This article proposes a novel preprocessing technique for radar-based short-range gesture sensing using a frequency modulated continuous wave (FMCW) radar. The preprocessing is lightweight and works without Fourier transformation. The signal after preprocessing represents the backscattering central dynamics of the hand as a complex-valued time signal of a point target. It is shown that the proposed processing provides competitive classification results compared to conventional frequency domain-based solutions, while being less computationally intensive and having better generalization performance. The preprocessed time domain signal preserves a high-temporal resolution of the hand movement. Due to this fact, it is possible to integrate a periodic control gesture into the system. In doing so, the system not only detects that a gesture is performed continuously and periodically, but also estimates its speed. This is an essential property for controlling scalable parameters, such as brightness or volume, at different speeds. The real-time capability was proven on a Raspberry Pi 3B with an ARM Cortex-A53 CPU. The proposed processing causes a CPU utilization of only 6%. The neural network (NN) inference is done within 75 ms with a classification accuracy of 96.7%.

In this paper, we present an integrated system-on-module for design-space exploration of neurosynaptic behavior in non-volatile memory enhanced spiking neural networks. The system operates in locally-analog, globally-digital modus, facilitating the exploration and validation of both, individual computational components, and the characteristic spike-based features of neurosynaptic arrays. The key advantage of the system lies in its reconfigurable, adaptable, and interchangeable components, which enable precise and reproducible firing patterns. By leveraging these capabilities, various aspects of neurosynaptic behavior can be examined and manipulated. To enhance the weight retention mechanism, the platform incorporates embedded resistive-RAM, ensuring the preservation of synaptic weights. This integration further supports the accurate representation and processing of synaptic information. Experimental results in 28 nm CMOS technology demonstrate the feasibility and effectiveness of the proposed methodology in characterizing spiking neural network components.

The evolution of wireless communication points to increasing demands on throughput for data-intensive applications in modern society. Integrated millimeter-wave systems with electrical beam-steering capabilities are promising candidates for wireless technologies of the future and are currently the subject of widespread academic and commercial research. The$D$-band, ranging from 110–170 GHz, offers high aggregate bandwidths (BWs), low atmospheric absorption, and multi-GHz operation at amenable fractional BWs. It, therefore, has the potential to foster efficient, highly integrated wireless-communication systems with data rates approaching 100 Gb/s. This article reviews all aspects of hardware integration against the backdrop of an extensive literature review and outlines the challenges and possible solutions for practical 6G wireless systems in the$D$-band. To this end, this article covers a number of related topics in depth, which includes system definition, possible radio architectures and array configurations, the scope and potential of integrated circuit (IC) technologies, the design and characterization of key circuit blocks, advances in antenna and packaging technologies for high-frequency systems, and an overview of measurement techniques currently employed at$D$-band frequencies. A system-level study based on radio-link simulations of different single-carrier quadrature amplitude modulation (QAM) schemes is presented, which quantifies that the impact physical nonidealities, such as signal-to-noise ratio, phase noise, intermodulation distortion, and amplitude and phase imbalances in quadrature signal paths, have on bit-error rates in broadband$D$-band communication systems. This is followed by a comparative assessment of different arrayed-system configurations that include traditional phased arrays, the use of polarization diversity for the transmission of different or identical data streams, and multiple input multiple output (MIMO) operation. The article also presents an overview of possible transceiver architectures for implementing beam-steering arrays and an outline of the associated tradeoffs. The beam-squinting effect seen in large arrays is also investigated in detail. On the implementation front, we present a comparison between different integrated-circuit technologies for high-frequency applications. These include CMOS and SiGe bipolar complementary metal oxide semiconductor (BiCMOS) heterojunction bipolar transistors (HBTs) in silicon technologies, and MOSFETs, HBTs, and HEMTs in III–V technologies, such as InP and GaAs. Implementation challenges are then addressed, and these include the design of high-frequency circuits in the latest IC technologies, current advances in antenna and packaging technologies, and emerging solutions for hybrid integration. The article also details the design and characterization of critical$D$-band transceiver circuit blocks, namely, power and low-noise amplifiers, mixers, phase shifters, passive components for quadrature-phase generation, and radiators exploring hybrid antennas, which we have developed over the course of the past five years. These results compliment the literature survey with comparisons with state-of-the-art designs and are applied to radio-link simulations to predict the performance of practicable wireless links.

