Creative Cost Cutting
By Tammy Parker
As cdmaOne expands worldwide, various new approaches and innovative technologies are being deployed or examined that support or enhance the performance of base stations and other network infrastructure. Could they take the bite out of network deployment costs?
Deploying any new wireless communications network is an expensive undertaking, and extending networks into less population-dense areas requires an operators ongoing financial commitment. However, vendors are creating a host of new infrastructure solutions that can help cdmaOne carriers keep costs under control as they aggressively launch and further expand their networks.
These technological advances run the gamut from new
base station designs to alternative network layouts that include the
use of repeaters, high-capacity superconducting filters or intelligent
The need for cdmaOne base stations seems insatiable. In early September 1997, Qualcomm Inc. announced it had shipped more than 1,000 of its QCell Base station Transceiver Subsystems to cdmaOne operators in Asia, Eastern Europe, North America and Latin America. Six months earlier, the company unveiled a CDMA infrastructure chipset that includes a low-power Cell Site Modem and a Frame Interface and Router Module for base station communications. The CSM and FIRM were designed to provide power savings and cost reductions for CDMA infrastructure and test equipment manufacturers.
In September 1997, Motorola Inc. unveiled a CDMA cellular base station transmission system that the company claims can support about twice the capacity of current commercial CDMA networks. The companys SC 4840 base station marks the first use of Motorola CIGs high-density CDMA channel card, which uses a second-generation, application-specific, integrated circuit design that promises increased capacity and enhanced system performance. Further, because the equipment is smaller, carriers can realize savings in equipment room floor space of between 30% and 50%.
The SC 4840 is being deployed first in Japan by carriers DDI and IDO. "Were using some of the aggressive build-up plans of Japan with respect to where they want to see our CDMA networks go as a major driving force internally to challenge ourselves to step up to the next level of performance," says Tony Kobrinetz, Vice President and General Manager of the Advanced Products Division at Motorolas Cellular Infrastructure Group.
The SC 4840 supports the 8 kbps EVRC (enhanced variable rate coder) vocoder as opposed to the 13-kbps vocoder being widely deployed in the United States. The Japanese carriers believe the 8 kbps EVRC "will give them the capacity of eight and the sound quality of 13," notes Kobrinetz. The SC 4840 offers a six-sector CDMA transmit and receive configuration. That combination plus 8 kbps EVRC can produce capacity gains over analog networks of 16 to 18 times, Motorola says.
The SC 4840 also implements Motorolas EMAXX, a channel element technology for higher receive sensitivity that provides better call reception and enables handsets to work at lower transmit power, extending their battery life. Such a feature is especially important in Japan, were consumers are used to small digital cellular and Personal Handyphone handsets that operate on slim, lightweight batteries, Kobrinetz notes.
Independent amplifier houses are also finding success in the cdmaOne market. Sunnyvale, Calif.-based Spectrian has delivered some 350,000 power amplifiers to wireless equipment manufacturers worldwide, including nearly 17,000 cdmaOne amplifiers. The company is shipping cdmaOne amplifiers at a rate of almost 2,000 per month.
Spectrian received two contracts in October 1997 from Northern Telecom Inc. for development and delivery of Spectrians newest cdmaOne single-channel power amplifiers, or SCPAs. The amplifiers, which are being used in Nortels cellular and PCS base stations, have higher performance and increased functionality over their first-generation predecessors, Spectrian says.
Like Motorola, Spectrian anticipates an increasing need for multicarrier power amplifiers, or MCPAs. While such amplifiers are more expensive than single-carrier models an average of $11,000 for an MCPA vs. $2,500 for a single-carrier amp MCPAs give an operator a choice of frequency assignments that can be used as carriers are added to serve capacity.
Spectrian is marketing its MC800-18 100-watt PCS MCPA for
GSM and cdmaOne networks at 1800 MHz. The system integrates
a combiner, amplifier and filter, allowing the devices to
carry multiple modulation schemes simultaneously. And because
MCPAs reduce intermodulation distortion, base stations can
accommodate more customers. MCPAs also require fewer racks
than using several SCPAs, limiting the required site size.
Zucker says PCS operators have been slower than their cellular counterparts to use MCPAs, in part because upbanded product models are new to the market. Further, most PCS operators so far have not had to deal with capacity crunches that require them to add RF carriers.
