Showing papers on "Physical layer published in 2013"
15 Nov 2013
TL;DR: This book is an ideal reference for postgraduate students, researchers, and engineers that need to obtain a macro-level understanding of physical layer security and its role in future wireless communication systems.
Abstract: Physical layer security has recently become an emerging technique to complement and significantly improve the communication security of wireless networks. Compared to cryptographic approaches, physical layer security is a fundamentally different paradigm where secrecy is achieved by exploiting the physical layer properties of the communication system, such as thermal noise, interference, and the time-varying nature of fading channels.Written by pioneering researchers, Physical Layer Security in Wireless Communications supplies a systematic overview of the basic concepts, recent advancements, and open issues in providing communication security at the physical layer. It introduces the key concepts, design issues, and solutions to physical layer security in single-user and multi-user communication systems, as well as large-scale wireless networks.The book starts with a brief introduction to physical layer security. The rest of the book is organized into four parts based on the different approaches used for the design and analysis of physical layer security techniques: Information Theoretic Approaches: introduces capacity-achieving methods and coding schemes for secure communication, as well as secret key generation and agreement over wireless channels Signal Processing Approaches: covers recent progress in applying signal processing techniques to design physical layer security enhancements Game Theoretic Approaches: discusses the applications of game theory to analyze and design wireless networks with physical layer security considerations Graph Theoretic Approaches: presents the use of tools from graph theory and stochastic geometry to analyze and design large-scale wireless networks with physical layer security constraints Presenting high-level discussions along with specific examples, illustrations, and references to conference and journal articles, this is an ideal reference for postgraduate students, researchers, and engineers that need to obtain a macro-level understanding of physical layer security and its role in future wireless communication systems.
289 citations
Patent•
28 Feb 2013TL;DR: In this paper, a method and apparatus may provide multi-user parallel channel access (MU-PCA) and/or single-user SU-PCAs using transmit and receive with symmetrical bandwidth, in the downlink (DL), uplink (UL), or combined DL and UL.
Abstract: A method and apparatus may provide multi-user parallel channel access (MU-PCA) and/or single-user parallel channel access (SU-PCA) using transmit and/or receive with symmetrical bandwidth, in the downlink (DL), uplink (UL), or combined DL and UL. SU-PCA and MU-PCA may support unequal modulation and coding schemes (MCS) and unequal transmit power. Medium access control (MAC) layer, Physical layer (PHY), and mixed and PHY layer methods and procedures may support UL, DL and combined UL and DL SU-PCA and MU-PCA using transmit and/or receive with symmetrical bandwidth. MU-PCA and/or SU-PCA may also be supported by MAC and PHY layer designs and procedures for downlink, uplink and combined uplink and downlink using transmit/receive with asymmetrical bandwidth.
288 citations
4 Mar 2013
TL;DR: This chapter contains sections titled: Introduction Communication Architecture Basics of Underwater Communications Physical Layer Medium Access Control Layer Network Layer Cross-Layer Design Experimental Platforms UW-Buffalo: An Underwater Acoustic Testbed at the University at Buffalo.
Abstract: This chapter contains sections titled: Introduction Communication Architecture Basics of Underwater Communications Physical Layer Medium Access Control Layer Network Layer Cross-Layer Design Experimental Platforms UW-Buffalo: An Underwater Acoustic Testbed at the University at Buffalo Conclusions References
259 citations
12 Aug 2013
TL;DR: This work presents a complete Orthogonal Frequency Division Multiplexing (OFDM) receiver implemented in GNU Radio and fitted for operation with an Ettus USRP N210, the first prototype of a GNU Radio based OFDM receiver for this technology.