In this paper, we introduce a novel design for test (DFT) concept to check the compliance of wireless-body-area-network devices for medical applications with the spectral mask for IR-UWB and FM-UWB defined in chapter 9.13 of the IEEE Std. 802.15.6-2012. The design enables a fast and repeatable IC-production test solution for medium to high volume testing, which is independent of the tester type and does not need any extra circuitry on a test board / device interface board.

Automatic radar based classification of automotive targets, such as pedestrians and cyclist, poses several challenges due to low inter-class variations among different classes and large intra-class variations. Further, different targets required to track in typical automotive scenario can have completely varying dynamics which gets challenging for tracker using conventional state vectors. Compared to state-of-the-art using independent classification and tracking, in this paper, we propose an integrated tracker and classifier leading to a novel Bayesian framework. The tracker’s state vector in the proposed framework not only includes the localization parameters of the targets but is also augmented with the targets’s feature embedding vector. In consequence, the tracker’s performance is optimized due to a better separability of the targets. Furthermore, the classifier’s performance is enhanced due to Bayesian formulation utilizing the temporal smoothing of classifier’s embedding vector.

An integrated circuit (IC) for decoupling of multiple-input multiple-output (MIMO) antennas as well as for aperture and impedance tuning is demonstrated in this paper. The IC decouples the adjacent stripes of the inverted-F antenna (IFA) forming the two separate IFAs for MIMO operation in middle- and high-cellular frequency bands. For low-band operation the IC joins the stripes, forming a single IFA with double the physical length. The same IC is also used for impedance and aperture tuning of the antennas. The IC is designed and fabricated in dedicated 130 nm RF switch technology. The design and measurement results are presented in the paper.

With the emerging 5G solutions for vehicular networking, the spectrum of radio communication technologies also extends into the mmWave band. This is further supported by the recent move towards RADar based COMmunication (RADCOM), i.e., the deeply integrated use of the 77 GHz band for communication and sensing. mmWave communication has widely been explored both analytically as well as in experiments, particularly for indoor usage and semi-stationary outdoor scenarios. In this paper, we explore the capabilities of existing simulators for the vehicular use case. We selected WinProp using deterministic ray-tracing techniques and NYUSIM relying on stochastic simulation of the channel. We compare both with a strong focus on simulation accuracy, usability, and computational performance.

The use of millimeter wave communication gets more and more attention with the growth of 5G, particularly with regard to promising applications like platooning or intersection assistant. However, for the design of those applications, a clear understanding of the channel behaviour at these frequencies is mandatory. Aiming to fill the gap of missing channel models for frequencies above 60 GHz, this paper investigates the channel characteristics necessary for future vehicular applications. Based on the commercially available channel simulation tool WinProp, Altair, a typical vehicular scenario in the city center of Berlin (Germany) is analysed. The simulation results are verified with channel sounding measurements at 60 GHz. Hereby, the dependency of the channel with respect to scatterers like trucks and cars is evaluated. Reflection paths were found to be up to 30 dB higher in received power compared to scattering ones. Further, a platooning scene, consisting of 20 vehicles driving towards each other while communicating, is investigated for various time steps and receiver points. In this context, different antenna types are introduced to reduce interfering signals nearby the major transmitter, achieving a decrease in interference power of up to 20 dB.

This paper presents a parametric variational autoencoder-based human target detection and localization framework working directly with the raw analog-to-digital converter data from the frequency modulated continuous wave radar. We propose a parametrically constrained variational autoencoder, with residual and skip connections, capable of generating the clustered and localized target detections on the range-angle image. Furthermore, to circumvent the problem of training the proposed neural network on all possible scenarios using real radar data, we propose domain adaptation strategies whereby we first train the neural network using ray tracing based model data and then adapt the network to work on real sensor data. This strategy ensures better generalization and scalability of the proposed neural network even though it is trained with limited radar data. We demonstrate the superior detection and localization performance of our proposed solution compared to the conventional signal processing pipeline and earlier state-of-art deep U-Net architecture with range-doppler images as inputs.

In this paper, an overall concept for a joint communication-sensing system at 77 GHz is presented with special focus on the communication part. To take advantage of the reduced interference between vehicles, code division multiplexing using direct sequence spread spectrum signals is applied. The system, which covers the whole signal processing chain, is introduced, explained and simulated using Simulink/Matlab software. A design, capable of spreading, modulating, including non-idealities of radio frequency-blocks and synchronization, is built up and evaluated. Additionally, a channel model is simulated in the software WinProp and integrated in the Simulink simulation. In consequence, a more realistic model compared to an estimation-based Rician-or Rayleigh channel model is realized. Furthermore, different modulation schemes, binary phase shift keying, 4- and 16-quadrature amplitude modulation, are investigated. The system is rated with respect to the bit-error-rate by applying additive white Gaussian noise. The functionality is verified as the the results match with the theoretical assumptions The system is further improved by building up a Rake-Receiver structure.

