Intelligent optical networks

The technology can increase the survivability and efficiency of video distribution networks.
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Broadcasters, as well as film and television producers, face the common challenge of efficiently transporting high-bandwidth video content over existing networks while maintaining the highest levels of availability. The smallest downtime while broadcasting a live event has serious consequences on advertising revenue and viewer experience. While availability is of vital importance in the broadcasting industry, the ability to transport high-quality video content efficiently is equally important. Broadcasters are constrained by short-range microwave services and costly satellite services, which offer subpar reliability, latency and service quality, while film and television studios are hampered by terrestrial leased-line services and router-based networks that are not suitable or robust enough for HD video delivery. This article describes how an intelligent optical network increases the survivability of broadcast networks and provides efficient and cost-effective transport of high-quality, advanced video content.

Current challenges

Video content is often carried over private lines, ATM, ring-based SONET/SDH, or router-based networks with some type of path redundancy (link protection) and sub-50ms failover time. Despite this carrier-class guarantee of service, these networks cannot survive multiple or simultaneous failures caused by natural disasters, acts of terrorism or human error. (See Figure 1.)

Meanwhile, the demands for new HD and 3-D video capabilities are growing rapidly, creating additional transport challenges. HD and 3-D video are driving significant increases in bandwidth demand that cannot be mitigated through compression because compressing HD and other high-end video results in a loss of signal quality and adds cost and complexity to the network. Addressing these issues, while minimizing the risk of service disruptions, requires a new network approach: a highly survivable intelligent optical infrastructure.

Conventional leased lines and router-based networks are ill-suited for HD video content. HD video files are too large to transport over copper leased lines, and conventional router networks are incapable of streaming uncompressed HD video signals. Since compression leads to a degradation in video and audio quality, many studios distribute HD video content on tape — a costly and inefficient method.

Those who use conventional satellite services have realized quickly that this medium is expensive and fraught with limitations. Satellite uplink/downlink delays can cause unnatural pauses and “talk-over” that impede live interviews. Poor weather conditions can impair satellite feeds, and scheduling transponder time is inconvenient and inefficient.

Distance is another challenge for television and film studios because they rely on geographically dispersed teams to assemble and edit content. A team in one facility may specialize in dialogue editing; another in a second location may add music tracks; and a group in a third city may generate visual effects. Sharing HD content securely and efficiently over hundreds or thousands of miles is a challenge video broadcasters and producers have to overcome.

The intelligent optical network

Highly reliable, intelligent optical infrastructure enables uncompressed SD, HD and 3-D digital video signals to be transported efficiently, regardless of distance. Network complexity can be reduced and operations simplified to achieve better video quality compared to alternative compression strategies. While compatibility with video compression requires more complex configuration and testing to ensure interoperability between encoding and decoding devices, uncompressed video formats adhere to universal standards and can be transmitted using less equipment in the end-to-end video transmission path. This makes installation easier, reduces costs and enhances network reliability and survivability.

An intelligent network is made possible with the latest technology breakthroughs in silicon and software that have unlocked the network potential to carry high-bandwidth video content with the highest levels of availability. Some of these technology breakthroughs, and how they solve the latest challenges faced by video broadcasters and producers, are listed below.

