Dual-slope Path Loss Model Research Articles

Dual-Slope Path Loss Model for Integrating Vehicular Sensing Applications in Urban and Suburban Environments.

The development of intelligent transportation systems (ITS), vehicular ad hoc networks (VANETs), and autonomous driving (AD) has progressed rapidly in recent years, driven by artificial intelligence (AI), the internet of things (IoT), and their integration with dedicated short-range communications (DSRC) systems and fifth-generation (5G) networks. This has led to improved mobility conditions in different road propagation environments: urban, suburban, rural, and highway. The use of these communication technologies has enabled drivers and pedestrians to be more aware of the need to improve their behavior and decision making in adverse traffic conditions by sharing information from cameras, radars, and sensors widely deployed in vehicles and road infrastructure. However, wireless data transmission in VANETs is affected by the specific conditions of the propagation environment, weather, terrain, traffic density, and frequency bands used. In this paper, we characterize the path loss based on the extensive measurement campaign carrier out in vehicular environments at 700 MHz and 5.9 GHz under realistic road traffic conditions. From a linear dual-slope path loss propagation model, the results of the path loss exponents and the standard deviations of the shadowing are reported. This study focused on three different environments, i.e., urban with high traffic density (U-HD), urban with moderate/low traffic density (U-LD), and suburban (SU). The results presented here can be easily incorporated into VANET simulators to develop, evaluate, and validate new protocols and system architecture configurations under more realistic propagation conditions.

MM-Wave HetNet in 5G and beyond Cellular Networks Reinforcement Learning Method to improve QoS and Exploiting Path Loss Model

This paper presents High density heterogeneous networks (HetNet) which are the most promising technology for the fifth generation (5G) cellular network. Since 5G will be available for a long time, previous generation networking systems will need customization and updates. We examine the merits and drawbacks of legacy and Q-Learning (QL)-based adaptive resource allocation systems. Furthermore, various comparisons between methods and schemes are made for the purpose of evaluating the solutions for future generation. Microwave macro cells are used to enable extra high capacity such as Long-Term Evolution (LTE), eNodeB (eNB), and Multimedia Communications Wireless technology (MC), in which they are most likely to be deployed. This paper also presents four scenarios for 5G mm-Wave implementation, including proposed system architectures. The WL algorithm allocates optimal power to the small cell base station (SBS) to satisfy the minimum necessary capacity of macro cell user equipment (MUEs) and small cell user equipment (SCUEs) in order to provide quality of service (QoS) (SUEs). The challenges with dense HetNet and the massive backhaul traffic they generate are discussed in this study. Finally, a core HetNet design based on clusters is aimed at reducing backhaul traffic. According to our findings, MM-wave HetNet and MEC can be useful in a wide range of applications, including ultra-high data rate and low latency communications in 5G and beyond. We also used the channel model simulator to examine the directional power delay profile with received signal power, path loss, and path loss exponent (PLE) for both LOS and NLOS using uniform linear array (ULA) 2X2 and 64x16 antenna configurations at 38 GHz and 73 GHz mmWave bands for both LOS and NLOS (NYUSIM). The simulation results show the performance of several path loss models in the mmWave and sub-6 GHz bands. The path loss in the close-in (CI) model at mmWave bands is higher than that of open space and two ray path loss models because it considers all shadowing and reflection effects between transmitter and receiver. We also compared the suggested method to existing models like Amiri, Su, Alsobhi, Iqbal, and greedy (non adaptive), and found that it not only enhanced MUE and SUE minimum capacities and reduced BT complexity, but it also established a new minimum QoS threshold. We also talked about 6G researches in the future. When compared to utilizing the dual slope route loss model alone in a hybrid heterogeneous network, our simulation findings show that decoupling is more visible when employing the dual slope path loss model, which enhances system performance in terms of coverage and data rate.

Performance analysis of coverage-centric heterogeneous cellular networks using dual-slope path loss model

Densifying the cellular networks has been largely considered as a promising solution in meeting the capacity demands of emerging cellular networks that have expeditiously transformed from voice-oriented to data-oriented. However, densifying the network infrastructure is like a double-edged sword; it on one hand helps in achieving the desired data rates but on the other hand, it degrades the network coverage. Owing to the disparity in transmit power of macro base stations (MBSs) and small BSs (SBSs), the SBSs located in the close proximity of MBSs have negligible coverage areas that not only overburden the macro tier but also cause excessive interference. In order to overcome these limitations, we propose to mute the SBSs that are located in the near-vicinity of MBSs to introduce a partial-correlation between the locations of the BS tiers. Meanwhile, to further enhance the coverage performance of these coverage-centric cellular networks, the traditional load balancing mechanism along with interference abating strategy is also employed in this paper. Nonetheless, it is also well-known in the literature that the usage of single-slope path loss model (PLM) leads to significant inaccuracies in evaluating the performance of dense cellular networks. Therefore, a more accurate PLM based on the dual-slope is adopted in this paper. Analytical expressions for the tier association and coverage probability are derived for a randomly chosen user using the tools from stochastic geometry and validated through simulations. The numerical results testify the improvement in network coverage due to the non-uniform deployment of SBSs and the joint consideration of load balancing and interference mitigation mechanisms.