State of the art automotive systems demand smart system integration like the pre-crash systems and predictive driver assistance features to improve safety and reduce the injuries to pedestrians in addition to drivers and passengers in cars. The pedestrian protection has increased demand in all the cars. From a discrete solution in the last decade, state of the art systems, try to configure traditional Squib drivers to activate highly inductive solenoids to reduce injuries to pedestrians. These smart systems are the Active Hood Lift Systems. Pedestrian fatalities are mainly due to head injuries during a collision with a moving vehicle. To activate these solenoids a regulated current of 1.3A for 2ms is provided so that the rear part of the hood can be lifted to reduce pedestrian fatalities. Inductance range of solenoids is 3mH unlike the squib driver where the inductance is less than 100μH. When the driver turns OFF, the inductive flyback levels can be lower than ground for several hundreds of μs unlike squib drivers where this is only for tens of μs. To provide the free-wheeling current and limit the flyback level from flying far below ground, some solenoids have an in built Schottky diode. Other solutions use an external Schottky diode or integrated power diodes. This is expensive and the paper presented here presents a unique and cheaper solution where the free-wheeling current is provided by the driver itself by activating an on chip parasitic bipolar path. Flyback level is limited to -2V. This is verified in a 4 channel squib driver fabricated in a 40V, 0.35μM BiCMOS process.

We presented an approach to detect and count occupants using a fusion of environmental sensors from an indoor air quality measurement system. Environmental sensors, as opposed to motion detectors, are nonintrusive, easy to install, low cost, detect nonmoving occupants, do not have dead spots, and can even infer the number of occupants. For this paper, we conducted measurements of carbon dioxide, volatile organic compounds (VOCs), air temperature, and air relative humidity in four student apartments for a total of 49 days. We extracted features from the environmental sensors and selected subsets using correlation-based feature selection. Subsequently, we performed a comparison of the supervised learning models repeated incremental pruning to produce error reduction, naïve Bayes (NB), C4.5 decision tree, logistic regression, k-nearest neighbors, and random forest. We further proposed a method to greatly reduce time and effort of collecting training data in residential buildings. The results indicated that the predictive power of VOC sensing is comparable to that of carbon dioxide. With a simple NB classifier, our approach detected occupancy and estimated the number of occupants with an accuracy of 81.1 % and 64.7 %, respectively.

In this paper, we propose a robust minimum maximum mean square error Tomlinson-Harashima precoding (Min-Max-MSE THP) scheme and a low-complexity robust Min-Max-MSE hierarchical linear/THP (HL-THP) scheme for downlink massive multiuser multiple-input-multiple-output (MU-MIMO) systems with imperfect channel state information (CSI) at the transmitter. The proposed robust Min-Max-MSE HL-THP scheme comprises an inner linear beamformer (BF), which is designed based on second-order CSI statistics, and outer THP modules, which exploit the instantaneous overall CSI of the cascade of the actual channel and the inner BF. Thereby, the user terminals are divided into groups, where for each group a THP module successively mitigates the intra-group interference, whereas the inter-group interference is canceled by the inner BF. To ensure fairness, we adopt the maximization of the asymptotic signal-to-leakage-plus-noise ratio in the large system limit and the Min-Max-MSE as an optimization criterion for designing the inner BF and the per-group THP modules, respectively. Our analytical and simulation results show that the proposed robust Min-Max-MSE HL-THP scheme achieves a substantially improved performance in terms of the Max-MSE, maximum bit error rate, and minimum rate compared to linear regularized zero-forcing precoding. Moreover, the performance loss of the proposed robust Min-Max-MSE HL-THP scheme compared to the robust Min-Max-MSE THP scheme is small. In addition, our complexity analysis reveals that the proposed robust Min-Max-MSE HL-THP scheme has a much lower computational complexity than the Min-Max-MSE THP scheme. Hence, the robust Min-Max-MSE HL-THP scheme provides a favorable tradeoff between complexity and performance.

This paper presents a novel dual-band class-E/F power amplifier (PA) with switchable output power. It is targeted to work in a BPSK/OOK transmitter in smart facility applications like an autarkic asset-tracking system based on small sensor nodes. The amplifier is fully-integrated and able to operate at both 434 MHz and 868 MHz without the need for additional inductors, making the design very area-efficient. The output power settings at 868 MHz are controllable between -1.79 dBm and -24.61 dBm at 4.96 mA and 1.43 mA current consumption, respectively. The whole circuit including all inductors and the matching network in front of the antenna consumes only 0.9 mm2 chip area and is fully integrated in a 180 nm CMOS process together with a VCO and a PLL.

