A ubiquitous and high-performance sensing service is required in the next generation of wireless communication systems. The legacy Sub-6GHz bands can provide a larger sensing range, but the available bandwidth limits the resolution. In contrast, the millimeter-wave (mmWave) frequencies enhance the sensing performance with wider bandwidth. However, high-directional beamforming poses new challenges in passive target surveillance. The conventional beam sweeping in mm Wave is costly due to the significant overhead, which conflicts with the goal of communication on efficient data transmission. To reduce the overhead caused by target surveillance, we propose a dual-band sensing approach. By combining the advantages of both Sub-6GHz and mmWave frequencies, our method enables fine target detection in a wide area. Compared to beam sweeping, the pro-posed method significantly reduces the communication overhead and time consumption, while also lightening the computational load of radar signal processing.

In integrated sensing and communication (ISAC) systems, the radar and communication functionality share the same infrastructure and radio resources. The flexible access scheme in mobile communication systems allows for variable and efficient radio resource allocation for multiple users and services. In this paper, we present a resource allocation strategy for Orthogonal Frequency Division Multiple (OFDM) based radar sensing. Furthermore, we propose a Deep Reinforcement Learning (DRL) method combined with classic OFDM radar signal processing techniques to optimize the radio resources for radar sensing. Two agents are trained with the DRL method on simulated data to predict the radio resources for the subsequent signal, aiming to achieve the required radar performance while improving the resource efficiency. One agent optimizes the transmission power, while the other optimizes the signal bandwidth/duration. The investigated scenario is a highway with traffic. We evaluate the performance of the agents based on detection loss and radio resource efficiency the metrics. Further, we compare the results against random and maximum resource-selecting agents.

Integrated Communication and Sensing (ICAS) rep-resents an exciting new research field that combines communication and radar sensing functionalities under a single platform. This convergence leverages the similarities in signal processing, spectrum utilization, and system design between the two functionalities. The main difference between sensing and communication is their ability to use different segments of the propagation channel because of their distinct system requirements. In Vehicular Ad-hoc Networks (VANETs), existing channel models are designed purely for V2V (Vehicle to Vehicle) or V2X (Vehicle to Anything) communications. With the sole purpose of communication, such channel models lack the capability of radar sensing. ICAS demands simultaneous communication and target sensing. Therefore, in this paper, we extended a communication-based V2V channel model to integrate target detection, thus realizing an ICAS system. We considered a two-way highway scenario in the presence of Diffuse (DI) scattering components. DI components can result in high-power reflections for small distances. Therefore, the integration of the DI components is vital for the development of accurate target detection algorithms. In our simulations, we showed that the extended ICAS channel model can detect Dynamic Targets (DT) alongside its communication functionality. In addition, we also demonstrate the impact of a strong Direct Link (DL) between the Transmitter (Tx) and Receiver (Rx) on target detection.

We present our new scalable multi-channel and multi-node sounder, the ILMSoundG3. It is configurable in terms of the number of switched Tx and parallel Rx nodes. The basic structures of the Tx and Rx nodes are given with consideration of the measurement system requirements.The ILMSoundG3is validated via a proof of concept measurement at 2.53 GHz in an urban environment. The system was configured as a sounder with two Tx nodes and one Rx node, which records two MIMO links simultaneously. Each node uses an antenna array. The transmitters were moved by cars whereas the receiver was elevated 20 m above the ground by a lifting platform acting as a base station. The used system configuration results in a snapshot rate of approx. 0.5 kHz, which covers the expected time variance of the chosen environment.The measurement results were analyzed using HRPE, providing a parametric description of the specular propagation paths of the radio channel per measurement link. Each estimated path is described by its directions of departure and arrival, delay, Doppler shift, and fully polarimetric complex path weights.

