xsupercell_training-read for basics

7/31/2019 Xsupercell_training-read for Basics

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Rajeev Kumar Mishra


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Telephone Transmission

Line

2 Wire

Voice transmitted both directions simultaneously

Trunk

4 Wire

Voice transmitted both directions simultaneously (one way on each pair)

Connects switching center to switching center

Voice digitization and multiplexing

Analog voice waveform is sampled 8000 times per second

Each sample is converted into an 8-bit code

DS0 is a 64Kbit per second representation of 1 voice

DS1 multiplexes 24DS0s plus 1 sync bit onto a 1.5 Mbps highway

T1 is a US standard 4 wire trunk that carries 1 DS1 (24x64Kbps)

E1 is a CCITT standard 4 wire trunk that carries 32X64Kbps


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Base StationController

Switch

Public WiredPhone Network

(PSTN)1

0

Base Stations

SubscriberUnits

WirelineTelephone

Cellular Infrastructure

1

0

Typical Cellular Network


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Overview of SuperCell Architecture

Elements in the SuperCell System

Various Interfaces in the SuperCell System

Resources involved in a Call

Explanation about various cards in various elements in SuperCell

System

Basic Call flows

SuperCell Architecture


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Terrestrial

Circuit(PCM coded

uncompressed

digitized speech)

(CDMA Style)

OMC-R

Mobility Transcoder Base Mobile

Manager (XC) Transceiver Station

Mobile

Switching

Center

(MSC)(MM) Station

(BTS)

(MS)

Air Interface

BTS Span

(vocoded

compressed

digitized speech)

Landline Phone


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Mobile Switching Center(Switch) is a matchmaker between the cellular

system and the rest of the world, or between two subscribers within the

same cellular system. It is also an accountant keeping track of the subscribers

and their usage (bills).

Public SwitchedPhone Network

(PSTN)

Landline Phone

OMC-R



Mobile

Switching

Center

(MSC) (MM) Station(BTS)

(MS)

Air Interface

(CDMA Style)SuperCell Architecture


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The Mobility Manager (MM) is a dispatcher, controlling the flow of calls,

allocating channels, and keeping certain records. It is also responsible for

keeping track of all of the physical devices in the Base Transceiver Stations

and managing faults that occur in them.

OMC-R



Mobile

Switching

Center

(MSC)(MM) Station

(BTS)

(MS)

Air InterfacePublic SwitchedPhone Network

(PSTN)

SuperCell Architecture(CDMA Style)

Landline Phone


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The Transcoder (XC) is primarily interpreter translating between two forms of

digitized speech: the Mobile Stations vocoded compressed speech,

and the uncompressed PCM format of the Mobile Switching Center

and the Public Telephone Network.

OMC-R



Mobile

Switching

Center

(MSC)(MM) Station

(BTS)

(MS)


(PSTN)


Landline Phone


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The Base Transceiver Station (BTS) (also called the Base Station or the Cell

Site) is a radio station that conveys messages and voice between the Transcoder

and the Mobile Station. The Base Transceiver Station transmits and receives on

channels of two types:

1:) a Traffic Channel (TCH) which is used for voice or data and

2:) a Paging and Access Channel (PG-ACC) which is used for call setup.

OMC-R



Mobile

Switching

Center

(MSC)(MM) Station

(BTS)

(MS)

Air Interface


(PSTN)


Landline Phone


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Operations & Maintenance Center - Radio (OMC-R)

Manages Configuration, Fault, Event, and Performance data

OMC-R



Station

(BTS)

Mobile

Switching

Center

(MSC)(MM) (MS)


(PSTN)

OMC-R

Centralized Base Station

Controller (CBSC)

Mobile

Party


Landline Phone


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Concentration

on A+ Trunks

(Typically 3:1)

Voice & Data

Integrated Internally

same T1/E1 Span

POOLED

VOCODERS

4:1 Compression

on BTS Spans

T1/E1Spans

Transcoder

Mobility

Manager

WAN

OMC-R

SC-UNO

SC-UNO

Ability to RemotelyLocate OMC-R andSC-UNO Platforms

Cell

Site

Fiber Optic Token Ring

Ethernet

T1/E1Spans

Span intf.

Span intf.

Cntrl.

