Aiding cellular networks by unmanned aerial vehicles (UAVs) is a leap forward to address the ever-rising, multifarious, and dynamic traffic demands. The UAV utilization in wireless communication presents essential advantages, such as position control and appealing Line-of-Sight (LoS) components. In this article, we consider a UAV deployed as an aerial base station (ABS) to assist a terrestrial base station (TBS), serving several users in a hotspot area, via user offloading. Considering unavailable knowledge of the user's locations, the ABS is assumed to hover at the cell center (geometric center) above the TBS as a best-effort location for all the users. Taking into account the mutual interference between the aerial and terrestrial communication links due to spectrum reuse, we study the impact of the ABS altitude and transmit power, as well as the offload portion, on the user's downlink sum rate under the settings of the LoS channel. The results show that the optimal values for the design variables are either the maximum or the minimum boundaries. Also, the results demonstrate that our method outperforms benchmark schemes with appreciable amounts of gain. We also investigate the method's behavior with the ABS horizontal position optimization, probabilistic LoS channel, uplink communication, and orthogonal spectrum allocation.

The wireless communication field is getting closer to the integration of the unmanned aerial vehicle (UAV) and cellular network for further enhanced service quality. In this paper, we study a wireless communication system with coexisting aerial and terrestrial base stations, which respectively serve their associated users. By taking into account the mutual interference between the aerial and terrestrial communication links, we study the impact of the aerial base station (ABS) altitude and transmit power on the system's downlink and uplink data rates. In many situations, the results show that the optimal ABS altitude and transmit power are either the maximum or the minimum possible values depending on, for instance, the relative proximity between the ABS, the ABS user (AU), and the terrestrial base station user (TU).

Software-defined networking (SDN) is a cutting-edge technology, featuring a centralized control that facilitates, e.g., flexible deployment of unmanned aerial vehicles (UAVs). On the other hand, UAV-enabled communication is a promising technology due to its numerous traits such as the ability of on-demand deployment and the high likelihood of strong line-of-sight (LoS) communication links. However, UAV-enabled communication suffers non-perpetual nodes and intermittent communication links. Fortunately, SDN provisions an unparalleled global vision on such dynamic network architecture to overcome the challenges of loose links and disappearing nodes. On the other hand, there are catastrophic or remote regions where a UAV-mounted base station (BS) potentially functions without a terrestrial BS, albeit a WiFi access point (AP) may still exist. Therefore, this paper considers software-defined coexisting UAV-mounted BS (UBS) and WiFi AP, and investigates the queuing delay behavior via the UBS positioning and the AP traffic offloading. The subscribers (users) are divided into cellular subscribers (CSs) and WiFi subscribers (WSs). A CS is connected to the UBS and is possibly granted simultaneous access to the AP, leading to WiFi traffic offloading. Leveraging the software-defined global view, the objective of a software-defined controller (SDC) is to minimize the average M/M/1 queuing delay of the CSs, while guaranteeing the delay performance for the WSs, via optimizing the spectrum allocation, the UBS position, the CS association to the AP, and the CS traffic offloading. The optimization problem is non-convex, comprising binary variables, for which we use the block coordinate descent and successive convex approximation methods to find a high-quality solution. Numerical results verify that our solution achieves significant performance gains over benchmark schemes.

The wireless communication field is approaching the realization of the integrated unmanned aerial vehicle (UAV) and cellular network for further improved communication performance. In this paper, we consider a cellular network with a UAV-mounted aerial base station (ABS) coexisting with multiple terrestrial base stations (TBSs), where each base station (BS) is serving multiple users. Under the probabilistic channel based environment, we design the three-dimensional (3D) positioning for the ABS and the transmit power allocation for all the nodes in the uplink (UL), downlink (DL), and combined UL and DL operations. Considering the ABS user (AU) and the TBS user (TU) as contending parties, our objective is to maximize the weighted sum of the minimum data rate of the AUs and the minimum data rate of the TUs. The whole optimization problem is non-convex and difficult to be directly solved, for which we employ the block coordinate descent (BCD), the successive convex approximation (SCA), the particle swarm optimization (PSO), and the discrete search algorithm (DSA) methods. Numerical results shed some light on interesting observations regarding the comparison between our solution and benchmark schemes, as well as the optimal 3D position of the ABS in UL, DL, and combined UL and DL operations.

In this study, the authors evaluate the capacity by summation of granted bit rates in their proposed quality of service‐aware scheduling strategy for long term evolution (LTE). To provision differentiation, the scheduling technique prioritises the queues for high priority (HP) applications against their low priority (LP) counterparts. Fairness, on the other hand, is supported by considering queue overflow of LP applications. They utilised the principles of a random variable to derive equations for the capacities offered by their method and used the token bucket technique to address the principle of the guaranteed‐bit‐rate for HP applications, referring to the guaranteed capacity in LTE. Experimental findings confirm that their strategy could extend the capacity granted to LP applications and simultaneously maintain the capacity condition for HP applications. The results also show relative improvement and acceptable degradation in the capacities granted to the LP and HP applications in their scheme when compared with other methods.

In this article we propose a harmonious licensed-unlicensed spectrum management framework for LTE and WiFi coexisting in a software defined environment. Two key resource dimensions are employed, bandwidth and Virtual Queues (VQs), in conjunction with a third resource dimension, i.e. time. The full potential of this novel approach lies in the replacement of inter-technology carrier sensing with centrally managed resource access via leveraging the global view of Software Defined Networking (SDN). Results illustrate that the proposed paradigm addresses together selectivity and fairness for LTE and WiFi, as well as demands for both high and low priority traffic. The outcomes also show holistic superiority for our framework when compared with two other benchmark schemes.

The next generation of mobile broadband technologies, namely the Fifth Generation (5G), will include an integration of legacy technologies like the Long Term Evolution (LTE), the Worldwide Interoperability for Microwave Access (WìMaX), the Wireless Fidelity (Wi-Fi), etc. However, Quality of Service (QoS) details are not fully defined for the integrated networks, and the subject is left open to be explored by the vendors. Provisioning of QoS guarantees for a heterogeneous network is contingent upon the execution of an appropriate mapping among the QoS classes of the participating technologies. LTE and WiMAX are two flourishing technologies in the Fourth Generation (4G) and will remain so in 5G. Therefore, an adaptive QoS class mapping strategy is proposed for the incorporated LTE-WiMAX 5G Network. Simulation results revealed a satisfying performance in terms of QoS measures such as response time and Packet Loss Rate (PLR) for almost all types of traffic.

Long Term Evolution (LTE) is rapidly flourishing in the global market due to its speed, coverage, relative ease of deployment, and consistency. However, Quality of Service (QoS) provisioning scheme is not fully defined for LTE, and it is left open for researchers to explore. In this paper, we propose a QoS provisioning technique for LTE. This technique involves a two-level scheduling scheme, consisting of a Rate-Controlled Priority Queuing Discipline (RCPQD) and a Deficit Weighted Round Robin Queuing Discipline (DWRRQD). To provision fairness, the scheduler considers the buffer content of the non-real-time applications, while priority is used to take differentiation of RT applications into account. The results show relative improvement in the performance of both real-time and non-real-time applications.