This paper presents the dimensioning as well as the comparison of common compensation topologies for inductive power transfer (IPT) systems. A compensation is needed on the primary as well as the secondary side. It consists of a capacitor (parallel or series) in the simplest case or a combination of reactive components (like LCC). This work is the first compilation of the dimensioning, considering all potential combinations of these three compensation possibilities. The five most promising solutions are simulated and the results are compared for constant current- and voltage-operation with varying loads as well as different coupling factors. Finally the different topologies are compared by selected criteria and evaluated accordingly.

A monolithic low noise variable gain amplifier (LNA) operating at 60 GHz is presented. It is designed for a sixport receiver, which is completely integrated on a single chip. These chips are build in highly miniaturized sensors to measure distances with radar. Therefore a high performance LNA is indispensable. The circuit has been designed using a new 0.13 μm SiGe BiCMOS process from IHP (SG13G2). For implementation a three stage architecture is chosen. Measurements show a tuneable gain from 16 to 24 dB at 60 GHz, an input matching of -17 dB and an output matching of -14 dB. The circuit consumes 13 mA from a 3.3 V supply.

After the occurrence of a disaster one of the main needs for the rescue teams and volunteer helpers is a functional communication infrastructure even during the first hours. The disaster recovery system (DRS) originally presented by us in a previous work [1] is based on an IEEE 802.11s wireless mesh network which is set up by non damaged legacy, mesh capable and battery powered devices still available in the disaster region. For lifetime enhancement, which is a key challenge for the proposed DRS based on battery powered devices, a distributed algorithm was proposed which enhances the lifetime of such a system by an approach which allows to shut down non necessary nodes and to keep them for a later usage while still keeping network connectivity. A simulation based proof of concept of this algorithm has been given in [1], however, employing a rather high level of abstraction. In this paper we evaluate the DRS network performance using a full implementation of the distributed algorithm within the simulation and which is based on alternating sleep and awake states for each individual node. Additionally, the algorithm is extended by a novel approach whereby the decision when a node changes its state from sleep to awake or vice-versa is based on the number of neighbors of the corresponding node, allowing for a much simpler implementation on the individual mesh nodes. The achievable lifetime enhancement first is evaluated through a Monte-Carlo simulation. Finally, the network performance achievable with the proposed lifetime enhancement algorithm for disaster recovery systems (LEA-DRS) is validated by a network simulation in ns-3 evaluating a Voice over IP connection between two nodes (e.g. between two rescuers).

This work presents an intelligent analog image sensor system for smart camera applications with the need of edge or marker detection. The system consists of a 3×3 read-out CMOS image sensor, an analog Sobel stage and additional circuitry like operational amplifiers and comparators to compute a 1 bit image with the edges present in the taken photo. This information can then be further processed digitally to detect specific shapes in order to control robot routines, for example. The architecture of the proposed system is highly desirable as dedicated analog hardware has significant advantages in terms of power and speed compared to digital implementations. The overall system is simulated with the help of a 3×3 CMOS image sensor IC as well as Cadence Virtuoso for analog circuit simulation and MATLAB to convert the sequential information back to an image, and compared to other state of the art CMOS image sensors with edge detection capability. The analog Sobel circuit runs with a clock of 10 MHz and consumes less than 0.79 mW average power for the computation of the example image, and the whole 200×200 pixel image sensor consumes only 5.5 mW at a frame rate of 75 fps.

The gain of a digitally controlled oscillator (DCO) represents a crucial parameter for wideband phase modulators utilized in polar transmitters supporting SC-FDMA in LTE uplink. Accurate normalization of the DCO gain is necessary for a two-point modulation of a RF digital phase-locked loop (DPLL) to not degrade the in-band modulation quality and out-of-band emissions. The DCO gain can change due to process, voltage and temperature effects and therefore has to be estimated during runtime. A common way to estimate the DCO gain is by minimizing the residual error due to phase modulation signal content present in the error feedback signal of the DPLL control loop. This paper derives a simple discrete time, single-rate model of the DCO gain estimation and investigates the behavior and impact on modulation quality for different resource block (RB) allocation scenarios found in LTE uplink transmission. It is shown that the DCO gain estimation is sensitive to modulation signals with contiguous, sparse RB allocation and problems may arise in certain transmission scenarios.

