Sana Salous

An adaptive geometry-based stochastic model for non-isotropic MIMO mobile-to-mobile channels

In this paper, a generic and adaptive geometrybased stochastic model (GBSM) is proposed for non-isotropic multiple-input multiple-output (MIMO) mobile-to-mobile (M2M) Ricean fading channels. The proposed model employs a combined two-ring model and ellipse model, where the received signal is constructed as a sum of the line-of-sight, single-, and doublebounced rays with different energies. This makes the model sufficiently generic and adaptable to a variety of M2M scenarios (macro-, micro-, and pico-cells). More importantly, our model is the first GBSM that has the ability to study the impact of the vehicular traffic density on channel characteristics. From the proposed model, the space-time-frequency correlation function and the corresponding space-Doppler-frequency power spectral density (PSD) of any two sub-channels are derived for a non-isotropic scattering environment. Based on the detailed investigation of correlations and PSDs, some interesting observations and useful conclusions are obtained. These observations and conclusions can be considered as a guidance for setting important parameters of our model appropriately and building up more purposeful measurement campaigns in the future. Finally, close agreement is achieved between the theoretical results and measured data, demonstrating the utility of the proposed model.

Spectrum Occupancy Statistics and Time Series Models for Cognitive Radio

While dedicated spectrum occupancy monitoring provides vital information for frequency planning and management, it usually cannot tell the common properties in spectrum occupancy. As a complement, the models approach can be used to describe and compare the occupancy situations under similar conditions. Time series analysis has been applied to modeling the radio spectrum occupancy. This paper categorizes different time series models to different occupancy patterns. Occupancy analysis of the Global System for Mobile communications (GSM) band is given as an example.

Millimeter-Wave Propagation: Characterization and modeling toward fifth-generation systems. [Wireless Corner]

The World Radiocommunication Conference 2015 (WRC-15) identified a number of frequency bands between 24 and 86 GHz as candidate frequencies for future cellular networks. In this article, an extensive review of propagation characteristics and challenges related to the use of millimeter wave (mm-wave) in future wireless systems is presented. Reference to existing path-loss models including atmospheric and material attenuation in recommendations of the International Telecommunication Union (ITU) in Geneva, Switzerland, is given, and the need for new multidimensional models and measurements is identified. A description of state-of-the-art mm-wave channel sounders for single and multiple antenna measurements is followed by a discussion of the most recent deterministic, semideterministic, and stochastic propagation and channel models. Finally, standardization issues are outlined with recommendations for future research.

Medium- and Large-Scale Characterization of UMTS-Allocated Frequency Division Duplex Channels

A dual-band sounder is used in both trolley and van measurements in the dense urban environment of Manchester city center to characterize the uplink (1920-1980 MHz) and downlink (2110-2170 MHz) frequency-division duplex (FDD) channels allocated to third-generation (3G) mobile radio systems. The data are analyzed with 60- and 5-MHz resolutions, as used for 3G wideband code-division multiple-access systems. Root-mean-square (rms) delay spread and 15-dB widths of mainly temporally averaged delay profile are presented either as cumulative distribution functions (cdfs) for each individual frequency band or as histograms of the difference between uplink and downlink on a local area basis. It was found that the histograms show larger differences between the two bands than the individual cdf and that the differences between the FDD channels are more pronounced on circumferential routes and shadowed locations. Correlations of rms delay spread with excess path loss and distance are on the order of 0.5 and 0.4, respectively.

Wideband MIMO Channel Sounder for Radio Measurements in the 60 GHz Band

Applications of the unlicensed 60 GHz band include indoor wireless local area networks, outdoor short range communications and on body networks. To characterize the radio channel for such applications, a novel digital chirp sounder with programmable bandwidths up to 6 GHz with switched two transmit channels and two parallel receive channels for multiple-input multiple-output (MIMO) measurements was realized. For waveform durations of 819.2 μs, Doppler measurements can be performed up to 610 Hz for the single transmit and two receive configuration or 305 Hz for MIMO measurements. In this paper, we present the architecture of the sounder and demonstrate its performance from back to back tests and from measurements of rms delay spread, path loss and MIMO capacity in an indoor and an outdoor environment. For 20 dB threshold, the rms delay spread for 90% of the measured locations is estimated at 1.4 ns and 1 ns for the indoor and outdoor environments, respectively. MIMO capacity close to the iid channel capacity for 2 by 2 configuration is achieved in both environments.

