Optical wireless speeds HDTV and embedded audio transmissions
The emergence of high-definition television (HDTV) programming and a bevy of corresponding consumer products is driving sweeping changes in the broadcast industry. Television networks already have begun retooling infrastructure to accommodate the requirements of the bandwidth-intense HDTV application, which will affect the industry as indelibly as the advent of color televisions in the 1960s.
As broadcasters roll out more HDTV offerings, more consumers are becoming accustomed to the digital format’s superior picture quality compared with the analog signals they have received in their homes for decades. And they are responding to HDTV in significant numbers. According to the Consumer Electronics Association, this year consumers will purchase more than 18 million digital television sets-a 50% increase over 2005. Further fueling digital TV growth, President George W. Bush recently signed legislation that requires broadcasters to complete their transition to all-digital content by February 17, 2009.
As HDTV momentum intensifies, broadcast engineering teams and systems integration partners are making comprehensive changes to transform studios, cameras, and other equipment to accommodate HDTV. Among the many challenges to fully implementing HDTV upgrades for broadcast infrastructure is securing additional wired or wireless network capacity to carry high-definition digital signals, which can require nearly 10 times the bandwidth of standard-definition transmissions.
In addition to upgrading studios to HDTV, broadcasters are starting to convert auxiliary venue facilities so viewers will not notice a marked difference between studio HDTV shots and material transmitted via the field. Significant complexities arise, however, when taking HDTV out of the studio-especially when delivering the same high-quality, bandwidth-intensive digital content. Optical wireless, a line-of-sight connectivity approach based on free-space optics (FSO) technology, can provide broadcasters with the throughput of wired fiber-optic transmission without the installation difficulties and delays, compression concerns, technical training requirements, and expense associated with other connectivity alternatives.
Optical wireless has already made substantial inroads in enterprise and carrier networks around the world over the past decade as a proven and reliable method for delivering secure, interference-free, and reliable high-speed connectivity. Now, with full-duplex throughput of 1.485 Gbits/sec, specially engineered optical wireless links are supplying the bandwidth required for high-quality, real-time HDTV video and audio feeds.
According to Adam Nepp, director of marketing for 3G Wireless (Severn, MD), a provider of wireless video and audio coverage for all areas of television and film, optical wireless lowers the substantial business barriers to deploying HDTV-quality camera shoots in the field. “Optical wireless has all the pluses of fiber without the need to pull permanent or temporary cabling,” he says. “This state-of-the-art technology enables us to deliver powerful business benefits in terms of cost, capabilities, and simplified operation.”
In providing wireless coverage for a televised golf event, for example, 3G Wireless typically lays more than a mile of fiber-optic cable. The endeavor can require a day or more, as well as considerable logistical and maintenance costs. Optical wireless represents a viable alternative for point-to-point connections traditionally handled by fiber-optic cabling, such as linking a nearby annex location to a primary broadcast studio. Among the major network news programs, the growing trend to include live or taped outdoor segments is accelerating the demand for an easily deployable, high-speed connectivity alternative to laying permanent or temporary fiber in busy metropolitan areas where trenching is out of the question.
Another major advantage of optical wireless is the ability to send uncompressed video transmissions with no frame delays. A new technology breakthrough in optical wireless is a high-end product that meets HDTV standards of 1.485 Gbits/sec and is fully compatible with the HDTV Serial Digital Interface (HD-SDI) transmission industry standard. For Scott Wohler, chief engineer at 3G Wireless, this technical innovation makes optical wireless especially appealing to broadcasters. “The ability to send a full stream of raw video offers many more post-production options for taped segments while also ensuring high-quality live remote transmissions,” he says.
In contrast, remote wireless links based on lower-speed radio frequency (RF) or digital microwave technology do not have sufficient bandwidth to carry raw video. As a result, RF-based links require compression using encoding technologies based on standards for moving images and audio established by the Motion Pictures Expert Group (MPEG). The major shortcoming of compression technologies is latency-slight, millisecond delays-which can prove unacceptable when delivering live HDTV broadcast coverage.
