KTH - Royal Institute of Technology

Displaying 81-120 of 206 results

  • White Papers // May 2011

    MobiSense: Power-Efficient Micro-Mobility in Wireless Sensor Networks

    Emerging applications in industrial automation as well as tracking and monitoring applications of humans, objects or animals share common requirements: micro-mobility, high-throughput, and two-way end-to-end communications. In this paper, the authors present MobiSense, a MAC layer and routing architecture for micro-mobility environments providing reliable and energy-efficient communication and low-latency hand-offs....

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2011

    Bandwidth Efficient Compress-and-Forward Relaying Based on Joint Source-Channel Coding

    The authors propose a new code design for compress-and-forward relaying over bandlimited relay-to-destination channels. The main contribution of this paper is a code design based on joint (source-channel) coding and modulation that uses the correlation between the observations at the relay and the destination as protection against channel errors. This...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2011

    Compress-and-Forward Relaying Based on Symbol-Wise Joint Source-Channel Coding

    The authors propose a new compress-and-forward implementation for the relay channel based on joint source-channel coding techniques. The relay performs scalar quantization of its observation in combination with a redundant index mapping. The system utilizes the correlation between the quantized signal and the direct-link observation of the transmitted symbols as...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2011

    F-Lipschitz Optimization With Wireless Sensor Networks Applications

    Motivated by the need for fast computations in wireless sensor networks, the new F-Lipschitz optimization theory is introduced for a novel class of optimization problems. These problems are defined by simple qualifying properties specified in terms of increasing objective function and contractive constraints. It is shown that feasible F-Lipschitz problems...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    How Far from Kronecker can a MIMO Channel be? Does it Matter?

    A common assumption in the design and analysis of many MIMO transmission schemes is the so-called Kronecker model. This model is often a crucial step to obtain mathematically tractable solutions, but has also been criticized for being unrealistic. In this paper, the authors present a numerical approach to determine a...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    Aeronautical Communication Systems as Potential Primary Users in Secondary Spectrum Access

    Secondary spectrum access emerges as a means to increase spectrum utilization significantly in a near future. However, the technical availability and the economic value of the secondary access have not been fully investigated. Particularly, the impact of the secondary access on the real-life primary systems remains mostly unaddressed. Among the...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    A Low-Overhead Fault-Aware Deflection Routing Algorithm for 3D Network-on-Chip

    This paper proposes a low-overhead fault-tolerant deflection routing algorithm, which uses a layer routing table and two TSV state vectors to make efficient routing decision to avoid both TSV and horizontal link faults, for 3D NoC. The proposed switch is implemented in hardware with TSMC 65nm technology, which can achieve...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    Deployment Strategies in Competitive Wireless Access Networks

    The rapid growth of mobile internet traffic has forced wireless service providers to deploy increasingly higher capacity in their wireless broadband access systems. The flat rate revenue streams in combination with the rapidly growing costs associated with conventional access deployment is usually referred to as the "Revenue gap". In this...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    Session Initiation Protocol and Services

    In this paper, the authors discusses about the Session Initiation Protocol and the call setup between the user agents with scenarios like single proxy server and multiple proxy servers of different domains. The messages and the parameters of those calls are analyzed in detail. Scenarios for a call flow with...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    Adaptively Reconfigurable Controller for the Flash Memory

    As the continuous development on the capacity and work frequency, Programmable Logic Devices (PLD) especially Field-Programmable Gate Arrays (FPGA) is playing an increasingly important role in embedded systems designs. The FPGA market has hit about 3 and 4 billion US dollars respectively in 2009 and 2010, and is expected by...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    Multi-Path Routing Metrics for Reliable Wireless Mesh Routing Topologies

    Several emerging classes of applications that run over wireless networks have a need for mathematical models and tools to systematically characterize the reliability of the network. The authors propose two metrics for measuring the reliability of wireless mesh routing topologies, one for flooding and one for unicast routing. The Flooding...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    Distributed Relative Clock Synchronization for Wireless Sensor Networks