We present a novel concept for a wake-up system based ultra-low power communication protocol for sensor networks. The main application field is monitoring contacts and even tracks of bats in the wild. Our sensor nodes can weigh at most 2 g out of which 1 g remains for the battery. We investigate a novel communication protocol design applicable to these systems and also showing great potentials for other ultra-low power sensor networks. In particular, we investigate the bat to ground communication by combining duty cycling with a multi-stage wake-up receiver. We employ Binary Offset Carrier (BOC) modulated signals that allow to accurately localize and track the bats while transmitting data in parallel. In a first step, we evaluated the conceptual design using a software-defined radio system to demonstrate the feasibility of the protocol design.

This paper contains the development and verification of low noise amplifier stages (LNA) within the framework of a front-end for digital satellite radio diversity receiver operating around 2.3 GHz. First, a low noise high gain LNA is developed to reach the high requirements of satellite radio reception. Therefore a single-ended cascode architecture is chosen. The simulated noise figure is 0.58 dB and the gain is 19.87 dB. Second, a differential stage is designed to fulfill the specification with regards to backward isolation and common-mode rejection. This circuit has a measured gain of 10.15 dB and a backward isolation of -43.24 dB. Furthermore, the two stages are combined by an integrated balun and the overall performance is verified. Due to the good noise performance of the first stage, the overall noise figure is 0.64 dB, the gain is 29.83 dB and the backward isolation is -76.07 dB. All in all the whole circuit has a current consumption of 25.40 mA. Finally the LNA performance is compared with other state-of-the-art LNAs.

So called open loop transmit diversity algorithms for the uplink of UMTS are a topic of recent studies within the 3rd Generation Partnership Project (3GPP). These algorithms use the power control commands of the fast power control mechanism as feedback information to iteratively determine the antenna weights, thus making them compatible with existing networks and procedures. The algorithms presented in literature so far are all designed for a fixed velocity of the mobile terminal. In this paper, evolutionary optimization techniques are employed to design beamsteering algorithms that are adapted to different mobile terminal velocities. These different algorithms are represented by lookup tables that can easily be stored in the terminal. A system is proposed that utilizes information about the current terminal velocity extracted from the downlink signal to always select the most suitable algorithm from a small set of such algorithms. With such a system, the transmit power at the terminal is reduced by 3.3 dB at low mobile velocities of 3 km/h and by 1.9 dB at medium velocities of 30 km/h. This transmit power gain of the proposed system with dynamic adaption of the beamsteering algorithm to the current mobile speed is 0.9 dB higher than with systems with a fixed beamsteering algorithm for all speeds.

This work describes the design of high speed clock recovery circuit for UWB M-sequence based Radio systems in the analog domain to avoid the high power consumed in the analog to digital converters (ADC). The clock recovery circuit depends on two modes, the coarse tuning mode and the fine tuning mode for final locking and tracking. It is illustrated, using this method, that low jitter is achieved while maintaining high acquisition range up to the tuning range of the VCO. The method depends on using a reference M-sequence in the receiver similar to the one used in the transmitter and an analog correlation circuit. The circuits are designed using a low cost 0.25μm 95GHz fmaxSiGe-HBT-BiCMOS process technology consuming an estimated power of 185mW.

Chronic diseases like diabetes mellitus often require a permanent monitoring of vital signs. Especially the use of telemedicine will increase the quality of life for affected patients. Therefore, novel systems are necessary which are able to permanently detect and provide health status information. But these systems must not control patient's life and should work autonomously. For this purpose, intelligent medical implants are well qualified. This work describes a system for wireless power supply and communication with medical implant applications. Monitoring vital signs will create a big amount of data. Therefore, high data rates are necessary provided by high operating frequencies which in turn lead to electromagnetic far-field conditions. In this case, high attenuation losses due to the permittivity of the human body εrhave to be considered. Hence, high frequencies are not suitable for the transfer of energy into the human body. The presented concept is based on two different frequencies for power supply and data transmission. An independent development of both blocks is thereby possible. The power supply operates at a frequency of 13.56 MHz, using inductive coupling. Consequently, the human body does not affect the energy transfer. In contrast, the data transmission is operated at a frequency of the medical implant communication service (MICS) band. The elaborated system consists of a power supply unit, a data transmission unit, and a control unit. The implementation of the power supply and data transmission as well as associated theoretical basics are presented. Performed measurements demonstrate that the realized system is qualified for the use on human beings.

