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Case Study 2:

Benefits of ADSG Drive CMTS and RF Upgrades

The benefits of ADSG can drive the re-allocation of CMTS ports, revision of CMTS configurations, re-design and re-cabling of RF, and even additional CMTSs. DTI, now engineering and assuring the readiness of a major MSO’s network infrastructure for a pioneering implementation of ADSG, has clarified how the benefits of ADSG will drive CMTS and RF upgrades, and is providing needed solutions.


ADSG (Advanced DOCSIS Set-Top Gateway) is a new specification from CableLabs developed to enable new and innovative services to be delivered via Set-Top Box as an integral part of television enjoyment. These services include long-envisioned but previously unfeasible applications such as the delivery of voicemail, video-telephony, multimedia email, e-commerce, social networking, and networked gaming, through the TV. ADSG also provides the channel line-up (a.k.a. “channel guide”) information to the Set-Top Box, and in that sense replaces DAVIC (Digital Audio Video Council), which is a 1990s technology promoted by an international consortium, that provides that information in the form of an RF signal that is separately modulated, and is “out-of-band”, from the High Speed Data provided by cable companies for internet access and digital voice services.


Because of its many benefits, especially in enabling new services, cable companies have been investing in the development of the ADSG standard for several years, and are now starting to implement it in their networks. While the benefits of ADSG are well appreciated, it is less obvious that the cost of these benefits can include the re-allocation of CMTS ports, revision of CMTS configurations, re-design and re-cabling of RF, and even additional CMTSs. Here’s how one leads to the other:


The information provided by ADSG includes the channel-line-up (a.k.a. channel guide) that references community (as well as regional and national) programming, emergency alerts (such as storm, flooding and tornado warnings), and other information that is of a local nature. Headends very often serve more than one locality or town (three or four are typical), and these localities are often far enough from each other that the community programming of one is not of interest to another, and emergency alerts for one do not pertain to the other. Yet the locality-specific information provided by ADSG may consume upwards of 2% to 3% of the bandwidth of a CMTS downstream port (roughly 800Kbits/sec. out of 36Mbits/sec.). When a headend serves even three localities, this can amount to 10% of the bandwidth of a CMTS downstream port, two-thirds of which is irrelevant to any one of the localities served, and therefore wasted. In a headend serving more localities, the bandwidth utilization is more wasteful. This leads to a suggested “best-practice” of one CMTS Downstream port per locality served. This leads to the re-allocation and reconfiguration of CMTS downstream ports, which necessitates not only the revision of CMTS configurations, but also the re-design and re-cabling of the headend’s splitters and combiners, which is to say, the Node Combining Plan.


Therefore, the benefits of ADSG may come at a cost of upgrades to the CMTS and RF capacity of headends. Given the new services enabled by ADSG, which explain the cable industry’s commitment to the technology, the headend capacity upgrades are believed to be well worth it. This does underscore, however, the value of having ADSG implementations performed by a technical team that not only can provide expertise in IP Multicast and other IP networking aspects of ADSG, but also expertise in the CMTS and RF aspects of Headend capacity upgrades.


DTI is well-suited for this challenge and is instrumental in pioneering ADSG implementations. In fact, DTI was among the first to understand the relationship between ADSG and the need for headend capacity upgrades. This is a demonstration of DTI’s solutions-orientation and its rare ability to provide the full range of expertise for end-to-end success.



Deployment Technologies Inc. provides end-to-end engineering and deployment expertise for broadband internet, VoIP, and video networks. We work in national backbones, NOCs, regional backbones, headends, VoIP COs, hubs, outside plant, labs, and other network locations. Engineering and EF&I are only two of our many services. Our expertise includes a wide range of equipment, vendors, technologies and applications.

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