Recent Results on Op?cal Access Networks from the PRIN Project ROAD- NGN

Transcription

1 Rete O&ca di Accesso a Divisione di frequenza e/o di lunghezza d onda per soluzioni Next Genera?on Network Recent Results on Op?cal Access Networks from the PRIN Project ROAD- NGN Presenter: Roberto Gaudino Politecnico di Torino, Op0cal Communica0on group (OPTCOM Corso Duca degli Abruzzi 24, Torino, Italy, E- mail: [email protected] Riunione Gruppo Re?, Cavalese, 2015 January 14 th

2 ROAD- NGN Project dura0on: February January 2016 Gabriella Cinco&, Coordinator Julian Hoxha Luca Caldaroni Pierpaolo Boffi Mario Mar?nelli, Achille PaWavina Guido Maier Lucia Marazzi, Paola Parolari Roberto Gaudino Valter Ferrero Roberto Cigliu& Ernesto Ciaramella Fabio BoWoni Marco Presi Luca Valcarenghi Piero Castoldi Marco Santagius?na Antonio Mecozzi Cris?an Antonelli Francesco Matera (FUB) Francesco Vatalaro Marco Petracca Romeo Giuliano Paolo Mancuso Francesco Matera 2

3 ROAD- NGN project in a glance Scenario: Passive Op0cal Networks (PON) for FTTH solu0ons Project focus: improvements compared to current PON standards in terms of: 1. unbundling op0ons See my presenta0on last year for the 2014 Cor0na Mee0ng 2. Increase in bit rate per wavelength 3. Cost effec0ve solu0ons to handle mul0ple wavelengths 3

4 Outline of the presenta?on Introducing the scenario: Passive Op0cal Network (PON) access architectures The most recent ITU- T standard for PON: NG- PON2 The ROAD- NGN research goals: beyond NG- PON2 Proposed architectures for upstream and downstream transmission Experimental results 4

5 Outline of the presenta?on Introducing the scenario: Passive Op0cal Network (PON) access architectures The most recent ITU- T standard for PON: NG- PON2 The ROAD- NGN research goals: beyond NG- PON2 Proposed architectures for upstream and downstream transmission Experimental results 5

6 Passive Op?cal Network (PON) architecture Central Office Passive Optical Splitters O/E O/E OLT (Optical Line Terminal) ODN (Optical Distribution Network) O/E ONU (Optical Network Unit) Today mostly deployed standard: GPON (ITU- T G.984): Number of user per PON tree: up to 64 Mul0plexing technique: TDM in downstream at 2.5 Gbps, TDMA in upstream at 1.25 Gbps 6

7 ITU-T most recent standard: NG-PON2 (TWDM-PON) Defined by FSAN and ITU-T in the Recommendation G Gigabit-capable passive optical networks (NG-PON2) TWDM-PON: time and wavelength division multiplexed PON Backward compa,ble with previous PON standards (GPON, XGPON and RF- Video) NG- PON2: 4 new wavelengths (per direc,on) h"p:// REC- G I/en 7

8 NG-PON2 features 4 wavelengths per direction, 100 GHz spacing Upgradeable to 8 wavelengths (50 GHz) TDMA on each of the 4 wavelengths Each wavelength is treated as an independent XG-PON Downstream: 10 Gbps Upstream: 2.5 Gbps Traditional Splitter-based PON Backward compatibility with ODN loss classes Nominal 1 (N1 class) Nominal 2 (N2 class) Extended 1 (E1 class) Extended 2 (E2 class) Minimum loss 14 db 16 db 18 db 20 db Maximum loss 29 db 31 db 33 db 35 db 8

9 Outline of the presenta?on Introducing the scenario: Passive Op0cal Network (PON) access architectures The most recent ITU- T standard for PON: NG- PON2 The ROAD- NGN research goals: beyond NG- PON2 Proposed architectures for upstream and downstream transmission Experimental results 9

10 ROAD- NGN targets besides physical layer unbundling presented last year in Cor0na Target #1: Increase the bit rate per wavelength in both direc0ons Toward Gbps in both direc0ons (as symmetrically as possible) Target #2: Simplify wavelength handling for the upstream, trying to solve one of the most cri0cal issues to be solved in TWDM- PON 10