Abstract: Experimental research on wireless communication protocols frequently requires full access to all protocol layers, down to and including the physical layer. Software Defined Radio (SDR) hardware platforms, together with real-time signal processing frameworks, offer a basis to implement transceivers that can allow such experimentation and sophisticated measurements. We present a complete Orthogonal Frequency Division Multiplexing (OFDM) receiver implemented in GNU Radio and fitted for operation with an Ettus USRP N210. To the best of our knowledge, this is the first prototype of a GNU Radio based OFDM receiver for this technology. Our receiver comprises all layers up to parsing the MAC header and extracting the payload of IEEE 802.11a/g/p networks. It supports both WiFi with a bandwidth of 20 MHz and IEEE 802.11p DSRC with a bandwidth of 10 MHz. We validated and verified our implementation by means of interoperability tests, and present representative performance measurements. By making the code available as Open Source we provide an easy-to-access system that can be readily used for experimenting with novel signal processing algorithms.
205 citations
TL;DR: This article gives an overview on several existing security attacks to the physical layer in cognitive radio networks and discusses the related countermeasures on how to defend against these attacks.
Abstract: In this article we explore the security issues on physical layer for cognitive radio networks. First we give an overview on several existing security attacks to the physical layer in cognitive radio networks. We then discuss the related countermeasures on how to defend against these attacks. We further investigate one of the most important physical layer security parameters, the secrecy capacity of a cognitive radio network, and study the outage probability of secrecy capacity of a primary user from a theoretical point of view. Furthermore, we present performance results for secrecy capacity and outage probability between a node and its neighbors. Our work summarizes the current advances of the physical layer security and brings insights on physical layer security analysis in cognitive radio networks.
190 citations
26 Jul 2013
TL;DR: This paper gives a technical overview of 802.11ah Physical (PHY) layer and Medium Access Control (MAC) layer, and evaluates the transmission range for indoor and outdoor environments and the theoretical throughput with newly defined channel access mechanisms.
Abstract: IEEE 802.11ah is an emerging Wireless LAN (WLAN) standard that defines a WLAN system operating at sub 1 GHz license-exempt bands. Thanks to the favorable propagation characteristics of the low frequency spectra, 802.11ah can provide much improved transmission range compared with the conventional 802.11 WLANs operating at 2.4 GHz and 5 GHz bands. 802.11ah can be used for various purposes including large scale sensor networks, extended range hotspot, and outdoor Wi-Fi for cellular traffic offloading, whereas the available bandwidth is relatively narrow. In this paper, we give a technical overview of 802.11ah Physical (PHY) layer and Medium Access Control (MAC) layer. For the 802.11ah PHY, which is designed based on the down-clocked operation of IEEE 802.11ac’s PHY layer, we describe its channelization and transmission modes. Besides, 802.11ah MAC layer has adopted some enhancements to fulfill the expected system requirements.These enhancements include the improvement of power saving features, support of large number of stations, efficient medium access mechanisms and throughput enhancements by greater compactness of various frame formats. Through the numerical analysis, we evaluate the transmission range for indoor and outdoor environments and the theoretical throughput with newly defined channel access mechanisms.
185 citations
TL;DR: In this article, the authors investigated two coordinated beamforming designs: the QoS beamforming and the max-min SINR (signal-to-interference-plus-noise ratio) beamforming.
Abstract: We study physical layer multicasting in multicell networks where each base station, equipped with multiple antennas, transmits a common message using a single beamformer to multiple users in the same cell. We investigate two coordinated beamforming designs: the quality-of-service (QoS) beamforming and the max-min SINR (signal-to-interference-plus-noise ratio) beamforming. The goal of the QoS beamforming is to minimize the total power consumption while guaranteeing that received SINR at each user is above a predetermined threshold. We present a necessary condition for the optimization problem to be feasible. Then, based on the decomposition theory, we propose a novel decentralized algorithm to implement the coordinated beamforming with limited information sharing among different base stations. The algorithm is guaranteed to converge and in most cases it converges to the optimal solution. The max-min SINR (MMS) beamforming is to maximize the minimum received SINR among all users under per-base station power constraints. We show that the MMS problem and a weighted peak-power minimization (WPPM) problem are inverse problems. Based on this inversion relationship, we then propose an efficient algorithm to solve the MMS problem in an approximate manner. Simulation results demonstrate significant advantages of the proposed multicast beamforming algorithms over conventional multicasting schemes.
