Fibre or copper in the access - an unbiased comparison

Dr. Rong Zhao

Detecon International GmbHCologne, Germany

Outline

• Introduction• The Need for Speed: Nielsen’s Law• FTTx Architecture• What is the Maximum Speed?• DSL Technologies• Cable Technologies• Optical fiber technologies• Summary

Introduction

Fiber or Copper in the Access?

The Need for Speed: Nielsen’s Law

• A high-end user's connection speed grows by 50 percent per year, or doubles every 21 months.

Digital Agenda 2020• “To match world leaders like South

Korea and Japan, Europe needs download rates of 30 Mbps for all of its citizens and at least 50% of European households subscribing to internet connections above 100 Mbps by 2020.”

Source: Jakob Nielsen, http://www.useit.com/alertbox/980405.html

“Nielsen’s Law of Internet bandwidth”

FTTx Architecture

Architecture

• FTTC/B/H: fiber close to end users

• FTTdp (Fiber to the Distribution Point) or FTTS (Fiber to the Street): one step between FTTC and FTTB

• The existing copper infrastructure would be reused to minimize the high investment FTTx

FTTx Topology

Topology

• Point to Point (P2P) • Point to Multi-Point (P2MP)

What is the Maximum Speed?

The Shannon Limit

• C is the channel capacity in bits per second (bps)

• B is the bandwidth of the channel in Hertz (Hz)

• S is the average received signal power in Watts (W)

• N is the average noise power in W• S/N is the signal-to-noise ratio expressed

as a linear ratio (not logarithmic scale in decibel, dB)

⎟⎠⎞

⎜⎝⎛ +=

NSBC 1log2

DSL Technologies (Basic)

Pros and Cons

• Based on existing copper infrastructure

• ADSL2+ supports frequencies up to 2.2 MHz, and VDSL2 supports frequencies up to 30 MHz.

• DSL speeds decrease with increasing distance DSLAM

• VDSL2 (e.g. 30a profile) can achieve speeds of up to 100 Mbps

Source: IDATE

DSL Technologies (Bonding)

Pros and Cons

• Bonding combines multiple copper pairs into a single transmission channel

• Increasing the speed: e.g. 80 Mbps at 500m, or

• Extending the reach: e.g. 40 Mbps at 1000m

• At least two pairs are required, but not always available (difficult for a nationwide service offering)

Source: ZTE

DSL Technologies (Vectoring)

Pros and Cons

• Reducing the far-end and near-end crosstalk (FEXT and NEXT)

• Standardized by the ITU Standards Association as G.Vector

• ITU-T G.933.5 supports far-end crosstalk cancellation in the downstream and upstream directions

• Not allow physical (local or sub-loop) unbundling and third parties are limited to bitstream services

Source: Alcatel-Lucent

DSL Technologies (Phantom mode)

Pros and Cons

• Phantom mode signals can be used, in combination with vectoring and bonding, to increase the capacity of a single communications channel using multiple copper pairs

• Alcatel-Lucent (Phantom Mode): 300 Mbps at 400m (or 100 Mbps at 1000m) using two pairs of 0.6-mm twisted-pair cable; bit rates 2.5 times greater than two bonded pairs

• Nokia Siemens Network (SuperFast): 825 Mbps over 400m and 750 Mbps over 500m for its “SuperFast” technology

• Huawei (SuperMIMO): 700 Mbps over 400m using four copper pairs; boosts DSL bandwidth by 75%, from an average of 100 Mbps per twisted pair to about 175 Mbps

• At least two pairs are required, but not always available (difficult for a nationwide service offering)

• Standardization is not finalized

Cable Technologies (DOCSIS 3.0)

Pros and Cons

• Data Over Cable Service Interface Specification (DOCSIS)• Standardized by ITU-T. The current generation, DOCSIS 3.0 (ratified as ITU-T

Recommendation J.222)• Downstream capacity (speed) per channel:

• Europe: ~50 Mbps• North America: ~38 Mbps

• Commercially available DOCSIS 3.0 equipment can provide:• Download capacity of ~400 Mbps (8 channels) on the DOCSIS CPE• Upload capacity of ~120 Mbps (4 channels) on the DOCSIS CPE

• Shared medium and limited upload capacity

Cable Technologies (DOCSIS 3.1)

Pros and Cons

• Next generation of standards for cable networks• Goal:

• >=5 Gbps for the download bit rate• >=1 Gbps for the upload• (This is shared capacity used by all homes on the same coaxial cable

segment.)• Increase the available cable spectrum and aim to use it more efficiently by:

• New, more efficient modulation and error-correction schemes, including orthogonal frequency-division multiplexing (OFDM) and low-density parity-check (LDPC) codes

• Additional downstream RF spectrum by using higher frequencies • Additional upstream RF spectrum by moving the “split” between upstream

and downstream transmissions• Standardization is expected to be complete in the next few years

Cable Technologies (DOCSIS 3.0 vs. 3.1)

Comparison

DOCSIS 3.0 DOCSIS 3.1

Now Phase 1 Phase 2 Phase 3

DS Range (MHz) 54 – 1002 108 – 1002 300* – 1152 500* – 1700

DS QAM Level 256 256 ≥ 1024 ≥ 1024

# DS Channels 8 24 116* 200*

DS Capacity (bps) 300M 1G 5G 10G

US Range (MHz) 5 – 42 5 – 85 5 – 230* 5 – 400*

US QAM Level 64 64 ≥ 256 ≥ 1024

# US Channels 4 12 33* 55*

US Capacity (bps) 100M 300M 1G 2G*

Source: Cisco. DS = downstream; US = upstream; * = to be determined.

Optical Fibre Technologies

Overview

Source: FTTH Handbook, Edition 5.

• Passive Optical Network (PON)• More with P2MP Topology• Shared bitrate• APON, BPON, GPON/EPON,

10GPON, WDM-PON (test)• Download: 2.5~10• <20km for GPON

• Ethernet• More with P2P Topology• Dedicated bitrate• Fast Ethernet/Gigabit Ethernet• 100M~10G per subscriber• >20km

Summary

Technical View

• As bit-rate requirements continue to grow, the ability of broadband technologies to evolve to meet future needs is important. Infrastructure upgrades should be carried out with a long-term view.

• Network operators are providing download bit rates of 50 Mbps or even more using VDSL2+ and DOCSIS 3.0 technologies.

• Using bonding, vectoring and phantom mode, DSL could provide maximum bit rates of several hundred Mbps over short distances, but with limitations compared to all-fibre networks

• VDSL2 can be favourably applied in FTTB scenarios within a short distance (tens of meters); two available copper pairs per apartment could make bonding a viable option.

• Cable networks using DOCSIS 3.0 can provide download speeds comparable to VDSL2, but the upload speed is restricted compared to the download speed, and with shared capacity among many subscribers

• Copper-based technologies will coexist with fibre-based technologies for some time• FTTH and FTTB are future-proof network architectures, and have been identified as the

target solutions for wireline broadband networks

Contact

Dr. Rong Zhao

Detecon International GmbHSternengasse 14 – 1650676 Köln GermanyPhone: +49 221 91612941Mobile: +49 170 2276103Rong.Zhao@detecon.com

Thank you for your attention!

www.ftthcouncil.eu