Juan Pontes

Simulation and Evaluation of Car-to-Car Communication Channels in Urban Intersection Scenarios

This paper evaluates multiple antenna systems in realistic Car-to-Car (C2C) communication channels for urban intersection scenarios. With a three-dimensional ray-tracing simulation tool the channel characteristics are determined for various antenna positions and numbers of antennas. The results clearly show the advantage of multiple antenna systems. Suitable antenna positions are determinedthatallowtheoptimizationofthe channel capacity ( )However, in spite of the benefits of route specific infor- mation, the amount of data to be processed and transmitted presents a great challenge. Other road users as well as the surroundings influence the channel in a complex manner. It follows that a detailed knowledge about the inter-vehicle trans- mission channel is necessary for the design and optimization

Virtual Drives in Vehicular Communication

The fast and economical prototype development of (vehicular) antenna systems requires the employment of feasible simulators. This article describes such a simulator for vehicular communications. The channel model used is based on stochastically or deterministically generated 3-D environments that include a realistic traffic model. The wave propagation is calculated with a fully polarimetric ray tracing tool. In addition, an antenna synthesis method for predefined time-variant communication scenarios has been proposed. The major emphasis has been put on MIMO systems, but in general, the algorithm can be employed for multiple-element as well as single-element antenna systems.

Investigation on Antenna Systems for Car-to-Car Communication

This paper introduces a novel method for the investigation of antenna systems in Car-to-Car communication channels. With a three-dimensional ray-tracing simulation tool the channel characteristics are determined for various antenna positions and numbers of antennas in realistic car-to-car communication channels for urban intersection scenarios. Then an antenna synthesis method is used to determine the optimum current distributions for each subchannel, i.e. the optimum radiation patterns, in order to investigate the communication limits of those channels. As result it is seen, that for this type of scenarios antenna placement is decisive in the system performance. Furthermore, it is shown that under the studied configuration, multiplexing effects could not be exploited and that placement of the antennas below the car is more robust toward scenario changes.

Capacity maximizing MIMO antenna design for Car-to-car communication

The handling of the radio channel is an important aspect that determines the working capability of a mobile communication system. Since the channel behavior is influenced by the environment, which leads to a different behavior in different environment, the antenna design (synthesis) becomes environment dependent (time-variant) as well. In this paper, a capacity maximizing approach to design antenna systems for time-variant channels is presented. Real world constraints such a space, transmit power, the number and arrangement of the antennas are taken into account. The theory of this approach and an optimization of a 2×2 MIMO system for Car-to-car (C2C) communication using measured antennas patter and simulated in typical C2C scenarios are shown.

Modal Network Model for MIMO Antenna in-System Optimization

The analysis of MIMO systems is described with the aid of a novel modal network model. For this purpose the capacity performance of typical base station and mobile station antennas in a simulated macro-cellular scenario with varying antenna inter element spacings and antenna rotation will be studied. The model is based on the modal description of typical receiving and transmitting antennas. In this manner a significant simulation time reduction is achieved which allows for faster analysis and optimization. To prove this the effects of both the mobile and base station antennas are investigated. Moreover, for the more restrictive case of base station antennas, a fully modal descriptive model is proven to yield very similar results as those from measured commercial antennas. It is found that the modal approach improves simulation speed without loss of accuracy or generality. Simulations are done for the city of Karlsruhe with a three-dimensional Ray-tracing tool.

Dielectric Resonator Antennas for Polarization Diversity in Base Station Array Applications

Dielectric resonator antennas (DRA) are mostly investigated for frequencies above approx. 5 GHz, but in this paper they are suggested for use in the mobile communication standard UMTS (1.92 -2.17 GHz) base stations, because they can provide a denser aperture since they can be drastically reduced in size through proper selection of the materials dielectric constant. In this paper the main aspect will be the investigation of dual polarized resonators and the buildup of arrays. The goal is to provide a solution which can compete with the commercial market and additionally offer new possibilities.

BER Simulations of a UWB Spatial Multiplexing System Using an Extended Ray-Tracing Approach

This letter investigates the performance of a previously published hybrid channel model, where a standard ray-tracing model is combined with a statistical approach for simulation of dense multipath components. In particular, this hybrid method is compared against measurements and conventional ray-tracing simulations with respect to path loss, delay spread, and bit error rates of a 22 multiple-input-multiple output multiband OFDM (MIMO-MB-OFDM) system. It is seen that the hybrid method outperforms the conventional ray-tracing model, delivering very realistic performance estimates.

Evaluation and Optimization of CDMA System Performance in Macrocell Environments based on Antenna Radiation Pattern

In this paper it is demonstrated for the first time that for the specific case of base station antennas in macrocell environments it is possible to use a simple propagation model for antenna performance evaluation and design with similar results to those of computationally more complicated simulators. For this purpose, a set of criteria is defined, which, when fulfilled, is shown to assure sufficient coverage, to minimize interference and permit handover

Modulation and Detection

In this chapter, we present a number of topics surrounding modulation and demodulation. We begin by introducing system-level block diagrams of AM and FM/PM modulators and demodulators, and explaining their respective principles of operation. In particular, under the topic of AM Modulator/Demodulator, we introduce the full carrier modulator, the single sideband suppressed carrier modulator, the double sideband suppressed carrier modulator, the envelope detector, and the synchronous detector. Under the topic of FM and PM Modulator/Demodulator, we introduce the VCO as FM modulator, the indirect FM modulator, the PM modulator, the balanced discriminator FM demodulator, the quadrature FM detector, the PLL-based FM detector, the zero-crossing FM detector, and the PM demodulator. Then, under the topic of digital modulation, we introduce the concepts of Nyquist Limit, data rate, Shannon Limit, information capacity, and bandwidth efficiency, as well as specific modulation schemes, such as, binary modulation, amplitude-shift keying (BASK), frequency-shift keying (BFSK), and phase-shift keying (BPSK), differential binary phase-shift keying (DBPSK), quadrature phase-shift keying (QPSK), π/4 shifted QPSK, minimum shift keying (MSK), M-ary quadrature amplitude modulation (QAM), orthogonal frequency division multiplexing (OFDM), direct sequence spread spectrum (DS/SS), and frequency hopping spread spectrum (FH/SS). We also introduce the geometric representation of digital modulation schemes and the complex envelope form of a modulation signal.

Radio Channel Fundamentals and Antennas

In this chapter, we begin by discussing the fundamentals of the radio channel. Typical Radio Transmitter and Receiver block diagrams are reviewed, together with the components of a wireless communications system. Then, we turn to addressing the phenomenon of wave propagation, in particular, Multi-Path Propagation, Free-Space, and Path Loss. The relationship between power and electric field is elucidated, the Effective Isotropic Radiated Power is defined, and the measured received electric field is related to the received power. Then, the various models invoked in calculating the effects of propagation are presented. These include: Reflection, in particular, the conditions of: (1) Two Half-Spaces: Dielectrics; (2) Two Half-Spaces: Metals; (3) Two Half-Spaces: Multi-Layer Structures; and (4) Two-Ray Ground Model. This is followed by a discussion of Diffraction, in particular, from a Knife-Edge. We conclude this discussion with the topics of Scattering, and Reflection in the Troposphere. The chapter is concluded with a discussion of antenna parameters, in particular: (1) Efficiency; (2) Effective Area; (3) Gain; and (4) Directivity.