    This paper considers an important problem in sensor networks, i.e. clock synchronization in wireless sensor networks with a focus on those scenarios where the inter-node time-of-arrival measurements are noisy. Initially, a simple convex, constraint based, optimization protocol for the problem of relative clock synchronization in wireless (sensor) networks is presented....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    Converging an Overlay Network to a Gradient Topology

    In this paper, the authors investigate the topology convergence problem for the gossip-based Gradient overlay network. In an overlay network where each node has a local utility value, a Gradient overlay network is characterized by the properties that each node has a set of neighbors with the same utility value...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    Network Estimation and Packet Delivery Prediction for Control Over Wireless Mesh Networks

    Much of the current theory of networked control systems uses simple point-to-point communication models as an abstraction of the underlying network. As a result, the controller has very limited information on the network conditions and performs suboptimally. This work models the underlying wireless multihop mesh network as a graph of...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    On Designing Optimal Servomechanism Controller With Limited Model Information

    The family of limited model information designs, which construct controllers by accessing the plant's model in a constrained manner, is introduced in this paper. The closed-loop constant-disturbance rejection performance of the best Proportional-Integral (PI) controller that they can produce is investigated. For a class of linear discrete-time time-invariant plants, it...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    A Distributed Information Fusion Method for Localization Based on Pareto Optimization

    To overcome the limitations of specific positioning techniques for mobile wireless nodes and achieve a high accuracy, the fusion of heterogeneous sensor information is an appealing strategy. In this paper, the problem of optimal fusion of ranging information typically provided by Ultra-Wideband radio with speed and absolute orientation information is...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    On the Requirements of Secondary Access to 960-1215 MHz Aeronautical Spectrum

    In this paper, the authors investigate the spectrum sharing requirements of secondary access to 960-1215 MHz band which is primarily allocated to aeronautical usage. Primary system of interest is Distance Measuring Equipments (DME) aiding navigation of airplanes. They consider a scenario where indoor femtocells share the spectrum as secondary users....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    Opportunistic Secondary Spectrum Access -Opportunities and Limitations

    Dynamic spectrum sharing technique ("Cognitive Radio") where secondary users opportunistically utilize temporarily or locally unused spectrum has emerged as a prime candidate technology to relieve the perceived spectrum shortage. Making a realistic assessment of the amount of spectrum available for secondary services is the objective of the EU FP7 QUASAR...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    A Mobile World of Security - The Model

    The authors propose a novel approach to establish cryptographic keys among mobile users and a networking infrastructure. Their approach comes at a low cost and can either be used as an alternative to existing solutions or can be employed in a complementary way. Their basic observation is that users are...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    Relay-Aided Broadcasting With Instantaneously Decodable Binary Network Codes

    The authors consider a base-station broadcasting a set of order-insensitive packets to a user population over packet-erasure channels. To improve efficiency they propose a relay-aided transmission scheme using instantaneously-decodable binary network coding. Their proposed scheme ensures that a coded packet can be immediately decoded at the user side without delay....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    Sphere Decoding Complexity Exponent for Decoding Full Rate Codes Over the Quasi-Static MIMO Channel

    In the setting of quasi-static Multiple-Input Multiple-Output (MIMO) channels, the authors consider the high Signal-to-Noise Ratio (SNR) asymptotic complexity required by the Sphere Decoding (SD) algorithm for decoding a large class of full rate linear space-time codes. With SD complexity having random fluctuations induced by the random channel, noise and...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    An Optimization Approach to Joint Cell, Channel and Power Allocation in Multicell Networks

    In multi-cell wireless networks the resource allocation task includes the selection of the serving cell and the allocation of channels and transmission power. While all of these tasks have been studied in the past, all three jointly are seldom addressed. In this paper, the authors formulate the joint cell, channel...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Wireless Networked Control System Co-Design

    A framework for the joint design of wireless network and controllers is proposed. Multiple control systems are considered where the sensor measurements are transmitted to the controller over the IEEE 802.15.4 protocol. The essential issues of wireless Networked Control Systems (NCSs) are investigated to provide an abstraction of the wireless...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Uncoded Transmission in Wireless Relay Networks Using Deterministic Modeling