169 citations
TL;DR: For the first time, a lightweight body area network authentication scheme BANA is proposed, which does not depend on prior-trust among nodes and can be efficiently realized on commercial off-the-shelf low-end sensors.
Abstract: In wireless body area network (BAN), node authentication is essential for trustworthy and reliable gathering of patient's critical health information. Traditional authentication solutions depend on prior trust among nodes whose establishment would require either key pre-distribution or non-intuitive participation by inexperienced users. Most existing non-cryptographic authentication schemes require advanced hardware or significant modifications to the system software, which are impractical for BANs. In this paper, for the first time, we propose a lightweight body area network authentication scheme BANA. Different from previous work, BANA does not depend on prior-trust among nodes and can be efficiently realized on commercial off-the-shelf low-end sensors. We achieve this by exploiting a unique physical layer characteristic naturally arising from the multi-path environment surrounding a BAN, i.e., the distinct received signal strength (RSS) variation behaviors among on-body channels and between on-body and off-body communication channels. Based on distinct RSS variations, BANA adopts clustering analysis to differentiate the signals from an attacker and a legitimate node. We also make use of multi-hop on-body channel characteristics to enhance the robustness of our authentication mechanism. The effectiveness of BANA is validated through extensive real-world experiments under various scenarios. It is shown that BANA can accurately identify multiple attackers with minimal amount of overhead.
152 citations
29 Mar 2013
TL;DR: This book introduces the theoretical elements at the basis of various classes of algorithms commonly employed in the physical layer (and, in part, in MAC layer) of wireless communications systems.
Abstract: This book introduces the theoretical elements at the basis of various classes of algorithms commonly employed in the physical layer (and, in part, in MAC layer) of wireless communications systems. It focuses on single user systems, so ignoring multiple access techniques. Moreover, emphasis is put on single-input single-output (SISO) systems, although some relevant topics about multiple-input multiple-output (MIMO) systems are also illustrated.Comprehensive wireless specific guide to algorithmic techniquesProvides a detailed analysis of channel equalization and channel coding for wireless applicationsUnique conceptual approach focusing in single user systemsCovers algebraic decoding, modulation techniques, channel coding and channel equalisation
143 citations
Patent•
23 Aug 2013TL;DR: In this article, the physical layer resources to a plurality of medium access control (MAC) instances that are associated with different serving sites that are independently scheduled are disclosed. But, the authors do not discuss how to prevent conflicts between transmissions from the first MAC instance and transmission requests from the second MAC instance.
Abstract: Methods and systems are disclosed for providing physical layer resources to a plurality of medium access control (MAC) instances that are associated with different serving sites that are independently scheduled. For example, a WTRU may utilize a first physical layer configuration for transmitting to a first serving site associated with a first MAC instance. The WTRU may utilize a second physical layer configuration for transmitting to a second serving site associated with a second MAC instance. The WTRU may prevent conflicts between transmission requests from the first MAC instance and transmission requests from the second MAC instance. For example, preventing the conflicts may include utilizing one or more of time segregation or frequency segregation for transmissions associated with the first MAC instance and transmissions associated with the second MAC instance.
125 citations
TL;DR: This paper proposes a novel PHYsical layer Challenge-Response Authentication Mechanism (PHY-CRAM) for wireless networks that achieves both high successful authentication rate and low false acceptance rate in various channel conditions and under various attacks.
Abstract: Exploiting the unique properties of the physical layer to enhance or complement authentication strength in wireless networks has attracted a lot of research attention recently. In this paper, we propose a novel PHYsical layer Challenge-Response Authentication Mechanism (PHY-CRAM) for wireless networks. PHY-CRAM is suitable for both one-way and mutual authentication. It fully utilizes the randomness, reciprocal, and location decorrelation features of the wireless fading channel, and is immune to various passive and active attacks. In the authentication procedure, challenge-response signals are exchanged at the physical layer, which allow two devices to verify their shared secrets while not revealing these secrets to attackers. PHY-CRAM adopts orthogonal frequency-division multiplexing (OFDM) technique which separately modulates the higher layer information and shared keys on subcarriers' phases and amplitudes respectively, in order to prevent channel probing from traffic-related information. We conduct extensive simulation study and develop a prototype using field-programmable gate array (FPGA) and discrete radio frequency (RF) components to evaluate PHY-CRAM in real-world environments. It shows that PHY-CRAM achieves both high successful authentication rate and low false acceptance rate in various channel conditions and under various attacks.