Channel sounding for high-speed railway communication systems

High-speed railway (HSR) communications have recently attracted much attention due to some specific railway needs, such as passenger experience services, business process support services, and operational data and voice services. The HSR radio channel, as a basis for the design of HSR communication systems and the evaluation of HSR communication technologies, has not yet been sufficiently investigated. This article focuses on radio channel sounding techniques for future HSR communication systems. Emphasis is placed on the fundamental features of measuring the HSR channel, and a review of the state of the art in HSR channel measurements is given. We also propose a novel LTE-based HSR channel sounding scheme and present results from our own measurement campaigns.

Through-The-Wall Detection With Gated FMCW Signals Using Optimized Patch-Like and Vivaldi Antennas

This paper presents the design and optimization of patch-like antennas for through-the-wall imaging (TTWI) radar applications in the frequency range 0.5-2 GHz. A basic antenna configuration is analyzed and modified through an optimization aiming at reducing the size of the antenna and focusing the radiated power in a single lobe to be directed toward the wall and the targets to be detected. Both the basic and the optimized antennas have been manufactured and tested. The optimized patch antennas and a conventional Vivaldi antenna have been successfully used in the frequency-modulated interrupted continuous wave (FMICW) radar system developed at Durham University. Results of a novel wall-removal technique for TTWI using numerical simulations and measurements aimed at the detection of stationary targets and people are presented.

Low probability of intercept-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems

In this paper, we investigate the problem of low probability of intercept (LPI)-based adaptive radar waveform optimization in signal-dependent clutter for joint radar and cellular communication systems, where the radar system optimizes the transmitted waveform such that the interference caused to the cellular communication systems is strictly controlled. Assuming that the precise knowledge of the target spectra, the power spectral densities (PSDs) of signal-dependent clutters, the propagation losses of corresponding channels and the communication signals is known by the radar, three different LPI based criteria for radar waveform optimization are proposed to minimize the total transmitted power of the radar system by optimizing the multicarrier radar waveform with a predefined signal-to-interference-plus-noise ratio (SINR) constraint and a minimum required capacity for the cellular communication systems. These criteria differ in the way the communication signals scattered off the target are considered in the radar waveform design: (1) as useful energy, (2) as interference or (3) ignored altogether. The resulting problems are solved analytically and their solutions represent the optimum power allocation for each subcarrier in the multicarrier radar waveform. We show with numerical results that the LPI performance of the radar system can be significantly improved by exploiting the scattered echoes off the target due to cellular communication signals received at the radar receiver.

The design of linear phase FIR filters using the IDFT

The paper presents a comprehensive set of equations for specifying the transfer function of linear phase finite-impulse response (LPFIR) filters. A procedure for designing the eight possible LPFIR filters (symmetric and anti-symmetric, even and odd length, type 1 and type 2 filters), using the inverse discrete Fourier transform (IDFT) is described. This technique can be equally applied to the window method and the frequency sampling method.

Frequency-Modulated Interrupted Continuous Wave as Wall Removal Technique in Through-the-Wall Imaging

Undesired wall reflections in through-the-wall imaging can mask the return from actual targets and saturate and block the receiver. We propose frequency-modulated interrupted continuous wave (FMICW) signals as a novel wall removal technique and validate its effectiveness through numerical simulations and experiments performed using a radar system built for the purpose. FMICW waveforms appear to mitigate wall reflections and benefit the through-wall detection of stationary targets and of people moving or breathing behind different kinds of wall.