passive optical networks in particle physics experiments

Passive Optical Networks in Particle Physics Experiments

[email protected]

1

24th November, PH-ESE Seminar

24/11/2009

Work conducted by PH-ESE-BE-OPTO Team Members

• Commercial PON technologies

• PONs in Timing Systems for HEP

• Future PONs and their implications in Timing Systems

224/11/2009

Outline

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Commercial PON technologies

[email protected] 24/11/2009 3

o PON definitiono Motivation for current worko PON Protocolso PON Transceiverso Optical Components

PONs in Access Networks• Access Networks are

the last segment connection from COs (central offices) to customers

• They are also called first-last mile networks

• Examples of access networks are: ISDN xDSL WiMAX and most recently

PONs…

WDM mesh

Backbone Network

Metropolitan Network DSLAM

xDSL

POTS

ISDNEthernet, SONET etc

OLT

PON

WiMAX

CO

CO

Access Network

What is a PON?• PON is a Point-to-MultiPoint (PMP) optical network with no active

elements in the signal’s path from the source to the destination• Data are exchanged between a central node, the Optical Line

Terminal (OLT), and a number of end terminals, the Optical Network Units (ONUs)

• A long feeder fiber delivers the data close to the ONUs before signal is split by means of an optical splitter and secondary fibers

• According to where ONUs are placed we have different PON versions namely FTTH, FFTC, FFTB etc

FTTHFTTC

FTTB

General PON Considerations• In the downstream direction (OLT→ONUs) PON is a broadcast network• ONUs are filtering out data not addressed to them• In the upstream direction (ONUs→OLT) however a number of

customers share the same transmission medium and some channel arbitration mechanism should exist to avoid collisions and to distribute bandwidth fairly among ONUs

• TDM is the preferred multiplexing scheme in first generation PONs as it is very cost effective. Dynamic Bandwidth Allocation Algorithms are employed for fairness. All intelingence is built in the OLTs

• Upstream transmission is of burst mode type

FTTC

FTTB

Motivation• There are currently P2P and

P2MP optical links in LHC• P2P links are used in DAQ

due to high bandwidth demands

• P2MP links are used to transmit timing information

• Current TTC system is unidirectional (optically)

• A slow electrical feedback is used to communicate the status of the subdetectors back to the TCS

• It would be beneficial to replace this electrical link with a higher bit rate, “real” time optical link 724/11/[email protected]

h

System Requirements• System has to be able to deliver

synchronous triggers and commands continuously

• Latency has to be fixed at both transmitting and receiving ends

• Recovered clocks have to be of low jitter• System must provide with the flexibility of

both individually addressing or broadcasting to slave nodes

• Slaves have to be able to respond in short time

24/11/2009 [email protected]

TDMA PON Protocols o Ethernet PON (E-PON)

established by IEEE. Work started in 2001, completed in 2005. IEEE 802.3-2005

o Supports Ethernet frames Giga-bit PON (GPON)

established by ITU. Work started in 2001 completed in 2004. ITU G.984

Supports mixed ATM and Ethernet frames through generic encapsulation method (ITU G.7041)

• >95% of LAN data are of Ethernet type but the battle is still on…

Standard EPON GPON

Framing Ethernet GEM

Max. BW 1 Gb/s 2.48 Gb/s

Splitting ratio

16 64

Avg. BW / user

60 Mb/s 40 Mb/s

Max. Reach 20 km 20 km

GPON and EPON Frames Downstream

PC

Bd

Psync (4 bytes)

Ident (4 bytes)

PLOAMd (13 bytes)

BIP (1 byte)

Plend (4 bytes)

US BW Map (N*8 bytes)

Payload

125

μs,

19440 b

yte

s fo

r 1.2

44

G

b/s

sequence used for the sync of the ONU Rx

Counter indicating larger frames (superframes)

Management – Control commands

Bit interleaved parity

Specifies length of BW map and ATM partition

Start time – Stop time for N < 4096 different AllocIDs

Preamble (7 octets)

SFD (4 octets)

Destination Addr. (6 octets)

Source Addr. (6 octets)