7 Apr 2013
TL;DR: MonoPHY leverages the physical layer information of WiFi networks supported by the IEEE 802.11n standard to provide accurate DF localization with only one stream and leverages both the low-level Channel State Information and the MIMO information to capture the human effect on signal strength.
Abstract: Device-free (DF) indoor localization has grasped great attention recently as a value-added service to the already installed WiFi infrastructure as it allows the tracking of entities that do not carry any devices nor participate actively in the localization process. Current approaches, however, require a relatively large number of wireless streams, i.e. transmitter-receiver pairs, which is not available in many typical scenarios, such as home monitoring. In this paper, we introduce MonoPHY as an accurate mono-stream device-free WLAN localization system. MonoPHY leverages the physical layer information of WiFi networks supported by the IEEE 802.11n standard to provide accurate DF localization with only one stream. In particular, MonoPHY leverages both the low-level Channel State Information and the MIMO information to capture the human effect on signal strength. Experimental evaluation in a typical apartment, with a side-by-side comparison with the state-of-the-art, shows that MonoPHY can achieve an accuracy of 1.36m. This corresponds to at least 48% enhancement in median distance error over the state-of-the-art DF localization systems using a single stream only.
TL;DR: Not only the secure communication but also the MIMO gain can be guaranteed by using the proposed schemes, including the precoding matrix index (PMI)-based secret key generation with rotation matrix (MOPRO) and the channel quantization-based (MOCHA) scheme.
Abstract: In physical-layer security, secret bits are extracted from wireless channels. With the assumption of channel reciprocity, the legitimate users share the same channel which is independent of the channels between the legitimate users and the eavesdropper, leading to secure transmissions. However, practical implementation of the physical layer security faces many challenges. First, for the correlated channel such as the multiple-input and multiple-output (MIMO) channel, the security is decreased due to the correlation between the generated secret bits. Second, the nearby eavesdropper posts a security threat due to observing the same channel as the legitimate user's. Third, the eavesdroppers might try to reconstruct the wireless environments. In this paper, we propose two practical physical layer security schemes for the MIMO orthogonal frequency-division multiplexing (MIMO-OFDM) systems: the precoding matrix index (PMI)-based secret key generation with rotation matrix (MOPRO) and the channel quantization-based (MOCHA) scheme. The former utilizes PMI and rotated reference signals to prevent the eavesdroppers from learning the secret key information and the latter applies channel quantization in order to extract more secret key bits. It is shown that not only the secure communication but also the MIMO gain can be guaranteed by using the proposed schemes.
TL;DR: This letter considers a multi-antenna downlink network where a secure user (SU) coexists with a passive eavesdropper, and combines the physical layer security technique based on switched beam beamforming with an energy-efficient power allocation scheme.
Abstract: In this letter, we consider a multi-antenna downlink network where a secure user (SU) coexists with a passive eavesdropper. There are two design requirements for such a network. First, the information should be transferred in a secret and efficient manner. Second, the quality of service (QoS), i.e. delay sensitivity, should be take into consideration to satisfy the demands of real-time wireless services. In order to fulfill the two requirements, we combine the physical layer security technique based on switched beam beamforming with an energy-efficient power allocation. The problem is formulated as the maximization of the secrecy energy efficiency subject to delay and power constraints. By solving the optimization problem, we derive an energy-efficient power allocation scheme. Numerical results validate the effectiveness of the proposed scheme.
Book•
21 Apr 2013
TL;DR: The work extensively addresses challenges of link adaptation, adaptive resource allocation and interference mitigation in such systems, and the domain of cross-layer design, i.e. the combination of physical layer aspects and issues of higher layers, are considered in detail.