Single side mMIMO channel measurements over 100 MHz bandwidth at 3.75 GHz were performed in two German cities. In dense urban as well as urban/suburban environments, a total track length of about 20km has been measured. Multipath parameters by means of the high-resolution parameter estimator RIMAX are estimated and subsequently used to derive the statistics of large scale parameters and to allow a comparison to the statistics from standard channel model (3GPP, WINNER). While most of the parameters match quite well, for the angular spread at the base station (BS) partly larger deviations are observed. The correlation properties between the 32 dual polarized antenna patches of the BS antenna are investigated with respect to the antenna patch separation as well as to the distance between the BS and user equipment (UE).

Research on non-line-of-sight emitter localization relies almost exclusively on simulation data for the evaluation of proposed algorithms. This paper aims to encourage the use of measurements by introducing a setup based on off-the-shelf components that enables 1.5 ns synchronization accuracy and 2 cm ground truth accuracy for multiple distributed receivers and a mobile transmitter. Results from a measurement campaign in a 16 km2urban area are used to validate the system's performance.

We perform simultaneous vehicle-to-vehicle (V2V) multi-band double-directional measurements at 6.75 GHz, 30 GHz, and 60 GHz in a street canyon environment. We analyse both line-of-sight channels and those obstructed by vehicle blocker. For the different bands, we analyse delay spread, angular spread, vehicle blockage loss, and path loss. Finally, we discuss how the system aspects influence the radio channel.

Reliable and accurate multipath clustering results are essential to design and parameterize geometry based (stochastic) channel models proposed by organizations such as 3GPP, COST, WINNER and others. Clustering within wireless channel models assumes that multipath components arrive/depart with similar properties in the considered parameter domains. We propose a new approach combining tracking and initialization of the classic K-Means clustering algorithm. The results show a significantly improved consistency for cluster estimation, which subsequently allows for analyzing the lifetime of these clusters. Finally, we apply the proposed approach on two urban macro channel sounding datasets and compare them to the current 3GPP standard. We found that the angular parameters are rather similar to the standard whereas the cluster delay spreads and the number of rays per cluster differ significantly.

The small scale fading measurements at the 60 GHz frequency band are carried out to investigate the second-order statistics of a fading multipath cluster. The cluster is illuminated with different gain antennas (emulated beamforming gains). The analysis reveal that the measured channel impulse response (CIR) is approximately circular (or circularly symmetric) with correlated inphase (I) and quadrature (Q) components. These properties correspond to the sparse multipath channels and are different from the Rayleigh/Rician fading channels which assume that the I and Q components are mutually uncorrelated colored Gaussian variates. These differences prevent the application of the Rayleigh/Rice fading models in the intra-cluster multipath modeling.

Multidimensional characterization of outdoor urban macrocellular propagation channels is essential for the analysis and design of next-generation (5G and beyond) cellular massive MIMO (multiple-input-multiple-output) systems. Since most massive MIMO arrays will extend in two or three dimensions, an understanding of 3-D parameters (i.e., azimuth and elevation) of the multipath components (MPCs) is required. This paper presents an extensive measurement campaign for 3-D outdoor propagation channels in an urban macrocellular environment. Measurements were performed with a 20 MHz wideband polarimetric MIMO channel sounder centered at 2.53 GHz and MPCs were extracted using RIMAX-an iterative maximum likelihood algorithm. The physical propagation mechanisms of the observed discrete MPCs are explained in terms of waveguiding, over-the-rooftop propagation, and scattering by far-away objects. MPCs exhibit clustering in the temporal and spatial domains; both intra- and inter-cluster parameters and their relevant statistics are provided. We also extract diffuse MPCs, show that they can comprise a moderate portion of the overall energy, and provide a statistical characterization.