This work discusses the design of a 60ps delay element for UWB analog signals ranging from 0.05 up to 8GHz. The design is implemented using active architecture design which have the advantage of being very compact in area compared to the passive architectures. The proposed architecture is flexible and can be cascaded to have a delay of up to 200ps with a maximum insertion loss of 3dB. The circuit is designed using a low cost 0.25μm 95GHz fmaxSiGe-HBT-BiCMOS process technology consuming a power of 121mW. The estimated consumed area of the circuit is 0.49mm2.

A new aircraft-to-ground telemetry link in C-band, based on Orthogonal Frequency Division Multiplexing (OFDM), is currently being developed for Airbus. In order to parameterize this link adequately, information about the propagation channel is indispensable, in particular in terms of delay spread and Doppler spread. In order to identify these characteristics, a novel easy-to-use channel sounder was developed and successfully applied in multiple flight campaigns. With the channel sounding results, three typical environments could be clearly distinguished according to their specific charateristics: Parking & taxiing, take-off & landing and en-route. The measurement results are directly applicable as constant coefficients for tapped-delay line modeling. In contrast, classical approaches apply coefficients of stochastical nature, modeled as random variables. However, for a specific communication scenario, which we face here, the proposed approach yields much more accuracy and reliability, as it represents the exact real-world channels.

Electric driven vehicles become more and more important in today's mobile world. In addition to all its benefits, this technology has some drawbacks. Due to the electrical drive system, we measure higher voltages and higher currents. This is the reason why we get more electromagnetic interference (EMI) in the electric vehicle (EV). The highest requirements regarding EMI result from broadcast reception systems. The conventional approach of noise suppression with passive, active or hybrid filter structures and shielding increases the costs and the weight of the vehicle. In this paper a concept is presented, where the expensive shielding is replaced or supported by digital signal processing in the tuner. The active noise suppression can be supported by additional field probes. Therefore, the tuner can receive more information about the interferers. This principle works like the well-known "Active Noise Cancelling" (ANC). The algorithms have to be developed individually for each broadcast standard and are derived in this presentation for FM, AM and DVB T. Simulation results of the new approach demonstrate dramatic performance improvement in an EMI burdened car environment.

Automatic recognition of communication standards is a crucial task, if universal interoperability between different communication systems is claimed. A gateway performing the recognition task can be used to interconnect heterogeneous systems with different and incompatible protocol waveforms. This paper proposes an algorithm for the automatic recognition of various communication standards used for wireless smart home networks in the European 868 MHz Short-Range Device frequency band. Relevant statistical key features are extracted from the received signal and the recognition is based on threshold comparison. The algorithm is appropriate for the implementation in low-complexity embedded systems and works over a wide range of signal-to-noise ratios (SNR).

Wireless communication systems used for home automation applications in Europe suffer from the recurring standardization problem. Devices from different manufacturers often use different and incompatible protocol waveforms for communication. In this paper, we present the development and the implementation of a feature-based automatic classification algorithm for communication standards that are commonly used in the European 868 MHz short range device (SRD) frequency band, that can help to overcome this problem. The received signal is initially preprocessed and then fed to a feature extraction unit that calculates statistical parameters from the signal. Those features are then used by a classifier that is based on a simple binary decision tree. The performance of the algorithm is verified via Monte-Carlo simulation and compared to the bit error rates of the considered communication standards as a function of the signal-to-noise ratio. Finally, the algorithm is implemented in a software defined radio (SDR) platform and the measurement results are compared to the simulation-based success rates.

In smart grid applications, a reliable communication infrastructure is crucial to allow smart metering and demand side management. If different utility meters (e.g. electricity, gas and water meters) and home automation systems use different and incompatible protocol waveforms for wireless communication, such an infrastructure is hardly realizable using state of the art communication technology. Thus, a cognitive gateway is required that is able to automatically recognize the protocol waveform used by an unknown transmitter and to translate the massage into the waveform of the addressed receiver. This paper proposes a decision-theoretic algorithm for the automatic classification of wireless communication standards used for smart grid applications in the European 868 to 870 MHz band. The algorithm is adequate for the implementation in realtime embedded systems and works over a wide range of signal-to-noise ratios.

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. Search and Rescue with modern localization techniques consequently attracts attention from scientific and industrial sides. This paper introduces one part of the I-LOV project, endorsed by the Federal Ministry of Education and Research Germany. Here partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. Future developments in the area of mobile phone detection by field intensity measurements will be addressed in this paper.

