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GCN : April 2014
WIRELESS NETWORKS have revolutionized mobile computing, but they have faced two major challenges, especially when deployed outdoors: providing coverage where needed and security. Some are now betting that an older technology that was first applied to radar can make secure wireless coverage in the field more ef- ficient, secure and, yes, more a ordable. That technology is beamsteering, which uses phased arrays of antennas to shape electromagnetic wave patterns to direct them toward a specified target. "Phased arrays in general have been around for more than 50 years," said Joe Car- ey, CEO of Fidelity Comtech, a wireless communications company based in Longmont, Colo. "They were developed initially in World War II, and they ve been used predomi- nantly for radar applications and in electronic warfare. What we re doing is we re taking that technology and commercializing it for wire- less data networks." Ironically, the growth of wireless communications is itself presenting additional challenges that beamsteer- ing --- and Fidelity Comtech s Phocus Array product --- has the potential to overcome. In wireless, the advent of smartphones "is causing more and more congestion of spectrum," said Carey. "Phocus Array allows us to contour the beam so that we get coverage where we need it without causing undue in- terference to adjacent cells. And we re also not subjected to undue interference from adjacent cells," he added. The 802.11b/g Phocus Array is an eight-element, circular, phased-array an- tenna capable of providing dynamic antenna patterns --- ranging from a 360-degree omnidirectional pattern to a longer-reaching 43-degree pattern. The pattern can be changed on the fly --- in fact, in under 100 microseconds --- to focus on particular cli- ents or to avoid interference. Currently, Carey said, the company s main market is shipping container yards at ports. "We see it having the most value outdoors, because in the outdoor en- vironment you have a really high cost of siting an instal- lation," he said. "Obviously putting a smart antenna in an access point or base sta- tion increases cost ... [but] in an outdoor area, the cost of siting a radio can often far exceed the cost of the radio itself. That s when it makes more sense to invest in a smart antenna." As the equipment is get- ting more accurate and less expensive, Carey said he sees potential for other markets. "We see this having a lot of applicability in real-time location services -- being able to track mobile users and, say, unmanned aerial vehicles," Carey said. What s needed to gain accuracy and lower costs? Apart from refining algo- rithms, the key ingredient in improving phased-array wireless, Carey said, is better semiconductors to run those algorithms on. "There s an awful lot of computation that goes into these systems," Carey said, noting that the company is currently using its third generation of calibration algorithms. Specifically, the smart antennas need to com- pensate for imperfections in the circuit cards of the equip- ment as well as for noise in the external environment. "Figuring out how to build these custom antenna pat- terns took us years," Carey added. "I was a bit na ve when I started this. One of the things we have struggled with and now we think we have nailed is the interaction between the antenna and the medium access control layer --- the interaction between the radio protocol and the way the antenna should be- have. It s really complicated. And most of the protocols were not written with the concept of the spherical antenna in mind." Fidelity Comtech is also working on a project with the Department of Defense to use the beamsteering ca- pabilities of phased arrays to develop an anti-jam antenna. "If the enemy is trying to jam you, you can put a null on the jammer," Carey said. "It s a special kind of beamsteer- ing. We can point the beam at the intended receiver and we can form a null simulta- neously on the jammer." A nulling system measures the amplitude and phase of a signal and generates a counteracting signal that blocks the interference. The same technologies can potentially be used to reduce or eliminate unintentional interference. "Anyone who has deployed a large wireless data network will tell you that they often don t know when they are getting accidental jamming or intentional jamming," Carey said. "They just know that their network is not working and they have no idea why. We help them with that." • WWII RADAR TECH RE-ENLISTS AS A SMART ANTENNA TO TAME SPECTRUM CONGESTION BY PATRICK MARSHALL EMERGING TECH 34 GCN APRIL 2014 • GCN.COM "Anyone who has deployed a large wireless data network will tell you that they often don't know when they are getting accidental jamming or intentional jamming." JOE CAREY, FIDELITY COMTECH