    The question of how much information can be sent through a wireless communication network and what the optimal strategy would be to achieve the capacity is crucial for the design of future wireless networks, but appears to be very difficult to answer. Modeling the wireless channel in the most common...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Impact of Aggregate Interference on Meteorological Radar From Secondary Users

    In this paper, the authors investigate the impact of aggregate interference in a secondary spectrum access system. Particularly, meteorological radar operating in 5.6 GHz band is considered to be a primary user. Secondary users are WLAN devices spreading in a large area which induce aggregate interference to the radar. They...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Analysis of a Simple Feedback Scheme for Error Correction Over a Lossy Network

    A control theoretic analysis of a simple error correction scheme for lossy packet-switched networks is presented. Based on feedback information from the error correction process in the receiver, the sender adjusts the amount of redundancy using a so called extremum-seeking controller, which does not rely on any accurate model of...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    On Power Control for Wireless Sensor Networks: System Model, Middleware Component and Experimental Evaluation

    In this paper, the authors investigate strategies for radio power control for wireless sensor networks that guarantee a desired packet error probability. Efficient power control algorithms are of major concern for these networks, not only because the power consumption can be significantly decreased but also because the interference can be...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Power and Rate Control Outage Based in CDMA Wireless Networks Under MAI and Heterogeneous Traffic Sources

    The authors characterize the maximum throughput achievable for the up-link of a power-controlled WCDMA wireless system with variable spreading factor. The system model includes multi access interference caused by users with heterogeneous data sources, and quality of service expressed in terms of outage probability. Inner loop and outer loop power...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    ICT Investment Evaluation and Mobile Computing Business Support for Construction Site Operations

    The intangible qualitative innovation benefits of Information and Communication Technology (ICT) are essential for improving quality of production, enhancing business activities and creating new competitive opportunities. Still, these benefits are not accounted for in traditional financial investment evaluation methods like Return On Investment (ROI) and Net Present Value (NPV). The...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Sphere Decoding Complexity Exponent for Full Rate Codes Over the Quasi-Static MIMO Channel

    In the setting of quasi-static Multiple-Input Multiple-Output (MIMO) channels, the authors consider the high Signal-to-Noise Ratio (SNR) asymptotic complexity required by the Sphere Decoding (SD) algorithm for decoding a large class of full rate linear space-time codes. With SD complexity being a function of the code and having random fluctuations...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Power and Rate Control Outage Based in CDMA Wireless Networks Under MAI and Heterogeneous Traffic Sources

    The authors characterize the maximum throughput achievable for the up-link of a power-controlled WCDMA wireless system with variable spreading factor. Their system model includes multi access interference caused by users with heterogeneous data sources, and quality of service expressed in terms of outage probability. Inner loop and outer loop power...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    On Security Indices for State Estimators in Power Networks

    In this paper, the authors study stealthy false-data attacks against state estimators in power networks. The focus is on applications in SCADA (Supervisory Control And Data Acquisition) systems where measurement data is corrupted by a malicious attacker. They introduce two security indices for the state estimators. The indices quantify the...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Analytical Modeling of IEEE 802.15.4 for Multi-Hop Networks With Heterogeneous Traffic and Hidden Terminals

    IEEE 802.15.4 multi-hop wireless networks are an important communication infrastructure for many applications, including industrial control, home automation, and smart grids. Existing analysis of the IEEE 802.15.4 Medium Access Control (MAC) protocol are often based on assumptions of homogeneous traffic and ideal carrier sensing, which are far from the reality...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Advances in Wireless Network Coding for IMT-Advanced & Beyond

    In a classical network, data streams originating from a source and intended to a desired destination are routed through intermediate nodes before reaching their final destination. By contrast, Network Coding (NC) manipulates at an intermediate node those data streams by combining the data from the streams before forwarding it to...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Experimental Investigation of TDD Reciprocity-Based Zero-Forcing Transmit Precoding

