docsis tutorial Archives

2 09, 2016

How DOCSIS Revolutionized the Cable Industry

Mia Colabrese2016-09-02T08:00:21-04:00September 2nd, 2016|

How DOCSIS Revolutionized the Cable Industry The cable industry is constantly facing competitive threats from companies like Google and Verizon who up the data speed game with fiber optic cable. They compete by offering higher and higher data speeds at lower and lower prices. But before we get into that, let’s look back at the 20 years of DOCSIS history and how DOCSIS has revolutionized the cable industry. Google Fiber Expansion (Source: Google.com) 20 Years Ago - The Internet Emerges The year was 1996. Broadband Library was celebrating

9 09, 2013

What is DOCSIS PNM?

Mia Colabrese2021-08-17T16:17:19-04:00September 9th, 2013|

What is DOCSIS PNM and How Does it Work? Recently I wrote about DOCSIS PNM technology and a company working on is called Nimble This. In this article I want to highlight a mechanism behind how DOCSIS PNM works. DOCSIS Pre-Equalization DOCSIS PNM begins with a relatively well known DOCSIS feature called DOCSIS pre-equalization. I've previously covered adaptive pre-equalization, but here is a refresher. Starting with DOCSIS 1.1, pre-equaliztion was added to DOCSIS cable modems. It was later improved in the DOCSIS 2.0 standard adding more equalizer taps

10 03, 2013

DOCSIS Reed-Solomon Codewords

Mia Colabrese2013-03-10T20:01:38-04:00March 10th, 2013|

How many bytes can a Reed-Solomon codeword bite? In my previous article on DOCSIS Codeword Errors, reader "Sandy" asked how many Reed-Solomon codewords would be required to transport a 1518 byte length of data? This is a very good question and one that I had never considered until I first faced when designing DOCSIS data-layer models in MATLAB. In the example I used in my previous article I chose a word that was 16 bytes long. I did this because it made it easy to draw an 8x8

17 09, 2012

DOCSIS Codeword Errors | What you should know

Mia Colabrese2024-04-19T10:18:35-04:00September 17th, 2012|

Calculating... Calculating... DOCSIS Codeword Errors - You will likely see them DOCSIS correctable codeword errors and uncorrectable codeword errors are available as a metric in most cable operator monitoring tools and Operations Support Systems (OSS). The monitoring tools and OSS generally provide data and dashboards for users to monitor overall network health and then identify a problem when it occurs. Metrics like codeword errors are extracted directly from DOCSIS CMTSs using Simple Network Management Protocol (SNMP) or Internet Protocol Detail Records (IPDR), the later being preferred due to

5 07, 2012

Subscribers get lower data rates than provisioned?

Mia Colabrese2020-06-09T09:36:58-04:00July 5th, 2012|

Why do my DOCSIS subscribers and their Cable Modems get lower speeds than what my DOCSIS config file says they should get? This is a common question that I am asked and it has more than one answer. All too often the RF plant is the first to blame for low DOCSIS cable modem speeds, but in many cases the root cause of the problem can be traced back to the cable modem configuration file and/or the lack of appropriate speed test applications in the headend. Also, some

2 05, 2012

Why is QAM Getting Me Down?

Mia Colabrese2021-08-18T09:11:04-04:00May 2nd, 2012|

64-QAM lower than Analog video on the downstream? 64-QAM lower than 16-QAM on the upstream? Why is a 6.4 MHz channel lower than a 3.2 MHz DOCSIS channel? Someone said there is math for all of this, but man QAM is getting me down! These questions come up in every lecture I give on DOCSIS. Why do QAM measurements show up at different levels on a spectrum analyzer than analog measurements. What's more, why do QAM signals of different bandwidth have different levels? Some of the questions have

27 02, 2012

DOCSIS 3.0 Cable Modem Registration

Mia Colabrese2021-08-17T16:15:14-04:00February 27th, 2012|

This article will discuss the channel bonding process and ultimately the DOCSIS 3.0 cable modem registration process. In order to be able to understand this article, I will make many references to my prior article on Cable Modem Registration which focused on DOCSIS 1.x and 2.0 cable modems.

26 01, 2012

Advanced Troubleshooting in a DOCSIS 3.0 Plant

Mia Colabrese2020-07-02T17:55:04-04:00January 26th, 2012|

If you missed the SCTE Cable-Tec 2011, I am making available my presentation and white paper on Advanced Troubleshooting in a DOCSIS 3.0 Plant. Each speaker had only 20 minutes to cover topics that could easily last hours, so the presentations are understandably brief. Below you will find my presentation in "Slideshare" for online viewing as well as a fully downloadable PowerPoint version. The PowerPoint version also has reader notes attached at the bottom of each slide which you may find useful. In addition, the animations work a little better in the downloadable version.

21 12, 2011

DOCSIS 3.0 Impaired Service

Mia Colabrese2021-08-17T16:00:00-04:00December 21st, 2011|

"Impaired Service" in which case one or more bonded upstream channels are impacted by upstream RF impairments while other bonded channels are not. Since subscriber data is striped (that is broken into pieces and spread across each upstream channel and then re-assembled by the CMTS), some of the data will be lost or have errors while other data will not. Subscribers will most likely notice an impaired condition as upstream data rates slow down due to TCP/IP transmissions and/or VoIP, gaming, teleconferencing and other real-time applications will be noticeably impacted.

7 12, 2011

DOCSIS 3.0 Partial Service

Mia Colabrese2021-08-17T10:25:49-04:00December 7th, 2011|

Partial Service is a new term encountered in the DOCSIS 3.0 MULPI specification and realized in field deployments of DOCSIS 3.0 cable modems using upstream bonding. This was a topic that I touched on in this years SCTE Cable-Tec Expo, but will explore in greater detail in this article. Partial service can be considered a feature because the cable modem will stay online even when one or more upstream transmit channels goes offline.