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Applied Math Seminar
Wireless communications: Opportunities for time-reversal
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As user densities increase and users' data rate requirements become more demanding, challenging problems arise in the design of future communication systems. The bottleneck to the marketability of several promising techniques has been the high cost of the user equipment. These considerations give rise to a new paradigm in the design of wireless systems: the objective is to design a system that has advanced base stations, but simple and inexpensive user devices. The service providers can be convinced to transition into such a system model and recover the high infrastructure costs if more revenue-generating users can be accommodated per unit area. Time reversal (TR) is a powerful technique to achieve temporal and spatial focusing of the transmitted signal, as has been demonstrated in ultrasound and underwater communication experiments, and can therefore achieve our design objectives of device simplicity, high data rates and high user density. The parameters that affect the performance of TR are the available bandwidth, the nature of the propagation channel and the number of transducers. These parameters present several challenges in the context of wireless applications: spectrum is an expensive commodity, the radio channel has directional characteristics and varies with time, and wireless devices have hardware limitations. Nonetheless, the specifics of the wireless channel also present an under-explored opportunity with huge potential. In this talk, we investigate the impact of the application of TR to wireless communications, suggest possible applications and discuss the challenges and opportunities involved. |