Switching

Matrix

CBSC

V.35 For A+ Control Links

DSU

XCDRS

MobileSwitching

Center

Cell

Site

Cell

Site

CDMA Base Station System(BSS)

Interconnections


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(PSTN)

MSC

MMXC

CBSC-1

BTS BTS BTS BTS

XC MM

CBSC-2

OMC-R

= Voice

= Control

Scap/LAPD

Scap/LAPD

NECA/J7 RNMP/TCP/IP

CMIP

Mobile Switching Center

Transcoder MobilityManager

Centralized BaseStation Controller

T1 or E1transmissionfacility

JE1 or T1transmissionfacility

Operations &MaintenanceCenter - Radio

BaseTransceiverStation

x-term x-term

UserInterface

GraphicalUser Interface

BTS

or A+/SS7

Scap/LAPDSTRAU/16kb

PCM/64kb

STRAU/16kbCBSC SHO

Inter

Working

Unit

= Data/Fax

SMAP

UNO Universal

Network Operations

IWU



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Major Elements in the SuperCell System

MSC

CBSC

BTS

OMC-R

UNO

MM

XC

GLI

MCC

BBX


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MSC

Billing Records.

Subscriber DatabaseHard Handoff.

A+ to CBSC.

PSTN, HLR interfaces.


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MM(Mobility Manager)

A+ Interface to MSC

Handoff ArbitrationBTS Fault Management.

Channel Allocation

Page Distribution

BTS Init.& Download


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XC(Transcoder)

QCELP Transcoding

Switching Function

Mobile Event Detect.

Signaling on the TCH

Paging Distribution

Soft handoff handling


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XC- GPROC(Gnereic Processor)

Front-End Processor(FEP GPROC): This processor

routes control traffic between the XC devices, BTs, and

the MM. It converts between LAPD and TCP/IP so theMM can talk to the BTSs.

Operations & Management Processor(OMP GPROC):

This processor is the master GPROC for the XC

subsystem-it performs operations andmaintenance(O&M), fault management, and device state

management for all the devices in the XC.

Call Processing Processor(CPP GPROC): Carries out

orders dictated by MM for channel allocations and call


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XC-XCDR(Transcoder Card)

Performs the transcoding functionality of XC

Performs selector and inband traffic channel signallingmessage generation and termination functions.


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Operations

and

Maintenance

Processor

OMP

GPROC

Call

Processing

Processor

CPP

GPROC

Front End

Processor

FEP

Multiple

Serial

Interface

2-T1 or E1

MSI-

Multiple

Serial

Interface

2-T1 or E1

MSI-

Kilo-Port

Switch

KSW

Trans-

coder

XCDR

Generic

Clock

GCLK

Redundant 1024 x 64 kbps Time Division Multiplex Busses

Redundant Token ring LANs

Redundant

MCAP

Busses

OMC MM

DSU

MSCBTS BTS

T1

T1 or E1

T1T1

V.35

MCAP is Motorolas Advanced Processor Bus - extends to all cards on a single shelf

Token ring is extended to all GPROCs on ALL shelves

Data Service Unit (DSU) converts serial data from high speed V.35 interface to a single DS0 (64kbps) - bi directional

Kilo-Port Switch is a non-blocking time slot interchanger that can circuit switch 8, 16, 32, or 64 kbps

Voice PathVoice Path


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Operations

and

Maintenance

Processor

OMP

GPROC(2)

Call

Processing

Processor

CPP

GPROC

Front End

Processor

FEP

Multiple

Serial

Interface

2-T1 or E1

MSI-2

Multiple

Serial

Interface

2-T1 or E1

MSI-2

Kilo-Port

Switch

KSW

Trans-

coder

XCDR

Generic

Clock

GCLK

Redundant 1024 x 64 kbps Time Division Multiplex Busses

Redundant Token ring LANs

Redundant

MCAP

Busses

OMC MM

DSU

MSCBTS BTS

T1

T1 or E1

T1T1

V.35

NCON/BTSLINK is a nailed up connection (called Cell Site LAPD link (CSLDL) in XC)

Each FEP may terminate up to 10 BTSLINKs

Inter FEP routing allows messages from one BTS to be routed to another BTS or to the CPP GPROC

Paging is supported by group addresses

MM to BTS Control Path


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BTS-GLI(Group Line Interface)

Acts as a controller to the BTS

Routes the control and bearere traffic to variousdevices

Connected to all other cards via

CHI(Concentrated highway interface) bus


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BBX(Broadband Transceiver)

The BBX converts digital baseband signals to RF for

the Forward(transmit) link and RF to digital baseband

signals for the reverse links.

The BBX is controlled by the Group Line Interface

card via the CHI bus.


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BTS- MCC(Multi-Channel CDMA Card

Traffic Channels

Power Control

Signal QualityMeasurements

Signaling on page & access channels

Softer Handoff


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Mobile Originated Phone Call

Step 1 - Customer turns on Mobile Station, dials digits, and presses SND.

Step 2 - Mobile Station searches for strongest Base Transceiver Station

(BTS) signal and sends message to BTS. Message includes the

customers directory number, the serial number of the Mobile

Station, the dialed digits and the authentication data(for data/fax calls).

