Showing papers on "Communications system published in 2013"

Ambient backscatter: wireless communication out of thin air

Abstract: We present the design of a communication system that enables two devices to communicate using ambient RF as the only source of power. Our approach leverages existing TV and cellular transmissions to eliminate the need for wires and batteries, thus enabling ubiquitous communication where devices can communicate among themselves at unprecedented scales and in locations that were previously inaccessible.To achieve this, we introduce ambient backscatter, a new communication primitive where devices communicate by backscattering ambient RF signals. Our design avoids the expensive process of generating radio waves; backscatter communication is orders of magnitude more power-efficient than traditional radio communication. Further, since it leverages the ambient RF signals that are already around us, it does not require a dedicated power infrastructure as in traditional backscatter communication. To show the feasibility of our design, we prototype ambient backscatter devices in hardware and achieve information rates of 1 kbps over distances of 2.5 feet and 1.5 feet, while operating outdoors and indoors respectively. We use our hardware prototype to implement proof-of-concepts for two previously infeasible ubiquitous communication applications.

Wireless sub-THz communication system with high data rate

Abstract: A wireless communication system with a maximum data rate of 100 Gbit s−1 over 20 m is demonstrated using a carrier frequency of 237.5 GHz. The photonic schemes used to generate the signal carrier and local oscillator are described, as is the fast photodetector used as a mixer for data extraction.

Beamspace MIMO for Millimeter-Wave Communications: System Architecture, Modeling, Analysis, and Measurements

Abstract: Millimeter-wave wireless systems are emerging as a promising technology for meeting the exploding capacity requirements of wireless communication networks. Besides large bandwidths, small wavelengths at mm-wave lead to a high-dimensional spatial signal space, that can be exploited for significant capacity gains through high-dimensional multiple-input multiple-output (MIMO) techniques. In conventional MIMO approaches, optimal performance requires prohibitively high transceiver complexity. By combining the concept of beamspace MIMO communication with a hybrid analog-digital transceiver, continuous aperture phased (CAP) MIMO achieves near-optimal performance with dramatically lower complexity. This paper presents a framework for physically-accurate computational modeling and analysis of CAP-MIMO, and reports measurement results on a DLA-based prototype for multimode line-of-sight communication. The model, based on a critically sampled system representation, is used to demonstrate the performance gains of CAP-MIMO over state-of-the-art designs at mm-wave. For example, a CAP-MIMO system can achieve a spectral efficiency of 10-20 bits/s/Hz with a 17-31 dB power advantage over state-of-the-art, corresponding to a data rate of 10-200 Gbps with 1-10 GHz system bandwidth. The model is refined to analyze critical sources of power loss in an actual multimode system. The prototype-based measurement results closely follow the theoretical predictions, validating CAP-MIMO theory, and illustrating the utility of the model.

Optimal Resource Allocation in Coordinated Multi-Cell Systems

Abstract: The use of multiple antennas at base stations is a key component in the design of cellular communication systems that can meet high-capacity demands in the downlink. Under ideal conditions, the gai ...

Efficiency Resource Allocation for Device-to-Device Underlay Communication Systems: A Reverse Iterative Combinatorial Auction Based Approach

Abstract: Peer-to-peer communication has been recently considered as a popular issue for local area services. An innovative resource allocation scheme is proposed to improve the performance of mobile peer-to-peer, i.e., device-to-device (D2D), communications as an underlay in the downlink (DL) cellular networks. To optimize the system sum rate over the resource sharing of both D2D and cellular modes, we introduce a reverse iterative combinatorial auction as the allocation mechanism. In the auction, all the spectrum resources are considered as a set of resource units, which as bidders compete to obtain business while the packages of the D2D pairs are auctioned off as goods in each auction round. We first formulate the valuation of each resource unit, as a basis of the proposed auction. And then a detailed non-monotonic descending price auction algorithm is explained depending on the utility function that accounts for the channel gain from D2D and the costs for the system. Further, we prove that the proposed auction-based scheme is cheat-proof, and converges in a finite number of iteration rounds. We explain non-monotonicity in the price update process and show lower complexity compared to a traditional combinatorial allocation. The simulation results demonstrate that the algorithm efficiently leads to a good performance on the system sum rate.