Benefits

  • Capacity: Intelligence is brought to the network by a breakthrough technology called coherent optical processing, which increases network capacity 10 times or more while preserving the existing fiber plant — no network re-engineering, no forklifting, no massive investment. Coherent optical processing unlocks the network potential to handle the large amount of traffic between venues, such as stadiums, and production sites. The capacity unleashed by coherent optical processing allows the core of the video transport network to scale for emerging video interfaces, such as 3G HD and 3-D.
  • Efficient signal mapping through Ethernet or optical transport network (OTN): Video signals can be transported over the network efficiently and cost-effectively while preserving their stringent requirements such as synchronization (clocking), low jitter and low latency. Packet technology advancements allow users to map and merge video signals — such as SD-SDI, HD-SDI, 3G-SDI and DVB-ASI — onto Ethernet (GigE or 10GigE), with a complete set of diagnosis and monitoring tools. OTN allows video signals to be carried transparently over the network, with built-in capabilities such as FEC that increase signal reach and help reduce the number of network elements required between the nodes. The intelligent optical network brings operational simplicity, scalability and efficient bandwidth management (aggregating and switching) capabilities to eliminate bandwidth fragmentation and ensure efficient use of all network assets.
  • Intelligent control plane: Downtime in video networks translates to the loss of millions of dollars in advertising revenue and damages the provider's reputation with viewers. An intelligent control plane acts as the brain of the network, reacting to network changes — such as multiple simultaneous failures, changes in network topology or an increase in latency in some of the network's critical spans — in real time, without any human intervention. The control plane handles and executes the bandwidth increase requests, setting up a new connection between two end points (such as a broadcast in HD between two locations, or a need to transfer a large amount of raw video footage between two studios) and many other tasks required in the TV broadcast and movie production industries, without any intervention. The control plane increases network availability and protects it from the various sources of failures, such as fiber cuts or hardware failures that could affect the services offered to viewers. (See Figure 2 and Figure 3).

Conclusion

An intelligent optical network has a significant positive impact on the video transport network.

  • Enhanced reliability (uptime): The self-healing capability and the ability to survive multiple failures enabled by an intelligent optical network raise video network availability to a new level. Service providers offering network connectivity to broadcasters and TV production firms can capitalize on the high availability of these services as a competitive differentiator.
  • High performance: An intelligent optical network provides deterministic, high-performance, scalable, resilient and fully transparent video transport. High-quality video can be delivered with low latency and low jitter. Emerging video signals such as 3G-SDI and 3-D TV can be transported on the network without putting a huge stress on its capacity.
  • Enhanced flexibility: All the established video interfaces used in the video industry (such as SD-SDI, HD-SDI, DCI [3G-SDI] and DVB-ASI) are supported, allowing content producers to reduce inventory and maintenance costs. Content producers can upgrade to a newer video protocol — such as from HD to 3G HD — in a plug-and-play fashion, without operational churn.
  • Advanced diagnostic features: The combination of video-specific applications and advanced transport networking features, such as fault detection and state signaling, provide superior diagnostic capabilities. The video engineer can now distinguish between a camera failure and a network fiber failure, with different video patterns being generated in the video stream for each type of failure.
  • Better networking agility: The intelligent optical network enables better agility through a quick setup or tear-down of new connections (bandwidth on demand) for events where a large amount of bandwidth is needed for a limited period of time, such as broadcasting from football stadiums over a four-hour period.
  • Enhanced security: In the TV and movie production industries, video content is the most valuable asset to protect from intruders. An intelligent optical network enables wire-speed encryption for any content being transported over the network.
  • Architecture simplification: An intelligent optical network brings operational simplicity, efficiency and cost savings to venues, production sites and backup sites. Seamless scalability, flexibility, efficient bandwidth management and automated operations drive down operating costs while simplifying the network architecture.

The intelligent optical network allows broadcasters to transmit live content more reliably and economically, with higher service quality. Television and motion picture studios can exploit electronic delivery to improve collaboration among post-production teams, eliminate tape-based distribution methods and reduce costs.

In the video broadcast industry, uptime, video quality and operating costs are among the main business imperatives. Film and television producers are in a constant search for a secure and reliable system to share high-bandwidth, high-quality video between geographically dispersed teams. The intelligent optical network enhances network survivability and protects it from multiple failures — a feature that current networks cannot match. The network infrastructure also allows content providers to deliver video in its highest quality while paving the way for a new generation of protocols, and leads to network simplification and cost reduction that set a new economic benchmark for video production and distribution.

Fady Masoud, M. Eng., is an advisor at Ciena's Portfolio Solutions Group — Montreal, Canada.