Ultra-wideband (UWB) techniques are recently targeted as a broadband short range solution for in-flight-entertainment (IFE) systems. Despite the in-cabin channel can be considered as an indoor channel, under the current aviation regulations, and due to the usual metal cabins and cylindrical shapes, these scenarios are particular for wireless applications. In this paper is presented an experimental characterization of the UWB channel within an Airbus 319 aircraft cabin based on a real-time multiple-input-multiple-output (MIMO) UWB channel sounder. Here, the delay spread and coherent bandwidth have been calculated for different antennas configurations and distances. Besides, the in-cabin path-loss exponent has been calculated based on an extensively amount of data. Moreover, dynamic range metrics have been introduced for channel analysis and performance comparisons along the cabin.

Local positioning systems significantly enhance the value of wireless sensor networks (WSN). This paper presents an integrated synthesizer for localization using frequency modulated continuous wave (FMCW) radar. The synthesizer is based on a fractional-n phase-locked loop (PLL) architecture. All components of the PLL are carefully designed with respect to their power consumption, and the digital parts are implemented in current-mode logic (CML). The complete synthesizer was manufactured in a 0.18 mum SiGe BiCMOS process from IBM, and it consumes only 100 mW, achieves a phase noise better than -117 dBc/Hz and has a silicon area of 1.15 mm2. Due to its high integration level and its optimized design, the synthesizer achieves low power consumption and low phase noise that make it suitable for precise localization in mobile sensor nodes. Localization measurements in indoor environments with multi- path propagation showed mean distance errors about 10 cm.

Quality of Service (QoS) is a prevalent issue in communication systems, but an often neglected aspect of local positioning. In this paper, we present a QoS architecture for the high-accuracy local positioning system RESOLUTION. Different backend configurations of this system are compared in terms of impact on accuracy and latency of the system. Quality metrics relevant to local positioning requirements are defined and tested with several protocol and algorithmic options by means of simulations. Results indicate parameter tradeoffs which call for optimization of the backend architecture for specific deployment scenarios. These insights are easy to transfer to any positioning system which has to deal with channel contention situations.

With the growing demand for wireless communication systems, wireless concepts for the data exchange in time variant ad-hoc networks become more and more interesting. In order to describe and thus assess the mobile radio channels in such networks, simulations are required. The main aspect is the time-variance of the channel impulse response and the detailed modeling of large scenarios. This paper discusses the demands for a model to describe the radio channel in time variant environments and presents an appropriate Ray Tracing approach. A new concept is introduced to substitute complex polygonal objects by several radar cross sections (RCS). The performance of the Ray Tracing algorithm is confirmed by a comparison from predicted to measured channel characteristics.

The hierarchical substrate coupling simulation tool Sub-CALM offers the opportunity to estimate substrate coupling on floorplan level. A novel approach for modeling well and SOI structures in a boundary element description is introduced. Several acceleration techniques like precalculated macromodels and sophisticated preconditioning algorithms are presented which are applied to an O(n)-conjugate-gradient Poisson solver in order to be able to process large full-chip layouts during floorplanning.

In this work we investigate the meaning of decision feedback equalization for a single carrier system with frequency domain equalization (SC/FDE) in an overall system approach, based on the parameters of the IEEE 802.11a standard. The concept of SC/FDE allows an advantageous combination of feed forward frequency domain equalization and feed back equalization in the time domain, that combines low signal processing complexity and powerful equalization. Although the concept of decision feedback equalization (DFE) is a well known and developed theory, this nonlinear equalization is rarely investigated in an overall system approach. Based on that the possible performance gain will be characterized under the constraints of channel characteristics, error propagation, higher order modulation schemes and channel coding. It will be demonstrated that these elements have significant influence on the possible performance of DFE and may reduce the propagated high performance gain.

Although nonlinear equalizer structures seem to be a well developed theory, these equalizer structures are rarely investigated in an overall system approach. It is the topic of this paper to point out that it is inevitable to characterize decision feedback equalizer structures (DFE) in the context of channel characteristics, error propagation and implementation effort before talking of performance gain compared to linear equalizer structures. In particular DFE is characterized in the context of antenna diversity and channel coding as these techniques are indispensable for future high rate wireless communications systems. Only this overall system approach allows a reliable statement concerning the expected performance gain due to different equalizer strategies. The simulation results in this work are based on a single carrier system with frequency domain equalization (SC/FDE), as this concept allows an advantageous combination of feedforward frequency domain equalization and feedback equalization in the time domain, combining low signal processing complexity and powerful equalization. The simulation parameters are adapted to the parameters of the IEEE 802.11a standard.