Large absolute channel bandwidths at millimeter wave (mmWave) frequencies and more directional antenna gains may lead to quasi-deterministic (less random) channel fading behavior. Randomness in the cross polarization discrimination (XPD) is an attribute related to the channel fading behavior. In narrow-band channels, it is usually modeled as a log-normal random variable. From channel modeling perspectives, XPD power level in a particular propagation environment and its degree of randomness are of fundamental interest. In this paper, XPD behavior is characterized as a function of bandwidth in 4 different propagation setups including line of sight (LOS), reflections from black board, a rough wall and double bounce reflections from both surfaces. It has been observed that in all cases, the coefficient of variation of XPD around its mean value reduces exponentially with an increase in channel bandwidth demonstrating an evolution towards quasi-deterministic channel behavior. Additionally, a 5-10 dB difference in XPD values has also been observed between narrow-band and UWB channels in the considered propagation setups.

In this paper, directional small scale fading measurements are used to extract the fading statistics of the received signal magnitude and the parameters of the underlying stochastic (Rayleigh/Rician) model. After that sum-of-cisoids (SOC) principle is used to model the deterministic samples (channel snapshots) of the stochastic model with a special focus on the number of sinusoids/scatterers and their weights. It has been established that theoretical and simulated results of the SOC fading channel simulator provide an excellent approximation of the measured received signal magnitude per cluster with a small number of sinusoids i.e. $N=4$.

This work presents measurements and characterizations of a 2.53 GHz wireless propagation channel for radio links in railway onboard applications. Wireless technologies have a great potential use in train control and structural health monitoring applications; however, in harsh propagation environments they suffer from severe signal degradation, including delay spread, deep fading and Doppler spread. The aim of this work is to analyze the signal propagation in railway environments by means of a measurement campaign at 2.53 GHz, taking into account antenna locations both inside and below the train car. Results from wideband and narrowband analysis are shown, focusing on delay spread, small-scale envelope fading distribution and Doppler spectrum.

The 3-D multiple-input multiple-output (3-D MIMO) systems have received great interest recently because of the spatial diversity advantage and capability for full-dimensional beamforming, making them promising candidates for practical realization of massive MIMO. In this paper, we present a low-cost test equipment (channel sounder) and post-processing algorithms suitable for investigating the 3-D MIMO channels as well as the results from a measurement campaign for obtaining elevation and azimuth characteristics in an outdoor-to-indoor (O2I) environment. Due to limitations in available antenna switches, our channel sounder consists of a hybrid switched/virtual cylindrical array with effectively 480 antenna elements at the base station. The virtual setup increased the overall MIMO measurement duration, thereby introducing phase drift errors in the measurements. Using reference antenna measurements, we estimate and correct for the phase errors during post-processing. We provide the elevation and azimuth angular spreads for the measurements done in an urban macro-cellular and urban micro-cellular environments, and study their dependence on the user equipment (UE) height. Based on the measurements done with UE placed on different floors, we study the feasibility of separating users in the elevation domain. The measured channel impulse responses are also used to study the channel hardening aspects of the massive MIMO and the optimality of the maximum ratio combining receiver.

3-dimensional Multiple-Input Multiple-Output (3D MIMO) systems have received great interest recently because of the spatial diversity advantage and capability for full-dimensional beamforming, making them promising candidates for practical realization of massive MIMO. For 3D MIMO system design, it is important to have full characterization of the 3D MIMO propagation channel, i.e., characterize both the elevation and azimuth characteristics of the wireless propagation channel, especially at the base station end. In this paper, we present first results from a measurement campaign for obtaining these characteristics. For those measurements we use a hybrid switched/virtual cylindrical array with 480 antenna elements at the base station (BS), and a switched array with 24 antenna elements at the user equipment (UE). We perform outdoor-to-indoor (O2I) channel measurements in an urban macro-cellular (UMa) and a micro-cellular (UMi) environments. We provide the elevation and azimuth angular spreads at the transmitter and receiver, and study their dependence on the UE height. With the increase in the UE height, the BS elevation spreads decreased from 1.24 deg to 1 deg and 1.15 deg to 0.78 deg respectively for UMa and UMi; the azimuth spreads remained approximately the same (7.5 deg). Based on the measurements done with the UE placed on different floors, we study the feasibility of separating users in the elevation domain. Users were separable in 44% and 54.17% scenarios respectively for the UMa and UMi environments.