11 Outline of the presenta?on Introducing the scenario: Passive Op0cal Network (PON) access architectures The most recent ITU- T standard for PON: NG- PON2 The ROAD- NGN research goals: beyond NG- PON2 Proposed architectures for upstream and downstream transmission Experimental results 11

12 The recipes to achieve these targets Target #1: higher bit rate per wavelength Introduce more sophis0cated modula0on formats and mul0plexing techniques Frequency division mul0plexing (FDMA) In both direc0ons (UA and DS) Implemented at the electrical level on top of each wavelength M- QAM on each electrical subcarrier in the FDMA comb As a result: digital signal processing (DSP) required at both the ONU and OLT Constraint: low DSP rate at the ONU to keep cost and power consump0on at reasonable levels 12

13 FDM in downstream We propose to use 32 electrical subcarrier, each carrying 16- QAM a 1 Gbps net data rate These FDM spectrum totally fill the available downstream electrical bandwidth over a typical direct- detec0on op0cal link (7-8 GHz 3dB bandwidth) Downstream FDM signal spectrum at ONU receiver Each spectral slice is dedicate to a given ONU (i.e. FTTH user) 13

14 Experimental setup OLT transmiwer DSP emula,on through a Tektronix 20 Gsample/s arbitrary waveform generator Passive fiber plant ODN emulated on a real metropolitan fiber testbed Realis,c ODN losses as requested by ITU- T ONU receiver Complete optoelectronic receiver Offline DSP emula,on in Matlab aver ADC using a 50 Gsample/s real,me oscilloscope 14

15 Experimental results Aher a careful op0miza0on of many system parameters we obtained 32 Gbps downstream at FEC threshold for the required ODN losses FEC threshold BER= (as required by G I.4). Launched op,cal power at OLT BER contour plot 15

16 DSP Complexity at OLT The DSP required at the central office is for sure significantly more complex than the current NG- PON2 (TWDM- PON) Mostly because it must run at about 20 Gsample/s (and thus also requires extremely fast DAC) But the achieved capacity per wavelength is 3 0mes bigger than NG- PON2 Moreover, in most op0cal transmission sectors it is today widely recognized that DSP is required to beat the 10 Gbps per wavelength barrier 16

17 ONU complexity (from EU STREP FABULOUS ) n At the ONU RX and after photo detection, electrical RF down-conversion is applied so that DSP can be at baseband and only on the spectral slice dedicated to each specific ONU f n n RF j Baseband digital signal processing on I/Q components DS data out The required baseband processing for our proposal can be done using DAC and ADC working in the 500 Msample/s range Low-cost chipsets are already available today to implement this electronic architecture l UWB chipsets (for instance from FDMA Access By Using Low-cost Optical Network Units inalereon) Silicon photonics FP7-ICT Challenge 3.5 STREP project n FABULOUS 17

18 Target #2: wavelength handling Target #2: simplify wavelength handling for upstream In the ITU- T NG- PON2 standards each ONU should generate its upstream wavelength with very high accuracy (100 GHz grid) by a tunable laser This is the key technological obstacle to be solved today No tunable lasers exist today with a price compa0ble with ONU We propose a reflec0ve approach for the upstream that completely solve this issue 18

19 Proposed reflec?ve solu?on for US Generate also the upstream wavelength at the central office by a comb of CW lasers Modulate them back in reflec0on at the ONU 19

20 Reflective PON with OLT centralized wavelength generation Key idea: upstream wavelengths are generated at the OLT, and modulated in reflection TX DS array TX US array Bank of CW laser, Not modulated RX array AWG AWG OLT ODN ONU i TOF Upstream signal TOF Reflec0ve TX We studied in the ROAD-NGN project several variants of this architeture Key point: the ONU does not need tunable lasers RX TOF: Tunable Op,cal Filter 20

