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Inspired by recent promotions of wireless location services and applications, this paper develops a simple model for detecting a mobile caller location with low implementation complexity and promising accuracy. The model that is described in this paper employs the geometrical transformation method with single propagation delay measurement. Depending on the number of available surrounding base transceiver stations (BTS5), a set of the pseudodistances and pseudodistance differences is provided through the geometrical distances between the home and multiple foreign BTSs, which is called the geometrical transformation method. Accordingly, the mobile caller location can be detected using the circular location technique and the hyperbolic location technique. The major benefit of the proposed model is that during a call to detect the mobile caller's location, the use of geometrical transformation allows us to overcome the location handover problem. A forcing handover in a Global System for Mobile Communications (GSM) network or a three-way soft handover in a Universal Mobile Telecommunications System (UMTS) network, for example, occurs when detecting the location when a standard model that is based on the measurement of the propagation delay is utilized. Comparing the standard model with the proposed model, the former needs at least three propagation delays that were simultaneously measured from at least three BTSs, whereas the latter needs only a single propagation delay that was measured from the home BTS. Moreover, in the case where we do not have a priori information of a non-line-of-sight (NLOS) error, a deterministic parameter that is related to the propagation delay is defined. This parameter is shown as limited a priori information for calibrating the coarse resolution in the proposed location model, which is caused by the NLOS error. To have significant findings, we conduct a practical experiment in an urban environment based on a 1.8-GHz commercial cellular network. In the five-BTS case where the location error is less than 300 m, the probability of location error that the proposed model with a bit period of 1/2 achieved is greater than 0.85. Although the performance of the proposed location model does not satisfy the U.S. Federal Communications Commission Enhanced 911 (FCC E-911) requirements, it is a good solution for the deployment of wireless location services and applications. [ABSTRACT FROM AUTHOR]

Tests for the wide-sense stationarity (WSS) of multivariate random processes are developed and applied to measured multiple-input--multiple-output (MIMO) radio channel responses. Evolutionary spectral density functions are used to estimate the time-dependent power spectral density, and analysis of variance procedures are applied to determine whether the first and second moments of the data series exhibit statistically significant changes over short intervals. It is found that while the assumption of WSS is met in 40%-70% of half-second intervals for a single element at the transmitter and receiver, only 2%-12% of intervals with two elements at the transmitter and receiver are jointly WSS; furthermore, the occurrence of non-WSS intervals is not dependent on the antenna separation. The analyses also show that WSS intervals are interspersed with long non-WSS intervals. [ABSTRACT FROM AUTHOR]

This paper presents the results of a measurement campaign conducted in the winter of 2002 around the city of Munich in southern Germany. The primary goal was to evaluate the link performance of the land mobile satellite channel at Ku-band and to characterize the temporal behavior of the channel to help in the evaluation of different fade mitigation techniques for future mobile satellite systems that aim at employing this frequency band. To achieve this objective, first- and second-order channel statistics will be presented, the outage probability of the channel analyzed, and a Markov-chain-based narrowband channel model proposed. [ABSTRACT FROM AUTHOR]

In this paper, the validity of Recommendation ITU-R P.1546 in a short-range terrestrial environment is analyzed. Its three versions (P.1546, P.1546-1, and P.1546-2) are compared against simple models and evaluated using measurement results that were obtained by utilizing the pilot signal of a commercial code-division multiple-access mobile telephone network. Measurement results show that P.1546-2, on average, underestimates the field strength by more than 10 dB for typical Australian rural areas. However, it improves the error standard deviation compared to previous versions. The causes of these effects and the suggestions for further development of the Recommendation are discussed and evaluated. [ABSTRACT FROM AUTHOR]

Propagation path losses affecting intervehicle communication (IVC) at 60 GHz are presented. In order to examine the radio-propagation characteristics in the IVC system, in the first stage of our investigation, we have carried out propagation tests between two vehicles communicating in a line-of-sight (LOS) situation at fixed positions on a smooth surface paved with asphalt, which is the normal communication condition. Furthermore, the non-LOS (NLOS) situation with up to three intermediate vehicles, which can cause an obstruction, has been conducted. To construct path-loss models in NLOS cases, the uniform theory of diffraction technique was applied to the calculation of waves propagating through the intermediate vehicles. The propagation path models were derived from the measured results. In the second stage, a path-loss prediction formula was derived by statistically processing the data that had been calculated using the propagation path model. The propagation tests between the vehicles in motion confirm that the path-loss prediction formula is very useful when the communicating vehicles are moving, and it is therefore suitable for designing the cells that form the IVC. [ABSTRACT FROM AUTHOR]

