Figure 1. This diagram illustrates the video feed over broadband wireless between the provider and a broadcaster’s main production facilities. Click here to see an enlarged diagram.
Broadcasters have long viewed wireless as an attractive alternative for selected applications where the cost of adding licensed bands and/or fiber represents a significant expense and inconvenience. But traditional wireless solutions, while adequate for limited data and voice applications, have presented multiple challenges on the broadcast front.
Cellular communications are too slow and cannot provide the bandwidth to transfer large files. Nor can they supply adequate security. Interference, especially in urban areas, can compromise quality of signals. In addition, line-of-sight constraints have made connections difficult, if not impossible. Satellite and microwave services can deliver the necessary functionality, but they are expensive.
In more recent years, 802-16-compliant broadband wireless technology has resolved many of the signal and performance problems. Technology features available in today's systems now enable broadcasters to embrace unhampered, reliable broadband wireless communications in some of the world's most challenging line-of-sight environments.
Several technology features available in some of the new-generation broadband wireless equipment now allow broadcasters to break the communications gridlock found in other wireless options and achieve the real-time video feed capabilities they need. These features include:
- 802.16 compliance, which enables users to specify quality of service (QoS) parameters for the guaranteed levels in throughput, latency and jitter they require for real-time voice, video and data applications.
- High spectral efficiency, which lets users capitalize on available bandwidth.
- Orthogonal frequency-division multiplex (OFDM) technology, which enables equipment to deliver non-line-of-sight (NLOS) and optical-line-of-sight (OLOS) capabilities in urban and rural areas.
- License-exempt frequencies, which expand access options while reducing costs.
- High bandwidth, which offers the capacity to carry IP Ethernet data at rates as high as 48Mb/s or concurrently carry a combination of high-speed IP traffic and up to 4 E1/T1 circuits. A single link can simultaneously carry voice, data and video, and can easily manage the output of several high-resolution cameras.
- The capability to combine 10/100BaseT IP ports and time division multiplexing (TDM) E1/T1 native interfaces, which enables broadcasters to enjoy real-time connectivity for standard computer, private branch exchange (PBX) or voice over Internet protocol (VoIP) equipment simultaneously.
- Extremely low latency, which supports real-time applications, including voice and video.
- Dynamic adaptive modulation and coding techniques, which protect from multipath interference and frequency-specific fading tolerance, and provide error-free links under challenging field conditions.
- Over-the-air encryption, which prevents signal interception and provides security levels not available with 802.11.
With broadband wireless, broadcasters can experience high data throughput and secure connectivity for such applications as contribution feeds, newsgathering, redundancy, distribution feeds and temporary links at major events. Rapid, low-cost setup and tear-down allows for easy relocation when required, and antennas can be mounted on relatively low rooftops or poles — even when line of sight is obstructed. Broadband wireless is the most cost-effective method to provide links over long distances. Equipment can transmit beyond 80km in a single link, while multiple hop links can be set up to connection locations 200km to 320km away.
WNET’s production facilities connect to a transmitter at the Empire State Building using broadband wireless.
One particular application for broadband wireless delivers significant performance and financial benefits. The real-time feed capabilities let broadcasters emulate the full-blown performance of ENG remote units and its equipment at a much lower cost. Camera operators can simply plug their equipment into an encoder, which in turn communicates with the broadband wireless equipment to achieve comparable-quality video images.
For example, a full ENG setup costs a minimum of €200,000 per vehicle. By comparison, a broadband wireless link plus video encoder represents 25 percent of this capital-equipment cost. This capability opens the door for stations with a large contingent of mobile field personnel, limited resources for ENG equipment or occasional needs. Broadband wireless can, therefore, provide inexpensive portable links to complement an existing fleet or eliminate the need for rentals, which can run up to €1500 a day per vehicle.
An added advantage is that the capacity to run two-way links for video and audio feeds enables reporters in the field to file stories and send and receive scripts for editing. This type of two-way capability has not been achievable to date because, for most wireless options, the return path to remote sites is not as robust as the one going out, ENGs are not equipped to provide two-way signals, and cellular simply doesn't have the bandwidth.
Among other cost savings, a broadband wireless solution also reduces reliance on microwave or satellite links. In addition, the low cost of the equipment — and the fact that it can operate over unlicensed bands — makes redundancy for PTP communications much more affordable. Typically, broadcasters can achieve redundancy with broadband wireless operating over an unlicensed band for 25 percent of the cost of more traditional solutions that require license fees.
Public broadcaster Thirteen/WNET, for example, has been exploring the benefits tof broadband wireless. Having successfully deployed a simple point-to-point voice and data link connecting its transmitter in the Empire State Building with production facilities nearly a kilometer away, the station has since been looking into broader-based applications for the broadcast industry. These include using video feeds over broadband wireless as a way to reduce operational costs, to link its sister studios and to deploy cameras in the field at significantly less cost.
In recent pilot applications, the station combined its broadband wireless radio links with video encoders to generate streaming video using an MPEG-4 video feed over IP to the studio. The system used broadband wireless equipment for backhaul functions, acting as a network bridge to allow for real-time streaming of video from mobile cameras operating within a three-mile radius of the studio in NLOS conditions.
While the broadcast industry has yet to explore the benefits of broadband wireless to its fullest, the technology is proving to perform successfully in the world's most challenging broadcast environments. From simple PTP links for voice and data to more complex PMP applications, broadcasters are starting to explore numerous ways to leverage the two-way video streaming capabilities. As applications evolve, broadband wireless promises to deliver significant cost savings to the industry and provide the redundancy needed without compromising performance or quality.
Keith Doucet is vice president of marketing and product management for Redline Communications.
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