In-building coverage of millimeter-wave wireless networks from channel measurement and modeling perspectives

To progress cost-effective deployment of millimeter-wave (mmWave) wireless networks for indoor users, the prediction of indoor-to-indoor (I2I) and outdoor-to-indoor (O2I) coverage based on field measurement studies is of great interest to the future generation mobile communication system. First, measurements in I2I and O2I scenarios, which have advantages in terms of achieving a fair comparison of channel characteristics across different mmWave bands and bandwidths, are performed. Next, the developed dual-slope path loss model with a break-point distance is found to well fit omnidirectional and directional measured I2I data, especially at 39.5 GHz, revealing that the transition from lit or shadow regions to totally blocked regions is abrupt. Combined with space-time propagation characteristics, the indoor blockage effect on path loss and angular spread is investigated, therein being essential for the design of beam-steering and tracking algorithms. Double-directional measurement results show that most dominant paths arrive along the line-of-sight path, and only a few in-building reflections can be detected in higher frequency bands. Based on the joint analysis of channel measurement and modeling results, several mmWave network design and in-building coverage enhancement insights are presented.

On the Coverage and Capacity of Ultra-Dense Networks With Directional Transmissions

We investigate the performance of a downlink ultra-dense network (UDN) with directional transmissions via stochastic geometry. Considering the dual-slope path loss model and sectored beamforming pattern, we derive the expressions and asymptotic characteristics of the coverage probability and constrained area spectrum efficiency (ASE). Several special scenarios, namely the physically feasible path loss model and adjustable beam pattern, are also analyzed. Although signal-to-interference-plus-noise ratio collapsing still exists when the path loss exponent in the near-field is no larger than 2, using strategies like beam pattern adaption, can avoid the decrease of the coverage probability and constrained ASE even when the base station density approaches infinity.

Uplink coverage probability and spectral efficiency for downlink uplink decoupled dense heterogeneous cellular network using multi-slope path loss model

Low powered node densification leading to dense and ultra dense heterogeneous networks is a feature of 5th generation cellular networks. With this densification, the nature of the link between the transmitter and receiver in the network requires even more accurate and reliable models. For performance analysis of such networks where the rates of signal loss over distance becomes a significant parameter, more accurate path loss models should be used when analyzing user equipment (UE) association probability, coverage probability and average spectral efficiency. In this paper, we have considered a two-tier dense heterogeneous cellular network incorporating downlink uplink decoupled technique and have derived generalized expressions for UE association probability, decoupled uplink coverage probability and decoupled uplink average spectral efficiency using multi-slope path loss model. This path loss model broadly incorporates the effects of physical environment on the distance-dependent path loss. For simulation purpose, we have compared network performance while considering single-slope and dual-slope path loss models. The derived analytical expressions have been validated through network simulations and found in good agreement. Through comparison, it has been found that the decoupled UE association probability and uplink coverage probability is higher when incorporating multi-slope path loss model as compared to single-slope path loss model while the decoupled uplink spectral efficiency is observed to be lower when incorporating dual slope path loss model.

Spectral Efficiency of Energy Harvesting Random Cognitive Radio Networks in Dual-slope Model

This research article evaluates the performance of an energy harvesting random cognitive radio network employing a dual-slope path-loss model in terms of spectral efficiency. It derives the mathematical expression of spectral efficiency by means of stochastic geometry for secondary receivers presen

Impact of Frequency Reuse and Flexible Cell Association on the Performance of Dense Heterogeneous Cellular Networks Using Dual-Slope Path Loss Model

Impact of Frequency Reuse and Flexible Cell Association on the Performance of Dense Heterogeneous Cellular Networks Using Dual-Slope Path Loss Model

Radio Propagation Model Considering Antenna Beam Tilt with Application to Small Cells

