Linear Unicast Ecosystem
The linear unicast ecosystem is depicted in Figure 6:
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Figure 6: A linear unicast ecosystem
Linear unicast is based on Switched Digital Video. When a subscriber switches to a channel, the set-top box requests the tuning information for that channel from the SDV server. The SDV server, in conjunction with an Edge Resource Manager, decides whether that request should be fulfilled using a shared stream (multicast) or a dedicated stream. For a dedicated unicast stream, the SDV server creates a unicast session on the Edge QAM (EQAM) and instructs the Media Services Platform to create a unicast stream for that subscriber going through the EQAM. This process is similar in nature to the creation of a VOD session from a VOD server through an EQAM. It is completely transparent to the STB, which continues to view this as a regular SDV session setup.
During an ad break the ADS may instruct the Ad Decision Manager (ADM) inside the Media Services Platform on how to match each ad version with the unicast streams originating from the platform.
Linear unicast changes the bandwidth allocation model for cable from the traditional supply model -which is based on the number of channels offered, to a demand model that is based on the number of active tuners. In general, unicast is likely to require more narrowcast resources within a Service Group. However, there is no need to transition to a full unicast model overnight. MSOs can gradually migrate their channels from multicast to unicast over time, selecting specific channels or even specific tuners for unicast while keeping the rest in Multicast. This concept is also known as Selective Unicasting.
Conclusion
As operators look to advance their advertising offering and get to the promised land of 1:1 addressability, interactivity and detailed measurements, they are faced with the burden of existing ecosystems, business practices, and uncertain economic climate. They need to be able to gradually migrate from their existing zone-based infrastructure to a full unicast delivery model, while maintaining their revenue stream, and minimizing their CAPEX as well as OPEX.
Virtual zoning provides a logical next step that takes advertising forward, provides a better level of addressability without requiring additional spectrum, and keeps CAPEX at low levels. It is a natural step on the path to linear unicast. While SDV was originally deployed by MSOs to reclaim spectrum and allow introduction of new services on top of the existing Hybrid Fiber/Coax (HFC) plant, it now becomes a powerful tool for reporting as well as a vehicle for migrating from multicast to unicast, which is viewed by the industry as the promised land of television personalization.
About the author:
Yaron Raz is Director of Video Solutions Marketing at BigBand Networks. Yaron is responsible for defining innovative products and solutions in the areas of Personalized TV, Advanced Advertising, and Switched Digital Video. Throughout the course of his 18-year career, Yaron has held various technical, marketing, and R&D roles in the telecommunications industry. Before joining BigBand, Yaron served in various Marketing and R&D management positions for Nokia Siemens Networks, where he has been a significant contributor to the introduction of the first Carrier Ethernet Switches in the market place. Previously Yaron served in R&D positions for IBM and Intel. Yaron holds an MBA with honors from the University of Herriot Watt in Edinburgh UK, and a BSc with honors in Electrical Engineering from the Institute of Technology, Israel.
He can be reached at Yaron.Raz@bigbandnet.com.
