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www.huawei.com
Adam P. Grodecki
Solution Manager
Are You Ready to Syntonise? LTE advanced transmission
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Agenda
Basic concept of syntonisation
Incoming and Present Requirements
Huawei Solutions highlights
Summary
1
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So many information, how to organize them?
How to communicate ?
Packet Synchronization
IP clock
Stratum 1
ITU.T G.811
ITU.T G.812
ITU.T G.813
Stratum 2
Stratum 3
IEEE 1588vX
NTP
PNTP ITU.T G.823
ITU.T G.825
Phase Synchronization
Frequency Synchronization
ITU.T G.8262
ITU.T G.8261
ITU.T G.8263
Synch.E
Squelching Y.1362
retiming
SSM
IEEE 802.3x
ptp
ACR MTIE
1pps
ToD
ubx
nmea PRC
SSU
SEC 50ppm
IEEE 802.16D/e
ESMC
TDEV
cesium
rubidium
quartz
ITU.T G.8265
BC/TC/OC
ITU.T G.707, G.704
BMCA
ITU-T G.709, G.810, G.811, G.812, G.8261, G.8262, G.8264
TTT GMP(GE) BMP (10GE)
GFP-T
GFP-F
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The Purpose of use Accuracy
Defines how stable is the clock
Can be measured as Time Interval Error.
TIE can be processed into
drift plots showing MTIE or TDEV
Those can be compared
to desired masks (ex. ITU G.825)
and clasified as:
PRC (in practice often stratum1, ITU.T G.811)
SSU (in practice often stratum2, ITU.T G.812)
SEC (in practice often stratum3, ITU.T G.813)
Transport Defines how transport the clock
and what information to carry.
Can use physical interfaces or
packets for input and output.
Its’ quality has direct impact on
accuracy for the whole network.
It is defined in many standardizations,
that is why has to be always
challenged for Interoperabilities.
Aim is to syntonize or synchronize
oscilators of all NE.
SDH, fE1,Synchronous Ethernet
PTP, 1pps, 2MHz, 2048 kbps, ToD
Monitoring
Defines how devices exchange
information about its’ clock quality.
Use to make decision about source of
synchronization
Very important to know if quality of the
clock in the network is still according
to the design.
Very often manually overwriten to avoid
Interoperabilities issue – can cause
long term undiscovered problems.
SSM, squelching, ESMC(G.8264), BMCA
1588v2 delay req/resp
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The Key to organize is the Purpose of use?
Accuracy Transport Monitoring
Packet Synchronization
IP clock
Stratum 1(ANSI/T1.101)
ITU.T G.811 ITU.T G.812 ITU.T G.813
Stratum 2 Stratum 3
IEEE 1588vX
NTP
PNTP
ITU.T G.823 ITU.T G.825
Phase Synchronization Frequency Synchronization
ITU.T G.8262 ITU.T G.8261
ITU.T G.8263
Synch.E
Squelching Y.1362
retiming
SSM
IEEE 802.3x
ptp
ACR
MTIE 1pps
ToD ubx nmea
PRC SSU SEC
50ppm
IEEE 802.16D/e ESMC
TDEV
cesium rubidium quartz
ITU.T G.8265
ITU G.8275, G.8275.1
BC/TC/OC
ITU.T G.707, G.704 BMCA
ITU.T G.991.2
TTT GMP / BMP
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Other way to place the standard – ITU-T based
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ITU-T Packet Sync. Standards Architecture
ITU.T chose BC/OC for PHASE, G.8275.1 – finishing now
G.8275.2 – new profile discussion just starting – „partial on path suppport ”
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What are the network element capabilities?
Internal Oscilator cesium
rubidium quartz
Stratum 1
ITU.T G.811 ITU.T G.812
ITU.T G.813
Stratum 2 Stratum 3
Internal Logic
Input
Output
PRC SSU
SEC Node
HoldOver
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Clock Synchronization Working Modes basics
Free Running Mode
No available reference clocks.
or reference clocks become
unavailable.