Abstract: (Preliminary): The Orthogonal Frequency Division Multiplexing (OFDM) digital transmission technique has several advantages in broadcast and mobile communications applications The main objective of this book is to give a good insight into these efforts, and provide the reader with a comprehensive overview of the scientific progress which was achieved in the last decade Besides topics of the physical layer, such as coding, modulation and non-linearities, a special emphasis is put on system aspects and concepts, in particular regarding cellular networks and using multiple antenna techniques The work extensively addresses challenges of link adaptation, adaptive resource allocation and interference mitigation in such systems Moreover, the domain of cross-layer design, ie the combination of physical layer aspects and issues of higher layers, are considered in detail These results will facilitate and stimulate further innovation and development in the design of modern communication systems, based on the powerful OFDM transmission technique
Posted Content•
TL;DR: The results indicate that the proposed optimized FiWi routing algorithm (OFRA) outperforms minimum (wireless) hop and delay routing in terms of throughput for balanced and unbalanced traffic loads, at the expense of a slightly increased mean delay at small to medium traffic loads.
Abstract: Current Gigabit-class passive optical networks (PONs) evolve into next-generation PONs, whereby high-speed 10+ Gb/s time division multiplexing (TDM) and long-reach wavelength-broadcasting/routing wavelength division multiplexing (WDM) PONs are promising near-term candidates. On the other hand, next-generation wireless local area networks (WLANs) based on frame aggregation techniques will leverage physical layer enhancements, giving rise to Gigabit-class very high throughput (VHT) WLANs. In this paper, we develop an analytical framework for evaluating the capacity and delay performance of a wide range of routing algorithms in converged fiber-wireless (FiWi) broadband access networks based on different next-generation PONs and a Gigabit-class multi-radio multi-channel WLAN-mesh front-end. Our framework is very flexible and incorporates arbitrary frame size distributions, traffic matrices, optical/wireless propagation delays, data rates, and fiber faults. We verify the accuracy of our probabilistic analysis by means of simulation for the wireless and wireless-optical-wireless operation modes of various FiWi network architectures under peer-to-peer, upstream, uniform, and nonuniform traffic scenarios. The results indicate that our proposed optimized FiWi routing algorithm (OFRA) outperforms minimum (wireless) hop and delay routing in terms of throughput for balanced and unbalanced traffic loads, at the expense of a slightly increased mean delay at small to medium traffic loads.
Posted Content•
TL;DR: In this article, the authors considered a multi-antenna downlink network where a secure user (SU) coexists with a passive eavesdropper and formulated the problem as the maximization of the secrecy energy efficiency subject to delay and power constraints.
Abstract: In this letter, we consider a multi-antenna downlink network where a secure user (SU) coexists with a passive eavesdropper. There are two design requirements for such a network. First, the information should be transferred in a secret and efficient manner. Second, the quality of service (QoS), i.e. delay sensitivity, should be take into consideration to satisfy the demands of real-time wireless services. In order to fulfill the two requirements, we combine the physical layer security technique based on switched beam beamforming with an energy-efficient power allocation. The problem is formulated as the maximization of the secrecy energy efficiency subject to delay and power constraints. By solving the optimization problem, we derive an energy-efficient power allocation scheme. Numerical results validate the effectiveness of the proposed scheme.
TL;DR: This paper designs secure on-off transmission schemes to maximize the throughput subject to a constraint on secrecy outage probability and shows how the optimal on- off transmission thresholds and the achievable throughput vary with the amount of knowledge on the eavesdropper's channel.
Abstract: Physical layer security has recently been regarded as an emerging technique to complement and improve the communication security in future wireless networks. The current research and development in physical layer security are often based on the ideal assumption of perfect channel knowledge or the capability of variable-rate transmissions. In this paper, we study the secure transmission design in more practical scenarios by considering channel estimation errors at the receiver and investigating both fixed-rate and variable-rate transmissions. Assuming quasi-static fading channels, we design secure on-off transmission schemes to maximize the throughput subject to a constraint on secrecy outage probability. For systems with given and fixed encoding rates, we show how the optimal on-off transmission thresholds and the achievable throughput vary with the amount of knowledge on the eavesdropper's channel. In particular, our design covers the interesting case where the eavesdropper also uses the pilots sent from the transmitter to obtain imperfect channel estimation. An interesting observation is that using too much pilot power can harm the throughput of secure transmission if both the legitimate receiver and the eavesdropper have channel estimation errors, while the secure transmission always benefits from increasing pilot power when only the legitimate receiver has channel estimation errors but not the eavesdropper. When the encoding rates are controllable parameters to design, we further derive both a non-adaptive and an adaptive rate transmission schemes by jointly optimizing the encoding rates and the on-off transmission thresholds to maximize the throughput of secure transmissions.
