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Simplify software updates for your STBs

Posted: 16 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:set-top-boxes? STB? updating software? set-top-box? video network?

By Filip Vandenbussche

Rapid innovation in STB software is enabling compelling new services for consumers. To deliver those services, however, service providers must ensure that all subscriber STBs are updated with the correct software. This article examines the challenges of updating STB software and looks at some potential solutions.

STB update challenges
Each part of a video delivery system has its operational issues, but managing the STBs at subscriber premises is one of the most challenging. There are five major hurdles to overcome:

  • ? ScalabilitySTBs can number in the hundreds of thousands, and the update system must be able to serve them all in a timely manner without overloading the distribution network.

  • ? VarietyWithin a single network, there are often different makes and versions of STBs scattered among the user base, and the update system must be able to track STB status and ensure that each STB is updated properly with the appropriate software.

  • ? Multi-part software infrastructureEach STB has multiple types of software that require updates, including the operating system (firmware), middleware (user interface, and applications), and content security and digital rights management (DRM) software.

  • ? Multiple update systemsEach vendor of STB software components may have its own update system. For example, middleware and encryption providers may offer their own systems for updating only their products, while STB vendors offer separate systems for operating system updates. This fragmentation also leads to multiple STB databases, so it may be difficult to do overall reports on all STB assets in a network.

  • Lack of integrationThe multiple update products for STBs are not integrated with the overall network management system. Providers must learn and use several different products, and it is difficult and time-consuming to track which STBs have which versions of which software at any given time.

Solution requirements
Ideally, there should be one system that manages all STB updates of any kind. The system should be integrated with the overall network management system so that all STB configurations can be managed via the same interface and console. There are several specific requirements for such a solution:

  • FlexibilityThe solution must be able to deliver any kind of update content to any STB.

    Ease of integrationThe solution should work with any VOD or IPTV system, (cable, satellite, wireless or telco), and should be easy to integrate with the system's overall network management system.

  • ScalabilityThe solution should be able to handle millions of STBs without straining network or server capacity. This requires the ability to deploy it at the head-end and at all regional server locations, with flow-through management back to a central console.

  • ReliabilityThe solution should guarantee 100 percent delivery of software content to every STB with full reporting on update success.

  • Asset trackingThe solution must maintain a single database with up-to-date information on manufacturer, operating system version, middleware version, memory capacity, and feature capabilities for each STB in the network.

STB update alternatives
With these requirements in mind, let's examine the prevailing methods of performing STB updates. There are two basic alternatives:

  • Polling and downloads, where each STB polls a server on a regular schedule and then downloads appropriate updates from central or regional servers

  • Push, where the IPTV or VOD network distributes updates to STBs

Polling and downloads
STB polling is the software update method commonly used by many providers (such as TiVo). Under this system, the STB requires either a standard telephone line connection or an IP connection, and it makes a nightly "connect" to the provider's data center to request and receive updates. These updates are typically scheduled to occur at 3 a.m. or some other overnight hour.

STB polling is a well-proven method of communicating with multiple remote sites, and it has been used to update distributed servers of all types for many years. However, the rising deployment of STBs for new or upgrading subscribers poses three challenges for polling systems:

  • The STB requires a telephone line or live IP connection for updates. Many homeowners don't bother with a constant connection at all, preferring to enable polling only when a screen prompt reminds them that it has been weeks or months since their last update. In these cases, the provider can't ensure the best possible user experience because the STB isn't continually connected to the update system.

  • In many cases since the STB connection is dial-up, connection speeds are low. As update file sizes increase, it takes longer to deliver them. As a result, providers must constantly change polling times and expand the delivery window for each group of STBs. At some point, the polling system won't be able to deliver updates to all STBs during overnight hours.

  • Subscriber growth also poses a challenge, because it often requires the provider to add modem banks to handle the new connections within the required overnight time window.

Polling has worked for many years, but the constraints of time, growing file sizes, and growing subscriber bases will make it difficult for providers to sustain this update system in the future.

Push updates
IPTV and cable TV systems that natively support two-way transmissions can transparently deliver software updates to STBs. Since this system requires no separate connection to a telephone line, consumers receive updates automatically without having to do anything inside their homes. In addition, providers like having the STB update facility integrated with their overall video content distribution and workflow systems.

Typically, these systems use FTP as the file transfer protocol. However, using FTP limits the efficiency and scalability of the push update system:

  • FTP is a point-to-point protocol, so it requires a separate transmission to each STB. This process is extremely system-intensive, bandwidth-intensive, and difficult to manage.

  • As file sizes increase, transmissions take longer, and it takes longer for the entire subscriber base to be updated. Eventually, the delivery window stretches beyond the late night/early morning hours. Providers can reduce the problem by adding more application servers to the data center, but this is expensive and increases management overhead.

  • FTP manages errors by restarting a transmission. In a system with tens of thousands of STBs, there will by hundreds or thousands of such retransmissions, further congesting the network and lengthening the update process.

  • Each STB vendor provides its own update system, so if a provider uses more than one brand of STB, it must also use a vendor-specific update system for each brand.

Push techniques are a more manageable and cost-effective solution for video providers performing STB updates, as long as the system meets all requirements. Now, vendors are rolling out newer systems that use IP multicast technology to address the problems of scaling and efficient management. Multicast-based STB update systems offer several advantages:

  • IP Multicast is a point-to-multipoint protocol. Rather than delivering updates one STB at a time, it can deliver all required updates simultaneously to tens of thousands of STBs in a specific group (by make, model, or software version). As a result, providers can conduct updates with a handful of transmissions rather than hundreds of thousands of transmissions. This eliminates the growing pressure to accomplish updates within an overnight time window, and minimizes congestion on the network.

  • Multicast-based systems can use advanced error-correction mechanisms that broadcast all missing bits in a single session. For example, if 100 STBs out of a 10,000-STB group have missing packets, the distribution software records which packets are missing from each STB's update, and then packages all of the missing packets for all of the STBs that had errors and sends them out in a single transmission. Again, this keeps bandwidth consumption and transmission time to a minimum.

  • Multicast-based systems are extremely cost-effective, using standard Windows/Linux servers and a thin client application on each STB (Existing STBs can be retrofitted with the client via the pre-existing update method).

  • They are massively scalable, because they enable updates for any number of STBs.

  • They can easily integrate with the overall video management system so that all STB status records and update controls are maintained centrally and managed with a single system. IT engineers need no longer juggle two or more vendor-specific update systems and databases, and they have the asset-tracking information for all STBs in one database. This makes STB selection, file selection, delivery scheduling, and reporting much more efficient.

Figure 1: Push updates via IP multicast

As IP-based video systems grow in popularity, STB vendors are increasing the variety and functionality of their products. Concurrently, IPTV and VOD providers are eager to deploy the latest STB features so they can offer the latest and most compelling services while guaranteeing content and access security via content security software patching. Standardized, centralized, and efficient STB update systems that can service heterogeneous software infrastructures across all STBs will be crucial for effective management and ongoing competitiveness of video networks. IP Multicast technology will be central to these new update systems.

About the author
Filip Vandenbussche
is the executive VP of international business development for Stratacache. Prior to joining Stratacache, Filip was the technology and investment officer for the Belgian Foreign Investment agency, where he was involved in many technology transactions related to the triple play solutions for cable operators. Previously, he co-founded a US-based company providing software and hardware solutions for content and video caching or pre-positioning. Filip can be reached at

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