Length/Type

Payload / Pad

FCS (4 octets)46 –

15

00 O

ctets

SLD + LLID

Indicates start of frame

Length or type of Ethernet frames mutually exclusive

Error correction

GEM header ONU 1

Data ONU 1

MSB

LSB

MSB

GPONEPON

GEM header ONU N

Data ONU N

…

OLT

ONU 1

ONU N

Downstream

Bandwidth Allocation Schemes

• BW allocation schemes are not part of protocols

• However, both EPONs and GPONs provide with the necessary information for any allocation algorithm to be implemented

• Two main bw allocation schemes:

A. Fixed/Static Bandwidth Allocation (FBA)

B. Dynamic Bandwidth Allocation (DBA)

OLT

ONU N

ONU 2

ONU 1

…

Upstream

FBA PON

1 2 3

4 5

6 7

1 2 3 4 5 6 7

OLT

ONU N

ONU 2

ONU 1

…

Upstream

DBA PON

1 2 3

6 8

1 2 3 4 5 6

7

7

8

4 5

PON Transceivers• Burst mode laser drivers at Slave

(ONU) • FP lasers and PIN diodes for cost

efficiency• Burst mode RXs at OLTs• APDs for high sensitivity and DFB

lasers• WDM filters for upstream-

downstream multiplexing into one fiber

• Bulk-Optic subassembly packaging method

• Cost: ~900$/OLT cost ONU ~90$/ONU. Gigabit Ethernet TRXs $100 SM 1224/09/2009 24/11/2009

1440 nm Rx

1550 nm Rx

1310 nm Tx

Dielectric mirrors

lens

fiber

1550 nm Rx

1310 nm Tx

Dielectric mirrorslens

fiber

Optical Components: Splitter

• Two types of splitters are found

1) Traditional bi-conic fused silica splitter

2) Photonic Lightwave Circuit (PLC) splitter

• PLC has the advantage of smaller footprint

• Better alignment with in/out coupled fibers

• Uniform splitting ratio• Better scalability• Temperature stability

splice

PON Demonstrator for TTC Applications


o PON system specificationso Protocol in the Upstream/Downstream o Transceiver Design on Virtex 5 FPGA

System Specifications

15

Property (General) PON Demonstrator

Clock rate 40 MHz (ie LHC clock rate 40.08MHz)

Max distance Up to 1000m

Encoding | Target BER

NRZ 8b/10b | <10-12

Splitting ratio 1:64

Frame Format Commands + Trigger

BW Allocation Algorithm

Fixed BW

Property (Down|Up) PON Demonstrator

Bit rate 1.6 Gb/s | 800 Mb/s

Latency Fixed and Deterministic| To be determined

Received clock jitter Able to drive a high-speed SERDES24/11/[email protected]

h

System Power Budget

24/09/2009 16TWEPP 2009 21-25 Sep. Paris – Optoelectronics and Links Session

Master

Slave1 Slave2

Upstream

Downstream

Slave N...

Pow

er

(dB

)

PON Demonstrator

• Our system is designed to support 64 slave nodes

• Only 2 slave nodes are used in the first demonstration due to one FPGA platform and number of evaluation board available

• However, all features of a PON can be demonstrated with this system

• Both master and slaves are implemented on the same Virtex 5 platform

• Both physical layer and medium access algorithm have been implemented

1724/11/2009

Master

Slave1

Slave2

Virtex 5

1km

splitters

[email protected]



o Protocol in the Downstream/Upstream

Master

Slave1 Slave2

Upstream

Downstream

Slave N...

Papakonstantinou et. al.

Downstream Frame• Synchronous transmission of super-frames with a period of

1625ns = 65*25ns at 1.6Gbit/s• Comma, “K”, character for frame alignment and for sync • T character carries trigger info. “F” for trigger protection or

other functions• D1 and D2 carry broadcast or individually addressed

information depending on the first bit of the D1 byte.• “R” field contains the address of the next ONU to transmit• 590.8 Mb/s are available for data downstream

19TWEPP 2009 21-25 Sep. Paris – Optoelectronics and Links Session

Slave1

Slave2

Slave64

Upstream Frame

• Slave N1 receives an R character with its address and switches its laser ON

• IFG between successive emissions allows to master receiver to adapt to different bursts

• Channel arbitration is a logic built-in at the OLT

• Total BW 800Mb/s, 7.7 Mb/s are available per Slave node for pure data

2024/11/[email protected]

Upstream frame (2)

24/11/2009 21

Slave1 Slave2

Slave1 Slave2

• Dynamic range (Pslave1/Pslave2) affects IFG and thus available upstream BW/slave

• It also affects the period between successive transmissions

IFG

5 10 15 200

20406080

100120140

Dynamic Range (dB)

IFG

(n

s)

0 50 100 1500

5000

10000

15000

20000

0

200

400

600

800

2

16

32

64

IFG (ns)

Peri

od

betw

een

tw

o T

x

(µs)

Bu

nch

clo

ck c

ycle

s

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o Master/Slave Transceiver Design on FPGA

Master

Slave1 Slave2

Upstream

Downstream

Slave N...