Smart Grid Communication: Its Challenges and Opportunities

Abstract: The necessity to promote smart grid (SG) has been recognized with a strong consensus. The SG integrates electrical grids and communication infrastructures and forms an intelligent electricity network working with all connected components to deliver sustainable electricity supplies. Many advanced communication technologies have been identified for SG applications with a potential to significantly enhance the overall efficiency of power grids. In this paper, the challenges and applications of communication technologies in SG are discussed. In particular, we identify three major challenges to implement SG communication systems, including standards interoperability, cognitive access to unlicensed radio spectra, and cyber security. The issues to implement SG communications on an evolutional path and its future trends are also addressed. The aim of this paper is to offer a comprehensive review of state-of-the-art researches on SG communications.

System access and synchronization methods for mimo ofdm communications systems and physical layer packet and preamble design

Abstract: A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

A Learning Theoretic Approach to Energy Harvesting Communication System Optimization

Abstract: A point-to-point wireless communication system in which the transmitter is equipped with an energy harvesting device and a rechargeable battery, is studied. Both the energy and the data arrivals at the transmitter are modeled as Markov processes. Delay-limited communication is considered assuming that the underlying channel is block fading with memory, and the instantaneous channel state information is available at both the transmitter and the receiver. The expected total transmitted data during the transmitter's activation time is maximized under three different sets of assumptions regarding the information available at the transmitter about the underlying stochastic processes. A learning theoretic approach is introduced, which does not assume any a priori information on the Markov processes governing the communication system. In addition, online and offline optimization problems are studied for the same setting. Full statistical knowledge and causal information on the realizations of the underlying stochastic processes are assumed in the online optimization problem, while the offline optimization problem assumes non-causal knowledge of the realizations in advance. Comparing the optimal solutions in all three frameworks, the performance loss due to the lack of the transmitter's information regarding the behaviors of the underlying Markov processes is quantified.

Tabletop molecular communication: text messages through chemical signals.

Abstract: In this work, we describe the first modular, and programmable platform capable of transmitting a text message using chemical signalling – a method also known as molecular communication. This form of communication is attractive for applications where conventional wireless systems perform poorly, from nanotechnology to urban health monitoring. Using examples, we demonstrate the use of our platform as a testbed for molecular communication, and illustrate the features of these communication systems using experiments. By providing a simple and inexpensive means of performing experiments, our system fills an important gap in the molecular communication literature, where much current work is done in simulation with simplified system models. A key finding in this paper is that these systems are often nonlinear in practice, whereas current simulations and analysis often assume that the system is linear. However, as we show in this work, despite the nonlinearity, reliable communication is still possible. Furthermore, this work motivates future studies on more realistic modelling, analysis, and design of theoretical models and algorithms for these systems.

Stochastic Modeling of THz Indoor Radio Channels

Abstract: Providing the basis for fast system simulations and the adequate design of upcoming THz communication systems, a novel stochastic 300 GHz indoor channel model is introduced. It combines both the modeling in time as well as in frequency domain in order to account for the significant frequency dispersion of ultra broadband THz channels. Not only amplitude, phase and temporal, but also spatial channel information is considered. That way, MIMO systems as well as novel antenna concepts can be simulated. Verified and calibrated frequency domain ray tracing simulations in an office scenario provide the data basis for the derivation of model parameters. Model channel realizations are tested against ray tracing predictions and channel measurements. A complete scenario-specific parameter set is given for the considered environment, so that the model can be implemented for further use and future THz communication links can be designed under consideration of realistic propagation conditions.

A User's Guide to Compressed Sensing for Communications Systems

Abstract: SUMMARY This survey provides a brief introduction to compressed sensing as well as several major algorithms to solve it and its various applications to communications systems. We firstly review linear simultaneous equations as ill-posed inverse problems, since the idea of compressed sensing could be best understood in the context of the linear equations. Then, we consider the problem of compressed sensing as an underdetermined linear system with a prior information that the true solution is sparse, and explain the sparse signal recovery based on � 1 optimization, which plays the central role in compressed sensing, with some intuitive explanations on the optimization problem. Moreover, we introduce some important properties of the sensing matrix in order to establish the guarantee of the exact recovery of sparse signals from the underdetermined system. After summarizing several major algorithms to obtain a sparse solution focusing on the � 1 optimization and the greedy approaches, we introduce applications of compressed sensing to communications systems, such as wireless channel estimation, wireless sensor network, network tomography, cognitive radio,

