Access Networks and the

Prof. Rami Langar LIGM/UPEM [email protected] http://perso.u-pem.fr/~langar

1 Access Networks Evolution o A large number of recent technologies:

n xDSL and unbundling of the local loop n CATV, HFC (Hybrid Fiber Coax) n FTTx, PON n Power Line Communication (PLC) n WLL ( Local Loop) o 802.11 (WiFi) o 802.16 (Wimax) o Satellites (LEO/MEO/GEO) o 3rd Generation Mobile Systems (UMTS) o LTE, femtocells n …

2 The Local Loop solutions

100 ADSL 90 Mobile 3G 80 Cable 70 WiMAX

60

50 Satellite

Rural b Urban Suburban

40 urban Dense Sparsely populated Sparsely

30 100k Relative complexity/cost (%) complexity/cost Relative

20 Mobile 4G 10k

10 1k

0 0.1 1 10 100 1,000 10,000 100,000 3 Population density (per km2) Length of the wired Local Loop

France

4 Communication medium (wire)

5 xDSL access

6 Legacy wired DSL access infrastructure

STB

DSLAM modem ADSLF 1 F STB F Modem ADSL 34 F Network servers STB - DSLAM modem ADSLF F 1 STB F Modem ADSL 34 F

STB

DSLAM modem ADSLF 1 F STB F Modem ADSL 34 F

STB

DSLAM modem ADSLF 1 F STB F Modem ADSL 34 F

7 The xDSL Loop

PABX (Tel) IP network

LAN xDSL Modem BAS PABX X X X X Data xDSL Network ATM/SDH Modem Network DSLAM GW PSTN

8 Legacy wired DSL access infrastructure (2)

PABX ADSL

DSLAM

ATM/SDH WDM

PABX ADSL ATM/SDH ATM/SDH

ATM/SDH DSLAM WDM

Typical infrastructure of incumbent telecom operators WDM: Wavelength Division SDH: Synchronous Digital Hierarchy; ATM: Asynchronous Transfer Mode DSL: à ATM/SDH aggregation being replaced by Giga access 9 xDSL access evolution: ATM vs Ethernet

10 The ADSL modulation Discrete multitone modulation (DMT) (DSP-based) 20 canaux (~4 kHz/canal) 256 canaux (~4 kHz/canal) ~8 bits par intervalle d’horloge ~8 bits par intervalle d’horloge

⇒ ~ 20 x 4.000 x 8 = 640 kbit/s ⇒ ~ 256 x 4.000 x 8 = 8,2 Mbit/s

4 kHz

Up Down +- 3,5 dB/Hz

A DMT modem permanently evaluates the line quality, so as to adaptively recompute the power and the optimal capacity in bit/s per Hz to allocate to each channel 11 ADSL: -distance constraints

Maximum capacity (in Mbit/s) ADSL PABX 100

10 ADSL

Data 1 Network 0 1 2 3 4 5 6 7 Distance (in kilometers)

PABX ADSL

Data Network

12 ADSL evolutions

o ADSL 2 n New coding and modulation techniques, leading to: o More bandwidth (maximum rate of 10Mbps downstream, apprx 1Mbps upstream) at a given distance o Or longer reachable distances (for a given rate) n Inverse Mux, possibility to use lower frequencies

o ADSL 2+ n Higher frequency range for download n leading to a maximum of 25 Mbps for download (for VERY short distances) n Same frequency range for upload. Still 1Mbps.

13 The DSL wiring and unbundling

ULL: Unbundling Local Loop (at the concentrator level or DSLAM level) 14 xDSL bandwidth-distance product

– ADSL (Asymmetric Digital Subscriber Line) – SDSL (Symmetric DSL) – HDSL (High-bit-rate DSL) – VDSL (Very-high-bit-rate DSL)

15 xDSL spectral utilization

25 kHz 1,1Mhz POTS (plain old tel. service) 2,2Mhz

upstream downstream ADSL ADSL2 ADSL2+

VDSL

12Mhz

10Khz 100Khz 1Mhz 10Mhz 16 FTTx

17 The Optical Loop o FITL (Fiber In The Loop) or FTTX () n X=C, Cabinet, Curb n X=N, Building n X=H, Home n X=T, Terminal o FTTX development examples n FTTH by Free (FR); FTTB by Numericable (FR), Fastweb (IT) n Future: FTTC + femtocell/WiMax Aps o FTTX usually based nowadays on Ethernet MAN with n Direct fiber connections n Use of Ethernet PONs (EPONs) (previously APON for ATM over PON) n Use of remote DSLAMs (e.g.VDSL)

18 PON ()

Unpowered optical splitters enable a single fiber to be used by multiple users.

• Downstream: broadcast to all • Upstream: TDMA (CSMA/CD not adapted to the speed of EPON)

• 3 types of PON: • ATM over PON (APON) • Ethernet PON (EPON) • Gigabit PON (GPON)

OLT: Optical Line Terminaison ONU/ONT : Optical Network Unit/Terminal 19 CATV cabling

20 The Cable Loop (CATV) o Reusing existing CATV equipment n Inexisting in some countries n Widely deployed in some others (north america) n Upload channel problem (usually TDMA as in PONs)

o DOCSIS standard uses slots nnumbred from 1 to 4096

o Up to 14 slots can be used per communication

o Slot reservation by sending a request on a random slot (Binary Exponential Backoff algorithm) n Large bandwidth (more than 800 MHz)

o Frequency multiplexing to handle different applications

21 THE WIRELESS LOOP

22 The Wire-Less Loop (WLL)

Data Network

No real applications in early 2000s Nowadays new products and protocols (4G, Wimax, LTE) à bypass DSL The Wire-Less Loop (2) o : n Up to 2Mbps (3G) n Up to 100 Mbps (4G) n Up to 1 Gbps () o IEEE 802.11 (WiFi) n 11Mbps (11.b), 54Mbps(11.a et 11.g) , 100Mbps under investigation n Limited coverage o WiMax (IEEE 802.16) n 802.16a (deployed early 2005): o point to point connection up to 134Mbps. o Point-to-multipoint: up to 75Mbps for cells of several kms o Target: Fixed access n 802.16e: o Includes roaming (speed around 100km/h) o Target: mobile broadband access

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Femtocell and OFDMA spectrum sharing

• A femtocell is a small cellular base station typically designed for use in a home or small business. • It can connect to the Mobile Operator Network through Internet

25 The Satellite Loop

LEO (Low Earth Orbit) 500 – 1.500 km

MEO (Medium Earth Orbit) 5.000 – 12.000 km

GEO (Geostationary Earth Orbit) 36.000 km

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