Double-directional, ultra wideband dual-polarized channel measurements at 70 GHz have been carried out in a small-office environment. The aim of these measurements is to study the temporal, directional, and polarization properties of the channel for modelling purposes of the future wireless communication systems at mm-waves. A highly deterministic behaviour of the channel and the environment has been identified, as well as the limitations of only parameterizing channel models as WINNER for the new mm-wave channel models.

Existing fast antenna selection algorithms have either low performance gains or they are efficient only for the selection of particular size sub-matrices. Our motivation to the study of NP-Hard antenna selection problem is two-fold. First, we intend to propose an optimal algorithm that is equally efficient for each possible subset cardinality of the transmit and/or receive antennas. Second, different from any of the antenna selection algorithms proposed so far, our algorithm deterministically increases the strength of the singular values during the selection of each column of the selected matrix. This increase in the singular values is defined by a very tight bound. This bound has previously been used to analyze the efficiency of low rank approximation algorithms. Hence, our antenna selection procedure is as efficient as that of a best algorithm for matrix low rank approximations.

When a MIMO wireless channel matrix H is rank deficient, it is often required to select a submatrix Hp ϵ H such that the columns of Hp lie close to the optimal subspace that constructs H. Main motivation for the selection of Hp is to gain the same spectral efficiency benefits as that of H, but at a lower computational and RF hardware cost. In this contribution, we first present an analogy between the antenna and user selection problems. Secondly, a matrix volume maximization criterion that is applicable to both problems have been presented. We have proposed a low complexity deterministic algorithm for the selection of antennas/users such that the volume of Hp is maximum. We have shown that under particular channel propagation setup, smaller subsets can provide the same spectral efficiency as that of the full MIMO channel. We used a 3D extension of the WINNER channel model at center frequency 2.53 GHz to evaluate the performance of the proposed algorithm.

This work studies the dependency of MIMO performance figures on two characteristic multipath cluster parameters, the innercluster Angular Spread of Arrival (ASA) and the number of clusters. Both these parameters play a vital role in geometric based stochastic channel models as from the WINNER or COST families. Our motivation to the study these parameters is two-fold. First, we study their impact on the changing statistics of channel transmit and receive side correlations. Second, we will investigate their impact on the single user MIMO channel capacity. We present a detailed analysis for different MIMO order setups with both single as well as dual polarized antenna elements under Line-of-Sight (LOS) and Non-LOS (NLOS) propagation conditions. One key result is, that the number of clusters is more dominant than the angular spread of it. This empirical investigation considered a 3D extension of the WINNER channel model and the urban macro cell scenario at a center frequency of 2.53 GHz.

A wideband, fully polarimetric and directional radio channel sounding campaign conducted at 70 GHz is presented. Measurement site was chosen as an entrance hall, featuring femtocell size. Transmitter and receiver were placed according to an access-point scenario. Initial large-scale parameters like excess-delay, delay-spread and angular spread are derived for channel characterisation. It is not the paper's goal to describe a new channel model. The main focus is the identification of propagation effects and characteristics, which have to be considered in future modelling. It was found, that first more specular than diffuse components occur and second the channel is spatially sparse.

Owing to the limitation in bandwidth of currently used frequency bands, future fifth generation (5G) mobile networks will need to operate at higher frequencies. However, one important step in the research activities for the next generation of mobile networks is the broadband fully polarimetric analysis of the multipath propagation in dynamic single and multiuser scenarios under time-variant shadowing environments in millimetre- wave (mm-wave) channels. This paper presents a channel sounding campaign at 70 GHz in an urban outdoor scenario focusing on broadband channel characteristic at mmwave. For the measurements a novel dual-polarized (DP) ultrawideband (UWB) multi-channel sounder (DP-UMCS) architecture, developed at the TU Ilmenau for propagation measurements in cellular networks, was used to study the directional and polarization properties of the channel in view of the future wireless communication systems.