TL;DR: This paper makes an exhaustive review of the monitoring techniques and systems for TDM-PON, mostly proposed within the last five years, and makes a detailed classification of all these approaches and qualitatively compare characteristics in a list of performance parameters and aspects.
Abstract: In order to enable new services that require high data rates over longer distances, the optical fiber substitutes the copper cable step by step in the access network area. Time division multiplexed - Passive optical network (TDM-PON) is a fast emerging architecture that uses only passive components between the customer and the central office. PON operators need a monitoring system for the physical layer to guarantee high service quality. This monitoring system is necessary during the fiber installation, final network installation testing, regular operation of the network, and for fault localization. First, in this paper, we present the motivations, requirements and challenges of TDM-PON monitoring. Second, we make an exhaustive review of the monitoring techniques and systems for TDM-PON, mostly proposed within the last five years. In our survey we include the approaches already available in the market even with limited performance and those still in research. Third, we make a detailed classification of all these approaches and qualitatively compare characteristics in a list of performance parameters and aspects. Finally, we outline open issues and future research perspectives in physical layer PON monitoring that may target higher performance, lower cost, or scalability to next generation PON architectures. This includes wavelength division multiplexing (WDM), TDM over WDM or long-reach PONs intended to extend the reach from 20 up to 100 km distances and beyond.
Patent•
IBM1
TL;DR: In this article, an approach is provided in which a first virtual machine, executing on a host computer system, generates a data packet with a target destination at a second virtual machine over a computer network.
Abstract: An approach is provided in which a first virtual machine, executing on a host computer system, generates a data packet with a target destination at a second virtual machine over a computer network. The host computer system identifies a data flow corresponding to the data packet based the data packet's header information, and analyzes path weightings of available paths that are made available to the identified data flow. In turn, the host computer system assigns one of the available paths to the identified data flow corresponding to a pre-defined physical layer path from the first virtual machine to the second virtual machine.
Book•
27 Jul 2013TL;DR: An overview of network performance in cooperative wireless networks is presented to study how the performance gain of cooperative diversity at the physical layer can be reflected at the networking layer, thus ultimately improving application performance.
Abstract: Cooperative communication has been shown as an effective way to exploit spatial diversity to improve the quality of wireless links. The key feature of cooperative transmission is to encourage single-antenna devices to share their antennas cooperatively such that a virtual and distributed antenna array can be constructed, and, as a result, reception reliability can be improved and power consumption can be reduced significantly. With better understanding of such a physical layer technique, it becomes critically important to study how the performance gain of cooperative diversity at the physical layer can be reflected at the networking layer, thus ultimately improving application performance. This article presents an overview of network performance in cooperative wireless networks.
TL;DR: A method for generating and sharing a secret key using phase fluctuations in fiber optical links, similar to the classical asymmetric algorithms (Diffie-Hellman, RSA, etc.).
Abstract: We propose and experimentally demonstrate a method for generating and sharing a secret key using phase fluctuations in fiber optical links. The obtained key can be readily used to support secure communication between the parties. The security of our approach is based on a fundamental asymmetry associated with the optical physical layer: the sophistication of tools needed by an eavesdropping adversary to subvert the key establishment is significantly greater and more costly than the complexity needed by the legitimate parties to implement the scheme. In this sense, the method is similar to the classical asymmetric algorithms (Diffie-Hellman, RSA, etc.).
Patent•
15 Mar 2013TL;DR: In this paper, a periodic control window is embedded in a link layer data stream to be sent over a serial data link, where the control window provides physical layer information including information for use in initiating state transitions on the data link.
