In beyond 5G (B5G), the higher directivity and attenuation make millimeter-wave (mmWave) very vulnerable to blockages that degrades the system performance. However, reconfigurable intelligent surface (RIS) is consider...
详细信息
In beyond 5G (B5G), the higher directivity and attenuation make millimeter-wave (mmWave) very vulnerable to blockages that degrades the system performance. However, reconfigurable intelligent surface (RIS) is considered as a key enabler for B5G applications to avoid the blockages effect. In this paper, to accurately model real-world behavior, we investigate a new analytical framework model for a RIS-aided wireless communication system with a random user deployment over Nakagami-$m$ fading channel where the user's position distributes according to random waypoint (RWP) model, to characterize the performance of the system, considering direct and indirect links. As a result, new expressions for end-to-end signal-to-noise ratio (SNR), coverage probability, and ergodic capacity (EC) are derived. The impact of different metrics such as: blockages density (lambda(b)), number of RIS reflecting elements (N), fading parameter at the indirect link (mR), and path loss parameter (alpha) has been studied to evaluate the system performance. The results provide valuable insights into the performance of the system under these metrics. The coverage probability is degraded by increasing the blockage density and path loss parameter as they hinder the signal propagation and limit the signal strength at the MU. For example, at -10 dB, the coverage probability is degrading from 8x 10(-2) for blockage density lambda(b)=3 Blockes/km(2) to 5x 10(-5) at lambda(b)=11 Blockes/km(2). On the other hand, increasing the number of RIS reflecting elements (N) and fading parameter (m(R)) at the indirect link, improves the coverage probability by enhancing the signal strength, reducing the effects of fading, and compensating for environmental challenges such as blockages. For example, the coverage probability, at -10 dB, increases from 3 x 10(-1) at number of reflecting elements N = 15 to 8x 10(-1) at N=40. As well, the increasing of N and m(R) can significantly boost the EC as the system can direct th
The performance of energy harvesting (EH)-enabled long-range (LoRa) networks is analyzed in this work. Specifically, we employ deep learning (DL) to estimate the coverage probability (Pcov) of the considered networks....
详细信息
Device-to-device (D2D) communication is a key technology in next-generation wireless networks to enhance spectrum resource utilization. The interference from the activated D2D links degrades the quality of service (Qo...
详细信息
Device-to-device (D2D) communication is a key technology in next-generation wireless networks to enhance spectrum resource utilization. The interference from the activated D2D links degrades the quality of service (QoS) provided to cellular users. In this work, we propose a location-based technique to tackle the interference caused by the D2D underlaying downlink cellular network. The devices operating in stationary and mobile modes are considered, with mobile devices modelled using a Gauss Markov mobility (GMM) model to simulate realistic user movement patterns. Initially, we present an interference mitigation approach that dynamically adjusts the guard zone (GZ) through power control to guarantee the required QoS for all users. A distance-based mode selection mechanism is proposed to enable the users to select their mode of communication based on different GZ regions. Furthermore, we derive the closed-form expressions of the average coverage probability for the cellular and D2D links under the proposed power control with guard zone (PC-GZ) scheme. Finally, extensive simulations confirm the efficacy of the proposed PC-GZ approach, illustrating a 15% increase in cellular coverage probability compared to the PC-ILA scheme in high D2D density scenarios.
This paper investigates the dense multi-user sparse code multiple access (SCMA) cellular networks, where base stations (BSs) and users are randomly deployed in a 3D space by using stochastic geometry tools. First, a m...
详细信息
This paper investigates the dense multi-user sparse code multiple access (SCMA) cellular networks, where base stations (BSs) and users are randomly deployed in a 3D space by using stochastic geometry tools. First, a method increasing the dimension of the assignment matrix is presented to provide massive connectivity in each cell. The random pattern of arrangement of non-zero elements access (RPA) policy is utilized to allocate the available SCMA resources. Then the coverage probability is characterized under the nearest-BS (NBS) association mechanism by developing a multi-user connectivity model based on the RPA policy and average connectivity ratio (ACR). A compact closed-form expression of the coverage probability and its approximation are derived by utilizing the Toeplitz matrix and finite sum of power series, respectively. We then extract the area potential spectral efficiency (APSE) based on the coverage probability, and provide new insights into the 3D dense multi-cell SCMA networks. Simulation results confirm the precision of the theoretical results and demonstrate the advantage of the SCMA scheme.
Expressions are derived for the coverage probability and average rate of both multi-usermultiple inputmultiple output (MU-MIMO) and single input multiple output (SIMO) systems in the context of a fractional frequency ...