Antenna beam tilting techniques are commonly used to deploy small cells with reduced coverage compared than macrocells. This paper proposes a new statistical propagation model for small cells with electrical and mechanical antenna tilt. The proposed model combines the dual slope path loss model with the departure angle spread model for considering antenna beam tilt. The proposed departure angle spread model introduces a new parameter reflecting the azimuth spread of departure (ASD) angles in order to account for the change of transmit antenna gain by electrical and mechanical tilt. Through this approach, the antenna gain for each ray is separately computed by considering the transmit antenna beam pattern as well as the antenna beam tilt. We perform field tests to measure the receive signal power in the downlink of commercial Long-Term Evolution small cells with antenna tilt. Based on the measurement data, we find the statistically optimal ASD parameter using a grid search and calculate the antenna gain for each ray. Also, the overall transmit antenna gain is obtained by averaging antenna gains for multiple rays. To assess the accuracy of the proposed model, the estimation error is evaluated by comparing the measured receive signal power with the estimated value using a propagation model, and the performance of the proposed propagation model is compared with those of existing path loss models in terms of root mean square error deviation. Then, it is shown that the proposed model provides more accurate propagation estimation for small cells than existing models.

Resource Optimization in Multi-Tier HetNets Exploiting Multi-Slope Path Loss Model

Current resource allocation techniques in cellular networks are largely based on single-slope path loss model, which falls short in accurately capturing the effect of physical environment. The phenomenon of densification makes cell patterns more irregular; therefore, the multi-slope path loss model is more realistic to approximate the increased variations in the links and interferences. In this paper, we investigate the impacts of multi-slope path loss models, where different link distances are characterized by different path loss exponents. We propose a framework for joint user association, power and subcarrier allocation on the downlink of a heterogeneous network (HetNet). The proposed scheme is formulated as a weighted sum rate maximization problem, ensuring the users’ quality-of-service requirements, namely users’ minimum rate, and the base stations’ (BSs) maximum transmission power. We then compare the performance of the proposed approach under different path loss models with demonstrate the effectiveness of dual-slope path loss model in comparison to the single-slope path loss model. Simulation results show that the dual-slope model leads to significant improvement in network’s performance in comparison to the standard single-slope model by accurately approximating the path loss exponent dependence on the link distance. Moreover, it improves the user offloading from macrocell BS to small cells by connecting the users to nearby BSs with minimal attenuation. It has been shown that the path loss exponents significantly influence the user association lying across the critical radius in the case of the dual-slope path loss model.

Correction Terms of Ground and Water Reflection Surfaces for Perera’s Breakpoint Distance Model

Wireless localization techniques based on received signal strength require highly accurate prediction of path loss. This has led to revisit existing breakpoint distance models for path loss prediction. Dual-slope path loss models for line-of-sight propagation have been verified by many measurement campaigns. Breakpoint distance is the distance that separates the two different trends in path loss levels. Many prediction breakpoint distance models have already been proposed in literature. Perera’s breakpoint distance model has been verified with some of the published measurement results. In this work, we provide correction terms for ground and water reflection surfaces for both horizontal and vertical polarization. The correction terms generalize application of Perera’s model in terms of applicability ranges and RF propagation scenarios. The correction terms are based on analyzing and modeling of extracted patterns of prediction error.

Link connectivity under more realistic channel model for vehicle-to-vehicle communications

Since the antennas are very low in vehicle-to-vehicle V2V scenarios, the communication link is easily blocked by other vehicles. The shadowing effect caused by other vehicles has been ignored in most of the existing V2V channel models, and it is thus neglected in the system performance evaluation. By incorporating channel state transition with a measurement-based dual-slope path loss model, an obstacle-based model is presented in this paper for the V2V highway scenarios to capture the dynamic characteristics of radio channels, in the presence of other vehicles as moving obstacles. The joint effects of the radio environment and traffic flow on link connectivity are mainly investigated. The obstruction probability is represented, and the connectivity-related metrics are evaluated: inter-vehicle connectivity probability and link duration. All the analytical results are validated by extensive simulations under the measurement-based path loss model, and are also compared to the existing models.

SINR and Throughput Scaling in Ultradense Urban Cellular Networks

We consider a dense urban cellular network where the base stations (BSs) are stacked vertically as well as extending infinitely in the horizontal plane, resulting in a greater than two dimensional (2D) deployment. We use a dual-slope path loss model that is well supported empirically, wherein a “close-in” pathloss exponent $\alpha_0$ is used for distances less than a corner distance $R_c$ , and then changes to $\alpha_1 > \alpha_0$ outside $R_c$ . We extend recent 2D coverage probability and potential throughput results to $d$ dimensions, and prove that if the close-in path loss exponent $\alpha_0 , then the SINR eventually decays to zero. For example, $\alpha_0 \le 3$ results in an eventual SINR of 0 for all users in a 3D network, which is a troubling fact. We also show that the potential (i.e. best case) aggregate throughput decays to zero for $\alpha_0 . Both of these scaling results also hold for the more realistic case that we term 3D+, where there are no BSs below the user, as in a dense urban network with the user on or near the ground.