Fast Tracking Mode
Node obtains reference clocks.
or reference clocks become
available but the phase offset
overtop the threshold.
Locked Mode
Node obtains reference clocks
and the frequency offset is
less than locked threshold.
or reference clocks in holdover
mode become available and
the phase offset is less than
frequency offset threshold.
Holdover Mode
When reference clocks become
unavailable.
or phase offset or frequency
offset overtop the locked
threshold.
Cold Startup Warm Startup
Free
Running
Locked
Fast
Tracking
Holdover
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Phase, time and frequency understanding
Watch A
Watch B
Frequency Synchronization
Phase Synchronization > Syntonisation
Watch A
Watch B
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Via IP – is it really make any sense ?
Precise Network Time Protocol (called PTP or 1588v2) ( ITU.T or IEEE )
transmitting Phase and Time information.
GPS, GLONASS or Beidou(CNSS)
utilization is weather dependant and reaquire clear sky acces.
PTP can be used in two architectual cases :
- End to End (TC, ACR)
- Hop by Hop (BC-BC,OC/BC)
LTE advanced (TDD, MBSFN) and MIMO require Phase information to be implemented.
ex. ETSI - TS 125.105
for the TDD mode there is the additional requirement for the phase alignment of neighboring base stations to within 2.5 µs
3GPP TS 25.402 - phase difference of the synchronization Signal shall not exceed 2.5 μs
Task:
What is relative time travel between radio
nodes that are located with 1km distance
(using 1800 MHz)
1000m/299.792m/µs ~3,3 us
ITU.T 6275.1 conclude for maximum ~4 us of phase difference (SG15 Plenary Meetings’ report)
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PTP - Basics
～
PRC
～
MAC
PHY
Ethernet PTP
IP
UDP
PTP
MAC
PHY
Ethernet
PTP
IP
UDP
PTP
PRC
1588 Master 1588 Slave
Hardware
timestamp
System Clock
PLL
System Clock
PLL
PTP packet Server packet
～
Protocol layer
Physical layer
Protocol layer
Physical layer
Protocol layer
Physical layer
1588v2 (also call PTP: Precise Time Protocol )
is based on protocol layer, the clock signal(1588v2
timestamp)
is carried by Ethernet or UDP/IP packet ;
As the 1588v2 timestamp is generated by hardware
between the PHY and MAC,
and this is very close to physical layer,
there is almost no protocol stack delay variability,
the timestamp is very stable,
so the protocol stack delay
variability will not affect 1588v2 synchronization
accuracy in hop-by-hop scenario;
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PTP - messages The protocol defines Event and General PTP messages.
Event messages: are timed messages in that an accurate timestamp is generated both at
transmission and receipt. Event messages are used to synchronize the time or frequency
form master to slave;
General messages: do not require accurate timestamps.
The Announce message is used to establish
the synchronization hierarchy.
Event messages General Messages
1, Sync
2, Delay_Req
3, Pdelay_Req
4, Pdelay_Resp
1, Announce
2, Follow_Up
3, Delay_Resp
4, Pdelay_Resp_Follow_Up
5, Management
6, Signaling
Master Slave
t1
t2
t3
t4
Timestamps
known by
slave
t1,t2
t1,t2,t3
t1,t2,t3,t4
Delay_Req message
Sync message
Delay_Resp message
Follow_Up message
*2way 2step example
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Agenda
Basic concept of syntonisation
Incoming and Present Requirements
Huawei Solutions highlights
Summary
2
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Wireless Standard Requirement on
Frequency Synchronization
Requirement on
Phase Synchronization
GSM/UMTS 0.05ppm see next
WCDMA 0.05ppm NA
TD-SCDMA 0.05ppm +/- 1.5us
CDMA2000 0.05ppm +/- 3us
WiMax FDD 0.05ppm NA
WiMax TDD 0.05ppm +/- 1us
LTE FDD 0.05ppm see next
LTE TDD 0.05ppm +/- 1.5us
Current Requirements status
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More detalis for Requirements status
Application Frequency sync. requirement
Phase sync. requirement
Standard ref.
