Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey

This paper provides a comprehensive review of the domain of physical layer security in multiuser wireless networks. The essential premise of physical-layer security is to enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers without relying on higher-layer encryption. This can be achieved primarily in two ways: without the need for a secret key by intelligently designing transmit coding strategies, or by exploiting the wireless communication medium to develop secret keys over public channels. The survey begins with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security. We then describe the evolution of secure transmission strategies from point-to-point channels to multiple-antenna systems, followed by generalizations to multiuser broadcast, multiple-access, interference, and relay networks. Secret-key generation and establishment protocols based on physical layer mechanisms are subsequently covered. Approaches for secrecy based on channel coding design are then examined, along with a description of inter-disciplinary approaches based on game theory and stochastic geometry. The associated problem of physical-layer message authentication is also introduced briefly. The survey concludes with observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials, 201

Sparse Signal Processing Concepts for Efficient 5G System Design

As it becomes increasingly apparent that 4G will not be able to meet the emerging demands of future mobile communication systems, the question what could make up a 5G system, what are the crucial challenges and what are the key drivers is part of intensive, ongoing discussions. Partly due to the advent of compressive sensing, methods that can optimally exploit sparsity in signals have received tremendous attention in recent years. In this paper we will describe a variety of scenarios in which signal sparsity arises naturally in 5G wireless systems. Signal sparsity and the associated rich collection of tools and algorithms will thus be a viable source for innovation in 5G wireless system design. We will discribe applications of this sparse signal processing paradigm in MIMO random access, cloud radio access networks, compressive channel-source network coding, and embedded security. We will also emphasize important open problem that may arise in 5G system design, for which sparsity will potentially play a key role in their solution.Comment: 18 pages, 5 figures, accepted for publication in IEEE Acces

Doctor of Philosophy

dissertationCross layer system design represents a paradigm shift that breaks the traditional layer-boundaries in a network stack to enhance a wireless network in a number of di erent ways. Existing work has used the cross layer approach to optimize a wireless network in terms of packet scheduling, error correction, multimedia quality, power consumption, selection of modulation/coding and user experience, etc. We explore the use of new cross layer opportunities to achieve secrecy and e ciency of data transmission in wireless networks. In the rst part of this dissertation, we build secret key establishment methods for private communication between wireless devices using the spatio-temporal variations of symmetric-wireless channel measurements. We evaluate our methods on a variety of wireless devices, including laptops, telosB sensor nodes, and Android smartphones, with diverse wireless capabilities. We perform extensive measurements in real-world environments and show that our methods generate high entropy secret bits at a signi cantly faster rate in comparison to existing approaches. While the rst part of this dissertation focuses on achieving secrecy in wireless networks, the second part of this dissertation examines the use of special pulse shaping lters of the lterbank multicarrier (FBMC) physical layer in reliably transmitting data packets at a very high rate. We rst analyze the mutual interference power across subcarriers used by di erent transmitters. Next, to understand the impact of FBMC beyond the physical layer, we devise a distributed and adaptive medium access control protocol that coordinates data packet tra c among the di erent nodes in the network in a best e ort manner. Using extensive simulations, we show that FBMC consistently achieves an order-of-magnitude performance improvement over orthogonal frequency division multiplexing (OFDM) in several aspects, including packet transmission delays, channel access delays, and e ective data transmission rate available to each node in static indoor settings as well as in vehicular networks

Physical layer security for machine type communication networks

Abstract. We examine the physical layer security for machine type communication networks and highlight a secure communication scenario that consists of a transmitter Alice, which employs Transmit Antenna Selection, while a legitimate receiver Bob that uses Maximum Ratio Combining, as well as an eavesdropper Eve. We provide a solution to avoid eavesdropping and provide ways to quantify security and reliability. We obtain closed-form expressions for Multiple-Input Multiple-Output and Multi-antenna Eavesdropper (MIMOME) scenario. The closed{-}form expressions for three useful variations of MIMOME scenario, i.e., MISOME, MIMOSE, and MISOSE are also provided. A low cost and less complex system for utilizing the spatial diversity in multiple antennas system, while guaranteeing secrecy and reliability. Similarly, it is also assumed that Alice, Bob, and Eve can estimate their channel state information, and then we evaluate the performance of closed-form expressions in terms of secrecy outage probability and provide Monte Carlo simulations to corroborate the proposed analytical framework

Lists that are smaller than their parts: A coding approach to tunable secrecy

We present a new information-theoretic definition and associated results, based on list decoding in a source coding setting. We begin by presenting list-source codes, which naturally map a key length (entropy) to list size. We then show that such codes can be analyzed in the context of a novel information-theoretic metric, \epsilon-symbol secrecy, that encompasses both the one-time pad and traditional rate-based asymptotic metrics, but, like most cryptographic constructs, can be applied in non-asymptotic settings. We derive fundamental bounds for \epsilon-symbol secrecy and demonstrate how these bounds can be achieved with MDS codes when the source is uniformly distributed. We discuss applications and implementation issues of our codes.Comment: Allerton 2012, 8 page