Um Algoritmo de CAC com Reserva Dinâmica de Recursos e Preempção para Redes LTE

Abstract

Long Term Evolution (LTE) technology was devised by the 3rd Generation Partnership Project (3GPP) to provide its users with higher data transfer rates and a more satisfying quality of experience.

The guarantee of quality of service (QoS) to users has become an important part of the development of LTE technology, as it is essential for the availability of applications such as voice and video, which are increasingly in demand. In LTE networks, QoS is guaranteed from Radio Resource Management (RRM), through algorithms that lead how finite network resources are shared among all users.

Among the RRM algorithms, CAC - Call Admission Control is one of the most relevant: it takes the decision to admit or reject a connection, based on the type of the connection, your requirements of QoS and the network occupancy rate. Since it is impractical to admit all connection requests, it aims to assure that radio resources are used optimally to meet the QoS requirements of the admitted connections, thus expecting the user to have a satisfactory quality of experience.

Because the LTE standard does not specify mechanisms for connection admissions, it is proposed in this work a call admission control algorithm (CAC), capable of attending the main classes of services defined by the standard. The strategy of the CAC algorithm presented in this work prioritizes GBR (Guaranteed Bit Rate) connections and handoff connections (calls that are already in progress) through the dynamic adaptation of reserved sections of the bandwidth and preemption of non-GBR connections, which are more tolerant to the reduction of data rate.

The evaluation of the efficiency of the proposed CAC algorithm was done through modeling and simulation in a typically urban scenario. Their results were compared with the results of other CAC algorithms found in the literature and quite popular, which were also modeled in the same scenario.

Simulation results show that the functions implemented in the algorithm were able to present a considerable reduction in the rate of connection drops and increase in the number of admitted connections.