The COST259 Directional Channel Model-Part I: Overview and Methodology
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paper_title: A space-time correlation model for multielement antenna systems in mobile fading channels

paper_content:

Analysis and design of multielement antenna systems in mobile fading channels require a model for the space-time cross correlation among the links of the underlying multiple-input multiple-output (MIMO) channel. In this paper, we propose a general space-time cross-correlation function for mobile frequency nonselective Rice fading MIMO channels, in which various parameters of interest such as the angle spreads at the base station and the user, the distance between the base station and the user, mean directions of the signal arrivals, array configurations, and Doppler spread are all taken into account. The new space-time cross-correlation function includes all the relevant parameters of the MIMO fading channel in a clean compact form, suitable for both mathematical analysis and numerical calculations/simulations. It also covers many known correlation models as special cases. We demonstrate the utility of the new space-time correlation model by clarifying the limitations of a widely accepted correlation model for MIMO fading channels. As another application, we quantify the impact of nonisotropic scattering around the user, on the capacity of a MIMO fading channel.
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paper_title: Spatial channel characteristics in outdoor environments and their impact on BS antenna system performance

paper_content:

This paper present measurement results obtained with a testbed equipped with an array antenna. The investigations focus on the power azimuth spectrum of the channel in urban and rural areas, for various base station antenna heights. The power azimuth spectrum is well modeled with a Laplacian function. The local azimuth spread is found to range from 1/spl deg/ to 25/spl deg/ depending on the environment and antenna height. The azimuth spread significantly increases as the antenna height is reduced. An analytical expression for the spatial correlation function is derived based on the Laplacian model. Finally, the power azimuth spectrums impact on a conventional beamformer ability to suppress interfering users is investigated.
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paper_title: The GSM System for Mobile Communications

paper_content:

From the Publisher: ::: This book is out-of-print, and a new second edition will be released by the end of 2002. ::: The digital standard known as the Global System for Mobile (GSM) has captured a large share of the global cellular market. This book aims to bridge the gap between a reader?s basic knowledge of telecommunications and the complexities of the 5000-page GSM technical specification. It describes the system as a whole, covering all aspects of the standard, including mobile stations, switching equipment, the radio interface, infrastructure, transmission methods, and signaling protocols. System architects involved in the design of personal communications systems will find the book to be a complete description of the GSM communications system. It also may serve as a general introduction to digital cellular systems.
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paper_title: Backward compatibility of the COST259 directional channel model

paper_content:

We consider the COST259 directional channel model (DCM) in relation to other existing channel models. The COST259 DCM is a general model for the mobile radio channel that includes narrowband power (field strength), power delay profiles, and directions of arrival. For comparison purposes, it is desirable that the channel models forming the basis of earlier simulations are contained as special cases in the COST259 DCM. We show how a mixed stochastic/deterministic approach allows the GSM wideband models to be kept as special cases of COST259 DCM while still including new measurement results. The mean received powers agree with M. Hata's model (see IEEE Trans. on VT, vol.29, p.317-25, 1980) when proper averaging over stochastic variables is done. Finally, the shadowing distribution of the narrowband power is shown to agree with M. Gudmundson's model (see Electronic Letters, vol.27, no.23, p.2145-6,1991).
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paper_title: Spatial channel model and measurements for IMT-2000 systems

paper_content:

This paper presents a spatial channel model for IMT-2000 systems as well as measurement results for 1.2 MHz wide wireless channels using an eight element linear array at two different frequencies. The spatial channel model is a spatial extension of the commonly known IMT-2000 temporal (i.e., delay profile) model. The measurement results are used to characterize the spatial aspects of the wireless channel and are used to verify the model.
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paper_title: Statistical modeling of small-scale fading in directional radio channels

paper_content:

After a review of the known description of time-variant channels by means of system and correlation functions, a consistent extension of this description to directional time-variant channels is described. This extension allows a clear distinction between time- and space-variant effects in directional mobile radio channels. The major intention of the described directional extension however is the derivation of a statistical modeling approach for small-scale fading effects in time-variant wideband directional channels, which can be regarded as a consistent extension of the well established Rayleigh or Rice-fading approach for nondirectional time-variant narrowband channels. The approach, which is based on the time and aperture-variant transfer function, appears to be preferable to the frequently used statistical modeling of the time-variant angle-resolved impulse response for several reasons. The major advantage is that the approach can cope with the demand for a great number of superimposing components as the basis for statistical modeling. The correlation between adjacent values is proposed to be achieved by filtering with appropriate directional scattering functions. The description of the modeling approach, as done in the present paper, is intended to be general and universal; for the application on certain channel types statistical distribution functions and parameters to be used with the approach can readily be determined from appropriate measurements.
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paper_title: Diffuse channel model and experimental results for array antennas in mobile environments

paper_content:

A wide-band spatial model of the mobile channel has been developed. The model allows the inclusion of array antennas at the base station. The diffuse scattering is modeled using dense discrete scatterers. An algebraic power decay is used for the path loss to the scatterers of the environment and to the mobile. Results from the model are compared with experimental results obtained at 1800 MHz. The parameters that are used are delay spread, power window, and angular spread of incident power. The model elucidates the general diffuse background scattering in a rural and an urban environment. It can be extended with inclusion of spatial specular scatterers where appropriate.
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paper_title: Mobile Communications Engineering

paper_content:

From the Publisher: ::: This authoritative work was written to be the bible for advanced commercial mobile phone systems and military mobile communications systems. Emphasizing how to study and analyze mobile communications problems,the book thoroughly explains how to design a mobile radio communication system. Introductory material describes existing systems,bridging the gap for students unfamiliar with the field. The characteristics of mobile radio signals are covered,applying statistical communication theory to propagation and received signal characteristics. Functional design is introduced,and a discussion of system performance included to explain how to evaluate a new system. The author uses both theory and experiments to support practical design and development of systems in the microwave frequency ranges configured for high-capacity mobile telephone and data communications.
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paper_title: A wideband directional channel model for UMTS microcells

paper_content:

The development of a planar wideband directional channel model applicable to UMTS microcells is addressed. The model, a statistical one based on geometrical considerations, is implemented and simulated, its assessment being based on global parameters of channel impulse responses obtained from measurement results. Exemplifying results for the directional channel impulse response are depicted for streets based on the city of Lisbon. For longer distances, system performance improvement is expected when using adaptive antennas.
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paper_title: A geometrically based model for line-of-sight multipath radio channels

paper_content:

This paper provides a geometrically based model for single bounce multipath components in line-of-sight (LOS) microcell radiowave propagation channels. The model characterizes the excess delay, direction-of-arrival, and received power of multipath components and is particular useful for microcell and PCS systems with low transmitter and receiver antenna heights. The model includes analytical expressions for the probability density functions for all critical channel parameters and is thus useful for analytical purposes. The model is also useful for simulating both wideband and narrowband systems and in particular the model has been used extensively in a study of code division multiple access (CDMA) cellular radio systems employing adaptive antennas and switched beam systems at the base station.
---
paper_title: Wideband CDMA for third generation mobile communications

paper_content:

Basic principles of DS-CDMA applications radio operating environments and their impact into system design system design aspects a novel wieband CDMA radio interface typical wideband CDMA radio interfaces performance analysis time division duplex (TDD) DS-CDMA hierarchical cell structures implementation aspects radio nerwork planning and deployment network aspects comparison to TDMA and other 3rd generation radio interface proposals future developments.
---
paper_title: Indoor wideband time/angle of arrival multipath propagation results

paper_content:

Most current indoor propagation experiments measure the time of arrival of characteristics of multipath reflections without regard to the angle of arrival. Because of the increasing number of systems that are used indoors and which use multiple antenna systems to combat multipath interference, a need exists for indoor propagation data which takes the angle of arrival into account. A system is described which was used to collect simultaneous time and angle of arrival data in two indoor environments. A total of 65 data sets were taken in two buildings of different construction. The (7 GHz) data confirmed the temporal model proposed by Saleh and Valenzuela (1987), and showed a unique clustering pattern in angle, which consisted of clusters uniformly distributed in angle, with members of the clusters following a Laplacian distribution.
---
paper_title: A Statistical Model for Indoor Multipath Propagation

paper_content:

The results of indoor multipath propagation measurements using 10 ns, 1.5 GHz, radarlike pulses are presented for a medium-size office building. The observed channel was very slowly time varying, with the delay spread extending over a range up to about 200 ns and rms values of up to about 50 ns. The attenuation varied over a 60 dB dynamic range. A simple statistical multipath model of the indoor radio channel is also presented, which fits our measurements well, and more importantly, appears to be extendable to other buildings. With this model, the received signal rays arrive in clusters. The rays have independent uniform phases, and independent Rayleigh amplitudes with variances that decay exponentially with cluster and ray delays. The clusters, and the rays within the cluster, form Poisson arrival processes with different, but fixed, rates. The clusters are formed by the building superstructure, while the individual rays are formed by objects in the vicinities of the transmitter and the receiver.
---
paper_title: Characterization of Randomly Time-Variant Linear Channels

paper_content:

This paper is concerned with various aspects of the characterization of randomly time-variant linear channels. At the outset it is demonstrated that time-varying linear channels (or filters) may be characterized in an interesting symmetrical manner in time and frequency variables by arranging system functions in (timefrequency) dual pairs. Following this a statistical characterization of randomly time-variant linear channels is carried out in terms of correlation functions for the various system functions. These results are specialized by considering three classes of practically interesting channels. These are the wide-sense stationary (WSS) channel, the uncorrelated scattering (US) channel, and the wide-sense stationary uncorrelated scattering (WSSUS) channel. The WSS and US channels are shown to be (time-frequency) duals. Previous discussions of channel correlation functions and their relationships have dealt exclusively with the WSSUS channel. The point of view presented here of dealing with the dually related system functions and starting with the unrestricted linear channels is considerably more general and places in proper perspective previous results on the WSSUS channel. Some attention is given to the problem of characterizing radio channels. A model called the Quasi-WSSUS channel is presented to model the behavior of such channels. All real-life channels and signals have an essentially finite number of degrees of freedom due to restrictions on time duration and bandwidth. This fact may be used to derive useful canonical channel models with the aid of sampling theorems and power series expansions. Several new canonical channel models are derived in this paper, some of which are dual to those of Kailath.
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paper_title: A new stochastic spatio-temporal propagation model (SSTPM) for mobile communications with antenna arrays

paper_content:

In order to evaluate the performance of third-generation mobile communication systems, radio channel models are required. The models should be capable of handling nonstationary scenarios with dynamic evolution of multipath. In this context and due to the introduction of advanced antenna systems to exploit the spatial domain, a further expansion is needed in order to include the nonstationary characteristics of the channel. In an attempt to solve these problems, this paper presents a new stochastic spatio-temporal propagation model. The model is a combination of the geometrically-based single reflection and the Gaussian wide-sense stationary uncorrelated scattering models, and is further enhanced in order to be able to handle nonstationary scenarios. The probability density functions of the number of multipath components, the scatterers' lifetime, and the angle of arrival are calculated to support these features. The input parameters of the model are based on results from measurement campaigns published in the open literature.
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paper_title: Geometrically based directional channel model for urban mobile communication systems

paper_content:

This paper proposes a geometrically based propagation model for an urban mobile environment that establishes a relationship between the angle-of-arrival and time-of-arrival of multipath components. The model is characterized by the geometric locations of a base station and mobile station among urban city structures. This model comprises three sets of propagation characteristics: the street-microcell propagation characteristics around mobile stations; the reflection and scattering characteristics around reflection areas; and the macrocell propagation characteristics from the reflection area to the base station. In particular, by using the propagation characteristics of a street-microcell around the mobile station, a more realistic model is established compared to previous models, which were based on circular or elliptic reflective areas.
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paper_title: A spatio-temporal channel model for position location techniques via AOA and TDOA

paper_content:

As a spatial and a temporal method, AOA (angle of arrival) and TDOA (time delay of arrival) are well known methods to locate wireless terminal position and have developed independently. Combination of the two methods has not been possible due to lack of the applicable and practical channel models. A common channel model is presented for the data fusing methodology for position location estimation. The temporal COST-207 models are utilized to provide the angular information for the AOA method to be cooperated. The angular characteristics of the channel can be obtained from the given temporal channel model, hence the possibility of fusion is now possible. Different properties of the methods are revealed to verify the proposition. The spatial diversity inherent among many elements of the antenna array is exploited to get the better channel path of many multipaths.
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paper_title: Geometrical-based statistical macrocell channel model for mobile environments

paper_content:

We develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival (AOA) of the multipath components, which are required to test adaptive array algorithms for cellular applications. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This geometrically based single bounce macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the AOA of the components. Using the GBSBM model, we analyze the effect of directional antennas at the base station on the fading envelopes. The level crossing rate of the fading envelope is reduced and the envelope correlation increases significantly if a directional antenna is employed at the base station.
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paper_title: Broadband Nearfield Beamforming Using a Radial Beampattern Transformation

paper_content:

This paper presents a new method of designing a beamformer having a desired nearfield broadband beampattern. The methodology uses the spherical harmonic solution to the wave equation to transform the desired nearfield beampattern to an equivalent farfield beampattern. A farfield beamformer is then designed for a transformed farfield beampattern that, if achieved, gives the desired nearfield pattern exactly. Salient features of the new method are as follows. (i) The nearfield patterns can be achieved for all angles, not just the primary look direction. (ii) There is no theoretical restriction on the bandwidth. (iii) General array geometries may be used. As an illustration, we apply the method to the problem of producing a practical array design that achieves a nearfield beampattern that is frequency invariant over an octave bandwidth, where at the lowest frequency, the array-source separation is three wavelengths.
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paper_title: First- and second-order characterization of direction dispersion and space selectivity in the radio channel

paper_content:

We present analytical results relating to first- and second-moment characterization of direction dispersion and spatial selectivity in the radio channel as well as to the duality between these two effects. Dispersion in direction can be characterized either by the direction power spectrum or by a family of spatial Doppler power spectra at the reception site. Two measures called the direction spread and the maximum spatial Doppler spread are introduced which describe the extent of channel dispersion in direction and in spatial Doppler frequency, respectively. Both measures are analogous to the delay and Doppler spreads, which are commonly employed to describe the extent of dispersion in delay and Doppler frequency, respectively. The relationships between the two approaches for characterizing spatial dispersion and especially between the direction and maximum spatial Doppler spreads are analytically established. The coherence distance at a certain level summarizes certain features of space selectivity in the radio channel which impact on the performance of communication systems. Two uncertainty relations between the direction spread and the coherence distance as well as between the maximum spatial Doppler spread and the coherence distance express the duality between direction dispersion and space selectivity. These relations are analogous to those established previously between the delay spread and the coherence bandwidth and between the Doppler spread and the coherence time. Examples relevant to mobile communications in the case where the waves propagate only horizontally illustrate the theoretical results. An application of these results to the design of uniform linear antenna arrays is also discussed.
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paper_title: Adaptive Array Principles

paper_content:

Adaptive arrays are a radical departure from conventional thinking in antenna design, offering substantial improvements in performance over fixed pattern antennas in environments that include severe interference and jamming. They achieve this because they are designed to steer nulls automatically at noise sources of unknown or variable direction and generally to modify their beampatterns to optimise performance. Adaptive array processing is applicable in most systems that exploit wave propagation; typical uses being radar, active and passive sonar, radio communication links, and radio monitoring. Although sensors and hardware for different applications vary, the same optimality criteria are used throughout and similar algorithms may be employed. This book develops the concepts underlying the design of adaptive arrays from first principles and is directed at research workers and designers whose mathematical background requires refurbishment in the special techniques that have accumulated around the field, often to the obscuration of the simple basic ideas. The topics treated include: single multiple null steering; derivation of the weighting coefficients in an array that maximises signal to noise ratio; online algorithms for achieving these coefficients using gradient methods based on correlators and coefficient peterbation; direct estimation of optimum coefficients by covariance matrix inversion and recursive techniques; prevention of null steering at the desired source and control over the main lobe shape; minimisation of the number of variable coefficients in suboptimal implementations.
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paper_title: Prediction of local mean power using 2-D ray-tracing-based propagation models

paper_content:

A new method is presented for the computation of local mean power from individual multipath signals predicted by two-dimensional ray-tracing-based propagation models. This method is based on an expression for the spatial average of the received power, which takes into account the spatial correlation between signals. Numerical results for some simple test configurations show that application of the common method of simply adding the ray powers can result in considerable errors, while the new method remains accurate-at the cost of slightly increased computational complexity.
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paper_title: Statistical modeling of small-scale fading in directional radio channels

paper_content:

After a review of the known description of time-variant channels by means of system and correlation functions, a consistent extension of this description to directional time-variant channels is described. This extension allows a clear distinction between time- and space-variant effects in directional mobile radio channels. The major intention of the described directional extension however is the derivation of a statistical modeling approach for small-scale fading effects in time-variant wideband directional channels, which can be regarded as a consistent extension of the well established Rayleigh or Rice-fading approach for nondirectional time-variant narrowband channels. The approach, which is based on the time and aperture-variant transfer function, appears to be preferable to the frequently used statistical modeling of the time-variant angle-resolved impulse response for several reasons. The major advantage is that the approach can cope with the demand for a great number of superimposing components as the basis for statistical modeling. The correlation between adjacent values is proposed to be achieved by filtering with appropriate directional scattering functions. The description of the modeling approach, as done in the present paper, is intended to be general and universal; for the application on certain channel types statistical distribution functions and parameters to be used with the approach can readily be determined from appropriate measurements.
---
paper_title: Mobile Communications Engineering

paper_content:

From the Publisher: ::: This authoritative work was written to be the bible for advanced commercial mobile phone systems and military mobile communications systems. Emphasizing how to study and analyze mobile communications problems,the book thoroughly explains how to design a mobile radio communication system. Introductory material describes existing systems,bridging the gap for students unfamiliar with the field. The characteristics of mobile radio signals are covered,applying statistical communication theory to propagation and received signal characteristics. Functional design is introduced,and a discussion of system performance included to explain how to evaluate a new system. The author uses both theory and experiments to support practical design and development of systems in the microwave frequency ranges configured for high-capacity mobile telephone and data communications.
---
paper_title: Wideband CDMA for third generation mobile communications

paper_content:

Basic principles of DS-CDMA applications radio operating environments and their impact into system design system design aspects a novel wieband CDMA radio interface typical wideband CDMA radio interfaces performance analysis time division duplex (TDD) DS-CDMA hierarchical cell structures implementation aspects radio nerwork planning and deployment network aspects comparison to TDMA and other 3rd generation radio interface proposals future developments.
---
paper_title: Characterization of Randomly Time-Variant Linear Channels

paper_content:

This paper is concerned with various aspects of the characterization of randomly time-variant linear channels. At the outset it is demonstrated that time-varying linear channels (or filters) may be characterized in an interesting symmetrical manner in time and frequency variables by arranging system functions in (timefrequency) dual pairs. Following this a statistical characterization of randomly time-variant linear channels is carried out in terms of correlation functions for the various system functions. These results are specialized by considering three classes of practically interesting channels. These are the wide-sense stationary (WSS) channel, the uncorrelated scattering (US) channel, and the wide-sense stationary uncorrelated scattering (WSSUS) channel. The WSS and US channels are shown to be (time-frequency) duals. Previous discussions of channel correlation functions and their relationships have dealt exclusively with the WSSUS channel. The point of view presented here of dealing with the dually related system functions and starting with the unrestricted linear channels is considerably more general and places in proper perspective previous results on the WSSUS channel. Some attention is given to the problem of characterizing radio channels. A model called the Quasi-WSSUS channel is presented to model the behavior of such channels. All real-life channels and signals have an essentially finite number of degrees of freedom due to restrictions on time duration and bandwidth. This fact may be used to derive useful canonical channel models with the aid of sampling theorems and power series expansions. Several new canonical channel models are derived in this paper, some of which are dual to those of Kailath.
---
paper_title: A model for the multipath delay profile of fixed wireless channels

paper_content:

This paper deals with the measurement and modeling of multipath delay on fixed wireless paths at 1.9 GHz in suburban environments. The primary focus is on the delay profile, which is the normalized plot of received power versus delay in response to an RT "impulse." We describe measurement campaigns in the western suburbs of Chicago, IL, and in suburban north-central New Jersey. Our analysis of the data suggests to us that, for directive terminal antennas, the delay profile can be modeled as having a "spike-plus-exponential" shape, i.e., a strong return ("spike") at the lowest delay, plus a set of returns whose mean powers decay exponentially with delay. This delay profile can be characterized by just two parameters (both variable over the terrain), namely, the ratio (K/sub 0/) of the average powers in the "spike" and "exponential" components and the decay time constant (/spl tau//sub 0/) of the "exponential" component. No such simple structure appears to apply for delay profiles using omnidirectional antennas. For a directive antenna with a 32/spl deg/ beamwidth, we find that: (1) the statistical correlation between the profile parameters K/sub 0/ and /spl tau//sub 0/ is negligible; (2) these parameters are relatively insensitive to antenna height and path length; and (3) over each measured region (Illinois and New Jersey), K/sub 0/ and /spl tau//sub 0/ have median values close to 8 dB and just below 0.2 /spl mu/s, respectively. Moreover, we have found simple probability distributions that accurately portray the variability of K/sub 0/ and /spl tau//sub 0/ over the terrain.
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paper_title: Clusterization of measured direction-of-arrival data in an urban macrocellular environment

paper_content:

Measured wideband direction-of-arrival data from urban macrocellular environment were clusterized. The clusterization was done by manual inspection. To understand the physical propagation channel, the source points of the extracted clusters were located to the local environment surrounding the mobile station. Some key parameters were calculated for each of the extracted clusters and for the residual power. By combining these parameters with the estimates of the cluster source points, assumptions on the propagation mechanisms of the clusters were drawn. According to the results the most significant sources are building structures above the average building height and corners of the buildings. This result is inline with previous studies in the urban propagation. Only a few significant clusters were found, in this study three clusters out of 14 extracted clusters contributed nearly 60% of the received power, while 19% of the power remained outside the clustering. Most of the clusters follow the Rician distribution with relatively high K-factor, while the residual power was Rayleigh distributed. There was only slight depolarization from the transmitted vertical polarization. One of the clusters was a clear exception with a negative XPR.
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paper_title: A statistical model of urban multipath propagation

paper_content:

An urban multipath propagation experiment, involving the simultaneous transmission from a fixed site of 100-ns pulses at 488, 1280, and 2920 MHz and their reception at a mobile van, is described. A statistical analysis of the data in the resulting multipath responses is given and used as a basis for a statistical model of urban multipath propagation.
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paper_title: A geometrically based model for line-of-sight multipath radio channels

paper_content:

This paper provides a geometrically based model for single bounce multipath components in line-of-sight (LOS) microcell radiowave propagation channels. The model characterizes the excess delay, direction-of-arrival, and received power of multipath components and is particular useful for microcell and PCS systems with low transmitter and receiver antenna heights. The model includes analytical expressions for the probability density functions for all critical channel parameters and is thus useful for analytical purposes. The model is also useful for simulating both wideband and narrowband systems and in particular the model has been used extensively in a study of code division multiple access (CDMA) cellular radio systems employing adaptive antennas and switched beam systems at the base station.
---
paper_title: A stochastic spatial channel model based on wave-propagation modeling

paper_content:

A novel stochastic spatial propagation channel model for wide-band spread spectrum applications is presented. The model is set up for indoor scenarios, although in principle it can be extended easily to urban environments. Deterministic ray-tracing results are used to produce the huge data sets required for the statistical evaluation of the parameters of the proposed model. The approach for the stochastic model is based on physical wave-propagation, where the channel is described by multipath components including angles of arrival at the receiver and angles of transmission at the transmitter. In each modeling step, path properties change according to the movement of the radio stations (RSs). The appearance and disappearance of multipath components is modeled by a genetic process. Especially, changing delay times of the propagation paths yield a realistic Doppler behavior of the channel. A new approach to model the directions of multipath components in three dimensions has been developed. By relating the angles of arrival (or transmission) to the direct line between transmitter and receiver, a universal modeling approach, which is independent of the actual geometry, becomes possible. The novel stochastic spatial channel model allows the simulation of complex systems including arbitrary antenna configurations and patterns. A detailed description of the overall model is presented together with some initial simulation results.
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paper_title: A geometrically based model for line-of-sight multipath radio channels

paper_content:

This paper provides a geometrically based model for single bounce multipath components in line-of-sight (LOS) microcell radiowave propagation channels. The model characterizes the excess delay, direction-of-arrival, and received power of multipath components and is particular useful for microcell and PCS systems with low transmitter and receiver antenna heights. The model includes analytical expressions for the probability density functions for all critical channel parameters and is thus useful for analytical purposes. The model is also useful for simulating both wideband and narrowband systems and in particular the model has been used extensively in a study of code division multiple access (CDMA) cellular radio systems employing adaptive antennas and switched beam systems at the base station.
---
paper_title: Indoor wideband time/angle of arrival multipath propagation results

paper_content:

Most current indoor propagation experiments measure the time of arrival of characteristics of multipath reflections without regard to the angle of arrival. Because of the increasing number of systems that are used indoors and which use multiple antenna systems to combat multipath interference, a need exists for indoor propagation data which takes the angle of arrival into account. A system is described which was used to collect simultaneous time and angle of arrival data in two indoor environments. A total of 65 data sets were taken in two buildings of different construction. The (7 GHz) data confirmed the temporal model proposed by Saleh and Valenzuela (1987), and showed a unique clustering pattern in angle, which consisted of clusters uniformly distributed in angle, with members of the clusters following a Laplacian distribution.
---
paper_title: A Statistical Model for Indoor Multipath Propagation

paper_content:

The results of indoor multipath propagation measurements using 10 ns, 1.5 GHz, radarlike pulses are presented for a medium-size office building. The observed channel was very slowly time varying, with the delay spread extending over a range up to about 200 ns and rms values of up to about 50 ns. The attenuation varied over a 60 dB dynamic range. A simple statistical multipath model of the indoor radio channel is also presented, which fits our measurements well, and more importantly, appears to be extendable to other buildings. With this model, the received signal rays arrive in clusters. The rays have independent uniform phases, and independent Rayleigh amplitudes with variances that decay exponentially with cluster and ray delays. The clusters, and the rays within the cluster, form Poisson arrival processes with different, but fixed, rates. The clusters are formed by the building superstructure, while the individual rays are formed by objects in the vicinities of the transmitter and the receiver.
---
paper_title: Geometrical-based statistical macrocell channel model for mobile environments

paper_content:

We develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival (AOA) of the multipath components, which are required to test adaptive array algorithms for cellular applications. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This geometrically based single bounce macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the AOA of the components. Using the GBSBM model, we analyze the effect of directional antennas at the base station on the fading envelopes. The level crossing rate of the fading envelope is reduced and the envelope correlation increases significantly if a directional antenna is employed at the base station.
---
paper_title: Stochastic radio channel model for advanced indoor mobile communication systems

paper_content:

A stochastic radio channel model (SRCM) for broadband indoor mobile systems operating at 5.2 and 17 GHz has been derived within the ACTS project AC085 Magic WAND. The SRCM accurately describes the dispersive nature of real radio channels in time, frequency, direction, and polarization. These effects are important for the design and performance evaluation of advanced receiver structures that exploit the inherent channel diversity, e.g., by means of adaptive antennas. The wideband SRCM takes into account all relevant propagation effects observed in real indoor environments. For example, it includes large-scale fluctuations such as transitions where waves are emerging and vanishing as well as the delay drift of the waves. In the paper, the modeling approach adopted for the SRCM is described and illustrated by simulation results.
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paper_title: Unified channel model for mobile radio systems with smart antennas

paper_content:

The definition of flat fading and frequency-selective fading channels is extended to low-rank and high-rank channels to include the angular domain. By physical reasoning a generic channel model is introduced incorporating directions of arrival and a set of parameters is given for its configuration. The time evolution of the scattering processes and directions of arrival is taken into account. Analytical expressions are derived for space-correlation coefficients and frequency-correlation coefficients. Spatial correlation decreases with increasing angular spread and decreasing angle of incidence, measured from array broadside.
---
paper_title: Characterization of Randomly Time-Variant Linear Channels

paper_content:

This paper is concerned with various aspects of the characterization of randomly time-variant linear channels. At the outset it is demonstrated that time-varying linear channels (or filters) may be characterized in an interesting symmetrical manner in time and frequency variables by arranging system functions in (timefrequency) dual pairs. Following this a statistical characterization of randomly time-variant linear channels is carried out in terms of correlation functions for the various system functions. These results are specialized by considering three classes of practically interesting channels. These are the wide-sense stationary (WSS) channel, the uncorrelated scattering (US) channel, and the wide-sense stationary uncorrelated scattering (WSSUS) channel. The WSS and US channels are shown to be (time-frequency) duals. Previous discussions of channel correlation functions and their relationships have dealt exclusively with the WSSUS channel. The point of view presented here of dealing with the dually related system functions and starting with the unrestricted linear channels is considerably more general and places in proper perspective previous results on the WSSUS channel. Some attention is given to the problem of characterizing radio channels. A model called the Quasi-WSSUS channel is presented to model the behavior of such channels. All real-life channels and signals have an essentially finite number of degrees of freedom due to restrictions on time duration and bandwidth. This fact may be used to derive useful canonical channel models with the aid of sampling theorems and power series expansions. Several new canonical channel models are derived in this paper, some of which are dual to those of Kailath.
---
paper_title: Unified channel model for mobile radio systems with smart antennas

paper_content:

The definition of flat fading and frequency-selective fading channels is extended to low-rank and high-rank channels to include the angular domain. By physical reasoning a generic channel model is introduced incorporating directions of arrival and a set of parameters is given for its configuration. The time evolution of the scattering processes and directions of arrival is taken into account. Analytical expressions are derived for space-correlation coefficients and frequency-correlation coefficients. Spatial correlation decreases with increasing angular spread and decreasing angle of incidence, measured from array broadside.
---
paper_title: A geometrically based model for line-of-sight multipath radio channels

paper_content:

This paper provides a geometrically based model for single bounce multipath components in line-of-sight (LOS) microcell radiowave propagation channels. The model characterizes the excess delay, direction-of-arrival, and received power of multipath components and is particular useful for microcell and PCS systems with low transmitter and receiver antenna heights. The model includes analytical expressions for the probability density functions for all critical channel parameters and is thus useful for analytical purposes. The model is also useful for simulating both wideband and narrowband systems and in particular the model has been used extensively in a study of code division multiple access (CDMA) cellular radio systems employing adaptive antennas and switched beam systems at the base station.
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paper_title: Geometrical-based statistical macrocell channel model for mobile environments

paper_content:

We develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival (AOA) of the multipath components, which are required to test adaptive array algorithms for cellular applications. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This geometrically based single bounce macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the AOA of the components. Using the GBSBM model, we analyze the effect of directional antennas at the base station on the fading envelopes. The level crossing rate of the fading envelope is reduced and the envelope correlation increases significantly if a directional antenna is employed at the base station.
---
paper_title: Efficient implementation of a geometry-based directional model for mobile radio channels

paper_content:

For the design and simulation of adaptive antenna systems, realistic and efficient spatial channel models are required. We investigate the so-called "geometry-based stochastic channel model" (GSCM), where the probability density function (PDF) of the location of the scatterers is prescribed. We analyse methods to efficiently implement GSCM, namely by nonuniform weighting of the scattering cross sections, and by combination with purely stochastic approaches. We then present various extensions of the model in urban environments, especially for wave guiding by street canyons.
---
paper_title: GENERATION OF BASE STATION DOA DISTRIBUTIONS BY JACOBI TRANSFORMATION OF SCATTERING AREAS

paper_content:

The author describes a simple method for transforming angular distributions of a radio scattering area located around a mobile station (MS) into a direction-of-arrival (DOA) distribution at a base station (BS). Tractable closed form solutions for circular uniform and conical (nonuniform) scattering areas, are presented.
---
paper_title: Directional macro-cell channel characterization from urban measurements

paper_content:

We measured the angular power distribution at the mobile station in downtown Paris at 890 MHz. The transmit antenna was omnidirectional and placed high above rooftops. The receiver antenna, a 21/spl times/41 element rectangular synthetic array, was located on the roof of a van. The refined high-resolution evaluation method, particularly robust against nonstationary signal components, allows an angular resolution of better than 1/spl deg/ in both azimuth and elevation and a delay resolution of 33 ns. Combined angular/temporal domain measurements are crucial for the understanding of the propagation mechanisms. The evaluated sites showed strongly street-dominated propagation. We found a combined circular and rectangular distribution of scatterers around the mobile station in street-dominated environments. Propagation over the roofs was significant; typically 65% of energy was incident with elevation larger than 100. Our results corroborate the hypothesis on the importance of multiple reflections/diffractions in urban macro cells. We explain this behavior by two reasons: narrow streets favoring a canyon effect and strong scatterers without line-of-sight (LOS) to the mobile station.
---
paper_title: A space-time correlation model for multielement antenna systems in mobile fading channels

paper_content:

Analysis and design of multielement antenna systems in mobile fading channels require a model for the space-time cross correlation among the links of the underlying multiple-input multiple-output (MIMO) channel. In this paper, we propose a general space-time cross-correlation function for mobile frequency nonselective Rice fading MIMO channels, in which various parameters of interest such as the angle spreads at the base station and the user, the distance between the base station and the user, mean directions of the signal arrivals, array configurations, and Doppler spread are all taken into account. The new space-time cross-correlation function includes all the relevant parameters of the MIMO fading channel in a clean compact form, suitable for both mathematical analysis and numerical calculations/simulations. It also covers many known correlation models as special cases. We demonstrate the utility of the new space-time correlation model by clarifying the limitations of a widely accepted correlation model for MIMO fading channels. As another application, we quantify the impact of nonisotropic scattering around the user, on the capacity of a MIMO fading channel.
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paper_title: Spatial channel characteristics in outdoor environments and their impact on BS antenna system performance

paper_content:

This paper present measurement results obtained with a testbed equipped with an array antenna. The investigations focus on the power azimuth spectrum of the channel in urban and rural areas, for various base station antenna heights. The power azimuth spectrum is well modeled with a Laplacian function. The local azimuth spread is found to range from 1/spl deg/ to 25/spl deg/ depending on the environment and antenna height. The azimuth spread significantly increases as the antenna height is reduced. An analytical expression for the spatial correlation function is derived based on the Laplacian model. Finally, the power azimuth spectrums impact on a conventional beamformer ability to suppress interfering users is investigated.
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paper_title: Experimental characterization of DOA at the base station in rural and urban area

paper_content:

Techniques such as beam-forming use the property that energy transmitted by a mobile reaches the base station with a small angle aperture. This paper examines that property from experimental data from different environments. Examples and angular statistical results are given. Finally, a wideband multi-sensor propagation model based on a REVAL model is proposed for the urban environments.
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paper_title: A stochastic multipath channel model including path directions for indoor environments

paper_content:

A novel stochastic channel model for the indoor propagation channel is presented. It is especially for, but not limited to future communication systems with multiple antennas like space division multiple access (SDMA), spatial filtering for interference reduction (SFIR), or multiple-input/multiple-output (MIMO). The model is designed for indoor scenarios, straight forward extendable to urban environments. It is based on physical wave propagation. The new approach describes the channel by multipath components, each characterized by its transfer matrix (including loss), delay, direction of arrival, and departure. The appearance and disappearance of multipath components over time is modeled as a birth and death process, a marked Poisson process. This enables first-time the correct modeling of spatial and temporal correlations. In each modeling step, path properties change according to the motion of transmitter and receiver. The changing delay times of propagation paths yield a realistic Doppler behavior of the channel. Deterministic ray tracing results are used to produce the huge data sets required for the statistical evaluation of the parameters of the proposed model. This method enables an automated parameter extraction for new environments or frequencies. The ray tracing tool has been verified by narrowband, wideband, and directional channel measurements. The novel stochastic spatial channel model allows the simulation of third-generation broadband radio systems including arbitrary antenna configurations and patterns. System simulations for the bit-error rate of radio links can be performed including intelligent antenna configurations like SDMA, SFIR, or MIMO. Furthermore, the capacity of complete systems can be investigated.
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paper_title: Diffuse channel model and experimental results for array antennas in mobile environments

paper_content:

A wide-band spatial model of the mobile channel has been developed. The model allows the inclusion of array antennas at the base station. The diffuse scattering is modeled using dense discrete scatterers. An algebraic power decay is used for the path loss to the scatterers of the environment and to the mobile. Results from the model are compared with experimental results obtained at 1800 MHz. The parameters that are used are delay spread, power window, and angular spread of incident power. The model elucidates the general diffuse background scattering in a rural and an urban environment. It can be extended with inclusion of spatial specular scatterers where appropriate.
---
paper_title: Clusterization of measured direction-of-arrival data in an urban macrocellular environment

paper_content:

Measured wideband direction-of-arrival data from urban macrocellular environment were clusterized. The clusterization was done by manual inspection. To understand the physical propagation channel, the source points of the extracted clusters were located to the local environment surrounding the mobile station. Some key parameters were calculated for each of the extracted clusters and for the residual power. By combining these parameters with the estimates of the cluster source points, assumptions on the propagation mechanisms of the clusters were drawn. According to the results the most significant sources are building structures above the average building height and corners of the buildings. This result is inline with previous studies in the urban propagation. Only a few significant clusters were found, in this study three clusters out of 14 extracted clusters contributed nearly 60% of the received power, while 19% of the power remained outside the clustering. Most of the clusters follow the Rician distribution with relatively high K-factor, while the residual power was Rayleigh distributed. There was only slight depolarization from the transmitted vertical polarization. One of the clusters was a clear exception with a negative XPR.
---
paper_title: A wideband directional channel model for UMTS microcells

paper_content:

The development of a planar wideband directional channel model applicable to UMTS microcells is addressed. The model, a statistical one based on geometrical considerations, is implemented and simulated, its assessment being based on global parameters of channel impulse responses obtained from measurement results. Exemplifying results for the directional channel impulse response are depicted for streets based on the city of Lisbon. For longer distances, system performance improvement is expected when using adaptive antennas.
---
paper_title: Radio Propagation for Modern Wireless Systems

paper_content:

From the Book: ::: PREFACE: Preface ::: The commercial success of cellular mobile radio since its initial implementation in the early 1980s has led to an intense interest among wireless engineers in understanding and predicting radio propagation characteristics within cities, and even within buildings. In this book we discuss radio propagation with two goals in mind. The first is to provide practicing engineers having limited knowledge of propagation with an overview of the observed characteristics of the radio channel and an understanding of the process and factors that influence these characteristics. The second goal is to serve as text for a master's-level course for students intending to work in the wireless industry. Books on modern wireless applications typically survey the issues involved, devoting only one or two chapters to radio channel characteristics, or focus on how the characteristics influence system performance. Now that the wireless field has grown in scope and size, it is appropriate that books such as this one examine in greater depth the various underlying topics that govern the design and operation of wireless systems. The material for this book has grown out of tutorials given by the author to engineering professionals and a course on wireless propagation given by the author at Polytechnic University as part of a program in wireless networks. It also draws upon the 15 years of experience the author and his students have had in understanding and predicting propagation effects. ::: Cellular telephones gave the public an active role in the use of the radio spectrum as opposed to the previous role of passive listener. This social revolution in the use of theradiospectrum ultimately changed governmental views of its regulation. Driven by the requirement to allow many users to operate in the same band, cellular telephones also created a technical revolution through the concept of spectral reuse. Systems that do not employ spectral reuse avoid interference by operating in different frequency bands and are limited in performance primarily by noise. In these systems, lack of knowledge of the propagation conditions can be compensated for by increasing the transmitted power, up to regulatory limits. In contrast, the concept of spectral reuse acknowledges that in commercially successful systems, interference from other users will be the primary factor limiting performance. In designing these systems, it is necessary to balance the desired signal for each user against interference from signals intended for other users. Finding the balance requires knowledge of the radio channel characteristics. Chapter 1 is intended to introduce the student reader to the concept of spectrum reuse and in the process to give examples of how the propagation characteristics influence the balance between desired signal and interference, and thereby influence system design. As in all chapters, examples are discussed to illustrate the concepts, and problems are included at the end of the chapter to give the students experience in applying the concepts. ::: In modern systems, the radio links are about 20 kilometers or less, the antennas that create the links lie near to or among the buildings or even inside the buildings, and the wavelength is small compared to the building dimensions. As a result, the channel characteristics are strongly influenced by the buildings as well as by vegetation and terrain. In this environment, signals propagate from one antenna to the other over multiple paths that involve the processes of reflection and transmission at walls and by the ground and the process of diffraction at building edges and terrain obstacles. The multipath nature of the propagation makes itself felt in a variety of ways that have challenged the inventiveness of communication engineers. Although initially a strong limitation on channel capacity, engineers have begun to find ways to harness the multipath signals so as to achieve capacities that approach the theoretical limit. However, each new concept for dealing with multipath calls for an even deeper understanding of the statistical characteristics of the radio channel. In Chapter 2 we describe many of the propagation effects that have been observed in various types of measurements, ranging from path loss for narrowband signals, to angle of arrival and delay spread for wideband transmission. As in other chapters, an extensive list of references is cited to aid the professional seeking a detailed understanding of particular topics. For the student reader, this chapter serves as an introduction to the types of measurements that are made, the methods used to process the data, and some of the statistical approaches used to represent the results. Understanding the measurements, their processing, and their representation also serves to guide the theoretical modeling described in subsequent chapters. ::: The level of presentation assumes that the reader has had an undergraduate course in electromagnetics with exposure to wave concepts. The presentation does not attempt to derive the propagation characteristics from Maxwell's equations rigorously; rather, the goal is to avoid vector calculus. The reader's background is relied on for acceptance of some wave properties; other properties are motivated through heuristic arguments and from basic ideas, such as conservation of power. For example, in Chapter 3 we start with the fundamental properties of plane waves and call on the reader's background in transmission lines when discussing reflection and transmission at the ground and walls. Wherever possible in this and following chapters, the theoretical results are compared to measurements. Thus plane waves are used to model observed interference effects, which are referred to as fast fading, and to model Doppler spreading. Plane wave properties and conservation of power are used in Chapter 4 to justify the properties of spherical waves radiated by antennas and to motivate the ray description of reflection at material surfaces. By accounting for these reflections, propagation on line-of-sight paths in urban canyons is modeled. Circuit concepts are used to obtain the reciprocity of propagation between antennas, and to derive expressions for path gain or loss. ::: Diffraction at building edges is an important process in wireless communications. It allows signals to reach subscribers who would otherwise be shadowed by the buildings. Because the reader is not expected to be familiar with this process, Chapter 5 explores diffraction in some detail. For simplicity, the scalar form of the Huygens-Kirchhoff integral is use as a starting point. We first use it to give physical meaning to the Fresnel ellipsoid about a ray, which is widely employed in propagation studies to scale physical dimensions. The geometrical and uniform forms of the fields diffracted by an absorbing half screen are derived. In these expressions we identify a universal component that applies to diffraction by any straight building edge or corner and a diffraction coefficient whose specific form is dependent on the nature of the edge. Diffraction coefficients for several types of edges and corners are given without derivation. Using heuristic ray arguments, the results obtained for plane waves are generalized to spherical waves radiated by antennas and to multiple edges. These results are cast in terms of path gain or loss, which is convenient for wireless applications. ::: Chapter 6 formulates the problem of average path loss in residential environments in terms of multiple diffraction past rows of buildings. Relying on the Huygens-Kirchhoff formulation, the diffraction problem is solved for various ranges of base station and subscriber antenna height. These results show how the frequency, average building height, and row separation influence the range dependence and height gain of the signal. This approach to diffraction is used in Chapter 7 to investigate the effects of randomness in building construction on shadow fading. Chapter 7 also makes use of diffraction to examine the effects of terrain and vegetation on the average path loss. ::: Propagation predictions that make use of a geometrical description of individual buildings are discussed in Chapter 8. Various ray-based models that incorporated the processes of reflection and diffraction at buildings have been developed to make such site-specific predictions. Their accuracy has been evaluated primarily by comparing predictions against measurements of the small area average received signal. However, the ray models have started to be used to predict higher-order channel statistics, such as time delay and angle spread, through Monte Carlo simulations. This approach can generate values for the statistical descriptors of the radio channel that are employed in advanced communication systems and show how these values depend on the distribution of building size and shape in different cities.
---
paper_title: Spatio-temporal radio channel characteristics in urban macrocells

paper_content:

The performance assessment of new mobile radio base station (BS) transceiver concepts with adaptive intelligent antennas requires realistic directional radio channel models. An appropriate model is derived from the results of an extensive uplink sounding campaign performed at 1.9 GHz in a urban macrocell within the city of Frankfurt. In the experiments the wideband sounder RUSK XL was applied for synthetic aperture reception. The directional multipath propagation is characterised by means of delays, directions of arrival (DOA) at the BS antenna array and mean powers of the multipath components. The coupled delay-DOA-power information is determined by an adaptation of the 2-D unitary ESPRIT algorithm. It can be used directly to configure fading simulators for multiple antenna reception which reflect real-world small-area radio channel properties in simulations at the link level. Additionally, probability distribution functions for excess delays, DOAs and mean powers are derived from the measurement results. They are useful for consideration of directional propagation effects in investigations of the cellular system behaviour.
---
paper_title: Directional macro-cell channel characterization from urban measurements

paper_content:

We measured the angular power distribution at the mobile station in downtown Paris at 890 MHz. The transmit antenna was omnidirectional and placed high above rooftops. The receiver antenna, a 21/spl times/41 element rectangular synthetic array, was located on the roof of a van. The refined high-resolution evaluation method, particularly robust against nonstationary signal components, allows an angular resolution of better than 1/spl deg/ in both azimuth and elevation and a delay resolution of 33 ns. Combined angular/temporal domain measurements are crucial for the understanding of the propagation mechanisms. The evaluated sites showed strongly street-dominated propagation. We found a combined circular and rectangular distribution of scatterers around the mobile station in street-dominated environments. Propagation over the roofs was significant; typically 65% of energy was incident with elevation larger than 100. Our results corroborate the hypothesis on the importance of multiple reflections/diffractions in urban macro cells. We explain this behavior by two reasons: narrow streets favoring a canyon effect and strong scatterers without line-of-sight (LOS) to the mobile station.
---
paper_title: A new stochastic spatio-temporal propagation model (SSTPM) for mobile communications with antenna arrays

paper_content:

In order to evaluate the performance of third-generation mobile communication systems, radio channel models are required. The models should be capable of handling nonstationary scenarios with dynamic evolution of multipath. In this context and due to the introduction of advanced antenna systems to exploit the spatial domain, a further expansion is needed in order to include the nonstationary characteristics of the channel. In an attempt to solve these problems, this paper presents a new stochastic spatio-temporal propagation model. The model is a combination of the geometrically-based single reflection and the Gaussian wide-sense stationary uncorrelated scattering models, and is further enhanced in order to be able to handle nonstationary scenarios. The probability density functions of the number of multipath components, the scatterers' lifetime, and the angle of arrival are calculated to support these features. The input parameters of the model are based on results from measurement campaigns published in the open literature.
---
paper_title: Geometrically based directional channel model for urban mobile communication systems

paper_content:

This paper proposes a geometrically based propagation model for an urban mobile environment that establishes a relationship between the angle-of-arrival and time-of-arrival of multipath components. The model is characterized by the geometric locations of a base station and mobile station among urban city structures. This model comprises three sets of propagation characteristics: the street-microcell propagation characteristics around mobile stations; the reflection and scattering characteristics around reflection areas; and the macrocell propagation characteristics from the reflection area to the base station. In particular, by using the propagation characteristics of a street-microcell around the mobile station, a more realistic model is established compared to previous models, which were based on circular or elliptic reflective areas.
---
paper_title: Statistical characterization of urban spatial radio channels

paper_content:

We present a statistical analysis of wideband three-dimensional channel measurements at base station locations in an urban environment. Plots of the received energy over azimuth, elevation, and delay planes suggest that the incident waves group to clusters in most measured transmitter positions. A super-resolution algorithm (Unitary ESPRIT) allows one to resolve individual multipath components in such clusters and hence enables a detailed statistical analysis of the propagation properties. The origins of clusters-sometimes even individual multipath components-such as street apertures, large buildings, roof edges, or building corners can be localized on the city map. Street guided propagation dominates most of the scenarios (78%-97% of the total received power), while quasi-line-of-sight over-the-rooftop components are weak(3%-13% of the total received power). For this measurement campaign, in 90% of the cases, 75% of the total received power is concentrated in the two strongest clusters, but only 55% in the strongest one. Our analysis yields an exponential decay of power with 8.9 dB//spl mu/s, and a standard deviation of the log-normally distributed deviations from the exponential of 9.0 dB. The power of cross-polarized components is 8 dB below copolarized ones on average (vertical transmission).
---
paper_title: Diffuse channel model and experimental results for array antennas in mobile environments

paper_content:

A wide-band spatial model of the mobile channel has been developed. The model allows the inclusion of array antennas at the base station. The diffuse scattering is modeled using dense discrete scatterers. An algebraic power decay is used for the path loss to the scatterers of the environment and to the mobile. Results from the model are compared with experimental results obtained at 1800 MHz. The parameters that are used are delay spread, power window, and angular spread of incident power. The model elucidates the general diffuse background scattering in a rural and an urban environment. It can be extended with inclusion of spatial specular scatterers where appropriate.
---
paper_title: A wideband directional channel model for UMTS microcells

paper_content:

The development of a planar wideband directional channel model applicable to UMTS microcells is addressed. The model, a statistical one based on geometrical considerations, is implemented and simulated, its assessment being based on global parameters of channel impulse responses obtained from measurement results. Exemplifying results for the directional channel impulse response are depicted for streets based on the city of Lisbon. For longer distances, system performance improvement is expected when using adaptive antennas.
---
paper_title: A new stochastic spatio-temporal propagation model (SSTPM) for mobile communications with antenna arrays

paper_content:

In order to evaluate the performance of third-generation mobile communication systems, radio channel models are required. The models should be capable of handling nonstationary scenarios with dynamic evolution of multipath. In this context and due to the introduction of advanced antenna systems to exploit the spatial domain, a further expansion is needed in order to include the nonstationary characteristics of the channel. In an attempt to solve these problems, this paper presents a new stochastic spatio-temporal propagation model. The model is a combination of the geometrically-based single reflection and the Gaussian wide-sense stationary uncorrelated scattering models, and is further enhanced in order to be able to handle nonstationary scenarios. The probability density functions of the number of multipath components, the scatterers' lifetime, and the angle of arrival are calculated to support these features. The input parameters of the model are based on results from measurement campaigns published in the open literature.
---
paper_title: Geometrically based directional channel model for urban mobile communication systems

paper_content:

This paper proposes a geometrically based propagation model for an urban mobile environment that establishes a relationship between the angle-of-arrival and time-of-arrival of multipath components. The model is characterized by the geometric locations of a base station and mobile station among urban city structures. This model comprises three sets of propagation characteristics: the street-microcell propagation characteristics around mobile stations; the reflection and scattering characteristics around reflection areas; and the macrocell propagation characteristics from the reflection area to the base station. In particular, by using the propagation characteristics of a street-microcell around the mobile station, a more realistic model is established compared to previous models, which were based on circular or elliptic reflective areas.
---
paper_title: Molisch, “The ultra-wide bandwidth indoor channel: from statistical model to simulations

paper_content:

We establish a statistical model for the ultra-wide bandwidth (UWB) indoor channel based on an extensive measurement campaign in a typical modern office building with 2-ns delay resolution. The approach is based on the investigation of the statistical properties of the multipath profiles measured in different rooms over a finely spaced measurement grid. The analysis leads to the formulation of a stochastic tapped-delay-line (STDL) model of the UWB indoor channel. The averaged power delay profile can be well-modeled by a single exponential decay with a statistically distributed decay constant. The small-scale statistics of path energy gains follow Gamma distributions whose parameters m are truncated Gaussian variables with mean values and standard deviations decreasing with delay. The total received energy experiences a lognormal shadowing around the mean energy given by the path-loss power law. We also find that the correlation between multipath components is negligible. Finally, we propose an implementation of the STDL model and give a comparison between the experimental data and the simulation results.
---
paper_title: Backward compatibility of the COST259 directional channel model

paper_content:

We consider the COST259 directional channel model (DCM) in relation to other existing channel models. The COST259 DCM is a general model for the mobile radio channel that includes narrowband power (field strength), power delay profiles, and directions of arrival. For comparison purposes, it is desirable that the channel models forming the basis of earlier simulations are contained as special cases in the COST259 DCM. We show how a mixed stochastic/deterministic approach allows the GSM wideband models to be kept as special cases of COST259 DCM while still including new measurement results. The mean received powers agree with M. Hata's model (see IEEE Trans. on VT, vol.29, p.317-25, 1980) when proper averaging over stochastic variables is done. Finally, the shadowing distribution of the narrowband power is shown to agree with M. Gudmundson's model (see Electronic Letters, vol.27, no.23, p.2145-6,1991).
---
paper_title: A model for the multipath delay profile of fixed wireless channels

paper_content:

This paper deals with the measurement and modeling of multipath delay on fixed wireless paths at 1.9 GHz in suburban environments. The primary focus is on the delay profile, which is the normalized plot of received power versus delay in response to an RT "impulse." We describe measurement campaigns in the western suburbs of Chicago, IL, and in suburban north-central New Jersey. Our analysis of the data suggests to us that, for directive terminal antennas, the delay profile can be modeled as having a "spike-plus-exponential" shape, i.e., a strong return ("spike") at the lowest delay, plus a set of returns whose mean powers decay exponentially with delay. This delay profile can be characterized by just two parameters (both variable over the terrain), namely, the ratio (K/sub 0/) of the average powers in the "spike" and "exponential" components and the decay time constant (/spl tau//sub 0/) of the "exponential" component. No such simple structure appears to apply for delay profiles using omnidirectional antennas. For a directive antenna with a 32/spl deg/ beamwidth, we find that: (1) the statistical correlation between the profile parameters K/sub 0/ and /spl tau//sub 0/ is negligible; (2) these parameters are relatively insensitive to antenna height and path length; and (3) over each measured region (Illinois and New Jersey), K/sub 0/ and /spl tau//sub 0/ have median values close to 8 dB and just below 0.2 /spl mu/s, respectively. Moreover, we have found simple probability distributions that accurately portray the variability of K/sub 0/ and /spl tau//sub 0/ over the terrain.
---
paper_title: Statistical analysis of the UWB channel in an industrial environment

paper_content:

In this paper, we present a statistical model for the ultra-wideband (UWB) channel in an industrial environment. Based on a set of measurements in a factory hall, we find that the abundance of metallic scatterers causes dense multipath scattering. This can be seen to produce mostly a Rayleigh distributed small-scale fading signal, with only a few paths exhibiting Nakagami distributions. For the power delay profile, we suggest a generalization of the Saleh-Valenzuela model where clusters with different excess delays have different ray power decay constants; the decay constants follow a linear dependence on the delay. This model provides an excellent fit to the measured data. We also note that for non-line-of-sight scenarios at larger distances, several hundred multipath components need to be collected to capture 50% of the available energy.
---
paper_title: Temporal radio channel variations with stationary terminal

paper_content:

In wireless communications, stationary terminal scenarios are becoming increasingly important as bitrates goes up. Consequently, the need to improve the knowledge about the channel behavior and to develop realistic channel models for these scenarios is also increasing. The present work comprises both measurements and modeling of the radio channel when the terminal is stationary. The measurements were performed at 5 GHz in indoor scenarios using a vector network analyzer. The measured channel was essentially static most of the time. Only about 1% of the time did it show substantial channel variations. An important finding is that the dominant cause for temporal channel variations in the measurements was the movement of persons in the vicinity of either antenna. This is also supported by a simple model, based on a single moving scatterer, which shows good agreement with measurements.
---

Title: The COST259 Directional Channel Model-Part I: Overview and Methodology

Section 1: Physical Properties of Mobile Radio Channels
Description 1: Discusses how energy radiated by the transmitter interacts with the environment, leading to multipath propagation.

Section 2: The Directional Channel Impulse Response Function
Description 2: Describes the dispersion characteristics of a propagation channel in delay and angle of incidence using the directional impulse response function.

Section 3: Stationary IOs
Description 3: Examines the assumption that the interacting objects (IOs) are stationary and discusses its implications and applicability.

Section 4: Modeling Constructs and Their Hierarchy
Description 4: Introduces the hierarchical structure of the modeling constructs for the radio channels and describes the different radio environments and propagation scenarios.

Section 5: Radio Channel Simulation Methods
Description 5: Discusses the methods proposed for the simulation of radio channel impulse response functions (CIRs).

Section 6: Propagation Scenarios
Description 6: Outlines the different propagation scenarios and their characteristics based on topographical and electromagnetic features.

Section 7: Parameter Types
Description 7: Defines the different parameter types used in the model, such as global parameters (GPs) and local parameters (LPs).

Section 8: Cell Types
Description 8: Distinguishes between different cell types (macro, micro, pico) and their characteristics.

Section 9: Radio Environments
Description 9: Describes the specific radio environments within each cell type, including urban, rural, corridor, office, and factory/hall scenarios.

Section 10: The Generation of CIRs
Description 10: Explains the processes and considerations for generating channel impulse response functions within the COST259 framework.

Section 11: Transitions Between Radio Environments
Description 11: Discusses how transitions between different radio environments are modeled and implemented in the channel models.

Section 12: Transition Between Cell Types
Description 12: Explores the factors and methodologies for modeling transitions between different cell types, such as handovers.

Section 13: Clustering
Description 13: Defines and explains the concept of clustering in radio channels and how multipath components often arrive in clusters.

Section 14: The Virtual Deployment Area
Description 14: Introduces the concept of Virtual Deployment Areas (VDAs) for micro and picocells and how they are used to model specific environments.

Section 15: The Number of Multipath Components
Description 15: Examines how the number of multipath components is determined within the model and the implications for different resolutions.

Section 16: Summary and Recommendations for Future Work
Description 16: Summarizes the concepts of the COST259 DCM and suggests areas for future research to address limitations and improve the model.