UMTS 3G Standard +/-50ppb Not required R4(25.402)
DFCA/IBCA inter cell +/-50ppb +/-3.5us R8 / vendor specific
LTE FDD +/-50ppb Not required R8
eMBMS +/-50ppb +/-1.5us R9
Network MIMO Not defined yet, under 3GPP discussion
Not defined yet, under 3GPP discussion
R10/R11(LTE-A)
ICIC/eICIC +/-50ppb +/-1us R8
COMP Not defined yet, under 3GPP discussion
Not defined yet, under 3GPP discussion
R10/R11(LTE-A)
Location service (OTDOA) +/-50ppb +/-0.1us R9
Location service (other than OTDOA)
+/-50ppb +/-0.2us R9
*DC and Financial real time transaction and DVBT requirements are not considered above
Have you consider to sell Syntonization as a Service?
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Cases
Multicast Broadcast Single Frequency Network
Synchronous Transmission, Signal combing
Reduced interference, High SINR
Cell 1 Cell 2
Cell edge overlap in
MBSFN area
If syntonized
TV
Moving to cell edge
GuardBand
Two MNO have neighboring spectrum
If they are syntonized – they can alling frames in
TDD scheme
Can save even 4MHz spectrum for each MNO
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How to read RAN requirements (IBCA example)
Accuracy and stability is 10.67us/3day
The BTS spacing must be less than 1.5 km on the GSM 900 MHz network or less than 1.2 km on
the GSM 1800 MHz network.
Upper node of each BTS must be better than 16ppb
Clock source of all BTSs must be locked to the same clock source
or no frequency offset occurs among them
Network-wide synchronization must be achieved
Intermittent disconnections must be less than once a month for single-BTS transmission,
and the ALM-26262 Clock Reference Abnormal Alarm must be generated less than once a month.
SSM protocol of ITU-T G.8264 should be activated in all transmission devices.
The essence of using OOB
Fits in the MTIE/TDEV ITU Y G.825 masks
Drift not more than 3.55 us a day
Signalisation processing is a must
Do not ignore physics
16ppb = ∆t/period * bilion (ppb)
Maximum drift of 16ns in 1 ms
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Agenda
Basic concept of syntonisation
Incoming and Present Requirements
Huawei Solutions highlights
Summary
3
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PTP – Hop-by-Hop
BC BC
BC BC
BC BC
Clock Master
PRC
Each NE running as BC
Each Physical interface processing up to 1024 PTP packets per second to guarantee good quality of synchronization
Each BC exchanges with its neighbour PTP delay request and respond packects, These packets analysis is baseline for NE to lock on this clock source or not (using BMCA)
Working and backup paths are manually initiated by configuring priority list (...DNU)
Hop-by-hop allows to transport Phase, Time and Frequency
The Clock Master can retime from 2MHz into PTP Oscilators Syntonization
Frequency working path
Frequency backup path Phase working path Phase backup path
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PTP – End to End
Transmission is going through 3rd party network Maximum 128 PTP packets per second are exchanged Customer NE exchanges with Server PTP delay request and respond packects, These packets analysis is baseline for NE to lock on this clock source or not Must meet floor PDV parameters
Working and backup paths are manually initiated by configuring priority list
End to End limited to Frequency only
Oscilators Syntonization!!
Server 1
Client
Clock Master
PRC
Server 2
Frequency working path
Frequency backup path
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PTP – What is ToD and 1pps
Each device that tend to carry synchronization of Phase and Time consists of 2 additional interfaces: - ToD - 1pps
ToD can work in ASCII(nmea) or Binary(ubx) mode and exchange Time of Day information.
1pps interface is meant to provide/exchange 1 peak per second signal with accuracy at level of single ns.