Step 3 - BTS acknowledges receipt ofMobile Stations message.

Step 4 - BTS passes Mobile Stations request on to the Mobility Manager.

Step 5 - Mobility Managerpasses Mobile Stations request on to the Mobile

Switching Center.

Step 6 - MobileSwitching Centerselects a Terrestrial Circuit to carry the call

and forwards the circuit identification to the Mobility Manager.

Step 7 - Mobility Managerforwards Terrestrial Circuit identification to

Transcoder.


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Step 8 - Mobility Managerselects a Traffic Channel (MCC and CE) and

a Walsh Code to carry the call and orders the Transcoderto

connect a transcoder circuit to the selected BTS and Traffic

Channel.

Step 9 - Transcodersends message to the selected BTS telling it which

Traffic Channel and Walsh Code to use.

Step 10 - BTS starts transmitting on Traffic Channel and sends message to

Mobile Station telling it which Walsh Code to receive.

Step 11 - Mobile Station starts receiving and transmitting on Traffic

Channel.

Step 12 - Transcoderdetects communication with Mobile Station and

sends acknowledgement to Mobile Station.

Step 13 - Mobile Station acknowledges back.



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Step 14 - Transcoderorders Mobile Station to switch to voice mode and start

QCELP coding.

Step 15 - Mobile Station starts vocoding and sends acknowledgement

message to Transcoder.

Step 16 - Transcoderconnects chosen terrestrial circuit to transcoder circuit

and sends message to Mobility Managersaying that radio connectionwas successful.

Step 17 - Mobility Managersends message to Switch saying that radio

connection was successful.

Step 18 - MobileSwitching Centertells Mobility Managerthat ringing isgoing on and provides ringback tone on terrestrial circuit for

customer to hear.

Step 19 - When called party answers, MobileSwitching Centersends

connect message to Mobility Manager.


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MSC MM XC PG-ACC TCH MS

[1] ORIGINATION MESSAGE

MIN: "My directory number is ..."ESN: "My serial number is ..."DIALED DIGITS: "I want to call ..."

[2] BASE STATION ACKNOWLEDGMENT ORDER

"Message Received"

[3] CHANNEL REQUIRED (ORIGINATION MESSAGE)

[4] CALL MANAGEMENT SERVICE REQUEST (Dir Num,ESN..)

"I have a call coming in - use this SCCP ID to reference it"

[5] CONNECTION CONFIRM

[6] SETUP (DIALED DIGITS)

Switch will now use dialed digits to route call to destination"

[7] CALL PROCEEDING

[8] ASSIGNMENT REQUEST (TERRESTRIAL CIRCUIT ID)

"Use this terrestrial circuit (span and timeslot) to carry the voice for this call"

CDMA SUCCESSFUL Origination - Mobile to Land with Mobile

disconnect


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[9] CHANNEL ASSIGNED (MSID,ESN, CE, WC, SO...)

[MM selects XCDR circuit Channel Element (CE) and Walsh Code (WC)][Channel Element includes both MCC card id plus CE(1-24) on MCC][Connect TERCKT to XCDR to channel Element]

[10] CHANNEL ASSIGNED (MSID,ESN,CE, WC)

"Start to transmit null traffic channel data''

[11] CHANNEL ASSIGNED (MSID, WC...)

[12] CHANNEL ASSIGNMENT (MSID,WC...)

"Listen for this Walsh code (Language)

and start sending "traffic channel preamble""

[13] TCH Preamble

"Sync up"[14] [Invalid speech STRAU]

[STRAU is SuperCell Transcoder Rate Adaption Unit"-a XC to CE protocol]'

[XCDR detects CE acquisition of the MS]

[15] Suspend TCH Assignment


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[16] BASE ACKNOWLEDGE

"Base Station has acquired Mobile on traffic channel"

[17] MOBILE ACKNOWLEDGE

"Received Acknowledge"

[18] SERVICE OPTION RESPONSE ORDER

"Start vocoding - transmit and receive speech"

[19] MS ACKNOWLEDGE ORDER

"Ok"

[20] XC TERRESTRIAL CIRCUIT ASSIGNMENT

"Connect this terrestrial circuit to XCDR circuit"

[21] XC ASSIGNMENT SUCCESSFUL

"Ok. Voice is now on the BTS - XC link"


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[22] ASSIGNMENT COMPLETE

"Switch will now output (send) dialed digits into network (PSTN)"

[23] ALERTING

[Actually could be a variety of call progress tones such as:'

Busy, Fast Busy, Tri-tone "this number is no longer in service" or ringback]

[ringback tone from MSC to MS (in traffic channel) ]

[24] CONNECT

"Called party has answered, transmit voice on terrestrial circuit and

start charge timing"