详细信息
Expressions are derived for the coverage probability and average rate of both multi-usermultiple inputmultiple output (MU-MIMO) and single input multiple output (SIMO) systems in the context of a fractional frequency reuse (FFR) scheme. In particular, given a reuse region of 13 (FR3) and a reuse region of 1 (FR1) as well as a signal-to-interference-plus-noise-ratio (SINR) threshold S-th, which decides the user assignment to either the FR1 or FR3 regions, we theoretically show that: 1) the optimal choice of S-th which maximizes the coverage probability is S-th = T, where T is the target SINR required for ensuring adequate coverage, and 2) the optimal choice of Sth which maximizes the average rate is given by Sth = T', where T' is a function of the path loss exponent, the number of antennas and of the fading parameters. The impact of frequency domain correlation amongst the OFDM sub-bands allocated to the FR1 and FR3 cell-regions is analysed and it is shown that the presence of correlation reduces both the coverage probability and the average throughput of the FFR network. Furthermore, the performance of our FFR-aidedMU-MIMO and SIMO systems is compared. Our analysis shows that the (2 x 2) MU-MIMO system achieves 22.5% higher rate than the (1 x 3) SIMO system and for lower target SINRs, the coverage probability of a (2 x 2) MU-MIMO system is comparable to a (1 x 3) SIMO system. Hence the former one may be preferred over the latter. Our simulation results closely match the analytical results.
Uplink cellular networks are usually modeled using simple Wyner-type cellular models where interference is simplified as a single random variable, or via 2-D Poisson point process(PPP) theory, with mobile users either...
详细信息
Uplink cellular networks are usually modeled using simple Wyner-type cellular models where interference is simplified as a single random variable, or via 2-D Poisson point process(PPP) theory, with mobile users either scattered randomly or placed deterministically. These models are insufficient to evaluate performance in dense urban environments where a large number of small cells are installed. We take a fresh look at this problem using tools from 3-D PPP, and we develop a new general model based on 3-D space for uplink cellular networks. The main idea is modeling mobile users and small cells as two separate spatial PPPs. Under general assumptions, the uplink coverage probability can be easily evaluated through fast integral calculation. We compare our model to the traditional 2-D model and actual mobile user/small cell deployment, and we observe that the proposed model is more accurate and provides a closer bound of coverage probability.
In the disaster-hit areas where ground network infrastructure has been severely damaged, one challenging problem for multi-UAV-assisted disaster relief networks is how to improve the coverage probability of each UAV. ...
详细信息
In the disaster-hit areas where ground network infrastructure has been severely damaged, one challenging problem for multi-UAV-assisted disaster relief networks is how to improve the coverage probability of each UAV. On the basis of solving this problem, the second challenging problem is how to design a channel and power-beam allocation scheme to optimize system throughput while meeting spectrum-energy efficiency constraint. In this article, we first propose a new method for measuring single UAV coverage quality, which considers both the ratio of effective coverage time to single loop flight time and that of the ground terminals with effective coverage time to the total ground terminals. Then, we develop a set of new algorithms to take advantage of the uneven distribution of ground terminals, which can achieve the total coverage probability improvement and the reduction of deployment costs of UAVs. Finally, we formulate the second problem as Markov decision process (MDP) and develop a solution based on deep deterministic policy gradient (DDPG). Simulation results demonstrate the validity and superiority of our proposed solutions compared with other benchmark strategies in different perspectives.
In this letter, we consider a new large-scale communication scheme where randomly distributed backscatter nodes are involved as secondary users to primary transmitter and primary receiver pairs. The secondary communic...
详细信息
In this letter, we consider a new large-scale communication scheme where randomly distributed backscatter nodes are involved as secondary users to primary transmitter and primary receiver pairs. The secondary communication between a backscatter transmitter and a backscatter receiver introduces additional double fading channels and has a two-side effect to the primary communications. We derive the signal-to-interference-plus-noise ratio and signal-to-interference ratio based coverage probabilities for two network configuration scenarios.
The kappa- mu and eta - mu are general fading distributions, which model line-of-sight and non-line-of-sight propagation effects, respectively. In this work, expressions for the coverage probability and average rate w...
详细信息
The kappa- mu and eta - mu are general fading distributions, which model line-of-sight and non-line-of-sight propagation effects, respectively. In this work, expressions for the coverage probability and average rate when the user experiences kappa - mu fading with arbitrary values of kappa and mu, and interferers experience eta - mu fading with arbitrary values of eta and mu are derived for downlink of a cellular network. Both expressions can be expressed in terms of sum of Lauricella's function of the fourth kind. Further, using the properties of the special functions, the average rate expression is simplified for various special cases. Finally, simulation results are provided and these match our analytical results.
In this letter, we consider a network of multiple unmanned aerial vehicles (UAVs) where a given number of UAVs are placed at 3-D locations in a finite circular disk shaped region to serve a reference ground user equip...
详细信息
In this letter, we consider a network of multiple unmanned aerial vehicles (UAVs) where a given number of UAVs are placed at 3-D locations in a finite circular disk shaped region to serve a reference ground user equipment (UE) located at its center. Herein, a serving UAV is assumed to be located at fixed altitude which communicates with the reference UE. All the other UAVs in the network are designated as interfering UAVs to the UE and are assumed to have 3-D mobility. To characterize the 3-D UAV movement process, we hereby propose an effective 3-D mobility model based on the mixed random waypoint mobility and uniform mobility models in the vertical and spatial directions. Further, considering the proposed 3-D mobility model, we first characterize the interference received at reference UE, and then evaluate its coverage probability under Nakagami-m fading. We quantify the achievable performance gains for the ground UE under various system and channel conditions. Moreover, we corroborate our analytical results through simulations.
暂无评论