LED and CMOS Image Sensor Based Optical Wireless Communication System for Automotive Applications

Abstract: An optical wireless communication (OWC) system based on a light-emitting-diode (LED) transmitter and a camera receiver has been developed for use in the automotive area. The automotive OWC system will require Mb/s-class data rates and the ability to quickly detect LEDs from an image. The key to achieving this is improvements to the capabilities of the image sensor mounted on the camera receiver. In this paper, we report on a novel OWC system equipped with an optical communication image sensor (OCI), which is newly developed using CMOS technology. To obtain higher transmission rates, the OCI employs a specialized “communication pixel (CPx)” capable of responding promptly to optical intensity variations. Furthermore, a new quick LED detection technique, based on a 1-bit flag image which only reacts to high-intensity objects, is formulated. The communication pixels, ordinary image pixels, and associated circuits (including 1-bit flag image output circuits) are then integrated into the OCI. This paper describes the design, fabrication, and capabilities of the OCI, as well as the development of the LED and image sensor based OWC system, which boasts a 20-Mb/s/pixel data rate without LED detection and a 15-Mb/s/pixel data rate with a 16.6-ms real-time LED detection.

Physical Layer Security in Wireless Communications

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.

Wireless communication using multi-dimensional antenna configuration

Abstract: Communications may be performed in a communications system using multi-dimensional antenna configurations. A WTRU may receive communications from a base station via one or more channels. The communications may be performed using multiple component codebooks. The WTRU may send channel state information (CSI) feedback for each component codebook to the base station for consideration when performing communications with the WTRU. The WTRU may determine the CSI feedback for each component codebook based on channel measurements. The component codebooks may include a horizontal component codebook and/or a vertical component codebook. The WTRU may send the CSI feedback for each component codebook to the base station independently or in the form of a composite codebook. The WTRU may determine a composite codebook a function of the component codebooks.

Modulation and equalization in an orthonormal time-frequency shifting communications system

Abstract: A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

A Survey of Wireless Communications and Propagation Modeling in Underground Mines

Abstract: Mining and mineral exploration play important roles in the global economy. In mining operations, communication systems play vital roles in ensuring personnel safety, enhancing operational efficiency and process optimization. Over the period 1920-2012, this article surveys the evolution of wireless communications in underground mines, the developments of the underlying technology, and progress in understanding and modeling the underground wireless propagation channel. Current and future trends in technology, applications and propagation modeling are also identified. About ninety relevant references have been reviewed that consider: 1) the emergence of technology and applications, 2) analytical, numerical and measurement-based propagation modeling techniques, and 3) implications of the physical environment, antenna placement and radiation characteristics on wireless communication system design. Affected systems include narrowband, wideband/ultra-wideband (UWB) and multiple-antenna systems. The paper concludes by identifying open areas of research.

Compressive sensing based multi-user detection for machine-to-machine communication

Abstract: With the expected growth of machine-to-machine communication, new requirements for future communication systems have to be considered. More specifically, the sporadic nature of machine-to-machine communication, low data rates, small packets and a large number of nodes necessitate low overhead communication schemes that do not require extended control signaling for resource allocation and management. Assuming a star topology with a central aggregation node that processes all sensor information, one possibility to reduce control signaling is the estimation of sensor node activity. In this paper, we discuss the application of greedy algorithms from the field of compressive sensing in a channel coded code division multiple access context to facilitate a joint detection of sensor node activity and transmitted data. To this end, a short introduction to compressive sensing theory and algorithms will be given. The main focus, however, will be on implications of this new approach. Especially, we consider the activity detection, which strongly determines the performance of the overall system. We show that the performance on a system level is dominated by the missed detection rate in comparison with the false alarm rate. Furthermore, we will discuss the incorporation of activity-aware channel coding into this setup to extend the physical layer detection capabilities to code-aided joint detection of data and activity. Copyright © 2013 John Wiley & Sons, Ltd.