Aside from bandwidth limitations, RF-based connectivity also requires RF spectrum licensing. When setting up temporary links for sports programming or special events, broadcasters need to obtain a license or work within the licensed spectrum provided by outside RF provisioning partners. However, securing spectrum licensing for prolonged periods is difficult at best and most likely unattainable, which presents problems for longer-term, annex studio broadcasts. Additionally, unlicensed RF links are prone to interference issues, especially in metropolitan areas.
Optical wireless, on the other hand, can be operated worldwide without a regulatory license, which is an advantage for broadcast networks seeking semipermanent links to annex studios or field locations-typified by the outdoor segments frequently used by regular network news programs.
“Optical wireless lends itself to plug-and-play deployments that can be operational within minutes instead of days,” says Nepp. “Moreover, these installs can save up to 50% of the equipment and engineering expenses involved in more traditional solutions.” In the case of HDTV, streamlined deployments and cost-effective, high-speed connectivity provide unprecedented flexibility to accommodate a variety of applications.
To date, sports, entertainment, and network news programming are leading the HDTV revolution. More than 60% of NBC’s coverage of the 20th Winter Olympics in Turin, Italy, was broadcasted entirely in HDTV. ABC produced portions of its Super Bowl XL coverage in HDTV, which also included more than two-dozen high-definition commercials. ABC has led broadcast news programming divisions by broadcasting its popular weekday show “Good Morning America” entirely in HDTV since October 2005. The show is the first regularly scheduled commercial network news program to be delivered daily in that format. ABC’s sister network, ESPN, also has embraced high-definition for its in-studio programming.
As these major television networks increase their regularly scheduled ventures out of the studio, optical wireless will enable them to move and react very quickly. In fact, the emergence of optical wireless rapid-deployment kits, which consist of rugged rolling travel cases containing optical wireless transceivers, power sources, and heavy-duty mounting stands, accelerates fast and efficient temporary communications. These compact, portable devices can be deployed-and redeployed-without needing a group of technicians or licenses.
3G Wireless gained first-hand experience with the ease and simplicity of high-speed optical wireless when a major U.S. television network required transmission of HDTV coverage from an annex studio location in New York City. Fiber immediately was out of the question due to the impossibilities of deployment in a major metropolitan area, including obtaining rights-of-way, lengthy time schedules, and exorbitant costs.
The team also evaluated different RF options before determining that bandwidth and compression limitations would affect broadcast quality adversely. After ruling out fiber and RF solutions, 3G Wireless experts next turned to an optical wireless system designed specifically for high-definition broadcast video and embedded audio for HDTV.
In particular, the TV network wanted to take advantage of “remote cam” shots without needing a team of on-site wireless technicians to ensure operation. With the HDTV-compatible device, 3G Wireless provided the network with a method of delivering uncompressed video in a portable, plug-and-play device easily used by a cameraman at the remote location. Each day, the cameraman sets up both his camera and the optical wireless link at the annex studio, and within minutes is able to transmit HDTV-quality video from the field.
Another field application for optical wireless in the broadcast industry is “remote hopping” to backhaul broadcast coverage of outside sporting events and tournaments to a central transmitter. Optical wireless also provides both the portability and bandwidth capabilities required for carrying the large-format video featured on the jumbo-sized screens favored at concerts and conventions.
Clearly, broadcasters are learning what scores of enterprises and carriers have known for years: Optical wireless offers countless performance and cost advantages over fiber-optic cable and lower-speed RF communications in many applications. Optical wireless surpasses all the other connectivity options in terms of ease of use, portability, cost, and capacity. Ongoing advances in bandwidth performance will ensure that optical wireless continues to play an ever-increasing role in propelling the HDTV revolution.
Randel Maestre is director of product management for LightPointe Communications (San Diego; www.lightpointe.com), a designer and manufacturer of outdoor wireless products.