This study addresses the problem of the determining network performance metrics, the outage probability (pout) and the coverage area (C(φ)) more accurately, based on the distribution of shadow fading. Shadow fading characteristics are crucial in order to calculate of pout and C(φ) more properly. We investigate existing shadow fading models, lognormal, Gamma and Weibull distributions on empirical data and also propose a new lognormal mixtures model. We calculate pout and C(φ) according to the considered distributions and verify that shadow fading distribution needs to be accurately determined in order to obtain correct values of outage probability and coverage area.

This paper provides an overview of over-the-air (OTA) testing for next generation communication devices with special consideration of Car-to-Car (C2C) and Car-to-Infrastructure (C2I) communication. Existing state-of-the-art techniques, their merits, and limitations are discussed. We identify the requirements for the OTA test in virtual electromagnetic environment (OTAinVEE) for the C2C/C2I communication scenario, where interference emulation becomes a highly challenging task. We propose systematic test procedure and closed-loop OTA set-up applicable for such scenario. Since the main test challenge in C2C/C2I communication is the modeling of highly time variant channel, we discuss channel modeling concepts and propose a framework appropriate for such communication. The ongoing activities in Ilmenau towards simulation and testing for C2C/C2I communication is also briefly discussed.

Within this contribution the robustness and reliability of MIMO order (MOS) and antenna subset selection (AS) procedures has been studied. We considered AS for spatial multiplex (SM) systems, where the total power is distributed equally among selected antennas. MIMO channel data sets from a channel sounding campaign in an urban macro cell scenario have been used for advanced performance evaluation. At first, we studied correlation characteristics along various measurement tracks with single and dual polarized antenna configurations. We found that even under NLOS high correlation between antenna elements appears. Based on channel correlation at the transmit side and the receive SNR we discussed different methods for adaptive switching of the number of active RF modules and followed by optimized antenna subset selection (AS). Until a certain SNR threshold our novel low complex proposals perfectly follow the known algorithms from literature.

In wireless communication systems, dual-polarized (DP) instead of single-polarized (SP) multiple-input multiple-output (MIMO) transmission is used to improve the spectral efficiency under certain conditions on the channel and the signal-to-noise ratio (SNR). In order to identify these conditions, we first propose a novel channel model for DP mobile Ricean MIMO channels for which statistical channel parameters are readily obtained from a moment-based channel decomposition. Second, we derive an approximation of the mutual information (MI), which can be expressed as a function of those statistical channel parameters. Based on this approximation, we characterize the required SNR for a DP MIMO system to outperform an SP MIMO system in terms of the MI. Finally, we apply our results to channel measurements at 2.53 GHz. We find that, using the proposed channel decomposition and the approximation of the MI, we are able to reproduce the SNR values above which DP MIMO systems outperform SP MIMO systems.

Dual-polarized (DP) multiple-input multiple-output (MIMO) systems are known to be beneficial in terms of the spectral efficiency under certain conditions on the channel and the signal-to-noise ratio (SNR). In order to assess under which conditions DP antenna setups are advantageous over single-polarized (SP) antenna setups, an accurate yet analytically tractable modeling of such channels is a necessary but challenging task. We propose a novel channel model for DP mobile Ricean MIMO channels for which the statistical channel parameters are readily obtained from a moment-based channel decomposition. An approximate evaluation of the mutual information (MI), expressed as a function of the statistical channel parameters of the proposed channel model, is derived. This approximation allows to assess when it is beneficial in terms of the MI to switch from an SP to a DP setup. Finally, we evaluate the MI for selected SP and DP setups based on channel measurements at 2.53 GHz. We find that the DP setup only provides an improvement in terms of the MI in medium- to high-K-factor scenarios above a certain SNR. The approximate evaluation of the MI is able to accurately reproduce the SNR at which one should switch from an SP to the DP setup.