In June 1997, Qualcomm announced a royalty-bearing licensing agreement with Alhambra, Calif.-based Ortel Corp. to manufacture and sell cdmaOne-based wireless repeater products. At the time, Hal Zarem, Ortels Wireless Communications Business Manager, noted: "Among the many benefits offered by CDMA technology are inherently high capacity and a reduction in the required number of base stations. This leads to technical and economic considerations which create a solid business case for the use of CDMA repeaters, clearly the most cost-effective network element for enhancing coverage."
Sunnyvale, Calif.-based Repeater Technologies, formerly known as Peninsula Engineering, is targeting U.S. cdmaOne PCS operators with its OA 1900C network repeater. The company notes a repeater costs up to 75% less than a base station, requires 90% less real estate for siting and provides faster time to market. "Think about deploying base stations with repeaters in your original network deployment instead of looking at repeaters as hole fill-ins after the fact," says David Bolan, Repeater Technologies Vice President of Marketing.
The company has developed a rural deployment model for a 16-mile stretch of highway. Using 10 cdmaOne base stations to cover the highway would cost $5.5 million in capital costs: A hybrid deployment with four base stations and 14 repeaters would cost $3.6 million. Further, repeaters would reduce recurring costs for real estate, power and T1 backhaul by nearly 40%, another saving of $1.3 million over five years of operation. "To do (a hybrid system for) all the interstate freeways in the United States thats 45,000 miles we could save a carrier $900 million after five years of operation," Bolan claims.
Meanwhile, theres hot news from vendors of superconducting filters,
which may fit quite comfortably in cdmaOne networks. Cryogenically
cooled superconductors, operating at about -300 degrees Fahrenheit,
conduct electrical current with little or no resistance and
provide a high-capacity alternative to conventional RF filters.
Superconductors can let most of the desired signal through
while filtering unwanted signals.
Laves says Illinois Superconductors unique power handling technology allows send and receive filtering. His companys thick film superconducting system can handle 20 watts of power, significantly more than competing thin film superconducting filters, Laves says.
For now, the superconductor companies have realized
the most business in the analog Advanced Mobile Phone Service (AMPS)
market. Analog cellular carriers are finding that superconducting filters
can be used to fill in dead spots on rural highway networks that were
designed to serve three watt mobile units but now are used by customers
with six watt portables. Additional coverage provided by the filters
means carriers dont need to add base stations to close gaps. "In
rural communities, theres no business case to build out networks,"
notes Stephen Garrison, Product Marketing Manager at Green Bay, Wis.-based
Superconducting filters can reduce this "cell breathing" effect by lowering the overall noise, Laves says, thus maintaining coverage and reducing the subscriber unit power level needed.
James Simmons Jr., Vice President of Marketing and Sales at Santa Barbara, Ca11lif.-based Superconductor Technologies, notes superconducting filters can aid carriers faced with collocating equipment with that of competitors. He said Time Division Multiple Access network equipment has been shown to affect CDMA transmissions because CDMA is by nature "a noise-limited system." Filtering out ambient noise from other operators networks can permit collocation and maintain CDMA coverage quality, he says. "Interference, range and size is our mantra," Simmons adds.
Garrison says superconducting filters are especially good candidates for use in cellular networks as they convert from AMPS to cdmaOne in order to keep the digital signals from being dwarfed by the analog ones. He admits, however, that new cdmaOne-based PCS carriers may not see the need for such technologies at this early stage because they are just learning what interference and coverage issues they will have to grapple with in each of their markets.
The superconducting vendors are interested in signing up original equipment manufacturers to market their products. "Up to now, we have primarily sold to operators," notes Laves, but the company is making a concerted effort to market its filters on an OEM basis as well.
The SpotLight system features an array of narrow-beam antennas plus rack-based electronic equipment housed in the cell site. The system interfaces to the base station using standard RF I/O ports. SpotLights omni trunking capabilities let a carrier allocate channels to those areas experiencing the greatest call congestion, using signal strength to determine the best antenna.
"Our first target market for SpotLight is those
wireless operators that are migrating from AMPS to CDMA. In AMPS networks,
operators can use SpotLight as a cost-effective solution for spectrum
clearing," notes Marketing Manager Katherine Petersen. "In
CDMA networks, SpotLight will provide operators with new, more flexible
ways to optimize network performance through interference control, particularly
on the forward link."
With so many new technologies from which to choose, those charged with designing, deploying and building out cdmaOne networks may find themselves a bit overwhelmed. But the fact that there are plenty of advances in base station technologies and numerous alternatives to traditional wireless system design means carriers can afford to be creative as they seek to differentiate their service offerings and provide ubiquitous coverage.