    The authors describe an implementation of TDD reciprocity based zero-forcing linear pre-coding on a wireless testbed. A calibration technique which self-calibrates the base-station without the need for help from other nodes is described. Performance results in terms of downlink channel estimation error as well as Bit Error Rate (BER) and...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Large Firm Dynamics On The Nordic-Baltic Scene Implications For Innovation And Growth

    This paper investigates the role of the 30 largest firms in the respective Nordic country and in Estonia over the last decade and for some variables between 1975 to 2006. The analysis confirms that the largest firms play a critically important role for industrial dynamics in the Nordic countries. Statistics...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    Memory Architecture and Management in an NoC Platform

    The memory organization and the management of the memory space is a critical part of every NoC based platform design. The authors propose a Data Management Engine (DME), which is a block of programmable hardware and part of every processing element. It off-loads the processing element (CPU, DSP, etc.) by...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    Distributed Monitoring and Resource Management for Large Cloud Environments

    Over the last decade, the number, size and complexity of large-scale networked systems has been growing fast, and this trend is expected to accelerate. The best known example of a large-scale networked system is probably the internet, while large datacenters for cloud services are the most recent ones. In such...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    Group Message Authentication

    Group signatures is a powerful primitive with many practical applications, allowing a group of parties to share a signature functionality, while protecting the anonymity of the signer. However, despite intensive research in the past years, there is still no fully satisfactory implementation of group signatures in the plain model. The...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    Analysis of User Plane in IEEE 802.11b/g QoS Networks

    In this paper, the authors present the performances evaluation of infrastructure 802.11b/g QoS networks, in both HCF (Hybrid Coordination Function) operating modes: EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). Besides comparing these two modes in terms of total network throughput (between themselves as well as against...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    Analysis of User Plane in IEEE 802.11b/g QoS Networks

    In this paper, the authors present the performances evaluation of infrastructure 802.11b/g QoS networks, in both HCF (Hybrid Coordination Function) operating modes: EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). Besides comparing these two modes in terms of total network throughput (between themselves as well as against...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    Sphere Decoding Complexity Exponent for Decoding Full Rate Codes Over the Quasi-Static MIMO Channel

    In the setting of quasi-static Multiple-Input Multiple-Output (MIMO) channels, the authors consider the high Signal-to-Noise Ratio (SNR) asymptotic complexity required by the Sphere Decoding (SD) algorithm for decoding a large class of full rate linear space-time codes. With SD complexity having random fluctuations induced by the random channel, noise and...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    ICT Investment Evaluation and Mobile Computing Business Support for Construction Site Operations

    The intangible qualitative innovation benefits of Information and Communication Technology (ICT) are essential for improving quality of production, enhancing business activities and creating new competitive opportunities. Still, these benefits are not accounted for in traditional financial investment evaluation methods like Return On Investment (ROI) and Net Present Value (NPV). The...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    Distributed Relative Clock Synchronization for Wireless Sensor Networks

    This paper considers an important problem in sensor networks, i.e. clock synchronization in wireless sensor networks with a focus on those scenarios where the inter-node time-of-arrival measurements are noisy. Initially, a simple convex, constraint based, optimization protocol for the problem of relative clock synchronization in wireless (sensor) networks is presented....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Oct 2011

    Aggregate Interference in Secondary Access With Interference Protection

    This paper presents a derivation of the probability distribution function (pdf) of the aggregate interference in a secondary access network where multiple secondary users cause interference to a single primary user. The derivation considers a practical interference protection mechanism that the transmission of each secondary user is regulated by an...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jul 2011

    Aggregate Interference From Secondary Users With Heterogeneous Density

    This paper presents an analytical model to approximate the probability distribution function of the aggregate interference that a primary user receives from multiple secondary transmitters. In particular, the authors consider heterogeneity in spatial distribution of secondary users such that there are several sites with densely populated secondary users in the...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jun 2011

    Optimal Power Allocation in Multi-Hop Cognitive Radio Networks

    Optimal power allocation in a multi-hop cognitive radio network is investigated. Information transmitted from the source passes through several wireless relay nodes before reaching the destination. At each hop, the received signal is decoded, re-encoded and retransmitted to the following node. Transmissions at every hop are overheard by nearby nodes...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    Opportunistic Secondary Spectrum Access -Opportunities and Limitations

