The Research Of Key Technology In Two-Tier Femtocell Networks

Wireless operators are in the process of augmenting the macrocell network with supplemental infrastructure such as macrocells, distributed antennas and relays. However, as the link efficiency is approaching its fundamental limits, the nodes trend to be dense, and the site acquisition and the other cost in a capacity limited dense urban area gets prohibitively expensive, it’s impossible to increase the network capacity by increasing the number of the nodes. The white paper of LTE-Advance points out that an alternative solution with lower upfront costs is to improve indoor coverage and capacity using the concept of edge-consumer installed femtocells or what is so called home base stations. In fact, the research of the technology is the key that we benefit the higher diversity and multiplexing, more capacity, and better user experience from the femtocell. The research about the femtocell in one of the hot topic in recent research field.Under this situation, the dissertation firstly describes the concept of the two-tier femtocell heterogeneous networks and makes a conclusion of what is going on in the scientific research field all around the world. Then, in accor-dance with the scenario of the femtocell model, the dissertation do the best research in the problems about the outage probability, resource allocation and so on. The dissertation focus our energies on the key technology of the two-tier femtocell heterogeneous networks, whereby our contributions are listed as following.Firstly, in terms of the interference from the neighbour cells, the disserta-tion proposes the model of power-shot noise to calculate the outage probability of the users and the optimal ratio of macrocell base station to femtocell base station. The scheme means to maximize the capacity of the networks. The results are well analysed and demonstrated by the simulation effectively.Secondly, the dissertation proposes a feasible power control scheme, which aims at analysing the fairness of the femntocell networks. The feasibility of the maximal number of the femtocell base station in the simulation model can be well demonstrated by this.At last, the dissertation proposes a cognitive radio relay selection shecem to management the cross-tier interference. The scheme purposes to improve the capacity of the femto-networks with the QoS of macrocell user guaranteed. On the one hand, for the macro-network, the scheme is intended to ensure the macrocell users can endure much more interference from the femtocell users. On the other hand, with respect to the femto-networks, the scheme can ef-fectively improve the received signal strength relative to cross-tier macrocell interference of the femtocell users. As a result, the femtocell users can obtain a relative improvement in their Signal-to-Interference-plus-Noise-Ratio (SINR). Simulation results demonstrate that, compared with the existing works, the pro-posed scheme can not only increase the number of the successful femtocell users, but also improve the average SINR of the femtocell users.