Top 10 CommScope Innovations: Extend-A-Cell Repeaters

Thomas_Kummetz_01--thumb Thomas Kummetz December 15, 2016

Extend-a-cell-compressedNote: we have been revealing in recent blog posts the top 40 innovations made by CommScope (or one of its acquired companies) as part of our 40th anniversary celebration. We continue today by revealing an innovation from the final grouping of innovations—the top 10—which are being announced in alphabetical order. These are our all-time greatest product and technology innovations. You can also review the complete list of innovations we’ve revealed so far and read more about the overall program and selection process in this November 4 post.

CommScope’s Top 40 Innovations—Grouping 1-10

Extend-A-Cell Repeaters

Definition: Extend-A-Cell repeaters were a cost-effective, high-performing repeater solution for the first generation of cellular networks. They received signals from a cellular base station, filtered, amplified and then re-transmitted the signals to mobiles, thereby extending the coverage area of the base stations while providing means to overcome self-interference, allowing higher gain and higher power operation.

Year of the Innovation: 1987

What is the innovation that CommScope or one of its acquired companies was first in creating?

The innovation branded Extend-A-Cell is a frequency translating repeater developed in 1987 by Antenna Specialists, a company that ultimately became part of CommScope. Extend-A-Cell repeaters enabled mobile operators to extend the coverage area of a base station at a much lower cost than adding a new cell site with a base station. Initially, cell extension was accomplished by using on-frequency repeaters, which received signals from a base station and passed the signal directly to coverage antennas at the same frequency. On-frequency amplification and re-radiation can cause self-interference at insufficient antenna isolation, significantly reducing the effectiveness of the site’s transmitting capabilities. Extend-A-Cell repeaters solved the problem of donor-to-coverage antenna self-interference by translating the frequency of the RF signal received from the donor base station to a different frequency before transmitting the signal on the coverage antenna. To enable this method to work, the Extend-A-Cell repeater modified the control signals between the base station and the mobile.

What was happening in the market that this innovation was needed?

This innovation came about during the first generation of cellular networks when operators wanted to add more coverage as demand for cellular service increased. Cellular base stations were very expensive, costing around a quarter of a million dollars. Repeaters were a cost-effective way of extending coverage, but they had a problem with self-interference which limited the gain and power they could operate at, and this limited how far they were able to extend the range of the base station with a repeater.

Extend-A-Cell repeaters solved the self-interference problem. The Extend-A-Cell used directional donor antennas that pointed back to the donor base station and translated the donor antenna signal for retransmission to the coverage area. It received a signal from the base station, filtered it, translated it to a different channel, amplified it, and retransmitted the signal to the mobiles in the repeater coverage zone avoiding self-interference. Since the frequency of the input and output signals were different, filters in the Extend-A-Cell could prevent self-interference, and enable the Extend-A-Cell to reliably operate at the same power level as a base station.

How did this innovation benefit customers and the industry?

Extend-A-Cell enabled the rapid expansion of early cellular networks. It allowed cellular operators to expand the coverage area of their networks without the high expense and resource needs of base station installations by delivering high-gain, high-power repeaters that could have the same coverage area of a base station. This was enabled by the invention of techniques that significantly improved the isolation between donor and coverage antennas. This development allowed mobile operators to extend the range of a base station for much less cost, saving hundreds of millions of dollars across the industry.

Did this innovation act as the springboard for other innovations, and if so, how do they all tie together?

The original Extend-A-Cell was an analog AMPS (American Mobile Phone Service) product. Subsequent versions of the product added support for 2G digital cellular standards, provided digital signal processing, and led to developments in echo cancellation that further improved receive/transmit isolation. Extend-A-Cell developments ultimately lead to the development of Node repeaters in 2003.

What is the significance of the innovation for CommScope?

Extend-A-Cell and Node repeaters set the standard in the market for repeaters. Market success of this product led to further growth of the repeater and antenna design engineering and production facilities in Forest, Virginia. While there are other companies in the repeater market, CommScope is the market leader.

About the Author


Thomas Kummetz

Thomas Kummetz is vice president of research and development for the Distributed Coverage and Capacity Solutions (DCCS) segment of CommScope. Thomas joined CommScope through the acquisition of Andrew Corporation in 2007. Collectively, Thomas has served Andrew, Allen Telecom, and Mikom for over 21 years – leading R&D teams in the research and development of advanced Distributed Antenna Systems (DAS) and RF Repeaters. Thomas holds multiple patents in areas of DAS and RF Repeaters and leads the segment’s patent activities and IP portfolio management. Thomas has a Ph.D. in Electrical Engineering from Ulm University, a M.S.E.E and B.S.E.E. from the University of Braunschweig as well as a Certificate in Technology Leadership from the University of Virginia.


RF Repeater Systems