21 Reflective Semiconductor Optical Amplifiers The Politecnico di Milano group inside ROAD-NGN experimentally implemented this goal using reflective semiconductor optical amplifiers R-SOA: Combination of a SOA and an optical mirror Input fiber I(t) SOA Op0cal Mirror SOA gain changes with driving current SOA are semiconductor optical amplifier with the following characteristics Low cost (at least potentially, if they have mass production) Medium gain (10-20 db peak gain) Medium-high noise figure (7-8 db) Some residual polarization dependence The gain can be modulated by changing the injected optical current Modulation speed is 1-2 GHz maximum 21 21

22 POLIMI Experimental results POLIMI, using high- performance RSOA developed in the EU- Project FDMA in the upstream Top performance: Up to 16 users per wavelength, each at 1 Gbps for a total upstream capacity of 16 Gbps per wavelength Flexible solu0on to achieve higher number of users per wavelength 22

23 POLITO Experimental results POLITO, using Silicon- Photonics high speed R- MZM developed in the EU- Project FABULOUS FDMA in the upstream Top performance: Up to 32 users per wavelength, each at 1 Gbps for a total upstream capacity of 32 Gbps per wavelength 23

24 Just a liwle of self- adver?sement If you work in op0cal networks, please consider the FOTONICA 2015 Italian Na0onal Conference SAVE THE DATES: 24

25 Conclusions In ROAD- NGN we have demonstrated solu0ons that can be of interest for the next genera0on of ITU- T PON standards NG- PON3?? Will all this capacity be required in fixed access? A candidate applica0on: using NG- PON3 to support front- hauling in Cloud Radio Access Networks (C- RAN) for 5G mobile networks CPRI higher data rate per remote radio unit: 10 Gbps 25

26 Rete O&ca di Accesso a Divisione di frequenza e/o di lunghezza d onda per soluzioni Next Genera?on Network Thank you for your awen?on! Recent Results on Op?cal Access Networks from the PRIN Project ROAD- NGN Presenter: Roberto Gaudino Politecnico di Torino, Op0cal Communica0on group (OPTCOM Corso Duca degli Abruzzi 24, Torino, Italy, E- mail: [email protected]

27 Rete O&ca di Accesso a Divisione di frequenza e/o di lunghezza d onda per soluzioni Next Genera?on Network BACK- UP slides Recent Results on Op?cal Access Networks from the PRIN Project ROAD- NGN Presenter: Roberto Gaudino Politecnico di Torino, Op0cal Communica0on group (OPTCOM Corso Duca degli Abruzzi 24, Torino, Italy, E- mail: [email protected]

28 Front-haul and CRAN explained

29 (one of today) mobile backhaul architecture RF TX Antenna RF RX Antenna site hardware (base station) Physical Layer Digital Signal Processing (LTE, LTE-Advanced, 5G) Network layer interface Gigabit Ethernet optical cards Optical fiber link Central office 29

30 Zooming on the physical layer Antenna I/Q modulator I Q RF local oscillators I I/Q demod Q DAC DAC ADC ADC Very high speed rate at this interface Physical Layer DSP Network layer interface This layer is very computationally intensive in recent mobile standards, and it will become more and more sophisticated in the near future 30

31 Example Wireless RF bandwidth: 20 MHz Sampling frequency: >20 Msamples/s Bit per sample: 16 bit/sample Resulting rate for one component: 320 Mbit/s x2 I/Q streams: 640 Mbit/s x3 antennas for each radio site xn due to MIMO xm due to multi-carrier DAC and ADC required bit rate Future trends: 31

32 The new vision: front-hauling approach Antenna I/Q modulator I Q DAC DAC RF local oscillators Bit rates in the Gbps range at this interface I/Q demod Very thin framing protocol (such as CPRI) I Q ADC ADC CPRI transceiver Physical Layer DSP Network layer interface Optical fiber link (P2P or PON) Central office 32

33 Common Public Radio Interface (CPRI) CPRI current data rates CRAN Cloud Radio Access Networks Advantages: All functions are centralized and virtualized Much easier software reconfiguration Physical layer coordination of many antenna sites 33

34 Concept of CoMP in LTE Advanced Coordinated Multipoint (CoMP): Joint processing possible if all antennas are centrally controlled It allows: coordinated scheduling Beamforming Crosstalk cancellation Distributed MIMO among antennas Central office Coordinated transmission control 34