tran_pln

8/12/2019 TRAN_PLN

1/24

NOKIA smart.PPT / 18.01.1999 / page: 1

Transmission Network Planning

I. Planning ModulesII. Synchronisation

8/12/2019 TRAN_PLN

2/24


The telecommunication networkBasic physical infrastructureTransport Network

Access Network

Network Management System

Planning modules/process

Network AssessmentNetwork Dimensioning

Detailed Network Planning

BenefitsComplete solutions

Qualified personnel

Cost efficiency

Technology transfer

I. Network Planning Process

NMSCellular

F ixed

access

Data

access

Cellular

access

IN

Cabl ing & Infrastructure

Transpor t Network

PSTN Data

8/12/2019 TRAN_PLN

3/24


Planning process (step one)

Network Assessment:

Traffic Matrix/Distribution

Network Capacity Utilisation

Existing Access Network

Interfaces within the network

Geographical Study

Equipment Analysis

Input:

Business IdeaRegulationsExisting InfrastructuresNetwork DiagramsSpecial Solutions

Network Dimensioning

Network AssessmentOutcome of the NetworkAssessment

Services to be supported by the

network

Quality requirements

Market segmentation and location

Network hierarchy and topologyalternatives

Spare capacity recommendations

Routing principles

Recommendation for technology

decision and equipment selection

Advantages and restrictions

of existing network to be taken into

account

Advantages and restrictions

of existing network

8/12/2019 TRAN_PLN

4/24


Planning process (step two)

Network Dimensioning

Network Dimensioning:

Network architecture (flat/layered)

Rollout plan

Protection principles

Capacity planning on transmission links

Cross-connection requirements

Management and

Synchronisation principlesEquipment lists (rough)

Cost Optimisation


Input :

Quality requirement

Capacity requirement

Growth estimates

Network Dimensioning Outcome

Rollout plan

Network diagrams where shown needed

capacities and cross-connection level

Protection requirements

Management & Synchronisation

principles

Equipment lists

8/12/2019 TRAN_PLN

5/24NOKIA smart.PPT / 18.01.1999 / page: 5

Planning process (step three)


Detailed Network Planning:

Detailed network diagram

Protection planning

Management planning

Channel Allocation planning

64kbit/s Cross-Connection planning

Synchronisation planningRoute calculations

(Optical/radio link budget)

Input :

Re-evaluated network

dimensioning input

information

Detailed Network Planning ensuresthe

information which is accurate enough for

network implementation.

Mount

4 3 1 7 4 3 7 1 95 0

7 9% /02 631963 47358

9 3 % / us

F il e E di t L oc at e V ie w H el p

1 2 3 4 5 6 70

100

200

300

400

500EDCBA

NetworkTraffic Help

Network Implementation

8/12/2019 TRAN_PLN


II. Synchronisation Planning

8/12/2019 TRAN_PLN


Why synchronisation is important ?

If the node clocks in a telecommunication network operate asynchronously

then the transmit and receive rates of the telecommunication systems in eachnode would be different to the other node. In this case, the input buffers of thetelecommunication systems would frequently overflow which will cause dataerrors commonly referred to as slips.

In SDH network, the lack of a common timing reference increases the number

of pointer operations. A large number of pointer operations can lead toexcessive jitter and wander in the payload signals carried by an SDH network.

In order to limit the number of pointer operations by SDH nodes- thus avoidingslips and errors- all the node clocks and hence all the telecommunicationsystems should be synchronised to the same master clock.

8/12/2019 TRAN_PLN


Optimal synchronisation and timingof a mixed PDH & SDH network

Synchronisation in PDH networks

Synchronisation in SDH networks

Synchronisation delivery for upper layers and in mixed PDH

& SDH networks

Example:

Cellular transport network

Conclusions

8/12/2019 TRAN_PLN


PDH networks for PSTN

Asynchronous connections betweendigital exchanges

2/8,34,140 Mbit/s muxes

fully timing transparent

Transport network mainly point-to-pointconnections

Synchronisation handled at theexchange

140M34M

8M

2 Mbit/s

34M8M

2 Mbit/s

Digital exchange Digital exchange

8/12/2019 TRAN_PLN


In SDH network synchronisationmaster slave principle is used with SSM

G.811PRC

G.812SSU

G.812SSU

G.812SSU

G.812SSU

G.812SSU

G.812SSU

G.812SSU

G.812SSU

G.812SSU

Transit

Local

SSM = Synchronisation Status Message

(SSU = Synchronisation Supply Unit)