Abstract: A periodic control window is embedded in a link layer data stream to be sent over a serial data link, where the control window is configured to provide physical layer information including information for use in initiating state transitions on the data link. The link layer data can be sent during a link transmitting state of the data link and the control window can interrupt the sending of flits. In one aspect, the information includes link width transition data indicating an attempt to change the number of active lanes on the link.
TL;DR: This paper proposes a new concept called "reality check” and presents a method of using a protocol model with reality check for wireless networks and shows that by appropriate setting of the interference range in the protocol model, it is possible to narrow the solution gap between the two models.
Abstract: This paper tries to reconcile the tension between the physical model and the protocol model that have been used to characterize interference relationship in a multihop wireless network. The physical model (a.k.a. signal-to-interference-and-noise ratio model) is widely considered as a reference model for physical layer behavior but its application in multihop wireless networks is limited by its complexity. On the other hand, the protocol model (a.k.a. disk graph model) is simple but there have been doubts on its validity. This paper explores the following fundamental question: How to correctly use the protocol interference model? We show that, in general, solutions obtained under the protocol model may be infeasible and, thus, results based on blind use of protocol model can be misleading. We propose a new concept called "reality check” and present a method of using a protocol model with reality check for wireless networks. Subsequently, we show that by appropriate setting of the interference range in the protocol model, it is possible to narrow the solution gap between the two models. Our simulation results confirm that this gap is indeed small (or even negligible). Thus, our methodology of joint reality check and interference range setting retains the protocol model as a viable approach to analyze multihop wireless networks.
Proceedings Article•
3 Jul 2013TL;DR: An overview of the main challenges that must be tackled to perform a joint design of the backhaul and radio access network in a cloud-based mobile network and proposes the use of cooperative routing schemes that optimize the cell load distribution and admission and congestion control algorithms that use access and backhaul information.
Abstract: In this work, we give an overview of the main challenges that must be tackled to perform a joint design of the backhaul and radio access network in a cloud-based mobile network. The deployment of a very dense network based on small cells connected through a heterogeneous backhaul is a realistic way of achieving a high throughput in a mobile network. But, the non-ideal characteristics of this backhaul and the blurring borders between access and the backhaul networks require a joint design of both, involving the three lower OSI layers. In the physical layer, we consider to use adaptable techniques including In-Network-Processing (INP) and Multi-Point Turbo Detection, as well as Coordinated Beamforming and Joint Network-Channel Coding. Regarding the MAC layer, we pay special attention to partly distributed algorithms operating on smaller time-scales that take into account backhaul constraints and inter-cell interference. Finally, in the network layer we propose the use of cooperative routing schemes that optimize the cell load distribution and admission and congestion control algorithms that use access and backhaul information. Based on these approaches, a joint design of access and backhaul network can be effectively carried out, in order to enable the deployment of small-cells and heterogeneous backhaul.
Book•
30 Sep 2013
TL;DR: This book introduces various signal processing approaches to enhance physical layer secrecy in multi-antenna wireless systems and focuses specifically on the signal processing aspects, including beamforming and precoding techniques for data transmission and discriminatory training schemes for channel estimation.
Abstract: This book introduces various signal processing approaches to enhance physical layer secrecy in multi-antenna wireless systems. Wireless physical layer secrecy has attracted much attention in recent years due to the broadcast nature of the wireless medium and its inherent vulnerability to eavesdropping. While most articles on physical layer secrecy focus on the information-theoretic aspect, we focus specifically on the signal processing aspects, including beamforming and precoding techniques for data transmission and discriminatory training schemes for channel estimation. The discussions will cover cases with collocated and with distributed antennas, i.e., relays. The topics covered will be of interest to researchers in the signal processing community as well to practitioners and engineers working in this area. This book will also review recent works that apply these signal processing approaches to more advanced wireless systems, such as OFDM systems, multicell systems, cognitive radio, multihop networks etc. This will draw interest from researchers that wish to pursue the topic further in these new directions. This book is divided into three parts: (i) data transmission, (ii) channel estimation and (iii) advanced applications. Even though many works exist in the literature on these topics, the approaches and perspectives taken were largely diverse. This book provides a more organized and systematic view of these designs and to lay a solid foundation for future work in these areas. Moreover, by presenting the work from a signal processing perspective, this book will also trigger more research interest from the signal processing community and further advance the field of physical layer secrecy along the described directions. This book allows readers to gain basic understanding of works on physical layer secrecy, knowledge of how signal processing techniques can be applied to this area, and the application of these techniques in advanced wireless applications.