We propose a general channel model for mobile Ricean multiple-input multiple-output (MIMO) channels, which is characterized by parameters that are readily obtainable from measurements. To this end, a moment-based channel decomposition is derived. For the case of statistical channel state information (CSI) at the transmitter (TX) and instantaneous CSI at the receiver, we derive an approximation of the achievable rate, i.e., the mutual information (MI), which is only a function of the channel parameters of the proposed channel model and thus gives insight into the parameters that influence the MI. Finally, we evaluate the MI for a 4 × 4 MIMO system based on channel measurements at 2.53 GHz for two low-complexity TX strategies, i.e., a beamforming (BF) and a spatial multiplexing (SM) strategy. We find that the proposed channel model and the approximate evaluation of the MI are both accurate for realistic signal-to-noise ratio (SNR) values. The approximate evaluation is able to reproduce crossing points between the MI of the considered TX strategies; it thus reflects the SNR at which one should switch from the BF to the SM strategy.

The extension of multiple-input multiple-output (MIMO) systems to the polarization domain is known to have potential benefits in terms of the spectral efficiency. It is thus of importance to understand how the channel influences the spectral efficiency, e.g., when a dual-polarized (DP) antenna setup should be favored over a single-polarized (SP) one. In this work, we study the achievable rate, i.e., the sum mutual information (MI) of all transmitted streams, over DP MIMO channels with linear receivers. We derive an approximation of the sum MI with a linear minimum mean squared error (LMMSE) or a zero forcing receiver which is an explicit function of statistical channel parameters. The evaluations of selected 4×4 SP and DP MIMO setups are based on channel measurements performed at 2.53 GHz in an urban macrocell scenario. The results reveal that DP antenna setups can yield substantial gains in the sum MI on links with high K-factors and high signal-to-noise ratios (SNRs). Moreover, the degradation in the sum MI with two streams due to the use of an LMMSE receiver is found to be small, especially for the DP antenna setup. The approximate evaluation of the sum MI is able to reproduce the SNR threshold region in which a second transmitted stream should be activated or one should switch from an SP to a DP antenna setup.

Interference is one of the major bottlenecks in current cellular networks. A realistic evaluation of the achievable performance in interference-limited systems based on measured channels is thus necessary; however, only few results are known from literature. We evaluate the achievable performance in a cellular network with inter-cell interference based on measured channels in an urban macrocell scenario at 2.53 GHz. To this end, the mutual information is introduced as an appropriate performance measure over fast and slow fading channels that are non-stationary but doubly underspread. We discuss appropriate channel normalizations and the limitations of an evaluation based on sequential measurements. Moreover, we analyze the accuracy of an approximate but commonly used evaluation of the mutual information. A second-order multivariate Taylor series expansion reveals the signal and interference contributions to the approximation error. We find that the approximation is accurate in realistic ICI scenarios.

Channel sounding, channel modeling and their parameter extraction in particular considering MIMO configurations, plays an important role for todays realistic wireless system design and evaluation. The analysis of the gathered channel sounding data has to match the specifics in the measurement system configuration. Within this contribution directional antenna arrays are used at both sides of the measured link. Furthermore, the measurement system applies automatic gain control between subsequent MIMO snapshots and additionally within the MIMO matrix. Both features lead to improved measurement accuracy. A new extension of existing power and delay domain analysis procedures considering the automatic gain control within the MIMO matrix is introduced and evaluated. The results show that delay spread and K-factor are more affected, while shadow fading and cross polarization ratios are almost not.

Extensive analysis of channel measurement data for the investigation of new channel models plays a fundamental role in designing and evaluating todays wireless communication systems. Besides the knowledge of the parameters and their distribution functions, the cross correlation between them is of great interest and can be exploited for more sophisticated channel simulations. In this contribution the cross correlation characteristics of the large scale parameters (LSP) in the power and delay domain are investigated for different parameter estimation procedures (taking the spatial filtering due to directional antennas into account or neglecting it), for various distance ranges between base station (BS) and mobile station (MS) as well as for different antenna heights.

