An information-theoretic study of problems in wireless relaying
- Wireless relaying (using additional radio devices to improve the communication between a source and a destination) is poised to emerge as a key component in heterogeneous networks, internet of things and device-to-device communication. As a result, it is crucial to construct relaying models that capture practical constraints, derive fundamental limits on the performance in these models, and construct schemes that approach these performance limits. This thesis will describe our work in four specific instances in this direction. The first two chapters focus on questions that arise while operating a network of multiple relays. In the first of these, we take a closer look at the popular relaying paradigm of ``compress-forward'', wherein relays simply attempt to describe their received signals to the destination. We show that this paradigm can be optimized to deliver significantly better performance than what is suggested in existing results. The improvement is based on the surprising notion that the relays should do a poor job of describing their observations. In the next chapter, we consider the problem of selecting a subset of relays that is small but nevertheless good in the sense that it supports high end-to-end rates. This is non-trivial due to the large search space and difficult-to-evaluate objective function. We exploit the structure of the network to develop an approximation algorithm based on simulated annealing. The algorithm performs exceptionally well in terms of both the runtime and the objective of the selected set of relays. The next two chapters focus on the single relay channel, and study the impact of practical constraints of relay such as half-duplexing and lack of complete channel state information. In the first, we consider the problem of operating a single relay that can at any time either act as a receiver or a transmitter, but not both (half-duplex). Studying this setup gives rise to highly interesting questions, such as when should the relay receive and when should it transmit, whether it can decide this as a function of dynamically available information or not, what this function should be, what information about the channel is available at the relay, and how should it process the received signal. We provide a comprehensive investigation into these questions. In the next chapter, we consider a relay which is assumed to be uninformed about the state of the channel. This captures the fact that it can be difficult for the relay to obtain timely information about the fading between source and destination. We address the inadequacy of existing schemes by developing a novel scheme "cooperative-bin-forward" that achieves the capacity. This scheme leverages the benefits of the two basic relaying paradigms of "decode-forward" and "compress-forward".
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Electrical Engineering.
|El Gamal, Abbas A
|El Gamal, Abbas A
|Statement of responsibility
|Submitted to the Department of Electrical Engineering.
|Thesis (Ph.D.)--Stanford University, 2016.
- © 2016 by Ritesh Yadao Kolte
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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