Master Transmitter

24/11/2009 23

Input Outpu

t

1.6Gb/s

...

2161

Frame Generator / Gear Box

...

2201

8B/10B

F I F O

P I S O

80MHz TXUSRCL

K

Clk refDCM

80MHz 80MHz

clock domain crossing

PMA PLL

800MHz80MHz XCLK

40MHz

Tx-PCS

Tx-PMA

GTX Transmitter

• Latency issues at the Tx arise at clock domain crossing points• It is particularly important to bypass any elastic buffers in the data

path• In GTX Tx this is achieved by advanced mode which forces PMA PLL to

phase align XCLK and RXUSRCLK clocks

[email protected]

Slave Receiver

24

Clk ref

PMA PLL

S I P O

REFCLK

800MHz

Rxin1.6Gb/s

2

20

1

Barrel Shifter

PLL80MHz

RXUSRCCLK

80MHz

Phase corrected 80 MHz clk

Input

24/11/2009

CDR

80 MHz XCLK

Retimed

800 MHz Serial

...

DIV1÷10

80MHz clk

800MHz clk0 1 2 3 19. . . • 80 MHz parallel clk can lock on any of the 20 first

edges of the 800 MHz serial clk• That affects the order with which parallel data

are exiting the SIPO• By fitting “K” characters into the frame and

identifying them in a Barrel shifter we can predict the starting point of the XCLK

1817

[email protected]

Slave Rx Latency, Barrel Shifter

2524/11/2009

0 5 10 15 20 25 30 35 40 45 50

t (ns)

bs = 0

0 5 10 15 20 25 30 35 40 45 50t (ns)

bs = 10

0 5 10 15 20 25 30 35 40 45 50

t (ns)

bs = 5

0 2 4 6 8 10 12 14 16 180

2.5

5

7.5

10

12.5

0

45

90

135

180

225

270

315

360f(x) = NaN x + NaNf(x) = NaN x + NaN

ONU2

Barrel Shifter position

Rela

tive D

ela

y (

ns)

Ph

ase

diff

ere

nce

(d

eg

rees)

[email protected]

OLT Burst Mode Receiver

24/09/2009 26

Clk ref

PMA PLL

S I P O

REFCLK

Rxin

800Mb/s2

20

1

24/11/2009

2

20

1

Oversampling x5

Slave1

Slave2

Δφ

11 1 10 0 0 01 X 11 1 010 10 Samples0

CDR

Future PON

– Tri-band PONs– WDM PONs

Tri-Band PONs

• Tri-band PON transceivers utilize 1440nm band

• They can be used in our context to separate the trigger from the control information

• That can simplify protocols of communication and complexity at the OLT


1440 nm Tx (control)

1550 nm Tx (trigger)

1310 nm Rx

1550 nm Rx1550 nm Rx

1440 nm Rx

1310 nm Tx

1440 nm Tx

1310 nm Tx

Master

Slave1 Slave2

Wavelength Division Multiplexing PON

• In a WDM PON scenario each channel (or channel group) is assigned one wavelength upstream and one downstream for communication with OLT

• Benefits are higher bandwidth per channel, loss is independent from splitting ratio, less complicated scheduling algorithm at OLT, easy expansion, better delivery of services

• Main disadvantage is the need for expensive WDM components such as AWGs, filters, tunable lasers / laser arrays / laser per ONU, broadband receivers etc

• “Colorless” WDM PONs are developed to tackle cost issues

Receiver Array

…

WDM Rx

DEMUX

Coarse WDM

OLT

Band A

Band B

λ1, λ2, … λ16

λ17, λ18, … λ32

1 x 16 AWG …

Receiver

RN ONUs

RSOA

Receiver

REAM

λ1

λ17

λ16

λ32

λ1

λ17

λ32

λ16

Coarse WDM

Coarse WDM

λ

Upstream band

Downstream band

…

WDM Tx

SLED

3 dB λ17, λ18, … λ32

Modulated

CW

Summary

• A passive optical network for timing distribution applications has been successfully demonstrated

• In the downstream direction were trigger is transmitted, deterministic latency has been achieved

• A burst mode receiver was implemented in the upstream

3024/11/[email protected]

Questions?