*** Conversation begins ***

[25] CONNECT ACKNOWLEDGE

"Ok"

*** Mobile party disconnects (hangs up) ***

[26] RELEASE ORDER [Normal Mobile Release]

[27] RELEASE ORDER

[Confirm]


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MM XC PG-ACC TCH MS

[28] XC RADIO CHANNEL RELEASED

[Releases terrestrial circuit, Channel Element, and XC resources]

[29] RELEASE

"Mobile has hung up - Stop charge timing"

[30] RELEASE COMPLETE

[31] CLEAR COMMAND

"Release terrestrial circuit"

[32] CLEAR COMPLETE

"Its all over"

[33] RELEASE RADIO CHANNEL

[34] RADIO CHANNEL RELEASED

[now ready for reassignment]


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CDMA SUCCESSFUL TERMINATION - Land to Mobile with Land disconnect

[1] PAGING (MSI,Slot cycle index, Paging Area)

[2] PAGE(MIN,SO)

[Page is sent to all paging/access channelsService Option (SO) is always 1 for voice]

[3] (Slotted)PAGE MESSAGE(MIN, SO)

[4] PAGE RESPONSE (MSID, SO)

"Im here-this is the Service Option that I want"'

[5] BASE STATION ACKNOWLEDGEMENT ORDER

"Ok"

[6] PAGE RESPONSE (MSID,BTS/Sector, SO)

[7] PAGING RESPONSE (BTS/Sector, MSID)

"I have found the party you asked for - use this SCCP ID to reference the call"

[8] CONNECTION CONFIRM + SETUP

[9] CALL CONFIRMED



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[10] ASSIGNMENT REQUEST (TERRESTRIAL CIRCUIT ID)

[MM allocates XCDR, MCC and Channel Element]

[11] TCH ASSIGNED (TERCKT ID, CE, WC...)

"Connect TERCKT to XCDR to Channel Element"

[12] TCH ASSIGNED (CE, WC...)

"Start to transmit nulltrafficchanneldata'"'

[13] TCH ASSIGNED (MCC, CE, WC, SO...)

[14] TCH ASSIGNMENT (WC...)

"Listen for this Walsh code (Language)

and start sending trafficchannelpreamble'"'

[15] TCH Preamble

"Sync up"[16] [Invalid speech STRAU]

[ XCDR detects CE acquisition of the MS]

[17] SUSPEND TCH ASSIGNMENT


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[18] BASE ACKNOWLEDGE

"Base Station has acquired Mobile on traffic channel"

[19] MOBILE ACKNOWLEDGE

"Your acknowledgement received"

[20] SERVICE OPTION RESPONSE ORDER (SO...)

"Start vocoding - transmit and receive speech"

[21] MS ACKNOWLEDGE ORDER

"Ok"

[22] ASSIGNMENT SUCCESSFUL

"Ok Voice is now on the BTS - XC link"

[23] ASSIGNMENT COMPLETE

[24] ALERT WITH INFORMATION(Unique Alert)

"Ring the mobile in the way indicated"


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[25] ALERT WITH INFORMATION(Unique Alert)

*** Mobile now ringing -- assume Mobile answers ***

[26] CONNECT ORDER

[Mobile stops ringing, and starts vocoding - XC starts vocoding]

[27] BASE STATION ACKNOWLEDGEMENT ORDER

"Ok"

[28] XC CONNECT

[29] CONNECT

"Mobile has answered, conversation has begun - start charge timing"

[30] CONNECT ACKNOWLEDGE

*** Assume Land party disconnects ***

[31] RELEASE

[Switch will stop charge timing]


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[32] XC RELEASE RADIO CHANNEL

[33] RELEASE ORDER

[34] RELEASE ORDER

[XCDR detects loss of MS - returns silence]


[36] RELEASE COMPLETE

[37] CLEAR COMMAND

[38] CLEAR COMPLETE

[39] RELEASE RADIO CHANNEL


MSI = Mobile station identity (phone number)(BCD)MIN is binary version of MSIMSID = (MIN , Electronic Serial Number(ESN))Each MS has a unique ESN, several can share a MSI


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FDMA (frequency division multiple access) is the division of the frequency band

allocated forwirelesscellular telephone communication into 30 channels, each of

which can carry a voice conversation or, with digital service, carry digital data.

FDMA is a basic technology in the analog Advanced Mobile Phone Service (AMPS

), the most widely-installed cellular phone system installed in North America. WithFDMA, each channel can be assigned to only one user at a time. FDMA is also used

in the Total Access Communication System (TACS).

The Digital-Advanced Mobile Phone Service (D-AMPS) also uses FDMA but adds

time division multiple access (TDMA) to get three channels for each FDMA

channel, tripling the number of calls that can be handled on a channel.

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