دانلود رایگان مقاله آفلودینگ مبتنی بر فمتو هیبریدی/ نرخ کلان برای شبکه با تراکم کاربری بالا

Abstract

Nowadays, the popularity of smart phones creates huge capacity requirements for networks during mass events where thousands of people coexist in specific areas. At such events, large numbers of people use their smartphones to share pictures and download information. This behavior creates traffic profiles that differ from those typically observed in legacy -less populated- networks where lower uplink traffic volumes are generated. Thus, novel network planning and radio resource management mechanisms have to be considered for such dense network conditions, one of which is macrocell offloading. In this context, reducing the cell size has always been the best way to increase the network capacity of LTE. Femtocells are used to enable offloading data-traffic from macrocell network to increase the capacity. In this paper, to achieve efficient user offloading from macro to femtocells, we propose an offloading algorithm based on a perceived rate threshold in combination with uplink power control for hybrid femtocells also considering resource block partitioning. The proposed algorithm enhances the network capacity so that more mobile users can satisfy their minimum Quality of Service (QoS) requirements, thus the overall performance of dense cellular networks increases. The proposed offloading mechanism is assessed in terms of the achieved total throughput and outage probability figures. Simulation results demonstrate the potential increase of the number of supported users per macrocell in joint macro and hybrid femtocell deployments.

5. Conclusion

This paper has focused on the issue of the performance of cochannel macrocells and femtocells in high user density areas. We have evaluated the capacity performance of a two-tier femtocell network under different access control modes. In the closed access mode, handoff to nearby femtocells is not possible and, thus, the number of dropped users increases sharply at high user densities resulting in an increase in the outage probability. In the case of the hybrid mode, cellular users are assigned to a nearby femtocell as a result of the proposed hybrid femto/macro rate-based offloading algorithm that includes RBO. Our algorithm essentially combines RBO with power control and OSFR for resource allocation. Simulation results showed that the proposed hybrid femto/macro ratebased offloading can effectively increase coverage and capacity by optimally assigning users to cell tiers and resources to users.