3124/11/2009Papakonstantinou et. al.

PONs in OSI Architecture• PONs reside in the last two layers in the

OSI architecture namely• Data link layer which is responsible for the

access to the medium and for error correction

• Physical layer which is responsible for transmitting and receiving the information

• In GPON terminology the two layers are called: G-Transmission Convergence (GTC) and Physical Media Dependent (PMD)

• EPON modifies MAC layer to allow for bridging data back to the same port

DBA Algorithms

• Requirements for DBA:a) Fairness: Allocates the

bw between users fairlyb) Low delay: Minimize

latency (<1.5 ms for voice channels)

c) High efficiency: Can increase the efficiency of the bw (throughput) and increase peak rate

• Fair Queuing Scheduling• Interleaved Polling with

Adaptive Cycle Time (IPACT)i. Fixed Serviceii. Limited Serviceiii. Constant Credit Serviceiv. Linear Credit Servicev. Elastic Service• Deficit Round-Robin

Scheduling• DBA using Multiple Queue

Report Set• etc ..

FBA – DBA Comparison• FBA algorithm is easy

to implement• However, unused bw

is wasted• FBA is not frequently

encountered

OLT

ONU N

ONU 2

ONU 1

…

Upstream

FBA PON

1 2 3

4 5

6 7

1 2 3 4 5 6 7

• DBA can result in high bw utilization efficiency

• It can also run efficiently different classes of service

• However, efficiency is traded with higher complexity at the scheduler

OLT

ONU N

ONU 2

ONU 1

…

Upstream

DBA PON

1 2 3

6 8

1 2 3 4 5 6

7

7

8

4 5

IPACT Scheduling•ONUs are addressed sequentially in a round robin fashion• In the Simplest IPACT implementation each ONU is granted all requested bw

Limited Service IPACT

• At light loads all alternative scheduling schemes easily outperform fixed service in terms of delay • As network load increases delay for all scheduling schemes converges to fixed service

ONU 1

OLTTx

Rx

Tx

Rx

Tx

Rx

Tx

Rx

84 84 84484

634

234

84 15500234

84

84

84

400

550

150

400

550

150

ONU 2

ONU 3

0400484

0400

21000550634

234

150150

21000550 150150

250

84

250

1550015500-84

15500-84

234

400+84

550+84

150+84 0+84

>max, grant max = 15500 150+84

GRANT frame with grant length = 84

84

400

REPORT frame reporting queue of 400

300300 byte of Ethernet data including overheads

New ONU Registration EPON

OLT

ONUD

iscovery

Win

dow

Disco

ver

y S

lot

Discovery Gate generation process

GATE { DA = MAC control SA = OLT MAC addr, content = discovery + 1 grant + synctime}

Register generation process

Final registration process

Discovery process

Gate Reception

process

Gate Reception

process

Time Time

Request reception process

REGISTER_REQ { DA = MAC control SA = ONU MAC addr, content = pending grants}

REGISTER{ DA = ONU control SA = OLT MAC addr, content = Assigned port (LLID) + Sync Time + echo of pending grants}

GATE { DA = MAC control SA = OLT MAC addr, content = grant}

REGISTER_ACK { DA = MAC control SA = ONU MAC addr, content = echo of Assigned Port + echo of Sync Time}

MPCPDU sent on unicast logical link

MPCPDU sent on broadcast logical link

Ranging/Synchronization in GPON

• GPON implements an alternative equalization scheme• A variable delay EqD is introduced at the ONU• EqD has the objective to male all ONUs appear equidistant from OLT• Phase of signal is measured from first bit transmitted from OLT to last bit

received by ONU• Every time ONU transmits RTT is compared to expected value and EqD is updated

Ranging request

Ranging Tx

Fiber delay

Basic ONU processing delay

E/O conversion delay

E/O conversion delay

O/E conversion delay

O/E conversion delay

RTT = 2Tpd + Ts + TiO1 + TiO2 + TiS1 + TiS2 + EqD Ts + TiO1 + TiO2 + TiS1 + TiS2 < 50 μs