    Dynamic spectrum sharing technique ("Cognitive Radio") where secondary users opportunistically utilize temporarily or locally unused spectrum has emerged as a prime candidate technology to relieve the perceived spectrum shortage. Making a realistic assessment of the amount of spectrum available for secondary services is the objective of the EU FP7 QUASAR...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2011

    Geo-Location Spectrum Opportunities Database in Downlink Radar Bands for OFDM Based Cognitive Radios

    In this paper a model to investigate the spectrum opportunities for cognitive radio networks in three radar frequency bands L, S and C at a specific location is introduced. The authors consider underlay unaware spectrum sharing model. The Secondary System they assume is an OFDM based system. The followed strategy...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    Aeronautical Communication Systems as Potential Primary Users in Secondary Spectrum Access

    Secondary spectrum access emerges as a means to increase spectrum utilization significantly in a near future. However, the technical availability and the economic value of the secondary access have not been fully investigated. Particularly, the impact of the secondary access on the real-life primary systems remains mostly unaddressed. Among the...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2011

    On the Requirements of Secondary Access to 960-1215 MHz Aeronautical Spectrum

    In this paper, the authors investigate the spectrum sharing requirements of secondary access to 960-1215 MHz band which is primarily allocated to aeronautical usage. Primary system of interest is Distance Measuring Equipments (DME) aiding navigation of airplanes. They consider a scenario where indoor femtocells share the spectrum as secondary users....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Impact of Aggregate Interference on Meteorological Radar From Secondary Users

    In this paper, the authors investigate the impact of aggregate interference in a secondary spectrum access system. Particularly, meteorological radar operating in 5.6 GHz band is considered to be a primary user. Secondary users are WLAN devices spreading in a large area which induce aggregate interference to the radar. They...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2011

    Design and Analysis of Relay-aided Broadcast using Binary Network Codes

    The authors consider a base-station broadcasting a set of order-insensitive packets to a user population over packet-erasure channels. To improve efficiency they propose relay-aided transmission using instantaneously-decodable binary network coding. The proposed coding schemes have the benefits of minimal decoding delay and low complexity. They further analyze the performance of...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jun 2011

    On the Throughput of Wireless Interference Networks with Limited Feedback

    Considering a single-antenna M-user interference channel with symmetrically distributed channel gains, when the Channel State Information (CSI) is globally available, applying the ergodic interference alignment scheme, each transmitter-receiver pair achieves a rate proportional to 1:2 of a single user's interference-free achievable rate. This is substantially higher than the achievable rate...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2011

    Outage Performances for Amplify-and-Forward, Decode-and-Forward and Cooperative Jamming Strategies for the Wiretap Channel

    In this paper, the authors investigate the wiretap channel in the presence of a cooperative relay node. They analyze and compare the outage performance of three cooperatives schemes: Cooperative Jamming (CJ), Decode-and-Forward (DF), and Amplify-and-Forward (AF) for the Rayleigh slow fading channel. In particular, they derive a closed-form expression for...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2011

    Bandwidth Efficient Compress-and-Forward Relaying Based on Joint Source-Channel Coding

    The authors propose a new code design for compress-and-forward relaying over bandlimited relay-to-destination channels. The main contribution of this paper is a code design based on joint (source-channel) coding and modulation that uses the correlation between the observations at the relay and the destination as protection against channel errors. This...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Aug 2010

    Capacity Bounds for Relay-Aided Wireless Multiple Multicast with Backhaul

    The authors investigate the capacity bounds for relay-aided two-source two-destination wireless networks with backhaul support between source nodes. Each source multicasts its own message to all destinations with the help of an intermediate relay node, which is full-duplex and shared by both sources. They are aiming to characterize the capacity...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jan 2011