Primary Reference Clock

8/12/2019 TRAN_PLN


Additional equipment

G.811

accuracy 1*10-11

61 ns rearrangement

Caesium-beam

+accurate

expensive

"Borrow" from another network+cheap

dependent on otheroperator

GPS + SSU

+relatively cheap

+SSU provides frequencyduring outage

PRC (Primary Reference Clock)

8/12/2019 TRAN_PLN


Additional equipment

Used to refresh timing andprovide hold-over

G.812 (slave clock)

holdover accuracy 5*10-10

+ 1*10-9/day (transit)

1 us rearrangement

Rubidium

accurate

limited lifetime

Advanced quartznot as accurate asRubidium

longer lifetime

SSU (Synchronisation Supply Unit)

8/12/2019 TRAN_PLN

13/24


Synchronisation reference chain in SDH

K

8/12/2019 TRAN_PLN

14/24


Subnetworks

Dividing a network into subnetworks makesthe network manageable

It also makes synchronisation planning easy

Protecting paths can be arranged

PRC PRC

Subnetwork 1

Subnetwork 2

8/12/2019 TRAN_PLN

15/24


Chain is the basic building block SSM (Synchronisation Status Messaging)

enables the synchronisation of different network architecture: Point topoint, chain, ring, mesh

It also provides the means of synchronisation protection which isseparate from telecommunication protection.

SEC SEC SEC

SEC = SDH equipment clock

G.811 G.812

G.811 G.811 G.811

DNU = Do Not Use

DNU DNU DNU

Direction of synchronisation

8/12/2019 TRAN_PLN

16/24


SSM enables changing direction

When a connection is broken, the rest of the network receives synchronisation fromthe other direction

SSM contains clock quality marker which enables the network to use the bestavailable clock to synchronize the network

G.811 G.812

A failure between two nodes

SEC SEC SEC

DNU

G.812G.812

Direction of synchronisation

DNU

8/12/2019 TRAN_PLN

17/24

8/12/2019 TRAN_PLN

18/24


Synchronisation planning

Master-slave synchronisation method

Priority tables for each node

Use of SSM enables all network topologies tobe protected

Timing loops are avoided by carefulsynchronisation planning

8/12/2019 TRAN_PLN

19/24


Example Cellular transport network (core)

PSTN

Core transportnetworkMSC

BSC BSC

Access network

Access network

MSC

BSC

Example Cellular transport network

8/12/2019 TRAN_PLN

20/24


Example Cellular transport network(access)

BSC

BTS

BTS

BTS

BTSBTS

BTS

BTS

BTS

BTSMicrowave radio(n * 2Mbit/s)

CopperHDSL

STM-1 (or STM-4)access network

8/12/2019 TRAN_PLN

21/24


Synchronising MSC

Timing traceable to PRC

GPS/SSU

Another network(if it can be relied on)

Caesium

Monitoring recommended

Rubidium

GPS

PSTN Caesium

PRC

Monitor

MSC

SDH

sync

8/12/2019 TRAN_PLN

22/24


Timing is not affected

by pointers

Synchronising BSC

External synchronisation interfaces(SDH node out, BSC in)or

2 Mbit/s with re-timing

SDH2 Mbit/s

and

2 MHz synch. interface

BSC

SDH

2 Mbit/s with re-timing

BSC

8/12/2019 TRAN_PLN

23/24


Synchronising BTS

2 Mbit/s with retiming

2 Mbit/s(w/o retiming)

pointer tolerance must be verified inadvance

end of synchronisation chain(distribution only to other BTS)

External synchronisation interfaces

(SDH node out, BTS in)

SDH

BTS

2 Mbit/s with or without

re-timing

SDH

BTS

2 Mbit/s

and2 MHz synch. interface

8/12/2019 TRAN_PLN

24/24


Conclusions

Select the primary source (PRC) for timing carefully

Move over to SDH based synchronisation distributionas soon as possible (when SDH coverage available);equipment must support SSM (for controlled synchr. protection)

Do not use a synchronous 2 Mbit/s network for synchronisation of largeSDH networks (reference quality control)

Wander performance important (ITU-T Rec.G.823, ETS 300 462-3)

Synchronisation planning is done with care to avoid timing loop

Synchronisation provides not only error free transmission betweendifferent interfaces but also frequency reference to Base stations.

tran_pln

Documents