New-Tech Europe Magazine | April 2019

DOCSIS Specification Version

Maximum Downstream Capacity

Maximum Upstream Capacity

Production Date

Features

Initial release that included one downstream and one upstream channel. Primary use was fast internet. Added VoIP capabilities, BPI security between Cable Modem and CMTS, and, standardized the DOCSIS 1.0 QoS mechanisms. Supported voice calls, gaming, and streaming Enhanced upstreamdata rates. Supported symmetrical services that depended on upstream and downstream channels and improved the upstream data traffic. Significantly increased downstream/upstream data rates, introduced support for IPv6, and introduced channel bonding. Supported combining multiple channels for increased throughput. Significantly increased downstream/upstream data rates and restructured channel specifications. Supported OFDM technology in upstream and downstream channels to get more traffic on existing channels.

1.0

1997

40 Mbit/s

10 Mbit/s

1.1

2001

40 Mbit/s

10 Mbit/s

2.0

2002

40 Mbit/s

30 Mbit/s

3.0

2006

1.2 Gbit/s

200 Mbit/s

3.1

2013

10 Gbit/s

1–2 Gbit/s

product complies with the specification standard, and then marks it as such for the public. In the latest DOSCIS 3.1 specification, orthogonal frequency- division multiplexing (OFDM 2 ) is a key feature that increases bandwidth by enabling the bundling of dense 25KHz “sub carriers” channels of up to 192Mhz, as opposed to the Europe 8MHz / United state 6MHz of Single Carrier Quadrature Amplitude Modulation (SCQAM 3 ) channels. The granularity of channel width helps to use sparsely spread spectrum, to achieve higher throughput. Combining a new generation of Forward Error Correction (FEC 4 ) called LDPC 5 with OFDM enables use of the existing cable infrastructure without digging tranches around a home, which allows the technology to be easily deployed. The standard also improves the cost of every bit with the Active Queue Management (AQM 6 ) which enables better management of queues in the system and improves

the response time (known as latency). The DOCSIS specification continues to evolve. Due to other service needs, such as Over The Top (OTT 7 ), video, 4K video, 3DTV, etc., there are discussions about the upcoming Bi- Directional/Full Duplex DOCSIS 3.1 specification that will enable upstream and downstream channels on the same spectrum in parallel, as opposed to the dedicated upstream channels and different dedicated downstream channels in 3.1 Half Duplex. This makes it possible to increase the bandwidth and enable these services. The Current DOCSIS Status Today, DOCSIS 3.1 is used in European or US specifications, which differ in channel spacing etc. and upstream and downstream traffic speed. Physical channels cannot pass unlimited traffic of information. To overcome this limit and to achieve a certain bit rate, this specification combines or “bonds” several channels and links

them together, thereby enabling wide broadband downstream and upstream channels. Most of the traffic is on the downstream channel, such as downloading of media movies files, etc., and less so on the upstream channel which is used for uploading to the cloud or other services. This results in asymmetric traffic. For the downstream channel, there are 32 SCQAM channels and two OFDM channels. For the upstream channel, there are eight SCQAM channels and two OFDMA (Which is OFDM technology for the Upstream) channels. If every SCQAM channel has a physical limitation and supports 27-50 Mbps, the combination of 32 downstream channels with two OFDM and eight upstream channels with two OFDMA provide the following bandwidth: In the U.S. and Israel Downstream: (32 channels * 38Mbps = 1,216Mbps) + (2 channels OFDM * 1880Mbps = 3,760Mbps) Total: ~4,976Mbps

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