Transporting Bandwidth Congestion

Communications networks are growing more congested as consumers increase wireless usage and as companies generate and transport more data. As this bandwidth grows increasingly congested, service providers are constantly seeking relief. Carriers need innovative ways to break the logjams.

Wireless T1s are one effective remedy for moving data and voice traffic from one point to another. Wireless T1 systems can help free up links between cell sites and switching centers. The high-capacity systems can deliver one or more T1 (1.5Mb/s) datastreams, a capacity equal to landline T1s. The technology is useful in various settings, but is most effective as an alternative to wire in transporting large volumes of voice, data and video.

Wireless T1s, for example, connect buildings on corporate campuses, cell sites and switching centers and link central offices to remote access points. Operators of offshore oil drilling platforms often employ the technology to ship data and voice traffic from a rig to on-shore PBX systems or LANs. Utilities use wireless T1s to carry high volumes of information about energy production to central data-processing facilities. Distance learning, the transmission of video and other data from a classroom to remote sites, also has emerged as a popular application.

In general, wireless T1s work well where lines are impractical to install, such as in rocky soil where digging is difficult, in mountains or heavily forested areas, over water or other inaccessible locations.

There are many applications that require large volumes of data to be transported between multiple locations of a given company or organization. Data is becoming easier to gather, and computers are more commonplace. So carriers need ways to move data around. As capacities increase, wireless T1s are one way to address the issue.

There is no mystery behind the crowding of telecommunications networks, both wireline and wireless. The proliferation of the Internet has flooded telephone lines with data. Companies, government agencies and non-profit organizations are generating and moving more data than ever within their organizations and to customers and suppliers. Although the majority of that traffic travels over wireline networks, the wireless picture is much the same as the industry continues its exploding growth rates.

The number of wireless subscribers has increased at a compound annual rate of 40% over the past three years, and that growth shows no signs of slowing. PCIA estimates that the number of wireless subscribers will reach 84.5 million by 2000. Clearly, massive network construction is necessary to keep up with that explosive subscriber growth. Wireless T1s can help fill the gap to accommodate the extraordinary requirements of expanding communications.

Over the past several years, many carriers have extended connectivity capacity with spread-spectrum wireless T1s. Most existing plants have a single-T1 bandwidth. Now carriers are looking to increase capacity further. For a cost-effective solution, you can simply upgrade to newer technology: multiple-T1 products for existing single-T1 radios. By substituting products operating on the same frequency, you can use existing transmission lines and antennas to expand capacity immediately and inexpensively.

T1 radio manufacturers offer a variety of hardware and software options for carriers wanting to offer these services. Versatile T1 systems allow you to install the RF converter portion of the spread-spectrum radio in a rack for easy access or mast-mounted on a rooftop or tower to maximize performance. In addition, you can use different channel plans and spreading codes for interference protection.

WIRELESS T1S PUT TO USE Some wireless service providers already are realizing the benefits of using dual-T1-capacity products. Southern Company, a utility holding company, was one of the industry's first adopters with Southern LINC, its commercial, digital wireless communications service.

Southern LINC, which combines Instant LINC (2-way radio), phone service, numeric and text paging, and mobile data in one Motorola device, was designed to meet the communications needs of commercial customers and Southern Company's five Southeast power companies. Covering more than 120, 000 square miles across Alabama, Georgia, Southeast Mississippi and the panhandle of Florida, Southern LINC has customers in industries such as emergency and governmental services. They include businesses with mobile work forces that have a high percentage of internal communications or use two or more communications devices -- such as 2-way radios, pagers and wireless phones.

Southern Company has invested millions of dollars in building the Southern LINC network. That infrastructure includes wireless T1s. In an effort to expand capacity, Southern Company successfully tested preproduction, unlicensed, spread-spectrum, wireless, dual-T1 units as replacements for existing single-T1 systems in the Southern LINC network. After testing, Southern LINC installed dual-T1 units as high-capacity replacements for some existing single-T1 systems. Southern uses Adtran's 2T1 Tracer system to link many of its cell sites where it's not feasible to establish leased landline connections.

Typically, the company had used spread-spectrum technology for these links, but growing communications traffic demanded a solution that provided a "bigger pipe," said Mardis Howell, Southern Company services transport engineering unit senior analyst. To handle the communications needs of its operating companies and Southern LINC's external customers, Southern needed more capacity than a single T1 offered.

Howell said he and his staff were immediately interested in dual T1s because they supplied the bandwidth of two T1s at a comparable price without a lengthy licensing and frequency-coordination process.

"It keeps us from having to install a higher-capacity licensed radio or lease additional T1s. Those things can be expensive and take time away from serving customers," Howell said. "The second T1 is also icing on the cake as far as capacity is concerned."

WHEN TO USE WIRELESS T1S Wireless T1s are part of the solution, but there are several issues to consider when deciding whether to use the technology. First, you must consider the signal path the T1 system will travel. You need a clear line-of-sight path to ensure acceptable performance and prevent dropped signals. Once you determine there is a usable path, you must align directional transmission and reception antennas to point directly at each other. Installers can pan the antennas back and forth mechanically, and use a VT100 terminal, laptop computer or radio test equipment to monitor the antenna alignment and determine when they are positioned to deliver maximum performance.

Likewise, you need to locate the equipment on a proper site, preferably a building top or tower. The site also must have sufficient power to run the equipment and must offer access through walls or roofs to run transmission lines and power cables.

The FCC requires that you have trained professionals install wireless T1 systems. Although actual installation and implementation are simple, certain aspects demand knowledgeable attention, including antenna placement, supplying power and assuring proper grounding.

Another benefit of these digital spread-spectrum radios is the minimal routine maintenance that is required. Some wireless T1 products simplify maintenance by performing self-diagnostic checks. They can alarm you to problems. Systems also can advise you when status is normal and when there is a problem. For example, alarms and status checks are carried out through a separate maintenance channel embedded in the data stream that provides far-end configuration, monitoring and control functions without affecting T1 performance. All test, status and configuration information is accessible via a menu-driven terminal interface or through front-panel controls.

Wireless T1s are available as a complete system based on the individual demands of the installation, format and redundancy requirements.

Systems integrators and large end users can order individual components for spares and replacement parts.

Systems that operate in the FCC's unlicensed 2.4GHz to 2.4835GHz industrial, scientific and medical band can be installed quickly without protracted and expensive frequency coordination. Once installed, wireless T1s can provide point-to-point connections of up to 30 miles.

MEETING DEMAND As the demand for bandwidth grows, companies are pushing technology to keep pace. New-generation, dual-wireless-T1 products are now available to deliver the capacity of two traditional T1 lines. Southern LINC already has seen the possibilities. If you are looking to increase capacity, you have an immediate option available to meet your needs.