The joint characterization of the multiple links becomes important for mesh topologies, relaying, distributed antennas, cooperative transmission, virtual MIMO etc. For that purpose simultaneous measurements are needed. Since a suited measurement setup requires multiple channel sounders, a very few of such campaigns have been conducted. A single-sounder approach can be considered as an attractive, less expensive alternative as long as environment stationarity can be insured between consecutive measurement runs. This contribution investigates the variability of large-scale parameters, such as delay and directional spreads, derived from measurements at 2.53 GHz in an outdoor macro-cell scenario. A mobile receiver has been moved twice over the same track whereas the transmitter has been fixed. The large-scale parameters are estimated as averages within local stationarity regions corresponding to areas with a constant multi-path structure. The observed differences between two large-scale parameter sets are used to evaluate stationarity of the outdoor environment between repeated measurements. The reasonably low decorrelation levels have indicated that large-scale characterization of multi-link configuration can be performed sequentially with single sounding device.

A common simplification in the treatment of random linear channels is the wide-sense stationary and uncorrelated scattering (WSSUS) assumption. For wireless channels, this assumption is, however, only fulfilled in an approximative sense inside local time-frequency regions. Since algorithms in wireless digital communications often rely on knowledge of second order statistics of the channel, it is important to know the size of local quasi-stationarity regions. Thus, we determine quasi-stationarity regions in distance for an urban macrocell scenario. We observe that, based on the chosen measure and in our specific scenario, the time-frequency properties are dominant compared to the spatial properties in defining the size of quasi-stationarity regions. Furthermore, we find that in some cases the quasi-stationarity regions strongly depend on the mobile terminal orientation.

A common simplification in the treatment of random linear channels is the assumption of stationarity of the channel in time. The wireless channel is, however, known to be inherently non-stationary. We detail a methodology for non-stationarity analysis from an algorithmic perspective. For the determination of local quasi-stationarity regions, we consider a multi-link downlink scenario where multiple base stations use transmit beamforming to concurrently transmit to a single mobile terminal per time slot. We obtain an algorithm-specific measure, i.e., the signal-to-interference-plus-noise ratio (SINR) degradation, with which we evaluate local quasi-stationarity regions. Furthermore, we relate and compare the SINR degradation to the correlation matrix distance (CMD). In an urban macrocell scenario relevant to 3GPP Long Term Evolution (LTE), we find that the resulting local quasi-stationarity distances show the same trends, but that the CMD overestimates the average distances for our system model.

This paper presents results of wide band channel measurements at 2.53 GHz for a representative urban macro cell environment in Ilmenau, Germany. The extensive channel sounding campaign covered the MIMO radio links from 22 mobile tracks to 3 different base stations and 1 relay station. The results presented in this paper provide insight into the large scale parameter analysis of the power, delay domain, including the transmission loss and the statistical distributions of the shadow fading, narrowband k-factor and delay spread. Large scale parameters from angle domain (azimuth and elevation) are derived based on the high resolution multipath parameter estimation (RIMAX). Furthermore the cross correlation of these parameters are investigated and compared to state-of-the-art channel models as from the IST-WINNER.

Novel channel models as from COST 273 and IST-WINNER projects are models to evaluate the performance of multi-antenna concepts under link-level and system-level. For consistent performance evaluation the channel models needed to be parameterized by multipath parameters based on measurements. It seems these parameters can be grouped into geometrically co-located paths, so called clusters. The reliability and reproducibility of the estimated parameter groups, depend inter alia on the decision criterions, initialization and the chosen cluster algorithm itself. In this paper the focus is to analyse the performance of different clustering algorithms and initialization stages. Furthermore an improved initialization approach is presented.

Interdependences of radio-channel model parameters, being observed in some measurement data, should be reproduced by the model. For that purpose the statistical correlation is often used. From the same wideband multiple-input and multiple- output (MIMO) channel data, estimated correlation between large-scale propagation parameters (e.g. delay spread and shadow fading) could be different due to non-uniqueness of post-processing procedure. In this paper, through examining a set of measurement data, we studied the impacts of differently parameterized post-processing procedures of measurement data on the auto- and cross-correlation properties of large scale parameters. We focus on the single parameter in postprocessing procedures: different margins of noise cutting level. The measurement data are gathered in a public hotspot bridge-to-car highway LOS scenario in Ulm, Germany.