In this work we investigate the effect of convolutional coding, interleaving and Viterbi decoding, as they are used for OFDM (orthogonal frequency division multiplexing) in the IEEE 802.11a standard, for a single carrier system with frequency domain equalization (SC/FDE). We will characterize the effect of decision length (maximal length of the trellis) and code rate in terms of bit error behavior, reliability of soft decisions and implementation effort for the classical Viterbi algorithm as well as for the soft output Viterbi algorithm (SOVA). The (coding) parameters of the simulated system are adapted to the IEEE 802.1 Ia standard for WLAN applications. In detail we will elaborate on the advantages of pilot symbols, that are multiplexed into the data stream as a method to reduce the necessary decision length as well as to reduce the implementation effort and to improve the SOVA output. It will be demonstrated that the use of pilot symbols shows significant advantages that dominate the disadvantages.

Single carrier transmission with frequency domain equalization (SC/FDE) has been shown to be a promising alternative to orthogonal frequency division multiplexing (OFDM) systems for wireless LANs. In this work we add time domain turbo decision feedback equalization to conventional SC/FDE for block transmission with cyclic prefix. The proposed scheme achieves the potential of ideal decision feedback equalization. Simulation results show a considerable performance increase for highly frequency selective radio channels given in W-LAN environments.

This paper presents a novel substrate coupling simulation tool that is well suited to floorplanning of large mixed-signal IC designs. The IC layout may consist of several subcircuits, hence a hierarchical design flow, which is usually used for IC circuit design and layout, is supported. Coupling data modelling the substrate inside subcircuits are precalculated and subsequently used during floorplanning, leading to shorter simulation time. In addition, the impedance model of the power grid is considered as well making it possible to provide estimation results of substrate coupling quickly after only one simulation step. The approach is verified by experimental results in 0.13 /spl mu/m CMOS and 0.25 /spl mu/m BiCMOS technologies.

We investigate the use of a known symbol sequence - a so-called unique word (UW) - instead of the well-known cyclic prefix (as it is used in OFDM, orthogonal frequency division multiplexing, systems) for a single carrier system with frequency domain equalization (SC/FDE). The considered SC/FDE system is similar to the one proposed in the IEEE 802.16.3c target group. It is shown that the UW fulfils the theorem of cyclic convolution required for efficient implementation of the SC/FDE structure. We elaborate on the advantages that result for equalization, channel estimation, and synchronisation. Compared to the advantages, the disadvantages in terms of BER behaviour and bandwidth efficiency are rather modest.

A high data-rate wideband chirp spread spectrum system for indoor communication is proposed. The use of chirp signals with the well known pulse compression technique makes the system extremely robust and therefore suitable for applications in an industrial environment. By using /spl pi//4 DQPSK modulation, overlapping chirp signals, and optimized chirp signal design we get data rates up to 70 Mbps. There is no need for sophisticated digital signal processing due to the use of surface acoustic wave (SAW) filters for the generation and filtering of the chirp signals. Production tolerances, temperature drift, and other system imperfections are shown to be either negligible or can easily be tracked. Simulation results reveal that the limiting factor for the data rate is intersymbol interference caused by multipath propagation.

A low-power fully-integrated type-2 4th-order 1.7 GHz CMOS frequency synthesizer for DCS-1800 application is designed and simulated in a 0.25 /spl mu/m process technology. The frequency switching is achieved using a novel architecture exploiting a direct digital synthesis (DDS) device as the frequency reference. The new topology significantly lowers the undesired sideband power due to divider ratio switching by directly shifting the frequency of the DDS reference. The frequency synthesizer (excluding the DDS device) dissipates only 9 mW of power from a 2 V power supply. It employs a fast-switching novel charge pump circuit and a low-noise fully-integrated differential LC voltage controlled oscillator using on-chip spiral inductors and accumulation-mode capacitors to meet the requirements of a DCS-1800 system. A detailed analysis of the phase noise in the 4th order loop is presented.

The main applications of surface acoustic wave (SAW) convolvers have previously been military and have required high processing gain values. Rather complex hybrid fabrication technologies have to be employed needing large packages and resulting in expensive devices. Applications in radio frequency (RF) consumer communications use relatively short code sequences. For these systems, low-cost SAW convolvers with moderate time-bandwidth products on the order of a few hundred have many interesting features. To meet the demands for low price and high reliability, precise reproducible designs and economic mass production of the devices are indispensable. The authors report on the design and performance of a small and compact prototype SAW convolver. Input center frequency, integration time and time-bandwidth product are 350 MHz, 3 /spl mu/s and 150, respectively.