ITR: High Speed Internet Access in Buildings using Heating and Ventilation Ducts

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

0219278 Stancil High-speed internet access in buildings (residential, office, and commercial) is one of the most important challenges that next generation wireless networks face today. Further, modern buildings have complex communications infrastructures that may include provisions for building controls, alarms, wired and wireless telephones, high-speed data services, and wireless LANs. At present, these services are provided with separate wired/wireless systems for each service. An alternative approach to providing the communications infrastructure in buildings is to recognize that every building is already equipped with a microwave distribution system: the heating and ventilation (HVAC) ducts. These ducts are designed to carry air to and from all parts of the building, but can also function as hollow metal waveguides for microwave signals. Combining the HVAC with communications to form a single integrated system could lead to a new paradigm in smart building infrastructure. If widely adopted, the impact of this research could be very far-reaching, potentially impacting the design and construction of every major new building constructed throughout the developed world. For the most common duct sizes and communication frequencies, the ducts behave as multimode waveguides. The possibility of using multimode waveguides for microwave communications was first suggested more than 50 years ago, although the detailed channel characteristics have not been fully investigated. The goals of this proposal are to gain an understanding of mode scattering and conversion at common duct components such as bends, tees, and wyes, and to investigate how the multimode nature of the channel can be used to increase the capacity of the channel. To investigate the mode conversion and scattering, a multiple-antenna structure will be constructed that is capable of exciting specific modes or combinations of modes. The mode content upon passing through a component under study will be determined by scanning the near-field mode profile at the open exit end of the duct. The possibility of increasing the capacity of the duct will be investigated by constructing a pair of multiple antenna arrays for use as input and output and output couplers. Multiple-input/multiple-output multipath channel techniques will be used to demonstrate realization of two independent channels in the same frequency band. Two graduate students will be fully supported by this research. The topic provides a novel context for mastering concepts in microwave measurements, wireless channel models, channel capacity, and network architecture. Undergraduates will also be involved in the research for project credit. The results from the research will be presented at major international wireless conferences, and detailed papers will be submitted to archival journals to further disseminate the results. These presentations and papers also offer significant opportunities for the graduate students to hone their presentation and writing skills. Finally, results from the research will be used as examples and case studies in the introductory graduate Wireless Communications course offered each year. This course typically enrolls 50-60 students.