from Bribhum

institute of Engineering and

Technology,Sur i ,Birbhum,West

Bengal,India in 2004, the M.Tech. degree

in Computer Technology from Jadavpur

University, Jadavpur,Kolkata, in 2008. He

was a lecturer, Senior lecturer, assistantprofessor, with Department of Computer

Science and Engineering,Mallabhum

Institute of Technology, in 2006, 2010 and 2010 respectively. Now

he is also assistant professor with department of Computer science

& Engineering in Mallabhum Institute of Technology His research

interests include Database Management System, GIS & Remote

Sensing, Articial Intelligence and Wireless Communication.

cdma technique and its special function

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