Ahmed M. Al-Samman

Statistical Modelling and Characterization of Experimental mm-Wave Indoor Channels for Future 5G Wireless Communication Networks.

This paper presents an experimental characterization of millimeter-wave (mm-wave) channels in the 6.5 GHz, 10.5 GHz, 15 GHz, 19 GHz, 28 GHz and 38 GHz frequency bands in an indoor corridor environment. More than 4,000 power delay profiles were measured across the bands using an omnidirectional transmitter antenna and a highly directional horn receiver antenna for both co- and cross-polarized antenna configurations. This paper develops a new path-loss model to account for the frequency attenuation with distance, which we term the frequency attenuation (FA) path-loss model and introduce a frequency-dependent attenuation factor. The large-scale path loss was characterized based on both new and well-known path-loss models. A general and less complex method is also proposed to estimate the cross-polarization discrimination (XPD) factor of close-in reference distance with the XPD (CIX) and ABG with the XPD (ABGX) path-loss models to avoid the computational complexity of minimum mean square error (MMSE) approach. Moreover, small-scale parameters such as root mean square (RMS) delay spread, mean excess (MN-EX) delay, dispersion factors and maximum excess (MAX-EX) delay parameters were used to characterize the multipath channel dispersion. Multiple statistical distributions for RMS delay spread were also investigated. The results show that our proposed models are simpler and more physically-based than other well-known models. The path-loss exponents for all studied models are smaller than that of the free-space model by values in the range of 0.1 to 1.4 for all measured frequencies. The RMS delay spread values varied between 0.2 ns and 13.8 ns, and the dispersion factor values were less than 1 for all measured frequencies. The exponential and Weibull probability distribution models best fit the RMS delay spread empirical distribution for all of the measured frequencies in all scenarios.

A comprehensive review on coordinated multi-point operation for LTE-A

Abstract With the enormous increase in application demands and users data rate, high Quality of Service (QoS) has attracted significant attention from the mobile operators and academia in the past few years. Coordinated Multi-Point (CoMP) operation system provides a valid solution to enhanced throughput and coverage performance by reducing the interference, especially for cell-edge users. In CoMP operation, multiple Base Stations (BS) coordinate with each other in such a way that the users information signal from neighboring evolved Node B (eNB) reduces interference or even can be combined to improve received signal quality. CoMP transmission is depending on the sharing coordination information via backhaul links, usually, consist of users feedback that explains channel condition. This paper provides a brief vision into the CoMP technology including its architecture, sets, and promising approaches that can be employed in the future network. It discussion extends to the deployment scenarios in which CoMP schemes will likely be most beneficial in the modern backhaul designs available today. The study also covers the most well-known CoMP types such as coordinated scheduling and beamforming, joint transmission and dynamic point selection in detail along with its issues and current possible solutions. Most of the ideas presented are presently being studied and may diverge throughout the standardization work. In addition, a range of practical issues is identified and addressed in the deployment of CoMP in Heterogeneous Network (HetNet) and Multiple Input Multiple Output (MIMO) system, such as backhaul traffic, synchronization, and feedback design. This article provides an insight into the current research problem and also suggested the most challenging research gaps that may be useful for future research. It is shown that CoMP leads to both network throughput and capacity expansion in Long Term Evolution Advanced (LTE-A) network and can significantly provide more enhancements in spectrum efficiency and network performance gain with better cooperative coordination strategies.

Experimental characterization of an UWB channel in outdoor environment

An experimental characterization of the ultrawide-band (UWB) channel in an outdoor environment over the frequency range from 3.1 GHz to 5.3 GHz is presented in this paper. The measurements are taken in time domain and line-of-sight (LOS). The statistical model for the delay spread is characterized and there is no correlation between delay spread and transmitter receiver distance. Different statistical distributions for the delay spread are investigated. The reflective nature of this environment is shown in the Ricean K-factor.

Window-based channel impulse response prediction for time-varying ultra-wideband channels

This work proposes channel impulse response (CIR) prediction for time-varying ultra-wideband (UWB) channels by exploiting the fast movement of channel taps within delay bins. Considering the sparsity of UWB channels, we introduce a window-based CIR (WB-CIR) to approximate the high temporal resolutions of UWB channels. A recursive least square (RLS) algorithm is adopted to predict the time evolution of the WB-CIR. For predicting the future WB-CIR tap of window wk, three RLS filter coefficients are computed from the observed WB-CIRs of the left wk−1, the current wk and the right wk+1 windows. The filter coefficient with the lowest RLS error is used to predict the future WB-CIR tap. To evaluate our proposed prediction method, UWB CIRs are collected through measurement campaigns in outdoor environments considering line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Under similar computational complexity, our proposed method provides an improvement in prediction errors of approximately 80% for LOS and 63% for NLOS scenarios compared with a conventional method.

Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands

This paper presents millimeter wave (mmWave) measurements in an indoor environment. The high demands for the future applications in the 5G system require more capacity. In the microwave band below 6 GHz, most of the available bands are occupied; hence, the microwave band above 6 GHz and mmWave band can be used for the 5G system to cover the bandwidth required for all 5G applications. In this paper, the propagation characteristics at three different bands above 6 GHz (19, 28, and 38 GHz) are investigated in an indoor corridor environment for line of sight (LOS) and non-LOS (NLOS) scenarios. Five different path loss models are studied for this environment, namely, close-in (CI) free space path loss, floating-intercept (FI), frequency attenuation (FA) path loss, alpha-beta-gamma (ABG), and close-in free space reference distance with frequency weighting (CIF) models. Important statistical properties, such as power delay profile (PDP), root mean square (RMS) delay spread, and azimuth angle spread, are obtained and compared for different bands. The results for the path loss model found that the path loss exponent (PLE) and line slope values for all models are less than the free space path loss exponent of 2. The RMS delay spread for all bands is low for the LOS scenario, and only the directed path is contributed in some spatial locations. For the NLOS scenario, the angle of arrival (AOA) is extensively investigated, and the results indicated that the channel propagation for 5G using high directional antenna should be used in the beamforming technique to receive the signal and collect all multipath components from different angles in a particular mobile location.

Time dispersion analysis and capacity for ultra wideband channel in indoor environment

In this paper, the ultra wideband (UWB) channel characterisation based on time dispersion analysis is presented. The UWB channel behaviour is different from narrowband and wideband channels due to the large bandwidth, which is the major concern for the channel capacity. In addition, the large bandwidth leads to increased channel variation. The channel characteristics and analysis are important to track the behaviour of UWB channel. The channel measurements were conducted in an indoor environment for UWB system in line-of-sight (LOS) scenario. Time dispersion parameters, namely, root mean squared (RMS) delay spread and mean excess (MN.EX) delay, are analysed based on these measurements. The effectiveness of multipath components is also investigated by means of the multipath gain (MG) and channel capacity. The presented results show that there is a correlation between RMS delay spread and transmitter-receiver (TX-RX) separation distance. The results also show that the best fitting for the RMS delay spread is the Weibull model and the maximum MG is 4.1 dB, which is calculated at the maximum TX-RX separation distance. The channel capacity of multipath components outperforms the capacity of the LOS path by 0.3 bps/Hz.

Path loss model for outdoor environment at 17 GHz mm-wave band

This paper presents the path loss model for 17 GHz mm-Wave frequency spectrum. The millimeter-wave spectrum has been proposed for future high speed 5G cellular systems with large bandwidth requirement. Since this proposal, propagation studies characterizing and investigating the potential of mm-Wave spectrum have been aggressively performed. This work conducts measurement campaign to derive a path loss models for outdoor environment in line-of-sight (LOS) scenarios at 17 GHz mm-Wave frequency spectrum. The derived models are based on the log-normal shadowing model. The path loss exponent for the derived path loss models is 2.3, which indicates that the chosen outdoor environment is an open environment like free space. Comparison between the values of path loss provided by the measured data, the derived path loss model and the free space model is made. The differences between the path loss value from the measured data and the derived path loss model is 7dB, while 13 dB differences is found when comparing the measured data and the free space loss model.

Path loss model in outdoor environment at 32 GHz for 5G system

This paper presents the outcome of outdoor measurement campaigns for 5G system at 32 GHz, which were conducted at the University Technology Malaysia (UTM), Kuala Lumper branch. Featuring measurement results of line-of-sight (LOS) for Co- and Cross antenna polarizations using highly direction horn antennas at transmitter and receiver are investigated for large scale path loss models. For non-line of sight (NLOS) case study, the horn and omni directional antennas are used at the receiver side for comparing horn-horn and horn-omni cases. Based on the measured data, the close-in free space and floating intercept path loss models are investigated for a unique environment. The results show that the path loss exponent range is 3.4–6.7 based on different antenna configuration for LOS and NLOS scenarios. This work founds that the FI path loss model is not suitable for NLOS scenario at such particular environment.

Channel characterization for indoor environment at 17 GHz for 5G communications

The increasing demand for the extremely-high capacity and connectivity in wireless communication systems has motivated the researchers to explore the fifth-generation (5G) mobile communication. Owing to the wide bandwidth demand to increase the capacity, current spectrum bands below 6 GHz allocated for cellular mobile communication are congested and insufficient to support the services envisioned for 5G. Therefore, extensive on-going studies are investigating the feasibility to implement 5G systems at frequency above 6 GHz. In this paper, the propagation path loss at 17 GHz in indoor environment is characterized through series of continuous-wave channel measurements. Measurement results in typical Malaysian indoor propagation environment for both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios are presented.

4G channel characterization for indoor environment at 2.6 GHz

In this paper we presents the penetration losses measurement for regular building at 2.6 GHz Long Term Evolution (LTE) cellular communication. The building penetration losses was measured in indoor environment at Wireless Communication Centre Building, characterizes the propagation of radio channel throughout the three type of walls; interior, exterior and plasterboard wall. The TX-RX separation and the type of wall contributed to variation of the penetration losses. Furthermore, the interior furniture, for instance wooden door or tinted glass will give various characterizations on radio channel. The aim of the work is to evaluate the performance of radio channel penetration at 2.6 GHz in typical indoor office building environment.