Cisco Headend System Release 2.7 Release Notes
Chapter 2 SDV: The New Optional Feature in SR 2.7
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Traditional Linear Broadcasting
The following diagram illustrates the traditional method of "linear" broadcasting
over HFC. Some "narrowcasting" is done in that not all hubs need to carry all the
same content. However, any broadcast content that is selected for that hub is
transmitted continuously to all subscribers.
over HFC. Some "narrowcasting" is done in that not all hubs need to carry all the
same content. However, any broadcast content that is selected for that hub is
transmitted continuously to all subscribers.
This method of linear broadcasting is extremely simple and has worked reliably and
cost-effectively for both cable service providers and consumers. However, increases
in channel offerings and higher-bandwidth programming content, such as high-
definition (HD) programming, have resulted in a greater demand for bandwidth.
This bandwidth demand cannot be readily satisfied by continuous access network
upgrades and rebuilds. It is no longer cost-effective to continuously increase
bandwidth for services with low viewership. Cable service providers have a need for
a new architecture that will reclaim wasted bandwidth and improve the subscriber's
experience without requiring endless bandwidth expansion. SDV represents that
new architecture.
cost-effectively for both cable service providers and consumers. However, increases
in channel offerings and higher-bandwidth programming content, such as high-
definition (HD) programming, have resulted in a greater demand for bandwidth.
This bandwidth demand cannot be readily satisfied by continuous access network
upgrades and rebuilds. It is no longer cost-effective to continuously increase
bandwidth for services with low viewership. Cable service providers have a need for
a new architecture that will reclaim wasted bandwidth and improve the subscriber's
experience without requiring endless bandwidth expansion. SDV represents that
new architecture.
The Switched Digital Solution
The advent of SDV technology promises to fundamentally change the way the
industry delivers digital entertainment. With SDV, service providers have the ability
to offer a wider variety of programming while managing HFC network bandwidth
in a sustainable way.
industry delivers digital entertainment. With SDV, service providers have the ability
to offer a wider variety of programming while managing HFC network bandwidth
in a sustainable way.
In a manner similar to a telephone system, which switches a smaller number of lines
upon the demand of a larger number of customers, the SDV architecture switches
only selected content onto the HFC upon the demand of one or more viewers. Thus,
content that is not requested by anyone in a service group does not occupy HFC
bandwidth or require edge modulator resources.
upon the demand of a larger number of customers, the SDV architecture switches
only selected content onto the HFC upon the demand of one or more viewers. Thus,
content that is not requested by anyone in a service group does not occupy HFC
bandwidth or require edge modulator resources.
With SDV, popular content continues to be broadcast continuously, while less
popular content is held back and transmitted only upon request. Unlike video-on-
demand (VOD), with SDV (after the content is transmitted) that stream is shared by
any subsequent viewers requesting the same content within the same service group.
popular content is held back and transmitted only upon request. Unlike video-on-
demand (VOD), with SDV (after the content is transmitted) that stream is shared by
any subsequent viewers requesting the same content within the same service group.
SDV also provides access to broadcast service while VOD is retrieving stored content
from a server. As a result, SDV still uses the broadcaster's schedule to determine
when a program airs.
from a server. As a result, SDV still uses the broadcaster's schedule to determine
when a program airs.