Handover Algorithm Study In Femtocell Network Based On LTE

In LTE system, the significant increase of demand for high-speed data serviceand the number of users, bring increasing burden and challenge to the macro basestation. The propagation loss and wall penetration loss of LTE system are pretty largebecause of the using of high frequency, which lead to poor indoor signal coverage.Femtocell, a kind of small base stations, although can improve indoor coverageeffectively, but also brings challenges of key technologies at the same time, which hasbeen the focus of the field of mobile communications.In this paper, there are mainly two aspects to optimize the LTE-femtocellnetwork: interference and two-tier network handover. The primary contributions areas follows:1. According to the introduction of related specifications and books, analyzedand summarized various handover and interference scenes in LTE-femtocell network.In addition, researched and determined the models and parameters required inbuilding two-tier network simulation platform, including antenna model, path lossmodel, deployment model, transmitting power and so on.2. Successfully established the two-tier network simulation platform onMATLAB which contains scheduling, power control and handover function modules.The performance of two-tier network was compared and analyzed on the establishedsimulation platform;3. The advantages and disadvantages of the existing classic handover algorithmswere summarized and analyzed. On this basis, this paper proposed a new kind ofhandover algorithm, which considered UEs’ type, adaptively adjusted HOM based onthe current load of the target cell, and combined with the power control algorithm.The users in the nearby areas of the coverage may be interfered obviously, so HeNBswill adjust their transmit power dynamically according to the number of those users’initiated handover request and call drop; And the users in the coverage boundary willuse the improved CAC algorithm which can adaptively adjust HOM based on thecurrent load of the target cell.After simulations, the network capacity and system throughput are improvedunder the two-tier network environment, but with the increase of the number ofHeNBs, handover and interference problems become prominent increasingly, whichlead to the growth trend of system throughput and average throughput subject tocertain restrictions. Compared with the standard and CAC algorithms, though theproposed handover algorithm are more complicated, it reduced interference, call drop rate as well as unnecessary handover times. What’s more, it improved the throughputof cell-edge users, thereby enhanced the system overall throughput.