Those interfaces are very usefull if RAN device require Phase and Time information but don’t understand PTP technology, it is another type of retiming scenario for PTP synchronization.
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Hybrid solution purpose Ease of intergration with existing networks lead to use hybrid solution.
Nothing special may think but most of existing hardware support only one mode at one time (either SynchE. or 1588v2)
Huawei can do both at the same time.
Is it possible to retime at end point to E1?
PRC
PRTC
PRC
PRTC
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Synchronization – unique1588 based
Huawei MW solution
Out-of-band OC/BC
In-band, E2E Phase and Frequency
Phase and Frequency Synchronization
Unaffected by link asymmetry
Unaffected by congestion of data traffic
Delay adjustment
In-band Traffic
Out-of-band OC/BC
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DWDM must be synchronized as well
xWDM
Principle is to regenerate bit stream tact
along with services delivered between
tributary interfaces,
In Carier Grade Solution it must
process signalization, alarm and monitor
directly on xWDM node as is Network Element
Several Mechanizms exist to perform that:
TTT GMP(GE), BMP (10GE)
GFP-T
GFP-F
Many standardisation are describing in details:
ITU-T G.709, G.810, G.811, G.812, G.8261, G.8262, G.8264
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DWDM can be syntonized as well
Each NE running as BC
Each BC exchanges with its neighbour PTP delay request and respond packects, These packets analysis is baseline for NE to lock on this clock source or not (using BMCA)
Working and backup paths are manually initiated by configuring priority list (...DNU)
Hop-by-hop allows to transport Phase, Time and Frequency
The Clock Master can retime into PTP
In xWDM Correction of NE Delay Imparity is very important to guarantee system preciseness
Clock Master
PRC
Oscilators Syntonization
NE
BC
NE
BC
NE
BC
NE
BC
PRTC
NE
BC
NE
BC
Frequency working path
Frequency backup path Phase working path Phase backup path
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Any Media - Phase Synchronization Monitoring Industry 1st clock visualization: Frequency / time deviation monitoring
Automatic discovery of all type of clocks (1588 base, Synch. Eth and SDH)
Unified topology view of clocking
refreshes the tracking relationships
All Synchronization Status
for All Clocks.
Monitors clock status
Displays clock alarms
Relationships Tracking
Protection Status Tracking
REAL TIME
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Any Media - Phase delivery through whole infractructure
MA5616/5612,
ATN 9xx, RTN 9xx, 3xx
OSN 500/1500,
OSN1800
MA5600T,
NE40E-X series
OSN 3500/7500,
OSN 6800/8800
Fiber
Copper Radio
LTE/WiMax
GSM/GPRS
UMTS HSPA
UMTS R99/R4
Packet Metro
xDSL(onlyfrequency)
Ethernet
Microwave
GPON
Metro Ethernet
1588V2 ? SyncE NTR MW Sync CES ACR
OTN/WDM
PRTC
Portable tool for testing
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Agenda
Basic concept of syntonisation
Incoming and Present Requirements
Huawei Solutions highlights
Summary
4
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Sync Agility, ALL Scenarios with High Precision
Industry One and Only E2E Sync Solution Provider
Leading IEEE 1588V2 Provider
Rich Application Experiences
One and only E2E Sync Solution Provider in this industry,
covering BS, BITS and Backhaul network.
1588 over any media including xDSL and GPON
E2E 1588v2 solution provider including BITS and BS.
Pilot in standardization, R&D as well as real deployment
1588 hop-by-hop: CMCC
1588 end-to-end: Telenor, Smartone HK
SyncE: CMCC, VDF, TMO
All Sync Solution over Any Media 1588v2, SyncE, NTR, MW Sync., CES ACR
Clock distribution over any media: Microwave, SDH, WDM,
Ethernet, xDSL and GPON
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Summary of Synchronization Technologies Tech.