A propagation model is needed to evaluate the performance of handover in mobile-communication systems. Generally, the received signal level from base stations (BSs) is calculated assuming path loss, and a lognormal (shadow)-fading model is used for evaluating intercell handover. The lognormal fading was assumed to be uncorrelated between cells. However, since the correlation between sectors is not clarified, an appropriate shadow-fading model to evaluate intersector handover has not yet been proposed. To obtain shadow-fading characteristics between neighboring sectors, the change in signal level and the direction of arrival of incoming waves at a BS must be clarified. This paper proposes a simple model of incoming waves to evaluate the performance of intersector handover. The validity of the proposed model is confirmed by comparing the difference between signal levels in BS sectors that are calculated using the proposed model and the measured power azimuth spectrum. [ABSTRACT FROM AUTHOR]

This paper covers some of the work carried out in the planning of the Global System for Mobile Communication for Railway (GSM-R) of the tunnels on the new high-speed trains in Spain. Solutions based on distributed antenna systems have been tested by installing several 900-MHz transmitters inside and outside of a 4000-m tunnel and measuring the propagation indifferent conditions. The measurements have been used to model the effects of tunnel propagation, including curves, trains passing from the outside to the inside, and the effect of two trains passing inside the tunnel. All cases have been tested by comparing solutions using isofrequency and multifrequency distributed transmitters inside the tunnel. The improvements of signal-to-noise ratio and the reduction of the blocking effects of two trains passing have demonstrated the advantages of using isofrequency distributed antenna systems in tunnels. Finally, a complete propagation model combining both modal analysis and ray tracing has been applied to predict the propagation loss inside and outside these tunnels, and results have been compared with the measurements. The model has proven to be very useful for radio planning in new railway networks. [ABSTRACT FROM AUTHOR]

This paper concerns the measurement-based comparison of urban microcellular mobile radio channel characteristics at 1.9 GHz and a higher frequency, i.e., 5.8 GHz, where future wireless systems could operate. Characteristics that are reported include transmission loss, root-mean-square delay spread, frequency correlation, and envelope fading statistics. Conclusions are drawn concerning whether significant differences in the performance of mobile radio links operating under the same signal-to-noise ratio conditions in the two bands would be expected in the area where the measurements were made. [ABSTRACT FROM AUTHOR]

Stochastic properties of the binary channel that describe the successes and failures of the transmission of a modulated signal over a time-correlated flat-fading channel are considered for investigation. This analysis is employed to develop κth-order Markov models for such a bunt channel. The order of the Markov model that generates accurate analytical models is estimated for a broad range of fading environments. The parameterization and accuracy of an important class of hidden Markov models, known as the Gilbert-Elliott channel (GEC), are also investigated. Fading rates are identified in which the κth-order Markov model and the GEC model approximate the fading channel with similar accuracy. The latter model is useful for approximating slowly fading processes, since it provides a more compact parameterization. [ABSTRACT FROM AUTHOR]

Presents information on a study which described the development and implementation of a propagation model for urban microcells in mobile communication systems. Application scenario of the propagation model; Assessment of the propagation model; Conclusion.

Presents information on a study which described a propagation prediction tool developed to facilitate the path loss computation in urban environments. Significance of accurate prediction of signal propagation characteristics in urban mobile radio systems; Mathematical formulation used for the electric field representation; Simulation results and tool validation; Conclusion.

Presents information on a study which investigated the propagation mechanisms reflection and diffraction of millimeter waves at realistic road surfaces and geometries. Spectacular reflections in mobile-to-mobile scenarios; Obstruction of the line of sight by intermediate vehicles; Diffraction around road crests; Conclusion.

Presents information on a study which examined design issues for a microcellular system that can accommodate the heavy traffic load forecast for mature systems. Performance of microcellular systems in residential and commercial environments; Generation of diamond reuse pattern for microcells; Effect of cochannel microcells on microcellular system design; Conclusion.

Describes the main statistical characteristics of the propagation channel of large transverse dimensions, with the carrier frequency being near 2 GHz. Systems that have to be developed in order to ensure radio coverage of long tunnels; Details on the theoretical and experimental results on the fading distribution.

Presents a study which focused on mobile and personal communications while highlighting radio wave propagation in railway tunnels. Details on empty tunnel radio wave propagation; Characterization of radio wave propagation in loaded train tunnels; Method used to conduct the study; Results of the study.