Browsing by Author "Silva, Bruno Cruz da"
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- Optimization of Small Cells Deployment and Frequency Assignment using Spectrum SharingPublication . Silva, Bruno Cruz da; Velez, Fernando José da Silva5G New Radio is an ai r-interface technology with the objective of improving performance, flex¬ibility [1], [2],[3] scalability and efficiency of current mobile networks. 5G NR is envisioned to support multipIe services and devices where the heterogeneous networks will be of such im¬portance with the densification of small cells, and different techniques will be used such as carrier aggregation, spectrum sharing or dual connectivity. This dissertation aims to explore the optimization of small cell networks using the spectrum sharing in the UHF, SHF and mil¬limeter wave bands for urban environments. ln the study, different scenarios and topologies have been considered, while frequencies of 2.6 GHz and 3.5 GHz have been considered for the UHFISHF bands, and 28, 38, 60 and 73 GHz for the millimeter wave bands. A linear topol¬ogy has been considered for the millimeter waves that contains a scenario with sharing and another without shared spectrum, while in the UHF and SHF bands a hexagonal topology has been considered, containing both a scenario without spectrum sharing and six spectrum sharing topologies, divided by its region in the cell, as Northeast, East, Southeast and Soutwest. Propa¬gation models are the Urban Micro LoS for UHFISHF, a two-slope model, and the modified Friis equation for the millimeter waves. Different reuse patterns have also been considered, i.e., k = 3 and k = 4. However, for the millimeter wave scenario only k = 3 has been considered. With the established scenario and the considered models, the performance parameters such as the CNIR, PHY throughput, supported throughput, average CNIRISINR have been obtained and discussed. ln the UHFISHF bands, by comparing the curves for the supported throughput and the average CNIR, we can observe that the trend of the values, i.e., the line shapes, are very similar. The 28 GHz frequency band has the highest supported throughput, reaching 45 Mbps. The supported throughput at the 38, 60 and 73 GHz is higher than the one for the UHFISHF bands for the shortest Rs. For longer coverage distances, the supported throughput is clearly higher for the UHF/SHF frequency bands (compared to the 38, 60 and 73 GHz frequency bands). LTE-Sim, a open source framework developed in the University of Bari [4], commonly known as an event-driven simulator written in C + + has been used for packet-level simulations. Results for the goodput, packet loss ratio and delay have been obtained. One scenario with only a small cell cluster, with one picocell and six co-channel pico cells, has been considered in the simu-lations. The goodput and packet loss ratio achieved by simulation are complementary to each other (where achieved goodput is slightly higher at 2.6 GHz, compared to the 3.5 GHz frequency band). By comparing the analytical and simulation results for the supported throughoutigood¬put (without sharing) there are differences, as analytical results do not consider packet errors, and for a number of users higher than 16 -18, the PLR is too high even for distances longer than 100 -150 m, while for 16 or less users the PLR is only high for coverage distances up to circa 100 m. These differences between analytical and simulation results can be mainly explained by the fact that the number of users are not considered in the analytical formulation (saturation conditions are assumed instead), and also because of the high value for the PLR. The maximum delay is 55 ms. Hence, e.g., for gaming applications, latency will be adequate.