Frequency
Capable
Time
Capable Application Scenario Key point
SDH/
SyncE √ ×
Synchronization
Network clock
1, Hop-by-Hop deploy
2, High synchronization quality and reliability
3, Easy to maintain
1588V2 √ √ Synchronization
Network clock
1, Hop-by-Hop deploy
2, High synchronization quality and reliability
3, Easy to maintain
1588v2E2E √ ×
Timing carry over the
third or asynchronous
network
1, quick and easy End-to-End deploy
2, Performance depends on the PDV of Network
3, Difficult to maintain
PDH/CES √ × CBR service clock
1, End-to-End deploy
2, Performance depends on the PDV of transport Network
3, Difficult to maintain
NTR √ × Only for DSL G.SHDSL
interface
1, Hop-by-Hop deploy
2, Just used in DSL system
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Summary of Synchronization Technologies Tech.
Frequency
Capable
Time
Capable Application Scenario Key point
SDH/
SyncE √ ×
Synchronization
Network clock
1, Hop-by-Hop deploy
2, High synchronization quality and reliability
3, Easy to maintain
1588V2 √ √ Synchronization
Network clock
1, Hop-by-Hop deploy
2, High synchronization quality and reliability
3, Easy to maintain
1588v2E2E √ ×
Timing carry over the
third or asynchronous
network
1, quick and easy End-to-End deploy
2, Performance depends on the PDV of Network
3, Difficult to maintain
PDH/CES √ × CBR service clock
1, End-to-End deploy
2, Performance depends on the PDV of transport Network
3, Difficult to maintain
NTR √ × Only for DSL G.SHDSL
interface
1, Hop-by-Hop deploy
2, Just used in DSL system
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PtP algorythm – two way
The master and slave exchanges IEEE 1588V2 messages in the following
procedure:
•The master sends a Sync message at t1 and carries the t1 timestamp in the
Sync message.
•The slave receives the Sync message at t2, locally generates the t2
timestamp, and extracts the t1 timestamp from the Sync message.
•The slave sends a Delay_Req message at t3 and locally generates the t3
timestamp.
•The master receives the Delay_Req message at t4, locally generates the t4
timestamp, and sends the Delay_Req message with the t4 timestamp back to
the slave.
•The slave extracts the t4 timestamp from the Delay_Resp message after
receiving it.
According to the preceding information, the following formulas are
satisfied:
t2 - t1 = Delayms + Offset (formula 1)
t4 - t3 = Delaysm - Offset (formula 2)
(t2 - t1) - (t4 - t3) = (Delayms + Offset) - (Delaysm - Offset) (formula 3)
Offset = [(t2 - t1) - (t4 - t3) - (Delayms - Delaysm)]/2 (formula 4)
Obviously, when Delayms = Delaysm, that is, when the transmit and receive
links between the master and slave are symmetric, the following formula is
satisfied:
Offset = [(t2 - t1) - (t4 - t3)]/2 (formula 5)
The slave can calculate the time offset between itself
and the master based on the t1, t2, t3, and t4
timestamps and then corrects its own time to get
synchronized with the master.
The preceding principle shows that IEEE 1588V2 time
synchronization is based on the link symmetry between
the master and slave. If the transmit and receive links
are asymmetric, synchronization errors will occur and
it will be half of the link delay asymmetry.
PtP algorythm – one way
The IEEE 1588V2 protocol implements frequency
synchronization by exchanging Sync messages between
the master and slave. The master periodically sends
Sync messages to the slave. If the slave frequency is
synchronized to the master frequency, then the
accumulative time errors within the same time periods
are the same, as long as the path delay changes are
neglected. In other words, t21 - t20 = t11 - t10, t22 - t21
= t12 - t11, t23 - t22 = t13 - t12, … t2n - t20 = t1n - t10.
If t2n - t20 is greater than t1n - t10, then the slave
frequency is higher than the master frequency, which
means the slave frequency must be decreased.
Reversely, the slave frequency must be increased.