The IST-WINNER channel model (WIM) offers a complete channel model description in a sense of large-scale as well as small-scale effects in MIMO radio-channel for B3G system designs. This paper proposes the extension of 1D regular array structures being currently supported within WIM (uniform linear array - ULA) to arbitrary 3D antenna arrays. Arbitrary antenna structures are necessary for both modelling and validation purposes since antenna arrays define the spatial dimension of the radio-channel. General 3D antenna array description also embeds polarization concepts that are becoming important for modelling of 3D rotation of antenna array. In this paper two different strategies of using 3D antenna arrays in channel model simulations are proposed and discussed. Both methods are compared in terms of the computational complexity and their suitability for the current WIM channel model implementation.

This paper is summarizing and comparing properties of channel models used for Beyond-3G (B3G) MIMO simulations: 3GPP spatial channel model (SCM), its extension (SCME), and models developed by WINNER. Compared models are offering complete channel model description in a sense of large-scale as well as small-scale effects in MIMO radio-channel. WINNER targeted model was supposed to provide reliable tool for estimation of system performance, covering frequencies up to 5 GHz and bandwidths of 100 MHz in different types of environment. Since SCM was originally proposed for 2 GHz range and 5 MHz bandwidth, certain extensions (SCME) were necessary. However, SCME performance was restricted since it has been design as backward compatible with SCM. That was the motivation to start using the new WINNER generic channel model, where model parameters are extracted from channel-sounding measurements covering targeted frequency range and bandwidth. This paper describes all important differences and compares features and performances of the models.

This work presents a spatial channel model developed within the EC WINNER project. The channel model is mainly based on double-directional measurement campaigns carried out in the 5 GHz ISM band with bandwidths of up to 120 MHz. The model is based on a unified structure for indoor and outdoor environment. It covers 6 different propagation scenarios, namely indoor small office, indoor hall, urban microcell, urban macrocell, suburban macrocell, and rural environment. Both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation conditions are modeled

This paper investigates the effects of impulse noise on the performance of multidimensional parity check codes (MDPC) in additive white Gaussian noise and Rayleigh fading channels. The Bhattacharya upper bound is derived for impulsive noise and is found to closely match with the simulation results. It is observed that impulse noise can degrade the bit error rate performance by several dBs. Further, the use of incorrect impulse noise model in the receiver decoding algorithm is found to cause severe penalty in fading channels. Our results also show that MDPC codes outperform traditional convolutional codes in impulsive noise channels. The performance of MDPC codes is found to be slightly inferior to turbo codes, when the latter uses slightly lower code rate and higher complexity. The capacity limits for impulsive noise channels are also calculated

Convergence properties of frequency domain turbo equalization with multilevel bit-interleaved coded modulation (MLBICM) and bit-interleaved coded modulation (BICM) are studied in measured quasi-static fading channels by the means of semi-analytical convergence analysis. Spatial channel parameters are matched to the reached mutual information on a per-measurement basis and trends in the behavior of the equalizer are obtained, when the channel characteristics, in terms of transmit and receive side azimuth spreads, change. Robust convergence of frequency-domain turbo equalization combined with multilevel BICM is demonstrated through the convergence analysis. Three channel codes are evaluated in the measurement-based simulation showing the effects of outer code selection

A parametric modeling approach for multiple input multiple output (MIMO) radio channels is introduced that is based on measured data. The MIMO measurement principle can be effectively exploited to estimate the propagation direction of any significant path at both ends of the wireless link simultaneously. From the estimated parameter sets a precise reconstruction of the multidimensional wave field in the aperture domains of time, frequency and space is possible. This enables various analyses and simulations of MIMO transmission links in a very realistic way.