PON Protection

• Resources that require protection:

1) Feeder fiber2) Distribution Fiber3) OLT Transceiver4) ONU Transceiver5) RN (Splitter / WDM

Demux)• Protection Schemesa) Preplanned Protectionb) Dynamic Restoration

…

Feeder Fiber

Distribution Fibers

TxRx

OLT

RN

TxRx

ONU N

TxRx

ONU 1

…

OLT

ONU NONU 1

OLT

ONU

Path 1 Path 2

Protection Schemes

• ITU-T G.983.1 GPON Protocol specifies four protection architectures for PONs

a) Simple feeder fiber architecture

b) Feeder+OLT transceiver

c) Feeder+Distribution+OLT+ONU Transceivers

d) Hybrid protection

…

OLT

ONU NONU 1

…

OLT

ONU NONU 1…

OLT

ONU NONU 1

…

OLT

ONU NONU 1

EPON vs GPON Physical LayerUNIT Downstream

(GPON)Downstream (EPON)

Upstream (GPON)

Upstream (EPON)

Bit-rate Gb/s 1.244/2.48 1 1.244/2.48 1

Wavelength (SF) nm 1480-1500 1480-1500 1260-1360 1260-1360

Mean Tx Power Min

dBm -4 A/+1 B/ +5 C

-7 -3 A/ -2 B/ +2 C

-4

Mean Tx Power MAX

dBm +1 A/ +6 B/ +9 C

2 +2 A/ +3 B/ +7 C

-1

Splitting Ratio <64 <32 ― ―

Max reach Km 20 20 ― ―

Line coding ⁻ NRZ NRZ NRZ NRZ

Rx Sensitivity dBm -25 A/ -25 B/ -26 C

-27 -24 A/ -28 B/ -29 C

-24

Tx On-Off (1 Gbps)

ns ― ― 13 512

Clock recovery /AGC (1 Gbps)

ns ― ― 36 <400

OLT

ONU 1

ONU N

OLT

ONU 1

ONU N

Downstream Upstream

Burst Mode Rx Decision Threshold set

24/09/2009 42TWEPP 2009 21-25 Sep. Paris – Optoelectronics and Links Session

APD

TIA Data Out

+-

LA

R

CRese

t

Peak Detection Circuit

VrefVref

Vref

P2MP Timing Parameters

24/09/2009 TWEPP 2009 21-25 Sep. Paris – Optoelectronics and Links Session

43

PON Protocol

• Synchronous delivery of a periodic trigger with clock rate 25ns, (T) field

• F field to protect the trigger field, (F) field

• Broadcast commands to ONUs, (D1) and (D2) fields

• Individually addressing of ONUs, (D1) and (D2) fields

• Arbitration of upstream channel to avoid collisions due to simultaneous transmissions from multiple ONUs, (R) field

24/09/2009 44

Master

Slave1 Slave2

A1 A2

A1

A2

D2

D1

F

T

Downstream

Upstream

TWEPP 2009 21-25 Sep. Paris – Optoelectronics and Links Session

K

R

F

T

ANDx64

Protocol Properties

• No destination addresses are required to be transmitted

• Easy resynchronization in case of loss of sync

• Simple algorithm for accessing the upstream channel

• Downstream available BW: 9.23 Mb/s/ONU

• Upstream available BW: 7.66 Mb/s/ONU

24/09/2009 4524/11/2009

Upstream Frame• Slave N1 receives an R character

with its address and switches its laser ON

• IFG between successive emissions allows receiver to adopt between bursts

• Upstream contains 32 bytes of <5555> for CDR followed by two SFD, <D555>, bytes for frame alignment

• A 2 byte address field and data are following

• Channel arbitration is a logic built-in at the OLT

• Total BW 800Mb/s, 7.7 Mb/s are available per Slave node for pure data

24/09/2009 46

Data Data . . . 5555


AddrK

32 B2 B

2 B90 B

Master Transmitter

24/09/2009 47

Clk ref

Frame Generator

Gear Box

8B/10BPMA PLL

P I S O

REFCLK40MHz

800MHz

...

1

32

...

