Switched video is currently being deployed in many networks across the North America and, although sophisticated, it is not difficult to implement when done so by experts familiar with the technology. Benefiting from a wealth of experience accumulated over multiple deployments, BigBand Networks' professional services team can install a switched video system in just 90 days.

Unlike legacy broadcast systems that deliver all programming to all subscribers, all the time, switched digital video delivers programs only when and where requested by viewers. Additional bandwidth savings are achieved by allowing more than one subscriber within a network node, or service group, to access the same program stream. This concept is shown in figure 1.

Figure 1: Bandwidth savings resulting from programs only being broadcast to
subscribers that are actively watching them

If a subscriber wants to watch a program that is currently being delivered to other subscribers within the same node, the new viewer simply joins the existing switched session. As a result, no additional capacity is consumed by the incremental subscriber.

Switched video, however, is about much more than bandwidth savings. The technology offers benefits that include addressable advertising that more closely matches promotional messages to the interests of viewers, greater personalization of content, the ability to obtain precise viewership data without the use of audience polls by third parties, and more.

Before any switched video installation begins BigBand Networks' professional services team has already provided its customer with a detailed system design and reviewed it with them in depth. Many issues are considered during this pre-deployment phase, including the following:

• What are the cable operator's switched video business goals?
• How much spectrum is available?
• How many programs can, or should, be switched?
• What types of programs can, or should, be put on the switched tier?
• How many QAMs per service group can, or should, be supported?
• How many tuners per service group can, or should, be supported?

BigBand Networks has worked closely with the cable operator to examine each of these issues in detail. Using a variety of tools at its disposal BigBand Networks develops an understanding of the customer's network, including an appreciation for its traffic patterns, an example of which is shown in Figure 2.

Figure 2: Example of the distribution of popular and "long tail" content

Once the switched video system design has been finalized and a purchase order accepted, deployment begins. Being the switched video leader has allowed BigBand Networks to define a deployment process that allows its professional services team to install a custom-designed switched solution in only 90 days.

The following milestones are an integral part of the BigBand Networks' deployment schedule:

1. Validate system design
2. Network deployment plan
3. Facility preparation
4. Equipment manufacture and delivery
5. Headend installation
6. Headend testing
7. Initial hub configuration
8. Initial hub cutover and testing

The typical timeline by which BigBand Networks deploys a switched video system is shown in figure 3.

Figure 3: A typical BigBand Networks' switched video deployment timeline

Validate System Design

Once a purchase order has been received and accepted, the final blueprint for a customized switched video solution is created. This includes completion of a site survey for each office in the switched video network. Other activities included in this stage include the final format of channel lineups for the switched tier.

Network Deployment Plan

Multiple activities are undertaken in this phase of the installation, such as:

• Bill of materials created;
• Long-lead time equipment requirements identified;
• Equipment orders placed;
• Detailed cabling plan defined;
• Service group assignments finalized.

The concluding activity in this phase is a review of the plan by the cable operator. Refinements are implemented as required and final customer approval obtained.

Facility Preparation

Much of the work completed during this timeframe is undertaken by the cable operator. Experience has shown that the ability to deploy a switched video solution in a timely fashion directly correlates to the pace that the cable operator completes these activities. These include the creation of additional rack space, provision of power to chassis and the installation of the incremental HVAC systems, if required.

Equipment Manufacture and Delivery

BigBand Networks and its ecosystem partners manufacture and deliver the equipment needed for the switched video deployment during this phase. BigBand Network pre-stages and loads required software prior to shipment.

Headend Installation

During the previous stage, during which the cable operator has been preparing its network facilities, BigBand Networks has built and shipped the equipment needed at each site, along with obtaining the appropriate devices from ecosystem partners. BigBand Networks' professional services team installs and configures its acquisition / clamping platform, the BigBand BMR (Broadband Multimedia-Service Router), at headend locations during this phase, or installs the necessary software and hardware in cable operator's existing BMRs if capacity is available. The headend management system and bulk encryptors are also provisioned.

Headend Testing

Thorough testing is undertaken by BigBand Networks and the cable operator during this phase to ensure that the headend systems have been correctly installed and configured, and adjustments are made as needed.

Initial Hub Configuration

Deployment of switched video capability at the first network hub begins once equipment has arrived on-site. BigBand Networks' professional services team installs the appropriate number of BigBand Edge QAMs and configures the platforms. Working closely with the customer, BigBand Networks carefully implements a thorough pre-test of the hub.

Initial Hub Cutover and Testing

After pre-testing has been completed the hub is connected to the transport network and the BigBand Edge QAMs are connected to the HFC network. An extensive audit of the system configuration is conducted and, if no errors discovered, the headend management system is cutover and client software downloaded to subscribers' set-top boxes. Finally, BigBand Networks' professional services team carefully test the system using a detailed array of procedures to ensure that its switched video system is operating to the highest standards.

Based on experiences to date special focus should be given to the following areas to ensure the smooth deployments of switched video systems:

• Configuration of the IP network;
• Digital control system reconfiguration;
• Set-top box interoperability issues;
• Naming and numbering conventions.
• Power and HVAC issues;
• Wiring of Edge QAMs.

Configuration of the IP Network

Each of the major components in a switched digital video network requires a control IP unicast address. This IP address must be assigned by the cable operator and must be able to ping the digital control system and set-top boxes from each respective device preferably with a minimal hop count. It is recommended that all unicast IP addresses be in the same subnet. Proper planning and coordination of sub-netting and IP address allocation is recommended to avoid future time consuming and service affecting reprogramming of device IP addresses. A comprehensive IP addressing plan is critical to the pre-testing of the SDV system before it ships to field sites.

Digital Control System Reconfiguration

Keys steps involved in reconfiguring the digital control are the switched video client setup, creation of service application manager and management of multiple ad zones / channel duplication. Proper planning will avoid unplanned delays and downtime, and the need for additional reconfiguration.

Set-top Box Interoperability Issues

The model number and operating system of each set-top box need to be verified before a switched video deployment begins, to avoid interoperability issues.

Naming and Numbering Conventions

Naming and numbering conventions should be established for hubs and service groups before an installation begins. As much as possible a cable operator should attempt to use existing naming convention and wiring of QAM service groups.

Power and HVAC issues

Power at headend and hub locations and HVAC requirements need to be thoroughly engineered and managed as early as possible to avoid project delays.

Wiring of Edge QAMs

Since the amount of cabling that is required in a switched video deployment can be substantial, crossed wires or bad fittings may not show up until all QAMs are launched. Experience has shown that a common wiring plan implemented across all hub locations results in fewer wiring errors. Careful coordination of contractor, cable operator and BigBand Networks' resources maximizes the success of the hub wiring activities and accelerates switched deployments.

Switched digital video is a valuable solution that allows cable operators to reclaim bandwidth and expand program choices. Switched video provide the spectrum needed to offer hundreds of high definition channels, offer