Issue 05/01 Slide 1.1
Oscilloquartz SA
The Synchronisation of
Telecommunications Networks
Issue 05/01 Slide 1.2
Oscilloquartz SA
Contents
Contents
I. The Need for Synchronisation
II. Characterizing Synchronisation Quality
III. Synchronisation Distribution: General Principles
IV. Synchronisation Distribution: SDH/SONET-based
Solution
1. Elements
2. Architecture
3. Synchronisation Status Message (SSM)
V. Synchronisation Distribution: GPS-based and
MixedSolution
I. The Need for Synchronisation
II. Characterizing Synchronisation Quality
III. Synchronisation Distribution: General Principles
IV. Synchronisation Distribution: SDH/SONET-based
Solution
1. Elements
2. Architecture
3. Synchronisation Status Message (SSM)
V. Synchronisation Distribution: GPS-based and
MixedSolution
Issue 05/01 Slide 1.3
Oscilloquartz SA
Contents

5. Optical Networks
6. GSM and UMTS-FDD Radio Access Networks
7. cdmaOne and cdma2000 Radio Access Networks
Issue 05/01 Slide 1.5
Oscilloquartz SA
Abbreviations
Abbreviations
» ADM Add Drop Multiplexer
» ATM Asynchronous Transfer
Mode
» BITS Building Integrated Timing
Supply
» bit/s bits per second
1kbit/s = 1,000 bits/s
1Mbit/s = 1,000,000 bits/s
1Gbit/s = 1,000,000,000 bit/s
» CBR Constant Bit Rate
» CDV Cell Delay Variation
» DNU Do Not Use
» DXC Digital Cross-Connect
» f frequency
» FIFO First-In First-Out
» GPS Global Positioning System
» GUI Graphical User Interface
» HSC High Stability Clock
» ADM Add Drop Multiplexer
» ATM Asynchronous Transfer
Mode
» BITS Building Integrated Timing
Supply

» PLL Phase Locked Loop
» Hz Hertz (cycles per second)
1mHz = 0.001Hz
1 µHz = 0.000001Hz
» ITU International Telecommunications
Union
» k kilo = 1,000
» LOS Loss Of Signal
» LT Line Terminal
» MTIE Maximum Time Interval Error
» NE Network Element
» OC-N Optical Carrier level N
» OS Operating System
» p pointer
» PABX Private Automatic Branch
Exchange
» PDH Plesiochronous Digital Hierarchy
» PEC Plesiochronous Equipment Clock
» PLL Phase Locked Loop
Issue 05/01 Slide 1.6
Oscilloquartz SA
Abbreviations
Abbreviations
» PRC Primary Reference Clock
» ps/km/°C pico seconds per kilometre
per degree centigrade
» QL Quality Level
» QOS Quality Of Service
» s second
1ms = 0.001s

» SETS Synchronous Equipment Timing
Source
» sin Sine function
» SOH Section OverHead
» SONET Synchronous Optical Network
» SRTS Synchronous Residual Time
Stamp
» SSM Synchronisation Status Message
» SSU Synchronisation Supply Unit
» STM-N Synchronous Transport Module
level N
» STS-N Synchronous Transport Signal
level N
» TF Transfer Function
» TIE Time Interval Error
» TS0 Time Slot Zero
» VBR Variable Bit Rate
» VCO Voltage Controlled Oscillator
» VC Virtual Container
» VT Virtual Tributary
» VTG Virtual Tributary Group
» UN Undefined
» W Wander
» w radians per second
» d variation
» SSM Synchronisation Status Message
» SSU Synchronisation Supply Unit
» STM-N Synchronous Transport Module
level N
» STS-N Synchronous Transport Signal

A
T
B
= 1 / f
B
f
A
= f
B
Issue 05/01 Slide 1.9
Oscilloquartz SA
Phase synchronisation
Phase synchronisation
System A
t
t
Clock signal of system A
Clock signal of system B
System B
!
!!
Issue 05/01 Slide 1.10
Oscilloquartz SA
Time synchronisation
Time synchronisation
System A
t
t
Time signal of system A
Time signal of system B

Synchronous Multiplexing
30 x 64 kbit/s 1 x 2.048 Mbit/s
Multiplexer
30
1
2
1 2
30
Issue 05/01 Slide 1.13
Oscilloquartz SA
Public Switched Telephone Network:
Space-Time Switching
Public Switched Telephone Network:
Space-Time Switching
Switch
1 2 3 54 6
1 2 3 54 6
N x 2.048 Mbit/s N x 2.048 Mbit/s
Issue 05/01 Slide 1.14
Oscilloquartz SA
What is a slip?
What is a slip?
» A slip occurs when a buffer over- or
underflows due to differences in timing
» A slip occurs when a buffer over- or
underflows due to differences in timing
Incoming data rate
Outgoing data rate
Slip
Slip

» Slips will reduce transmission throughput
Issue 05/01 Slide 1.16
Oscilloquartz SA
Slip rate due to frequency deviation
Slip rate due to frequency deviation
» Slip rate = fractional freq. dev / frame
duration
» For 2 Mbit/s signals, frame duration =
125 microseconds :
»10
-11
= 1 slip in 4.8 months
»10
-10
= 1 slip in 14.5 days
»10
-9
= 1 slip in 1.45 days
»10
-8
= 6.9 slips per day
»10
-7
= 2.9 slips per hour
»10
-6
= 28.8 slips per hour
»10
-5
= 4.8 slips per minute

Oscilloquartz SA
SDH/SONET Transport Networks:
Nominally Synchronous Multiplexing
SDH/SONET Transport Networks:
Nominally Synchronous Multiplexing
63 x E1 1 x STM-1
Multiplexer
63
1
2
OH 1 2 63
Issue 05/01 Slide 1.19
Oscilloquartz SA
Wander induced by pointer activity
Wander induced by pointer activity
t
TIE of E1 signal
t
TIE of E1 signal
PRC
NE
NE
NE
SDH/SONET Network
ADM
E1
ADM
E1
Synchronisation distribution
trails affected by wander

BTS
BTS
Successful handover requires synchronisation between
base transceiver stations (BTS)
Issue 05/01 Slide 1.22
Oscilloquartz SA
Cellular Mobile Telecom Networks
Cellular Mobile Telecom Networks
Radio carrier frequencies must be synchronized precisely
in order to prevent cross-talk
Radio spectrum
Frequency
Issue 05/01 Slide 1.23
Oscilloquartz SA
Characterizing
Synchronisation Quality
Characterizing
Synchronisation Quality
Issue 05/01 Slide 1.24
Oscilloquartz SA
Definition of jitter : ITU-T Rec. G.810
Definition of jitter : ITU-T Rec. G.810
 The short term variations of the significant
instants of a digital signal from their
reference positions in time
 Greater than 10Hz in modulation frequency
 The short term variations of the significant
instants of a digital signal from their
reference positions in time
 Greater than 10Hz in modulation frequency