216

180MHz XCLK

80MHz80MHz

TXUSRCLK

First clock domain crossing

Txout

1.6Gb/s

Input

Output... 220

1

... 220 1

Frame Clock 40MHzPCS Parallel Clock 80MHz

PMA Parallel Clock 80MHz

Serial Clock 800MHz

Second clock domain crossingThird clock domain crossing

2


TFRK

T

F

R

K

DCM /2 /1

F I F O

OLT Tx – Gear Box

24/09/2009 24/11/2009 48

DCM /2 /1

Frame Generator

Gear Box

40MHz

...

1

32... 2

16

1

80MHz

TXUSRCLK Input

2

TFRK

TF

RK

REF 80MHz

80MHz

40MHz

XXXX

1

1 (o) 2 (e) 3 (o)

2 3

TFRK

RKXX

TF

Frame Generator

...

1

322Gear

Box

80MHz

... 2

16

1XX

XX

40MHz

RK

RK

TF

TF

RK

BW Downstream

• To calculate the BW assigned to each ONU we need:

A) To exclude the trigger, “F” field and “K” and “R” characters 590.76 Mb/s is available for data to all ONUs

B) To exclude BW assigned to 8b/10b encoding

• The usable minimum downstream BW is 9.23Mb/s/ONU (for 64ONUs @ 1.6Gb/s)

24/09/2009 4924/11/2009

OLT Tx Characteristics

24/09/2009 24/11/2009 50

Slave Receiver

24/09/2009 51

Clk ref

PMA PLL

S I P

O

REFCLK

800MHz

Rxin 1.6Gb/s

220

1

Barrel Shifter

PLL80MHz RXRECCLK

80MHz

Phase corrected 80 MHz clk

Input2

16

1

F I F O

Chipscope

ILA

RXUSRCLK

24/11/2009

CDR

80 MHz XCLK

Retimed

800 MHz Serial

... 10b/8b dec.

DIV1÷10

80MHz clk

800MHz clk

0 1 2 3 19. . .

Barrel Shifter


52

Clk refPMA PLL

S I P

O

REFCLK

800MHz

Rxin 1.6Gb/s 2

20

1

Barrel Shifter

RXRECCLK

CDR

1/20

80MHz

80MHzD I

V

80MHz clk

800MHz clk

b0 b1 b2 b3 b4 b5 …

Barrel shifter

b16

b5

b4

b3

b2

b1

b0

b19

b18

b17

. . .

“K”

b17b18

b16 . . .

Barrel Shifter


53

Clkb0

b7b6b5b4b3b2b1

b0b7b6b5b4b3b2

b1

b0

b7b6b5b4b3b2b1

s0s1s2

MU

X

s0s1s2

MU

X

s0s1s2

MU

X

. . .

D

COUT0

D

COUT1

D

COUT7

. . .

S2 S1 S0 O7 O6 O5 O4 O3 O2 O1 O0

0 0 0 b7 b6 b5 b4 b3 b2 b1 b0

0 0 1 b6 b5 b4 b3 b2 b1 b0 b7

0 1 0 b5 b4 b3 b2 b1 b0 b7 b6

0 1 1 b4 b3 b2 b1 b0 b7 b6 b5

1 0 0 b3 b2 b1 b0 b7 b6 b5 b4

1 0 1 b2 b1 b0 b7 b6 b5 b4 b3

1 1 0 b1 b0 b7 b6 b5 b4 b3 b2

1 1 1 b0 b7 b6 b5 b4 b3 b2 b1

Q

Q

Q

BW Upstream

• In our first implementation we give one timeslot of 1625ns to each ONU

• The overhead due to IFG, <5555>, <D555> and address field is 400ns

• That gives a BW utilization (taking into account the 8b/10) of 61.3%

• It corresponds to 7.66Mb/s/ONU (for 64 ONUs @ 800Mb/s)

24/09/2009 5424/11/2009

ONU Rx Characteristics


55

Transceivers for PONs• GPON has far more stringent

requirements than EPON• For this reason GPON

components are in general more expensive than EPON

• OLT needs a 1490 nm laser (usually DFB-DBR)

• Burst Mode Receiver• ONU needs 1310 nm F-P

laser with burst mode laser drivers

• PIN diode or APD at 1490 nm

AGC+

CDR

Coarse WDM

OLT

LDDFB

TOSA

Post-amp

BM ROSA (APD)

… CDR

Coarse WDM

ONU

BM-LD

F-P TOSA

Post-amp

ROSA (PIN)

