Development of Base Transceiver Station Selection Algorithm for Collocation Arrangement

Placement of base transceiver station (BTSs) by different operators on a particular site as collocation site, so as to save cost and reduce the number of people who are at  risk of radiation in BTSs located places as compared to each operator having different BTSs is the new trend in Nigeria telecommunication industries development. Collocation of base stations is much safer when compared to scattered base station telecommunication operators because of the radiations. Although the International Commission on Non-Ionizing Radiation Protection (ICNIRP) viewed that the presently existing scientific verification that prolonged contact with low frequency magnetic fields is more often than not connected with an increased danger of childhood leukaemia is too frail to form the basis for exposure guidelines.  This work includes the study, analysis and proposal of a collocation scheme based on collected data of the number of BTS already sited in University of Ilorin, Ilorin, Nigeria as a case study. A drive test conducted with Transmission Environmental Monitoring System (TEMS) equipment was carried out on the existing BTSs, and a linear algorithm optimization program based on the spectral link efficiency of each BTS was developed, the output of this site optimization gives the selected number of base station sites to be used for the collocation arrangement, and the BTSs site with the best spectral link efficiency are selected in accordance with the output of the site optimization for the collocation.http://dx.doi.org/10.4314/njt.v34i3.1

Multicell MIMO Communications Relying on Intelligent Reflecting Surfaces

Intelligent reflecting surfaces (IRSs) constitute a disruptive wireless communication technique capable of creating a controllable propagation environment. In this paper, we propose to invoke an IRS at the cell boundary of multiple cells to assist the downlink transmission to cell-edge users, whilst mitigating the inter-cell interference, which is a crucial issue in multicell communication systems. We aim for maximizing the weighted sum rate (WSR) of all users through jointly optimizing the active precoding matrices at the base stations (BSs) and the phase shifts at the IRS subject to each BS’s power constraint and unit modulus constraint. Both the BSs and the users are equipped with multiple antennas, which enhances the spectral efficiency by exploiting the spatial multiplexing gain. Due to the nonconvexity of the problem, we first reformulate it into an equivalent one, which is solved by using the block coordinate descent (BCD) algorithm, where the precoding matrices and phase shifts are alternately optimized. The optimal precoding matrices can be obtained in closed form, when fixing the phase shifts. A pair of efficient algorithms are proposed for solving the phase shift optimization problem, namely the Majorization-Minimization (MM) Algorithm and the Complex Circle Manifold (CCM) Method. Both algorithms are guaranteed to converge to at least locally optimal solutions. We also extend the proposed algorithms to the more general multiple-IRS and network MIMO scenarios. Finally, our simulation results confirm the advantages of introducing IRSs in enhancing the cell-edge user performance

Power Estimation in LTE systems with the General Framework of Standard Interference Mappings

We devise novel techniques to obtain the downlink power inducing a given load in long-term evolution (LTE) systems, where we define load as the fraction of resource blocks in the time-frequency grid being requested by users from a given base station. These techniques are particularly important because previous studies have proved that the data rate requirement of users can be satisfied with lower transmit energy if we allow the load to increase. Those studies have also shown that obtaining the power assignment from a desired load profile can be posed as a fixed point problem involving standard interference mappings, but so far the mappings have not been obtained explicitly. One of our main contributions in this study is to close this gap. We derive an interference mapping having as its fixed point the power assignment inducing a desired load, assuming that such an assignment exists. Having this mapping in closed form, we simplify the proof of the aforementioned known results, and we also devise novel iterative algorithms for power computation that have many numerical advantages over previous methods.Comment: IEEE Global SIP 201