Self interferometry : self interference cancellation and its applications
- Wireless radios are typically half-duplex radios, and hence, the current wireless networks are Time Division Duplex(TDD) or Frequency Division Duplex (FDD). Full-duplex for wireless communications is considered impossible i.e. radios cannot transmit and receive at the same frequency at the same time. If we could achieve full duplex radios we won't need TDD or FDD strategy, we could potentially double the spectral efficiency. The fundamental challenge in achieving full duplex radios, when a radio is transmitting while simultaneously trying to receive (hear another radio) on the same frequency, it cannot. It's own transmission acts as a very strong self-interference. In this dissertation, we present the design, prototype and implementation of full duplex mimo radios. In particular, we built the first single antenna per chain full-duplex MIMO radios for 2.4 GHz WiFi-PHY i.e. to achieve an m-chain MIMO transceiver we need only m antenna. We design novel cancellation algorithms and circuits that reduce all self-interference to the noise floor and enable full-duplex MIMO PHY with almost no loss. The cancellation algorithms designed for full duplex themselves are of independent interest and apply to many other interference problems in wireless. We exploit this to build a full duplex relay which is the first one to provide both range extension and increase the capacity, is oblivious to ongoing transmission the source and the destination don't even realise that relay exist. Further, we build on top of the cancellation BackFi; a system that provides high throughput connectivity using backscatter to IoT devices at a very lower power. BackFi backscatters all ubiquitous ongoing WiFi signals to provide connectivity. Thus, providing connectivity without using extra spectrum just leveraging full duplex link. The cancellation, in essence, cancels all the reflections from the environment of self transmitted signal, inferring the reflection from cancellation provides us information about the environment. Towards the end, we abstract this information with a platform of Self-Interferometry, which provides with a unique way of looking at environment using wireless signals instead of light. Thus building a camera with wireless radios.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Electrical Engineering.
|Prabhakar, Balaji, 1967-
|Prabhakar, Balaji, 1967-
|Statement of responsibility
|Submitted to the Department of Electrical Engineering.
|Thesis (Ph.D.)--Stanford University, 2016.
- © 2016 by Dinesh Bharadia
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