The nationwide public safety wireless broadband network to be built by contractors to the First Responder Network Authority (FirstNet) on Band 14, which is 20 megahertz of radio-frequency spectrum in the 700-MHz band, promises to deliver advanced wireless capabilities for U.S. public safety agencies. The network will deploy LTE high-speed wireless data that uses orthogonal frequency-division multiplexing as its radio access technology, along with advanced antenna technologies. With AT&T as the FirstNet prime contractor, state and local first responder organizations are making plans on how to deploy FirstNet within their jurisdictions.
LTE-based broadband services represent the next generation for public safety communications. This is not to suggest that legacy land mobile radio systems are going away any time soon, however. For decades, land mobile radio communications have been the mainstay for police, fire and emergency medical services. In fact, many state public safety communications officials expect to maintain their land mobile radio systems even as LTE comes on stream. Their main concern is that LTE many not reach outlying or rural areas of their jurisdictions where land mobile radio still works.
At the same time, there are public safety communications applications better-suited to unlicensed frequency bands rather than occupying capacity on the LTE Band 14 network.
Video surveillance is a good example.
Video cameras — both point-tilt-zoom or bullet-types — installed at intersections and high-traffic spots throughout urban and suburban areas each generate multimegabit-per-second internet protocol (IP) data streams. How much data is generated from each camera depends on the frame rate, resolution and recording interval.
The problem is that rolling up data from all the cameras covering a wide area and delivering those signals to a monitoring center over the FirstNet public safety broadband network would occupy an inordinate amount of network capacity at the expense of other first responder broadband communications.
Wide-area Operation at 4.9 GHz
In this instance, video surveillance traffic is handled better over a point-to-multipoint microwave radio system operating in the FCC-designated, licensed public safety frequency band from 4940 MHz to 4990 MHz (the 4.9-GHz band). A point-to-multipoint deployment such as this would work in parallel with FirstNet.
The main advantage of this approach is that round-the-clock, high-bandwidth services such as video surveillance can be offloaded from the LTE backbone, thereby freeing up capacity for critical communications during emergencies.
Here’s how it works.
The point-to-multipoint 4.9 -Hz system configuration consists of one or more base stations or sector controllers that connect with multiple remote terminals collocated with, and connected with, video cameras at the various monitoring locations within the sector controller coverage area. Multiple sector controllers can be installed at the same tower or mounting location to achieve 360-degree area coverage.
Point-to-multipoint systems in video surveillance applications should exhibit some key performance characteristics, including:
Public safety communications organizations benefit from this approach in numerous ways. They have no spectrum costs because the 4.9-Hz band is available to all local public safety jurisdictions. They save on capital expense because with a high-performance point-to-multipoint system, fewer base stations connect with hundreds of camera sites over a wide area. Such systems have adaptability because cameras are fixed assets and point-to-multipoint systems are designed for connecting large numbers of fixed assets with high capacity, especially for data uploads.
The systems have flexibility because point-to-multipoint wireless links offers the benefit of being able to move cameras with remote terminals to new locations as coverage needs change. Point-to-multipoint systems that emulate fiber-optic performance (Redline calls it Virtual Fiber broadband wireless communications) achieve high performance with high-speed, low-latency
secure connections for real-time video feeds. In many cases, a combination of wireless and fiber cable, where available, provide the best business balance. Easy-to-install, high-reliability radios that require no special technical skills to deploy remote units and that have zero maintenance costs offer the advantage of low operating expense.
At the same time, hauling voice, data or video traffic from the edge of the network back to the core (ergo, the term backhaul) is required in every wireless network whether LTE or land mobile radio is used as the access technology between the base station and the user equipment.
In such networks, all traffic — voice, data or video — ultimately is carried as IP data over the radio frequency to a hub or junction from which these IP signals are routed to a designated monitoring center, a network operations center or an internet peering point.
Fiber-optic cable is an ideal backhaul medium where the cable runs directly to the tower or close to it. However, fiber cable is not available everywhere and is expensive to install, especially in rural areas. In these instances, a point-to-point microwave radio system is the best alternative.
Such point-to-point radio systems are available in licensed and unlicensed frequency bands and can perform at fiber-like speeds. Determining which point-to-point system is right for the application is a function of available spectrum, desired throughput capacity, transmission distance and upfront and operating costs.
First responder organizations can benefit from using point-to-point systems that offer spectrum options, such as systems available in sub-6-GHz unlicensed bands from TV white space (UHF 470-698 MHz) to frequencies between 4.9 GHz and 5.8 GHz for both line-of-sight and non-line-of-sight transmission. Where RF interference may be a problem in certain areas and where line-of-sight transmission is needed, point-to-point systems operating in licensed bands between 6 GHz and 30 GHz frequencies offer a better solution.
Lightweight, compact, all-outdoor radios allow first responder organizations to deploy them on existing structures. The use of the same radio at each end of a microwave hop saves capital expenditures, and simplifies installation and activation. First responders that cover wide areas can realize reliable, high-speed communications over long distances (50 miles or more) with point-to-point systems operating in the 4.9-5.8 GHz band.
In the end, public safety communications organizations can obtain significant operational and economic benefits by deploying readily available, high-performance, cost-effective wireless broadband technologies that complement the FirstNet LTE Band 14 nationwide public safety broadband network.
Louis Lambert is vice president of business development for Markham, Ontario-based Redline Communications, a provider of wide-area wireless networks for the most challenging applications and locations. His email address is [email protected].