DOCSIS White Paper(s)

What’s Next for DOCSIS 3.1: Modulation Options and Impacts

A second technology in the DOCSIS 3.1 standard is called Low-density parity-check (LDPC). This replaces the older Reed-Solomon forward error correction with a much more advanced error correction. LDPC is an advanced error-correction algorithm and models have shown that by using LDPC 4096-QAM will operate just like 256-QAM under the same impairment conditions. This is very good news for any technician with concerns about troubleshooting a plant with 4096-QAM. Once LDPC is in place, 4096- QAM in OFDM will be just like 256-QAM without OFDM!

DOCSIS Pre-Equalization: Vastly Powerful, Often Undervalued

This paper will first provide a brief primer on DOCSIS to establish a baseline for the document. Next the paper will examine what is DOCSIS pre-equalization. How DOCSIS pre-equalization works and how DOCSIS pre-equalization can be extended. In the greater context of the paper, the reader must consider the implications of the extensions of DOCSIS pre-equalization. In section 5, details will be provided on how DOCSIS pre-equalization can be used to identify plant impairments and locate those impairments to within a few feet. This turns every cable modem in your network into a very powerful troubleshooting device. The implications are that DOCSIS pre- equalization as a troubleshooting tool will change the cable industries maintenance practices, significantly reduce maintenance costs and dramatically improve subscriber satisfaction with overall service performance, for data and video.

EdgeQAM Modulators

In a DOCSIS white paper Seldom is there a discussion around video, switched digital video (SDV), video-on-demand (VOD) or DOCSIS 3.0 that does not mention the edgeQAM (eQAM) modulator. In the past couple of years, eQAM has rapidly become part of our vocabulary.

Never Underestimate the Importance of IP Troubleshooting It’s Not Always the RF

DOCSIS white paper on Contemporary troubleshooting of Data over Cable Service Interface Specifications (DOCSIS®) requires a combination of RF and IP disciplines. DOCSIS begins at the RF domain where digital signals are modulated and transported across the Hybrid-Fiber Coaxial (HFC) network between two end points. Theses devices consist of a Cable Modem Termination System (CMTS) and cable modem(s). The transmission of digital data forms an IP network, which relies on many common networking devices, such as Dynamic Host Control Protocol (DHCP), Trivial File Transfer Protocol (TFTP), Time of Day (ToD), and Address Resolution Protocol (ARP). Impairments and communications breakdown can and do happen at both the RF and IP domains.

Troubleshooting Voice-over-IP (VoIP) / Impairments in a DOCSIS Network

This DOCSIS white paper will discuss troubleshooting Voice-over-Internet Protocol (VoIP) in a DOCSIS® (Data-over-Cable System Interface Specification) network. It will begin with the method by which cable operators provide voice services over a data network. This is will start with DOCSIS and VoIP primers in order to provide a common foundation of terminology and understanding of the subject matter.

Why should you care about DOCSIS?  VoIP is why

This DOCSIS white paper will investigate the building block of VoIP – the DOCSIS network. In order to obtain the revenue generating opportunities of VoIP, it is essential to understand and troubleshoot a DOCSIS, (Data-Over-Cable Service Interface Specification) network. If all of the elements of the DOCSIS network are working properly, from RF to IP, then VoIP should be elementary, however if there are any RF impairments, DOCSIS protocol impairments, or IP data routing anomalies, then VoIP deployments can be disastrous.  Understanding and identifying these impairments will require new technologies and understanding new concepts.

RF to IP – The Top Most Common DOCSIS Killers and How to Identify Them

This DOCSIS white paper will discuss the most common impairments in a DOCSIS® (Data-over-Cable Service Interface Specification) network and how to identify them. It will begin with the method by which cable operators provide data and voice services over a data network. This will start with DOCSIS and VoIP primers in order to provide a common foundation of terminology and understanding of the subject matter.

Getting a grip on DOCSIS Network reliability equals increased revenue

Data-Over-Cable System Interface Specification (DOCSIS) is the vehicle for cable operators to obtain immediate revenue-generating opportunities such as broadband data, voice-over IP, IP video-on-demand, and countless emerging IP-based technologies. These growth channels rely on cable operators obtaining and retaining subscribers.  Subscriber satisfaction with new services is a direct function of DOCSIS network reliability. Improving DOCSIS network reliability requires new skills and new test equipment, in addition to the skills and test equipment the industry possesses today.  

This DOCSIS white paper provides a working knowledge of DOCSIS networks, the types of  impairments that exist in DOCSIS networks, and strategies employed in identifying the impairments in the physical plant.

Improving DOCSIS Reliability

Data-over-cable System Interface Specification (DOCSIS) is the vehicle for cable operators to obtain immediate revenue generating opportunities such as Broadband Data, Voice over IP, IP Video-on-Demand, and countless emerging IP-based technologies. These growth channels rely on cable operators obtaining and retaining subscribers. Subscriber satisfaction with new services is a direct function of DOCSIS network reliability. Improving DOCSIS network reliability requires new skills and new test equipment, in addition to the skills and test equipment we possess as an industry today.

Cable-Tec Expo 2009 Troubleshooting in a DOCSIS® 3.0 Plant: What You Need to Know

Once a foundation has been provided, the paper will focus on three (3) high level VoIP impairments, Packet Loss, Delay (also referred to as “Latency” interchangeably), and Jitter. These three components are responsible for nearly all VoIP call degradation, but the underlying manifestation of the components may be the result of a complex number of factors in the distribution network. While some of the impairments can be corrected in the transport mechanisms supporting the VoIP call, some cannot. This leads to the need for advanced techniques of minimizing the effects of packet loss, delay, and jitter. If the impairments cannot be minimized below a certain threshold, the user (hereon referred to as the “caller”) will experience poor voice call quality, analogous to many Public Switched Telephone Network (PSTN) related impairments, such as echo, noisy background, distorted voices, and talker delay. Minimizing these perceived impairments is what will ultimately win or lose the battle for voice services by cable providers.

WHEN RF AND IP CLASH – THE REALM OF DOCSIS & VOIP TROUBLESHOOTING

Contemporary troubleshooting of Data over Cable Service Interface Specifications (DOCSIS®) requires a combination of RF and IP disciplines. DOCSIS begins at the RF domain where digital signals are modulated and transported across the Hybrid-Fiber Coaxial (HFC) network between two end points.  Theses devices consist of a Cable Modem Termination System (CMTS) and cable modem(s). The transmission of digital data forms an IP network, which relies on many common networking devices, such as Dynamic Host Control Protocol (DHCP), Trivial File Transfer Protocol (TFTP), and Time of Day (ToD). Impairments and communications breakdown can and do happen at both the RF and IP domains.

From Cobble Stone to Concrete, VoIP Rides on the DOCSIS Highway

All cable modems are pretty simple devices, which mean they are pretty easy to troubleshoot once you understand how they should work. So your subscriber buys a cable modem at their favorite electronics store, (hopefully) registers it with their local cable system, connects the RF coax and plugs in the power. The following steps are what the cable modem should do:

Cable Modem Registration Process 

In this DOCSIS white paper, we are going to closely examine the cable modem registration process, break it down into its fundamental parts, and understand how it should work. We will then look at the registration process as seen from the RF plant using a DOCSIS Protocol Analyzer (DPA). Finally, we will discuss some common non-RF DOCSIS and IP problems that can be readily identified with a DPA

DOCSIS Hierarchy