    Uncoded Transmission in Wireless Relay Networks Using Deterministic Modeling

    The question of how much information can be sent through a wireless communication network and what the optimal strategy would be to achieve the capacity is crucial for the design of future wireless networks, but appears to be very difficult to answer. Modeling the wireless channel in the most common...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Aug 2009

    Optimized Analog Network Coding Strategies for the White Gaussian Multiple-Access Relay Channel

    The authors consider a Gaussian multiple-access relay channel with multiple sources, a relay and a destination. They assume that the received signals at the relay and the destination from different nodes are orthogonal. Additionally, they assume that the relay performs an instantaneous mapping to compress all received signals from different...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2009

    Analog Network Coding Mappings in Gaussian Multiple-Access Two-Hop Channels

    The authors consider the multiple-access two-hop channel where two source nodes transmit to a destination node via a relay node. The relaying function is memoryless, in contrast to the conventional schemes based on coding with long codewords. That is, they model the operation of the relay as a two-to-one deterministic...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2010

    Optimal Link Scheduling and Channel Assignment for Convergecast in Linear WirelessHART Networks

    There is a strong current interest in migrating substantial parts of the traditionally wired industrial infrastructure to wireless technologies to improve flexibility, scalability, and efficiency. However, concerns about network latency, reliability and security along with the lack of device interoperability have hampered the deployment rate. To address these concerns, WirelessHART,...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Feb 2011

    A Mobile World of Security - The Model

    The authors propose a novel approach to establish cryptographic keys among mobile users and a networking infrastructure. Their approach comes at a low cost and can either be used as an alternative to existing solutions or can be employed in a complementary way. Their basic observation is that users are...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Apr 2011

    How Far from Kronecker can a MIMO Channel be? Does it Matter?

    A common assumption in the design and analysis of many MIMO transmission schemes is the so-called Kronecker model. This model is often a crucial step to obtain mathematically tractable solutions, but has also been criticized for being unrealistic. In this paper, the authors present a numerical approach to determine a...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    Delay-Constrained Maximum Reliability Routing Over Lossy Links

    This paper studies the problem of joint routing and transmission scheduling for reliable real-time communication over lossy networks. The authors impose a strict latency bound on the packet delivery from source to destination and develop transmission scheduling policies that maximize the probability that the packet is delivered within the specified...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    CSI Acquisition Concepts for Advanced Antenna Schemes in the WINNER+ Project

    This paper summarizes four novel advanced antenna concepts explored in the framework of the WINNER+ project. The concepts are related to multiuser MIMO communication in cellular networks, focusing on the acquisition and application of Channel State Information (CSI) at the transmitter in Time-Division-Duplex (TDD) mode. The concepts include new ideas...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Jul 2009

    Time Allocation in Wireless Network Coding

    Network coding is attracting significant research interest from the academic and industrial research communities, mainly due to its simplicity of application and the large number of applications it can be suited for. Recently, more works have been targeting wireless network coding as the broadcast properties of the wireless medium render...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Advances in Wireless Network Coding for IMT-Advanced & Beyond

    In a classical network, data streams originating from a source and intended to a desired destination are routed through intermediate nodes before reaching their final destination. By contrast, Network Coding (NC) manipulates at an intermediate node those data streams by combining the data from the streams before forwarding it to...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2009

    Opportunistic Relay Selection for Wireless Network Coding

    Owing to its potential of enhancing the network performance and to the large number of applications it can be suited for, wireless network coding is attracting a lot of interest from both the academic and the industrial communities. A common assumption in most of the literature is the presence of...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Nov 2010

    On the Use of Compressive Sampling for Wide-Band Spectrum Sensing

    In a scenario where a cognitive radio unit wishes to transmit, it needs to know over which frequency bands it can operate. It can obtain this knowledge by estimating the power spectral density from a Nyquist-rate sampled signal. For wide-band signals sampling at the Nyquist rate is a major challenge...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    Feedback Design in Multiuser MIMO Systems Using Quantization Splitting and Hybrid Instantaneous/Statistical Channel Information