TL;DR: The proposed novel message authentication schemes for the smart meter system yield the lower time delay for authenticating each message, which can satisfy the requirement of the real-time control over the smart grid.
Abstract: The study introduces the novel message authentication schemes for the smart meter system, where the symmetric cryptography-based physical layer-assisted message authentication (PLAA) scheme and the public key infrastructure- based PLAA scheme are introduced. The proposed schemes integrate the conventional message authentication schemes and the physical layer authentication mechanisms by taking advantage of temporal and spatial uniqueness in physical layer channel responses, aiming to achieve fast authentication while minimising the packet transmission overhead. The authors also verify their claims through extensive analysis and simulation via comparing with proposed PLAA scheme with traditional upper layer authentication schemes. The proposed novel schemes yield the lower time delay for authenticating each message, which can satisfy the requirement of the real-time control over the smart grid.
Patent•
22 Oct 2013TL;DR: In this article, a PHY is coupled to a serial, differential link that is to include a number of lanes, and the PHY periodically issues a blocking link state (BLS) request to cause an agent to enter a BLS to hold off link layer flit transmission for a duration.
Abstract: A physical layer (PHY) is coupled to a serial, differential link that is to include a number of lanes. The PHY includes a transmitter and a receiver to be coupled to each lane of the number of lanes. The transmitter coupled to each lane is configured to embed a clock with data to be transmitted over the lane, and the PHY periodically issues a blocking link state (BLS) request to cause an agent to enter a BLS to hold off link layer flit transmission for a duration. The PHY utilizes the serial, differential link during the duration for a PHY associated task selected from a group including an in-band reset, an entry into low power state, and an entry into partial width state
1 Jul 2013
TL;DR: This work proposes an unconventional approach that leverages physical layer photonic technologies to build custom communication devices for accelerating each *-cast pattern, and integrates such devices into an application-driven, dynamically configurable photonics accelerated data center network.
Abstract: Not only do big data applications impose heavy bandwidth demands, they also have diverse communication patterns denoted as *-cast) that mix together unicast, multicast, incast, and all-to-all-cast. Effectively supporting such traffic demands remains an open problem in data center networking. We propose an unconventional approach that leverages physical layer photonic technologies to build custom communication devices for accelerating each *-cast pattern, and integrates such devices into an application-driven, dynamically configurable photonics accelerated data center network. We present preliminary results from a multicast case study to highlight the potential benefits of this approach.
TL;DR: The problem definition and the proposed algorithms are general and applicable to flex-grid as well as fixed-grid networks, and algorithms based on integer linear programming formulations for transparent and translucent networks (without or with regenerators) are presented.
Abstract: We consider the planning problem of a flexible optical network. Given the traffic matrix and the transponders' feasible configurations that account for the physical layer, we formulate the planning problem considering both the use or not of regenerators. Demands are served for their requested rates by choosing the route, selecting the transmission configuration, breaking the transmissions in more than one connection and placing regenerators, if needed, and allocating the spectrum to them. The objective is to serve the traffic and find a solution that is Pareto optimal with respect to the maximum spectrum used and the cost (number and type) of transponders used. The problem definition and the proposed algorithms are general and applicable to flex-grid as well as fixed-grid networks. We start by presenting algorithms based on integer linear programming formulations for transparent and translucent networks (without or with regenerators) and we continue by presenting heuristic algorithms. Using input driven by transmission studies on optical orthogonal frequency-division multiplexing (OFDM)-based networks we evaluate the performance gains that can be obtained by an OFDM over a mixed line rate fixed-grid WDM optical network.