ESMR: Integrating networks to provide commercial service
Using digital technology, a utility provider creates a revenue-producing ESMR operation that also satisfies its own internal communications needs at reduced cost.
Among wireless communications archetypes, utilities often build and have direct control over their own private communications systems (“Utilities As SMRs: Using Simulcast Trunking,” MRT, July). Nor is it unprecedented for businesses to take advantage of unused system capacity by selling it as a commercial provider, as the birth of Sprint demonstrated in the 1980s. However, the Atlanta-based Southern Company, the largest U.S. electrical producer, embarked on a new course four years ago when it deliberately created an enhanced specialized mobile radio (ESMR) entity that would be principally a commercial provider, for which it would be a customer.
That course was sustained at the end of July when Southern’s board of directors committed an additional $100 million to the continued development of its Southern LINC (long-range integrated network communications) digital communications system through the year 2005. The investment is earmarked for a variety of infrastructure improvements to improve coverage, to add cell sites and to enhance service, features and software.
“Southern LINC is currently exceeding its performance expectations, and we’re confident it will continue to do so,” said A.W. Dahlberg, Southern Company’s chairman. “The board believes this $100 million investment will ensure Southern LINC’s development as the premier wireless business communications system.”
Southern Company comprises Alabama Power, Georgia Power, Gulf Power, Mississippi Power and Savannah Electric. It also supplies electricity in eight countries and provides other energy-related serv-ices, ranking 65th overall in the Fortune 500 list of top American corporations. Southern Company formed Southern Communications Services, which operates the Southern LINC system, in 1993, when construction began. Commercial service started in February 1996.
“We have customers in virtually every SIC (standard industry classification) code,” said Julie Toland, Southern Communications Services’ director of marketing. Toland said typical subscribers are businesses with a high percentage of internal communications, particularly those requiring access to both dispatch and private call functions.
Toland said that when Motorola announced its integrated digital enhanced network (IDEN) technology (see sidebar below), Southern realized it could be used to support a commercial business and bring in additional revenue. The availability of the digital technology was the catalyst for replacing the older radio network that was in place. By initially planning to enter the commercial market, Southern Company was able to create cost-effective access to a digital system to support the internal communications needs of its businesses.
About 78% of the traffic on the network is commercial, Toland said. The remaining airtime is billed to the utilities at a lower rate than could have been obtained from a third-party provider. The network has also captured part of the government and public safety market, such as ambulance services, because the level of system reliability required to support utility communications is comparable to those needs (see sidebar on page 28). Because the utility network required penetration into rural, as well as metroplitan, areas, this became an advantage in offering commercial service, which is often not available in those areas, Toland said.
Southern LINC coverage extends into four states, taking in nearly all of Alabama and Georgia, southeast Mississippi and the Florida panhandle. Infrastructure for the 120,000-square-mile network includes a system of 325 towers, designed to withstand 105mph winds and a half-inch of ice loading. Transmitter facilities include backup generators, eight-hour batteries and access security.
The RF coverage is subdivided into 12 geographic zones. The company offers its customers five service area choices, depending on the needs of a particular business.
Two-way dispatch, phone service and paging services can be purchased individually. At the end of 1996, Southern introduced a proprietary paging software, Textlinc, designed to interface with its digital system. The messaging system has also been extended to allow Internet-based messages sent through Southern LINC’s Web site.
Most of the subscriber equipment offered by Southern LINC consists of Motorola devices, including five handsets, offering 0.6W or 1W of output power, which can be used for private, dispatch, multiservice or industrial applications. Three versions of 3W mobile units are also offered, as well as four types of 3W desktop control stations.
Motorola’s IDEN (integrated digital enhanced network) is a wireless digital technology that integrates two-way radio, full-duplex telephone interconnect, short message service and data transmission into a single handset.
To increase spectral efficiency, IDEN maximizes channel capacity by means of three proprietary Motorola technologies:
* VSELP (vector sum excited linear predictors) voice coder (vocoder) technology compresses voice signals and digitizes voice data to reduce the transmission rate. Motorola originally designed the system with a 4.2kbps vocoder that samples and digitizes voice signals to allow six time slots per 25kHz radio channel (6:1), which is still available for data and dispatch communications. In 1996 Motorola created an “enhanced” IDEN by reducing the number of voice slots to three (3:1). An 8kbps vocoder was added to double the sampling rate and improve voice quality, particularly for telephone interconnect. (“3:1 Time Division Supports Premium Digital Voice Quality,” MRT, October 1996.)
* M16QAM modulation technology increases data density, transmitting at 64kbps, enabling efficient data transmission in a narrowband channel.
* Time-division multiple-access (TDMA) divides the radio channel into multiple communication pathways through which segmented voice and data “packets” can be assigned a time frame and transmitted. The packets are reassembled at the receiver into the original information sequence.
Over the weekend of July 18-20, Hurricane Danny whirled out of the Gulf of Mexico and made landfall on the Gulf Coast. Bringing heavy winds and torrential rainfall, the hurricane moved slowly from Grand Isle, LA, to the Florida panhandle. It hit Mobile County, AL, on the morning of the 19th, where its winds were clocked at 80mph and it unleashed 30 inches of rain.
Southern LINC’s network was used by the Alabama Emergency Management Agency (AEMA) to coordinate rescue and relief efforts during the storm. Scott Adcock, public information manager for AEMA, said the Southern LINC system was used almost exclusively for the agency’s communications.
“Virtually all of Alabama’s key officials kept Southern LINC handsets by their sides throughout Danny_the governor, EMA director, Department of Public Safety director and the Adjutant General of the Alabama National Guard, as well as the Department of Transportation,” Adcock said.
Previously, AEMA had used cellular phones and older UHF radios but had experienced problems with dependability and mobility in the field. Using the ESMR system during the storm, AEMA designated a talk group in the hardest hit areas to quickly relay information to multiple points.
“Southern LINC was essential in our search and rescue missions.” Adcock said. “When local 9-1-1 operators received information from residents about rising waters, they relayed it to our county EMAs, who then used LINC handsets. This gave us an important edge in providing additional support to the National Guard, volunteer fire departments and other volunteers.”