    In the design of next generation multiuser communication systems, multiple antenna transmission is an essential part providing spatial multiplexing gain and allowing efficient use of resources. A major limiting factor in the resource allocation is the amount of Channel State Information (CSI) available at the transmitter, particularly in multiuser systems...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Dec 2010

    Experimental Investigation of TDD Reciprocity-Based Zero-Forcing Transmit Precoding

    The authors describe an implementation of TDD reciprocity based zero-forcing linear pre-coding on a wireless testbed. A calibration technique which self-calibrates the base-station without the need for help from other nodes is described. Performance results in terms of downlink channel estimation error as well as Bit Error Rate (BER) and...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    Experimental Verification of Indoor TV White Space Opportunity Prediction Model

    Recent work has demonstrated that the underutilized spectrum in the Digital Television Bands, commonly referred to as TV White Space (TVWS), is a prime candidate for Opportunistic Spectrum Access (OSA). However, a systematic assessment of the availability of this spectrum for secondary transmission was, until very recently, lacking. In a...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    Distributed Multichannel Random Access Networks With Selfish Users

    Dynamic Spectrum Access (DSA) schemes allow the users to share spectrum resources by taking advantage of the variations in spectrum demand over time and space. Carrying out dynamic spectrum allocation centrally, however, can be a complex task. For this reason, distributed schemes in which users can access the available channels...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2012

    On the Exact Solution to a Smart Grid Cyber-Security Analysis Problem

    This paper considers a smart grid cyber-security problem analyzing the vulnerabilities of electric power networks to false data attacks. The analysis problem is related to a constrained cardinality minimization problem. The main result shows that an l relaxation technique provides an exact optimal solution to this cardinality minimization problem. The...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2012

    Modeling and Optimization of the IEEE 802.15.4 Protocol for Reliable and Timely Communications

    Distributed processing through ad hoc and sensor networks is having a major impact on scale and applications of computing. The creation of new cyber-physical services based on wireless sensor devices relies heavily on how well communication protocols can be adapted and optimized to meet quality constraints under limited energy resources....

    Provided By KTH - Royal Institute of Technology

  • White Papers // Sep 2010

    Gossip-Based Resource Management for Cloud Environments

    The authors address the problem of resource management for a large-scale cloud environment that hosts sites. Their solution centers around a middleware architecture, the key element of which is a gossip protocol that meets their design goals: fairness of resource allocation with respect to hosted sites, efficient adaptation to load...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Mar 2012

    Modeling and Estimation of Partially Observed WLAN Activity for Cognitive WSNs

    Efficient communication in the crowded ISM band requires the communication networks to be aware of the networking environment and to control their communication protocols accordingly. In this paper, the authors address the issue of efficient WSN communication under WLAN interference. They propose analytic models to describe the WLAN idle time...

    Provided By KTH - Royal Institute of Technology

  • White Papers // Aug 2012

    A Novel Overlay IDS for Wireless Sensor Networks

    Wireless Sensor Network (WSN) consists of low cost sensor nodes which cannot afford to implement sophisticated security system in it. That is why intrusion detection architecture for WSN is considerably different and difficult to implement. Most of the current implementations are based on exchanging anomaly signals among the leaf level...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2012

    Design of Green Optical Networks With Signal Quality Guarantee

    Energy consumption of communication networks is growing very fast due to the rapidly increasing traffic demand. Consequently, design of green communication networks gained a lot of attention. In this paper, the authors focus on optical Wavelength Division Multiplexing (WDM) networks, able to support this growing traffic demand. Several Energy-Aware Routing...

    Provided By KTH - Royal Institute of Technology

  • White Papers // May 2012

    On Combined Beamforming and OSTBC Over the Cognitive Radio Z-Channel With Partial CSI

    The authors consider a pair of Secondary nodes (SU) coupled, in Z-topology, with multiple pairs of Primary nodes (PU). The secondary (cognitive) transmitter is combining Beamforming with Orthogonal Space-Time Block Coding (BOSTBC) and operates under Quality-of-Service (QoS) constraints that must be guaranteed for the Primary Receivers (PURx). The cognitive link...

    Provided By KTH - Royal Institute of Technology