PtP algorythm – 1 and 2 step
Master Slave
t1
t2
t3
t4
Timestamps
known by
slave
t1,t2
t1,t2,t3
t1,t2,t3,t4
Delay_Req message
Sync message
Delay_Resp message
Master Slave
t1
t2
t3
t4
Timestamps
known by
slave
t1,t2
t1,t2,t3
t1,t2,t3,t4
Delay_Req message
Sync message
Delay_Resp message
Follow_Up message
What do you think :
which algorythm require better hardware processing?
How to Decide the Master-slave Path
BMCA also can prevent the timing-loop
like the SSM protocol;
BMCA Start
GM ID A =
GM ID B？
Get the
Master
Clock
Compare
According to
the order left
Difference of
Steps Removed
of A &B > 1
Smaller
is better
YES NO
Two Announce
are from the
same Master?
Compare Steps
Removed of A and B
Parameters in
Announce
GM identity
GM priority2
GM offset
ScaledLogVariance
GM accuracy
GM class
GrandMaster
priority1
YES NO
Compare
the port
ID
Smaller
is better
BITS-Master
Aggregation
Access
A
B
C D
NodeB
BC
BC
BC
BC
BC
BC
BC
BC
NodeB
BITS-Slave OC
OC
OC OC OC
NodeB
Active path of 1588 time/frequency message
Standby path of 1588 time/frequency message
'Best Master Clock Algorithm' is used to decided
the master-slave path in 1588V2
Using Access Network - NTR
N*E1/ FE
NodeB
GWDSLAM
GE
RNC
GE
CBU
PSNSHDSL
N*E1
BSC
N*E1
STM-1/GE
BTS
DSLAM和Modem通过NTR方式传时钟
N*E1/ FE
NodeB
GWDSLAM
GE
RNC
GE
CBU
PSNSHDSL
N*E1
BSC
N*E1
STM-1/GE
BTS
DSLAM和Modem通过NTR方式传时钟
DSLAM and modem
transfer clock signals
using NTR.
MSAN
G.SHDSL
MSAN and modems use NTR
ITU-T G.991.2
Offcourse there it is still possible to use GPON synchronization
SHDSL NTR transports frequency synchronization
over the physical layer of SHDSL and it is similar
to synchronous Ethernet. The clock is recovered
from the serial bit stream on SHDSL and is used
as a clock for the base station. In this way, the
packet clock is synchronized. The figure below
shows how NTR achieves clock synchronization.
The CO first calculates the frequency deviation
between the network clock and local DSL working
clock and then transfers the frequency deviation
to CPE. Then CPE recovers the original network
clock based on the DSL carrier clock and the
frequency deviation transferred by CO.
Yet another hybrid possible – frequency only
The 1588 ACR Frequency Synchronization Solution
Standardisation discussion ongoing
IEEE 1588 standard for a precision clock synchronization protocol for networked measurement and control systems (version 2, 1588-2008).
April 2008.
ITU-T SG15/Q13, WD28. France Telecom. Issues with the Transparent Clock concept of PTPv2 in a telecom environment. Shenzhen, October
2010.
ITU-T SG15/Q13, WD56. Zarlink Semiconductor Inc. Transparent Clock & IEEE 802.1Q Layer Violation [G.8275.1]. Shenzhen, October 2010.
ITU-T SG15/Q13, C1340. Alcatel-Lucent. Time-of-Day distribution across Transport Provider Networks. Geneva, February 2011.
ITU-T SG15/Q13, C1510. Huawei Technologies Co. Comparison of Boundary Clock Simulation Models. Geneva, February 2011.
ITU-T SG15/Q13, C 896. Huawei Technologies Co, China Mobile Communications Corporation. The use of SyncE and IEEE1588v2 for
Phase/Time Distribution. Geneva, May 2010.
ITU-T SG15/Q13, C1353. Symmetricom. Syntonization of Boundary Clocks. Geneva, February 2011.
ITU-T SG15/Q13, WD36. RAD Data Communications. Analysis of Noise Contributers in End-to-End Transparent Clocks. Edinburgh,
December 2010.
