دانلود رایگان مقاله چارچوب انرژی کارآمد برای ارتباط کاربران و تخصیص قدرت در HetNets

Abstract

Dense deployment of femtocells has proved to be an effective solution to handle increasing demands of indoor mobile data. A femtocell not only helps reducing operational and capital expenditure but also improves the energy efficiency of the network. Femtocells are able to increase spectrum efficiency by manyfold by reusing the available spectrum for indoor users. However, it has been seen that traditional cell selection schemes limit the user count under femtocell. Additionally, dense deployment of femtocells comes with the cost of increased interference to the neighbouring femtocell and macrocell users. In this paper, we first analyse various cell selection schemes to improve user association and resource utilization in femtocells. Then, we focus on improving energy efficiency and throughput of femtocell based cellular networks. For this, we formulate an optimization problem that efficiently reuses macrocell spectrum in femtocells with power control while satisfying macrocell users’ interference and rate-loss constraints.

8. Conclusion

In this paper, we have proposed an energy efficient framework for user association and power allocation in femtocell assisted cellular networks. In order to improve the benefits of femtocell deployments, use of cell biasing and expected bitrate based user association is suggested. These schemes offload users from macrocells to femtocells, and consequently improve the femtocell resource utilization and reduce the macrocell energy consumption. Compared to existing cell selection schemes available in the literature, our proposed enhanced expected bitrate scheme has shown to improve throughput of femtocells by 30–35% approximately. Besides protecting signal quality of macrocell users using interference constraint, a new criterion referred to as rate-loss constraint is also proposed. Additionally, an optimal power allocation strategy (HCPC) is devised to efficiently reuse macrocell spectrum in femtocell downlink. The HCPC technique, when used in combination with enhanced expected bitrate scheme, has resulted in an additional 20–26% improvement in throughput of femtocells. Simulation results have verified this improvement in system throughput and energy efficiency. Our suggested HCPC technique achieves the best performance in terms of both system throughput and energy efficiency while protecting macrocell users via interference and rate-loss constraints. Future work in this direction can consider limited femtocell backhaul capacity while performing cell selection and spectrum allocation.