Optimal Scheduling and Power Allocation for Two-Hop Energy Harvesting Communication Systems

Abstract: Energy harvesting (EH) has recently emerged as a promising technique for green communications. To realize its potential, communication protocols need to be redesigned to combat the randomness of the harvested energy. In this paper, we investigate how to apply relaying to improve the short-term performance of EH communication systems. With an EH source and a non-EH half-duplex relay, we consider two different design objectives: 1) short-term throughput maximization; and 2) transmission completion time minimization. Both problems are joint time scheduling and power allocation problems, rendered quite challenging by the half-duplex constraint at the relay. A key finding is that directional water-filling (DWF), which is the optimal power allocation algorithm for the single-hop EH system, can serve as guideline for the design of two-hop communication systems, as it not only determines the value of the optimal performance, but also forms the basis to derive optimal solutions for both design problems. Based on a relaxed energy profile along with the DWF algorithm, we derive key properties of the optimal solutions for both problems and thereafter propose efficient algorithms. Simulation results will show that both time scheduling and power allocation optimizations are necessary in two-hop EH communication systems.

Method and device for measuring interference in communication system

Abstract: A method and a device for measuring interference in a communication system are provided. The method includes measuring interference in a base station of a communication system, in which one or more antenna groups are arranged at different positions in a single cell, includes the steps of determining a reception antenna group which is one of the one or more antenna groups that transmits a signal other than an interference signal to a terminal, determining a reference signal in order to measure the strength of the signal transmitted by the reception antenna group, a step of determining a wireless resource so as to measure the interference in each of the one or more antenna groups, and notifying the terminal with the strength of the signal transmitted by the reception antenna group and information for measuring the interference in each of the one or more antenna groups.

Microcellular communications antenna and associated methods

Abstract: A radio frequency (RF) communications system includes a local RF communications device and an RF antenna including a conical RF launch structure coupled to the local RF communications device, and an elongate electrical conductor having a proximal end coupled to the conical RF launch structure and a distal end spaced apart from the conical RF launch structure to define an elongate RF coverage pattern. The elongate conductor may be a coaxial cable. At least one remote RF communications device, within the elongate RF coverage pattern, wirelessly communicates with the local RF communications device.

Design of Wide-Area Power System Damping Controllers Resilient to Communication Failures

Abstract: Recent research has demonstrated that wide-area signals obtained using synchronized phasor measurements could be more effective than local signals in damping inter-area oscillations in large interconnected systems. To transmit wide-area signals for use in controls, communication systems are required. Communication systems are vulnerable to disruptions as a result of which the reliability of the power system could be jeopardized. In order to counteract communication failures, resiliency could be built in either the communication system or the physical system. In this paper an approach is developed to build resiliency in grid controls in the physical system. The resiliency is achieved by robustly designing a novel redundant two-input single-output (TISO) supplementary damping controller (SDC) associated with a static VAr compensator (SVC) that utilizes both a wide-area signal and a local signal to guarantee that the system is stabilized if the wide-area signal is lost. Numerical tests on the IEEE 50-generator test system have demonstrated that the proposed SDC is effective in stabilizing the system and improving grid control resiliency in response to communication failures.

FASA: accelerated S-ALOHA using access history for event-driven M2M communications

Abstract: Supporting massive device transmission is challenging in machine-to-machine (M2M) communications. Particularly, in event-driven M2M communications, a large number of devices become activated within a short period of time, which in turn causes high radio congestions and severe access delay. To address this issue, we propose a Fast Adaptive S-ALOHA (FASA) scheme for random access control of M2M communication systems with bursty traffic. Instead of the observation in a single slot, the statistics of consecutive idle and collision slots are used in FASA to accelerate the tracking process of network status that is critical for optimizing S-ALOHA systems. With a design based on drift analysis, the estimate of the number of the active devices under FASA converges fast to the true value. Furthermore, by examining the T-slot drifts, we prove that the proposed FASA scheme is stable as long as the average arrival rate is smaller than e-1, in the sense that the Markov chain derived from the scheme is geometrically ergodic. Simulation results demonstrate that under highly bursty traffic, the proposed FASA scheme outperforms traditional additive schemes such as PB-ALOHA and achieves near-optimal performance in reducing access delays. Moreover, compared to multiplicative schemes, FASA shows its robustness under heavy traffic load in addition to better delay performance.

Deep Space Telecommunications Systems Engineering

Abstract: A vital, often predominant function in every space mission is that of communications. From the moment of launch, the only connection between spacecraft and earth is the communications systems. This system is responsible for spending scientific data back to earth in the specified quality and quantity together with engineering data reporting the condition of the spacecraft. The communications system also provides the capability of tracking the spacecraft and commanding it to take certain actions. Without an effective communications system a successful mission would not be possible.