Optical signalElectrical signal

1310 nm

1490 nm

Tx Enable 16 bits (12.9ns)

Tx Disable 16 bits (12.9 ns)

Total (Tg+Tp+Td) 96 bits (77.2 ns)

Guard time Tg 32 bits

Preamble Time Tp 44 bits (35.2 ns)

Delimiter Time Td 20 bits

Rx Dynamic Range 21 dB

Tx Enable 512 ns

Tx Disable 512 ns

Total (AGC+CDR)

412 ns

Rx Dynamic Range

>21 dB

GPON (1.24 Gb/s) EPON

OLT Rx Characteristics


57

ONU Tx Characteristics


58

Shared PMA PLL


Latency Map

24/09/2009 60

OLT TRx

Tx+

Tx-

Rx+

Rx-

ONU TRx

Tx+

Tx-

Rx+

Rx-

bias

GTX Receiver GTX Transmitter

5 ns/m

17.6 ns 3.2 ns

Constant

75 ns

Module Introduced Latency (ns)GTX Tx 75OLT Board 3.2Fiber 5 ns/mONU Board 17.6GTX Rx Constant

FPGA

FPGA

OLTONU

OLT Tx Latency

24/09/2009 61

Frame Generator

Gear Box

8B/10BPMA PLL

P I S O

Input

Output

12.5 ns

12.5 ns

12.5 ns25 ns

Module Introduced Latency (ns)Gear Box 12.5FPGA Tx Interface 12.58b/10b encoder 12.5FIFO buffer bypass 12.5PMA+Interface 25TOTAL 75

Clk ref

DCM /2 /1

24/11/2009

FPGATx Int.

12.5 nsF I F O

ONU Rx Total Latency

24/09/2009 62

Module Introduced Latency (ns)PMA + Interface 50buffer bypass 25Barrel Shifter 12.58b/10b decoder 12.5FPGA Rx Interface 25TOTAL 125.5

50 ns 12.5 ns25 ns 25 ns12.5 ns (not yet)

Clk ref

PMA PLL

S I P

O

Rxin

220

1

Barrel Shifter

PLL

Input2

16

1

F I F O

FPGA Rx Interface

CDR

... 10b/8b dec.

DIV1÷20

Jitter Map

63

Master

Tx+

Tx-

Rx+

Rx-

Slave

Tx+

Tx-

Rx+

Rx-

bias

GTX Receiver GTX Transmitter

Ref CLK

pk-pk: 2.21 ps

RMS: 2.05 ps

pk-pk: 53.63 ps

RMS: 11.43 pspk-pk: 58.66

psRMS: 15.11

ps

pk-pk: 31.42 ps

RMS: 13.32 ps

Recovered CLK

1 Km24/11/[email protected]

h

pk-pk: 66.62 ps

RMS: 1.75 ps

SCM and OCDMA over PONs

Hybrid WDM-SCM (sub-carrier modulation) PON

Migration scenario with OCDMA (Optical Code Division Multiplexing Access)

Colorless ONUs based on RSOAs

Self-Seeded (Reflective Semiconductor Optical Amplifier) RSOA based ONUs at 1.25 Gb/s

Externally-Seeded RSOA (Reflective Semiconductor Optical Amplifier) based ONUs at 1.25 Gb/s

Rx1… A

WG

Coarse WDM

OLT

λD1, … λDN

λU1, … λUN

1 x N router …

RN

RxN

RSOA

λDN

λUN

λDN

λUN

Coarse WDM

RxN

Tx1

… AWG

TxN

SLED

3 dB

λU1, … λUN CW

λD1, … λDN Modulated

λD1, … λDN

λUN CW ONU N

Optically Injection Locked ONUs

Externally-Seeded Injection Locked FP-LDs. 1.5 Gb/s over 30KmRx

Coarse WDM

OLT

AWG 2

…

RN

Rx

FP-LD

λDN

λUN

Coarse WDM

Rx

FP-LD

…

AWG1FP-

LD

3 dBONU N

C-Band EDFA

L-Band EDFA

CW Upstream or Downstream

Modulated Upstream or Downstream

DFB seeded Injection Locked VCSELs, 1550 nm 2.5 Gb/s over 25 Km

passive optical networks in particle physics experiments

Documents

pon definitionmotivation

pon gpon

different pon versions

p2mp optical links

optical splitter

passive optical networks

ethernet type

multipoint pmp optical