ITU-T SG15/Q13, WD61. Cisco. BC and TC noise sources in the equipment. Edinburgh, December 2010.
ITU-T SG15/Q13, C 176, RAD Data Communications, Semtech. Transparent Clock Syntonization Necessity Analysis for IEEE 1588 Telecom
Profile. Miami, November 2008.
National Instrument. IEEE 1588 Boundary Clock and Transparent Clock Implementation using the DP83640 AN-1838. 2008.
G.M. Garner et al. Improvements to Boundary Clock Based Time Synchronization through Cascaded Switches. 2006 Conference on IEEE
1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems.
D. Mohl et al. Improved synchronization behavior in highly cascaded networks. 2007 International IEEE Symposium on Precision Clock
Synchronization for Measurement, Control and Communication (ISPCS2007). Vienna, Austria, October 1-3, 2007.
ITU-T SG15/Q13, WD14. Huawei Technologies Co. Ltd. Test Results of IEEE1588v2 hop-by-hop time synchronization using Boundary
Clocks. San Jose, March 2010.
ITU-T SG15/Q13, C1514. Huawei Technologies Co. Ltd. Effect of Pdelay or Delay Request/Response Turnaround Time, and Sojourn Time, on
Boundary Clock Performance. Geneva, February 2011.
Recommendations for Synchronous Ethernet
G.8251 (2010) The control of jitter and wander within the optical transport network (OTN)
G.8251 Amd1 &2 (2011) and Amd3 (2012)
G.8251 Corr2 (Dec 2011)
G.8260 (2010) Definitions and terminology for synchronization in packet networks (dec2011) app.1 on metrics
Recommendations for timing over packet networks
G.781 (2009), Synchronization layer functions
G.8261 (2008), Timing and Synchronization aspects in Packet Networks
G.8261 Amd1 (2010) G.8262 (2010), Timing characteristics of synch. Ethernet Equipment slave clock (EEC)
G.8262 Amd1 &2 (2012) G.8264 (2008), Distribution of timing through packet networks
G.8264 Amd1 (2010) G.8264 Amd2 & Corr2 (Dec 2011)
Recommendations for OTN
How much delay in my fiber?
Assymetry Conclusions
v = c/n
t= S/c/n
Optical Fiber
Type
Wavelength Refractive
Index
Distance*
Brand A (G.652) 1310 nm 1.4677 204.260 m/µs
1550 nm 1.4682 204.191 m/µs
Brand A (G.655) 1550 nm 1.468 204.218 m/µs
1625 nm 1.469 204.079 m/µs
Brand B (G.652) 1310 nm 1.467 204.357 m/µs
1550 nm 1.468 204.220 m/µs
Brand B (G.655) 1550 nm 1.470 203.940 m/µs
1625 nm 1.470 203.940 m/µs
* delay = Distance / Speed of Light (299.792m/µs) / Refractive Index
S = 400m
0,9076 us < t < 0,9090 us
index of refraction n of a substance
How much delay in my fiber?
-10
-5
0
5
10
15
20
25
1250 1300 1350 1400 1450 1500 1550 1600 1650
Dis
pe
rsio
n D
(p
s/n
m.k
m)
Wavelength l (nm)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1250 1300 1350 1400 1450 1500 1550 1600 1650
Re
lati
ve
de
lay (
ps
/km
)
Wavelength l (nm)
0
0.1
0.2
0.3
0.4
0.5
0.6
1250 1300 1350 1400 1450 1500 1550 1600 1650
Lo
ss
co
eff
icie
nt
(dB
/km
)
Wavelength l (nm)
G.652.A&B
0
0.1
0.2
0.3
0.4
0.5
0.6
1250 1300 1350 1400 1450 1500 1550 1600 1650 L
os
s c
oe
ffic
ien
t (d
B/k
m)
Wavelength l (nm)
G.652.C&D
44
00 14
lllS
D 44
0
2
0 18
lllS
Adelay