Communication system, base station, and communication method

Abstract: Disclosed is a communication system in which information about the number of active users in each cell can be shared between base stations A communication system according to the present exemplary embodiment includes a first base station controlling a first cell and a second base station connected to the first base station through an inter-base-station interface, wherein the first base station transmits operation information on the first cell to the second base station through the inter-base-station interface, wherein the operation information on the first cell includes information about a load on the first cell and information about the number of active users in the first cell

Multi-mode wlan/pan mac

Abstract: A novel solution is presented in which a MAC (Medium Access Controller) is implemented that includes multiple functionality types This MAC may include functionality supporting communication according to one or more of the IEEE 80211 WLAN (Wireless Local Area Network) related standards and also to one or more of the standards generated by the IEEE 802153 PAN (Personal Area Network) working group By providing this dual functionality of a multi-mode WLAN/PAN MAC, a communication device may adaptively change the manner in which it communicates with other communication devices For example, in an effort to maximize throughput and overall efficiency of communication within a communication system, certain of the various devices may change from using the WLAN related standards to using the PAN related standards, and vice versa, based on any one or more of a variety of operational parameters including system configuration

Interactive Joint Transfer of Energy and Information

Abstract: In some communication networks, such as passive RFID systems, the energy used to transfer information between a sender and a recipient can be reused for successive communication tasks. In fact, from known results in physics, any system that exchanges information via the transfer of given physical resources, such as radio waves, particles and qubits, can conceivably reuse, at least part, of the received resources. This paper aims at illustrating some of the new challenges that arise in the design of communication networks in which the signals exchanged by the nodes carry both information and energy. To this end, a baseline two-way communication system is considered in which two nodes communicate in an interactive fashion. In the system, a node can either send an "onquotedblright symbol (or "1quotedblright), which costs one unit of energy, or an "offquotedblright signal (or "0quotedblright), which does not require any energy expenditure. Upon reception of a "1quotedblright signal, the recipient node "harvestsquotedblright, with some probability, the energy contained in the signal and stores it for future communication tasks. Inner and outer bounds on the achievable rates are derived. Numerical results demonstrate the effectiveness of the proposed strategies and illustrate some key design insights.

Communication System and Method

Abstract: A method of transmitting video data comprising: establishing a bidirectional video channel between a first terminal and a second terminal in a packet-based communication network; beginning a live, face-to-face video call over the established channel by generating first video data from a video camera of the first terminal, transmitting the first video data to the second terminal for display on a screen of the second terminal, receiving second video data generated from a video camera of the second terminal, and displaying the second video data on a screen of the first terminal; generating third video data at the first terminal from a source other than the video camera of the first terminal; receiving a user selection at the first terminal; and in response to the user selection, transmitting the third video data to the second user over the established channel of the packet-based communication network.

Radio base station, user terminal, radio communication system and radio communication method

Abstract: The present invention is designed to make it possible to adequately form the search space candidates to be used in the blind decoding of downlink control information when the radio resource region for downlink control channels is expanded. The radio base station of the present invention is a radio base station that transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, and has a configuring section that configures, for the user terminal, a plurality of resource sets that are each formed by including a plurality of resource blocks allocated to the enhanced downlink control channel, and a determining section that determines enhanced control channel elements to constitute a plurality of search space candidates such that the plurality of search space candidates of each resource set are all placed in different resource blocks.

On Covert Acoustical Mesh Networks in Air

Abstract: Covert channels can be used to circumvent system and network policies by establishing communications that have not been considered in the design of the computing system. We construct a covert channel between different computing systems that utilizes audio modulation/demodulation to exchange data between the computing systems over the air medium. The underlying network stack is based on a communication system that was originally designed for robust underwater communication. We adapt the communication system to implement covert and stealthy communications by utilizing the near ultrasonic frequency range. We further demonstrate how the scenario of covert acoustical communication over the air medium can be extended to multi-hop communications and even to wireless mesh networks. A covert acoustical mesh network can be conceived as a botnet or malnet that is accessible via near-field audio communications. Different applications of covert acoustical mesh networks are presented, including the use for remote keylogging over multiple hops. It is shown that the concept of a covert acoustical mesh network renders many conventional security concepts useless, as acoustical communications are usually not considered. Finally, countermeasures against covert acoustical mesh networks are discussed, including the use of lowpass filtering in computing systems and a host-based intrusion detection system for analyzing audio input and output in order to detect any irregularities.