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Multi-element antennas offer the possibility of increasing the spatial reuse of wireless spectrum by ??nulling?? out interfering signals. However, the interference suppression performance is highly sensitive to small errors in the gains applied to the antenna elements. In this paper, we examine in detail the effect of one specific source of error that arises from quantizing array weights. We show...
This paper presents a practical method for using multi-antenna radios to cancel interference in cognitive radio systems. Under this method, secondary radio transmitters use beamforming techniques to find antenna weights that place nulls at the primary receivers, and secondary radio receivers use adaptive techniques to decode in the presence of interference from primary users. As an example, we show...
This paper proposes a new framework for spectrum reuse. Existing architectures have centered on secondary users (cognitive radios) that can reliably sense primary users and opportunistically transmit, without directly interacting with the primary system. We present a paradigm in which the primary and secondary systems cooperate, to minimize interference to primary users and provide predictable access...
We consider a distributed beamforming problem where nodes are restricted to sending binary phases to a receiver that has access to a one-bit feedback channel. Our simplified model allows us to prove a rigorous lower bound on the running time and to explore algorithmic techniques and analyses. We demonstrate both upper and lower bounds on the convergence time that are linear in the number of nodes...
There is increased interest in networking arrays of sensors for distributed source localization. An analysis of the generalized model and estimation performance for multiple sources being observed by a field of networked arrays has recently been studied in via the Cramer-Rao lower bound (CRLB). In previous work concerning the CRB and multiple sources, the models were formulated for observations with...
Localization of acoustic sources has been an area of research starting primarily with underwater acoustics. Recently, localization of sources in air has become a topic of interest for automatic detection, surveillance and tracking for military applications. Other application include novel teleconference devices, specifically automatic focusing on the person currently speaking. Current technology relies...
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