Base Stations Of Cellular Systems Research Articles

Comparison of Four High Performance Dual Polar Antennas for Base Stations

In this paper four types of cross-dipoles antennas, highly compatible to be utilized in base stations of cellular systems, were thoroughly compared: (1) dipoles with sloping-cut arms, (2) dipoles with folded arms, (3) dipoles with helical shape, and (4) dipoles with helical shape and inverted branches. To carry out the comparison, a design of each type of antenna was performed with an objective bandwidth of 1710–1880 MHz and a return loss higher than 15 dB. By computer simulations, some important parameters were examined: mutual coupling, return losses, input impedance, gain stability, beamwidth invariability, cross-pol discrimination and tracking error. From the comparison, it was found that the crossed dipoles with folded arms occupy the lowest volume and have the higher beamwidth stability. On the other hand, the dipoles with helical shape have the lowest mutual coupling, meanwhile the helical dipoles with inverted branches have the higher cross polarization discrimination. To experimentally validate some of these results, a prototype of the crossed dipoles with helical shape was constructed and measured to demonstrate that the simulations are consistent with the real implementation. After all this study is clear that each antenna has advantages and limitations, and depends on the more stringent requirement that a certain application demands, to select one or another type of antenna.

Evolution of Optimal 3D placement of UAV with Minimum Transmit Power

Due to vast technology advancement in communication System, it has been possible to use unmanned aerial vehicle (UAV) that can fly independently and worked remotely without carrying any human personnel. UAV provides new methods for communication in military and civilian application. They have small operating and installation cost. They provide flexible way for communication. Unmanned aerial vehicle can be used as Wireless base station in cellular system providing an alternative communication mechanism for cellular communication in any disaster or emergency situation when existing terrestrial network goes down. However besides these several advantages UAVs has many Unique design challenges for both indoor and outdoor users. Energy limitation is one of the major challenges as each UAV has limited battery source so due to limited battery time completing the task in minimum Hover time is another challenge. Another major challenge is Optimal UAVs placement in such a way that Sum data rate of all the users is maximized. this paper investigate the problem of Optimal UAVs placement and minimum transmit power through which better signal to noise ratio is achieved for indoor users, first proved our problem is mixed integer non- linear problem and our objective function is convex and use Genetic algorithm and Nomad to solve our problem, Through Numerical result conclude that optimal placement of UAVs is achieved with minimum path loss and minimum transmit power required to cover indoor user.

Coexistence of MIMO Radar and FD MIMO Cellular Systems With QoS Considerations

In this work, the feasibility of spectrum sharing between a multiple-input multiple-output (MIMO) radar system (RS) and a MIMO cellular system (CS), comprising of a full duplex (FD) base station (BS) serving multiple downlink and uplink users at the same time and frequency is investigated. While a joint transceiver design technique at the CS's BS and users is proposed to maximise the probability of detection (PoD) of the MIMO RS, subject to constraints of quality of service (QoS) of users and transmit power at the CS, null-space based waveform projection is used to mitigate the interference from RS towards CS. In particular, the proposed technique optimises the performance of PoD of RS by maximising its lower bound, which is obtained by exploiting the monotonically increasing relationship of PoD and its non-centrality parameter. Numerical results show the utility of the proposed spectrum sharing framework, but with certain trade-offs in performance corresponding to RS's transmit power, RS's PoD, CS's residual self interference power at the FD BS and QoS of users.

Secrecy Outage Analysis in Cellular Networks

The study of the inherent secrecy capacity of wireless networks of random topologies is currently of great interest to the communication and information theory communities. Indeed, a good amount of work exists on the secrecy analysis of random networks, the majority of which relies on Poisson point processes to model the spatial distribution of devices. It has been recently demonstrated, however, that Matern hard-core point processes—rather than Poisson point processes—are better suited to characterize the random location of users and base stations of cellular systems. In this letter, we therefore offer an analysis of the secrecy outage of random networks under the Matern hard-core point process model, with the objective of shedding some light on the security limitations/capabilities inherent encountered in cellular systems.

Delay-aware cross-layer design for device-to-device communications in future cellular systems

Device-to-device (D2D) communications allow direct communications between nodes without transmitting data via the base stations in cellular systems, which could bring significant performance improvement. Since most applications are delay-sensitive, it is very important to consider delay performance in addition to physical layer throughput for D2D communications. To improve delay performance it is necessary to dynamically control the radio resource in a cross-layer way according to both the channel fading information and the queue length information. The former allows an observation of good transmission opportunity and the latter provides the urgency of data flows. However, the resource control with delay constraints involves stochastic optimization, which is very challenging. In this article we first summarize various approaches to solve the delay-aware resource allocation problems for D2D communications. We propose a low complexity practical solution by exploiting the interference filtering property of CSMA-like MAC protocols in the D2D system. Based on the solution structure, we further discuss the implementation issues based on LTE-Advanced systems and evaluate the associated performance and complexity. Finally we discuss the choice of MAC parameters for the overall D2D system performance.

A broadband probe‐fed patch antenna for a DCS base station

AbstractThis paper presents a novel broadband design of a probe‐fed patch antenna, and a constructed prototype suitable for applications in a DCS (1710–1880 MHz) cellular system base station is demonstrated. The proposed antenna has a thick air substrate for broadband operation, and is fed by a probe feed with a short probe pin, which is connected through a triangular conducting patch to one of the patch's radiating edges. By tuning the flare angle of the triangular conducting patch, good impedance matching over a wide frequency range is obtained. Details of the proposed antenna and experimental results of the constructed prototypes are presented and discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 341–343, 2001.